Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 6182 insertions, 0 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
new file mode 100644
index 000000000..e00c50ea2
--- /dev/null
+++ b/fs/btrfs/tree-log.c
@@ -0,0 +1,6182 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/list_sort.h>
+#include <linux/iversion.h>
+#include "ctree.h"
+#include "tree-log.h"
+#include "disk-io.h"
+#include "locking.h"
+#include "print-tree.h"
+#include "backref.h"
+#include "compression.h"
+#include "qgroup.h"
+#include "inode-map.h"
+
+/* magic values for the inode_only field in btrfs_log_inode:
+ *
+ * LOG_INODE_ALL means to log everything
+ * LOG_INODE_EXISTS means to log just enough to recreate the inode
+ * during log replay
+ */
+#define LOG_INODE_ALL 0
+#define LOG_INODE_EXISTS 1
+#define LOG_OTHER_INODE 2
+
+/*
+ * directory trouble cases
+ *
+ * 1) on rename or unlink, if the inode being unlinked isn't in the fsync
+ * log, we must force a full commit before doing an fsync of the directory
+ * where the unlink was done.
+ * ---> record transid of last unlink/rename per directory
+ *
+ * mkdir foo/some_dir
+ * normal commit
+ * rename foo/some_dir foo2/some_dir
+ * mkdir foo/some_dir
+ * fsync foo/some_dir/some_file
+ *
+ * The fsync above will unlink the original some_dir without recording
+ * it in its new location (foo2).  After a crash, some_dir will be gone
+ * unless the fsync of some_file forces a full commit
+ *
+ * 2) we must log any new names for any file or dir that is in the fsync
+ * log. ---> check inode while renaming/linking.
+ *
+ * 2a) we must log any new names for any file or dir during rename
+ * when the directory they are being removed from was logged.
+ * ---> check inode and old parent dir during rename
+ *
+ *  2a is actually the more important variant.  With the extra logging
+ *  a crash might unlink the old name without recreating the new one
+ *
+ * 3) after a crash, we must go through any directories with a link count
+ * of zero and redo the rm -rf
+ *
+ * mkdir f1/foo
+ * normal commit
+ * rm -rf f1/foo
+ * fsync(f1)
+ *
+ * The directory f1 was fully removed from the FS, but fsync was never
+ * called on f1, only its parent dir.  After a crash the rm -rf must
+ * be replayed.  This must be able to recurse down the entire
+ * directory tree.  The inode link count fixup code takes care of the
+ * ugly details.
+ */
+
+/*
+ * stages for the tree walking.  The first
+ * stage (0) is to only pin down the blocks we find
+ * the second stage (1) is to make sure that all the inodes
+ * we find in the log are created in the subvolume.
+ *
+ * The last stage is to deal with directories and links and extents
+ * and all the other fun semantics
+ */
+#define LOG_WALK_PIN_ONLY 0
+#define LOG_WALK_REPLAY_INODES 1
+#define LOG_WALK_REPLAY_DIR_INDEX 2
+#define LOG_WALK_REPLAY_ALL 3
+
+static int btrfs_log_inode(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root, struct btrfs_inode *inode,
+			   int inode_only,
+			   const loff_t start,
+			   const loff_t end,
+			   struct btrfs_log_ctx *ctx);
+static int link_to_fixup_dir(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root,
+			     struct btrfs_path *path, u64 objectid);
+static noinline int replay_dir_deletes(struct btrfs_trans_handle *trans,
+				       struct btrfs_root *root,
+				       struct btrfs_root *log,
+				       struct btrfs_path *path,
+				       u64 dirid, int del_all);
+
+/*
+ * tree logging is a special write ahead log used to make sure that
+ * fsyncs and O_SYNCs can happen without doing full tree commits.
+ *
+ * Full tree commits are expensive because they require commonly
+ * modified blocks to be recowed, creating many dirty pages in the
+ * extent tree an 4x-6x higher write load than ext3.
+ *
+ * Instead of doing a tree commit on every fsync, we use the
+ * key ranges and transaction ids to find items for a given file or directory
+ * that have changed in this transaction.  Those items are copied into
+ * a special tree (one per subvolume root), that tree is written to disk
+ * and then the fsync is considered complete.
+ *
+ * After a crash, items are copied out of the log-tree back into the
+ * subvolume tree.  Any file data extents found are recorded in the extent
+ * allocation tree, and the log-tree freed.
+ *
+ * The log tree is read three times, once to pin down all the extents it is
+ * using in ram and once, once to create all the inodes logged in the tree
+ * and once to do all the other items.
+ */
+
+/*
+ * start a sub transaction and setup the log tree
+ * this increments the log tree writer count to make the people
+ * syncing the tree wait for us to finish
+ */
+static int start_log_trans(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root,
+			   struct btrfs_log_ctx *ctx)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret = 0;
+
+	mutex_lock(&root->log_mutex);
+
+	if (root->log_root) {
+		if (btrfs_need_log_full_commit(fs_info, trans)) {
+			ret = -EAGAIN;
+			goto out;
+		}
+
+		if (!root->log_start_pid) {
+			clear_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
+			root->log_start_pid = current->pid;
+		} else if (root->log_start_pid != current->pid) {
+			set_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
+		}
+	} else {
+		mutex_lock(&fs_info->tree_log_mutex);
+		if (!fs_info->log_root_tree)
+			ret = btrfs_init_log_root_tree(trans, fs_info);
+		mutex_unlock(&fs_info->tree_log_mutex);
+		if (ret)
+			goto out;
+
+		ret = btrfs_add_log_tree(trans, root);
+		if (ret)
+			goto out;
+
+		clear_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
+		root->log_start_pid = current->pid;
+	}
+
+	atomic_inc(&root->log_batch);
+	atomic_inc(&root->log_writers);
+	if (ctx) {
+		int index = root->log_transid % 2;
+		list_add_tail(&ctx->list, &root->log_ctxs[index]);
+		ctx->log_transid = root->log_transid;
+	}
+
+out:
+	mutex_unlock(&root->log_mutex);
+	return ret;
+}
+
+/*
+ * returns 0 if there was a log transaction running and we were able
+ * to join, or returns -ENOENT if there were not transactions
+ * in progress
+ */
+static int join_running_log_trans(struct btrfs_root *root)
+{
+	int ret = -ENOENT;
+
+	smp_mb();
+	if (!root->log_root)
+		return -ENOENT;
+
+	mutex_lock(&root->log_mutex);
+	if (root->log_root) {
+		ret = 0;
+		atomic_inc(&root->log_writers);
+	}
+	mutex_unlock(&root->log_mutex);
+	return ret;
+}
+
+/*
+ * This either makes the current running log transaction wait
+ * until you call btrfs_end_log_trans() or it makes any future
+ * log transactions wait until you call btrfs_end_log_trans()
+ */
+int btrfs_pin_log_trans(struct btrfs_root *root)
+{
+	int ret = -ENOENT;
+
+	mutex_lock(&root->log_mutex);
+	atomic_inc(&root->log_writers);
+	mutex_unlock(&root->log_mutex);
+	return ret;
+}
+
+/*
+ * indicate we're done making changes to the log tree
+ * and wake up anyone waiting to do a sync
+ */
+void btrfs_end_log_trans(struct btrfs_root *root)
+{
+	if (atomic_dec_and_test(&root->log_writers)) {
+		/* atomic_dec_and_test implies a barrier */
+		cond_wake_up_nomb(&root->log_writer_wait);
+	}
+}
+
+
+/*
+ * the walk control struct is used to pass state down the chain when
+ * processing the log tree.  The stage field tells us which part
+ * of the log tree processing we are currently doing.  The others
+ * are state fields used for that specific part
+ */
+struct walk_control {
+	/* should we free the extent on disk when done?  This is used
+	 * at transaction commit time while freeing a log tree
+	 */
+	int free;
+
+	/* should we write out the extent buffer?  This is used
+	 * while flushing the log tree to disk during a sync
+	 */
+	int write;
+
+	/* should we wait for the extent buffer io to finish?  Also used
+	 * while flushing the log tree to disk for a sync
+	 */
+	int wait;
+
+	/* pin only walk, we record which extents on disk belong to the
+	 * log trees
+	 */
+	int pin;
+
+	/* what stage of the replay code we're currently in */
+	int stage;
+
+	/*
+	 * Ignore any items from the inode currently being processed. Needs
+	 * to be set every time we find a BTRFS_INODE_ITEM_KEY and we are in
+	 * the LOG_WALK_REPLAY_INODES stage.
+	 */
+	bool ignore_cur_inode;
+
+	/* the root we are currently replaying */
+	struct btrfs_root *replay_dest;
+
+	/* the trans handle for the current replay */
+	struct btrfs_trans_handle *trans;
+
+	/* the function that gets used to process blocks we find in the
+	 * tree.  Note the extent_buffer might not be up to date when it is
+	 * passed in, and it must be checked or read if you need the data
+	 * inside it
+	 */
+	int (*process_func)(struct btrfs_root *log, struct extent_buffer *eb,
+			    struct walk_control *wc, u64 gen, int level);
+};
+
+/*
+ * process_func used to pin down extents, write them or wait on them
+ */
+static int process_one_buffer(struct btrfs_root *log,
+			      struct extent_buffer *eb,
+			      struct walk_control *wc, u64 gen, int level)
+{
+	struct btrfs_fs_info *fs_info = log->fs_info;
+	int ret = 0;
+
+	/*
+	 * If this fs is mixed then we need to be able to process the leaves to
+	 * pin down any logged extents, so we have to read the block.
+	 */
+	if (btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
+		ret = btrfs_read_buffer(eb, gen, level, NULL);
+		if (ret)
+			return ret;
+	}
+
+	if (wc->pin)
+		ret = btrfs_pin_extent_for_log_replay(fs_info, eb->start,
+						      eb->len);
+
+	if (!ret && btrfs_buffer_uptodate(eb, gen, 0)) {
+		if (wc->pin && btrfs_header_level(eb) == 0)
+			ret = btrfs_exclude_logged_extents(fs_info, eb);
+		if (wc->write)
+			btrfs_write_tree_block(eb);
+		if (wc->wait)
+			btrfs_wait_tree_block_writeback(eb);
+	}
+	return ret;
+}
+
+/*
+ * Item overwrite used by replay and tree logging.  eb, slot and key all refer
+ * to the src data we are copying out.
+ *
+ * root is the tree we are copying into, and path is a scratch
+ * path for use in this function (it should be released on entry and
+ * will be released on exit).
+ *
+ * If the key is already in the destination tree the existing item is
+ * overwritten.  If the existing item isn't big enough, it is extended.
+ * If it is too large, it is truncated.
+ *
+ * If the key isn't in the destination yet, a new item is inserted.
+ */
+static noinline int overwrite_item(struct btrfs_trans_handle *trans,
+				   struct btrfs_root *root,
+				   struct btrfs_path *path,
+				   struct extent_buffer *eb, int slot,
+				   struct btrfs_key *key)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+	u32 item_size;
+	u64 saved_i_size = 0;
+	int save_old_i_size = 0;
+	unsigned long src_ptr;
+	unsigned long dst_ptr;
+	int overwrite_root = 0;
+	bool inode_item = key->type == BTRFS_INODE_ITEM_KEY;
+
+	if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID)
+		overwrite_root = 1;
+
+	item_size = btrfs_item_size_nr(eb, slot);
+	src_ptr = btrfs_item_ptr_offset(eb, slot);
+
+	/* look for the key in the destination tree */
+	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+	if (ret < 0)
+		return ret;
+
+	if (ret == 0) {
+		char *src_copy;
+		char *dst_copy;
+		u32 dst_size = btrfs_item_size_nr(path->nodes[0],
+						  path->slots[0]);
+		if (dst_size != item_size)
+			goto insert;
+
+		if (item_size == 0) {
+			btrfs_release_path(path);
+			return 0;
+		}
+		dst_copy = kmalloc(item_size, GFP_NOFS);
+		src_copy = kmalloc(item_size, GFP_NOFS);
+		if (!dst_copy || !src_copy) {
+			btrfs_release_path(path);
+			kfree(dst_copy);
+			kfree(src_copy);
+			return -ENOMEM;
+		}
+
+		read_extent_buffer(eb, src_copy, src_ptr, item_size);
+
+		dst_ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
+		read_extent_buffer(path->nodes[0], dst_copy, dst_ptr,
+				   item_size);
+		ret = memcmp(dst_copy, src_copy, item_size);
+
+		kfree(dst_copy);
+		kfree(src_copy);
+		/*
+		 * they have the same contents, just return, this saves
+		 * us from cowing blocks in the destination tree and doing
+		 * extra writes that may not have been done by a previous
+		 * sync
+		 */
+		if (ret == 0) {
+			btrfs_release_path(path);
+			return 0;
+		}
+
+		/*
+		 * We need to load the old nbytes into the inode so when we
+		 * replay the extents we've logged we get the right nbytes.
+		 */
+		if (inode_item) {
+			struct btrfs_inode_item *item;
+			u64 nbytes;
+			u32 mode;
+
+			item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+					      struct btrfs_inode_item);
+			nbytes = btrfs_inode_nbytes(path->nodes[0], item);
+			item = btrfs_item_ptr(eb, slot,
+					      struct btrfs_inode_item);
+			btrfs_set_inode_nbytes(eb, item, nbytes);
+
+			/*
+			 * If this is a directory we need to reset the i_size to
+			 * 0 so that we can set it up properly when replaying
+			 * the rest of the items in this log.
+			 */
+			mode = btrfs_inode_mode(eb, item);
+			if (S_ISDIR(mode))
+				btrfs_set_inode_size(eb, item, 0);
+		}
+	} else if (inode_item) {
+		struct btrfs_inode_item *item;
+		u32 mode;
+
+		/*
+		 * New inode, set nbytes to 0 so that the nbytes comes out
+		 * properly when we replay the extents.
+		 */
+		item = btrfs_item_ptr(eb, slot, struct btrfs_inode_item);
+		btrfs_set_inode_nbytes(eb, item, 0);
+
+		/*
+		 * If this is a directory we need to reset the i_size to 0 so
+		 * that we can set it up properly when replaying the rest of
+		 * the items in this log.
+		 */
+		mode = btrfs_inode_mode(eb, item);
+		if (S_ISDIR(mode))
+			btrfs_set_inode_size(eb, item, 0);
+	}
+insert:
+	btrfs_release_path(path);
+	/* try to insert the key into the destination tree */
+	path->skip_release_on_error = 1;
+	ret = btrfs_insert_empty_item(trans, root, path,
+				      key, item_size);
+	path->skip_release_on_error = 0;
+
+	/* make sure any existing item is the correct size */
+	if (ret == -EEXIST || ret == -EOVERFLOW) {
+		u32 found_size;
+		found_size = btrfs_item_size_nr(path->nodes[0],
+						path->slots[0]);
+		if (found_size > item_size)
+			btrfs_truncate_item(fs_info, path, item_size, 1);
+		else if (found_size < item_size)
+			btrfs_extend_item(fs_info, path,
+					  item_size - found_size);
+	} else if (ret) {
+		return ret;
+	}
+	dst_ptr = btrfs_item_ptr_offset(path->nodes[0],
+					path->slots[0]);
+
+	/* don't overwrite an existing inode if the generation number
+	 * was logged as zero.  This is done when the tree logging code
+	 * is just logging an inode to make sure it exists after recovery.
