Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 6319 insertions, 0 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
new file mode 100644
index 000000000..365c4d3a4
--- /dev/null
+++ b/fs/ext4/inode.c
@@ -0,0 +1,6319 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/ext4/inode.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/inode.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  64-bit file support on 64-bit platforms by Jakub Jelinek
+ *	(jj@sunsite.ms.mff.cuni.cz)
+ *
+ *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
+ */
+
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/highuid.h>
+#include <linux/pagemap.h>
+#include <linux/dax.h>
+#include <linux/quotaops.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/pagevec.h>
+#include <linux/mpage.h>
+#include <linux/namei.h>
+#include <linux/uio.h>
+#include <linux/bio.h>
+#include <linux/workqueue.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/iomap.h>
+#include <linux/iversion.h>
+
+#include "ext4_jbd2.h"
+#include "xattr.h"
+#include "acl.h"
+#include "truncate.h"
+
+#include <trace/events/ext4.h>
+
+static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
+			      struct ext4_inode_info *ei)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	__u32 csum;
+	__u16 dummy_csum = 0;
+	int offset = offsetof(struct ext4_inode, i_checksum_lo);
+	unsigned int csum_size = sizeof(dummy_csum);
+
+	csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw, offset);
+	csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, csum_size);
+	offset += csum_size;
+	csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
+			   EXT4_GOOD_OLD_INODE_SIZE - offset);
+
+	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
+		offset = offsetof(struct ext4_inode, i_checksum_hi);
+		csum = ext4_chksum(sbi, csum, (__u8 *)raw +
+				   EXT4_GOOD_OLD_INODE_SIZE,
+				   offset - EXT4_GOOD_OLD_INODE_SIZE);
+		if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
+			csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
+					   csum_size);
+			offset += csum_size;
+		}
+		csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
+				   EXT4_INODE_SIZE(inode->i_sb) - offset);
+	}
+
+	return csum;
+}
+
+static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
+				  struct ext4_inode_info *ei)
+{
+	__u32 provided, calculated;
+
+	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
+	    cpu_to_le32(EXT4_OS_LINUX) ||
+	    !ext4_has_metadata_csum(inode->i_sb))
+		return 1;
+
+	provided = le16_to_cpu(raw->i_checksum_lo);
+	calculated = ext4_inode_csum(inode, raw, ei);
+	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
+	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
+		provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
+	else
+		calculated &= 0xFFFF;
+
+	return provided == calculated;
+}
+
+void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
+			 struct ext4_inode_info *ei)
+{
+	__u32 csum;
+
+	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
+	    cpu_to_le32(EXT4_OS_LINUX) ||
+	    !ext4_has_metadata_csum(inode->i_sb))
+		return;
+
+	csum = ext4_inode_csum(inode, raw, ei);
+	raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
+	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
+	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
+		raw->i_checksum_hi = cpu_to_le16(csum >> 16);
+}
+
+static inline int ext4_begin_ordered_truncate(struct inode *inode,
+					      loff_t new_size)
+{
+	trace_ext4_begin_ordered_truncate(inode, new_size);
+	/*
+	 * If jinode is zero, then we never opened the file for
+	 * writing, so there's no need to call
+	 * jbd2_journal_begin_ordered_truncate() since there's no
+	 * outstanding writes we need to flush.
+	 */
+	if (!EXT4_I(inode)->jinode)
+		return 0;
+	return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
+						   EXT4_I(inode)->jinode,
+						   new_size);
+}
+
+static void ext4_invalidatepage(struct page *page, unsigned int offset,
+				unsigned int length);
+static int __ext4_journalled_writepage(struct page *page, unsigned int len);
+static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
+static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
+				  int pextents);
+
+/*
+ * Test whether an inode is a fast symlink.
+ * A fast symlink has its symlink data stored in ext4_inode_info->i_data.
+ */
+int ext4_inode_is_fast_symlink(struct inode *inode)
+{
+	if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
+		int ea_blocks = EXT4_I(inode)->i_file_acl ?
+				EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;
+
+		if (ext4_has_inline_data(inode))
+			return 0;
+
+		return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
+	}
+	return S_ISLNK(inode->i_mode) && inode->i_size &&
+	       (inode->i_size < EXT4_N_BLOCKS * 4);
+}
+
+/*
+ * Called at the last iput() if i_nlink is zero.
+ */
+void ext4_evict_inode(struct inode *inode)
+{
+	handle_t *handle;
+	int err;
+	/*
+	 * Credits for final inode cleanup and freeing:
+	 * sb + inode (ext4_orphan_del()), block bitmap, group descriptor
+	 * (xattr block freeing), bitmap, group descriptor (inode freeing)
+	 */
+	int extra_credits = 6;
+	struct ext4_xattr_inode_array *ea_inode_array = NULL;
+	bool freeze_protected = false;
+
+	trace_ext4_evict_inode(inode);
+
+	if (EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)
+		ext4_evict_ea_inode(inode);
+	if (inode->i_nlink) {
+		/*
+		 * When journalling data dirty buffers are tracked only in the
+		 * journal. So although mm thinks everything is clean and
+		 * ready for reaping the inode might still have some pages to
+		 * write in the running transaction or waiting to be
+		 * checkpointed. Thus calling jbd2_journal_invalidatepage()
+		 * (via truncate_inode_pages()) to discard these buffers can
+		 * cause data loss. Also even if we did not discard these
+		 * buffers, we would have no way to find them after the inode
+		 * is reaped and thus user could see stale data if he tries to
+		 * read them before the transaction is checkpointed. So be
+		 * careful and force everything to disk here... We use
+		 * ei->i_datasync_tid to store the newest transaction
+		 * containing inode's data.
+		 *
+		 * Note that directories do not have this problem because they
+		 * don't use page cache.
+		 */
+		if (inode->i_ino != EXT4_JOURNAL_INO &&
+		    ext4_should_journal_data(inode) &&
+		    (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode)) &&
+		    inode->i_data.nrpages) {
+			journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+			tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
+
+			jbd2_complete_transaction(journal, commit_tid);
+			filemap_write_and_wait(&inode->i_data);
+		}
+		truncate_inode_pages_final(&inode->i_data);
+
+		goto no_delete;
+	}
+
+	if (is_bad_inode(inode))
+		goto no_delete;
+	dquot_initialize(inode);
+
+	if (ext4_should_order_data(inode))
+		ext4_begin_ordered_truncate(inode, 0);
+	truncate_inode_pages_final(&inode->i_data);
+
+	/*
+	 * For inodes with journalled data, transaction commit could have
+	 * dirtied the inode. And for inodes with dioread_nolock, unwritten
+	 * extents converting worker could merge extents and also have dirtied
+	 * the inode. Flush worker is ignoring it because of I_FREEING flag but
+	 * we still need to remove the inode from the writeback lists.
+	 */
+	if (!list_empty_careful(&inode->i_io_list))
+		inode_io_list_del(inode);
+
+	/*
+	 * Protect us against freezing - iput() caller didn't have to have any
+	 * protection against it. When we are in a running transaction though,
+	 * we are already protected against freezing and we cannot grab further
+	 * protection due to lock ordering constraints.
+	 */
+	if (!ext4_journal_current_handle()) {
+		sb_start_intwrite(inode->i_sb);
+		freeze_protected = true;
+	}
+
+	if (!IS_NOQUOTA(inode))
+		extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);
+
+	/*
+	 * Block bitmap, group descriptor, and inode are accounted in both
+	 * ext4_blocks_for_truncate() and extra_credits. So subtract 3.
+	 */
+	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
+			 ext4_blocks_for_truncate(inode) + extra_credits - 3);
+	if (IS_ERR(handle)) {
+		ext4_std_error(inode->i_sb, PTR_ERR(handle));
+		/*
+		 * If we're going to skip the normal cleanup, we still need to
+		 * make sure that the in-core orphan linked list is properly
+		 * cleaned up.
+		 */
+		ext4_orphan_del(NULL, inode);
+		if (freeze_protected)
+			sb_end_intwrite(inode->i_sb);
+		goto no_delete;
+	}
+
+	if (IS_SYNC(inode))
+		ext4_handle_sync(handle);
+
+	/*
+	 * Set inode->i_size to 0 before calling ext4_truncate(). We need
+	 * special handling of symlinks here because i_size is used to
+	 * determine whether ext4_inode_info->i_data contains symlink data or
+	 * block mappings. Setting i_size to 0 will remove its fast symlink
+	 * status. Erase i_data so that it becomes a valid empty block map.
+	 */
+	if (ext4_inode_is_fast_symlink(inode))
+		memset(EXT4_I(inode)->i_data, 0, sizeof(EXT4_I(inode)->i_data));
+	inode->i_size = 0;
+	err = ext4_mark_inode_dirty(handle, inode);
+	if (err) {
+		ext4_warning(inode->i_sb,
+			     "couldn't mark inode dirty (err %d)", err);
+		goto stop_handle;
+	}
+	if (inode->i_blocks) {
+		err = ext4_truncate(inode);
+		if (err) {
+			ext4_error_err(inode->i_sb, -err,
+				       "couldn't truncate inode %lu (err %d)",
+				       inode->i_ino, err);
+			goto stop_handle;
+		}
+	}
+
+	/* Remove xattr references. */
+	err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
+				      extra_credits);
+	if (err) {
+		ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
+stop_handle:
+		ext4_journal_stop(handle);
+		ext4_orphan_del(NULL, inode);
+		if (freeze_protected)
+			sb_end_intwrite(inode->i_sb);
+		ext4_xattr_inode_array_free(ea_inode_array);
+		goto no_delete;
+	}
+
+	/*
+	 * Kill off the orphan record which ext4_truncate created.
+	 * AKPM: I think this can be inside the above `if'.
+	 * Note that ext4_orphan_del() has to be able to cope with the
+	 * deletion of a non-existent orphan - this is because we don't
+	 * know if ext4_truncate() actually created an orphan record.
+	 * (Well, we could do this if we need to, but heck - it works)
+	 */
+	ext4_orphan_del(handle, inode);
+	EXT4_I(inode)->i_dtime	= (__u32)ktime_get_real_seconds();
+
+	/*
+	 * One subtle ordering requirement: if anything has gone wrong
+	 * (transaction abort, IO errors, whatever), then we can still
+	 * do these next steps (the fs will already have been marked as
+	 * having errors), but we can't free the inode if the mark_dirty
+	 * fails.
+	 */
+	if (ext4_mark_inode_dirty(handle, inode))
+		/* If that failed, just do the required in-core inode clear. */
+		ext4_clear_inode(inode);
+	else
+		ext4_free_inode(handle, inode);
+	ext4_journal_stop(handle);
+	if (freeze_protected)
+		sb_end_intwrite(inode->i_sb);
+	ext4_xattr_inode_array_free(ea_inode_array);
+	return;
+no_delete:
+	/*
+	 * Check out some where else accidentally dirty the evicting inode,
+	 * which may probably cause inode use-after-free issues later.
+	 */
+	WARN_ON_ONCE(!list_empty_careful(&inode->i_io_list));
+
+	if (!list_empty(&EXT4_I(inode)->i_fc_list))
+		ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_NOMEM);
+	ext4_clear_inode(inode);	/* We must guarantee clearing of inode... */
+}
+
+#ifdef CONFIG_QUOTA
+qsize_t *ext4_get_reserved_space(struct inode *inode)
+{
+	return &EXT4_I(inode)->i_reserved_quota;
+}
+#endif
+
+/*
+ * Called with i_data_sem down, which is important since we can call
+ * ext4_discard_preallocations() from here.
+ */
+void ext4_da_update_reserve_space(struct inode *inode,
+					int used, int quota_claim)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct ext4_inode_info *ei = EXT4_I(inode);
+
+	spin_lock(&ei->i_block_reservation_lock);
+	trace_ext4_da_update_reserve_space(inode, used, quota_claim);
+	if (unlikely(used > ei->i_reserved_data_blocks)) {
+		ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
+			 "with only %d reserved data blocks",
+			 __func__, inode->i_ino, used,
+			 ei->i_reserved_data_blocks);
+		WARN_ON(1);
+		used = ei->i_reserved_data_blocks;
+	}
+
+	/* Update per-inode reservations */
+	ei->i_reserved_data_blocks -= used;
+	percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
+
+	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+
+	/* Update quota subsystem for data blocks */
+	if (quota_claim)
+		dquot_claim_block(inode, EXT4_C2B(sbi, used));
+	else {
+		/*
+		 * We did fallocate with an offset that is already delayed
+		 * allocated. So on delayed allocated writeback we should
+		 * not re-claim the quota for fallocated blocks.
+		 */
+		dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
+	}
+
+	/*
+	 * If we have done all the pending block allocations and if
+	 * there aren't any writers on the inode, we can discard the
+	 * inode's preallocations.
+	 */
+	if ((ei->i_reserved_data_blocks == 0) &&
+	    !inode_is_open_for_write(inode))
+		ext4_discard_preallocations(inode, 0);
+}
+
+static int __check_block_validity(struct inode *inode, const char *func,
+				unsigned int line,
+				struct ext4_map_blocks *map)
+{
+	if (ext4_has_feature_journal(inode->i_sb) &&
+	    (inode->i_ino ==
+	     le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
+		return 0;
+	if (!ext4_inode_block_valid(inode, map->m_pblk, map->m_len)) {
+		ext4_error_inode(inode, func, line, map->m_pblk,
+				 "lblock %lu mapped to illegal pblock %llu "
+				 "(length %d)", (unsigned long) map->m_lblk,
+				 map->m_pblk, map->m_len);
+		return -EFSCORRUPTED;
+	}
+	return 0;
+}
+
+int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
+		       ext4_lblk_t len)
+{
+	int ret;
+
+	if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
+		return fscrypt_zeroout_range(inode, lblk, pblk, len);
+
+	ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
+	if (ret > 0)
+		ret = 0;
+
+	return ret;
+}
+
+#define check_block_validity(inode, map)	\
+	__check_block_validity((inode), __func__, __LINE__, (map))
+
+#ifdef ES_AGGRESSIVE_TEST
+static void ext4_map_blocks_es_recheck(handle_t *handle,
+				       struct inode *inode,
+				       struct ext4_map_blocks *es_map,
+				       struct ext4_map_blocks *map,
+				       int flags)
+{
+	int retval;
+
+	map->m_flags = 0;
+	/*
+	 * There is a race window that the result is not the same.
+	 * e.g. xfstests #223 when dioread_nolock enables.  The reason
+	 * is that we lookup a block mapping in extent status tree with
+	 * out taking i_data_sem.  So at the time the unwritten extent
+	 * could be converted.
+	 */
+	down_read(&EXT4_I(inode)->i_data_sem);
+	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
+		retval = ext4_ext_map_blocks(handle, inode, map, 0);
+	} else {
+		retval = ext4_ind_map_blocks(handle, inode, map, 0);
+	}
+	up_read((&EXT4_I(inode)->i_data_sem));
+
+	/*
+	 * We don't check m_len because extent will be collpased in status
+	 * tree.  So the m_len might not equal.
+	 */
+	if (es_map->m_lblk != map->m_lblk ||
+	    es_map->m_flags != map->m_flags ||
+	    es_map->m_pblk != map->m_pblk) {
+		printk("ES cache assertion failed for inode: %lu "
+		       "es_cached ex [%d/%d/%llu/%x] != "
+		       "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
+		       inode->i_ino, es_map->m_lblk, es_map->m_len,
+		       es_map->m_pblk, es_map->m_flags, map->m_lblk,
+		       map->m_len, map->m_pblk, map->m_flags,
+		       retval, flags);
+	}
+}
+#endif /* ES_AGGRESSIVE_TEST */
+
+/*
+ * The ext4_map_blocks() function tries to look up the requested blocks,
+ * and returns if the blocks are already mapped.
+ *
+ * Otherwise it takes the write lock of the i_data_sem and allocate blocks
+ * and store the allocated blocks in the result buffer head and mark it
+ * mapped.
+ *
+ * If file type is extents based, it will call ext4_ext_map_blocks(),
+ * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
+ * based files
+ *
+ * On success, it returns the number of blocks being mapped or allocated.  if
+ * create==0 and the blocks are pre-allocated and unwritten, the resulting @map
+ * is marked as unwritten. If the create == 1, it will mark @map as mapped.
+ *
+ * It returns 0 if plain look up failed (blocks have not been allocated), in
+ * that case, @map is returned as unmapped but we still do fill map->m_len to
+ * indicate the length of a hole starting at map->m_lblk.
+ *
+ * It returns the error in case of allocation failure.
+ */
+int ext4_map_blocks(handle_t *handle, struct inode *inode,
+		    struct ext4_map_blocks *map, int flags)
+{
+	struct extent_status es;
+	int retval;
+	int ret = 0;
+#ifdef ES_AGGRESSIVE_TEST
+	struct ext4_map_blocks orig_map;
+
+	memcpy(&orig_map, map, sizeof(*map));
+#endif
+
+	map->m_flags = 0;
+	ext_debug(inode, "flag 0x%x, max_blocks %u, logical block %lu\n",
+		  flags, map->m_len, (unsigned long) map->m_lblk);
+
+	/*
+	 * ext4_map_blocks returns an int, and m_len is an unsigned int
+	 */
+	if (unlikely(map->m_len > INT_MAX))
+		map->m_len = INT_MAX;
+
+	/* We can handle the block number less than EXT_MAX_BLOCKS */
+	if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
+		return -EFSCORRUPTED;
+
+	/* Lookup extent status tree firstly */
+	if (!(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) &&
+	    ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
+		if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
+			map->m_pblk = ext4_es_pblock(&es) +
+					map->m_lblk - es.es_lblk;
+			map->m_flags |= ext4_es_is_written(&es) ?
+					EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
+			retval = es.es_len - (map->m_lblk - es.es_lblk);
+			if (retval > map->m_len)
+				retval = map->m_len;
+			map->m_len = retval;
+		} else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
+			map->m_pblk = 0;
+			retval = es.es_len - (map->m_lblk - es.es_lblk);
+			if (retval > map->m_len)
+				retval = map->m_len;
+			map->m_len = retval;
+			retval = 0;
+		} else {
+			BUG();
+		}
+#ifdef ES_AGGRESSIVE_TEST
+		ext4_map_blocks_es_recheck(handle, inode, map,
+					   &orig_map, flags);
+#endif
+		goto found;
+	}
+
+	/*
+	 * Try to see if we can get the block without requesting a new
+	 * file system block.
+	 */
+	down_read(&EXT4_I(inode)->i_data_sem);
+	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
+		retval = ext4_ext_map_blocks(handle, inode, map, 0);
+	} else {
+		retval = ext4_ind_map_blocks(handle, inode, map, 0);
+	}
+	if (retval > 0) {
+		unsigned int status;
+
+		if (unlikely(retval != map->m_len)) {
+			ext4_warning(inode->i_sb,
+				     "ES len assertion failed for inode "
+				     "%lu: retval %d != map->m_len %d",
+				     inode->i_ino, retval, map->m_len);
+			WARN_ON(1);
+		}
+
+		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
+				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
+		if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
+		    !(status & EXTENT_STATUS_WRITTEN) &&
+		    ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
+				       map->m_lblk + map->m_len - 1))
+			status |= EXTENT_STATUS_DELAYED;
+		ret = ext4_es_insert_extent(inode, map->m_lblk,
+					    map->m_len, map->m_pblk, status);
+		if (ret < 0)
+			retval = ret;
+	}
+	up_read((&EXT4_I(inode)->i_data_sem));
+
+found:
+	if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
+		ret = check_block_validity(inode, map);
+		if (ret != 0)
+			return ret;
+	}
+
+	/* If it is only a block(s) look up */
+	if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
+		return retval;
+
+	/*
+	 * Returns if the blocks have already allocated
+	 *
+	 * Note that if blocks have been preallocated
+	 * ext4_ext_get_block() returns the create = 0
+	 * with buffer head unmapped.
+	 */
+	if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
+		/*
+		 * If we need to convert extent to unwritten
+		 * we continue and do the actual work in
+		 * ext4_ext_map_blocks()
+		 */
+		if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
+			return retval;
+
+	/*
+	 * Here we clear m_flags because after allocating an new extent,
+	 * it will be set again.
+	 */
+	map->m_flags &= ~EXT4_MAP_FLAGS;
+
+	/*
+	 * New blocks allocate and/or writing to unwritten extent
+	 * will possibly result in updating i_data, so we take
+	 * the write lock of i_data_sem, and call get_block()
+	 * with create == 1 flag.
+	 */
+	down_write(&EXT4_I(inode)->i_data_sem);
+
+	/*
+	 * We need to check for EXT4 here because migrate
+	 * could have changed the inode type in between
+	 */
+	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
+		retval = ext4_ext_map_blocks(handle, inode, map, flags);
+	} else {
+		retval = ext4_ind_map_blocks(handle, inode, map, flags);
+
+		if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
+			/*
+			 * We allocated new blocks which will result in
+			 * i_data's format changing.  Force the migrate
+			 * to fail by clearing migrate flags
+			 */
+			ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
+		}
+	}
+
+	if (retval > 0) {
+		unsigned int status;
+
+		if (unlikely(retval != map->m_len)) {
+			ext4_warning(inode->i_sb,
+				     "ES len assertion failed for inode "
+				     "%lu: retval %d != map->m_len %d",
+				     inode->i_ino, retval, map->m_len);
+			WARN_ON(1);
+		}
+
+		/*
+		 * We have to zeroout blocks before inserting them into extent
+		 * status tree. Otherwise someone could look them up there and
+		 * use them before they are really zeroed. We also have to
+		 * unmap metadata before zeroing as otherwise writeback can
+		 * overwrite zeros with stale data from block device.
+		 */
+		if (flags & EXT4_GET_BLOCKS_ZERO &&
+		    map->m_flags & EXT4_MAP_MAPPED &&
+		    map->m_flags & EXT4_MAP_NEW) {
+			ret = ext4_issue_zeroout(inode, map->m_lblk,
+						 map->m_pblk, map->m_len);
+			if (ret) {
+				retval = ret;
+				goto out_sem;
+			}
+		}
+
+		/*
+		 * If the extent has been zeroed out, we don't need to update
+		 * extent status tree.
+		 */
+		if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
+		    ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
+			if (ext4_es_is_written(&es))
+				goto out_sem;
+		}
+		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
+				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
+		if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
+		    !(status & EXTENT_STATUS_WRITTEN) &&
+		    ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
+				       map->m_lblk + map->m_len - 1))
+			status |= EXTENT_STATUS_DELAYED;
+		ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
+					    map->m_pblk, status);
+		if (ret < 0) {
+			retval = ret;
+			goto out_sem;
+		}
+	}
+
+out_sem:
+	up_write((&EXT4_I(inode)->i_data_sem));
+	if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
+		ret = check_block_validity(inode, map);
+		if (ret != 0)
+			return ret;
+
+		/*
+		 * Inodes with freshly allocated blocks where contents will be
+		 * visible after transaction commit must be on transaction's
+		 * ordered data list.
+		 */
+		if (map->m_flags & EXT4_MAP_NEW &&
+		    !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
+		    !(flags & EXT4_GET_BLOCKS_ZERO) &&
+		    !ext4_is_quota_file(inode) &&
+		    ext4_should_order_data(inode)) {
+			loff_t start_byte =
+				(loff_t)map->m_lblk << inode->i_blkbits;
+			loff_t length = (loff_t)map->m_len << inode->i_blkbits;
+
+			if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
+				ret = ext4_jbd2_inode_add_wait(handle, inode,
+						start_byte, length);
+			else
+				ret = ext4_jbd2_inode_add_write(handle, inode,
+						start_byte, length);
+			if (ret)
+				return ret;
+		}
+	}
+	if (retval > 0 && (map->m_flags & EXT4_MAP_UNWRITTEN ||
+				map->m_flags & EXT4_MAP_MAPPED))
+		ext4_fc_track_range(handle, inode, map->m_lblk,
+					map->m_lblk + map->m_len - 1);
+	if (retval < 0)
+		ext_debug(inode, "failed with err %d\n", retval);
+	return retval;
+}
+
+/*
+ * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
+ * we have to be careful as someone else may be manipulating b_state as well.
+ */
+static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
+{
+	unsigned long old_state;
+	unsigned long new_state;
+
+	flags &= EXT4_MAP_FLAGS;
+
+	/* Dummy buffer_head? Set non-atomically. */
+	if (!bh->b_page) {
+		bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
+		return;
+	}
+	/*
+	 * Someone else may be modifying b_state. Be careful! This is ugly but
+	 * once we get rid of using bh as a container for mapping information
+	 * to pass to / from get_block functions, this can go away.
+	 */
+	do {
+		old_state = READ_ONCE(bh->b_state);
+		new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
+	} while (unlikely(
+		 cmpxchg(&bh->b_state, old_state, new_state) != old_state));
+}
+
+static int _ext4_get_block(struct inode *inode, sector_t iblock,
+			   struct buffer_head *bh, int flags)
+{
+	struct ext4_map_blocks map;
+	int ret = 0;
+
+	if (ext4_has_inline_data(inode))
+		return -ERANGE;
+
+	map.m_lblk = iblock;
+	map.m_len = bh->b_size >> inode->i_blkbits;
+
+	ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
+			      flags);
+	if (ret > 0) {
+		map_bh(bh, inode->i_sb, map.m_pblk);
+		ext4_update_bh_state(bh, map.m_flags);
+		bh->b_size = inode->i_sb->s_blocksize * map.m_len;
+		ret = 0;
+	} else if (ret == 0) {
+		/* hole case, need to fill in bh->b_size */
+		bh->b_size = inode->i_sb->s_blocksize * map.m_len;
+	}
+	return ret;
+}
+
+int ext4_get_block(struct inode *inode, sector_t iblock,
+		   struct buffer_head *bh, int create)
+{
+	return _ext4_get_block(inode, iblock, bh,
+			       create ? EXT4_GET_BLOCKS_CREATE : 0);
+}
+
+/*
+ * Get block function used when preparing for buffered write if we require
+ * creating an unwritten extent if blocks haven't been allocated.  The extent
+ * will be converted to written after the IO is complete.
