1 files changed, 559 insertions, 0 deletions

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
new file mode 100644
index 000000000..d0302b66c
--- /dev/null
+++ b/fs/ext4/page-io.c
@@ -0,0 +1,559 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/ext4/page-io.c
+ *
+ * This contains the new page_io functions for ext4
+ *
+ * Written by Theodore Ts'o, 2010.
+ */
+
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/highuid.h>
+#include <linux/pagemap.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/slab.h>
+#include <linux/mm.h>
+#include <linux/sched/mm.h>
+
+#include "ext4_jbd2.h"
+#include "xattr.h"
+#include "acl.h"
+
+static struct kmem_cache *io_end_cachep;
+static struct kmem_cache *io_end_vec_cachep;
+
+int __init ext4_init_pageio(void)
+{
+	io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
+	if (io_end_cachep == NULL)
+		return -ENOMEM;
+
+	io_end_vec_cachep = KMEM_CACHE(ext4_io_end_vec, 0);
+	if (io_end_vec_cachep == NULL) {
+		kmem_cache_destroy(io_end_cachep);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void ext4_exit_pageio(void)
+{
+	kmem_cache_destroy(io_end_cachep);
+	kmem_cache_destroy(io_end_vec_cachep);
+}
+
+struct ext4_io_end_vec *ext4_alloc_io_end_vec(ext4_io_end_t *io_end)
+{
+	struct ext4_io_end_vec *io_end_vec;
+
+	io_end_vec = kmem_cache_zalloc(io_end_vec_cachep, GFP_NOFS);
+	if (!io_end_vec)
+		return ERR_PTR(-ENOMEM);
+	INIT_LIST_HEAD(&io_end_vec->list);
+	list_add_tail(&io_end_vec->list, &io_end->list_vec);
+	return io_end_vec;
+}
+
+static void ext4_free_io_end_vec(ext4_io_end_t *io_end)
+{
+	struct ext4_io_end_vec *io_end_vec, *tmp;
+
+	if (list_empty(&io_end->list_vec))
+		return;
+	list_for_each_entry_safe(io_end_vec, tmp, &io_end->list_vec, list) {
+		list_del(&io_end_vec->list);
+		kmem_cache_free(io_end_vec_cachep, io_end_vec);
+	}
+}
+
+struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end)
+{
+	BUG_ON(list_empty(&io_end->list_vec));
+	return list_last_entry(&io_end->list_vec, struct ext4_io_end_vec, list);
+}
+
+/*
+ * Print an buffer I/O error compatible with the fs/buffer.c.  This
+ * provides compatibility with dmesg scrapers that look for a specific
+ * buffer I/O error message.  We really need a unified error reporting
+ * structure to userspace ala Digital Unix's uerf system, but it's
+ * probably not going to happen in my lifetime, due to LKML politics...
+ */
+static void buffer_io_error(struct buffer_head *bh)
+{
+	printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n",
+		       bh->b_bdev,
+			(unsigned long long)bh->b_blocknr);
+}
+
+static void ext4_finish_bio(struct bio *bio)
+{
+	struct bio_vec *bvec;
+	struct bvec_iter_all iter_all;
+
+	bio_for_each_segment_all(bvec, bio, iter_all) {
+		struct page *page = bvec->bv_page;
+		struct page *bounce_page = NULL;
+		struct buffer_head *bh, *head;
+		unsigned bio_start = bvec->bv_offset;
+		unsigned bio_end = bio_start + bvec->bv_len;
+		unsigned under_io = 0;
+		unsigned long flags;
+
+		if (fscrypt_is_bounce_page(page)) {
+			bounce_page = page;
+			page = fscrypt_pagecache_page(bounce_page);
+		}
+
+		if (bio->bi_status) {
+			SetPageError(page);
+			mapping_set_error(page->mapping, -EIO);
+		}
+		bh = head = page_buffers(page);
+		/*
+		 * We check all buffers in the page under b_uptodate_lock
+		 * to avoid races with other end io clearing async_write flags
+		 */
+		spin_lock_irqsave(&head->b_uptodate_lock, flags);
+		do {
+			if (bh_offset(bh) < bio_start ||
+			    bh_offset(bh) + bh->b_size > bio_end) {
+				if (buffer_async_write(bh))
+					under_io++;
+				continue;
+			}
+			clear_buffer_async_write(bh);
+			if (bio->bi_status) {
+				set_buffer_write_io_error(bh);
+				buffer_io_error(bh);
+			}
+		} while ((bh = bh->b_this_page) != head);
+		spin_unlock_irqrestore(&head->b_uptodate_lock, flags);
+		if (!under_io) {
+			fscrypt_free_bounce_page(bounce_page);
+			end_page_writeback(page);
+		}
+	}
+}
+
+static void ext4_release_io_end(ext4_io_end_t *io_end)
+{
+	struct bio *bio, *next_bio;
+
+	BUG_ON(!list_empty(&io_end->list));
+	BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
+	WARN_ON(io_end->handle);
+
+	for (bio = io_end->bio; bio; bio = next_bio) {
+		next_bio = bio->bi_private;
+		ext4_finish_bio(bio);
+		bio_put(bio);
+	}
+	ext4_free_io_end_vec(io_end);
+	kmem_cache_free(io_end_cachep, io_end);
+}
+
+/*
+ * Check a range of space and convert unwritten extents to written. Note that
+ * we are protected from truncate touching same part of extent tree by the
+ * fact that truncate code waits for all DIO to finish (thus exclusion from
+ * direct IO is achieved) and also waits for PageWriteback bits. Thus we
+ * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
+ * completed (happens from ext4_free_ioend()).