+	 *
+	 * Also, don't overwrite i_size on directories during replay.
+	 * log replay inserts and removes directory items based on the
+	 * state of the tree found in the subvolume, and i_size is modified
+	 * as it goes
+	 */
+	if (key->type == BTRFS_INODE_ITEM_KEY && ret == -EEXIST) {
+		struct btrfs_inode_item *src_item;
+		struct btrfs_inode_item *dst_item;
+
+		src_item = (struct btrfs_inode_item *)src_ptr;
+		dst_item = (struct btrfs_inode_item *)dst_ptr;
+
+		if (btrfs_inode_generation(eb, src_item) == 0) {
+			struct extent_buffer *dst_eb = path->nodes[0];
+			const u64 ino_size = btrfs_inode_size(eb, src_item);
+
+			/*
+			 * For regular files an ino_size == 0 is used only when
+			 * logging that an inode exists, as part of a directory
+			 * fsync, and the inode wasn't fsynced before. In this
+			 * case don't set the size of the inode in the fs/subvol
+			 * tree, otherwise we would be throwing valid data away.
+			 */
+			if (S_ISREG(btrfs_inode_mode(eb, src_item)) &&
+			    S_ISREG(btrfs_inode_mode(dst_eb, dst_item)) &&
+			    ino_size != 0) {
+				struct btrfs_map_token token;
+
+				btrfs_init_map_token(&token);
+				btrfs_set_token_inode_size(dst_eb, dst_item,
+							   ino_size, &token);
+			}
+			goto no_copy;
+		}
+
+		if (overwrite_root &&
+		    S_ISDIR(btrfs_inode_mode(eb, src_item)) &&
+		    S_ISDIR(btrfs_inode_mode(path->nodes[0], dst_item))) {
+			save_old_i_size = 1;
+			saved_i_size = btrfs_inode_size(path->nodes[0],
+							dst_item);
+		}
+	}
+
+	copy_extent_buffer(path->nodes[0], eb, dst_ptr,
+			   src_ptr, item_size);
+
+	if (save_old_i_size) {
+		struct btrfs_inode_item *dst_item;
+		dst_item = (struct btrfs_inode_item *)dst_ptr;
+		btrfs_set_inode_size(path->nodes[0], dst_item, saved_i_size);
+	}
+
+	/* make sure the generation is filled in */
+	if (key->type == BTRFS_INODE_ITEM_KEY) {
+		struct btrfs_inode_item *dst_item;
+		dst_item = (struct btrfs_inode_item *)dst_ptr;
+		if (btrfs_inode_generation(path->nodes[0], dst_item) == 0) {
+			btrfs_set_inode_generation(path->nodes[0], dst_item,
+						   trans->transid);
+		}
+	}
+no_copy:
+	btrfs_mark_buffer_dirty(path->nodes[0]);
+	btrfs_release_path(path);
+	return 0;
+}
+
+/*
+ * simple helper to read an inode off the disk from a given root
+ * This can only be called for subvolume roots and not for the log
+ */
+static noinline struct inode *read_one_inode(struct btrfs_root *root,
+					     u64 objectid)
+{
+	struct btrfs_key key;
+	struct inode *inode;
+
+	key.objectid = objectid;
+	key.type = BTRFS_INODE_ITEM_KEY;
+	key.offset = 0;
+	inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
+	if (IS_ERR(inode))
+		inode = NULL;
+	return inode;
+}
+
+/* replays a single extent in 'eb' at 'slot' with 'key' into the
+ * subvolume 'root'.  path is released on entry and should be released
+ * on exit.
+ *
+ * extents in the log tree have not been allocated out of the extent
+ * tree yet.  So, this completes the allocation, taking a reference
+ * as required if the extent already exists or creating a new extent
+ * if it isn't in the extent allocation tree yet.
+ *
+ * The extent is inserted into the file, dropping any existing extents
+ * from the file that overlap the new one.
+ */
+static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
+				      struct btrfs_root *root,
+				      struct btrfs_path *path,
+				      struct extent_buffer *eb, int slot,
+				      struct btrfs_key *key)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int found_type;
+	u64 extent_end;
+	u64 start = key->offset;
+	u64 nbytes = 0;
+	struct btrfs_file_extent_item *item;
+	struct inode *inode = NULL;
+	unsigned long size;
+	int ret = 0;
+
+	item = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
+	found_type = btrfs_file_extent_type(eb, item);
+
+	if (found_type == BTRFS_FILE_EXTENT_REG ||
+	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		nbytes = btrfs_file_extent_num_bytes(eb, item);
+		extent_end = start + nbytes;
+
+		/*
+		 * We don't add to the inodes nbytes if we are prealloc or a
+		 * hole.
+		 */
+		if (btrfs_file_extent_disk_bytenr(eb, item) == 0)
+			nbytes = 0;
+	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+		size = btrfs_file_extent_ram_bytes(eb, item);
+		nbytes = btrfs_file_extent_ram_bytes(eb, item);
+		extent_end = ALIGN(start + size,
+				   fs_info->sectorsize);
+	} else {
+		ret = 0;
+		goto out;
+	}
+
+	inode = read_one_inode(root, key->objectid);
+	if (!inode) {
+		ret = -EIO;
+		goto out;
+	}
+
+	/*
+	 * first check to see if we already have this extent in the
+	 * file.  This must be done before the btrfs_drop_extents run
+	 * so we don't try to drop this extent.
+	 */
+	ret = btrfs_lookup_file_extent(trans, root, path,
+			btrfs_ino(BTRFS_I(inode)), start, 0);
+
+	if (ret == 0 &&
+	    (found_type == BTRFS_FILE_EXTENT_REG ||
+	     found_type == BTRFS_FILE_EXTENT_PREALLOC)) {
+		struct btrfs_file_extent_item cmp1;
+		struct btrfs_file_extent_item cmp2;
+		struct btrfs_file_extent_item *existing;
+		struct extent_buffer *leaf;
+
+		leaf = path->nodes[0];
+		existing = btrfs_item_ptr(leaf, path->slots[0],
+					  struct btrfs_file_extent_item);
+
+		read_extent_buffer(eb, &cmp1, (unsigned long)item,
+				   sizeof(cmp1));
+		read_extent_buffer(leaf, &cmp2, (unsigned long)existing,
+				   sizeof(cmp2));
+
+		/*
+		 * we already have a pointer to this exact extent,
+		 * we don't have to do anything
+		 */
+		if (memcmp(&cmp1, &cmp2, sizeof(cmp1)) == 0) {
+			btrfs_release_path(path);
+			goto out;
+		}
+	}
+	btrfs_release_path(path);
+
+	/* drop any overlapping extents */
+	ret = btrfs_drop_extents(trans, root, inode, start, extent_end, 1);
+	if (ret)
+		goto out;
+
+	if (found_type == BTRFS_FILE_EXTENT_REG ||
+	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		u64 offset;
+		unsigned long dest_offset;
+		struct btrfs_key ins;
+
+		if (btrfs_file_extent_disk_bytenr(eb, item) == 0 &&
+		    btrfs_fs_incompat(fs_info, NO_HOLES))
+			goto update_inode;
+
+		ret = btrfs_insert_empty_item(trans, root, path, key,
+					      sizeof(*item));
+		if (ret)
+			goto out;
+		dest_offset = btrfs_item_ptr_offset(path->nodes[0],
+						    path->slots[0]);
+		copy_extent_buffer(path->nodes[0], eb, dest_offset,
+				(unsigned long)item,  sizeof(*item));
+
+		ins.objectid = btrfs_file_extent_disk_bytenr(eb, item);
+		ins.offset = btrfs_file_extent_disk_num_bytes(eb, item);
+		ins.type = BTRFS_EXTENT_ITEM_KEY;
+		offset = key->offset - btrfs_file_extent_offset(eb, item);
+
+		/*
+		 * Manually record dirty extent, as here we did a shallow
+		 * file extent item copy and skip normal backref update,
+		 * but modifying extent tree all by ourselves.
+		 * So need to manually record dirty extent for qgroup,
+		 * as the owner of the file extent changed from log tree
+		 * (doesn't affect qgroup) to fs/file tree(affects qgroup)
+		 */
+		ret = btrfs_qgroup_trace_extent(trans,
+				btrfs_file_extent_disk_bytenr(eb, item),
+				btrfs_file_extent_disk_num_bytes(eb, item),
+				GFP_NOFS);
+		if (ret < 0)
+			goto out;
+
+		if (ins.objectid > 0) {
+			u64 csum_start;
+			u64 csum_end;
+			LIST_HEAD(ordered_sums);
+			/*
+			 * is this extent already allocated in the extent
+			 * allocation tree?  If so, just add a reference
+			 */
+			ret = btrfs_lookup_data_extent(fs_info, ins.objectid,
+						ins.offset);
+			if (ret == 0) {
+				ret = btrfs_inc_extent_ref(trans, root,
+						ins.objectid, ins.offset,
+						0, root->root_key.objectid,
+						key->objectid, offset);
+				if (ret)
+					goto out;
+			} else {
+				/*
+				 * insert the extent pointer in the extent
+				 * allocation tree
+				 */
+				ret = btrfs_alloc_logged_file_extent(trans,
+						root->root_key.objectid,
+						key->objectid, offset, &ins);
+				if (ret)
+					goto out;
+			}
+			btrfs_release_path(path);
+
+			if (btrfs_file_extent_compression(eb, item)) {
+				csum_start = ins.objectid;
+				csum_end = csum_start + ins.offset;
+			} else {
+				csum_start = ins.objectid +
+					btrfs_file_extent_offset(eb, item);
+				csum_end = csum_start +
+					btrfs_file_extent_num_bytes(eb, item);
+			}
+
+			ret = btrfs_lookup_csums_range(root->log_root,
+						csum_start, csum_end - 1,
+						&ordered_sums, 0);
+			if (ret)
+				goto out;
+			/*
+			 * Now delete all existing cums in the csum root that
+			 * cover our range. We do this because we can have an
+			 * extent that is completely referenced by one file
+			 * extent item and partially referenced by another
+			 * file extent item (like after using the clone or
+			 * extent_same ioctls). In this case if we end up doing
+			 * the replay of the one that partially references the
+			 * extent first, and we do not do the csum deletion
+			 * below, we can get 2 csum items in the csum tree that
+			 * overlap each other. For example, imagine our log has
+			 * the two following file extent items:
+			 *
+			 * key (257 EXTENT_DATA 409600)
+			 *     extent data disk byte 12845056 nr 102400
+			 *     extent data offset 20480 nr 20480 ram 102400
+			 *
+			 * key (257 EXTENT_DATA 819200)
+			 *     extent data disk byte 12845056 nr 102400
+			 *     extent data offset 0 nr 102400 ram 102400
+			 *
+			 * Where the second one fully references the 100K extent
+			 * that starts at disk byte 12845056, and the log tree
+			 * has a single csum item that covers the entire range
+			 * of the extent:
+			 *
+			 * key (EXTENT_CSUM EXTENT_CSUM 12845056) itemsize 100
+			 *
+			 * After the first file extent item is replayed, the
+			 * csum tree gets the following csum item:
+			 *
+			 * key (EXTENT_CSUM EXTENT_CSUM 12865536) itemsize 20
+			 *
+			 * Which covers the 20K sub-range starting at offset 20K
+			 * of our extent. Now when we replay the second file
+			 * extent item, if we do not delete existing csum items
+			 * that cover any of its blocks, we end up getting two
+			 * csum items in our csum tree that overlap each other:
+			 *
+			 * key (EXTENT_CSUM EXTENT_CSUM 12845056) itemsize 100
+			 * key (EXTENT_CSUM EXTENT_CSUM 12865536) itemsize 20
+			 *
+			 * Which is a problem, because after this anyone trying
+			 * to lookup up for the checksum of any block of our
+			 * extent starting at an offset of 40K or higher, will
+			 * end up looking at the second csum item only, which
+			 * does not contain the checksum for any block starting
+			 * at offset 40K or higher of our extent.
+			 */
+			while (!list_empty(&ordered_sums)) {
+				struct btrfs_ordered_sum *sums;
+				sums = list_entry(ordered_sums.next,
+						struct btrfs_ordered_sum,
+						list);
+				if (!ret)
+					ret = btrfs_del_csums(trans,
+							      fs_info->csum_root,
+							      sums->bytenr,
+							      sums->len);
+				if (!ret)
+					ret = btrfs_csum_file_blocks(trans,
+						fs_info->csum_root, sums);
+				list_del(&sums->list);
+				kfree(sums);
+			}
+			if (ret)
+				goto out;
+		} else {
+			btrfs_release_path(path);
+		}
+	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+		/* inline extents are easy, we just overwrite them */
+		ret = overwrite_item(trans, root, path, eb, slot, key);
+		if (ret)
+			goto out;
+	}
+
+	inode_add_bytes(inode, nbytes);
+update_inode:
+	ret = btrfs_update_inode(trans, root, inode);
+out:
+	if (inode)
+		iput(inode);
+	return ret;
+}
+
+/*
+ * when cleaning up conflicts between the directory names in the
+ * subvolume, directory names in the log and directory names in the
+ * inode back references, we may have to unlink inodes from directories.
+ *
+ * This is a helper function to do the unlink of a specific directory
+ * item
+ */
+static noinline int drop_one_dir_item(struct btrfs_trans_handle *trans,
+				      struct btrfs_root *root,
+				      struct btrfs_path *path,
+				      struct btrfs_inode *dir,
+				      struct btrfs_dir_item *di)
+{
+	struct inode *inode;
+	char *name;
+	int name_len;
+	struct extent_buffer *leaf;
+	struct btrfs_key location;
+	int ret;
+
+	leaf = path->nodes[0];
+
+	btrfs_dir_item_key_to_cpu(leaf, di, &location);
+	name_len = btrfs_dir_name_len(leaf, di);
+	name = kmalloc(name_len, GFP_NOFS);
+	if (!name)
+		return -ENOMEM;
+
+	read_extent_buffer(leaf, name, (unsigned long)(di + 1), name_len);
+	btrfs_release_path(path);
+
+	inode = read_one_inode(root, location.objectid);
+	if (!inode) {
+		ret = -EIO;
+		goto out;
+	}
+
+	ret = link_to_fixup_dir(trans, root, path, location.objectid);
+	if (ret)
+		goto out;
+
+	ret = btrfs_unlink_inode(trans, root, dir, BTRFS_I(inode), name,
+			name_len);
+	if (ret)
+		goto out;
+	else
+		ret = btrfs_run_delayed_items(trans);
+out:
+	kfree(name);
+	iput(inode);
+	return ret;
+}
+
+/*
+ * See if a given name and sequence number found in an inode back reference are
+ * already in a directory and correctly point to this inode.
+ *
+ * Returns: < 0 on error, 0 if the directory entry does not exists and 1 if it
+ * exists.