+ */
+int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
+			     struct buffer_head *bh_result, int create)
+{
+	ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
+		   inode->i_ino, create);
+	return _ext4_get_block(inode, iblock, bh_result,
+			       EXT4_GET_BLOCKS_IO_CREATE_EXT);
+}
+
+/* Maximum number of blocks we map for direct IO at once. */
+#define DIO_MAX_BLOCKS 4096
+
+/*
+ * `handle' can be NULL if create is zero
+ */
+struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
+				ext4_lblk_t block, int map_flags)
+{
+	struct ext4_map_blocks map;
+	struct buffer_head *bh;
+	int create = map_flags & EXT4_GET_BLOCKS_CREATE;
+	int err;
+
+	J_ASSERT((EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		 || handle != NULL || create == 0);
+
+	map.m_lblk = block;
+	map.m_len = 1;
+	err = ext4_map_blocks(handle, inode, &map, map_flags);
+
+	if (err == 0)
+		return create ? ERR_PTR(-ENOSPC) : NULL;
+	if (err < 0)
+		return ERR_PTR(err);
+
+	bh = sb_getblk(inode->i_sb, map.m_pblk);
+	if (unlikely(!bh))
+		return ERR_PTR(-ENOMEM);
+	if (map.m_flags & EXT4_MAP_NEW) {
+		J_ASSERT(create != 0);
+		J_ASSERT((EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+			 || (handle != NULL));
+
+		/*
+		 * Now that we do not always journal data, we should
+		 * keep in mind whether this should always journal the
+		 * new buffer as metadata.  For now, regular file
+		 * writes use ext4_get_block instead, so it's not a
+		 * problem.
+		 */
+		lock_buffer(bh);
+		BUFFER_TRACE(bh, "call get_create_access");
+		err = ext4_journal_get_create_access(handle, bh);
+		if (unlikely(err)) {
+			unlock_buffer(bh);
+			goto errout;
+		}
+		if (!buffer_uptodate(bh)) {
+			memset(bh->b_data, 0, inode->i_sb->s_blocksize);
+			set_buffer_uptodate(bh);
+		}
+		unlock_buffer(bh);
+		BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
+		err = ext4_handle_dirty_metadata(handle, inode, bh);
+		if (unlikely(err))
+			goto errout;
+	} else
+		BUFFER_TRACE(bh, "not a new buffer");
+	return bh;
+errout:
+	brelse(bh);
+	return ERR_PTR(err);
+}
+
+struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
+			       ext4_lblk_t block, int map_flags)
+{
+	struct buffer_head *bh;
+	int ret;
+
+	bh = ext4_getblk(handle, inode, block, map_flags);
+	if (IS_ERR(bh))
+		return bh;
+	if (!bh || ext4_buffer_uptodate(bh))
+		return bh;
+
+	ret = ext4_read_bh_lock(bh, REQ_META | REQ_PRIO, true);
+	if (ret) {
+		put_bh(bh);
+		return ERR_PTR(ret);
+	}
+	return bh;
+}
+
+/* Read a contiguous batch of blocks. */
+int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
+		     bool wait, struct buffer_head **bhs)
+{
+	int i, err;
+
+	for (i = 0; i < bh_count; i++) {
+		bhs[i] = ext4_getblk(NULL, inode, block + i, 0 /* map_flags */);
+		if (IS_ERR(bhs[i])) {
+			err = PTR_ERR(bhs[i]);
+			bh_count = i;
+			goto out_brelse;
+		}
+	}
+
+	for (i = 0; i < bh_count; i++)
+		/* Note that NULL bhs[i] is valid because of holes. */
+		if (bhs[i] && !ext4_buffer_uptodate(bhs[i]))
+			ext4_read_bh_lock(bhs[i], REQ_META | REQ_PRIO, false);
+
+	if (!wait)
+		return 0;
+
+	for (i = 0; i < bh_count; i++)
+		if (bhs[i])
+			wait_on_buffer(bhs[i]);
+
+	for (i = 0; i < bh_count; i++) {
+		if (bhs[i] && !buffer_uptodate(bhs[i])) {
+			err = -EIO;
+			goto out_brelse;
+		}
+	}
+	return 0;
+
+out_brelse:
+	for (i = 0; i < bh_count; i++) {
+		brelse(bhs[i]);
+		bhs[i] = NULL;
+	}
+	return err;
+}
+
+int ext4_walk_page_buffers(handle_t *handle,
+			   struct buffer_head *head,
+			   unsigned from,
+			   unsigned to,
+			   int *partial,
+			   int (*fn)(handle_t *handle,
+				     struct buffer_head *bh))
+{
+	struct buffer_head *bh;
+	unsigned block_start, block_end;
+	unsigned blocksize = head->b_size;
+	int err, ret = 0;
+	struct buffer_head *next;
+
+	for (bh = head, block_start = 0;
+	     ret == 0 && (bh != head || !block_start);
+	     block_start = block_end, bh = next) {
+		next = bh->b_this_page;
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (partial && !buffer_uptodate(bh))
+				*partial = 1;
+			continue;
+		}
+		err = (*fn)(handle, bh);
+		if (!ret)
+			ret = err;
+	}
+	return ret;
+}
+
+/*
+ * To preserve ordering, it is essential that the hole instantiation and
+ * the data write be encapsulated in a single transaction.  We cannot
+ * close off a transaction and start a new one between the ext4_get_block()
+ * and the commit_write().  So doing the jbd2_journal_start at the start of
+ * prepare_write() is the right place.
+ *
+ * Also, this function can nest inside ext4_writepage().  In that case, we
+ * *know* that ext4_writepage() has generated enough buffer credits to do the
+ * whole page.  So we won't block on the journal in that case, which is good,
+ * because the caller may be PF_MEMALLOC.
+ *
+ * By accident, ext4 can be reentered when a transaction is open via
+ * quota file writes.  If we were to commit the transaction while thus
+ * reentered, there can be a deadlock - we would be holding a quota
+ * lock, and the commit would never complete if another thread had a
+ * transaction open and was blocking on the quota lock - a ranking
+ * violation.
+ *
+ * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
+ * will _not_ run commit under these circumstances because handle->h_ref
+ * is elevated.  We'll still have enough credits for the tiny quotafile
+ * write.
+ */
+int do_journal_get_write_access(handle_t *handle,
+				struct buffer_head *bh)
+{
+	int dirty = buffer_dirty(bh);
+	int ret;
+
+	if (!buffer_mapped(bh) || buffer_freed(bh))
+		return 0;
+	/*
+	 * __block_write_begin() could have dirtied some buffers. Clean
+	 * the dirty bit as jbd2_journal_get_write_access() could complain
+	 * otherwise about fs integrity issues. Setting of the dirty bit
+	 * by __block_write_begin() isn't a real problem here as we clear
+	 * the bit before releasing a page lock and thus writeback cannot
+	 * ever write the buffer.
+	 */
+	if (dirty)
+		clear_buffer_dirty(bh);
+	BUFFER_TRACE(bh, "get write access");
+	ret = ext4_journal_get_write_access(handle, bh);
+	if (!ret && dirty)
+		ret = ext4_handle_dirty_metadata(handle, NULL, bh);
+	return ret;
+}
+
+#ifdef CONFIG_FS_ENCRYPTION
+static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
+				  get_block_t *get_block)
+{
+	unsigned from = pos & (PAGE_SIZE - 1);
+	unsigned to = from + len;
+	struct inode *inode = page->mapping->host;
+	unsigned block_start, block_end;
+	sector_t block;
+	int err = 0;
+	unsigned blocksize = inode->i_sb->s_blocksize;
+	unsigned bbits;
+	struct buffer_head *bh, *head, *wait[2];
+	int nr_wait = 0;
+	int i;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(from > PAGE_SIZE);
+	BUG_ON(to > PAGE_SIZE);
+	BUG_ON(from > to);
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+	head = page_buffers(page);
+	bbits = ilog2(blocksize);
+	block = (sector_t)page->index << (PAGE_SHIFT - bbits);
+
+	for (bh = head, block_start = 0; bh != head || !block_start;
+	    block++, block_start = block_end, bh = bh->b_this_page) {
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (PageUptodate(page)) {
+				if (!buffer_uptodate(bh))
+					set_buffer_uptodate(bh);
+			}
+			continue;
+		}
+		if (buffer_new(bh))
+			clear_buffer_new(bh);
+		if (!buffer_mapped(bh)) {
+			WARN_ON(bh->b_size != blocksize);
+			err = get_block(inode, block, bh, 1);
+			if (err)
+				break;
+			if (buffer_new(bh)) {
+				if (PageUptodate(page)) {
+					clear_buffer_new(bh);
+					set_buffer_uptodate(bh);
+					mark_buffer_dirty(bh);
+					continue;
+				}
+				if (block_end > to || block_start < from)
+					zero_user_segments(page, to, block_end,
+							   block_start, from);
+				continue;
+			}
+		}
+		if (PageUptodate(page)) {
+			if (!buffer_uptodate(bh))
+				set_buffer_uptodate(bh);
+			continue;
+		}
+		if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
+		    !buffer_unwritten(bh) &&
+		    (block_start < from || block_end > to)) {
+			ext4_read_bh_lock(bh, 0, false);
+			wait[nr_wait++] = bh;
+		}
+	}
+	/*
+	 * If we issued read requests, let them complete.
+	 */
+	for (i = 0; i < nr_wait; i++) {
+		wait_on_buffer(wait[i]);
+		if (!buffer_uptodate(wait[i]))
+			err = -EIO;
+	}
+	if (unlikely(err)) {
+		page_zero_new_buffers(page, from, to);
+	} else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
+		for (i = 0; i < nr_wait; i++) {
+			int err2;
+
+			err2 = fscrypt_decrypt_pagecache_blocks(page, blocksize,
+								bh_offset(wait[i]));
+			if (err2) {
+				clear_buffer_uptodate(wait[i]);
+				err = err2;
+			}
+		}
+	}
+
+	return err;
+}
+#endif
+
+static int ext4_write_begin(struct file *file, struct address_space *mapping,
+			    loff_t pos, unsigned len, unsigned flags,
+			    struct page **pagep, void **fsdata)
+{
+	struct inode *inode = mapping->host;
+	int ret, needed_blocks;
+	handle_t *handle;
+	int retries = 0;
+	struct page *page;
+	pgoff_t index;
+	unsigned from, to;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	trace_ext4_write_begin(inode, pos, len, flags);
+	/*
+	 * Reserve one block more for addition to orphan list in case
+	 * we allocate blocks but write fails for some reason
+	 */
+	needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
+	index = pos >> PAGE_SHIFT;
+	from = pos & (PAGE_SIZE - 1);
+	to = from + len;
+
+	if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
+		ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
+						    flags, pagep);
+		if (ret < 0)
+			return ret;
+		if (ret == 1)
+			return 0;
+	}
+
+	/*
+	 * grab_cache_page_write_begin() can take a long time if the
+	 * system is thrashing due to memory pressure, or if the page
+	 * is being written back.  So grab it first before we start
+	 * the transaction handle.  This also allows us to allocate
+	 * the page (if needed) without using GFP_NOFS.
+	 */
+retry_grab:
+	page = grab_cache_page_write_begin(mapping, index, flags);
+	if (!page)
+		return -ENOMEM;
+	/*
+	 * The same as page allocation, we prealloc buffer heads before
+	 * starting the handle.
+	 */
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, inode->i_sb->s_blocksize, 0);
+
+	unlock_page(page);
+
+retry_journal:
+	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
+	if (IS_ERR(handle)) {
+		put_page(page);
+		return PTR_ERR(handle);
+	}
+
+	lock_page(page);
+	if (page->mapping != mapping) {
+		/* The page got truncated from under us */
+		unlock_page(page);
+		put_page(page);
+		ext4_journal_stop(handle);
+		goto retry_grab;
+	}
+	/* In case writeback began while the page was unlocked */
+	wait_for_stable_page(page);
+
+#ifdef CONFIG_FS_ENCRYPTION
+	if (ext4_should_dioread_nolock(inode))
+		ret = ext4_block_write_begin(page, pos, len,
+					     ext4_get_block_unwritten);
+	else
+		ret = ext4_block_write_begin(page, pos, len,
+					     ext4_get_block);
+#else
+	if (ext4_should_dioread_nolock(inode))
+		ret = __block_write_begin(page, pos, len,
+					  ext4_get_block_unwritten);
+	else
+		ret = __block_write_begin(page, pos, len, ext4_get_block);
+#endif
+	if (!ret && ext4_should_journal_data(inode)) {
+		ret = ext4_walk_page_buffers(handle, page_buffers(page),
+					     from, to, NULL,
+					     do_journal_get_write_access);
+	}
+
+	if (ret) {
+		bool extended = (pos + len > inode->i_size) &&
+				!ext4_verity_in_progress(inode);
+
+		unlock_page(page);
+		/*
+		 * __block_write_begin may have instantiated a few blocks
+		 * outside i_size.  Trim these off again. Don't need
+		 * i_size_read because we hold i_mutex.
+		 *
+		 * Add inode to orphan list in case we crash before
+		 * truncate finishes
+		 */
+		if (extended && ext4_can_truncate(inode))
+			ext4_orphan_add(handle, inode);
+
+		ext4_journal_stop(handle);
+		if (extended) {
+			ext4_truncate_failed_write(inode);
+			/*
+			 * If truncate failed early the inode might
+			 * still be on the orphan list; we need to
+			 * make sure the inode is removed from the
+			 * orphan list in that case.
+			 */
+			if (inode->i_nlink)
+				ext4_orphan_del(NULL, inode);
+		}
+
+		if (ret == -ENOSPC &&
+		    ext4_should_retry_alloc(inode->i_sb, &retries))
+			goto retry_journal;
+		put_page(page);
+		return ret;
+	}
+	*pagep = page;
+	return ret;
+}
+
+/* For write_end() in data=journal mode */
+static int write_end_fn(handle_t *handle, struct buffer_head *bh)
+{
+	int ret;
+	if (!buffer_mapped(bh) || buffer_freed(bh))
+		return 0;
+	set_buffer_uptodate(bh);
+	ret = ext4_handle_dirty_metadata(handle, NULL, bh);
+	clear_buffer_meta(bh);
+	clear_buffer_prio(bh);
+	return ret;
+}
+
+/*
+ * We need to pick up the new inode size which generic_commit_write gave us
+ * `file' can be NULL - eg, when called from page_symlink().
+ *
+ * ext4 never places buffers on inode->i_mapping->private_list.  metadata
+ * buffers are managed internally.
+ */
+static int ext4_write_end(struct file *file,
+			  struct address_space *mapping,
+			  loff_t pos, unsigned len, unsigned copied,
+			  struct page *page, void *fsdata)
+{
+	handle_t *handle = ext4_journal_current_handle();
+	struct inode *inode = mapping->host;
+	loff_t old_size = inode->i_size;
+	int ret = 0, ret2;
+	int i_size_changed = 0;
+	int inline_data = ext4_has_inline_data(inode);
+	bool verity = ext4_verity_in_progress(inode);
+
+	trace_ext4_write_end(inode, pos, len, copied);
+	if (inline_data &&
+	    ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
+		ret = ext4_write_inline_data_end(inode, pos, len,
+						 copied, page);
+		if (ret < 0) {
+			unlock_page(page);
+			put_page(page);
+			goto errout;
+		}
+		copied = ret;
+		ret = 0;
+	} else
+		copied = block_write_end(file, mapping, pos,
+					 len, copied, page, fsdata);
+	/*
+	 * it's important to update i_size while still holding page lock:
+	 * page writeout could otherwise come in and zero beyond i_size.
+	 *
+	 * If FS_IOC_ENABLE_VERITY is running on this inode, then Merkle tree
+	 * blocks are being written past EOF, so skip the i_size update.
+	 */
+	if (!verity)
+		i_size_changed = ext4_update_inode_size(inode, pos + copied);
+	unlock_page(page);
+	put_page(page);
+
+	if (old_size < pos && !verity)
+		pagecache_isize_extended(inode, old_size, pos);
+	/*
+	 * Don't mark the inode dirty under page lock. First, it unnecessarily
+	 * makes the holding time of page lock longer. Second, it forces lock
+	 * ordering of page lock and transaction start for journaling
+	 * filesystems.
+	 */
+	if (i_size_changed || inline_data)
+		ret = ext4_mark_inode_dirty(handle, inode);
+
+errout:
+	if (pos + len > inode->i_size && !verity && ext4_can_truncate(inode))
+		/* if we have allocated more blocks and copied
+		 * less. We will have blocks allocated outside
+		 * inode->i_size. So truncate them
+		 */
+		ext4_orphan_add(handle, inode);
+
+	ret2 = ext4_journal_stop(handle);
+	if (!ret)
+		ret = ret2;
+
+	if (pos + len > inode->i_size && !verity) {
+		ext4_truncate_failed_write(inode);
+		/*
+		 * If truncate failed early the inode might still be
+		 * on the orphan list; we need to make sure the inode
+		 * is removed from the orphan list in that case.
+		 */
+		if (inode->i_nlink)
+			ext4_orphan_del(NULL, inode);
+	}
+
+	return ret ? ret : copied;
+}
+
+/*
+ * This is a private version of page_zero_new_buffers() which doesn't
+ * set the buffer to be dirty, since in data=journalled mode we need
+ * to call ext4_handle_dirty_metadata() instead.
+ */
+static void ext4_journalled_zero_new_buffers(handle_t *handle,
+					    struct page *page,
+					    unsigned from, unsigned to)
+{
+	unsigned int block_start = 0, block_end;
+	struct buffer_head *head, *bh;
+
+	bh = head = page_buffers(page);
+	do {
+		block_end = block_start + bh->b_size;
+		if (buffer_new(bh)) {
+			if (block_end > from && block_start < to) {
+				if (!PageUptodate(page)) {
+					unsigned start, size;
+
+					start = max(from, block_start);
+					size = min(to, block_end) - start;
+
+					zero_user(page, start, size);
+					write_end_fn(handle, bh);
+				}
+				clear_buffer_new(bh);
+			}
+		}
+		block_start = block_end;
+		bh = bh->b_this_page;
+	} while (bh != head);
+}
+
+static int ext4_journalled_write_end(struct file *file,
+				     struct address_space *mapping,
+				     loff_t pos, unsigned len, unsigned copied,
+				     struct page *page, void *fsdata)
+{
+	handle_t *handle = ext4_journal_current_handle();
+	struct inode *inode = mapping->host;
+	loff_t old_size = inode->i_size;
+	int ret = 0, ret2;
+	int partial = 0;
+	unsigned from, to;
+	int size_changed = 0;
+	int inline_data = ext4_has_inline_data(inode);
+	bool verity = ext4_verity_in_progress(inode);
+
+	trace_ext4_journalled_write_end(inode, pos, len, copied);
+	from = pos & (PAGE_SIZE - 1);
+	to = from + len;
+
+	BUG_ON(!ext4_handle_valid(handle));
+
+	if (inline_data) {
+		ret = ext4_write_inline_data_end(inode, pos, len,
+						 copied, page);
+		if (ret < 0) {
+			unlock_page(page);
+			put_page(page);
+			goto errout;
+		}
+		copied = ret;
+		ret = 0;
+	} else if (unlikely(copied < len) && !PageUptodate(page)) {
+		copied = 0;
+		ext4_journalled_zero_new_buffers(handle, page, from, to);
+	} else {
+		if (unlikely(copied < len))
+			ext4_journalled_zero_new_buffers(handle, page,
+							 from + copied, to);
+		ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
+					     from + copied, &partial,
+					     write_end_fn);
+		if (!partial)
+			SetPageUptodate(page);
+	}
+	if (!verity)
+		size_changed = ext4_update_inode_size(inode, pos + copied);
+	ext4_set_inode_state(inode, EXT4_STATE_JDATA);
+	EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
+	unlock_page(page);
+	put_page(page);
+
+	if (old_size < pos && !verity)
+		pagecache_isize_extended(inode, old_size, pos);
+
+	if (size_changed || inline_data) {
+		ret2 = ext4_mark_inode_dirty(handle, inode);
+		if (!ret)
+			ret = ret2;
+	}
+
+errout:
+	if (pos + len > inode->i_size && !verity && ext4_can_truncate(inode))
+		/* if we have allocated more blocks and copied
+		 * less. We will have blocks allocated outside
+		 * inode->i_size. So truncate them
+		 */
+		ext4_orphan_add(handle, inode);
+
+	ret2 = ext4_journal_stop(handle);
+	if (!ret)
+		ret = ret2;
+	if (pos + len > inode->i_size && !verity) {
+		ext4_truncate_failed_write(inode);
+		/*
+		 * If truncate failed early the inode might still be
+		 * on the orphan list; we need to make sure the inode
+		 * is removed from the orphan list in that case.
+		 */
+		if (inode->i_nlink)
+			ext4_orphan_del(NULL, inode);
+	}
+
+	return ret ? ret : copied;
+}
+
+/*
+ * Reserve space for a single cluster
+ */
+static int ext4_da_reserve_space(struct inode *inode)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	int ret;
+
+	/*
+	 * We will charge metadata quota at writeout time; this saves
+	 * us from metadata over-estimation, though we may go over by
+	 * a small amount in the end.  Here we just reserve for data.
+	 */
+	ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
+	if (ret)
+		return ret;
+
+	spin_lock(&ei->i_block_reservation_lock);
+	if (ext4_claim_free_clusters(sbi, 1, 0)) {
+		spin_unlock(&ei->i_block_reservation_lock);
+		dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
+		return -ENOSPC;
+	}
+	ei->i_reserved_data_blocks++;
+	trace_ext4_da_reserve_space(inode);
+	spin_unlock(&ei->i_block_reservation_lock);
+
+	return 0;       /* success */
+}
+
+void ext4_da_release_space(struct inode *inode, int to_free)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct ext4_inode_info *ei = EXT4_I(inode);
+
+	if (!to_free)
+		return;		/* Nothing to release, exit */
+
+	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
+
+	trace_ext4_da_release_space(inode, to_free);
+	if (unlikely(to_free > ei->i_reserved_data_blocks)) {
+		/*
+		 * if there aren't enough reserved blocks, then the
+		 * counter is messed up somewhere.  Since this
+		 * function is called from invalidate page, it's
+		 * harmless to return without any action.
+		 */
+		ext4_warning(inode->i_sb, "ext4_da_release_space: "
+			 "ino %lu, to_free %d with only %d reserved "
+			 "data blocks", inode->i_ino, to_free,
+			 ei->i_reserved_data_blocks);
+		WARN_ON(1);
+		to_free = ei->i_reserved_data_blocks;
+	}
+	ei->i_reserved_data_blocks -= to_free;
+
+	/* update fs dirty data blocks counter */
+	percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
+
+	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+
+	dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
+}
+
+/*
+ * Delayed allocation stuff
+ */
+
+struct mpage_da_data {
+	struct inode *inode;
+	struct writeback_control *wbc;
+
+	pgoff_t first_page;	/* The first page to write */
+	pgoff_t next_page;	/* Current page to examine */
+	pgoff_t last_page;	/* Last page to examine */
+	/*
+	 * Extent to map - this can be after first_page because that can be
+	 * fully mapped. We somewhat abuse m_flags to store whether the extent
+	 * is delalloc or unwritten.
+	 */
+	struct ext4_map_blocks map;
+	struct ext4_io_submit io_submit;	/* IO submission data */
+	unsigned int do_map:1;
+	unsigned int scanned_until_end:1;
+};
+
+static void mpage_release_unused_pages(struct mpage_da_data *mpd,
+				       bool invalidate)
+{
+	int nr_pages, i;
+	pgoff_t index, end;
+	struct pagevec pvec;
+	struct inode *inode = mpd->inode;
+	struct address_space *mapping = inode->i_mapping;
+
+	/* This is necessary when next_page == 0. */
+	if (mpd->first_page >= mpd->next_page)
+		return;
+
+	mpd->scanned_until_end = 0;
+	index = mpd->first_page;
+	end   = mpd->next_page - 1;
+	if (invalidate) {
+		ext4_lblk_t start, last;
+		start = index << (PAGE_SHIFT - inode->i_blkbits);
+		last = end << (PAGE_SHIFT - inode->i_blkbits);
+
+		/*
+		 * avoid racing with extent status tree scans made by
+		 * ext4_insert_delayed_block()
+		 */
+		down_write(&EXT4_I(inode)->i_data_sem);
+		ext4_es_remove_extent(inode, start, last - start + 1);
+		up_write(&EXT4_I(inode)->i_data_sem);
+	}
+
+	pagevec_init(&pvec);
+	while (index <= end) {
+		nr_pages = pagevec_lookup_range(&pvec, mapping, &index, end);
+		if (nr_pages == 0)
+			break;
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			BUG_ON(!PageLocked(page));
+			BUG_ON(PageWriteback(page));
+			if (invalidate) {
+				if (page_mapped(page))
+					clear_page_dirty_for_io(page);
+				block_invalidatepage(page, 0, PAGE_SIZE);
+				ClearPageUptodate(page);
+			}
+			unlock_page(page);
+		}
+		pagevec_release(&pvec);
+	}
+}
+
+static void ext4_print_free_blocks(struct inode *inode)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct super_block *sb = inode->i_sb;
+	struct ext4_inode_info *ei = EXT4_I(inode);
+
+	ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
+	       EXT4_C2B(EXT4_SB(inode->i_sb),
+			ext4_count_free_clusters(sb)));
+	ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
+	ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
+	       (long long) EXT4_C2B(EXT4_SB(sb),
+		percpu_counter_sum(&sbi->s_freeclusters_counter)));
+	ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
+	       (long long) EXT4_C2B(EXT4_SB(sb),
+		percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
+	ext4_msg(sb, KERN_CRIT, "Block reservation details");
+	ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
+		 ei->i_reserved_data_blocks);
+	return;
+}
+
+static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
+{
+	return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
+}
+
+/*
+ * ext4_insert_delayed_block - adds a delayed block to the extents status
+ *                             tree, incrementing the reserved cluster/block
+ *                             count or making a pending reservation
+ *                             where needed
+ *
+ * @inode - file containing the newly added block
+ * @lblk - logical block to be added
+ *
+ * Returns 0 on success, negative error code on failure.