+ */
+static int ext4_end_io_end(ext4_io_end_t *io_end)
+{
+	struct inode *inode = io_end->inode;
+	handle_t *handle = io_end->handle;
+	int ret = 0;
+
+	ext4_debug("ext4_end_io_nolock: io_end 0x%p from inode %lu,list->next 0x%p,"
+		   "list->prev 0x%p\n",
+		   io_end, inode->i_ino, io_end->list.next, io_end->list.prev);
+
+	io_end->handle = NULL;	/* Following call will use up the handle */
+	ret = ext4_convert_unwritten_io_end_vec(handle, io_end);
+	if (ret < 0 && !ext4_forced_shutdown(EXT4_SB(inode->i_sb))) {
+		ext4_msg(inode->i_sb, KERN_EMERG,
+			 "failed to convert unwritten extents to written "
+			 "extents -- potential data loss!  "
+			 "(inode %lu, error %d)", inode->i_ino, ret);
+	}
+	ext4_clear_io_unwritten_flag(io_end);
+	ext4_release_io_end(io_end);
+	return ret;
+}
+
+static void dump_completed_IO(struct inode *inode, struct list_head *head)
+{
+#ifdef	EXT4FS_DEBUG
+	struct list_head *cur, *before, *after;
+	ext4_io_end_t *io_end, *io_end0, *io_end1;
+
+	if (list_empty(head))
+		return;
+
+	ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
+	list_for_each_entry(io_end, head, list) {
+		cur = &io_end->list;
+		before = cur->prev;
+		io_end0 = container_of(before, ext4_io_end_t, list);
+		after = cur->next;
+		io_end1 = container_of(after, ext4_io_end_t, list);
+
+		ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
+			    io_end, inode->i_ino, io_end0, io_end1);
+	}
+#endif
+}
+
+/* Add the io_end to per-inode completed end_io list. */
+static void ext4_add_complete_io(ext4_io_end_t *io_end)
+{
+	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
+	struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
+	struct workqueue_struct *wq;
+	unsigned long flags;
+
+	/* Only reserved conversions from writeback should enter here */
+	WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
+	WARN_ON(!io_end->handle && sbi->s_journal);
+	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
+	wq = sbi->rsv_conversion_wq;
+	if (list_empty(&ei->i_rsv_conversion_list))
+		queue_work(wq, &ei->i_rsv_conversion_work);
+	list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
+	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
+}
+
+static int ext4_do_flush_completed_IO(struct inode *inode,
+				      struct list_head *head)
+{
+	ext4_io_end_t *io_end;
+	struct list_head unwritten;
+	unsigned long flags;
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	int err, ret = 0;
+
+	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
+	dump_completed_IO(inode, head);
+	list_replace_init(head, &unwritten);
+	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
+
+	while (!list_empty(&unwritten)) {
+		io_end = list_entry(unwritten.next, ext4_io_end_t, list);
+		BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
+		list_del_init(&io_end->list);
+
+		err = ext4_end_io_end(io_end);
+		if (unlikely(!ret && err))
+			ret = err;
+	}
+	return ret;
+}
+
+/*
+ * work on completed IO, to convert unwritten extents to extents
+ */
+void ext4_end_io_rsv_work(struct work_struct *work)
+{
+	struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
+						  i_rsv_conversion_work);