+ */
+static noinline int inode_in_dir(struct btrfs_root *root,
+				 struct btrfs_path *path,
+				 u64 dirid, u64 objectid, u64 index,
+				 const char *name, int name_len)
+{
+	struct btrfs_dir_item *di;
+	struct btrfs_key location;
+	int ret = 0;
+
+	di = btrfs_lookup_dir_index_item(NULL, root, path, dirid,
+					 index, name, name_len, 0);
+	if (IS_ERR(di)) {
+		if (PTR_ERR(di) != -ENOENT)
+			ret = PTR_ERR(di);
+		goto out;
+	} else if (di) {
+		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
+		if (location.objectid != objectid)
+			goto out;
+	} else {
+		goto out;
+	}
+
+	btrfs_release_path(path);
+	di = btrfs_lookup_dir_item(NULL, root, path, dirid, name, name_len, 0);
+	if (IS_ERR(di)) {
+		ret = PTR_ERR(di);
+		goto out;
+	} else if (di) {
+		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
+		if (location.objectid == objectid)
+			ret = 1;
+	}
+out:
+	btrfs_release_path(path);
+	return ret;
+}
+
+/*
+ * helper function to check a log tree for a named back reference in
+ * an inode.  This is used to decide if a back reference that is
+ * found in the subvolume conflicts with what we find in the log.
+ *
+ * inode backreferences may have multiple refs in a single item,
+ * during replay we process one reference at a time, and we don't
+ * want to delete valid links to a file from the subvolume if that
+ * link is also in the log.
+ */
+static noinline int backref_in_log(struct btrfs_root *log,
+				   struct btrfs_key *key,
+				   u64 ref_objectid,
+				   const char *name, int namelen)
+{
+	struct btrfs_path *path;
+	struct btrfs_inode_ref *ref;
+	unsigned long ptr;
+	unsigned long ptr_end;
+	unsigned long name_ptr;
+	int found_name_len;
+	int item_size;
+	int ret;
+	int match = 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_search_slot(NULL, log, key, path, 0, 0);
+	if (ret != 0)
+		goto out;
+
+	ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
+
+	if (key->type == BTRFS_INODE_EXTREF_KEY) {
+		if (btrfs_find_name_in_ext_backref(path->nodes[0],
+						   path->slots[0],
+						   ref_objectid,
+						   name, namelen, NULL))
+			match = 1;
+
+		goto out;
+	}
+
+	item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
+	ptr_end = ptr + item_size;
+	while (ptr < ptr_end) {
+		ref = (struct btrfs_inode_ref *)ptr;
+		found_name_len = btrfs_inode_ref_name_len(path->nodes[0], ref);
+		if (found_name_len == namelen) {
+			name_ptr = (unsigned long)(ref + 1);
+			ret = memcmp_extent_buffer(path->nodes[0], name,
+						   name_ptr, namelen);
+			if (ret == 0) {
+				match = 1;
+				goto out;
+			}
+		}
+		ptr = (unsigned long)(ref + 1) + found_name_len;
+	}
+out:
+	btrfs_free_path(path);
+	return match;
+}
+
+static inline int __add_inode_ref(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root,
+				  struct btrfs_path *path,
+				  struct btrfs_root *log_root,
+				  struct btrfs_inode *dir,
+				  struct btrfs_inode *inode,
+				  u64 inode_objectid, u64 parent_objectid,
+				  u64 ref_index, char *name, int namelen,
+				  int *search_done)
+{
+	int ret;
+	char *victim_name;
+	int victim_name_len;
+	struct extent_buffer *leaf;
+	struct btrfs_dir_item *di;
+	struct btrfs_key search_key;
+	struct btrfs_inode_extref *extref;
+
+again:
+	/* Search old style refs */
+	search_key.objectid = inode_objectid;
+	search_key.type = BTRFS_INODE_REF_KEY;
+	search_key.offset = parent_objectid;
+	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
+	if (ret == 0) {
+		struct btrfs_inode_ref *victim_ref;
+		unsigned long ptr;
+		unsigned long ptr_end;
+
+		leaf = path->nodes[0];
+
+		/* are we trying to overwrite a back ref for the root directory
+		 * if so, just jump out, we're done
+		 */
+		if (search_key.objectid == search_key.offset)
+			return 1;
+
+		/* check all the names in this back reference to see
+		 * if they are in the log.  if so, we allow them to stay
+		 * otherwise they must be unlinked as a conflict
+		 */
+		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+		ptr_end = ptr + btrfs_item_size_nr(leaf, path->slots[0]);
+		while (ptr < ptr_end) {
+			victim_ref = (struct btrfs_inode_ref *)ptr;
+			victim_name_len = btrfs_inode_ref_name_len(leaf,
+								   victim_ref);
+			victim_name = kmalloc(victim_name_len, GFP_NOFS);
+			if (!victim_name)
+				return -ENOMEM;
+
+			read_extent_buffer(leaf, victim_name,
+					   (unsigned long)(victim_ref + 1),
+					   victim_name_len);
+
+			if (!backref_in_log(log_root, &search_key,
+					    parent_objectid,
+					    victim_name,
+					    victim_name_len)) {
+				inc_nlink(&inode->vfs_inode);
+				btrfs_release_path(path);
+
+				ret = btrfs_unlink_inode(trans, root, dir, inode,
+						victim_name, victim_name_len);
+				kfree(victim_name);
+				if (ret)
+					return ret;
+				ret = btrfs_run_delayed_items(trans);
+				if (ret)
+					return ret;
+				*search_done = 1;
+				goto again;
+			}
+			kfree(victim_name);
+
+			ptr = (unsigned long)(victim_ref + 1) + victim_name_len;
+		}
+
+		/*
+		 * NOTE: we have searched root tree and checked the
+		 * corresponding ref, it does not need to check again.
+		 */
+		*search_done = 1;
+	}
+	btrfs_release_path(path);
+
+	/* Same search but for extended refs */
+	extref = btrfs_lookup_inode_extref(NULL, root, path, name, namelen,
+					   inode_objectid, parent_objectid, 0,
+					   0);
+	if (!IS_ERR_OR_NULL(extref)) {
+		u32 item_size;
+		u32 cur_offset = 0;
+		unsigned long base;
+		struct inode *victim_parent;
+
+		leaf = path->nodes[0];
+
+		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+		base = btrfs_item_ptr_offset(leaf, path->slots[0]);
+
+		while (cur_offset < item_size) {
+			extref = (struct btrfs_inode_extref *)(base + cur_offset);
+
+			victim_name_len = btrfs_inode_extref_name_len(leaf, extref);
+
+			if (btrfs_inode_extref_parent(leaf, extref) != parent_objectid)
+				goto next;
+
+			victim_name = kmalloc(victim_name_len, GFP_NOFS);
+			if (!victim_name)
+				return -ENOMEM;
+			read_extent_buffer(leaf, victim_name, (unsigned long)&extref->name,
+					   victim_name_len);
+
+			search_key.objectid = inode_objectid;
+			search_key.type = BTRFS_INODE_EXTREF_KEY;
+			search_key.offset = btrfs_extref_hash(parent_objectid,
+							      victim_name,
+							      victim_name_len);
+			ret = 0;
+			if (!backref_in_log(log_root, &search_key,
+					    parent_objectid, victim_name,
+					    victim_name_len)) {
+				ret = -ENOENT;
+				victim_parent = read_one_inode(root,
+						parent_objectid);
+				if (victim_parent) {
+					inc_nlink(&inode->vfs_inode);
+					btrfs_release_path(path);
+
+					ret = btrfs_unlink_inode(trans, root,
+							BTRFS_I(victim_parent),
+							inode,
+							victim_name,
+							victim_name_len);
+					if (!ret)
+						ret = btrfs_run_delayed_items(
+								  trans);
+				}
+				iput(victim_parent);
+				kfree(victim_name);
+				if (ret)
+					return ret;
+				*search_done = 1;
+				goto again;
+			}
+			kfree(victim_name);
+next:
+			cur_offset += victim_name_len + sizeof(*extref);
+		}
+		*search_done = 1;
+	}
+	btrfs_release_path(path);
+
+	/* look for a conflicting sequence number */
+	di = btrfs_lookup_dir_index_item(trans, root, path, btrfs_ino(dir),
+					 ref_index, name, namelen, 0);
+	if (IS_ERR(di)) {
+		if (PTR_ERR(di) != -ENOENT)
+			return PTR_ERR(di);
+	} else if (di) {
+		ret = drop_one_dir_item(trans, root, path, dir, di);
+		if (ret)
+			return ret;
+	}
+	btrfs_release_path(path);
+
+	/* look for a conflicing name */
+	di = btrfs_lookup_dir_item(trans, root, path, btrfs_ino(dir),
+				   name, namelen, 0);
+	if (IS_ERR(di)) {
+		return PTR_ERR(di);
+	} else if (di) {
+		ret = drop_one_dir_item(trans, root, path, dir, di);
+		if (ret)
+			return ret;
+	}
+	btrfs_release_path(path);
+
+	return 0;
+}
+
+static int extref_get_fields(struct extent_buffer *eb, unsigned long ref_ptr,
+			     u32 *namelen, char **name, u64 *index,
+			     u64 *parent_objectid)
+{
+	struct btrfs_inode_extref *extref;
+
+	extref = (struct btrfs_inode_extref *)ref_ptr;
+
+	*namelen = btrfs_inode_extref_name_len(eb, extref);
+	*name = kmalloc(*namelen, GFP_NOFS);
+	if (*name == NULL)
+		return -ENOMEM;
+
+	read_extent_buffer(eb, *name, (unsigned long)&extref->name,
+			   *namelen);
+
+	if (index)
+		*index = btrfs_inode_extref_index(eb, extref);
+	if (parent_objectid)
+		*parent_objectid = btrfs_inode_extref_parent(eb, extref);
+
+	return 0;
+}
+
+static int ref_get_fields(struct extent_buffer *eb, unsigned long ref_ptr,
+			  u32 *namelen, char **name, u64 *index)
+{
+	struct btrfs_inode_ref *ref;
+
+	ref = (struct btrfs_inode_ref *)ref_ptr;
+
+	*namelen = btrfs_inode_ref_name_len(eb, ref);
+	*name = kmalloc(*namelen, GFP_NOFS);
+	if (*name == NULL)
+		return -ENOMEM;
+
+	read_extent_buffer(eb, *name, (unsigned long)(ref + 1), *namelen);
+
+	if (index)
+		*index = btrfs_inode_ref_index(eb, ref);
+
+	return 0;
+}
+
+/*
+ * Take an inode reference item from the log tree and iterate all names from the
+ * inode reference item in the subvolume tree with the same key (if it exists).
+ * For any name that is not in the inode reference item from the log tree, do a
+ * proper unlink of that name (that is, remove its entry from the inode
+ * reference item and both dir index keys).
+ */
+static int unlink_old_inode_refs(struct btrfs_trans_handle *trans,
+				 struct btrfs_root *root,
+				 struct btrfs_path *path,
+				 struct btrfs_inode *inode,
+				 struct extent_buffer *log_eb,
+				 int log_slot,
+				 struct btrfs_key *key)
+{
+	int ret;
+	unsigned long ref_ptr;
+	unsigned long ref_end;
+	struct extent_buffer *eb;
+
+again:
+	btrfs_release_path(path);
+	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+	if (ret > 0) {
+		ret = 0;
+		goto out;
+	}
+	if (ret < 0)
+		goto out;
+
+	eb = path->nodes[0];
+	ref_ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
+	ref_end = ref_ptr + btrfs_item_size_nr(eb, path->slots[0]);
+	while (ref_ptr < ref_end) {
+		char *name = NULL;
+		int namelen;
+		u64 parent_id;
+
+		if (key->type == BTRFS_INODE_EXTREF_KEY) {
+			ret = extref_get_fields(eb, ref_ptr, &namelen, &name,
+						NULL, &parent_id);
+		} else {
+			parent_id = key->offset;
+			ret = ref_get_fields(eb, ref_ptr, &namelen, &name,
+					     NULL);
+		}
+		if (ret)
+			goto out;
+
+		if (key->type == BTRFS_INODE_EXTREF_KEY)
+			ret = btrfs_find_name_in_ext_backref(log_eb, log_slot,
+							     parent_id, name,
+							     namelen, NULL);
+		else
+			ret = btrfs_find_name_in_backref(log_eb, log_slot, name,
+							 namelen, NULL);
+
+		if (!ret) {
+			struct inode *dir;
+
+			btrfs_release_path(path);
+			dir = read_one_inode(root, parent_id);
+			if (!dir) {
+				ret = -ENOENT;
+				kfree(name);
+				goto out;
+			}
+			ret = btrfs_unlink_inode(trans, root, BTRFS_I(dir),
+						 inode, name, namelen);
+			kfree(name);
+			iput(dir);
+			/*
+			 * Whenever we need to check if a name exists or not, we
+			 * check the subvolume tree. So after an unlink we must
+			 * run delayed items, so that future checks for a name
+			 * during log replay see that the name does not exists
+			 * anymore.
+			 */
+			if (!ret)
+				ret = btrfs_run_delayed_items(trans);
+			if (ret)
+				goto out;
+			goto again;
+		}
+
+		kfree(name);
+		ref_ptr += namelen;
+		if (key->type == BTRFS_INODE_EXTREF_KEY)
+			ref_ptr += sizeof(struct btrfs_inode_extref);
+		else
+			ref_ptr += sizeof(struct btrfs_inode_ref);
+	}
+	ret = 0;
+ out:
+	btrfs_release_path(path);
+	return ret;
+}
+
+static int btrfs_inode_ref_exists(struct inode *inode, struct inode *dir,
+				  const u8 ref_type, const char *name,
+				  const int namelen)
+{
+	struct btrfs_key key;
+	struct btrfs_path *path;
+	const u64 parent_id = btrfs_ino(BTRFS_I(dir));
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+	key.type = ref_type;
+	if (key.type == BTRFS_INODE_REF_KEY)
+		key.offset = parent_id;
+	else
+		key.offset = btrfs_extref_hash(parent_id, name, namelen);
+
+	ret = btrfs_search_slot(NULL, BTRFS_I(inode)->root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+	if (ret > 0) {
+		ret = 0;
+		goto out;
+	}
+	if (key.type == BTRFS_INODE_EXTREF_KEY)
+		ret = btrfs_find_name_in_ext_backref(path->nodes[0],
+						     path->slots[0], parent_id,
+						     name, namelen, NULL);
+	else
+		ret = btrfs_find_name_in_backref(path->nodes[0], path->slots[0],
+						 name, namelen, NULL);
+
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * replay one inode back reference item found in the log tree.
+ * eb, slot and key refer to the buffer and key found in the log tree.
+ * root is the destination we are replaying into, and path is for temp
+ * use by this function.  (it should be released on return).