+ */
+static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	int ret;
+	bool allocated = false;
+	bool reserved = false;
+
+	/*
+	 * If the cluster containing lblk is shared with a delayed,
+	 * written, or unwritten extent in a bigalloc file system, it's
+	 * already been accounted for and does not need to be reserved.
+	 * A pending reservation must be made for the cluster if it's
+	 * shared with a written or unwritten extent and doesn't already
+	 * have one.  Written and unwritten extents can be purged from the
+	 * extents status tree if the system is under memory pressure, so
+	 * it's necessary to examine the extent tree if a search of the
+	 * extents status tree doesn't get a match.
+	 */
+	if (sbi->s_cluster_ratio == 1) {
+		ret = ext4_da_reserve_space(inode);
+		if (ret != 0)   /* ENOSPC */
+			goto errout;
+		reserved = true;
+	} else {   /* bigalloc */
+		if (!ext4_es_scan_clu(inode, &ext4_es_is_delonly, lblk)) {
+			if (!ext4_es_scan_clu(inode,
+					      &ext4_es_is_mapped, lblk)) {
+				ret = ext4_clu_mapped(inode,
+						      EXT4_B2C(sbi, lblk));
+				if (ret < 0)
+					goto errout;
+				if (ret == 0) {
+					ret = ext4_da_reserve_space(inode);
+					if (ret != 0)   /* ENOSPC */
+						goto errout;
+					reserved = true;
+				} else {
+					allocated = true;
+				}
+			} else {
+				allocated = true;
+			}
+		}
+	}
+
+	ret = ext4_es_insert_delayed_block(inode, lblk, allocated);
+	if (ret && reserved)
+		ext4_da_release_space(inode, 1);
+
+errout:
+	return ret;
+}
+
+/*
+ * This function is grabs code from the very beginning of
+ * ext4_map_blocks, but assumes that the caller is from delayed write
+ * time. This function looks up the requested blocks and sets the
+ * buffer delay bit under the protection of i_data_sem.
+ */
+static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
+			      struct ext4_map_blocks *map,
+			      struct buffer_head *bh)
+{
+	struct extent_status es;
+	int retval;
+	sector_t invalid_block = ~((sector_t) 0xffff);
+#ifdef ES_AGGRESSIVE_TEST
+	struct ext4_map_blocks orig_map;
+
+	memcpy(&orig_map, map, sizeof(*map));
+#endif
+
+	if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
+		invalid_block = ~0;
+
+	map->m_flags = 0;
+	ext_debug(inode, "max_blocks %u, logical block %lu\n", map->m_len,
+		  (unsigned long) map->m_lblk);
+
+	/* Lookup extent status tree firstly */
+	if (ext4_es_lookup_extent(inode, iblock, NULL, &es)) {
+		if (ext4_es_is_hole(&es)) {
+			retval = 0;
+			down_read(&EXT4_I(inode)->i_data_sem);
+			goto add_delayed;
+		}
+
+		/*
+		 * Delayed extent could be allocated by fallocate.
+		 * So we need to check it.
+		 */
+		if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
+			map_bh(bh, inode->i_sb, invalid_block);
+			set_buffer_new(bh);
+			set_buffer_delay(bh);
+			return 0;
+		}
+
+		map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
+		retval = es.es_len - (iblock - es.es_lblk);
+		if (retval > map->m_len)
+			retval = map->m_len;
+		map->m_len = retval;
+		if (ext4_es_is_written(&es))
+			map->m_flags |= EXT4_MAP_MAPPED;
+		else if (ext4_es_is_unwritten(&es))
+			map->m_flags |= EXT4_MAP_UNWRITTEN;
+		else
+			BUG();
+
+#ifdef ES_AGGRESSIVE_TEST
+		ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
+#endif
+		return retval;
+	}
+
+	/*
+	 * Try to see if we can get the block without requesting a new
+	 * file system block.
+	 */
+	down_read(&EXT4_I(inode)->i_data_sem);
+	if (ext4_has_inline_data(inode))
+		retval = 0;
+	else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		retval = ext4_ext_map_blocks(NULL, inode, map, 0);
+	else
+		retval = ext4_ind_map_blocks(NULL, inode, map, 0);
+
+add_delayed:
+	if (retval == 0) {
+		int ret;
+
+		/*
+		 * XXX: __block_prepare_write() unmaps passed block,
+		 * is it OK?
+		 */
+
+		ret = ext4_insert_delayed_block(inode, map->m_lblk);
+		if (ret != 0) {
+			retval = ret;
+			goto out_unlock;
+		}
+
+		map_bh(bh, inode->i_sb, invalid_block);
+		set_buffer_new(bh);
+		set_buffer_delay(bh);
+	} else if (retval > 0) {
+		int ret;
+		unsigned int status;
+
+		if (unlikely(retval != map->m_len)) {
+			ext4_warning(inode->i_sb,
+				     "ES len assertion failed for inode "
+				     "%lu: retval %d != map->m_len %d",
+				     inode->i_ino, retval, map->m_len);
+			WARN_ON(1);
+		}
+
+		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
+				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
+		ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
+					    map->m_pblk, status);
+		if (ret != 0)
+			retval = ret;
+	}
+
+out_unlock:
+	up_read((&EXT4_I(inode)->i_data_sem));
+
+	return retval;
+}
+
+/*
+ * This is a special get_block_t callback which is used by
+ * ext4_da_write_begin().  It will either return mapped block or
+ * reserve space for a single block.
+ *
+ * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
+ * We also have b_blocknr = -1 and b_bdev initialized properly
+ *
+ * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
+ * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
+ * initialized properly.
+ */
+int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
+			   struct buffer_head *bh, int create)
+{
+	struct ext4_map_blocks map;
+	int ret = 0;
+
+	BUG_ON(create == 0);
+	BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
+
+	map.m_lblk = iblock;
+	map.m_len = 1;
+
+	/*
+	 * first, we need to know whether the block is allocated already
+	 * preallocated blocks are unmapped but should treated
+	 * the same as allocated blocks.
+	 */
+	ret = ext4_da_map_blocks(inode, iblock, &map, bh);
+	if (ret <= 0)
+		return ret;
+
+	map_bh(bh, inode->i_sb, map.m_pblk);
+	ext4_update_bh_state(bh, map.m_flags);
+
+	if (buffer_unwritten(bh)) {
+		/* A delayed write to unwritten bh should be marked
+		 * new and mapped.  Mapped ensures that we don't do
+		 * get_block multiple times when we write to the same
+		 * offset and new ensures that we do proper zero out
+		 * for partial write.
+		 */
+		set_buffer_new(bh);
+		set_buffer_mapped(bh);
+	}
+	return 0;
+}
+
+static int bget_one(handle_t *handle, struct buffer_head *bh)
+{
+	get_bh(bh);
+	return 0;
+}
+
+static int bput_one(handle_t *handle, struct buffer_head *bh)
+{
+	put_bh(bh);
+	return 0;
+}
+
+static int __ext4_journalled_writepage(struct page *page,
+				       unsigned int len)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+	struct buffer_head *page_bufs = NULL;
+	handle_t *handle = NULL;
+	int ret = 0, err = 0;
+	int inline_data = ext4_has_inline_data(inode);
+	struct buffer_head *inode_bh = NULL;
+
+	ClearPageChecked(page);
+
+	if (inline_data) {
+		BUG_ON(page->index != 0);
+		BUG_ON(len > ext4_get_max_inline_size(inode));
+		inode_bh = ext4_journalled_write_inline_data(inode, len, page);
+		if (inode_bh == NULL)
+			goto out;
+	} else {
+		page_bufs = page_buffers(page);
+		if (!page_bufs) {
+			BUG();
+			goto out;
+		}
+		ext4_walk_page_buffers(handle, page_bufs, 0, len,
+				       NULL, bget_one);
+	}
+	/*
+	 * We need to release the page lock before we start the
+	 * journal, so grab a reference so the page won't disappear
+	 * out from under us.
+	 */
+	get_page(page);
+	unlock_page(page);
+
+	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
+				    ext4_writepage_trans_blocks(inode));
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		put_page(page);
+		goto out_no_pagelock;
+	}
+	BUG_ON(!ext4_handle_valid(handle));
+
+	lock_page(page);
+	put_page(page);
+	if (page->mapping != mapping) {
+		/* The page got truncated from under us */
+		ext4_journal_stop(handle);
+		ret = 0;
+		goto out;
+	}
+
+	if (inline_data) {
+		ret = ext4_mark_inode_dirty(handle, inode);
+	} else {
+		ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
+					     do_journal_get_write_access);
+
+		err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
+					     write_end_fn);
+	}
+	if (ret == 0)
+		ret = err;
+	err = ext4_jbd2_inode_add_write(handle, inode, page_offset(page), len);
+	if (ret == 0)
+		ret = err;
+	EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
+	err = ext4_journal_stop(handle);
+	if (!ret)
+		ret = err;
+
+	ext4_set_inode_state(inode, EXT4_STATE_JDATA);
+out:
+	unlock_page(page);
+out_no_pagelock:
+	if (!inline_data && page_bufs)
+		ext4_walk_page_buffers(NULL, page_bufs, 0, len,
+				       NULL, bput_one);
+	brelse(inode_bh);
+	return ret;
+}
+
+/*
+ * Note that we don't need to start a transaction unless we're journaling data
+ * because we should have holes filled from ext4_page_mkwrite(). We even don't
+ * need to file the inode to the transaction's list in ordered mode because if
+ * we are writing back data added by write(), the inode is already there and if
+ * we are writing back data modified via mmap(), no one guarantees in which
+ * transaction the data will hit the disk. In case we are journaling data, we
+ * cannot start transaction directly because transaction start ranks above page
+ * lock so we have to do some magic.
+ *
+ * This function can get called via...
+ *   - ext4_writepages after taking page lock (have journal handle)
+ *   - journal_submit_inode_data_buffers (no journal handle)
+ *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
+ *   - grab_page_cache when doing write_begin (have journal handle)
+ *
+ * We don't do any block allocation in this function. If we have page with
+ * multiple blocks we need to write those buffer_heads that are mapped. This
+ * is important for mmaped based write. So if we do with blocksize 1K
+ * truncate(f, 1024);
+ * a = mmap(f, 0, 4096);
+ * a[0] = 'a';
+ * truncate(f, 4096);
+ * we have in the page first buffer_head mapped via page_mkwrite call back
+ * but other buffer_heads would be unmapped but dirty (dirty done via the
+ * do_wp_page). So writepage should write the first block. If we modify
+ * the mmap area beyond 1024 we will again get a page_fault and the
+ * page_mkwrite callback will do the block allocation and mark the
+ * buffer_heads mapped.
+ *
+ * We redirty the page if we have any buffer_heads that is either delay or
+ * unwritten in the page.
+ *
+ * We can get recursively called as show below.
+ *
+ *	ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
+ *		ext4_writepage()
+ *
+ * But since we don't do any block allocation we should not deadlock.
+ * Page also have the dirty flag cleared so we don't get recurive page_lock.
+ */
+static int ext4_writepage(struct page *page,
+			  struct writeback_control *wbc)
+{
+	int ret = 0;
+	loff_t size;
+	unsigned int len;
+	struct buffer_head *page_bufs = NULL;
+	struct inode *inode = page->mapping->host;
+	struct ext4_io_submit io_submit;
+	bool keep_towrite = false;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
+		inode->i_mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
+		unlock_page(page);
+		return -EIO;
+	}
+
+	trace_ext4_writepage(page);
+	size = i_size_read(inode);
+	if (page->index == size >> PAGE_SHIFT &&
+	    !ext4_verity_in_progress(inode))
+		len = size & ~PAGE_MASK;
+	else
+		len = PAGE_SIZE;
+
+	/* Should never happen but for bugs in other kernel subsystems */
+	if (!page_has_buffers(page)) {
+		ext4_warning_inode(inode,
+		   "page %lu does not have buffers attached", page->index);
+		ClearPageDirty(page);
+		unlock_page(page);
+		return 0;
+	}
+
+	page_bufs = page_buffers(page);
+	/*
+	 * We cannot do block allocation or other extent handling in this
+	 * function. If there are buffers needing that, we have to redirty
+	 * the page. But we may reach here when we do a journal commit via
+	 * journal_submit_inode_data_buffers() and in that case we must write
+	 * allocated buffers to achieve data=ordered mode guarantees.
+	 *
+	 * Also, if there is only one buffer per page (the fs block
+	 * size == the page size), if one buffer needs block
+	 * allocation or needs to modify the extent tree to clear the
+	 * unwritten flag, we know that the page can't be written at
+	 * all, so we might as well refuse the write immediately.
+	 * Unfortunately if the block size != page size, we can't as
+	 * easily detect this case using ext4_walk_page_buffers(), but
+	 * for the extremely common case, this is an optimization that
+	 * skips a useless round trip through ext4_bio_write_page().
+	 */
+	if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
+				   ext4_bh_delay_or_unwritten)) {
+		redirty_page_for_writepage(wbc, page);
+		if ((current->flags & PF_MEMALLOC) ||
+		    (inode->i_sb->s_blocksize == PAGE_SIZE)) {
+			/*
+			 * For memory cleaning there's no point in writing only
+			 * some buffers. So just bail out. Warn if we came here
+			 * from direct reclaim.
+			 */
+			WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
+							== PF_MEMALLOC);
+			unlock_page(page);
+			return 0;
+		}
+		keep_towrite = true;
+	}
+
+	if (PageChecked(page) && ext4_should_journal_data(inode))
+		/*
+		 * It's mmapped pagecache.  Add buffers and journal it.  There
+		 * doesn't seem much point in redirtying the page here.
+		 */
+		return __ext4_journalled_writepage(page, len);
+
+	ext4_io_submit_init(&io_submit, wbc);
+	io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
+	if (!io_submit.io_end) {
+		redirty_page_for_writepage(wbc, page);
+		unlock_page(page);
+		return -ENOMEM;
+	}
+	ret = ext4_bio_write_page(&io_submit, page, len, wbc, keep_towrite);
+	ext4_io_submit(&io_submit);
+	/* Drop io_end reference we got from init */
+	ext4_put_io_end_defer(io_submit.io_end);
+	return ret;
+}
+
+static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
+{
+	int len;
+	loff_t size;
+	int err;
+
+	BUG_ON(page->index != mpd->first_page);
+	clear_page_dirty_for_io(page);
+	/*
+	 * We have to be very careful here!  Nothing protects writeback path
+	 * against i_size changes and the page can be writeably mapped into
+	 * page tables. So an application can be growing i_size and writing
+	 * data through mmap while writeback runs. clear_page_dirty_for_io()
+	 * write-protects our page in page tables and the page cannot get
+	 * written to again until we release page lock. So only after
+	 * clear_page_dirty_for_io() we are safe to sample i_size for
+	 * ext4_bio_write_page() to zero-out tail of the written page. We rely
+	 * on the barrier provided by TestClearPageDirty in
+	 * clear_page_dirty_for_io() to make sure i_size is really sampled only
+	 * after page tables are updated.
+	 */
+	size = i_size_read(mpd->inode);
+	if (page->index == size >> PAGE_SHIFT &&
+	    !ext4_verity_in_progress(mpd->inode))
+		len = size & ~PAGE_MASK;
+	else
+		len = PAGE_SIZE;
+	err = ext4_bio_write_page(&mpd->io_submit, page, len, mpd->wbc, false);
+	if (!err)
+		mpd->wbc->nr_to_write--;
+	mpd->first_page++;
+
+	return err;
+}
+
+#define BH_FLAGS (BIT(BH_Unwritten) | BIT(BH_Delay))
+
+/*
+ * mballoc gives us at most this number of blocks...
+ * XXX: That seems to be only a limitation of ext4_mb_normalize_request().
+ * The rest of mballoc seems to handle chunks up to full group size.
+ */
+#define MAX_WRITEPAGES_EXTENT_LEN 2048
+
+/*
+ * mpage_add_bh_to_extent - try to add bh to extent of blocks to map
+ *
+ * @mpd - extent of blocks
+ * @lblk - logical number of the block in the file
+ * @bh - buffer head we want to add to the extent
+ *
+ * The function is used to collect contig. blocks in the same state. If the
+ * buffer doesn't require mapping for writeback and we haven't started the
+ * extent of buffers to map yet, the function returns 'true' immediately - the
+ * caller can write the buffer right away. Otherwise the function returns true
+ * if the block has been added to the extent, false if the block couldn't be
+ * added.
+ */
+static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
+				   struct buffer_head *bh)
+{
+	struct ext4_map_blocks *map = &mpd->map;
+
+	/* Buffer that doesn't need mapping for writeback? */
+	if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
+	    (!buffer_delay(bh) && !buffer_unwritten(bh))) {
+		/* So far no extent to map => we write the buffer right away */
+		if (map->m_len == 0)
+			return true;
+		return false;
+	}
+
+	/* First block in the extent? */
+	if (map->m_len == 0) {
+		/* We cannot map unless handle is started... */
+		if (!mpd->do_map)
+			return false;
+		map->m_lblk = lblk;
+		map->m_len = 1;
+		map->m_flags = bh->b_state & BH_FLAGS;
+		return true;
+	}
+
+	/* Don't go larger than mballoc is willing to allocate */
+	if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
+		return false;
+
+	/* Can we merge the block to our big extent? */
+	if (lblk == map->m_lblk + map->m_len &&
+	    (bh->b_state & BH_FLAGS) == map->m_flags) {
+		map->m_len++;
+		return true;
+	}
+	return false;
+}
+
+/*
+ * mpage_process_page_bufs - submit page buffers for IO or add them to extent
+ *
+ * @mpd - extent of blocks for mapping
+ * @head - the first buffer in the page
+ * @bh - buffer we should start processing from
+ * @lblk - logical number of the block in the file corresponding to @bh
+ *
+ * Walk through page buffers from @bh upto @head (exclusive) and either submit
+ * the page for IO if all buffers in this page were mapped and there's no
+ * accumulated extent of buffers to map or add buffers in the page to the
+ * extent of buffers to map. The function returns 1 if the caller can continue
+ * by processing the next page, 0 if it should stop adding buffers to the
+ * extent to map because we cannot extend it anymore. It can also return value
+ * < 0 in case of error during IO submission.
+ */
+static int mpage_process_page_bufs(struct mpage_da_data *mpd,
+				   struct buffer_head *head,
+				   struct buffer_head *bh,
+				   ext4_lblk_t lblk)
+{
+	struct inode *inode = mpd->inode;
+	int err;
+	ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
+							>> inode->i_blkbits;
+
+	if (ext4_verity_in_progress(inode))
+		blocks = EXT_MAX_BLOCKS;
+
+	do {
+		BUG_ON(buffer_locked(bh));
+
+		if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
+			/* Found extent to map? */
+			if (mpd->map.m_len)
+				return 0;
+			/* Buffer needs mapping and handle is not started? */
+			if (!mpd->do_map)
+				return 0;
+			/* Everything mapped so far and we hit EOF */
+			break;
+		}
+	} while (lblk++, (bh = bh->b_this_page) != head);
+	/* So far everything mapped? Submit the page for IO. */
+	if (mpd->map.m_len == 0) {
+		err = mpage_submit_page(mpd, head->b_page);
+		if (err < 0)
+			return err;
+	}
+	if (lblk >= blocks) {
+		mpd->scanned_until_end = 1;
+		return 0;
+	}
+	return 1;
+}
+
+/*
+ * mpage_process_page - update page buffers corresponding to changed extent and
+ *		       may submit fully mapped page for IO
+ *
+ * @mpd		- description of extent to map, on return next extent to map
+ * @m_lblk	- logical block mapping.
+ * @m_pblk	- corresponding physical mapping.
+ * @map_bh	- determines on return whether this page requires any further
+ *		  mapping or not.
+ * Scan given page buffers corresponding to changed extent and update buffer
+ * state according to new extent state.
+ * We map delalloc buffers to their physical location, clear unwritten bits.
+ * If the given page is not fully mapped, we update @map to the next extent in
+ * the given page that needs mapping & return @map_bh as true.
+ */
+static int mpage_process_page(struct mpage_da_data *mpd, struct page *page,
+			      ext4_lblk_t *m_lblk, ext4_fsblk_t *m_pblk,
+			      bool *map_bh)
+{
+	struct buffer_head *head, *bh;
+	ext4_io_end_t *io_end = mpd->io_submit.io_end;
+	ext4_lblk_t lblk = *m_lblk;
+	ext4_fsblk_t pblock = *m_pblk;
+	int err = 0;
+	int blkbits = mpd->inode->i_blkbits;
+	ssize_t io_end_size = 0;
+	struct ext4_io_end_vec *io_end_vec = ext4_last_io_end_vec(io_end);
+
+	bh = head = page_buffers(page);
+	do {
+		if (lblk < mpd->map.m_lblk)
+			continue;
+		if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
+			/*
+			 * Buffer after end of mapped extent.
+			 * Find next buffer in the page to map.
+			 */
+			mpd->map.m_len = 0;
+			mpd->map.m_flags = 0;
+			io_end_vec->size += io_end_size;
+			io_end_size = 0;
+
+			err = mpage_process_page_bufs(mpd, head, bh, lblk);
+			if (err > 0)
+				err = 0;
+			if (!err && mpd->map.m_len && mpd->map.m_lblk > lblk) {
+				io_end_vec = ext4_alloc_io_end_vec(io_end);
+				if (IS_ERR(io_end_vec)) {
+					err = PTR_ERR(io_end_vec);
+					goto out;
+				}
+				io_end_vec->offset = (loff_t)mpd->map.m_lblk << blkbits;
+			}
+			*map_bh = true;
+			goto out;
+		}
+		if (buffer_delay(bh)) {
+			clear_buffer_delay(bh);
+			bh->b_blocknr = pblock++;
+		}
+		clear_buffer_unwritten(bh);
+		io_end_size += (1 << blkbits);
+	} while (lblk++, (bh = bh->b_this_page) != head);
+
+	io_end_vec->size += io_end_size;
+	io_end_size = 0;
+	*map_bh = false;
+out:
+	*m_lblk = lblk;
+	*m_pblk = pblock;
+	return err;
+}
+
+/*
+ * mpage_map_buffers - update buffers corresponding to changed extent and
+ *		       submit fully mapped pages for IO
+ *
+ * @mpd - description of extent to map, on return next extent to map
+ *
+ * Scan buffers corresponding to changed extent (we expect corresponding pages
+ * to be already locked) and update buffer state according to new extent state.
+ * We map delalloc buffers to their physical location, clear unwritten bits,
+ * and mark buffers as uninit when we perform writes to unwritten extents
+ * and do extent conversion after IO is finished. If the last page is not fully
+ * mapped, we update @map to the next extent in the last page that needs
+ * mapping. Otherwise we submit the page for IO.
+ */
+static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
+{
+	struct pagevec pvec;
+	int nr_pages, i;
+	struct inode *inode = mpd->inode;
+	int bpp_bits = PAGE_SHIFT - inode->i_blkbits;
+	pgoff_t start, end;
+	ext4_lblk_t lblk;
+	ext4_fsblk_t pblock;
+	int err;
+	bool map_bh = false;
+
+	start = mpd->map.m_lblk >> bpp_bits;
+	end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
+	lblk = start << bpp_bits;
+	pblock = mpd->map.m_pblk;
+
+	pagevec_init(&pvec);
+	while (start <= end) {
+		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
+						&start, end);
+		if (nr_pages == 0)
+			break;
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			err = mpage_process_page(mpd, page, &lblk, &pblock,
+						 &map_bh);
+			/*
+			 * If map_bh is true, means page may require further bh
+			 * mapping, or maybe the page was submitted for IO.
+			 * So we return to call further extent mapping.
+			 */
+			if (err < 0 || map_bh)
+				goto out;
+			/* Page fully mapped - let IO run! */
+			err = mpage_submit_page(mpd, page);
+			if (err < 0)
+				goto out;
+		}
+		pagevec_release(&pvec);
+	}
+	/* Extent fully mapped and matches with page boundary. We are done. */
+	mpd->map.m_len = 0;
+	mpd->map.m_flags = 0;
+	return 0;
+out:
+	pagevec_release(&pvec);
+	return err;
+}
+
+static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
+{
+	struct inode *inode = mpd->inode;
+	struct ext4_map_blocks *map = &mpd->map;
+	int get_blocks_flags;
+	int err, dioread_nolock;
+
+	trace_ext4_da_write_pages_extent(inode, map);
+	/*
+	 * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
+	 * to convert an unwritten extent to be initialized (in the case
+	 * where we have written into one or more preallocated blocks).  It is
+	 * possible that we're going to need more metadata blocks than
+	 * previously reserved. However we must not fail because we're in
+	 * writeback and there is nothing we can do about it so it might result
+	 * in data loss.  So use reserved blocks to allocate metadata if
+	 * possible.