+	ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
+}
+
+ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
+{
+	ext4_io_end_t *io_end = kmem_cache_zalloc(io_end_cachep, flags);
+
+	if (io_end) {
+		io_end->inode = inode;
+		INIT_LIST_HEAD(&io_end->list);
+		INIT_LIST_HEAD(&io_end->list_vec);
+		refcount_set(&io_end->count, 1);
+	}
+	return io_end;
+}
+
+void ext4_put_io_end_defer(ext4_io_end_t *io_end)
+{
+	if (refcount_dec_and_test(&io_end->count)) {
+		if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) ||
+				list_empty(&io_end->list_vec)) {
+			ext4_release_io_end(io_end);
+			return;
+		}
+		ext4_add_complete_io(io_end);
+	}
+}
+
+int ext4_put_io_end(ext4_io_end_t *io_end)
+{
+	int err = 0;
+
+	if (refcount_dec_and_test(&io_end->count)) {
+		if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
+			err = ext4_convert_unwritten_io_end_vec(io_end->handle,
+								io_end);
+			io_end->handle = NULL;
+			ext4_clear_io_unwritten_flag(io_end);
+		}
+		ext4_release_io_end(io_end);
+	}
+	return err;
+}
+
+ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
+{
+	refcount_inc(&io_end->count);
+	return io_end;
+}
+
+/* BIO completion function for page writeback */
+static void ext4_end_bio(struct bio *bio)
+{
+	ext4_io_end_t *io_end = bio->bi_private;
+	sector_t bi_sector = bio->bi_iter.bi_sector;
+
+	if (WARN_ONCE(!io_end, "io_end is NULL: %pg: sector %Lu len %u err %d\n",
+		      bio->bi_bdev,
+		      (long long) bio->bi_iter.bi_sector,
+		      (unsigned) bio_sectors(bio),
+		      bio->bi_status)) {
+		ext4_finish_bio(bio);
+		bio_put(bio);
+		return;
+	}
+	bio->bi_end_io = NULL;
+
+	if (bio->bi_status) {
+		struct inode *inode = io_end->inode;
+
+		ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
+			     "starting block %llu)",
+			     bio->bi_status, inode->i_ino,
+			     (unsigned long long)
+			     bi_sector >> (inode->i_blkbits - 9));
+		mapping_set_error(inode->i_mapping,
+				blk_status_to_errno(bio->bi_status));
+	}
+
+	if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
+		/*
+		 * Link bio into list hanging from io_end. We have to do it
+		 * atomically as bio completions can be racing against each
+		 * other.
+		 */
+		bio->bi_private = xchg(&io_end->bio, bio);
+		ext4_put_io_end_defer(io_end);
+	} else {
+		/*
+		 * Drop io_end reference early. Inode can get freed once
+		 * we finish the bio.
+		 */
+		ext4_put_io_end_defer(io_end);
+		ext4_finish_bio(bio);
+		bio_put(bio);
+	}
+}
+
+void ext4_io_submit(struct ext4_io_submit *io)
+{
+	struct bio *bio = io->io_bio;
+
+	if (bio) {
+		if (io->io_wbc->sync_mode == WB_SYNC_ALL)
+			io->io_bio->bi_opf |= REQ_SYNC;
+		submit_bio(io->io_bio);
+	}
+	io->io_bio = NULL;
+}
+
+void ext4_io_submit_init(struct ext4_io_submit *io,
+			 struct writeback_control *wbc)
+{
+	io->io_wbc = wbc;
+	io->io_bio = NULL;
+	io->io_end = NULL;
+}
+
+static void io_submit_init_bio(struct ext4_io_submit *io,
+			       struct buffer_head *bh)
+{
+	struct bio *bio;
+
+	/*
+	 * bio_alloc will _always_ be able to allocate a bio if
+	 * __GFP_DIRECT_RECLAIM is set, see comments for bio_alloc_bioset().