+ */
+static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root,
+				  struct btrfs_root *log,
+				  struct btrfs_path *path,
+				  struct extent_buffer *eb, int slot,
+				  struct btrfs_key *key)
+{
+	struct inode *dir = NULL;
+	struct inode *inode = NULL;
+	unsigned long ref_ptr;
+	unsigned long ref_end;
+	char *name = NULL;
+	int namelen;
+	int ret;
+	int search_done = 0;
+	int log_ref_ver = 0;
+	u64 parent_objectid;
+	u64 inode_objectid;
+	u64 ref_index = 0;
+	int ref_struct_size;
+
+	ref_ptr = btrfs_item_ptr_offset(eb, slot);
+	ref_end = ref_ptr + btrfs_item_size_nr(eb, slot);
+
+	if (key->type == BTRFS_INODE_EXTREF_KEY) {
+		struct btrfs_inode_extref *r;
+
+		ref_struct_size = sizeof(struct btrfs_inode_extref);
+		log_ref_ver = 1;
+		r = (struct btrfs_inode_extref *)ref_ptr;
+		parent_objectid = btrfs_inode_extref_parent(eb, r);
+	} else {
+		ref_struct_size = sizeof(struct btrfs_inode_ref);
+		parent_objectid = key->offset;
+	}
+	inode_objectid = key->objectid;
+
+	/*
+	 * it is possible that we didn't log all the parent directories
+	 * for a given inode.  If we don't find the dir, just don't
+	 * copy the back ref in.  The link count fixup code will take
+	 * care of the rest
+	 */
+	dir = read_one_inode(root, parent_objectid);
+	if (!dir) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	inode = read_one_inode(root, inode_objectid);
+	if (!inode) {
+		ret = -EIO;
+		goto out;
+	}
+
+	while (ref_ptr < ref_end) {
+		if (log_ref_ver) {
+			ret = extref_get_fields(eb, ref_ptr, &namelen, &name,
+						&ref_index, &parent_objectid);
+			/*
+			 * parent object can change from one array
+			 * item to another.
+			 */
+			if (!dir)
+				dir = read_one_inode(root, parent_objectid);
+			if (!dir) {
+				ret = -ENOENT;
+				goto out;
+			}
+		} else {
+			ret = ref_get_fields(eb, ref_ptr, &namelen, &name,
+					     &ref_index);
+		}
+		if (ret)
+			goto out;
+
+		ret = inode_in_dir(root, path, btrfs_ino(BTRFS_I(dir)),
+				   btrfs_ino(BTRFS_I(inode)), ref_index,
+				   name, namelen);
+		if (ret < 0) {
+			goto out;
+		} else if (ret == 0) {
+			/*
+			 * look for a conflicting back reference in the
+			 * metadata. if we find one we have to unlink that name
+			 * of the file before we add our new link.  Later on, we
+			 * overwrite any existing back reference, and we don't
+			 * want to create dangling pointers in the directory.
+			 */
+
+			if (!search_done) {
+				ret = __add_inode_ref(trans, root, path, log,
+						      BTRFS_I(dir),
+						      BTRFS_I(inode),
+						      inode_objectid,
+						      parent_objectid,
+						      ref_index, name, namelen,
+						      &search_done);
+				if (ret) {
+					if (ret == 1)
+						ret = 0;
+					goto out;
+				}
+			}
+
+			/*
+			 * If a reference item already exists for this inode
+			 * with the same parent and name, but different index,
+			 * drop it and the corresponding directory index entries
+			 * from the parent before adding the new reference item
+			 * and dir index entries, otherwise we would fail with
+			 * -EEXIST returned from btrfs_add_link() below.
+			 */
+			ret = btrfs_inode_ref_exists(inode, dir, key->type,
+						     name, namelen);
+			if (ret > 0) {
+				ret = btrfs_unlink_inode(trans, root,
+							 BTRFS_I(dir),
+							 BTRFS_I(inode),
+							 name, namelen);
+				/*
+				 * If we dropped the link count to 0, bump it so
+				 * that later the iput() on the inode will not
+				 * free it. We will fixup the link count later.
+				 */
+				if (!ret && inode->i_nlink == 0)
+					inc_nlink(inode);
+				/*
+				 * Whenever we need to check if a name exists or
+				 * not, we check the subvolume tree. So after an
+				 * unlink we must run delayed items, so that future
+				 * checks for a name during log replay see that the
+				 * name does not exists anymore.
+				 */
+				if (!ret)
+					ret = btrfs_run_delayed_items(trans);
+			}
+			if (ret < 0)
+				goto out;
+
+			/* insert our name */
+			ret = btrfs_add_link(trans, BTRFS_I(dir),
+					BTRFS_I(inode),
+					name, namelen, 0, ref_index);
+			if (ret)
+				goto out;
+
+			btrfs_update_inode(trans, root, inode);
+		}
+		/* Else, ret == 1, we already have a perfect match, we're done. */
+
+		ref_ptr = (unsigned long)(ref_ptr + ref_struct_size) + namelen;
+		kfree(name);
+		name = NULL;
+		if (log_ref_ver) {
+			iput(dir);
+			dir = NULL;
+		}
+	}
+
+	/*
+	 * Before we overwrite the inode reference item in the subvolume tree
+	 * with the item from the log tree, we must unlink all names from the
+	 * parent directory that are in the subvolume's tree inode reference
+	 * item, otherwise we end up with an inconsistent subvolume tree where
+	 * dir index entries exist for a name but there is no inode reference
+	 * item with the same name.
+	 */
+	ret = unlink_old_inode_refs(trans, root, path, BTRFS_I(inode), eb, slot,
+				    key);
+	if (ret)
+		goto out;
+
+	/* finally write the back reference in the inode */
+	ret = overwrite_item(trans, root, path, eb, slot, key);
+out:
+	btrfs_release_path(path);
+	kfree(name);
+	iput(dir);
+	iput(inode);
+	return ret;
+}
+
+static int insert_orphan_item(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root, u64 ino)
+{
+	int ret;
+
+	ret = btrfs_insert_orphan_item(trans, root, ino);
+	if (ret == -EEXIST)
+		ret = 0;
+
+	return ret;
+}
+
+static int count_inode_extrefs(struct btrfs_root *root,
+		struct btrfs_inode *inode, struct btrfs_path *path)
+{
+	int ret = 0;
+	int name_len;
+	unsigned int nlink = 0;
+	u32 item_size;
+	u32 cur_offset = 0;
+	u64 inode_objectid = btrfs_ino(inode);
+	u64 offset = 0;
+	unsigned long ptr;
+	struct btrfs_inode_extref *extref;
+	struct extent_buffer *leaf;
+
+	while (1) {
+		ret = btrfs_find_one_extref(root, inode_objectid, offset, path,
+					    &extref, &offset);
+		if (ret)
+			break;
+
+		leaf = path->nodes[0];
+		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+		cur_offset = 0;
+
+		while (cur_offset < item_size) {
+			extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
+			name_len = btrfs_inode_extref_name_len(leaf, extref);
+
+			nlink++;
+
+			cur_offset += name_len + sizeof(*extref);
+		}
+
+		offset++;
+		btrfs_release_path(path);
+	}
+	btrfs_release_path(path);
+
+	if (ret < 0 && ret != -ENOENT)
+		return ret;
+	return nlink;
+}
+
+static int count_inode_refs(struct btrfs_root *root,
+			struct btrfs_inode *inode, struct btrfs_path *path)
+{
+	int ret;
+	struct btrfs_key key;
+	unsigned int nlink = 0;
+	unsigned long ptr;
+	unsigned long ptr_end;
+	int name_len;
+	u64 ino = btrfs_ino(inode);
+
+	key.objectid = ino;
+	key.type = BTRFS_INODE_REF_KEY;
+	key.offset = (u64)-1;
+
+	while (1) {
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			break;
+		if (ret > 0) {
+			if (path->slots[0] == 0)
+				break;
+			path->slots[0]--;
+		}
+process_slot:
+		btrfs_item_key_to_cpu(path->nodes[0], &key,
+				      path->slots[0]);
+		if (key.objectid != ino ||
+		    key.type != BTRFS_INODE_REF_KEY)
+			break;
+		ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
+		ptr_end = ptr + btrfs_item_size_nr(path->nodes[0],
+						   path->slots[0]);
+		while (ptr < ptr_end) {
+			struct btrfs_inode_ref *ref;
+
+			ref = (struct btrfs_inode_ref *)ptr;
+			name_len = btrfs_inode_ref_name_len(path->nodes[0],
+							    ref);
+			ptr = (unsigned long)(ref + 1) + name_len;
+			nlink++;
+		}
+
+		if (key.offset == 0)
+			break;
+		if (path->slots[0] > 0) {
+			path->slots[0]--;
+			goto process_slot;
+		}
+		key.offset--;
+		btrfs_release_path(path);
+	}
+	btrfs_release_path(path);
+
+	return nlink;
+}
+
+/*
+ * There are a few corners where the link count of the file can't
+ * be properly maintained during replay.  So, instead of adding
+ * lots of complexity to the log code, we just scan the backrefs
+ * for any file that has been through replay.
+ *
+ * The scan will update the link count on the inode to reflect the
+ * number of back refs found.  If it goes down to zero, the iput
+ * will free the inode.
+ */
+static noinline int fixup_inode_link_count(struct btrfs_trans_handle *trans,
+					   struct btrfs_root *root,
+					   struct inode *inode)
+{
+	struct btrfs_path *path;
+	int ret;
+	u64 nlink = 0;
+	u64 ino = btrfs_ino(BTRFS_I(inode));
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = count_inode_refs(root, BTRFS_I(inode), path);
+	if (ret < 0)
+		goto out;
+
+	nlink = ret;
+
+	ret = count_inode_extrefs(root, BTRFS_I(inode), path);
+	if (ret < 0)
+		goto out;
+
+	nlink += ret;
+
+	ret = 0;
+
+	if (nlink != inode->i_nlink) {
+		set_nlink(inode, nlink);
+		btrfs_update_inode(trans, root, inode);
+	}
+	BTRFS_I(inode)->index_cnt = (u64)-1;
+
+	if (inode->i_nlink == 0) {
+		if (S_ISDIR(inode->i_mode)) {
+			ret = replay_dir_deletes(trans, root, NULL, path,
+						 ino, 1);
+			if (ret)
+				goto out;
+		}
+		ret = insert_orphan_item(trans, root, ino);
+	}
+
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static noinline int fixup_inode_link_counts(struct btrfs_trans_handle *trans,
+					    struct btrfs_root *root,
+					    struct btrfs_path *path)
+{
+	int ret;
+	struct btrfs_key key;
+	struct inode *inode;
+
+	key.objectid = BTRFS_TREE_LOG_FIXUP_OBJECTID;
+	key.type = BTRFS_ORPHAN_ITEM_KEY;
+	key.offset = (u64)-1;
+	while (1) {
+		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+		if (ret < 0)
+			break;
+
+		if (ret == 1) {
+			ret = 0;
+			if (path->slots[0] == 0)
+				break;
+			path->slots[0]--;
+		}
+
+		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+		if (key.objectid != BTRFS_TREE_LOG_FIXUP_OBJECTID ||
+		    key.type != BTRFS_ORPHAN_ITEM_KEY)
+			break;
+
+		ret = btrfs_del_item(trans, root, path);
+		if (ret)
+			break;
+
+		btrfs_release_path(path);
+		inode = read_one_inode(root, key.offset);
+		if (!inode) {
+			ret = -EIO;
+			break;
+		}
+
+		ret = fixup_inode_link_count(trans, root, inode);
+		iput(inode);
+		if (ret)
+			break;
+
+		/*
+		 * fixup on a directory may create new entries,
+		 * make sure we always look for the highset possible
+		 * offset
+		 */
+		key.offset = (u64)-1;
+	}
+	btrfs_release_path(path);
+	return ret;
+}
+
+
+/*
+ * record a given inode in the fixup dir so we can check its link
+ * count when replay is done.  The link count is incremented here
+ * so the inode won't go away until we check it
+ */
+static noinline int link_to_fixup_dir(struct btrfs_trans_handle *trans,
+				      struct btrfs_root *root,
+				      struct btrfs_path *path,
+				      u64 objectid)
+{
+	struct btrfs_key key;
+	int ret = 0;
+	struct inode *inode;
+
+	inode = read_one_inode(root, objectid);
+	if (!inode)
+		return -EIO;
+
+	key.objectid = BTRFS_TREE_LOG_FIXUP_OBJECTID;
+	key.type = BTRFS_ORPHAN_ITEM_KEY;
+	key.offset = objectid;
+
+	ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
+
+	btrfs_release_path(path);
+	if (ret == 0) {
+		if (!inode->i_nlink)
+			set_nlink(inode, 1);
+		else
+			inc_nlink(inode);
+		ret = btrfs_update_inode(trans, root, inode);
+	} else if (ret == -EEXIST) {
+		ret = 0;
+	}
+	iput(inode);
+
+	return ret;
+}
+
+/*
+ * when replaying the log for a directory, we only insert names
+ * for inodes that actually exist.  This means an fsync on a directory
+ * does not implicitly fsync all the new files in it
+ */
+static noinline int insert_one_name(struct btrfs_trans_handle *trans,
+				    struct btrfs_root *root,
+				    u64 dirid, u64 index,
+				    char *name, int name_len,
+				    struct btrfs_key *location)
+{
+	struct inode *inode;
+	struct inode *dir;
+	int ret;
+
+	inode = read_one_inode(root, location->objectid);
+	if (!inode)
+		return -ENOENT;
+
+	dir = read_one_inode(root, dirid);
+	if (!dir) {
+		iput(inode);
+		return -EIO;
+	}
+
+	ret = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode), name,
+			name_len, 1, index);
+
+	/* FIXME, put inode into FIXUP list */
+
+	iput(inode);
+	iput(dir);
+	return ret;
+}
+
+/*
+ * Return true if an inode reference exists in the log for the given name,
+ * inode and parent inode.
+ */
+static bool name_in_log_ref(struct btrfs_root *log_root,
+			    const char *name, const int name_len,
+			    const u64 dirid, const u64 ino)
+{
+	struct btrfs_key search_key;
+
+	search_key.objectid = ino;
+	search_key.type = BTRFS_INODE_REF_KEY;
+	search_key.offset = dirid;
+	if (backref_in_log(log_root, &search_key, dirid, name, name_len))
+		return true;
+
+	search_key.type = BTRFS_INODE_EXTREF_KEY;
+	search_key.offset = btrfs_extref_hash(dirid, name, name_len);
+	if (backref_in_log(log_root, &search_key, dirid, name, name_len))
+		return true;
+
+	return false;
+}
+
+/*
+ * take a single entry in a log directory item and replay it into
+ * the subvolume.
+ *
+ * if a conflicting item exists in the subdirectory already,
+ * the inode it points to is unlinked and put into the link count
+ * fix up tree.
+ *
+ * If a name from the log points to a file or directory that does
+ * not exist in the FS, it is skipped.  fsyncs on directories
+ * do not force down inodes inside that directory, just changes to the
+ * names or unlinks in a directory.
+ *
+ * Returns < 0 on error, 0 if the name wasn't replayed (dentry points to a
+ * non-existing inode) and 1 if the name was replayed.