+	 *
+	 * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE if
+	 * the blocks in question are delalloc blocks.  This indicates
+	 * that the blocks and quotas has already been checked when
+	 * the data was copied into the page cache.
+	 */
+	get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
+			   EXT4_GET_BLOCKS_METADATA_NOFAIL |
+			   EXT4_GET_BLOCKS_IO_SUBMIT;
+	dioread_nolock = ext4_should_dioread_nolock(inode);
+	if (dioread_nolock)
+		get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
+	if (map->m_flags & BIT(BH_Delay))
+		get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
+
+	err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
+	if (err < 0)
+		return err;
+	if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
+		if (!mpd->io_submit.io_end->handle &&
+		    ext4_handle_valid(handle)) {
+			mpd->io_submit.io_end->handle = handle->h_rsv_handle;
+			handle->h_rsv_handle = NULL;
+		}
+		ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
+	}
+
+	BUG_ON(map->m_len == 0);
+	return 0;
+}
+
+/*
+ * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
+ *				 mpd->len and submit pages underlying it for IO
+ *
+ * @handle - handle for journal operations
+ * @mpd - extent to map
+ * @give_up_on_write - we set this to true iff there is a fatal error and there
+ *                     is no hope of writing the data. The caller should discard
+ *                     dirty pages to avoid infinite loops.
+ *
+ * The function maps extent starting at mpd->lblk of length mpd->len. If it is
+ * delayed, blocks are allocated, if it is unwritten, we may need to convert
+ * them to initialized or split the described range from larger unwritten
+ * extent. Note that we need not map all the described range since allocation
+ * can return less blocks or the range is covered by more unwritten extents. We
+ * cannot map more because we are limited by reserved transaction credits. On
+ * the other hand we always make sure that the last touched page is fully
+ * mapped so that it can be written out (and thus forward progress is
+ * guaranteed). After mapping we submit all mapped pages for IO.
+ */
+static int mpage_map_and_submit_extent(handle_t *handle,
+				       struct mpage_da_data *mpd,
+				       bool *give_up_on_write)
+{
+	struct inode *inode = mpd->inode;
+	struct ext4_map_blocks *map = &mpd->map;
+	int err;
+	loff_t disksize;
+	int progress = 0;
+	ext4_io_end_t *io_end = mpd->io_submit.io_end;
+	struct ext4_io_end_vec *io_end_vec;
+
+	io_end_vec = ext4_alloc_io_end_vec(io_end);
+	if (IS_ERR(io_end_vec))
+		return PTR_ERR(io_end_vec);
+	io_end_vec->offset = ((loff_t)map->m_lblk) << inode->i_blkbits;
+	do {
+		err = mpage_map_one_extent(handle, mpd);
+		if (err < 0) {
+			struct super_block *sb = inode->i_sb;
+
+			if (ext4_forced_shutdown(EXT4_SB(sb)) ||
+			    ext4_test_mount_flag(sb, EXT4_MF_FS_ABORTED))
+				goto invalidate_dirty_pages;
+			/*
+			 * Let the uper layers retry transient errors.
+			 * In the case of ENOSPC, if ext4_count_free_blocks()
+			 * is non-zero, a commit should free up blocks.
+			 */
+			if ((err == -ENOMEM) ||
+			    (err == -ENOSPC && ext4_count_free_clusters(sb))) {
+				if (progress)
+					goto update_disksize;
+				return err;
+			}
+			ext4_msg(sb, KERN_CRIT,
+				 "Delayed block allocation failed for "
+				 "inode %lu at logical offset %llu with"
+				 " max blocks %u with error %d",
+				 inode->i_ino,
+				 (unsigned long long)map->m_lblk,
+				 (unsigned)map->m_len, -err);
+			ext4_msg(sb, KERN_CRIT,
+				 "This should not happen!! Data will "
+				 "be lost\n");
+			if (err == -ENOSPC)
+				ext4_print_free_blocks(inode);
+		invalidate_dirty_pages:
+			*give_up_on_write = true;
+			return err;
+		}
+		progress = 1;
+		/*
+		 * Update buffer state, submit mapped pages, and get us new
+		 * extent to map
+		 */
+		err = mpage_map_and_submit_buffers(mpd);
+		if (err < 0)
+			goto update_disksize;
+	} while (map->m_len);
+
+update_disksize:
+	/*
+	 * Update on-disk size after IO is submitted.  Races with
+	 * truncate are avoided by checking i_size under i_data_sem.
+	 */
+	disksize = ((loff_t)mpd->first_page) << PAGE_SHIFT;
+	if (disksize > READ_ONCE(EXT4_I(inode)->i_disksize)) {
+		int err2;
+		loff_t i_size;
+
+		down_write(&EXT4_I(inode)->i_data_sem);
+		i_size = i_size_read(inode);
+		if (disksize > i_size)
+			disksize = i_size;
+		if (disksize > EXT4_I(inode)->i_disksize)
+			EXT4_I(inode)->i_disksize = disksize;
+		up_write(&EXT4_I(inode)->i_data_sem);
+		err2 = ext4_mark_inode_dirty(handle, inode);
+		if (err2) {
+			ext4_error_err(inode->i_sb, -err2,
+				       "Failed to mark inode %lu dirty",
+				       inode->i_ino);
+		}
+		if (!err)
+			err = err2;
+	}
+	return err;
+}
+
+/*
+ * Calculate the total number of credits to reserve for one writepages
+ * iteration. This is called from ext4_writepages(). We map an extent of
+ * up to MAX_WRITEPAGES_EXTENT_LEN blocks and then we go on and finish mapping
+ * the last partial page. So in total we can map MAX_WRITEPAGES_EXTENT_LEN +
+ * bpp - 1 blocks in bpp different extents.
+ */
+static int ext4_da_writepages_trans_blocks(struct inode *inode)
+{
+	int bpp = ext4_journal_blocks_per_page(inode);
+
+	return ext4_meta_trans_blocks(inode,
+				MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
+}
+
+/*
+ * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
+ * 				 and underlying extent to map
+ *
+ * @mpd - where to look for pages
+ *
+ * Walk dirty pages in the mapping. If they are fully mapped, submit them for
+ * IO immediately. When we find a page which isn't mapped we start accumulating
+ * extent of buffers underlying these pages that needs mapping (formed by
+ * either delayed or unwritten buffers). We also lock the pages containing
+ * these buffers. The extent found is returned in @mpd structure (starting at
+ * mpd->lblk with length mpd->len blocks).
+ *
+ * Note that this function can attach bios to one io_end structure which are
+ * neither logically nor physically contiguous. Although it may seem as an
+ * unnecessary complication, it is actually inevitable in blocksize < pagesize
+ * case as we need to track IO to all buffers underlying a page in one io_end.
+ */
+static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
+{
+	struct address_space *mapping = mpd->inode->i_mapping;
+	struct pagevec pvec;
+	unsigned int nr_pages;
+	long left = mpd->wbc->nr_to_write;
+	pgoff_t index = mpd->first_page;
+	pgoff_t end = mpd->last_page;
+	xa_mark_t tag;
+	int i, err = 0;
+	int blkbits = mpd->inode->i_blkbits;
+	ext4_lblk_t lblk;
+	struct buffer_head *head;
+
+	if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
+		tag = PAGECACHE_TAG_TOWRITE;
+	else
+		tag = PAGECACHE_TAG_DIRTY;
+
+	pagevec_init(&pvec);
+	mpd->map.m_len = 0;
+	mpd->next_page = index;
+	while (index <= end) {
+		nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
+				tag);
+		if (nr_pages == 0)
+			break;
+
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			/*
+			 * Accumulated enough dirty pages? This doesn't apply
+			 * to WB_SYNC_ALL mode. For integrity sync we have to
+			 * keep going because someone may be concurrently
+			 * dirtying pages, and we might have synced a lot of
+			 * newly appeared dirty pages, but have not synced all
+			 * of the old dirty pages.
+			 */
+			if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0)
+				goto out;
+
+			/* If we can't merge this page, we are done. */
+			if (mpd->map.m_len > 0 && mpd->next_page != page->index)
+				goto out;
+
+			lock_page(page);
+			/*
+			 * If the page is no longer dirty, or its mapping no
+			 * longer corresponds to inode we are writing (which
+			 * means it has been truncated or invalidated), or the
+			 * page is already under writeback and we are not doing
+			 * a data integrity writeback, skip the page
+			 */
+			if (!PageDirty(page) ||
+			    (PageWriteback(page) &&
+			     (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
+			    unlikely(page->mapping != mapping)) {
+				unlock_page(page);
+				continue;
+			}
+
+			wait_on_page_writeback(page);
+			BUG_ON(PageWriteback(page));
+
+			/*
+			 * Should never happen but for buggy code in
+			 * other subsystems that call
+			 * set_page_dirty() without properly warning
+			 * the file system first.  See [1] for more
+			 * information.
+			 *
+			 * [1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz
+			 */
+			if (!page_has_buffers(page)) {
+				ext4_warning_inode(mpd->inode, "page %lu does not have buffers attached", page->index);
+				ClearPageDirty(page);
+				unlock_page(page);
+				continue;
+			}
+
+			if (mpd->map.m_len == 0)
+				mpd->first_page = page->index;
+			mpd->next_page = page->index + 1;
+			/* Add all dirty buffers to mpd */
+			lblk = ((ext4_lblk_t)page->index) <<
+				(PAGE_SHIFT - blkbits);
+			head = page_buffers(page);
+			err = mpage_process_page_bufs(mpd, head, head, lblk);
+			if (err <= 0)
+				goto out;
+			err = 0;
+			left--;
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+	mpd->scanned_until_end = 1;
+	return 0;
+out:
+	pagevec_release(&pvec);
+	return err;
+}
+
+static int ext4_writepages(struct address_space *mapping,
+			   struct writeback_control *wbc)
+{
+	pgoff_t	writeback_index = 0;
+	long nr_to_write = wbc->nr_to_write;
+	int range_whole = 0;
+	int cycled = 1;
+	handle_t *handle = NULL;
+	struct mpage_da_data mpd;
+	struct inode *inode = mapping->host;
+	int needed_blocks, rsv_blocks = 0, ret = 0;
+	struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
+	struct blk_plug plug;
+	bool give_up_on_write = false;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	percpu_down_read(&sbi->s_writepages_rwsem);
+	trace_ext4_writepages(inode, wbc);
+
+	/*
+	 * No pages to write? This is mainly a kludge to avoid starting
+	 * a transaction for special inodes like journal inode on last iput()
+	 * because that could violate lock ordering on umount
+	 */
+	if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
+		goto out_writepages;
+
+	if (ext4_should_journal_data(inode)) {
+		ret = generic_writepages(mapping, wbc);
+		goto out_writepages;
+	}
+
+	/*
+	 * If the filesystem has aborted, it is read-only, so return
+	 * right away instead of dumping stack traces later on that
+	 * will obscure the real source of the problem.  We test
+	 * EXT4_MF_FS_ABORTED instead of sb->s_flag's SB_RDONLY because
+	 * the latter could be true if the filesystem is mounted
+	 * read-only, and in that case, ext4_writepages should
+	 * *never* be called, so if that ever happens, we would want
+	 * the stack trace.
+	 */
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(mapping->host->i_sb)) ||
+		     ext4_test_mount_flag(inode->i_sb, EXT4_MF_FS_ABORTED))) {
+		ret = -EROFS;
+		goto out_writepages;
+	}
+
+	/*
+	 * If we have inline data and arrive here, it means that
+	 * we will soon create the block for the 1st page, so
+	 * we'd better clear the inline data here.
+	 */
+	if (ext4_has_inline_data(inode)) {
+		/* Just inode will be modified... */
+		handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
+		if (IS_ERR(handle)) {
+			ret = PTR_ERR(handle);
+			goto out_writepages;
+		}
+		BUG_ON(ext4_test_inode_state(inode,
+				EXT4_STATE_MAY_INLINE_DATA));
+		ext4_destroy_inline_data(handle, inode);
+		ext4_journal_stop(handle);
+	}
+
+	if (ext4_should_dioread_nolock(inode)) {
+		/*
+		 * We may need to convert up to one extent per block in
+		 * the page and we may dirty the inode.
+		 */
+		rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
+						PAGE_SIZE >> inode->i_blkbits);
+	}
+
+	if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
+		range_whole = 1;
+
+	if (wbc->range_cyclic) {
+		writeback_index = mapping->writeback_index;
+		if (writeback_index)
+			cycled = 0;
+		mpd.first_page = writeback_index;
+		mpd.last_page = -1;
+	} else {
+		mpd.first_page = wbc->range_start >> PAGE_SHIFT;
+		mpd.last_page = wbc->range_end >> PAGE_SHIFT;
+	}
+
+	mpd.inode = inode;
+	mpd.wbc = wbc;
+	ext4_io_submit_init(&mpd.io_submit, wbc);
+retry:
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
+	blk_start_plug(&plug);
+
+	/*
+	 * First writeback pages that don't need mapping - we can avoid
+	 * starting a transaction unnecessarily and also avoid being blocked
+	 * in the block layer on device congestion while having transaction
+	 * started.
+	 */
+	mpd.do_map = 0;
+	mpd.scanned_until_end = 0;
+	mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
+	if (!mpd.io_submit.io_end) {
+		ret = -ENOMEM;
+		goto unplug;
+	}
+	ret = mpage_prepare_extent_to_map(&mpd);
+	/* Unlock pages we didn't use */
+	mpage_release_unused_pages(&mpd, false);
+	/* Submit prepared bio */
+	ext4_io_submit(&mpd.io_submit);
+	ext4_put_io_end_defer(mpd.io_submit.io_end);
+	mpd.io_submit.io_end = NULL;
+	if (ret < 0)
+		goto unplug;
+
+	while (!mpd.scanned_until_end && wbc->nr_to_write > 0) {
+		/* For each extent of pages we use new io_end */
+		mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
+		if (!mpd.io_submit.io_end) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		/*
+		 * We have two constraints: We find one extent to map and we
+		 * must always write out whole page (makes a difference when
+		 * blocksize < pagesize) so that we don't block on IO when we
+		 * try to write out the rest of the page. Journalled mode is
+		 * not supported by delalloc.
+		 */
+		BUG_ON(ext4_should_journal_data(inode));
+		needed_blocks = ext4_da_writepages_trans_blocks(inode);
+
+		/* start a new transaction */
+		handle = ext4_journal_start_with_reserve(inode,
+				EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
+		if (IS_ERR(handle)) {
+			ret = PTR_ERR(handle);
+			ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
+			       "%ld pages, ino %lu; err %d", __func__,
+				wbc->nr_to_write, inode->i_ino, ret);
+			/* Release allocated io_end */
+			ext4_put_io_end(mpd.io_submit.io_end);
+			mpd.io_submit.io_end = NULL;
+			break;
+		}
+		mpd.do_map = 1;
+
+		trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
+		ret = mpage_prepare_extent_to_map(&mpd);
+		if (!ret && mpd.map.m_len)
+			ret = mpage_map_and_submit_extent(handle, &mpd,
+					&give_up_on_write);
+		/*
+		 * Caution: If the handle is synchronous,
+		 * ext4_journal_stop() can wait for transaction commit
+		 * to finish which may depend on writeback of pages to
+		 * complete or on page lock to be released.  In that
+		 * case, we have to wait until after we have
+		 * submitted all the IO, released page locks we hold,
+		 * and dropped io_end reference (for extent conversion
+		 * to be able to complete) before stopping the handle.
+		 */
+		if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
+			ext4_journal_stop(handle);
+			handle = NULL;
+			mpd.do_map = 0;
+		}
+		/* Unlock pages we didn't use */
+		mpage_release_unused_pages(&mpd, give_up_on_write);
+		/* Submit prepared bio */
+		ext4_io_submit(&mpd.io_submit);
+
+		/*
+		 * Drop our io_end reference we got from init. We have
+		 * to be careful and use deferred io_end finishing if
+		 * we are still holding the transaction as we can
+		 * release the last reference to io_end which may end
+		 * up doing unwritten extent conversion.
+		 */
+		if (handle) {
+			ext4_put_io_end_defer(mpd.io_submit.io_end);
+			ext4_journal_stop(handle);
+		} else
+			ext4_put_io_end(mpd.io_submit.io_end);
+		mpd.io_submit.io_end = NULL;
+
+		if (ret == -ENOSPC && sbi->s_journal) {
+			/*
+			 * Commit the transaction which would
+			 * free blocks released in the transaction
+			 * and try again
+			 */
+			jbd2_journal_force_commit_nested(sbi->s_journal);
+			ret = 0;
+			continue;
+		}
+		/* Fatal error - ENOMEM, EIO... */
+		if (ret)
+			break;
+	}
+unplug:
+	blk_finish_plug(&plug);
+	if (!ret && !cycled && wbc->nr_to_write > 0) {
+		cycled = 1;
+		mpd.last_page = writeback_index - 1;
+		mpd.first_page = 0;
+		goto retry;
+	}
+
+	/* Update index */
+	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+		/*
+		 * Set the writeback_index so that range_cyclic
+		 * mode will write it back later
+		 */
+		mapping->writeback_index = mpd.first_page;
+
+out_writepages:
+	trace_ext4_writepages_result(inode, wbc, ret,
+				     nr_to_write - wbc->nr_to_write);
+	percpu_up_read(&sbi->s_writepages_rwsem);
+	return ret;
+}
+
+static int ext4_dax_writepages(struct address_space *mapping,
+			       struct writeback_control *wbc)
+{
+	int ret;
+	long nr_to_write = wbc->nr_to_write;
+	struct inode *inode = mapping->host;
+	struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	percpu_down_read(&sbi->s_writepages_rwsem);
+	trace_ext4_writepages(inode, wbc);
+
+	ret = dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
+	trace_ext4_writepages_result(inode, wbc, ret,
+				     nr_to_write - wbc->nr_to_write);
+	percpu_up_read(&sbi->s_writepages_rwsem);
+	return ret;
+}
+
+static int ext4_nonda_switch(struct super_block *sb)
+{
+	s64 free_clusters, dirty_clusters;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+	/*
+	 * switch to non delalloc mode if we are running low
+	 * on free block. The free block accounting via percpu
+	 * counters can get slightly wrong with percpu_counter_batch getting
+	 * accumulated on each CPU without updating global counters
+	 * Delalloc need an accurate free block accounting. So switch
+	 * to non delalloc when we are near to error range.
+	 */
+	free_clusters =
+		percpu_counter_read_positive(&sbi->s_freeclusters_counter);
+	dirty_clusters =
+		percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
+	/*
+	 * Start pushing delalloc when 1/2 of free blocks are dirty.
+	 */
+	if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
+		try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
+
+	if (2 * free_clusters < 3 * dirty_clusters ||
+	    free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
+		/*
+		 * free block count is less than 150% of dirty blocks
+		 * or free blocks is less than watermark
+		 */
+		return 1;
+	}
+	return 0;
+}
+
+/* We always reserve for an inode update; the superblock could be there too */
+static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len)
+{
+	if (likely(ext4_has_feature_large_file(inode->i_sb)))
+		return 1;
+
+	if (pos + len <= 0x7fffffffULL)
+		return 1;
+
+	/* We might need to update the superblock to set LARGE_FILE */
+	return 2;
+}
+
+static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
+			       loff_t pos, unsigned len, unsigned flags,
+			       struct page **pagep, void **fsdata)
+{
+	int ret, retries = 0;
+	struct page *page;
+	pgoff_t index;
+	struct inode *inode = mapping->host;
+	handle_t *handle;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	index = pos >> PAGE_SHIFT;
+
+	if (ext4_nonda_switch(inode->i_sb) || S_ISLNK(inode->i_mode) ||
+	    ext4_verity_in_progress(inode)) {
+		*fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
+		return ext4_write_begin(file, mapping, pos,
+					len, flags, pagep, fsdata);
+	}
+	*fsdata = (void *)0;
+	trace_ext4_da_write_begin(inode, pos, len, flags);
+
+	if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
+		ret = ext4_da_write_inline_data_begin(mapping, inode,
+						      pos, len, flags,
+						      pagep, fsdata);
+		if (ret < 0)
+			return ret;
+		if (ret == 1)
+			return 0;
+	}
+
+	/*
+	 * grab_cache_page_write_begin() can take a long time if the
+	 * system is thrashing due to memory pressure, or if the page
+	 * is being written back.  So grab it first before we start
+	 * the transaction handle.  This also allows us to allocate
+	 * the page (if needed) without using GFP_NOFS.
+	 */
+retry_grab:
+	page = grab_cache_page_write_begin(mapping, index, flags);
+	if (!page)
+		return -ENOMEM;
+	unlock_page(page);
+
+	/*
+	 * With delayed allocation, we don't log the i_disksize update
+	 * if there is delayed block allocation. But we still need
+	 * to journalling the i_disksize update if writes to the end
+	 * of file which has an already mapped buffer.
+	 */
+retry_journal:
+	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
+				ext4_da_write_credits(inode, pos, len));
+	if (IS_ERR(handle)) {
+		put_page(page);
+		return PTR_ERR(handle);
+	}
+
+	lock_page(page);
+	if (page->mapping != mapping) {
+		/* The page got truncated from under us */
+		unlock_page(page);
+		put_page(page);
+		ext4_journal_stop(handle);
+		goto retry_grab;
+	}
+	/* In case writeback began while the page was unlocked */
+	wait_for_stable_page(page);
+
+#ifdef CONFIG_FS_ENCRYPTION
+	ret = ext4_block_write_begin(page, pos, len,
+				     ext4_da_get_block_prep);
+#else
+	ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
+#endif
+	if (ret < 0) {
+		unlock_page(page);
+		ext4_journal_stop(handle);
+		/*
+		 * block_write_begin may have instantiated a few blocks
+		 * outside i_size.  Trim these off again. Don't need
+		 * i_size_read because we hold i_mutex.
+		 */
+		if (pos + len > inode->i_size)
+			ext4_truncate_failed_write(inode);
+
+		if (ret == -ENOSPC &&
+		    ext4_should_retry_alloc(inode->i_sb, &retries))
+			goto retry_journal;
+
+		put_page(page);
+		return ret;
+	}
+
+	*pagep = page;
+	return ret;
+}
+
+/*
+ * Check if we should update i_disksize
+ * when write to the end of file but not require block allocation
+ */
+static int ext4_da_should_update_i_disksize(struct page *page,
+					    unsigned long offset)
+{
+	struct buffer_head *bh;
+	struct inode *inode = page->mapping->host;
+	unsigned int idx;
+	int i;
+
+	bh = page_buffers(page);
+	idx = offset >> inode->i_blkbits;
+
+	for (i = 0; i < idx; i++)
+		bh = bh->b_this_page;
+
+	if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
+		return 0;
+	return 1;
+}
+
+static int ext4_da_write_end(struct file *file,
+			     struct address_space *mapping,
+			     loff_t pos, unsigned len, unsigned copied,
+			     struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	int ret = 0, ret2;
+	handle_t *handle = ext4_journal_current_handle();
+	loff_t new_i_size;
+	unsigned long start, end;
+	int write_mode = (int)(unsigned long)fsdata;
+
+	if (write_mode == FALL_BACK_TO_NONDELALLOC)
+		return ext4_write_end(file, mapping, pos,
+				      len, copied, page, fsdata);
+
+	trace_ext4_da_write_end(inode, pos, len, copied);
+	start = pos & (PAGE_SIZE - 1);
+	end = start + copied - 1;
+
+	/*
+	 * Since we are holding inode lock, we are sure i_disksize <=
+	 * i_size. We also know that if i_disksize < i_size, there are
+	 * delalloc writes pending in the range upto i_size. If the end of
+	 * the current write is <= i_size, there's no need to touch
+	 * i_disksize since writeback will push i_disksize upto i_size
+	 * eventually. If the end of the current write is > i_size and
+	 * inside an allocated block (ext4_da_should_update_i_disksize()
+	 * check), we need to update i_disksize here as neither
+	 * ext4_writepage() nor certain ext4_writepages() paths not
+	 * allocating blocks update i_disksize.
+	 *
+	 * Note that we defer inode dirtying to generic_write_end() /
+	 * ext4_da_write_inline_data_end().
+	 */
+	new_i_size = pos + copied;
+	if (copied && new_i_size > inode->i_size) {
+		if (ext4_has_inline_data(inode) ||
+		    ext4_da_should_update_i_disksize(page, end))
+			ext4_update_i_disksize(inode, new_i_size);
+	}
+
+	if (write_mode != CONVERT_INLINE_DATA &&
+	    ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
+	    ext4_has_inline_data(inode))
+		ret = ext4_da_write_inline_data_end(inode, pos, len, copied,
+						     page);
+	else
+		ret = generic_write_end(file, mapping, pos, len, copied,
+							page, fsdata);
+
+	copied = ret;
+	ret2 = ext4_journal_stop(handle);
+	if (unlikely(ret2 && !ret))
+		ret = ret2;
+
+	return ret ? ret : copied;
+}
+
+/*
+ * Force all delayed allocation blocks to be allocated for a given inode.
+ */
+int ext4_alloc_da_blocks(struct inode *inode)
+{
+	trace_ext4_alloc_da_blocks(inode);
+
+	if (!EXT4_I(inode)->i_reserved_data_blocks)
+		return 0;
+
+	/*
+	 * We do something simple for now.  The filemap_flush() will
+	 * also start triggering a write of the data blocks, which is
+	 * not strictly speaking necessary (and for users of
+	 * laptop_mode, not even desirable).  However, to do otherwise
+	 * would require replicating code paths in:
+	 *
+	 * ext4_writepages() ->
+	 *    write_cache_pages() ---> (via passed in callback function)
+	 *        __mpage_da_writepage() -->
+	 *           mpage_add_bh_to_extent()
+	 *           mpage_da_map_blocks()
+	 *
+	 * The problem is that write_cache_pages(), located in
+	 * mm/page-writeback.c, marks pages clean in preparation for
+	 * doing I/O, which is not desirable if we're not planning on
+	 * doing I/O at all.