+	 */
+	bio = bio_alloc(bh->b_bdev, BIO_MAX_VECS, REQ_OP_WRITE, GFP_NOIO);
+	fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
+	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+	bio->bi_end_io = ext4_end_bio;
+	bio->bi_private = ext4_get_io_end(io->io_end);
+	io->io_bio = bio;
+	io->io_next_block = bh->b_blocknr;
+	wbc_init_bio(io->io_wbc, bio);
+}
+
+static void io_submit_add_bh(struct ext4_io_submit *io,
+			     struct inode *inode,
+			     struct page *pagecache_page,
+			     struct page *bounce_page,
+			     struct buffer_head *bh)
+{
+	int ret;
+
+	if (io->io_bio && (bh->b_blocknr != io->io_next_block ||
+			   !fscrypt_mergeable_bio_bh(io->io_bio, bh))) {
+submit_and_retry:
+		ext4_io_submit(io);
+	}
+	if (io->io_bio == NULL)
+		io_submit_init_bio(io, bh);
+	ret = bio_add_page(io->io_bio, bounce_page ?: pagecache_page,
+			   bh->b_size, bh_offset(bh));
+	if (ret != bh->b_size)
+		goto submit_and_retry;
+	wbc_account_cgroup_owner(io->io_wbc, pagecache_page, bh->b_size);
+	io->io_next_block++;
+}
+
+int ext4_bio_write_page(struct ext4_io_submit *io,
+			struct page *page,
+			int len,
+			bool keep_towrite)
+{
+	struct page *bounce_page = NULL;
+	struct inode *inode = page->mapping->host;
+	unsigned block_start;
+	struct buffer_head *bh, *head;
+	int ret = 0;
+	int nr_submitted = 0;
+	int nr_to_submit = 0;
+	struct writeback_control *wbc = io->io_wbc;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(PageWriteback(page));
+
+	if (keep_towrite)
+		set_page_writeback_keepwrite(page);
+	else
+		set_page_writeback(page);
+	ClearPageError(page);
+
+	/*
+	 * Comments copied from block_write_full_page:
+	 *
+	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * writepage invocation because it may be mmapped.  "A file is mapped
+	 * in multiples of the page size.  For a file that is not a multiple of
+	 * the page size, the remaining memory is zeroed when mapped, and
+	 * writes to that region are not written out to the file."
+	 */
+	if (len < PAGE_SIZE)
+		zero_user_segment(page, len, PAGE_SIZE);
+	/*
+	 * In the first loop we prepare and mark buffers to submit. We have to
+	 * mark all buffers in the page before submitting so that
+	 * end_page_writeback() cannot be called from ext4_end_bio() when IO
+	 * on the first buffer finishes and we are still working on submitting
+	 * the second buffer.
+	 */
+	bh = head = page_buffers(page);
+	do {
+		block_start = bh_offset(bh);
+		if (block_start >= len) {
+			clear_buffer_dirty(bh);
+			set_buffer_uptodate(bh);
+			continue;
+		}
+		if (!buffer_dirty(bh) || buffer_delay(bh) ||
+		    !buffer_mapped(bh) || buffer_unwritten(bh)) {
+			/* A hole? We can safely clear the dirty bit */
+			if (!buffer_mapped(bh))
+				clear_buffer_dirty(bh);
+			if (io->io_bio)
+				ext4_io_submit(io);
+			continue;
+		}
+		if (buffer_new(bh))
+			clear_buffer_new(bh);
+		set_buffer_async_write(bh);
+		nr_to_submit++;
+	} while ((bh = bh->b_this_page) != head);
+
+	bh = head = page_buffers(page);
+
+	/*
+	 * If any blocks are being written to an encrypted file, encrypt them
+	 * into a bounce page.  For simplicity, just encrypt until the last
+	 * block which might be needed.  This may cause some unneeded blocks
+	 * (e.g. holes) to be unnecessarily encrypted, but this is rare and
+	 * can't happen in the common case of blocksize == PAGE_SIZE.
+	 */
+	if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) {
+		gfp_t gfp_flags = GFP_NOFS;
+		unsigned int enc_bytes = round_up(len, i_blocksize(inode));
+
+		/*
+		 * Since bounce page allocation uses a mempool, we can only use
+		 * a waiting mask (i.e. request guaranteed allocation) on the
+		 * first page of the bio.  Otherwise it can deadlock.
+		 */
+		if (io->io_bio)
+			gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
+	retry_encrypt:
+		bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes,
+							       0, gfp_flags);
+		if (IS_ERR(bounce_page)) {
+			ret = PTR_ERR(bounce_page);
+			if (ret == -ENOMEM &&
+			    (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
+				gfp_t new_gfp_flags = GFP_NOFS;
+				if (io->io_bio)
+					ext4_io_submit(io);
+				else
+					new_gfp_flags |= __GFP_NOFAIL;
+				memalloc_retry_wait(gfp_flags);
+				gfp_flags = new_gfp_flags;
+				goto retry_encrypt;
+			}
+
+			printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
+			redirty_page_for_writepage(wbc, page);
+			do {
+				clear_buffer_async_write(bh);
+				bh = bh->b_this_page;
+			} while (bh != head);
+			goto unlock;
+		}
+	}
+
+	/* Now submit buffers to write */
+	do {
+		if (!buffer_async_write(bh))
+			continue;
+		io_submit_add_bh(io, inode, page, bounce_page, bh);
+		nr_submitted++;
+		clear_buffer_dirty(bh);
+	} while ((bh = bh->b_this_page) != head);
+
+unlock:
+	unlock_page(page);
+	/* Nothing submitted - we have to end page writeback */
+	if (!nr_submitted)
+		end_page_writeback(page);
+	return ret;
+}