+ */
+static noinline int replay_one_name(struct btrfs_trans_handle *trans,
+				    struct btrfs_root *root,
+				    struct btrfs_path *path,
+				    struct extent_buffer *eb,
+				    struct btrfs_dir_item *di,
+				    struct btrfs_key *key)
+{
+	char *name;
+	int name_len;
+	struct btrfs_dir_item *dst_di;
+	struct btrfs_key found_key;
+	struct btrfs_key log_key;
+	struct inode *dir;
+	u8 log_type;
+	bool exists;
+	int ret;
+	bool update_size = (key->type == BTRFS_DIR_INDEX_KEY);
+	bool name_added = false;
+
+	dir = read_one_inode(root, key->objectid);
+	if (!dir)
+		return -EIO;
+
+	name_len = btrfs_dir_name_len(eb, di);
+	name = kmalloc(name_len, GFP_NOFS);
+	if (!name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	log_type = btrfs_dir_type(eb, di);
+	read_extent_buffer(eb, name, (unsigned long)(di + 1),
+		   name_len);
+
+	btrfs_dir_item_key_to_cpu(eb, di, &log_key);
+	ret = btrfs_lookup_inode(trans, root, path, &log_key, 0);
+	btrfs_release_path(path);
+	if (ret < 0)
+		goto out;
+	exists = (ret == 0);
+	ret = 0;
+
+	if (key->type == BTRFS_DIR_ITEM_KEY) {
+		dst_di = btrfs_lookup_dir_item(trans, root, path, key->objectid,
+				       name, name_len, 1);
+	} else if (key->type == BTRFS_DIR_INDEX_KEY) {
+		dst_di = btrfs_lookup_dir_index_item(trans, root, path,
+						     key->objectid,
+						     key->offset, name,
+						     name_len, 1);
+	} else {
+		/* Corruption */
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (dst_di == ERR_PTR(-ENOENT))
+		dst_di = NULL;
+
+	if (IS_ERR(dst_di)) {
+		ret = PTR_ERR(dst_di);
+		goto out;
+	} else if (!dst_di) {
+		/* we need a sequence number to insert, so we only
+		 * do inserts for the BTRFS_DIR_INDEX_KEY types
+		 */
+		if (key->type != BTRFS_DIR_INDEX_KEY)
+			goto out;
+		goto insert;
+	}
+
+	btrfs_dir_item_key_to_cpu(path->nodes[0], dst_di, &found_key);
+	/* the existing item matches the logged item */
+	if (found_key.objectid == log_key.objectid &&
+	    found_key.type == log_key.type &&
+	    found_key.offset == log_key.offset &&
+	    btrfs_dir_type(path->nodes[0], dst_di) == log_type) {
+		update_size = false;
+		goto out;
+	}
+
+	/*
+	 * don't drop the conflicting directory entry if the inode
+	 * for the new entry doesn't exist
+	 */
+	if (!exists)
+		goto out;
+
+	ret = drop_one_dir_item(trans, root, path, BTRFS_I(dir), dst_di);
+	if (ret)
+		goto out;
+
+	if (key->type == BTRFS_DIR_INDEX_KEY)
+		goto insert;
+out:
+	btrfs_release_path(path);
+	if (!ret && update_size) {
+		btrfs_i_size_write(BTRFS_I(dir), dir->i_size + name_len * 2);
+		ret = btrfs_update_inode(trans, root, dir);
+	}
+	kfree(name);
+	iput(dir);
+	if (!ret && name_added)
+		ret = 1;
+	return ret;
+
+insert:
+	if (name_in_log_ref(root->log_root, name, name_len,
+			    key->objectid, log_key.objectid)) {
+		/* The dentry will be added later. */
+		ret = 0;
+		update_size = false;
+		goto out;
+	}
+	btrfs_release_path(path);
+	ret = insert_one_name(trans, root, key->objectid, key->offset,
+			      name, name_len, &log_key);
+	if (ret && ret != -ENOENT && ret != -EEXIST)
+		goto out;
+	if (!ret)
+		name_added = true;
+	update_size = false;
+	ret = 0;
+	goto out;
+}
+
+/*
+ * find all the names in a directory item and reconcile them into
+ * the subvolume.  Only BTRFS_DIR_ITEM_KEY types will have more than
+ * one name in a directory item, but the same code gets used for
+ * both directory index types
+ */
+static noinline int replay_one_dir_item(struct btrfs_trans_handle *trans,
+					struct btrfs_root *root,
+					struct btrfs_path *path,
+					struct extent_buffer *eb, int slot,
+					struct btrfs_key *key)
+{
+	int ret = 0;
+	u32 item_size = btrfs_item_size_nr(eb, slot);
+	struct btrfs_dir_item *di;
+	int name_len;
+	unsigned long ptr;
+	unsigned long ptr_end;
+	struct btrfs_path *fixup_path = NULL;
+
+	ptr = btrfs_item_ptr_offset(eb, slot);
+	ptr_end = ptr + item_size;
+	while (ptr < ptr_end) {
+		di = (struct btrfs_dir_item *)ptr;
+		name_len = btrfs_dir_name_len(eb, di);
+		ret = replay_one_name(trans, root, path, eb, di, key);
+		if (ret < 0)
+			break;
+		ptr = (unsigned long)(di + 1);
+		ptr += name_len;
+
+		/*
+		 * If this entry refers to a non-directory (directories can not
+		 * have a link count > 1) and it was added in the transaction
+		 * that was not committed, make sure we fixup the link count of
+		 * the inode it the entry points to. Otherwise something like
+		 * the following would result in a directory pointing to an
+		 * inode with a wrong link that does not account for this dir
+		 * entry:
+		 *
+		 * mkdir testdir
+		 * touch testdir/foo
+		 * touch testdir/bar
+		 * sync
+		 *
+		 * ln testdir/bar testdir/bar_link
+		 * ln testdir/foo testdir/foo_link
+		 * xfs_io -c "fsync" testdir/bar
+		 *
+		 * <power failure>
+		 *
+		 * mount fs, log replay happens
+		 *
+		 * File foo would remain with a link count of 1 when it has two
+		 * entries pointing to it in the directory testdir. This would
+		 * make it impossible to ever delete the parent directory has
+		 * it would result in stale dentries that can never be deleted.
+		 */
+		if (ret == 1 && btrfs_dir_type(eb, di) != BTRFS_FT_DIR) {
+			struct btrfs_key di_key;
+
+			if (!fixup_path) {
+				fixup_path = btrfs_alloc_path();
+				if (!fixup_path) {
+					ret = -ENOMEM;
+					break;
+				}
+			}
+
+			btrfs_dir_item_key_to_cpu(eb, di, &di_key);
+			ret = link_to_fixup_dir(trans, root, fixup_path,
+						di_key.objectid);
+			if (ret)
+				break;
+		}
+		ret = 0;
+	}
+	btrfs_free_path(fixup_path);
+	return ret;
+}
+
+/*
+ * directory replay has two parts.  There are the standard directory
+ * items in the log copied from the subvolume, and range items
+ * created in the log while the subvolume was logged.
+ *
+ * The range items tell us which parts of the key space the log
+ * is authoritative for.  During replay, if a key in the subvolume
+ * directory is in a logged range item, but not actually in the log
+ * that means it was deleted from the directory before the fsync
+ * and should be removed.
+ */
+static noinline int find_dir_range(struct btrfs_root *root,
+				   struct btrfs_path *path,
+				   u64 dirid, int key_type,
+				   u64 *start_ret, u64 *end_ret)
+{
+	struct btrfs_key key;
+	u64 found_end;
+	struct btrfs_dir_log_item *item;
+	int ret;
+	int nritems;
+
+	if (*start_ret == (u64)-1)
+		return 1;
+
+	key.objectid = dirid;
+	key.type = key_type;
+	key.offset = *start_ret;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+	if (ret > 0) {
+		if (path->slots[0] == 0)
+			goto out;
+		path->slots[0]--;
+	}
+	if (ret != 0)
+		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+
+	if (key.type != key_type || key.objectid != dirid) {
+		ret = 1;
+		goto next;
+	}
+	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			      struct btrfs_dir_log_item);
+	found_end = btrfs_dir_log_end(path->nodes[0], item);
+
+	if (*start_ret >= key.offset && *start_ret <= found_end) {
+		ret = 0;
+		*start_ret = key.offset;
+		*end_ret = found_end;
+		goto out;
+	}
+	ret = 1;
+next:
+	/* check the next slot in the tree to see if it is a valid item */
+	nritems = btrfs_header_nritems(path->nodes[0]);
+	path->slots[0]++;
+	if (path->slots[0] >= nritems) {
+		ret = btrfs_next_leaf(root, path);
+		if (ret)
+			goto out;
+	}
+
+	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+
+	if (key.type != key_type || key.objectid != dirid) {
+		ret = 1;
+		goto out;
+	}
+	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			      struct btrfs_dir_log_item);
+	found_end = btrfs_dir_log_end(path->nodes[0], item);
+	*start_ret = key.offset;
+	*end_ret = found_end;
+	ret = 0;
+out:
+	btrfs_release_path(path);
+	return ret;
+}
+
+/*
+ * this looks for a given directory item in the log.  If the directory
+ * item is not in the log, the item is removed and the inode it points
+ * to is unlinked
+ */
+static noinline int check_item_in_log(struct btrfs_trans_handle *trans,
+				      struct btrfs_root *root,
+				      struct btrfs_root *log,
+				      struct btrfs_path *path,
+				      struct btrfs_path *log_path,
+				      struct inode *dir,
+				      struct btrfs_key *dir_key)
+{
+	int ret;
+	struct extent_buffer *eb;
+	int slot;
+	u32 item_size;
+	struct btrfs_dir_item *di;
+	struct btrfs_dir_item *log_di;
+	int name_len;
+	unsigned long ptr;
+	unsigned long ptr_end;
+	char *name;
+	struct inode *inode;
+	struct btrfs_key location;
+
+again:
+	eb = path->nodes[0];
+	slot = path->slots[0];
+	item_size = btrfs_item_size_nr(eb, slot);
+	ptr = btrfs_item_ptr_offset(eb, slot);
+	ptr_end = ptr + item_size;
+	while (ptr < ptr_end) {
+		di = (struct btrfs_dir_item *)ptr;
+		name_len = btrfs_dir_name_len(eb, di);
+		name = kmalloc(name_len, GFP_NOFS);
+		if (!name) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		read_extent_buffer(eb, name, (unsigned long)(di + 1),
+				  name_len);
+		log_di = NULL;
+		if (log && dir_key->type == BTRFS_DIR_ITEM_KEY) {
+			log_di = btrfs_lookup_dir_item(trans, log, log_path,
+						       dir_key->objectid,
+						       name, name_len, 0);
+		} else if (log && dir_key->type == BTRFS_DIR_INDEX_KEY) {
+			log_di = btrfs_lookup_dir_index_item(trans, log,
+						     log_path,
+						     dir_key->objectid,
+						     dir_key->offset,
+						     name, name_len, 0);
+		}
+		if (!log_di || log_di == ERR_PTR(-ENOENT)) {
+			btrfs_dir_item_key_to_cpu(eb, di, &location);
+			btrfs_release_path(path);
+			btrfs_release_path(log_path);
+			inode = read_one_inode(root, location.objectid);
+			if (!inode) {
+				kfree(name);
+				return -EIO;
+			}
+
+			ret = link_to_fixup_dir(trans, root,
+						path, location.objectid);
+			if (ret) {
+				kfree(name);
+				iput(inode);
+				goto out;
+			}
+
+			inc_nlink(inode);
+			ret = btrfs_unlink_inode(trans, root, BTRFS_I(dir),
+					BTRFS_I(inode), name, name_len);
+			if (!ret)
+				ret = btrfs_run_delayed_items(trans);
+			kfree(name);
+			iput(inode);
+			if (ret)
+				goto out;
+
+			/* there might still be more names under this key
+			 * check and repeat if required
+			 */
+			ret = btrfs_search_slot(NULL, root, dir_key, path,
+						0, 0);
+			if (ret == 0)
+				goto again;
+			ret = 0;
+			goto out;
+		} else if (IS_ERR(log_di)) {
+			kfree(name);
+			return PTR_ERR(log_di);
+		}
+		btrfs_release_path(log_path);
+		kfree(name);
+
+		ptr = (unsigned long)(di + 1);
+		ptr += name_len;
+	}
+	ret = 0;
+out:
+	btrfs_release_path(path);
+	btrfs_release_path(log_path);
+	return ret;
+}
+
+static int replay_xattr_deletes(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root,
+			      struct btrfs_root *log,
+			      struct btrfs_path *path,
+			      const u64 ino)
+{
+	struct btrfs_key search_key;
+	struct btrfs_path *log_path;
+	int i;
+	int nritems;
+	int ret;
+
+	log_path = btrfs_alloc_path();
+	if (!log_path)
+		return -ENOMEM;
+
+	search_key.objectid = ino;
+	search_key.type = BTRFS_XATTR_ITEM_KEY;
+	search_key.offset = 0;
+again:
+	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+process_leaf:
+	nritems = btrfs_header_nritems(path->nodes[0]);
+	for (i = path->slots[0]; i < nritems; i++) {
+		struct btrfs_key key;
+		struct btrfs_dir_item *di;
+		struct btrfs_dir_item *log_di;
+		u32 total_size;
+		u32 cur;
+
+		btrfs_item_key_to_cpu(path->nodes[0], &key, i);
+		if (key.objectid != ino || key.type != BTRFS_XATTR_ITEM_KEY) {
+			ret = 0;
+			goto out;
+		}
+
+		di = btrfs_item_ptr(path->nodes[0], i, struct btrfs_dir_item);
+		total_size = btrfs_item_size_nr(path->nodes[0], i);
+		cur = 0;
+		while (cur < total_size) {
+			u16 name_len = btrfs_dir_name_len(path->nodes[0], di);
+			u16 data_len = btrfs_dir_data_len(path->nodes[0], di);
+			u32 this_len = sizeof(*di) + name_len + data_len;
+			char *name;
+
+			name = kmalloc(name_len, GFP_NOFS);
+			if (!name) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			read_extent_buffer(path->nodes[0], name,
+					   (unsigned long)(di + 1), name_len);
+
+			log_di = btrfs_lookup_xattr(NULL, log, log_path, ino,
+						    name, name_len, 0);
+			btrfs_release_path(log_path);
+			if (!log_di) {
+				/* Doesn't exist in log tree, so delete it. */
+				btrfs_release_path(path);
+				di = btrfs_lookup_xattr(trans, root, path, ino,
+							name, name_len, -1);
+				kfree(name);
+				if (IS_ERR(di)) {
+					ret = PTR_ERR(di);
+					goto out;
+				}
+				ASSERT(di);
+				ret = btrfs_delete_one_dir_name(trans, root,
+								path, di);
+				if (ret)
+					goto out;
+				btrfs_release_path(path);
+				search_key = key;
+				goto again;
+			}
+			kfree(name);
+			if (IS_ERR(log_di)) {
+				ret = PTR_ERR(log_di);
+				goto out;
+			}
+			cur += this_len;
+			di = (struct btrfs_dir_item *)((char *)di + this_len);
+		}
+	}
+	ret = btrfs_next_leaf(root, path);
+	if (ret > 0)
+		ret = 0;
+	else if (ret == 0)
+		goto process_leaf;
+out:
+	btrfs_free_path(log_path);
+	btrfs_release_path(path);
+	return ret;
+}
+
+
+/*
+ * deletion replay happens before we copy any new directory items
+ * out of the log or out of backreferences from inodes.  It
+ * scans the log to find ranges of keys that log is authoritative for,
+ * and then scans the directory to find items in those ranges that are
+ * not present in the log.
+ *
+ * Anything we don't find in the log is unlinked and removed from the
+ * directory.