+	 *
+	 * We could call write_cache_pages(), and then redirty all of
+	 * the pages by calling redirty_page_for_writepage() but that
+	 * would be ugly in the extreme.  So instead we would need to
+	 * replicate parts of the code in the above functions,
+	 * simplifying them because we wouldn't actually intend to
+	 * write out the pages, but rather only collect contiguous
+	 * logical block extents, call the multi-block allocator, and
+	 * then update the buffer heads with the block allocations.
+	 *
+	 * For now, though, we'll cheat by calling filemap_flush(),
+	 * which will map the blocks, and start the I/O, but not
+	 * actually wait for the I/O to complete.
+	 */
+	return filemap_flush(inode->i_mapping);
+}
+
+/*
+ * bmap() is special.  It gets used by applications such as lilo and by
+ * the swapper to find the on-disk block of a specific piece of data.
+ *
+ * Naturally, this is dangerous if the block concerned is still in the
+ * journal.  If somebody makes a swapfile on an ext4 data-journaling
+ * filesystem and enables swap, then they may get a nasty shock when the
+ * data getting swapped to that swapfile suddenly gets overwritten by
+ * the original zero's written out previously to the journal and
+ * awaiting writeback in the kernel's buffer cache.
+ *
+ * So, if we see any bmap calls here on a modified, data-journaled file,
+ * take extra steps to flush any blocks which might be in the cache.
+ */
+static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
+{
+	struct inode *inode = mapping->host;
+	journal_t *journal;
+	sector_t ret = 0;
+	int err;
+
+	inode_lock_shared(inode);
+	/*
+	 * We can get here for an inline file via the FIBMAP ioctl
+	 */
+	if (ext4_has_inline_data(inode))
+		goto out;
+
+	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
+			test_opt(inode->i_sb, DELALLOC)) {
+		/*
+		 * With delalloc we want to sync the file
+		 * so that we can make sure we allocate
+		 * blocks for file
+		 */
+		filemap_write_and_wait(mapping);
+	}
+
+	if (EXT4_JOURNAL(inode) &&
+	    ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
+		/*
+		 * This is a REALLY heavyweight approach, but the use of
+		 * bmap on dirty files is expected to be extremely rare:
+		 * only if we run lilo or swapon on a freshly made file
+		 * do we expect this to happen.
+		 *
+		 * (bmap requires CAP_SYS_RAWIO so this does not
+		 * represent an unprivileged user DOS attack --- we'd be
+		 * in trouble if mortal users could trigger this path at
+		 * will.)
+		 *
+		 * NB. EXT4_STATE_JDATA is not set on files other than
+		 * regular files.  If somebody wants to bmap a directory
+		 * or symlink and gets confused because the buffer
+		 * hasn't yet been flushed to disk, they deserve
+		 * everything they get.
+		 */
+
+		ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
+		journal = EXT4_JOURNAL(inode);
+		jbd2_journal_lock_updates(journal);
+		err = jbd2_journal_flush(journal);
+		jbd2_journal_unlock_updates(journal);
+
+		if (err)
+			goto out;
+	}
+
+	ret = iomap_bmap(mapping, block, &ext4_iomap_ops);
+
+out:
+	inode_unlock_shared(inode);
+	return ret;
+}
+
+static int ext4_readpage(struct file *file, struct page *page)
+{
+	int ret = -EAGAIN;
+	struct inode *inode = page->mapping->host;
+
+	trace_ext4_readpage(page);
+
+	if (ext4_has_inline_data(inode))
+		ret = ext4_readpage_inline(inode, page);
+
+	if (ret == -EAGAIN)
+		return ext4_mpage_readpages(inode, NULL, page);
+
+	return ret;
+}
+
+static void ext4_readahead(struct readahead_control *rac)
+{
+	struct inode *inode = rac->mapping->host;
+
+	/* If the file has inline data, no need to do readahead. */
+	if (ext4_has_inline_data(inode))
+		return;
+
+	ext4_mpage_readpages(inode, rac, NULL);
+}
+
+static void ext4_invalidatepage(struct page *page, unsigned int offset,
+				unsigned int length)
+{
+	trace_ext4_invalidatepage(page, offset, length);
+
+	/* No journalling happens on data buffers when this function is used */
+	WARN_ON(page_has_buffers(page) && buffer_jbd(page_buffers(page)));
+
+	block_invalidatepage(page, offset, length);
+}
+
+static int __ext4_journalled_invalidatepage(struct page *page,
+					    unsigned int offset,
+					    unsigned int length)
+{
+	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
+
+	trace_ext4_journalled_invalidatepage(page, offset, length);
+
+	/*
+	 * If it's a full truncate we just forget about the pending dirtying
+	 */
+	if (offset == 0 && length == PAGE_SIZE)
+		ClearPageChecked(page);
+
+	return jbd2_journal_invalidatepage(journal, page, offset, length);
+}
+
+/* Wrapper for aops... */
+static void ext4_journalled_invalidatepage(struct page *page,
+					   unsigned int offset,
+					   unsigned int length)
+{
+	WARN_ON(__ext4_journalled_invalidatepage(page, offset, length) < 0);
+}
+
+static int ext4_releasepage(struct page *page, gfp_t wait)
+{
+	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
+
+	trace_ext4_releasepage(page);
+
+	/* Page has dirty journalled data -> cannot release */
+	if (PageChecked(page))
+		return 0;
+	if (journal)
+		return jbd2_journal_try_to_free_buffers(journal, page);
+	else
+		return try_to_free_buffers(page);
+}
+
+static bool ext4_inode_datasync_dirty(struct inode *inode)
+{
+	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+
+	if (journal) {
+		if (jbd2_transaction_committed(journal,
+			EXT4_I(inode)->i_datasync_tid))
+			return false;
+		if (test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT))
+			return !list_empty(&EXT4_I(inode)->i_fc_list);
+		return true;
+	}
+
+	/* Any metadata buffers to write? */
+	if (!list_empty(&inode->i_mapping->private_list))
+		return true;
+	return inode->i_state & I_DIRTY_DATASYNC;
+}
+
+static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
+			   struct ext4_map_blocks *map, loff_t offset,
+			   loff_t length)
+{
+	u8 blkbits = inode->i_blkbits;
+
+	/*
+	 * Writes that span EOF might trigger an I/O size update on completion,
+	 * so consider them to be dirty for the purpose of O_DSYNC, even if
+	 * there is no other metadata changes being made or are pending.
+	 */
+	iomap->flags = 0;
+	if (ext4_inode_datasync_dirty(inode) ||
+	    offset + length > i_size_read(inode))
+		iomap->flags |= IOMAP_F_DIRTY;
+
+	if (map->m_flags & EXT4_MAP_NEW)
+		iomap->flags |= IOMAP_F_NEW;
+
+	iomap->bdev = inode->i_sb->s_bdev;
+	iomap->dax_dev = EXT4_SB(inode->i_sb)->s_daxdev;
+	iomap->offset = (u64) map->m_lblk << blkbits;
+	iomap->length = (u64) map->m_len << blkbits;
+
+	if ((map->m_flags & EXT4_MAP_MAPPED) &&
+	    !ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		iomap->flags |= IOMAP_F_MERGED;
+
+	/*
+	 * Flags passed to ext4_map_blocks() for direct I/O writes can result
+	 * in m_flags having both EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits
+	 * set. In order for any allocated unwritten extents to be converted
+	 * into written extents correctly within the ->end_io() handler, we
+	 * need to ensure that the iomap->type is set appropriately. Hence, the
+	 * reason why we need to check whether the EXT4_MAP_UNWRITTEN bit has
+	 * been set first.
+	 */
+	if (map->m_flags & EXT4_MAP_UNWRITTEN) {
+		iomap->type = IOMAP_UNWRITTEN;
+		iomap->addr = (u64) map->m_pblk << blkbits;
+	} else if (map->m_flags & EXT4_MAP_MAPPED) {
+		iomap->type = IOMAP_MAPPED;
+		iomap->addr = (u64) map->m_pblk << blkbits;
+	} else {
+		iomap->type = IOMAP_HOLE;
+		iomap->addr = IOMAP_NULL_ADDR;
+	}
+}
+
+static int ext4_iomap_alloc(struct inode *inode, struct ext4_map_blocks *map,
+			    unsigned int flags)
+{
+	handle_t *handle;
+	u8 blkbits = inode->i_blkbits;
+	int ret, dio_credits, m_flags = 0, retries = 0;
+
+	/*
+	 * Trim the mapping request to the maximum value that we can map at
+	 * once for direct I/O.
+	 */
+	if (map->m_len > DIO_MAX_BLOCKS)
+		map->m_len = DIO_MAX_BLOCKS;
+	dio_credits = ext4_chunk_trans_blocks(inode, map->m_len);
+
+retry:
+	/*
+	 * Either we allocate blocks and then don't get an unwritten extent, so
+	 * in that case we have reserved enough credits. Or, the blocks are
+	 * already allocated and unwritten. In that case, the extent conversion
+	 * fits into the credits as well.
+	 */
+	handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+	/*
+	 * DAX and direct I/O are the only two operations that are currently
+	 * supported with IOMAP_WRITE.
+	 */
+	WARN_ON(!IS_DAX(inode) && !(flags & IOMAP_DIRECT));
+	if (IS_DAX(inode))
+		m_flags = EXT4_GET_BLOCKS_CREATE_ZERO;
+	/*
+	 * We use i_size instead of i_disksize here because delalloc writeback
+	 * can complete at any point during the I/O and subsequently push the
+	 * i_disksize out to i_size. This could be beyond where direct I/O is
+	 * happening and thus expose allocated blocks to direct I/O reads.
+	 */
+	else if (((loff_t)map->m_lblk << blkbits) >= i_size_read(inode))
+		m_flags = EXT4_GET_BLOCKS_CREATE;
+	else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		m_flags = EXT4_GET_BLOCKS_IO_CREATE_EXT;
+
+	ret = ext4_map_blocks(handle, inode, map, m_flags);
+
+	/*
+	 * We cannot fill holes in indirect tree based inodes as that could
+	 * expose stale data in the case of a crash. Use the magic error code
+	 * to fallback to buffered I/O.
+	 */
+	if (!m_flags && !ret)
+		ret = -ENOTBLK;
+
+	ext4_journal_stop(handle);
+	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+		goto retry;
+
+	return ret;
+}
+
+
+static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
+		unsigned flags, struct iomap *iomap, struct iomap *srcmap)
+{
+	int ret;
+	struct ext4_map_blocks map;
+	u8 blkbits = inode->i_blkbits;
+
+	if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
+		return -EINVAL;
+
+	if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
+		return -ERANGE;
+
+	/*
+	 * Calculate the first and last logical blocks respectively.
+	 */
+	map.m_lblk = offset >> blkbits;
+	map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
+			  EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+
+	if (flags & IOMAP_WRITE) {
+		/*
+		 * We check here if the blocks are already allocated, then we
+		 * don't need to start a journal txn and we can directly return
+		 * the mapping information. This could boost performance
+		 * especially in multi-threaded overwrite requests.
+		 */
+		if (offset + length <= i_size_read(inode)) {
+			ret = ext4_map_blocks(NULL, inode, &map, 0);
+			if (ret > 0 && (map.m_flags & EXT4_MAP_MAPPED))
+				goto out;
+		}
+		ret = ext4_iomap_alloc(inode, &map, flags);
+	} else {
+		ret = ext4_map_blocks(NULL, inode, &map, 0);
+	}
+
+	if (ret < 0)
+		return ret;
+out:
+	ext4_set_iomap(inode, iomap, &map, offset, length);
+
+	return 0;
+}
+
+static int ext4_iomap_overwrite_begin(struct inode *inode, loff_t offset,
+		loff_t length, unsigned flags, struct iomap *iomap,
+		struct iomap *srcmap)
+{
+	int ret;
+
+	/*
+	 * Even for writes we don't need to allocate blocks, so just pretend
+	 * we are reading to save overhead of starting a transaction.
+	 */
+	flags &= ~IOMAP_WRITE;
+	ret = ext4_iomap_begin(inode, offset, length, flags, iomap, srcmap);
+	WARN_ON_ONCE(!ret && iomap->type != IOMAP_MAPPED);
+	return ret;
+}
+
+static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
+			  ssize_t written, unsigned flags, struct iomap *iomap)
+{
+	/*
+	 * Check to see whether an error occurred while writing out the data to
+	 * the allocated blocks. If so, return the magic error code so that we
+	 * fallback to buffered I/O and attempt to complete the remainder of
+	 * the I/O. Any blocks that may have been allocated in preparation for
+	 * the direct I/O will be reused during buffered I/O.
+	 */
+	if (flags & (IOMAP_WRITE | IOMAP_DIRECT) && written == 0)
+		return -ENOTBLK;
+
+	return 0;
+}
+
+const struct iomap_ops ext4_iomap_ops = {
+	.iomap_begin		= ext4_iomap_begin,
+	.iomap_end		= ext4_iomap_end,
+};
+
+const struct iomap_ops ext4_iomap_overwrite_ops = {
+	.iomap_begin		= ext4_iomap_overwrite_begin,
+	.iomap_end		= ext4_iomap_end,
+};
+
+static bool ext4_iomap_is_delalloc(struct inode *inode,
+				   struct ext4_map_blocks *map)
+{
+	struct extent_status es;
+	ext4_lblk_t offset = 0, end = map->m_lblk + map->m_len - 1;
+
+	ext4_es_find_extent_range(inode, &ext4_es_is_delayed,
+				  map->m_lblk, end, &es);
+
+	if (!es.es_len || es.es_lblk > end)
+		return false;
+
+	if (es.es_lblk > map->m_lblk) {
+		map->m_len = es.es_lblk - map->m_lblk;
+		return false;
+	}
+
+	offset = map->m_lblk - es.es_lblk;
+	map->m_len = es.es_len - offset;
+
+	return true;
+}
+
+static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
+				   loff_t length, unsigned int flags,
+				   struct iomap *iomap, struct iomap *srcmap)
+{
+	int ret;
+	bool delalloc = false;
+	struct ext4_map_blocks map;
+	u8 blkbits = inode->i_blkbits;
+
+	if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
+		return -EINVAL;
+
+	if (ext4_has_inline_data(inode)) {
+		ret = ext4_inline_data_iomap(inode, iomap);
+		if (ret != -EAGAIN) {
+			if (ret == 0 && offset >= iomap->length)
+				ret = -ENOENT;
+			return ret;
+		}
+	}
+
+	/*
+	 * Calculate the first and last logical block respectively.
+	 */
+	map.m_lblk = offset >> blkbits;
+	map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
+			  EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+
+	/*
+	 * Fiemap callers may call for offset beyond s_bitmap_maxbytes.
+	 * So handle it here itself instead of querying ext4_map_blocks().
+	 * Since ext4_map_blocks() will warn about it and will return
+	 * -EIO error.
+	 */
+	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
+		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+		if (offset >= sbi->s_bitmap_maxbytes) {
+			map.m_flags = 0;
+			goto set_iomap;
+		}
+	}
+
+	ret = ext4_map_blocks(NULL, inode, &map, 0);
+	if (ret < 0)
+		return ret;
+	if (ret == 0)
+		delalloc = ext4_iomap_is_delalloc(inode, &map);
+
+set_iomap:
+	ext4_set_iomap(inode, iomap, &map, offset, length);
+	if (delalloc && iomap->type == IOMAP_HOLE)
+		iomap->type = IOMAP_DELALLOC;
+
+	return 0;
+}
+
+const struct iomap_ops ext4_iomap_report_ops = {
+	.iomap_begin = ext4_iomap_begin_report,
+};
+
+/*
+ * Pages can be marked dirty completely asynchronously from ext4's journalling
+ * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
+ * much here because ->set_page_dirty is called under VFS locks.  The page is
+ * not necessarily locked.
+ *
+ * We cannot just dirty the page and leave attached buffers clean, because the
+ * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
+ * or jbddirty because all the journalling code will explode.
+ *
+ * So what we do is to mark the page "pending dirty" and next time writepage
+ * is called, propagate that into the buffers appropriately.
+ */
+static int ext4_journalled_set_page_dirty(struct page *page)
+{
+	SetPageChecked(page);
+	return __set_page_dirty_nobuffers(page);
+}
+
+static int ext4_set_page_dirty(struct page *page)
+{
+	WARN_ON_ONCE(!PageLocked(page) && !PageDirty(page));
+	WARN_ON_ONCE(!page_has_buffers(page));
+	return __set_page_dirty_buffers(page);
+}
+
+static int ext4_iomap_swap_activate(struct swap_info_struct *sis,
+				    struct file *file, sector_t *span)
+{
+	return iomap_swapfile_activate(sis, file, span,
+				       &ext4_iomap_report_ops);
+}
+
+static const struct address_space_operations ext4_aops = {
+	.readpage		= ext4_readpage,
+	.readahead		= ext4_readahead,
+	.writepage		= ext4_writepage,
+	.writepages		= ext4_writepages,
+	.write_begin		= ext4_write_begin,
+	.write_end		= ext4_write_end,
+	.set_page_dirty		= ext4_set_page_dirty,
+	.bmap			= ext4_bmap,
+	.invalidatepage		= ext4_invalidatepage,
+	.releasepage		= ext4_releasepage,
+	.direct_IO		= noop_direct_IO,
+	.migratepage		= buffer_migrate_page,
+	.is_partially_uptodate  = block_is_partially_uptodate,
+	.error_remove_page	= generic_error_remove_page,
+	.swap_activate		= ext4_iomap_swap_activate,
+};
+
+static const struct address_space_operations ext4_journalled_aops = {
+	.readpage		= ext4_readpage,
+	.readahead		= ext4_readahead,
+	.writepage		= ext4_writepage,
+	.writepages		= ext4_writepages,
+	.write_begin		= ext4_write_begin,
+	.write_end		= ext4_journalled_write_end,
+	.set_page_dirty		= ext4_journalled_set_page_dirty,
+	.bmap			= ext4_bmap,
+	.invalidatepage		= ext4_journalled_invalidatepage,
+	.releasepage		= ext4_releasepage,
+	.direct_IO		= noop_direct_IO,
+	.is_partially_uptodate  = block_is_partially_uptodate,
+	.error_remove_page	= generic_error_remove_page,
+	.swap_activate		= ext4_iomap_swap_activate,
+};
+
+static const struct address_space_operations ext4_da_aops = {
+	.readpage		= ext4_readpage,
+	.readahead		= ext4_readahead,
+	.writepage		= ext4_writepage,
+	.writepages		= ext4_writepages,
+	.write_begin		= ext4_da_write_begin,
+	.write_end		= ext4_da_write_end,
+	.set_page_dirty		= ext4_set_page_dirty,
+	.bmap			= ext4_bmap,
+	.invalidatepage		= ext4_invalidatepage,
+	.releasepage		= ext4_releasepage,
+	.direct_IO		= noop_direct_IO,
+	.migratepage		= buffer_migrate_page,
+	.is_partially_uptodate  = block_is_partially_uptodate,
+	.error_remove_page	= generic_error_remove_page,
+	.swap_activate		= ext4_iomap_swap_activate,
+};
+
+static const struct address_space_operations ext4_dax_aops = {
+	.writepages		= ext4_dax_writepages,
+	.direct_IO		= noop_direct_IO,
+	.set_page_dirty		= noop_set_page_dirty,
+	.bmap			= ext4_bmap,
+	.invalidatepage		= noop_invalidatepage,
+	.swap_activate		= ext4_iomap_swap_activate,
+};
+
+void ext4_set_aops(struct inode *inode)
+{
+	switch (ext4_inode_journal_mode(inode)) {
+	case EXT4_INODE_ORDERED_DATA_MODE:
+	case EXT4_INODE_WRITEBACK_DATA_MODE:
+		break;
+	case EXT4_INODE_JOURNAL_DATA_MODE:
+		inode->i_mapping->a_ops = &ext4_journalled_aops;
+		return;
+	default:
+		BUG();
+	}
+	if (IS_DAX(inode))
+		inode->i_mapping->a_ops = &ext4_dax_aops;
+	else if (test_opt(inode->i_sb, DELALLOC))
+		inode->i_mapping->a_ops = &ext4_da_aops;
+	else
+		inode->i_mapping->a_ops = &ext4_aops;
+}
+
+static int __ext4_block_zero_page_range(handle_t *handle,
+		struct address_space *mapping, loff_t from, loff_t length)
+{
+	ext4_fsblk_t index = from >> PAGE_SHIFT;
+	unsigned offset = from & (PAGE_SIZE-1);
+	unsigned blocksize, pos;
+	ext4_lblk_t iblock;
+	struct inode *inode = mapping->host;
+	struct buffer_head *bh;
+	struct page *page;
+	int err = 0;
+
+	page = find_or_create_page(mapping, from >> PAGE_SHIFT,
+				   mapping_gfp_constraint(mapping, ~__GFP_FS));
+	if (!page)
+		return -ENOMEM;
+
+	blocksize = inode->i_sb->s_blocksize;
+
+	iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+
+	/* Find the buffer that contains "offset" */
+	bh = page_buffers(page);
+	pos = blocksize;
+	while (offset >= pos) {
+		bh = bh->b_this_page;
+		iblock++;
+		pos += blocksize;
+	}
+	if (buffer_freed(bh)) {
+		BUFFER_TRACE(bh, "freed: skip");
+		goto unlock;
+	}
+	if (!buffer_mapped(bh)) {
+		BUFFER_TRACE(bh, "unmapped");
+		ext4_get_block(inode, iblock, bh, 0);
+		/* unmapped? It's a hole - nothing to do */
+		if (!buffer_mapped(bh)) {
+			BUFFER_TRACE(bh, "still unmapped");
+			goto unlock;
+		}
+	}
+
+	/* Ok, it's mapped. Make sure it's up-to-date */
+	if (PageUptodate(page))
+		set_buffer_uptodate(bh);
+
+	if (!buffer_uptodate(bh)) {
+		err = ext4_read_bh_lock(bh, 0, true);
+		if (err)
+			goto unlock;
+		if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
+			/* We expect the key to be set. */
+			BUG_ON(!fscrypt_has_encryption_key(inode));
+			err = fscrypt_decrypt_pagecache_blocks(page, blocksize,
+							       bh_offset(bh));
+			if (err) {
+				clear_buffer_uptodate(bh);
+				goto unlock;
+			}
+		}
+	}
+	if (ext4_should_journal_data(inode)) {
+		BUFFER_TRACE(bh, "get write access");
+		err = ext4_journal_get_write_access(handle, bh);
+		if (err)
+			goto unlock;
+	}
+	zero_user(page, offset, length);
+	BUFFER_TRACE(bh, "zeroed end of block");
+
+	if (ext4_should_journal_data(inode)) {
+		err = ext4_handle_dirty_metadata(handle, inode, bh);
+	} else {
+		err = 0;
+		mark_buffer_dirty(bh);
+		if (ext4_should_order_data(inode))
+			err = ext4_jbd2_inode_add_write(handle, inode, from,
+					length);
+	}
+
+unlock:
+	unlock_page(page);
+	put_page(page);
+	return err;
+}
+
+/*
+ * ext4_block_zero_page_range() zeros out a mapping of length 'length'
+ * starting from file offset 'from'.  The range to be zero'd must
+ * be contained with in one block.  If the specified range exceeds
+ * the end of the block it will be shortened to end of the block
+ * that corresponds to 'from'
+ */
+static int ext4_block_zero_page_range(handle_t *handle,
+		struct address_space *mapping, loff_t from, loff_t length)
+{
+	struct inode *inode = mapping->host;
+	unsigned offset = from & (PAGE_SIZE-1);
+	unsigned blocksize = inode->i_sb->s_blocksize;
+	unsigned max = blocksize - (offset & (blocksize - 1));
+
+	/*
+	 * correct length if it does not fall between
+	 * 'from' and the end of the block
+	 */
+	if (length > max || length < 0)
+		length = max;
+
+	if (IS_DAX(inode)) {
+		return iomap_zero_range(inode, from, length, NULL,
+					&ext4_iomap_ops);
+	}
+	return __ext4_block_zero_page_range(handle, mapping, from, length);
+}
+
+/*
+ * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
+ * up to the end of the block which corresponds to `from'.
+ * This required during truncate. We need to physically zero the tail end
+ * of that block so it doesn't yield old data if the file is later grown.