+ */
+static noinline int replay_dir_deletes(struct btrfs_trans_handle *trans,
+				       struct btrfs_root *root,
+				       struct btrfs_root *log,
+				       struct btrfs_path *path,
+				       u64 dirid, int del_all)
+{
+	u64 range_start;
+	u64 range_end;
+	int key_type = BTRFS_DIR_LOG_ITEM_KEY;
+	int ret = 0;
+	struct btrfs_key dir_key;
+	struct btrfs_key found_key;
+	struct btrfs_path *log_path;
+	struct inode *dir;
+
+	dir_key.objectid = dirid;
+	dir_key.type = BTRFS_DIR_ITEM_KEY;
+	log_path = btrfs_alloc_path();
+	if (!log_path)
+		return -ENOMEM;
+
+	dir = read_one_inode(root, dirid);
+	/* it isn't an error if the inode isn't there, that can happen
+	 * because we replay the deletes before we copy in the inode item
+	 * from the log
+	 */
+	if (!dir) {
+		btrfs_free_path(log_path);
+		return 0;
+	}
+again:
+	range_start = 0;
+	range_end = 0;
+	while (1) {
+		if (del_all)
+			range_end = (u64)-1;
+		else {
+			ret = find_dir_range(log, path, dirid, key_type,
+					     &range_start, &range_end);
+			if (ret < 0)
+				goto out;
+			else if (ret > 0)
+				break;
+		}
+
+		dir_key.offset = range_start;
+		while (1) {
+			int nritems;
+			ret = btrfs_search_slot(NULL, root, &dir_key, path,
+						0, 0);
+			if (ret < 0)
+				goto out;
+
+			nritems = btrfs_header_nritems(path->nodes[0]);
+			if (path->slots[0] >= nritems) {
+				ret = btrfs_next_leaf(root, path);
+				if (ret == 1)
+					break;
+				else if (ret < 0)
+					goto out;
+			}
+			btrfs_item_key_to_cpu(path->nodes[0], &found_key,
+					      path->slots[0]);
+			if (found_key.objectid != dirid ||
+			    found_key.type != dir_key.type)
+				goto next_type;
+
+			if (found_key.offset > range_end)
+				break;
+
+			ret = check_item_in_log(trans, root, log, path,
+						log_path, dir,
+						&found_key);
+			if (ret)
+				goto out;
+			if (found_key.offset == (u64)-1)
+				break;
+			dir_key.offset = found_key.offset + 1;
+		}
+		btrfs_release_path(path);
+		if (range_end == (u64)-1)
+			break;
+		range_start = range_end + 1;
+	}
+
+next_type:
+	ret = 0;
+	if (key_type == BTRFS_DIR_LOG_ITEM_KEY) {
+		key_type = BTRFS_DIR_LOG_INDEX_KEY;
+		dir_key.type = BTRFS_DIR_INDEX_KEY;
+		btrfs_release_path(path);
+		goto again;
+	}
+out:
+	btrfs_release_path(path);
+	btrfs_free_path(log_path);
+	iput(dir);
+	return ret;
+}
+
+/*
+ * the process_func used to replay items from the log tree.  This
+ * gets called in two different stages.  The first stage just looks
+ * for inodes and makes sure they are all copied into the subvolume.
+ *
+ * The second stage copies all the other item types from the log into
+ * the subvolume.  The two stage approach is slower, but gets rid of
+ * lots of complexity around inodes referencing other inodes that exist
+ * only in the log (references come from either directory items or inode
+ * back refs).
+ */
+static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
+			     struct walk_control *wc, u64 gen, int level)
+{
+	int nritems;
+	struct btrfs_path *path;
+	struct btrfs_root *root = wc->replay_dest;
+	struct btrfs_key key;
+	int i;
+	int ret;
+
+	ret = btrfs_read_buffer(eb, gen, level, NULL);
+	if (ret)
+		return ret;
+
+	level = btrfs_header_level(eb);
+
+	if (level != 0)
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	nritems = btrfs_header_nritems(eb);
+	for (i = 0; i < nritems; i++) {
+		btrfs_item_key_to_cpu(eb, &key, i);
+
+		/* inode keys are done during the first stage */
+		if (key.type == BTRFS_INODE_ITEM_KEY &&
+		    wc->stage == LOG_WALK_REPLAY_INODES) {
+			struct btrfs_inode_item *inode_item;
+			u32 mode;
+
+			inode_item = btrfs_item_ptr(eb, i,
+					    struct btrfs_inode_item);
+			/*
+			 * If we have a tmpfile (O_TMPFILE) that got fsync'ed
+			 * and never got linked before the fsync, skip it, as
+			 * replaying it is pointless since it would be deleted
+			 * later. We skip logging tmpfiles, but it's always
+			 * possible we are replaying a log created with a kernel
+			 * that used to log tmpfiles.
+			 */
+			if (btrfs_inode_nlink(eb, inode_item) == 0) {
+				wc->ignore_cur_inode = true;
+				continue;
+			} else {
+				wc->ignore_cur_inode = false;
+			}
+			ret = replay_xattr_deletes(wc->trans, root, log,
+						   path, key.objectid);
+			if (ret)
+				break;
+			mode = btrfs_inode_mode(eb, inode_item);
+			if (S_ISDIR(mode)) {
+				ret = replay_dir_deletes(wc->trans,
+					 root, log, path, key.objectid, 0);
+				if (ret)
+					break;
+			}
+			ret = overwrite_item(wc->trans, root, path,
+					     eb, i, &key);
+			if (ret)
+				break;
+
+			/*
+			 * Before replaying extents, truncate the inode to its
+			 * size. We need to do it now and not after log replay
+			 * because before an fsync we can have prealloc extents
+			 * added beyond the inode's i_size. If we did it after,
+			 * through orphan cleanup for example, we would drop
+			 * those prealloc extents just after replaying them.
+			 */
+			if (S_ISREG(mode)) {
+				struct inode *inode;
+				u64 from;
+
+				inode = read_one_inode(root, key.objectid);
+				if (!inode) {
+					ret = -EIO;
+					break;
+				}
+				from = ALIGN(i_size_read(inode),
+					     root->fs_info->sectorsize);
+				ret = btrfs_drop_extents(wc->trans, root, inode,
+							 from, (u64)-1, 1);
+				if (!ret) {
+					/* Update the inode's nbytes. */
+					ret = btrfs_update_inode(wc->trans,
+								 root, inode);
+				}
+				iput(inode);
+				if (ret)
+					break;
+			}
+
+			ret = link_to_fixup_dir(wc->trans, root,
+						path, key.objectid);
+			if (ret)
+				break;
+		}
+
+		if (wc->ignore_cur_inode)
+			continue;
+
+		if (key.type == BTRFS_DIR_INDEX_KEY &&
+		    wc->stage == LOG_WALK_REPLAY_DIR_INDEX) {
+			ret = replay_one_dir_item(wc->trans, root, path,
+						  eb, i, &key);
+			if (ret)
+				break;
+		}
+
+		if (wc->stage < LOG_WALK_REPLAY_ALL)
+			continue;
+
+		/* these keys are simply copied */
+		if (key.type == BTRFS_XATTR_ITEM_KEY) {
+			ret = overwrite_item(wc->trans, root, path,
+					     eb, i, &key);
+			if (ret)
+				break;
+		} else if (key.type == BTRFS_INODE_REF_KEY ||
+			   key.type == BTRFS_INODE_EXTREF_KEY) {
+			ret = add_inode_ref(wc->trans, root, log, path,
+					    eb, i, &key);
+			if (ret && ret != -ENOENT)
+				break;
+			ret = 0;
+		} else if (key.type == BTRFS_EXTENT_DATA_KEY) {
+			ret = replay_one_extent(wc->trans, root, path,
+						eb, i, &key);
+			if (ret)
+				break;
+		} else if (key.type == BTRFS_DIR_ITEM_KEY) {
+			ret = replay_one_dir_item(wc->trans, root, path,
+						  eb, i, &key);
+			if (ret)
+				break;
+		}
+	}
+	btrfs_free_path(path);
+	return ret;
+}
+
+static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
+				   struct btrfs_root *root,
+				   struct btrfs_path *path, int *level,
+				   struct walk_control *wc)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	u64 root_owner;
+	u64 bytenr;
+	u64 ptr_gen;
+	struct extent_buffer *next;
+	struct extent_buffer *cur;
+	struct extent_buffer *parent;
+	u32 blocksize;
+	int ret = 0;
+
+	WARN_ON(*level < 0);
+	WARN_ON(*level >= BTRFS_MAX_LEVEL);
+
+	while (*level > 0) {
+		struct btrfs_key first_key;
+
+		WARN_ON(*level < 0);
+		WARN_ON(*level >= BTRFS_MAX_LEVEL);
+		cur = path->nodes[*level];
+
+		WARN_ON(btrfs_header_level(cur) != *level);
+
+		if (path->slots[*level] >=
+		    btrfs_header_nritems(cur))
+			break;
+
+		bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
+		ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
+		btrfs_node_key_to_cpu(cur, &first_key, path->slots[*level]);
+		blocksize = fs_info->nodesize;
+
+		parent = path->nodes[*level];
+		root_owner = btrfs_header_owner(parent);
+
+		next = btrfs_find_create_tree_block(fs_info, bytenr);
+		if (IS_ERR(next))
+			return PTR_ERR(next);
+
+		if (*level == 1) {
+			ret = wc->process_func(root, next, wc, ptr_gen,
+					       *level - 1);
+			if (ret) {
+				free_extent_buffer(next);
+				return ret;
+			}
+
+			path->slots[*level]++;
+			if (wc->free) {
+				ret = btrfs_read_buffer(next, ptr_gen,
+							*level - 1, &first_key);
+				if (ret) {
+					free_extent_buffer(next);
+					return ret;
+				}
+
+				if (trans) {
+					btrfs_tree_lock(next);
+					btrfs_set_lock_blocking(next);
+					clean_tree_block(fs_info, next);
+					btrfs_wait_tree_block_writeback(next);
+					btrfs_tree_unlock(next);
+				} else {
+					if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
+						clear_extent_buffer_dirty(next);
+				}
+
+				WARN_ON(root_owner !=
+					BTRFS_TREE_LOG_OBJECTID);
+				ret = btrfs_free_and_pin_reserved_extent(
+							fs_info, bytenr,
+							blocksize);
+				if (ret) {
+					free_extent_buffer(next);
+					return ret;
+				}
+			}
+			free_extent_buffer(next);
+			continue;
+		}
+		ret = btrfs_read_buffer(next, ptr_gen, *level - 1, &first_key);
+		if (ret) {
+			free_extent_buffer(next);
+			return ret;
+		}
+
+		WARN_ON(*level <= 0);
+		if (path->nodes[*level-1])
+			free_extent_buffer(path->nodes[*level-1]);
+		path->nodes[*level-1] = next;
+		*level = btrfs_header_level(next);
+		path->slots[*level] = 0;
+		cond_resched();
+	}
+	WARN_ON(*level < 0);
+	WARN_ON(*level >= BTRFS_MAX_LEVEL);
+
+	path->slots[*level] = btrfs_header_nritems(path->nodes[*level]);
+
+	cond_resched();
+	return 0;
+}
+
+static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
+				 struct btrfs_root *root,
+				 struct btrfs_path *path, int *level,
+				 struct walk_control *wc)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	u64 root_owner;
+	int i;
+	int slot;
+	int ret;
+
+	for (i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
+		slot = path->slots[i];
+		if (slot + 1 < btrfs_header_nritems(path->nodes[i])) {
+			path->slots[i]++;
+			*level = i;
+			WARN_ON(*level == 0);
+			return 0;
+		} else {
+			struct extent_buffer *parent;
+			if (path->nodes[*level] == root->node)
+				parent = path->nodes[*level];
+			else
+				parent = path->nodes[*level + 1];
+
+			root_owner = btrfs_header_owner(parent);
+			ret = wc->process_func(root, path->nodes[*level], wc,
+				 btrfs_header_generation(path->nodes[*level]),
+				 *level);
+			if (ret)
+				return ret;
+
+			if (wc->free) {
+				struct extent_buffer *next;
+
+				next = path->nodes[*level];
+
+				if (trans) {
+					btrfs_tree_lock(next);
+					btrfs_set_lock_blocking(next);
+					clean_tree_block(fs_info, next);
+					btrfs_wait_tree_block_writeback(next);
+					btrfs_tree_unlock(next);
+				} else {
+					if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
+						clear_extent_buffer_dirty(next);
+				}
+
+				WARN_ON(root_owner != BTRFS_TREE_LOG_OBJECTID);
+				ret = btrfs_free_and_pin_reserved_extent(
+						fs_info,
+						path->nodes[*level]->start,
+						path->nodes[*level]->len);
+				if (ret)
+					return ret;
+			}
+			free_extent_buffer(path->nodes[*level]);
+			path->nodes[*level] = NULL;
+			*level = i + 1;
+		}
+	}
+	return 1;
+}
+
+/*
+ * drop the reference count on the tree rooted at 'snap'.  This traverses
+ * the tree freeing any blocks that have a ref count of zero after being
+ * decremented.
+ */
+static int walk_log_tree(struct btrfs_trans_handle *trans,
+			 struct btrfs_root *log, struct walk_control *wc)
+{
+	struct btrfs_fs_info *fs_info = log->fs_info;
+	int ret = 0;
+	int wret;
+	int level;
+	struct btrfs_path *path;
+	int orig_level;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	level = btrfs_header_level(log->node);
+	orig_level = level;
+	path->nodes[level] = log->node;
+	extent_buffer_get(log->node);
+	path->slots[level] = 0;
+
+	while (1) {
+		wret = walk_down_log_tree(trans, log, path, &level, wc);
+		if (wret > 0)
+			break;
+		if (wret < 0) {
+			ret = wret;
+			goto out;
+		}
+
+		wret = walk_up_log_tree(trans, log, path, &level, wc);
+		if (wret > 0)
+			break;
+		if (wret < 0) {
+			ret = wret;
+			goto out;
+		}
+	}
+
+	/* was the root node processed? if not, catch it here */
+	if (path->nodes[orig_level]) {
+		ret = wc->process_func(log, path->nodes[orig_level], wc,
+			 btrfs_header_generation(path->nodes[orig_level]),
+			 orig_level);
+		if (ret)
+			goto out;
+		if (wc->free) {
+			struct extent_buffer *next;
+
+			next = path->nodes[orig_level];
+
+			if (trans) {
+				btrfs_tree_lock(next);
+				btrfs_set_lock_blocking(next);
+				clean_tree_block(fs_info, next);
+				btrfs_wait_tree_block_writeback(next);
+				btrfs_tree_unlock(next);
+			} else {
+				if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
+					clear_extent_buffer_dirty(next);
+			}
+
+			WARN_ON(log->root_key.objectid !=
+				BTRFS_TREE_LOG_OBJECTID);
+			ret = btrfs_free_and_pin_reserved_extent(fs_info,
+							next->start, next->len);
+			if (ret)
+				goto out;
+		}
+	}
+
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * helper function to update the item for a given subvolumes log root
+ * in the tree of log roots
+ */
+static int update_log_root(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *log,
+			   struct btrfs_root_item *root_item)
+{
+	struct btrfs_fs_info *fs_info = log->fs_info;
+	int ret;
+
+	if (log->log_transid == 1) {
+		/* insert root item on the first sync */
+		ret = btrfs_insert_root(trans, fs_info->log_root_tree,
+				&log->root_key, root_item);
+	} else {
+		ret = btrfs_update_root(trans, fs_info->log_root_tree,
+				&log->root_key, root_item);
+	}
+	return ret;
+}
+
+static void wait_log_commit(struct btrfs_root *root, int transid)
+{
+	DEFINE_WAIT(wait);
+	int index = transid % 2;
+
+	/*
+	 * we only allow two pending log transactions at a time,
+	 * so we know that if ours is more than 2 older than the
+	 * current transaction, we're done
+	 */
+	for (;;) {
+		prepare_to_wait(&root->log_commit_wait[index],
+				&wait, TASK_UNINTERRUPTIBLE);
+
+		if (!(root->log_transid_committed < transid &&
+		      atomic_read(&root->log_commit[index])))
+			break;
+
+		mutex_unlock(&root->log_mutex);
+		schedule();
+		mutex_lock(&root->log_mutex);
+	}
+	finish_wait(&root->log_commit_wait[index], &wait);
+}
+
+static void wait_for_writer(struct btrfs_root *root)
+{
+	DEFINE_WAIT(wait);
+
+	for (;;) {
+		prepare_to_wait(&root->log_writer_wait, &wait,
+				TASK_UNINTERRUPTIBLE);
+		if (!atomic_read(&root->log_writers))
+			break;
+
+		mutex_unlock(&root->log_mutex);
+		schedule();
+		mutex_lock(&root->log_mutex);
+	}
+	finish_wait(&root->log_writer_wait, &wait);
+}
+
+static inline void btrfs_remove_log_ctx(struct btrfs_root *root,
+					struct btrfs_log_ctx *ctx)
+{
+	if (!ctx)
+		return;
+
+	mutex_lock(&root->log_mutex);
+	list_del_init(&ctx->list);
+	mutex_unlock(&root->log_mutex);
+}
+
+/* 
+ * Invoked in log mutex context, or be sure there is no other task which
+ * can access the list.