+ */
+static int ext4_block_truncate_page(handle_t *handle,
+		struct address_space *mapping, loff_t from)
+{
+	unsigned offset = from & (PAGE_SIZE-1);
+	unsigned length;
+	unsigned blocksize;
+	struct inode *inode = mapping->host;
+
+	/* If we are processing an encrypted inode during orphan list handling */
+	if (IS_ENCRYPTED(inode) && !fscrypt_has_encryption_key(inode))
+		return 0;
+
+	blocksize = inode->i_sb->s_blocksize;
+	length = blocksize - (offset & (blocksize - 1));
+
+	return ext4_block_zero_page_range(handle, mapping, from, length);
+}
+
+int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
+			     loff_t lstart, loff_t length)
+{
+	struct super_block *sb = inode->i_sb;
+	struct address_space *mapping = inode->i_mapping;
+	unsigned partial_start, partial_end;
+	ext4_fsblk_t start, end;
+	loff_t byte_end = (lstart + length - 1);
+	int err = 0;
+
+	partial_start = lstart & (sb->s_blocksize - 1);
+	partial_end = byte_end & (sb->s_blocksize - 1);
+
+	start = lstart >> sb->s_blocksize_bits;
+	end = byte_end >> sb->s_blocksize_bits;
+
+	/* Handle partial zero within the single block */
+	if (start == end &&
+	    (partial_start || (partial_end != sb->s_blocksize - 1))) {
+		err = ext4_block_zero_page_range(handle, mapping,
+						 lstart, length);
+		return err;
+	}
+	/* Handle partial zero out on the start of the range */
+	if (partial_start) {
+		err = ext4_block_zero_page_range(handle, mapping,
+						 lstart, sb->s_blocksize);
+		if (err)
+			return err;
+	}
+	/* Handle partial zero out on the end of the range */
+	if (partial_end != sb->s_blocksize - 1)
+		err = ext4_block_zero_page_range(handle, mapping,
+						 byte_end - partial_end,
+						 partial_end + 1);
+	return err;
+}
+
+int ext4_can_truncate(struct inode *inode)
+{
+	if (S_ISREG(inode->i_mode))
+		return 1;
+	if (S_ISDIR(inode->i_mode))
+		return 1;
+	if (S_ISLNK(inode->i_mode))
+		return !ext4_inode_is_fast_symlink(inode);
+	return 0;
+}
+
+/*
+ * We have to make sure i_disksize gets properly updated before we truncate
+ * page cache due to hole punching or zero range. Otherwise i_disksize update
+ * can get lost as it may have been postponed to submission of writeback but
+ * that will never happen after we truncate page cache.
+ */
+int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
+				      loff_t len)
+{
+	handle_t *handle;
+	int ret;
+
+	loff_t size = i_size_read(inode);
+
+	WARN_ON(!inode_is_locked(inode));
+	if (offset > size || offset + len < size)
+		return 0;
+
+	if (EXT4_I(inode)->i_disksize >= size)
+		return 0;
+
+	handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+	ext4_update_i_disksize(inode, size);
+	ret = ext4_mark_inode_dirty(handle, inode);
+	ext4_journal_stop(handle);
+
+	return ret;
+}
+
+static void ext4_wait_dax_page(struct ext4_inode_info *ei)
+{
+	up_write(&ei->i_mmap_sem);
+	schedule();
+	down_write(&ei->i_mmap_sem);
+}
+
+int ext4_break_layouts(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct page *page;
+	int error;
+
+	if (WARN_ON_ONCE(!rwsem_is_locked(&ei->i_mmap_sem)))
+		return -EINVAL;
+
+	do {
+		page = dax_layout_busy_page(inode->i_mapping);
+		if (!page)
+			return 0;
+
+		error = ___wait_var_event(&page->_refcount,
+				atomic_read(&page->_refcount) == 1,
+				TASK_INTERRUPTIBLE, 0, 0,
+				ext4_wait_dax_page(ei));
+	} while (error == 0);
+
+	return error;
+}
+
+/*
+ * ext4_punch_hole: punches a hole in a file by releasing the blocks
+ * associated with the given offset and length
+ *
+ * @inode:  File inode
+ * @offset: The offset where the hole will begin
+ * @len:    The length of the hole
+ *
+ * Returns: 0 on success or negative on failure
+ */
+
+int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	ext4_lblk_t first_block, stop_block;
+	struct address_space *mapping = inode->i_mapping;
+	loff_t first_block_offset, last_block_offset, max_length;
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	handle_t *handle;
+	unsigned int credits;
+	int ret = 0, ret2 = 0;
+
+	trace_ext4_punch_hole(inode, offset, length, 0);
+
+	/*
+	 * Write out all dirty pages to avoid race conditions
+	 * Then release them.
+	 */
+	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
+		ret = filemap_write_and_wait_range(mapping, offset,
+						   offset + length - 1);
+		if (ret)
+			return ret;
+	}
+
+	inode_lock(inode);
+
+	/* No need to punch hole beyond i_size */
+	if (offset >= inode->i_size)
+		goto out_mutex;
+
+	/*
+	 * If the hole extends beyond i_size, set the hole
+	 * to end after the page that contains i_size
+	 */
+	if (offset + length > inode->i_size) {
+		length = inode->i_size +
+		   PAGE_SIZE - (inode->i_size & (PAGE_SIZE - 1)) -
+		   offset;
+	}
+
+	/*
+	 * For punch hole the length + offset needs to be within one block
+	 * before last range. Adjust the length if it goes beyond that limit.
+	 */
+	max_length = sbi->s_bitmap_maxbytes - inode->i_sb->s_blocksize;
+	if (offset + length > max_length)
+		length = max_length - offset;
+
+	if (offset & (sb->s_blocksize - 1) ||
+	    (offset + length) & (sb->s_blocksize - 1)) {
+		/*
+		 * Attach jinode to inode for jbd2 if we do any zeroing of
+		 * partial block
+		 */
+		ret = ext4_inode_attach_jinode(inode);
+		if (ret < 0)
+			goto out_mutex;
+
+	}
+
+	/* Wait all existing dio workers, newcomers will block on i_mutex */
+	inode_dio_wait(inode);
+
+	ret = file_modified(file);
+	if (ret)
+		goto out_mutex;
+
+	/*
+	 * Prevent page faults from reinstantiating pages we have released from
+	 * page cache.
+	 */
+	down_write(&EXT4_I(inode)->i_mmap_sem);
+
+	ret = ext4_break_layouts(inode);
+	if (ret)
+		goto out_dio;
+
+	first_block_offset = round_up(offset, sb->s_blocksize);
+	last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
+
+	/* Now release the pages and zero block aligned part of pages*/
+	if (last_block_offset > first_block_offset) {
+		ret = ext4_update_disksize_before_punch(inode, offset, length);
+		if (ret)
+			goto out_dio;
+		truncate_pagecache_range(inode, first_block_offset,
+					 last_block_offset);
+	}
+
+	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		credits = ext4_writepage_trans_blocks(inode);
+	else
+		credits = ext4_blocks_for_truncate(inode);
+	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		ext4_std_error(sb, ret);
+		goto out_dio;
+	}
+
+	ret = ext4_zero_partial_blocks(handle, inode, offset,
+				       length);
+	if (ret)
+		goto out_stop;
+
+	first_block = (offset + sb->s_blocksize - 1) >>
+		EXT4_BLOCK_SIZE_BITS(sb);
+	stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
+
+	/* If there are blocks to remove, do it */
+	if (stop_block > first_block) {
+
+		down_write(&EXT4_I(inode)->i_data_sem);
+		ext4_discard_preallocations(inode, 0);
+
+		ret = ext4_es_remove_extent(inode, first_block,
+					    stop_block - first_block);
+		if (ret) {
+			up_write(&EXT4_I(inode)->i_data_sem);
+			goto out_stop;
+		}
+
+		if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+			ret = ext4_ext_remove_space(inode, first_block,
+						    stop_block - 1);
+		else
+			ret = ext4_ind_remove_space(handle, inode, first_block,
+						    stop_block);
+
+		up_write(&EXT4_I(inode)->i_data_sem);
+	}
+	ext4_fc_track_range(handle, inode, first_block, stop_block);
+	if (IS_SYNC(inode))
+		ext4_handle_sync(handle);
+
+	inode->i_mtime = inode->i_ctime = current_time(inode);
+	ret2 = ext4_mark_inode_dirty(handle, inode);
+	if (unlikely(ret2))
+		ret = ret2;
+	if (ret >= 0)
+		ext4_update_inode_fsync_trans(handle, inode, 1);
+out_stop:
+	ext4_journal_stop(handle);
+out_dio:
+	up_write(&EXT4_I(inode)->i_mmap_sem);
+out_mutex:
+	inode_unlock(inode);
+	return ret;
+}
+
+int ext4_inode_attach_jinode(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct jbd2_inode *jinode;
+
+	if (ei->jinode || !EXT4_SB(inode->i_sb)->s_journal)
+		return 0;
+
+	jinode = jbd2_alloc_inode(GFP_KERNEL);
+	spin_lock(&inode->i_lock);
+	if (!ei->jinode) {
+		if (!jinode) {
+			spin_unlock(&inode->i_lock);
+			return -ENOMEM;
+		}
+		ei->jinode = jinode;
+		jbd2_journal_init_jbd_inode(ei->jinode, inode);
+		jinode = NULL;
+	}
+	spin_unlock(&inode->i_lock);
+	if (unlikely(jinode != NULL))
+		jbd2_free_inode(jinode);
+	return 0;
+}
+
+/*
+ * ext4_truncate()
+ *
+ * We block out ext4_get_block() block instantiations across the entire
+ * transaction, and VFS/VM ensures that ext4_truncate() cannot run
+ * simultaneously on behalf of the same inode.
+ *
+ * As we work through the truncate and commit bits of it to the journal there
+ * is one core, guiding principle: the file's tree must always be consistent on
+ * disk.  We must be able to restart the truncate after a crash.
+ *
+ * The file's tree may be transiently inconsistent in memory (although it
+ * probably isn't), but whenever we close off and commit a journal transaction,
+ * the contents of (the filesystem + the journal) must be consistent and
+ * restartable.  It's pretty simple, really: bottom up, right to left (although
+ * left-to-right works OK too).
+ *
+ * Note that at recovery time, journal replay occurs *before* the restart of
+ * truncate against the orphan inode list.
+ *
+ * The committed inode has the new, desired i_size (which is the same as
+ * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
+ * that this inode's truncate did not complete and it will again call
+ * ext4_truncate() to have another go.  So there will be instantiated blocks
+ * to the right of the truncation point in a crashed ext4 filesystem.  But
+ * that's fine - as long as they are linked from the inode, the post-crash
+ * ext4_truncate() run will find them and release them.
+ */
+int ext4_truncate(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	unsigned int credits;
+	int err = 0, err2;
+	handle_t *handle;
+	struct address_space *mapping = inode->i_mapping;
+
+	/*
+	 * There is a possibility that we're either freeing the inode
+	 * or it's a completely new inode. In those cases we might not
+	 * have i_mutex locked because it's not necessary.
+	 */
+	if (!(inode->i_state & (I_NEW|I_FREEING)))
+		WARN_ON(!inode_is_locked(inode));
+	trace_ext4_truncate_enter(inode);
+
+	if (!ext4_can_truncate(inode))
+		goto out_trace;
+
+	if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
+		ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
+
+	if (ext4_has_inline_data(inode)) {
+		int has_inline = 1;
+
+		err = ext4_inline_data_truncate(inode, &has_inline);
+		if (err || has_inline)
+			goto out_trace;
+	}
+
+	/* If we zero-out tail of the page, we have to create jinode for jbd2 */
+	if (inode->i_size & (inode->i_sb->s_blocksize - 1)) {
+		err = ext4_inode_attach_jinode(inode);
+		if (err)
+			goto out_trace;
+	}
+
+	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		credits = ext4_writepage_trans_blocks(inode);
+	else
+		credits = ext4_blocks_for_truncate(inode);
+
+	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
+	if (IS_ERR(handle)) {
+		err = PTR_ERR(handle);
+		goto out_trace;
+	}
+
+	if (inode->i_size & (inode->i_sb->s_blocksize - 1))
+		ext4_block_truncate_page(handle, mapping, inode->i_size);
+
+	/*
+	 * We add the inode to the orphan list, so that if this
+	 * truncate spans multiple transactions, and we crash, we will
+	 * resume the truncate when the filesystem recovers.  It also
+	 * marks the inode dirty, to catch the new size.
+	 *
+	 * Implication: the file must always be in a sane, consistent
+	 * truncatable state while each transaction commits.
+	 */
+	err = ext4_orphan_add(handle, inode);
+	if (err)
+		goto out_stop;
+
+	down_write(&EXT4_I(inode)->i_data_sem);
+
+	ext4_discard_preallocations(inode, 0);
+
+	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		err = ext4_ext_truncate(handle, inode);
+	else
+		ext4_ind_truncate(handle, inode);
+
+	up_write(&ei->i_data_sem);
+	if (err)
+		goto out_stop;
+
+	if (IS_SYNC(inode))
+		ext4_handle_sync(handle);
+
+out_stop:
+	/*
+	 * If this was a simple ftruncate() and the file will remain alive,
+	 * then we need to clear up the orphan record which we created above.
+	 * However, if this was a real unlink then we were called by
+	 * ext4_evict_inode(), and we allow that function to clean up the
+	 * orphan info for us.
+	 */
+	if (inode->i_nlink)
+		ext4_orphan_del(handle, inode);
+
+	inode->i_mtime = inode->i_ctime = current_time(inode);
+	err2 = ext4_mark_inode_dirty(handle, inode);
+	if (unlikely(err2 && !err))
+		err = err2;
+	ext4_journal_stop(handle);
+
+out_trace:
+	trace_ext4_truncate_exit(inode);
+	return err;
+}
+
+/*
+ * ext4_get_inode_loc returns with an extra refcount against the inode's
+ * underlying buffer_head on success. If 'in_mem' is true, we have all
+ * data in memory that is needed to recreate the on-disk version of this
+ * inode.
+ */
+static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino,
+				struct ext4_iloc *iloc, int in_mem,
+				ext4_fsblk_t *ret_block)
+{
+	struct ext4_group_desc	*gdp;
+	struct buffer_head	*bh;
+	ext4_fsblk_t		block;
+	struct blk_plug		plug;
+	int			inodes_per_block, inode_offset;
+
+	iloc->bh = NULL;
+	if (ino < EXT4_ROOT_INO ||
+	    ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))
+		return -EFSCORRUPTED;
+
+	iloc->block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
+	gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
+	if (!gdp)
+		return -EIO;
+
+	/*
+	 * Figure out the offset within the block group inode table
+	 */
+	inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
+	inode_offset = ((ino - 1) %
+			EXT4_INODES_PER_GROUP(sb));
+	iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
+
+	block = ext4_inode_table(sb, gdp);
+	if ((block <= le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) ||
+	    (block >= ext4_blocks_count(EXT4_SB(sb)->s_es))) {
+		ext4_error(sb, "Invalid inode table block %llu in "
+			   "block_group %u", block, iloc->block_group);
+		return -EFSCORRUPTED;
+	}
+	block += (inode_offset / inodes_per_block);
+
+	bh = sb_getblk(sb, block);
+	if (unlikely(!bh))
+		return -ENOMEM;
+	if (ext4_simulate_fail(sb, EXT4_SIM_INODE_EIO))
+		goto simulate_eio;
+	if (!buffer_uptodate(bh)) {
+		lock_buffer(bh);
+
+		if (ext4_buffer_uptodate(bh)) {
+			/* someone brought it uptodate while we waited */
+			unlock_buffer(bh);
+			goto has_buffer;
+		}
+
+		/*
+		 * If we have all information of the inode in memory and this
+		 * is the only valid inode in the block, we need not read the
+		 * block.
+		 */
+		if (in_mem) {
+			struct buffer_head *bitmap_bh;
+			int i, start;
+
+			start = inode_offset & ~(inodes_per_block - 1);
+
+			/* Is the inode bitmap in cache? */
+			bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
+			if (unlikely(!bitmap_bh))
+				goto make_io;
+
+			/*
+			 * If the inode bitmap isn't in cache then the
+			 * optimisation may end up performing two reads instead
+			 * of one, so skip it.
+			 */
+			if (!buffer_uptodate(bitmap_bh)) {
+				brelse(bitmap_bh);
+				goto make_io;
+			}
+			for (i = start; i < start + inodes_per_block; i++) {
+				if (i == inode_offset)
+					continue;
+				if (ext4_test_bit(i, bitmap_bh->b_data))
+					break;
+			}
+			brelse(bitmap_bh);
+			if (i == start + inodes_per_block) {
+				/* all other inodes are free, so skip I/O */
+				memset(bh->b_data, 0, bh->b_size);
+				set_buffer_uptodate(bh);
+				unlock_buffer(bh);
+				goto has_buffer;
+			}
+		}
+
+make_io:
+		/*
+		 * If we need to do any I/O, try to pre-readahead extra
+		 * blocks from the inode table.
+		 */
+		blk_start_plug(&plug);
+		if (EXT4_SB(sb)->s_inode_readahead_blks) {
+			ext4_fsblk_t b, end, table;
+			unsigned num;
+			__u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;
+
+			table = ext4_inode_table(sb, gdp);
+			/* s_inode_readahead_blks is always a power of 2 */
+			b = block & ~((ext4_fsblk_t) ra_blks - 1);
+			if (table > b)
+				b = table;
+			end = b + ra_blks;
+			num = EXT4_INODES_PER_GROUP(sb);
+			if (ext4_has_group_desc_csum(sb))
+				num -= ext4_itable_unused_count(sb, gdp);
+			table += num / inodes_per_block;
+			if (end > table)
+				end = table;
+			while (b <= end)
+				ext4_sb_breadahead_unmovable(sb, b++);
+		}
+
+		/*
+		 * There are other valid inodes in the buffer, this inode
+		 * has in-inode xattrs, or we don't have this inode in memory.
+		 * Read the block from disk.
+		 */
+		trace_ext4_load_inode(sb, ino);
+		ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO, NULL);
+		blk_finish_plug(&plug);
+		wait_on_buffer(bh);
+		if (!buffer_uptodate(bh)) {
+		simulate_eio:
+			if (ret_block)
+				*ret_block = block;
+			brelse(bh);
+			return -EIO;
+		}
+	}
+has_buffer:
+	iloc->bh = bh;
+	return 0;
+}
+
+static int __ext4_get_inode_loc_noinmem(struct inode *inode,
+					struct ext4_iloc *iloc)
+{
+	ext4_fsblk_t err_blk = 0;
+	int ret;
+
+	ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, iloc, 0,
+					&err_blk);
+
+	if (ret == -EIO)
+		ext4_error_inode_block(inode, err_blk, EIO,
+					"unable to read itable block");
+
+	return ret;
+}
+
+int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
+{
+	ext4_fsblk_t err_blk = 0;
+	int ret;
+
+	/* We have all inode data except xattrs in memory here. */
+	ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, iloc,
+		!ext4_test_inode_state(inode, EXT4_STATE_XATTR), &err_blk);
+
+	if (ret == -EIO)
+		ext4_error_inode_block(inode, err_blk, EIO,
+					"unable to read itable block");
+
+	return ret;
+}
+
+
+int ext4_get_fc_inode_loc(struct super_block *sb, unsigned long ino,
+			  struct ext4_iloc *iloc)
+{
+	return __ext4_get_inode_loc(sb, ino, iloc, 0, NULL);
+}
+
+static bool ext4_should_enable_dax(struct inode *inode)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+	if (test_opt2(inode->i_sb, DAX_NEVER))
+		return false;
+	if (!S_ISREG(inode->i_mode))
+		return false;
+	if (ext4_should_journal_data(inode))
+		return false;
+	if (ext4_has_inline_data(inode))
+		return false;
+	if (ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT))
+		return false;
+	if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY))
+		return false;
+	if (!test_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags))
+		return false;
+	if (test_opt(inode->i_sb, DAX_ALWAYS))
+		return true;
+
+	return ext4_test_inode_flag(inode, EXT4_INODE_DAX);
+}
+
+void ext4_set_inode_flags(struct inode *inode, bool init)
+{
+	unsigned int flags = EXT4_I(inode)->i_flags;
+	unsigned int new_fl = 0;
+
+	WARN_ON_ONCE(IS_DAX(inode) && init);
+
+	if (flags & EXT4_SYNC_FL)
+		new_fl |= S_SYNC;
+	if (flags & EXT4_APPEND_FL)
+		new_fl |= S_APPEND;
+	if (flags & EXT4_IMMUTABLE_FL)
+		new_fl |= S_IMMUTABLE;
+	if (flags & EXT4_NOATIME_FL)
+		new_fl |= S_NOATIME;
+	if (flags & EXT4_DIRSYNC_FL)
+		new_fl |= S_DIRSYNC;
+
+	/* Because of the way inode_set_flags() works we must preserve S_DAX
+	 * here if already set. */
+	new_fl |= (inode->i_flags & S_DAX);
+	if (init && ext4_should_enable_dax(inode))
+		new_fl |= S_DAX;
+
+	if (flags & EXT4_ENCRYPT_FL)
+		new_fl |= S_ENCRYPTED;
+	if (flags & EXT4_CASEFOLD_FL)
+		new_fl |= S_CASEFOLD;
+	if (flags & EXT4_VERITY_FL)
+		new_fl |= S_VERITY;
+	inode_set_flags(inode, new_fl,
+			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX|
+			S_ENCRYPTED|S_CASEFOLD|S_VERITY);
+}
+
+static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
+				  struct ext4_inode_info *ei)
+{
+	blkcnt_t i_blocks ;
+	struct inode *inode = &(ei->vfs_inode);
+	struct super_block *sb = inode->i_sb;
+
+	if (ext4_has_feature_huge_file(sb)) {
+		/* we are using combined 48 bit field */
+		i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
+					le32_to_cpu(raw_inode->i_blocks_lo);
+		if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
+			/* i_blocks represent file system block size */
+			return i_blocks  << (inode->i_blkbits - 9);
+		} else {
+			return i_blocks;
+		}
+	} else {
+		return le32_to_cpu(raw_inode->i_blocks_lo);
+	}
+}
+
+static inline int ext4_iget_extra_inode(struct inode *inode,
+					 struct ext4_inode *raw_inode,
+					 struct ext4_inode_info *ei)
+{
+	__le32 *magic = (void *)raw_inode +
+			EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
+
+	if (EXT4_INODE_HAS_XATTR_SPACE(inode)  &&
+	    *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
+		int err;
+
+		ext4_set_inode_state(inode, EXT4_STATE_XATTR);
+		err = ext4_find_inline_data_nolock(inode);
+		if (!err && ext4_has_inline_data(inode))
+			ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
+		return err;
+	} else
+		EXT4_I(inode)->i_inline_off = 0;
+	return 0;
+}
+
+int ext4_get_projid(struct inode *inode, kprojid_t *projid)
+{
+	if (!ext4_has_feature_project(inode->i_sb))
+		return -EOPNOTSUPP;
+	*projid = EXT4_I(inode)->i_projid;
+	return 0;
+}
+
+/*
+ * ext4 has self-managed i_version for ea inodes, it stores the lower 32bit of
+ * refcount in i_version, so use raw values if inode has EXT4_EA_INODE_FL flag
+ * set.
+ */
+static inline void ext4_inode_set_iversion_queried(struct inode *inode, u64 val)
+{
+	if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
+		inode_set_iversion_raw(inode, val);
+	else
+		inode_set_iversion_queried(inode, val);
+}
+static inline u64 ext4_inode_peek_iversion(const struct inode *inode)
+{
+	if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
+		return inode_peek_iversion_raw(inode);
+	else
+		return inode_peek_iversion(inode);
+}
+
+static const char *check_igot_inode(struct inode *inode, ext4_iget_flags flags)
+
+{
+	if (flags & EXT4_IGET_EA_INODE) {
+		if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
+			return "missing EA_INODE flag";
+		if (ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
+		    EXT4_I(inode)->i_file_acl)
+			return "ea_inode with extended attributes";
+	} else {
+		if ((EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
+			return "unexpected EA_INODE flag";
+	}
+	if (is_bad_inode(inode) && !(flags & EXT4_IGET_BAD))
+		return "unexpected bad inode w/o EXT4_IGET_BAD";
+	return NULL;
+}
+
+struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
+			  ext4_iget_flags flags, const char *function,
+			  unsigned int line)
+{
+	struct ext4_iloc iloc;
+	struct ext4_inode *raw_inode;
+	struct ext4_inode_info *ei;
+	struct inode *inode;
+	const char *err_str;
+	journal_t *journal = EXT4_SB(sb)->s_journal;
+	long ret;
+	loff_t size;
+	int block;
+	uid_t i_uid;
+	gid_t i_gid;
+	projid_t i_projid;
+
+	if ((!(flags & EXT4_IGET_SPECIAL) &&
+	     (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)) ||
+	    (ino < EXT4_ROOT_INO) ||
+	    (ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))) {
+		if (flags & EXT4_IGET_HANDLE)
+			return ERR_PTR(-ESTALE);
+		__ext4_error(sb, function, line, EFSCORRUPTED, 0,
+			     "inode #%lu: comm %s: iget: illegal inode #",
+			     ino, current->comm);
+		return ERR_PTR(-EFSCORRUPTED);
+	}
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW)) {
+		if ((err_str = check_igot_inode(inode, flags)) != NULL) {
+			ext4_error_inode(inode, function, line, 0, err_str);
+			iput(inode);
+			return ERR_PTR(-EFSCORRUPTED);
+		}
+		return inode;
+	}
+
+	ei = EXT4_I(inode);
+	iloc.bh = NULL;
+
+	ret = __ext4_get_inode_loc_noinmem(inode, &iloc);
+	if (ret < 0)
+		goto bad_inode;
+	raw_inode = ext4_raw_inode(&iloc);
+
+	if ((flags & EXT4_IGET_HANDLE) &&
+	    (raw_inode->i_links_count == 0) && (raw_inode->i_mode == 0)) {
+		ret = -ESTALE;
+		goto bad_inode;
+	}
+
+	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
+		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
+		if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
+			EXT4_INODE_SIZE(inode->i_sb) ||
+		    (ei->i_extra_isize & 3)) {
+			ext4_error_inode(inode, function, line, 0,
+					 "iget: bad extra_isize %u "
+					 "(inode size %u)",
+					 ei->i_extra_isize,
+					 EXT4_INODE_SIZE(inode->i_sb));
+			ret = -EFSCORRUPTED;
+			goto bad_inode;
+		}
+	} else
+		ei->i_extra_isize = 0;
+
+	/* Precompute checksum seed for inode metadata */
+	if (ext4_has_metadata_csum(sb)) {
+		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+		__u32 csum;
+		__le32 inum = cpu_to_le32(inode->i_ino);
+		__le32 gen = raw_inode->i_generation;
+		csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
+				   sizeof(inum));
+		ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
+					      sizeof(gen));
+	}
+
+	if ((!ext4_inode_csum_verify(inode, raw_inode, ei) ||
+	    ext4_simulate_fail(sb, EXT4_SIM_INODE_CRC)) &&
+	     (!(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY))) {
+		ext4_error_inode_err(inode, function, line, 0,
+				EFSBADCRC, "iget: checksum invalid");
+		ret = -EFSBADCRC;
+		goto bad_inode;
+	}
+
+	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
+	i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
+	i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
+	if (ext4_has_feature_project(sb) &&
+	    EXT4_INODE_SIZE(sb) > EXT4_GOOD_OLD_INODE_SIZE &&
+	    EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
+		i_projid = (projid_t)le32_to_cpu(raw_inode->i_projid);
+	else
+		i_projid = EXT4_DEF_PROJID;
+
+	if (!(test_opt(inode->i_sb, NO_UID32))) {
+		i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
+		i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
+	}
+	i_uid_write(inode, i_uid);
+	i_gid_write(inode, i_gid);
+	ei->i_projid = make_kprojid(&init_user_ns, i_projid);
+	set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
+
+	ext4_clear_state_flags(ei);	/* Only relevant on 32-bit archs */
+	ei->i_inline_off = 0;
+	ei->i_dir_start_lookup = 0;
+	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
+	/* We now have enough fields to check if the inode was active or not.