+ */
+static inline void btrfs_remove_all_log_ctxs(struct btrfs_root *root,
+					     int index, int error)
+{
+	struct btrfs_log_ctx *ctx;
+	struct btrfs_log_ctx *safe;
+
+	list_for_each_entry_safe(ctx, safe, &root->log_ctxs[index], list) {
+		list_del_init(&ctx->list);
+		ctx->log_ret = error;
+	}
+
+	INIT_LIST_HEAD(&root->log_ctxs[index]);
+}
+
+/*
+ * btrfs_sync_log does sends a given tree log down to the disk and
+ * updates the super blocks to record it.  When this call is done,
+ * you know that any inodes previously logged are safely on disk only
+ * if it returns 0.
+ *
+ * Any other return value means you need to call btrfs_commit_transaction.
+ * Some of the edge cases for fsyncing directories that have had unlinks
+ * or renames done in the past mean that sometimes the only safe
+ * fsync is to commit the whole FS.  When btrfs_sync_log returns -EAGAIN,
+ * that has happened.
+ */
+int btrfs_sync_log(struct btrfs_trans_handle *trans,
+		   struct btrfs_root *root, struct btrfs_log_ctx *ctx)
+{
+	int index1;
+	int index2;
+	int mark;
+	int ret;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_root *log = root->log_root;
+	struct btrfs_root *log_root_tree = fs_info->log_root_tree;
+	struct btrfs_root_item new_root_item;
+	int log_transid = 0;
+	struct btrfs_log_ctx root_log_ctx;
+	struct blk_plug plug;
+
+	mutex_lock(&root->log_mutex);
+	log_transid = ctx->log_transid;
+	if (root->log_transid_committed >= log_transid) {
+		mutex_unlock(&root->log_mutex);
+		return ctx->log_ret;
+	}
+
+	index1 = log_transid % 2;
+	if (atomic_read(&root->log_commit[index1])) {
+		wait_log_commit(root, log_transid);
+		mutex_unlock(&root->log_mutex);
+		return ctx->log_ret;
+	}
+	ASSERT(log_transid == root->log_transid);
+	atomic_set(&root->log_commit[index1], 1);
+
+	/* wait for previous tree log sync to complete */
+	if (atomic_read(&root->log_commit[(index1 + 1) % 2]))
+		wait_log_commit(root, log_transid - 1);
+
+	while (1) {
+		int batch = atomic_read(&root->log_batch);
+		/* when we're on an ssd, just kick the log commit out */
+		if (!btrfs_test_opt(fs_info, SSD) &&
+		    test_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state)) {
+			mutex_unlock(&root->log_mutex);
+			schedule_timeout_uninterruptible(1);
+			mutex_lock(&root->log_mutex);
+		}
+		wait_for_writer(root);
+		if (batch == atomic_read(&root->log_batch))
+			break;
+	}
+
+	/* bail out if we need to do a full commit */
+	if (btrfs_need_log_full_commit(fs_info, trans)) {
+		ret = -EAGAIN;
+		mutex_unlock(&root->log_mutex);
+		goto out;
+	}
+
+	if (log_transid % 2 == 0)
+		mark = EXTENT_DIRTY;
+	else
+		mark = EXTENT_NEW;
+
+	/* we start IO on  all the marked extents here, but we don't actually
+	 * wait for them until later.
+	 */
+	blk_start_plug(&plug);
+	ret = btrfs_write_marked_extents(fs_info, &log->dirty_log_pages, mark);
+	if (ret) {
+		blk_finish_plug(&plug);
+		btrfs_abort_transaction(trans, ret);
+		btrfs_set_log_full_commit(fs_info, trans);
+		mutex_unlock(&root->log_mutex);
+		goto out;
+	}
+
+	/*
+	 * We _must_ update under the root->log_mutex in order to make sure we
+	 * have a consistent view of the log root we are trying to commit at
+	 * this moment.
+	 *
+	 * We _must_ copy this into a local copy, because we are not holding the
+	 * log_root_tree->log_mutex yet.  This is important because when we
+	 * commit the log_root_tree we must have a consistent view of the
+	 * log_root_tree when we update the super block to point at the
+	 * log_root_tree bytenr.  If we update the log_root_tree here we'll race
+	 * with the commit and possibly point at the new block which we may not
+	 * have written out.
+	 */
+	btrfs_set_root_node(&log->root_item, log->node);
+	memcpy(&new_root_item, &log->root_item, sizeof(new_root_item));
+
+	root->log_transid++;
+	log->log_transid = root->log_transid;
+	root->log_start_pid = 0;
+	/*
+	 * IO has been started, blocks of the log tree have WRITTEN flag set
+	 * in their headers. new modifications of the log will be written to
+	 * new positions. so it's safe to allow log writers to go in.
+	 */
+	mutex_unlock(&root->log_mutex);
+
+	btrfs_init_log_ctx(&root_log_ctx, NULL);
+
+	mutex_lock(&log_root_tree->log_mutex);
+	atomic_inc(&log_root_tree->log_batch);
+	atomic_inc(&log_root_tree->log_writers);
+
+	index2 = log_root_tree->log_transid % 2;
+	list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]);
+	root_log_ctx.log_transid = log_root_tree->log_transid;
+
+	mutex_unlock(&log_root_tree->log_mutex);
+
+	mutex_lock(&log_root_tree->log_mutex);
+
+	/*
+	 * Now we are safe to update the log_root_tree because we're under the
+	 * log_mutex, and we're a current writer so we're holding the commit
+	 * open until we drop the log_mutex.
+	 */
+	ret = update_log_root(trans, log, &new_root_item);
+
+	if (atomic_dec_and_test(&log_root_tree->log_writers)) {
+		/* atomic_dec_and_test implies a barrier */
+		cond_wake_up_nomb(&log_root_tree->log_writer_wait);
+	}
+
+	if (ret) {
+		if (!list_empty(&root_log_ctx.list))
+			list_del_init(&root_log_ctx.list);
+
+		blk_finish_plug(&plug);
+		btrfs_set_log_full_commit(fs_info, trans);
+
+		if (ret != -ENOSPC) {
+			btrfs_abort_transaction(trans, ret);
+			mutex_unlock(&log_root_tree->log_mutex);
+			goto out;
+		}
+		btrfs_wait_tree_log_extents(log, mark);
+		mutex_unlock(&log_root_tree->log_mutex);
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	if (log_root_tree->log_transid_committed >= root_log_ctx.log_transid) {
+		blk_finish_plug(&plug);
+		list_del_init(&root_log_ctx.list);
+		mutex_unlock(&log_root_tree->log_mutex);
+		ret = root_log_ctx.log_ret;
+		goto out;
+	}
+
+	index2 = root_log_ctx.log_transid % 2;
+	if (atomic_read(&log_root_tree->log_commit[index2])) {
+		blk_finish_plug(&plug);
+		ret = btrfs_wait_tree_log_extents(log, mark);
+		wait_log_commit(log_root_tree,
+				root_log_ctx.log_transid);
+		mutex_unlock(&log_root_tree->log_mutex);
+		if (!ret)
+			ret = root_log_ctx.log_ret;
+		goto out;
+	}
+	ASSERT(root_log_ctx.log_transid == log_root_tree->log_transid);
+	atomic_set(&log_root_tree->log_commit[index2], 1);
+
+	if (atomic_read(&log_root_tree->log_commit[(index2 + 1) % 2])) {
+		wait_log_commit(log_root_tree,
+				root_log_ctx.log_transid - 1);
+	}
+
+	wait_for_writer(log_root_tree);
+
+	/*
+	 * now that we've moved on to the tree of log tree roots,
+	 * check the full commit flag again
+	 */
+	if (btrfs_need_log_full_commit(fs_info, trans)) {
+		blk_finish_plug(&plug);
+		btrfs_wait_tree_log_extents(log, mark);
+		mutex_unlock(&log_root_tree->log_mutex);
+		ret = -EAGAIN;
+		goto out_wake_log_root;
+	}
+
+	ret = btrfs_write_marked_extents(fs_info,
+					 &log_root_tree->dirty_log_pages,
+					 EXTENT_DIRTY | EXTENT_NEW);
+	blk_finish_plug(&plug);
+	if (ret) {
+		btrfs_set_log_full_commit(fs_info, trans);
+		btrfs_abort_transaction(trans, ret);
+		mutex_unlock(&log_root_tree->log_mutex);
+		goto out_wake_log_root;
+	}
+	ret = btrfs_wait_tree_log_extents(log, mark);
+	if (!ret)
+		ret = btrfs_wait_tree_log_extents(log_root_tree,
+						  EXTENT_NEW | EXTENT_DIRTY);
+	if (ret) {
+		btrfs_set_log_full_commit(fs_info, trans);
+		mutex_unlock(&log_root_tree->log_mutex);
+		goto out_wake_log_root;
+	}
+
+	btrfs_set_super_log_root(fs_info->super_for_commit,
+				 log_root_tree->node->start);
+	btrfs_set_super_log_root_level(fs_info->super_for_commit,
+				       btrfs_header_level(log_root_tree->node));
+
+	log_root_tree->log_transid++;
+	mutex_unlock(&log_root_tree->log_mutex);
+
+	/*
+	 * nobody else is going to jump in and write the the ctree
+	 * super here because the log_commit atomic below is protecting
+	 * us.  We must be called with a transaction handle pinning
+	 * the running transaction open, so a full commit can't hop
+	 * in and cause problems either.
+	 */
+	ret = write_all_supers(fs_info, 1);
+	if (ret) {
+		btrfs_set_log_full_commit(fs_info, trans);
+		btrfs_abort_transaction(trans, ret);
+		goto out_wake_log_root;
+	}
+
+	mutex_lock(&root->log_mutex);
+	if (root->last_log_commit < log_transid)
+		root->last_log_commit = log_transid;
+	mutex_unlock(&root->log_mutex);
+
+out_wake_log_root:
+	mutex_lock(&log_root_tree->log_mutex);
+	btrfs_remove_all_log_ctxs(log_root_tree, index2, ret);
+
+	log_root_tree->log_transid_committed++;
+	atomic_set(&log_root_tree->log_commit[index2], 0);
+	mutex_unlock(&log_root_tree->log_mutex);
+
+	/*
+	 * The barrier before waitqueue_active (in cond_wake_up) is needed so
+	 * all the updates above are seen by the woken threads. It might not be
+	 * necessary, but proving that seems to be hard.
+	 */
+	cond_wake_up(&log_root_tree->log_commit_wait[index2]);
+out:
+	mutex_lock(&root->log_mutex);
+	btrfs_remove_all_log_ctxs(root, index1, ret);
+	root->log_transid_committed++;
+	atomic_set(&root->log_commit[index1], 0);
+	mutex_unlock(&root->log_mutex);
+
+	/*
+	 * The barrier before waitqueue_active (in cond_wake_up) is needed so
+	 * all the updates above are seen by the woken threads. It might not be
+	 * necessary, but proving that seems to be hard.
+	 */
+	cond_wake_up(&root->log_commit_wait[index1]);
+	return ret;
+}
+
+static void free_log_tree(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *log)
+{
+	int ret;
+	u64 start;
+	u64 end;
+	struct walk_control wc = {
+		.free = 1,
+		.process_func = process_one_buffer
+	};
+
+	ret = walk_log_tree(trans, log, &wc);
+	if (ret) {
+		if (trans)
+			btrfs_abort_transaction(trans, ret);
+		else
+			btrfs_handle_fs_error(log->fs_info, ret, NULL);
+	}
+
+	while (1) {
+		ret = find_first_extent_bit(&log->dirty_log_pages,
+				0, &start, &end,
+				EXTENT_DIRTY | EXTENT_NEW | EXTENT_NEED_WAIT,
+				NULL);
+		if (ret)
+			break;
+
+		clear_extent_bits(&log->dirty_log_pages, start, end,
+				  EXTENT_DIRTY | EXTENT_NEW | EXTENT_NEED_WAIT);
+	}
+
+	free_extent_buffer(log->node);
+	kfree(log);
+}
+
+/*
+ * free all the extents used by the tree log.  This should be called
+ * at commit time of the full transaction
+ */
+int btrfs_free_log(struct btrfs_trans_handle *trans, struct btrfs_root *root)
+{
+	if (root->log_root) {
+		free_log_tree(trans, root->log_root);
+		root->log_root = NULL;
+	}
+	return 0;
+}
+
+int btrfs_free_log_root_tree(struct btrfs_trans_handle *trans,
+			     struct btrfs_fs_info *fs_info)
+{
+	if (fs_info->log_root_tree) {
+		free_log_tree(trans, fs_info->log_root_tree);
+		fs_info->log_root_tree = NULL;
+	}
+	return 0;
+}
+
+/*
+ * Check if an inode was logged in the current transaction. We can't always rely
+ * on an inode's logged_trans value, because it's an in-memory only field and
+ * therefore not persisted. This means that its value is lost if the inode gets
+ * evicted and loaded again from disk (in which case it has a value of 0, and
+ * certainly it is smaller then any possible transaction ID), when that happens
+ * the full_sync flag is set in the inode's runtime flags, so on that case we
+ * assume eviction happened and ignore the logged_trans value, assuming the
+ * worst case, that the inode was logged before in the current transaction.
+ */
+static bool inode_logged(struct btrfs_trans_handle *trans,
+			 struct btrfs_inode *inode)
+{
+	if (inode->logged_trans == trans->transid)
+		return true;
+
+	if (inode->last_trans == trans->transid &&
+	    test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags) &&
+	    !test_bit(BTRFS_FS_LOG_RECOVERING, &trans->fs_info->flags))
+		return true;
+
+	return false;
+}
+
+/*
+ * If both a file and directory are logged, and unlinks or renames are
+ * mixed in, we have a few interesting corners:
+ *
+ * create file X in dir Y
+ * link file X to X.link in dir Y
+ * fsync file X
+ * unlink file X but leave X.link
+ * fsync dir Y
+ *
+ * After a crash we would expect only X.link to exist.  But file X
+ * didn't get fsync'd again so the log has back refs for X and X.link.