+	 * This is needed because nfsd might try to access dead inodes
+	 * the test is that same one that e2fsck uses
+	 * NeilBrown 1999oct15
+	 */
+	if (inode->i_nlink == 0) {
+		if ((inode->i_mode == 0 || flags & EXT4_IGET_SPECIAL ||
+		     !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
+		    ino != EXT4_BOOT_LOADER_INO) {
+			/* this inode is deleted or unallocated */
+			if (flags & EXT4_IGET_SPECIAL) {
+				ext4_error_inode(inode, function, line, 0,
+						 "iget: special inode unallocated");
+				ret = -EFSCORRUPTED;
+			} else
+				ret = -ESTALE;
+			goto bad_inode;
+		}
+		/* The only unlinked inodes we let through here have
+		 * valid i_mode and are being read by the orphan
+		 * recovery code: that's fine, we're about to complete
+		 * the process of deleting those.
+		 * OR it is the EXT4_BOOT_LOADER_INO which is
+		 * not initialized on a new filesystem. */
+	}
+	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
+	ext4_set_inode_flags(inode, true);
+	inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
+	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
+	if (ext4_has_feature_64bit(sb))
+		ei->i_file_acl |=
+			((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
+	inode->i_size = ext4_isize(sb, raw_inode);
+	if ((size = i_size_read(inode)) < 0) {
+		ext4_error_inode(inode, function, line, 0,
+				 "iget: bad i_size value: %lld", size);
+		ret = -EFSCORRUPTED;
+		goto bad_inode;
+	}
+	/*
+	 * If dir_index is not enabled but there's dir with INDEX flag set,
+	 * we'd normally treat htree data as empty space. But with metadata
+	 * checksumming that corrupts checksums so forbid that.
+	 */
+	if (!ext4_has_feature_dir_index(sb) && ext4_has_metadata_csum(sb) &&
+	    ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) {
+		ext4_error_inode(inode, function, line, 0,
+			 "iget: Dir with htree data on filesystem without dir_index feature.");
+		ret = -EFSCORRUPTED;
+		goto bad_inode;
+	}
+	ei->i_disksize = inode->i_size;
+#ifdef CONFIG_QUOTA
+	ei->i_reserved_quota = 0;
+#endif
+	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
+	ei->i_block_group = iloc.block_group;
+	ei->i_last_alloc_group = ~0;
+	/*
+	 * NOTE! The in-memory inode i_data array is in little-endian order
+	 * even on big-endian machines: we do NOT byteswap the block numbers!
+	 */
+	for (block = 0; block < EXT4_N_BLOCKS; block++)
+		ei->i_data[block] = raw_inode->i_block[block];
+	INIT_LIST_HEAD(&ei->i_orphan);
+	ext4_fc_init_inode(&ei->vfs_inode);
+
+	/*
+	 * Set transaction id's of transactions that have to be committed
+	 * to finish f[data]sync. We set them to currently running transaction
+	 * as we cannot be sure that the inode or some of its metadata isn't
+	 * part of the transaction - the inode could have been reclaimed and
+	 * now it is reread from disk.
+	 */
+	if (journal) {
+		transaction_t *transaction;
+		tid_t tid;
+
+		read_lock(&journal->j_state_lock);
+		if (journal->j_running_transaction)
+			transaction = journal->j_running_transaction;
+		else
+			transaction = journal->j_committing_transaction;
+		if (transaction)
+			tid = transaction->t_tid;
+		else
+			tid = journal->j_commit_sequence;
+		read_unlock(&journal->j_state_lock);
+		ei->i_sync_tid = tid;
+		ei->i_datasync_tid = tid;
+	}
+
+	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
+		if (ei->i_extra_isize == 0) {
+			/* The extra space is currently unused. Use it. */
+			BUILD_BUG_ON(sizeof(struct ext4_inode) & 3);
+			ei->i_extra_isize = sizeof(struct ext4_inode) -
+					    EXT4_GOOD_OLD_INODE_SIZE;
+		} else {
+			ret = ext4_iget_extra_inode(inode, raw_inode, ei);
+			if (ret)
+				goto bad_inode;
+		}
+	}
+
+	EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
+	EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
+	EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
+	EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
+
+	if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
+		u64 ivers = le32_to_cpu(raw_inode->i_disk_version);
+
+		if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
+			if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
+				ivers |=
+		    (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
+		}
+		ext4_inode_set_iversion_queried(inode, ivers);
+	}
+
+	ret = 0;
+	if (ei->i_file_acl &&
+	    !ext4_inode_block_valid(inode, ei->i_file_acl, 1)) {
+		ext4_error_inode(inode, function, line, 0,
+				 "iget: bad extended attribute block %llu",
+				 ei->i_file_acl);
+		ret = -EFSCORRUPTED;
+		goto bad_inode;
+	} else if (!ext4_has_inline_data(inode)) {
+		/* validate the block references in the inode */
+		if (!(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY) &&
+			(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+			(S_ISLNK(inode->i_mode) &&
+			!ext4_inode_is_fast_symlink(inode)))) {
+			if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+				ret = ext4_ext_check_inode(inode);
+			else
+				ret = ext4_ind_check_inode(inode);
+		}
+	}
+	if (ret)
+		goto bad_inode;
+
+	if (S_ISREG(inode->i_mode)) {
+		inode->i_op = &ext4_file_inode_operations;
+		inode->i_fop = &ext4_file_operations;
+		ext4_set_aops(inode);
+	} else if (S_ISDIR(inode->i_mode)) {
+		inode->i_op = &ext4_dir_inode_operations;
+		inode->i_fop = &ext4_dir_operations;
+	} else if (S_ISLNK(inode->i_mode)) {
+		/* VFS does not allow setting these so must be corruption */
+		if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) {
+			ext4_error_inode(inode, function, line, 0,
+					 "iget: immutable or append flags "
+					 "not allowed on symlinks");
+			ret = -EFSCORRUPTED;
+			goto bad_inode;
+		}
+		if (IS_ENCRYPTED(inode)) {
+			inode->i_op = &ext4_encrypted_symlink_inode_operations;
+			ext4_set_aops(inode);
+		} else if (ext4_inode_is_fast_symlink(inode)) {
+			inode->i_link = (char *)ei->i_data;
+			inode->i_op = &ext4_fast_symlink_inode_operations;
+			nd_terminate_link(ei->i_data, inode->i_size,
+				sizeof(ei->i_data) - 1);
+		} else {
+			inode->i_op = &ext4_symlink_inode_operations;
+			ext4_set_aops(inode);
+		}
+		inode_nohighmem(inode);
+	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
+	      S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
+		inode->i_op = &ext4_special_inode_operations;
+		if (raw_inode->i_block[0])
+			init_special_inode(inode, inode->i_mode,
+			   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
+		else
+			init_special_inode(inode, inode->i_mode,
+			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
+	} else if (ino == EXT4_BOOT_LOADER_INO) {
+		make_bad_inode(inode);
+	} else {
+		ret = -EFSCORRUPTED;
+		ext4_error_inode(inode, function, line, 0,
+				 "iget: bogus i_mode (%o)", inode->i_mode);
+		goto bad_inode;
+	}
+	if (IS_CASEFOLDED(inode) && !ext4_has_feature_casefold(inode->i_sb))
+		ext4_error_inode(inode, function, line, 0,
+				 "casefold flag without casefold feature");
+	if ((err_str = check_igot_inode(inode, flags)) != NULL) {
+		ext4_error_inode(inode, function, line, 0, err_str);
+		ret = -EFSCORRUPTED;
+		goto bad_inode;
+	}
+
+	brelse(iloc.bh);
+	unlock_new_inode(inode);
+	return inode;
+
+bad_inode:
+	brelse(iloc.bh);
+	iget_failed(inode);
+	return ERR_PTR(ret);
+}
+
+static int ext4_inode_blocks_set(handle_t *handle,
+				struct ext4_inode *raw_inode,
+				struct ext4_inode_info *ei)
+{
+	struct inode *inode = &(ei->vfs_inode);
+	u64 i_blocks = READ_ONCE(inode->i_blocks);
+	struct super_block *sb = inode->i_sb;
+
+	if (i_blocks <= ~0U) {
+		/*
+		 * i_blocks can be represented in a 32 bit variable
+		 * as multiple of 512 bytes
+		 */
+		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
+		raw_inode->i_blocks_high = 0;
+		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
+		return 0;
+	}
+	if (!ext4_has_feature_huge_file(sb))
+		return -EFBIG;
+
+	if (i_blocks <= 0xffffffffffffULL) {
+		/*
+		 * i_blocks can be represented in a 48 bit variable
+		 * as multiple of 512 bytes
+		 */
+		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
+		raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
+		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
+	} else {
+		ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
+		/* i_block is stored in file system block size */
+		i_blocks = i_blocks >> (inode->i_blkbits - 9);
+		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
+		raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
+	}
+	return 0;
+}
+
+static void __ext4_update_other_inode_time(struct super_block *sb,
+					   unsigned long orig_ino,
+					   unsigned long ino,
+					   struct ext4_inode *raw_inode)
+{
+	struct inode *inode;
+
+	inode = find_inode_by_ino_rcu(sb, ino);
+	if (!inode)
+		return;
+
+	if ((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
+			       I_DIRTY_INODE)) ||
+	    ((inode->i_state & I_DIRTY_TIME) == 0))
+		return;
+
+	spin_lock(&inode->i_lock);
+	if (((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
+				I_DIRTY_INODE)) == 0) &&
+	    (inode->i_state & I_DIRTY_TIME)) {
+		struct ext4_inode_info	*ei = EXT4_I(inode);
+
+		inode->i_state &= ~I_DIRTY_TIME;
+		spin_unlock(&inode->i_lock);
+
+		spin_lock(&ei->i_raw_lock);
+		EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
+		EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
+		EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
+		ext4_inode_csum_set(inode, raw_inode, ei);
+		spin_unlock(&ei->i_raw_lock);
+		trace_ext4_other_inode_update_time(inode, orig_ino);
+		return;
+	}
+	spin_unlock(&inode->i_lock);
+}
+
+/*
+ * Opportunistically update the other time fields for other inodes in
+ * the same inode table block.
+ */
+static void ext4_update_other_inodes_time(struct super_block *sb,
+					  unsigned long orig_ino, char *buf)
+{
+	unsigned long ino;
+	int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
+	int inode_size = EXT4_INODE_SIZE(sb);
+
+	/*
+	 * Calculate the first inode in the inode table block.  Inode
+	 * numbers are one-based.  That is, the first inode in a block
+	 * (assuming 4k blocks and 256 byte inodes) is (n*16 + 1).
+	 */
+	ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1;
+	rcu_read_lock();
+	for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
+		if (ino == orig_ino)
+			continue;
+		__ext4_update_other_inode_time(sb, orig_ino, ino,
+					       (struct ext4_inode *)buf);
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * Post the struct inode info into an on-disk inode location in the
+ * buffer-cache.  This gobbles the caller's reference to the
+ * buffer_head in the inode location struct.
+ *
+ * The caller must have write access to iloc->bh.
+ */
+static int ext4_do_update_inode(handle_t *handle,
+				struct inode *inode,
+				struct ext4_iloc *iloc)
+{
+	struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct buffer_head *bh = iloc->bh;
+	struct super_block *sb = inode->i_sb;
+	int err = 0, block;
+	int need_datasync = 0, set_large_file = 0;
+	uid_t i_uid;
+	gid_t i_gid;
+	projid_t i_projid;
+
+	spin_lock(&ei->i_raw_lock);
+
+	/* For fields not tracked in the in-memory inode,
+	 * initialise them to zero for new inodes. */
+	if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
+		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
+
+	err = ext4_inode_blocks_set(handle, raw_inode, ei);
+	if (err) {
+		spin_unlock(&ei->i_raw_lock);
+		goto out_brelse;
+	}
+
+	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
+	i_uid = i_uid_read(inode);
+	i_gid = i_gid_read(inode);
+	i_projid = from_kprojid(&init_user_ns, ei->i_projid);
+	if (!(test_opt(inode->i_sb, NO_UID32))) {
+		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
+		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
+/*
+ * Fix up interoperability with old kernels. Otherwise, old inodes get
+ * re-used with the upper 16 bits of the uid/gid intact
+ */
+		if (ei->i_dtime && list_empty(&ei->i_orphan)) {
+			raw_inode->i_uid_high = 0;
+			raw_inode->i_gid_high = 0;
+		} else {
+			raw_inode->i_uid_high =
+				cpu_to_le16(high_16_bits(i_uid));
+			raw_inode->i_gid_high =
+				cpu_to_le16(high_16_bits(i_gid));
+		}
+	} else {
+		raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
+		raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(i_gid));
+		raw_inode->i_uid_high = 0;
+		raw_inode->i_gid_high = 0;
+	}
+	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
+
+	EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
+	EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
+	EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
+	EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
+
+	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
+	raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
+	if (likely(!test_opt2(inode->i_sb, HURD_COMPAT)))
+		raw_inode->i_file_acl_high =
+			cpu_to_le16(ei->i_file_acl >> 32);
+	raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
+	if (READ_ONCE(ei->i_disksize) != ext4_isize(inode->i_sb, raw_inode)) {
+		ext4_isize_set(raw_inode, ei->i_disksize);
+		need_datasync = 1;
+	}
+	if (ei->i_disksize > 0x7fffffffULL) {
+		if (!ext4_has_feature_large_file(sb) ||
+				EXT4_SB(sb)->s_es->s_rev_level ==
+		    cpu_to_le32(EXT4_GOOD_OLD_REV))
+			set_large_file = 1;
+	}
+	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
+	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
+		if (old_valid_dev(inode->i_rdev)) {
+			raw_inode->i_block[0] =
+				cpu_to_le32(old_encode_dev(inode->i_rdev));
+			raw_inode->i_block[1] = 0;
+		} else {
+			raw_inode->i_block[0] = 0;
+			raw_inode->i_block[1] =
+				cpu_to_le32(new_encode_dev(inode->i_rdev));
+			raw_inode->i_block[2] = 0;
+		}
+	} else if (!ext4_has_inline_data(inode)) {
+		for (block = 0; block < EXT4_N_BLOCKS; block++)
+			raw_inode->i_block[block] = ei->i_data[block];
+	}
+
+	if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
+		u64 ivers = ext4_inode_peek_iversion(inode);
+
+		raw_inode->i_disk_version = cpu_to_le32(ivers);
+		if (ei->i_extra_isize) {
+			if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
+				raw_inode->i_version_hi =
+					cpu_to_le32(ivers >> 32);
+			raw_inode->i_extra_isize =
+				cpu_to_le16(ei->i_extra_isize);
+		}
+	}
+
+	BUG_ON(!ext4_has_feature_project(inode->i_sb) &&
+	       i_projid != EXT4_DEF_PROJID);
+
+	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
+	    EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
+		raw_inode->i_projid = cpu_to_le32(i_projid);
+
+	ext4_inode_csum_set(inode, raw_inode, ei);
+	spin_unlock(&ei->i_raw_lock);
+	if (inode->i_sb->s_flags & SB_LAZYTIME)
+		ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
+					      bh->b_data);
+
+	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
+	err = ext4_handle_dirty_metadata(handle, NULL, bh);
+	if (err)
+		goto out_brelse;
+	ext4_clear_inode_state(inode, EXT4_STATE_NEW);
+	if (set_large_file) {
+		BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
+		err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
+		if (err)
+			goto out_brelse;
+		ext4_set_feature_large_file(sb);
+		ext4_handle_sync(handle);
+		err = ext4_handle_dirty_super(handle, sb);
+	}
+	ext4_update_inode_fsync_trans(handle, inode, need_datasync);
+out_brelse:
+	brelse(bh);
+	ext4_std_error(inode->i_sb, err);
+	return err;
+}
+
+/*
+ * ext4_write_inode()
+ *
+ * We are called from a few places:
+ *
+ * - Within generic_file_aio_write() -> generic_write_sync() for O_SYNC files.
+ *   Here, there will be no transaction running. We wait for any running
+ *   transaction to commit.
+ *
+ * - Within flush work (sys_sync(), kupdate and such).
+ *   We wait on commit, if told to.
+ *
+ * - Within iput_final() -> write_inode_now()
+ *   We wait on commit, if told to.
+ *
+ * In all cases it is actually safe for us to return without doing anything,
+ * because the inode has been copied into a raw inode buffer in
+ * ext4_mark_inode_dirty().  This is a correctness thing for WB_SYNC_ALL
+ * writeback.
+ *
+ * Note that we are absolutely dependent upon all inode dirtiers doing the
+ * right thing: they *must* call mark_inode_dirty() after dirtying info in
+ * which we are interested.
+ *
+ * It would be a bug for them to not do this.  The code:
+ *
+ *	mark_inode_dirty(inode)
+ *	stuff();
+ *	inode->i_size = expr;
+ *
+ * is in error because write_inode() could occur while `stuff()' is running,
+ * and the new i_size will be lost.  Plus the inode will no longer be on the
+ * superblock's dirty inode list.
+ */
+int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
+{
+	int err;
+
+	if (WARN_ON_ONCE(current->flags & PF_MEMALLOC) ||
+	    sb_rdonly(inode->i_sb))
+		return 0;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	if (EXT4_SB(inode->i_sb)->s_journal) {
+		if (ext4_journal_current_handle()) {
+			jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
+			dump_stack();
+			return -EIO;
+		}
+
+		/*
+		 * No need to force transaction in WB_SYNC_NONE mode. Also
+		 * ext4_sync_fs() will force the commit after everything is
+		 * written.
+		 */
+		if (wbc->sync_mode != WB_SYNC_ALL || wbc->for_sync)
+			return 0;
+
+		err = ext4_fc_commit(EXT4_SB(inode->i_sb)->s_journal,
+						EXT4_I(inode)->i_sync_tid);
+	} else {
+		struct ext4_iloc iloc;
+
+		err = __ext4_get_inode_loc_noinmem(inode, &iloc);
+		if (err)
+			return err;
+		/*
+		 * sync(2) will flush the whole buffer cache. No need to do
+		 * it here separately for each inode.
+		 */
+		if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
+			sync_dirty_buffer(iloc.bh);
+		if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
+			ext4_error_inode_block(inode, iloc.bh->b_blocknr, EIO,
+					       "IO error syncing inode");
+			err = -EIO;
+		}
+		brelse(iloc.bh);
+	}
+	return err;
+}
+
+/*
+ * In data=journal mode ext4_journalled_invalidatepage() may fail to invalidate
+ * buffers that are attached to a page stradding i_size and are undergoing
+ * commit. In that case we have to wait for commit to finish and try again.
+ */
+static void ext4_wait_for_tail_page_commit(struct inode *inode)
+{
+	struct page *page;
+	unsigned offset;
+	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+	tid_t commit_tid = 0;
+	int ret;
+
+	offset = inode->i_size & (PAGE_SIZE - 1);
+	/*
+	 * If the page is fully truncated, we don't need to wait for any commit
+	 * (and we even should not as __ext4_journalled_invalidatepage() may
+	 * strip all buffers from the page but keep the page dirty which can then
+	 * confuse e.g. concurrent ext4_writepage() seeing dirty page without
+	 * buffers). Also we don't need to wait for any commit if all buffers in
+	 * the page remain valid. This is most beneficial for the common case of
+	 * blocksize == PAGESIZE.
+	 */
+	if (!offset || offset > (PAGE_SIZE - i_blocksize(inode)))
+		return;
+	while (1) {
+		page = find_lock_page(inode->i_mapping,
+				      inode->i_size >> PAGE_SHIFT);
+		if (!page)
+			return;
+		ret = __ext4_journalled_invalidatepage(page, offset,
+						PAGE_SIZE - offset);
+		unlock_page(page);
+		put_page(page);
+		if (ret != -EBUSY)
+			return;
+		commit_tid = 0;
+		read_lock(&journal->j_state_lock);
+		if (journal->j_committing_transaction)
+			commit_tid = journal->j_committing_transaction->t_tid;
+		read_unlock(&journal->j_state_lock);
+		if (commit_tid)
+			jbd2_log_wait_commit(journal, commit_tid);
+	}
+}
+
+/*
+ * ext4_setattr()
+ *
+ * Called from notify_change.
+ *
+ * We want to trap VFS attempts to truncate the file as soon as
+ * possible.  In particular, we want to make sure that when the VFS
+ * shrinks i_size, we put the inode on the orphan list and modify
+ * i_disksize immediately, so that during the subsequent flushing of
+ * dirty pages and freeing of disk blocks, we can guarantee that any
+ * commit will leave the blocks being flushed in an unused state on
+ * disk.  (On recovery, the inode will get truncated and the blocks will
+ * be freed, so we have a strong guarantee that no future commit will
+ * leave these blocks visible to the user.)
+ *
+ * Another thing we have to assure is that if we are in ordered mode
+ * and inode is still attached to the committing transaction, we must
+ * we start writeout of all the dirty pages which are being truncated.
+ * This way we are sure that all the data written in the previous
+ * transaction are already on disk (truncate waits for pages under
+ * writeback).
+ *
+ * Called with inode->i_mutex down.
+ */
+int ext4_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = d_inode(dentry);
+	int error, rc = 0;
+	int orphan = 0;
+	const unsigned int ia_valid = attr->ia_valid;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return -EPERM;
+
+	if (unlikely(IS_APPEND(inode) &&
+		     (ia_valid & (ATTR_MODE | ATTR_UID |
+				  ATTR_GID | ATTR_TIMES_SET))))
+		return -EPERM;
+
+	error = setattr_prepare(dentry, attr);
+	if (error)
+		return error;
+
+	error = fscrypt_prepare_setattr(dentry, attr);
+	if (error)
+		return error;
+
+	error = fsverity_prepare_setattr(dentry, attr);
+	if (error)
+		return error;
+
+	if (is_quota_modification(inode, attr)) {
+		error = dquot_initialize(inode);
+		if (error)
+			return error;
+	}
+
+	if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, inode->i_uid)) ||
+	    (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, inode->i_gid))) {
+		handle_t *handle;
+
+		/* (user+group)*(old+new) structure, inode write (sb,
+		 * inode block, ? - but truncate inode update has it) */
+		handle = ext4_journal_start(inode, EXT4_HT_QUOTA,
+			(EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb) +
+			 EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb)) + 3);
+		if (IS_ERR(handle)) {
+			error = PTR_ERR(handle);
+			goto err_out;
+		}
+
+		/* dquot_transfer() calls back ext4_get_inode_usage() which
+		 * counts xattr inode references.
+		 */
+		down_read(&EXT4_I(inode)->xattr_sem);
+		error = dquot_transfer(inode, attr);
+		up_read(&EXT4_I(inode)->xattr_sem);
+
+		if (error) {
+			ext4_journal_stop(handle);
+			return error;
+		}
+		/* Update corresponding info in inode so that everything is in
+		 * one transaction */
+		if (attr->ia_valid & ATTR_UID)
+			inode->i_uid = attr->ia_uid;
+		if (attr->ia_valid & ATTR_GID)
+			inode->i_gid = attr->ia_gid;
+		error = ext4_mark_inode_dirty(handle, inode);
+		ext4_journal_stop(handle);
+		if (unlikely(error)) {
+			return error;
+		}
+	}
+
+	if (attr->ia_valid & ATTR_SIZE) {
+		handle_t *handle;
+		loff_t oldsize = inode->i_size;
+		loff_t old_disksize;
+		int shrink = (attr->ia_size < inode->i_size);
+
+		if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
+			struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+			if (attr->ia_size > sbi->s_bitmap_maxbytes) {
+				return -EFBIG;
+			}
+		}
+		if (!S_ISREG(inode->i_mode)) {
+			return -EINVAL;
+		}
+
+		if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
+			inode_inc_iversion(inode);
+
+		if (shrink) {
+			if (ext4_should_order_data(inode)) {
+				error = ext4_begin_ordered_truncate(inode,
+							    attr->ia_size);
+				if (error)
+					goto err_out;
+			}
+			/*
+			 * Blocks are going to be removed from the inode. Wait
+			 * for dio in flight.
+			 */
+			inode_dio_wait(inode);
+		}
+
+		down_write(&EXT4_I(inode)->i_mmap_sem);
+
+		rc = ext4_break_layouts(inode);
+		if (rc) {
+			up_write(&EXT4_I(inode)->i_mmap_sem);
+			goto err_out;
+		}
+
+		if (attr->ia_size != inode->i_size) {
+			handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
+			if (IS_ERR(handle)) {
+				error = PTR_ERR(handle);
+				goto out_mmap_sem;
+			}
+			if (ext4_handle_valid(handle) && shrink) {
+				error = ext4_orphan_add(handle, inode);
+				orphan = 1;
+			}
+			/*
+			 * Update c/mtime on truncate up, ext4_truncate() will
+			 * update c/mtime in shrink case below
+			 */
+			if (!shrink) {
+				inode->i_mtime = current_time(inode);
+				inode->i_ctime = inode->i_mtime;
+			}
+
+			if (shrink)
+				ext4_fc_track_range(handle, inode,
+					(attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
+					inode->i_sb->s_blocksize_bits,
+					EXT_MAX_BLOCKS - 1);
+			else
+				ext4_fc_track_range(
+					handle, inode,
+					(oldsize > 0 ? oldsize - 1 : oldsize) >>
+					inode->i_sb->s_blocksize_bits,
+					(attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
+					inode->i_sb->s_blocksize_bits);
+
+			down_write(&EXT4_I(inode)->i_data_sem);
+			old_disksize = EXT4_I(inode)->i_disksize;
+			EXT4_I(inode)->i_disksize = attr->ia_size;
+			rc = ext4_mark_inode_dirty(handle, inode);
+			if (!error)
+				error = rc;
+			/*
+			 * We have to update i_size under i_data_sem together
+			 * with i_disksize to avoid races with writeback code
+			 * running ext4_wb_update_i_disksize().
+			 */
+			if (!error)
+				i_size_write(inode, attr->ia_size);
+			else
+				EXT4_I(inode)->i_disksize = old_disksize;
+			up_write(&EXT4_I(inode)->i_data_sem);
+			ext4_journal_stop(handle);
+			if (error)
+				goto out_mmap_sem;
+			if (!shrink) {
+				pagecache_isize_extended(inode, oldsize,
+							 inode->i_size);
+			} else if (ext4_should_journal_data(inode)) {
+				ext4_wait_for_tail_page_commit(inode);
+			}
+		}
+
+		/*
+		 * Truncate pagecache after we've waited for commit
+		 * in data=journal mode to make pages freeable.
+		 */
+		truncate_pagecache(inode, inode->i_size);
+		/*
+		 * Call ext4_truncate() even if i_size didn't change to
+		 * truncate possible preallocated blocks.
+		 */
+		if (attr->ia_size <= oldsize) {
+			rc = ext4_truncate(inode);
+			if (rc)
+				error = rc;
+		}
+out_mmap_sem:
+		up_write(&EXT4_I(inode)->i_mmap_sem);
+	}
+
+	if (!error) {
+		setattr_copy(inode, attr);
+		mark_inode_dirty(inode);
+	}
+
+	/*
+	 * If the call to ext4_truncate failed to get a transaction handle at
+	 * all, we need to clean up the in-core orphan list manually.
+	 */
+	if (orphan && inode->i_nlink)
+		ext4_orphan_del(NULL, inode);
+
+	if (!error && (ia_valid & ATTR_MODE))
+		rc = posix_acl_chmod(inode, inode->i_mode);
+
+err_out:
+	if  (error)
+		ext4_std_error(inode->i_sb, error);
+	if (!error)
+		error = rc;
+	return error;
+}
+
+int ext4_getattr(const struct path *path, struct kstat *stat,
+		 u32 request_mask, unsigned int query_flags)
+{
+	struct inode *inode = d_inode(path->dentry);
+	struct ext4_inode *raw_inode;
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	unsigned int flags;
+
+	if ((request_mask & STATX_BTIME) &&
+	    EXT4_FITS_IN_INODE(raw_inode, ei, i_crtime)) {
+		stat->result_mask |= STATX_BTIME;
+		stat->btime.tv_sec = ei->i_crtime.tv_sec;
+		stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
+	}
+
+	flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
+	if (flags & EXT4_APPEND_FL)
+		stat->attributes |= STATX_ATTR_APPEND;
+	if (flags & EXT4_COMPR_FL)
+		stat->attributes |= STATX_ATTR_COMPRESSED;
+	if (flags & EXT4_ENCRYPT_FL)
+		stat->attributes |= STATX_ATTR_ENCRYPTED;
+	if (flags & EXT4_IMMUTABLE_FL)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	if (flags & EXT4_NODUMP_FL)
+		stat->attributes |= STATX_ATTR_NODUMP;
+	if (flags & EXT4_VERITY_FL)
+		stat->attributes |= STATX_ATTR_VERITY;
+
+	stat->attributes_mask |= (STATX_ATTR_APPEND |
+				  STATX_ATTR_COMPRESSED |
+				  STATX_ATTR_ENCRYPTED |
+				  STATX_ATTR_IMMUTABLE |
+				  STATX_ATTR_NODUMP |
+				  STATX_ATTR_VERITY);
+
+	generic_fillattr(inode, stat);
+	return 0;
+}
+
+int ext4_file_getattr(const struct path *path, struct kstat *stat,
+		      u32 request_mask, unsigned int query_flags)
+{
+	struct inode *inode = d_inode(path->dentry);
+	u64 delalloc_blocks;
+
+	ext4_getattr(path, stat, request_mask, query_flags);
+
+	/*
+	 * If there is inline data in the inode, the inode will normally not
+	 * have data blocks allocated (it may have an external xattr block).
+	 * Report at least one sector for such files, so tools like tar, rsync,
+	 * others don't incorrectly think the file is completely sparse.
+	 */
+	if (unlikely(ext4_has_inline_data(inode)))
+		stat->blocks += (stat->size + 511) >> 9;
+
+	/*
+	 * We can't update i_blocks if the block allocation is delayed
+	 * otherwise in the case of system crash before the real block
+	 * allocation is done, we will have i_blocks inconsistent with
+	 * on-disk file blocks.
+	 * We always keep i_blocks updated together with real
+	 * allocation. But to not confuse with user, stat
+	 * will return the blocks that include the delayed allocation
+	 * blocks for this file.
+	 */
+	delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
+				   EXT4_I(inode)->i_reserved_data_blocks);
+	stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits - 9);
+	return 0;
+}
+
+static int ext4_index_trans_blocks(struct inode *inode, int lblocks,
+				   int pextents)
+{
+	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
+		return ext4_ind_trans_blocks(inode, lblocks);
+	return ext4_ext_index_trans_blocks(inode, pextents);
+}
+
+/*
+ * Account for index blocks, block groups bitmaps and block group
+ * descriptor blocks if modify datablocks and index blocks
+ * worse case, the indexs blocks spread over different block groups
+ *
+ * If datablocks are discontiguous, they are possible to spread over
+ * different block groups too. If they are contiguous, with flexbg,
+ * they could still across block group boundary.
+ *
+ * Also account for superblock, inode, quota and xattr blocks
+ */
+static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
+				  int pextents)
+{
+	ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
+	int gdpblocks;
+	int idxblocks;
+	int ret = 0;
+
+	/*
+	 * How many index blocks need to touch to map @lblocks logical blocks
+	 * to @pextents physical extents?
+	 */
+	idxblocks = ext4_index_trans_blocks(inode, lblocks, pextents);
+
+	ret = idxblocks;
+
+	/*
+	 * Now let's see how many group bitmaps and group descriptors need
+	 * to account
+	 */
+	groups = idxblocks + pextents;
+	gdpblocks = groups;
+	if (groups > ngroups)
+		groups = ngroups;
+	if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
+		gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
+
+	/* bitmaps and block group descriptor blocks */
+	ret += groups + gdpblocks;
+
+	/* Blocks for super block, inode, quota and xattr blocks */
+	ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
+
+	return ret;
+}
+
+/*
+ * Calculate the total number of credits to reserve to fit
+ * the modification of a single pages into a single transaction,
+ * which may include multiple chunks of block allocations.
+ *
+ * This could be called via ext4_write_begin()
+ *
+ * We need to consider the worse case, when
+ * one new block per extent.
+ */
+int ext4_writepage_trans_blocks(struct inode *inode)
+{
+	int bpp = ext4_journal_blocks_per_page(inode);
+	int ret;
+
+	ret = ext4_meta_trans_blocks(inode, bpp, bpp);
+
+	/* Account for data blocks for journalled mode */
+	if (ext4_should_journal_data(inode))
+		ret += bpp;
+	return ret;
+}
+
+/*
+ * Calculate the journal credits for a chunk of data modification.
+ *
+ * This is called from DIO, fallocate or whoever calling
+ * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
+ *
+ * journal buffers for data blocks are not included here, as DIO
+ * and fallocate do no need to journal data buffers.
+ */
+int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
+{
+	return ext4_meta_trans_blocks(inode, nrblocks, 1);
+}
+
+/*
+ * The caller must have previously called ext4_reserve_inode_write().
+ * Give this, we know that the caller already has write access to iloc->bh.
+ */
+int ext4_mark_iloc_dirty(handle_t *handle,
+			 struct inode *inode, struct ext4_iloc *iloc)
+{
+	int err = 0;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
+		put_bh(iloc->bh);
+		return -EIO;
+	}
+	ext4_fc_track_inode(handle, inode);
+
+	/*
+	 * ea_inodes are using i_version for storing reference count, don't
+	 * mess with it
+	 */
+	if (IS_I_VERSION(inode) &&
+	    !(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
+		inode_inc_iversion(inode);
+
+	/* the do_update_inode consumes one bh->b_count */
+	get_bh(iloc->bh);
+
+	/* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
+	err = ext4_do_update_inode(handle, inode, iloc);
+	put_bh(iloc->bh);
+	return err;
+}
+
+/*
+ * On success, We end up with an outstanding reference count against
+ * iloc->bh.  This _must_ be cleaned up later.
+ */
+
+int
+ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
+			 struct ext4_iloc *iloc)
+{
+	int err;
+
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	err = ext4_get_inode_loc(inode, iloc);
+	if (!err) {
+		BUFFER_TRACE(iloc->bh, "get_write_access");
+		err = ext4_journal_get_write_access(handle, iloc->bh);
+		if (err) {
+			brelse(iloc->bh);
+			iloc->bh = NULL;
+		}
+	}
+	ext4_std_error(inode->i_sb, err);
+	return err;
+}
+
+static int __ext4_expand_extra_isize(struct inode *inode,
+				     unsigned int new_extra_isize,
+				     struct ext4_iloc *iloc,
+				     handle_t *handle, int *no_expand)
+{
+	struct ext4_inode *raw_inode;
+	struct ext4_xattr_ibody_header *header;
+	unsigned int inode_size = EXT4_INODE_SIZE(inode->i_sb);
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	int error;
+
+	/* this was checked at iget time, but double check for good measure */
+	if ((EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > inode_size) ||
+	    (ei->i_extra_isize & 3)) {
+		EXT4_ERROR_INODE(inode, "bad extra_isize %u (inode size %u)",
+				 ei->i_extra_isize,
+				 EXT4_INODE_SIZE(inode->i_sb));
+		return -EFSCORRUPTED;
+	}
+	if ((new_extra_isize < ei->i_extra_isize) ||
+	    (new_extra_isize < 4) ||
+	    (new_extra_isize > inode_size - EXT4_GOOD_OLD_INODE_SIZE))
+		return -EINVAL;	/* Should never happen */
+
+	raw_inode = ext4_raw_inode(iloc);
+
+	header = IHDR(inode, raw_inode);
+
+	/* No extended attributes present */
+	if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
+	    header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
+		memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +
+		       EXT4_I(inode)->i_extra_isize, 0,
+		       new_extra_isize - EXT4_I(inode)->i_extra_isize);
+		EXT4_I(inode)->i_extra_isize = new_extra_isize;
+		return 0;
+	}
+
+	/*
+	 * We may need to allocate external xattr block so we need quotas
+	 * initialized. Here we can be called with various locks held so we
+	 * cannot affort to initialize quotas ourselves. So just bail.
+	 */
+	if (dquot_initialize_needed(inode))
+		return -EAGAIN;
+
+	/* try to expand with EAs present */
+	error = ext4_expand_extra_isize_ea(inode, new_extra_isize,
+					   raw_inode, handle);
+	if (error) {
+		/*
+		 * Inode size expansion failed; don't try again
+		 */
+		*no_expand = 1;
+	}
+
+	return error;
+}
+
+/*
+ * Expand an inode by new_extra_isize bytes.
+ * Returns 0 on success or negative error number on failure.
+ */
+static int ext4_try_to_expand_extra_isize(struct inode *inode,
+					  unsigned int new_extra_isize,
+					  struct ext4_iloc iloc,
+					  handle_t *handle)
+{
+	int no_expand;
+	int error;
+
+	if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND))
+		return -EOVERFLOW;
+
+	/*
+	 * In nojournal mode, we can immediately attempt to expand
+	 * the inode.  When journaled, we first need to obtain extra
+	 * buffer credits since we may write into the EA block
+	 * with this same handle. If journal_extend fails, then it will
+	 * only result in a minor loss of functionality for that inode.
+	 * If this is felt to be critical, then e2fsck should be run to
+	 * force a large enough s_min_extra_isize.
+	 */
+	if (ext4_journal_extend(handle,
+				EXT4_DATA_TRANS_BLOCKS(inode->i_sb), 0) != 0)
+		return -ENOSPC;
+
+	if (ext4_write_trylock_xattr(inode, &no_expand) == 0)
+		return -EBUSY;
+
+	error = __ext4_expand_extra_isize(inode, new_extra_isize, &iloc,
+					  handle, &no_expand);
+	ext4_write_unlock_xattr(inode, &no_expand);
+
+	return error;
+}
+
+int ext4_expand_extra_isize(struct inode *inode,
+			    unsigned int new_extra_isize,
+			    struct ext4_iloc *iloc)
+{
+	handle_t *handle;
+	int no_expand;
+	int error, rc;
+
+	if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
+		brelse(iloc->bh);
+		return -EOVERFLOW;
+	}
+
+	handle = ext4_journal_start(inode, EXT4_HT_INODE,
+				    EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
+	if (IS_ERR(handle)) {
+		error = PTR_ERR(handle);
+		brelse(iloc->bh);
+		return error;
+	}
+
+	ext4_write_lock_xattr(inode, &no_expand);
+
+	BUFFER_TRACE(iloc->bh, "get_write_access");
+	error = ext4_journal_get_write_access(handle, iloc->bh);
+	if (error) {
+		brelse(iloc->bh);
+		goto out_unlock;
+	}
+
+	error = __ext4_expand_extra_isize(inode, new_extra_isize, iloc,
+					  handle, &no_expand);
+
+	rc = ext4_mark_iloc_dirty(handle, inode, iloc);
+	if (!error)
+		error = rc;
+
+out_unlock:
+	ext4_write_unlock_xattr(inode, &no_expand);
+	ext4_journal_stop(handle);
+	return error;
+}
+
+/*
+ * What we do here is to mark the in-core inode as clean with respect to inode
+ * dirtiness (it may still be data-dirty).
+ * This means that the in-core inode may be reaped by prune_icache
+ * without having to perform any I/O.  This is a very good thing,
+ * because *any* task may call prune_icache - even ones which
+ * have a transaction open against a different journal.
+ *
+ * Is this cheating?  Not really.  Sure, we haven't written the
+ * inode out, but prune_icache isn't a user-visible syncing function.
+ * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
+ * we start and wait on commits.
+ */
+int __ext4_mark_inode_dirty(handle_t *handle, struct inode *inode,
+				const char *func, unsigned int line)
+{
+	struct ext4_iloc iloc;
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	int err;
+
+	might_sleep();
+	trace_ext4_mark_inode_dirty(inode, _RET_IP_);
+	err = ext4_reserve_inode_write(handle, inode, &iloc);
+	if (err)
+		goto out;
+
+	if (EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize)
+		ext4_try_to_expand_extra_isize(inode, sbi->s_want_extra_isize,
+					       iloc, handle);
+
+	err = ext4_mark_iloc_dirty(handle, inode, &iloc);
+out:
+	if (unlikely(err))
+		ext4_error_inode_err(inode, func, line, 0, err,
+					"mark_inode_dirty error");
+	return err;
+}
+
+/*
+ * ext4_dirty_inode() is called from __mark_inode_dirty()
+ *
+ * We're really interested in the case where a file is being extended.
+ * i_size has been changed by generic_commit_write() and we thus need
+ * to include the updated inode in the current transaction.
+ *
+ * Also, dquot_alloc_block() will always dirty the inode when blocks
+ * are allocated to the file.
+ *
+ * If the inode is marked synchronous, we don't honour that here - doing
+ * so would cause a commit on atime updates, which we don't bother doing.
+ * We handle synchronous inodes at the highest possible level.
+ *
+ * If only the I_DIRTY_TIME flag is set, we can skip everything.  If
+ * I_DIRTY_TIME and I_DIRTY_SYNC is set, the only inode fields we need
+ * to copy into the on-disk inode structure are the timestamp files.
+ */
+void ext4_dirty_inode(struct inode *inode, int flags)
+{
+	handle_t *handle;
+
+	if (flags == I_DIRTY_TIME)
+		return;
+	handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+	if (IS_ERR(handle))
+		goto out;
+
+	ext4_mark_inode_dirty(handle, inode);
+
+	ext4_journal_stop(handle);
+out:
+	return;
+}
+
+int ext4_change_inode_journal_flag(struct inode *inode, int val)
+{
+	journal_t *journal;
+	handle_t *handle;
+	int err;
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+	/*
+	 * We have to be very careful here: changing a data block's
+	 * journaling status dynamically is dangerous.  If we write a
+	 * data block to the journal, change the status and then delete
+	 * that block, we risk forgetting to revoke the old log record
+	 * from the journal and so a subsequent replay can corrupt data.
+	 * So, first we make sure that the journal is empty and that
+	 * nobody is changing anything.
+	 */
+
+	journal = EXT4_JOURNAL(inode);
+	if (!journal)
+		return 0;
+	if (is_journal_aborted(journal))
+		return -EROFS;
+
+	/* Wait for all existing dio workers */
+	inode_dio_wait(inode);
+
+	/*
+	 * Before flushing the journal and switching inode's aops, we have
+	 * to flush all dirty data the inode has. There can be outstanding
+	 * delayed allocations, there can be unwritten extents created by
+	 * fallocate or buffered writes in dioread_nolock mode covered by
+	 * dirty data which can be converted only after flushing the dirty
+	 * data (and journalled aops don't know how to handle these cases).
+	 */
+	if (val) {
+		down_write(&EXT4_I(inode)->i_mmap_sem);
+		err = filemap_write_and_wait(inode->i_mapping);
+		if (err < 0) {
+			up_write(&EXT4_I(inode)->i_mmap_sem);
+			return err;
+		}
+	}
+
+	percpu_down_write(&sbi->s_writepages_rwsem);
+	jbd2_journal_lock_updates(journal);
+
+	/*
+	 * OK, there are no updates running now, and all cached data is
+	 * synced to disk.  We are now in a completely consistent state
+	 * which doesn't have anything in the journal, and we know that
+	 * no filesystem updates are running, so it is safe to modify
+	 * the inode's in-core data-journaling state flag now.
+	 */
+
+	if (val)
+		ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
+	else {
+		err = jbd2_journal_flush(journal);
+		if (err < 0) {
+			jbd2_journal_unlock_updates(journal);
+			percpu_up_write(&sbi->s_writepages_rwsem);
+			return err;
+		}
+		ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
+	}
+	ext4_set_aops(inode);
+
+	jbd2_journal_unlock_updates(journal);
+	percpu_up_write(&sbi->s_writepages_rwsem);
+
+	if (val)
+		up_write(&EXT4_I(inode)->i_mmap_sem);
+
+	/* Finally we can mark the inode as dirty. */
+
+	handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+	ext4_fc_mark_ineligible(inode->i_sb,
+		EXT4_FC_REASON_JOURNAL_FLAG_CHANGE);
+	err = ext4_mark_inode_dirty(handle, inode);
+	ext4_handle_sync(handle);
+	ext4_journal_stop(handle);
+	ext4_std_error(inode->i_sb, err);
+
+	return err;
+}
+
+static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
+{
+	return !buffer_mapped(bh);
+}
+
+vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+	struct page *page = vmf->page;
+	loff_t size;
+	unsigned long len;
+	int err;
+	vm_fault_t ret;
+	struct file *file = vma->vm_file;
+	struct inode *inode = file_inode(file);
+	struct address_space *mapping = inode->i_mapping;
+	handle_t *handle;
+	get_block_t *get_block;
+	int retries = 0;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return VM_FAULT_SIGBUS;
+
+	sb_start_pagefault(inode->i_sb);
+	file_update_time(vma->vm_file);
+
+	down_read(&EXT4_I(inode)->i_mmap_sem);
+
+	err = ext4_convert_inline_data(inode);
+	if (err)
+		goto out_ret;
+
+	/*
+	 * On data journalling we skip straight to the transaction handle:
+	 * there's no delalloc; page truncated will be checked later; the
+	 * early return w/ all buffers mapped (calculates size/len) can't
+	 * be used; and there's no dioread_nolock, so only ext4_get_block.
+	 */
+	if (ext4_should_journal_data(inode))
+		goto retry_alloc;
+
+	/* Delalloc case is easy... */
+	if (test_opt(inode->i_sb, DELALLOC) &&
+	    !ext4_nonda_switch(inode->i_sb)) {
+		do {
+			err = block_page_mkwrite(vma, vmf,
+						   ext4_da_get_block_prep);
+		} while (err == -ENOSPC &&
+		       ext4_should_retry_alloc(inode->i_sb, &retries));
+		goto out_ret;
+	}
+
+	lock_page(page);
+	size = i_size_read(inode);
+	/* Page got truncated from under us? */
+	if (page->mapping != mapping || page_offset(page) > size) {
+		unlock_page(page);
+		ret = VM_FAULT_NOPAGE;
+		goto out;
+	}
+
+	if (page->index == size >> PAGE_SHIFT)
+		len = size & ~PAGE_MASK;
+	else
+		len = PAGE_SIZE;
+	/*
+	 * Return if we have all the buffers mapped. This avoids the need to do
+	 * journal_start/journal_stop which can block and take a long time
+	 *
+	 * This cannot be done for data journalling, as we have to add the
+	 * inode to the transaction's list to writeprotect pages on commit.
+	 */
+	if (page_has_buffers(page)) {
+		if (!ext4_walk_page_buffers(NULL, page_buffers(page),
+					    0, len, NULL,
+					    ext4_bh_unmapped)) {
+			/* Wait so that we don't change page under IO */
+			wait_for_stable_page(page);
+			ret = VM_FAULT_LOCKED;
+			goto out;
+		}
+	}
+	unlock_page(page);
+	/* OK, we need to fill the hole... */
+	if (ext4_should_dioread_nolock(inode))
+		get_block = ext4_get_block_unwritten;
+	else
+		get_block = ext4_get_block;
+retry_alloc:
+	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
+				    ext4_writepage_trans_blocks(inode));
+	if (IS_ERR(handle)) {
+		ret = VM_FAULT_SIGBUS;
+		goto out;
+	}
+	/*
+	 * Data journalling can't use block_page_mkwrite() because it
+	 * will set_buffer_dirty() before do_journal_get_write_access()
+	 * thus might hit warning messages for dirty metadata buffers.
+	 */
+	if (!ext4_should_journal_data(inode)) {
+		err = block_page_mkwrite(vma, vmf, get_block);
+	} else {
+		lock_page(page);
+		size = i_size_read(inode);
+		/* Page got truncated from under us? */
+		if (page->mapping != mapping || page_offset(page) > size) {
+			ret = VM_FAULT_NOPAGE;
+			goto out_error;
+		}
+
+		if (page->index == size >> PAGE_SHIFT)
+			len = size & ~PAGE_MASK;
+		else
+			len = PAGE_SIZE;
+
+		err = __block_write_begin(page, 0, len, ext4_get_block);
+		if (!err) {
+			ret = VM_FAULT_SIGBUS;
+			if (ext4_walk_page_buffers(handle, page_buffers(page),
+					0, len, NULL, do_journal_get_write_access))
+				goto out_error;
+			if (ext4_walk_page_buffers(handle, page_buffers(page),
+					0, len, NULL, write_end_fn))
+				goto out_error;
+			if (ext4_jbd2_inode_add_write(handle, inode,
+						      page_offset(page), len))
+				goto out_error;
+			ext4_set_inode_state(inode, EXT4_STATE_JDATA);
+		} else {
+			unlock_page(page);
+		}
+	}
+	ext4_journal_stop(handle);
+	if (err == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+		goto retry_alloc;
+out_ret:
+	ret = block_page_mkwrite_return(err);
+out:
+	up_read(&EXT4_I(inode)->i_mmap_sem);
+	sb_end_pagefault(inode->i_sb);
+	return ret;
+out_error:
+	unlock_page(page);
+	ext4_journal_stop(handle);
+	goto out;
+}
+
+vm_fault_t ext4_filemap_fault(struct vm_fault *vmf)
+{
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	vm_fault_t ret;
+
+	down_read(&EXT4_I(inode)->i_mmap_sem);
+	ret = filemap_fault(vmf);
+	up_read(&EXT4_I(inode)->i_mmap_sem);
+
+	return ret;
+}