+ *
+ * We solve this by removing directory entries and inode backrefs from the
+ * log when a file that was logged in the current transaction is
+ * unlinked.  Any later fsync will include the updated log entries, and
+ * we'll be able to reconstruct the proper directory items from backrefs.
+ *
+ * This optimizations allows us to avoid relogging the entire inode
+ * or the entire directory.
+ */
+int btrfs_del_dir_entries_in_log(struct btrfs_trans_handle *trans,
+				 struct btrfs_root *root,
+				 const char *name, int name_len,
+				 struct btrfs_inode *dir, u64 index)
+{
+	struct btrfs_root *log;
+	struct btrfs_dir_item *di;
+	struct btrfs_path *path;
+	int ret;
+	int err = 0;
+	int bytes_del = 0;
+	u64 dir_ino = btrfs_ino(dir);
+
+	if (!inode_logged(trans, dir))
+		return 0;
+
+	ret = join_running_log_trans(root);
+	if (ret)
+		return 0;
+
+	mutex_lock(&dir->log_mutex);
+
+	log = root->log_root;
+	path = btrfs_alloc_path();
+	if (!path) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+
+	di = btrfs_lookup_dir_item(trans, log, path, dir_ino,
+				   name, name_len, -1);
+	if (IS_ERR(di)) {
+		err = PTR_ERR(di);
+		goto fail;
+	}
+	if (di) {
+		ret = btrfs_delete_one_dir_name(trans, log, path, di);
+		bytes_del += name_len;
+		if (ret) {
+			err = ret;
+			goto fail;
+		}
+	}
+	btrfs_release_path(path);
+	di = btrfs_lookup_dir_index_item(trans, log, path, dir_ino,
+					 index, name, name_len, -1);
+	if (IS_ERR(di)) {
+		err = PTR_ERR(di);
+		goto fail;
+	}
+	if (di) {
+		ret = btrfs_delete_one_dir_name(trans, log, path, di);
+		bytes_del += name_len;
+		if (ret) {
+			err = ret;
+			goto fail;
+		}
+	}
+
+	/* update the directory size in the log to reflect the names
+	 * we have removed
+	 */
+	if (bytes_del) {
+		struct btrfs_key key;
+
+		key.objectid = dir_ino;
+		key.offset = 0;
+		key.type = BTRFS_INODE_ITEM_KEY;
+		btrfs_release_path(path);
+
+		ret = btrfs_search_slot(trans, log, &key, path, 0, 1);
+		if (ret < 0) {
+			err = ret;
+			goto fail;
+		}
+		if (ret == 0) {
+			struct btrfs_inode_item *item;
+			u64 i_size;
+
+			item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+					      struct btrfs_inode_item);
+			i_size = btrfs_inode_size(path->nodes[0], item);
+			if (i_size > bytes_del)
+				i_size -= bytes_del;
+			else
+				i_size = 0;
+			btrfs_set_inode_size(path->nodes[0], item, i_size);
+			btrfs_mark_buffer_dirty(path->nodes[0]);
+		} else
+			ret = 0;
+		btrfs_release_path(path);
+	}
+fail:
+	btrfs_free_path(path);
+out_unlock:
+	mutex_unlock(&dir->log_mutex);
+	if (err == -ENOSPC) {
+		btrfs_set_log_full_commit(root->fs_info, trans);
+		err = 0;
+	} else if (err < 0 && err != -ENOENT) {
+		/* ENOENT can be returned if the entry hasn't been fsynced yet */
+		btrfs_abort_transaction(trans, err);
+	}
+
+	btrfs_end_log_trans(root);
+
+	return err;
+}
+
+/* see comments for btrfs_del_dir_entries_in_log */
+int btrfs_del_inode_ref_in_log(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *root,
+			       const char *name, int name_len,
+			       struct btrfs_inode *inode, u64 dirid)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_root *log;
+	u64 index;
+	int ret;
+
+	if (!inode_logged(trans, inode))
+		return 0;
+
+	ret = join_running_log_trans(root);
+	if (ret)
+		return 0;
+	log = root->log_root;
+	mutex_lock(&inode->log_mutex);
+
+	ret = btrfs_del_inode_ref(trans, log, name, name_len, btrfs_ino(inode),
+				  dirid, &index);
+	mutex_unlock(&inode->log_mutex);
+	if (ret == -ENOSPC) {
+		btrfs_set_log_full_commit(fs_info, trans);
+		ret = 0;
+	} else if (ret < 0 && ret != -ENOENT)
+		btrfs_abort_transaction(trans, ret);
+	btrfs_end_log_trans(root);
+
+	return ret;
+}
+
+/*
+ * creates a range item in the log for 'dirid'.  first_offset and
+ * last_offset tell us which parts of the key space the log should
+ * be considered authoritative for.
+ */
+static noinline int insert_dir_log_key(struct btrfs_trans_handle *trans,
+				       struct btrfs_root *log,
+				       struct btrfs_path *path,
+				       int key_type, u64 dirid,
+				       u64 first_offset, u64 last_offset)
+{
+	int ret;
+	struct btrfs_key key;
+	struct btrfs_dir_log_item *item;
+
+	key.objectid = dirid;
+	key.offset = first_offset;
+	if (key_type == BTRFS_DIR_ITEM_KEY)
+		key.type = BTRFS_DIR_LOG_ITEM_KEY;
+	else
+		key.type = BTRFS_DIR_LOG_INDEX_KEY;
+	ret = btrfs_insert_empty_item(trans, log, path, &key, sizeof(*item));
+	if (ret)
+		return ret;
+
+	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			      struct btrfs_dir_log_item);
+	btrfs_set_dir_log_end(path->nodes[0], item, last_offset);
+	btrfs_mark_buffer_dirty(path->nodes[0]);
+	btrfs_release_path(path);
+	return 0;
+}
+
+/*
+ * log all the items included in the current transaction for a given
+ * directory.  This also creates the range items in the log tree required
+ * to replay anything deleted before the fsync
+ */
+static noinline int log_dir_items(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root, struct btrfs_inode *inode,
+			  struct btrfs_path *path,
+			  struct btrfs_path *dst_path, int key_type,
+			  struct btrfs_log_ctx *ctx,
+			  u64 min_offset, u64 *last_offset_ret)
+{
+	struct btrfs_key min_key;
+	struct btrfs_root *log = root->log_root;
+	struct extent_buffer *src;
+	int err = 0;
+	int ret;
+	int i;
+	int nritems;
+	u64 first_offset = min_offset;
+	u64 last_offset = (u64)-1;
+	u64 ino = btrfs_ino(inode);
+
+	log = root->log_root;
+
+	min_key.objectid = ino;
+	min_key.type = key_type;
+	min_key.offset = min_offset;
+
+	ret = btrfs_search_forward(root, &min_key, path, trans->transid);
+
+	/*
+	 * we didn't find anything from this transaction, see if there
+	 * is anything at all
+	 */
+	if (ret != 0 || min_key.objectid != ino || min_key.type != key_type) {
+		min_key.objectid = ino;
+		min_key.type = key_type;
+		min_key.offset = (u64)-1;
+		btrfs_release_path(path);
+		ret = btrfs_search_slot(NULL, root, &min_key, path, 0, 0);
+		if (ret < 0) {
+			btrfs_release_path(path);
+			return ret;
+		}
+		ret = btrfs_previous_item(root, path, ino, key_type);
+
+		/* if ret == 0 there are items for this type,
+		 * create a range to tell us the last key of this type.
+		 * otherwise, there are no items in this directory after
+		 * *min_offset, and we create a range to indicate that.
+		 */
+		if (ret == 0) {
+			struct btrfs_key tmp;
+			btrfs_item_key_to_cpu(path->nodes[0], &tmp,
+					      path->slots[0]);
+			if (key_type == tmp.type)
+				first_offset = max(min_offset, tmp.offset) + 1;
+		}
+		goto done;
+	}
+
+	/* go backward to find any previous key */
+	ret = btrfs_previous_item(root, path, ino, key_type);
+	if (ret == 0) {
+		struct btrfs_key tmp;
+		btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]);
+		if (key_type == tmp.type) {
+			first_offset = tmp.offset;
+			ret = overwrite_item(trans, log, dst_path,
+					     path->nodes[0], path->slots[0],
+					     &tmp);
+			if (ret) {
+				err = ret;
+				goto done;
+			}
+		}
+	}
+	btrfs_release_path(path);
+
+	/*
+	 * Find the first key from this transaction again.  See the note for
+	 * log_new_dir_dentries, if we're logging a directory recursively we
+	 * won't be holding its i_mutex, which means we can modify the directory
+	 * while we're logging it.  If we remove an entry between our first
+	 * search and this search we'll not find the key again and can just
+	 * bail.
+	 */
+search:
+	ret = btrfs_search_slot(NULL, root, &min_key, path, 0, 0);
+	if (ret != 0)
+		goto done;
+
+	/*
+	 * we have a block from this transaction, log every item in it
+	 * from our directory
+	 */
+	while (1) {
+		struct btrfs_key tmp;
+		src = path->nodes[0];
+		nritems = btrfs_header_nritems(src);
+		for (i = path->slots[0]; i < nritems; i++) {
+			struct btrfs_dir_item *di;
+
+			btrfs_item_key_to_cpu(src, &min_key, i);
+
+			if (min_key.objectid != ino || min_key.type != key_type)
+				goto done;
+
+			if (need_resched()) {
+				btrfs_release_path(path);
+				cond_resched();
+				goto search;
+			}
+
+			ret = overwrite_item(trans, log, dst_path, src, i,
+					     &min_key);
+			if (ret) {
+				err = ret;
+				goto done;
+			}
+
+			/*
+			 * We must make sure that when we log a directory entry,
+			 * the corresponding inode, after log replay, has a
+			 * matching link count. For example:
+			 *
+			 * touch foo
+			 * mkdir mydir
+			 * sync
+			 * ln foo mydir/bar
+			 * xfs_io -c "fsync" mydir
+			 * <crash>
+			 * <mount fs and log replay>
+			 *
+			 * Would result in a fsync log that when replayed, our
+			 * file inode would have a link count of 1, but we get
+			 * two directory entries pointing to the same inode.
+			 * After removing one of the names, it would not be
+			 * possible to remove the other name, which resulted
+			 * always in stale file handle errors, and would not
+			 * be possible to rmdir the parent directory, since
+			 * its i_size could never decrement to the value
+			 * BTRFS_EMPTY_DIR_SIZE, resulting in -ENOTEMPTY errors.
+			 */
+			di = btrfs_item_ptr(src, i, struct btrfs_dir_item);
+			btrfs_dir_item_key_to_cpu(src, di, &tmp);
+			if (ctx &&
+			    (btrfs_dir_transid(src, di) == trans->transid ||
+			     btrfs_dir_type(src, di) == BTRFS_FT_DIR) &&
+			    tmp.type != BTRFS_ROOT_ITEM_KEY)
+				ctx->log_new_dentries = true;
+		}
+		path->slots[0] = nritems;
+
+		/*
+		 * look ahead to the next item and see if it is also
+		 * from this directory and from this transaction
+		 */
+		ret = btrfs_next_leaf(root, path);
+		if (ret) {
+			if (ret == 1)
+				last_offset = (u64)-1;
+			else
+				err = ret;
+			goto done;
+		}
+		btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]);
+		if (tmp.objectid != ino || tmp.type != key_type) {
+			last_offset = (u64)-1;
+			goto done;
+		}
+		if (btrfs_header_generation(path->nodes[0]) != trans->transid) {
+			ret = overwrite_item(trans, log, dst_path,
+					     path->nodes[0], path->slots[0],
+					     &tmp);
+			if (ret)
+				err = ret;
+			else
+				last_offset = tmp.offset;
+			goto done;
+		}
+	}
+done:
+	btrfs_release_path(path);
+	btrfs_release_path(dst_path);
+
+	if (err == 0) {
+		*last_offset_ret = last_offset;
+		/*
+		 * insert the log range keys to indicate where the log
+		 * is valid
+		 */
+		ret = insert_dir_log_key(trans, log, path, key_type,
+					 ino, first_offset, last_offset);
+		if (ret)
+			err = ret;
+	}
+	return err;
+}
+
+/*
+ * logging directories is very similar to logging inodes, We find all the items
+ * from the current transaction and write them to the log.
+ *
+ * The recovery code scans the directory in the subvolume, and if it finds a
+ * key in the range logged that is not present in the log tree, then it means
+ * that dir entry was unlinked during the transaction.
+ *
+ * In order for that scan to work, we must include one key smaller than
+ * the smallest logged by this transaction and one key larger than the largest
+ * key logged by this transaction.
+ */
+static noinline int log_directory_changes(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root, struct btrfs_inode *inode,
+			  struct btrfs_path *path,
+			  struct btrfs_path *dst_path,
+			  struct btrfs_log_ctx *ctx)
+{
+	u64 min_key;
+	u64 max_key;
+	int ret;
+	int key_type = BTRFS_DIR_ITEM_KEY;
+
+again:
+	min_key = 0;
+	max_key = 0;
+	while (1) {
+		ret = log_dir_items(trans, root, inode, path, dst_path, key_type,
+				ctx, min_key, &max_key);
+		if (ret)
+			return ret;
+		if (max_key == (u64)-1)
+			break;
+		min_key = max_key + 1;
+	}
+
+	if (key_type == BTRFS_DIR_ITEM_KEY) {
+		key_type = BTRFS_DIR_INDEX_KEY;
+		goto again;
+	}
+	return 0;
+}
+
+/*
+ * a helper function to drop items from the log before we relog an
+ * inode.  max_key_type indicates the highest item type to remove.
+ * This cannot be run for file data extents because it does not
+ * free the extents they point to.
+ */
+static int drop_objectid_items(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *log,
+				  struct btrfs_path *path,
+				  u64 objectid, int max_key_type)
+{
+	int ret;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	int start_slot;
+
+	key.objectid = objectid;
+	key.type = max_key_type;
+	key.offset = (u64)-1;
+
+	while (1) {
+		ret = btrfs_search_slot(trans, log, &key, path, -1, 1);
+		BUG_ON(ret == 0); /* Logic error */
+		if (ret < 0)
+			break;
+
+		if (path->slots[0] == 0)
+			break;
+
+		path->slots[0]--;
+		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
+				      path->slots[0]);
+
+		if (found_key.objectid != objectid)
+			break;
+
+		found_key.offset = 0;
+		found_key.type = 0;
+		ret = btrfs_bin_search(path->nodes[0], &found_key, 0,
+				       &start_slot);
+
+		ret = btrfs_del_items(trans, log, path, start_slot,
+				      path->slots[0] - start_slot + 1);
+		/*
+		 * If start slot isn't 0 then we don't need to re-search, we've
+		 * found the last guy with the objectid in this tree.
+		 */
+		if (ret || start_slot != 0)
+			break;
+		btrfs_release_path(path);
+	}
+	btrfs_release_path(path);
+	if (ret > 0)
+		ret = 0;
+	return ret;
+}
+
+static void fill_inode_item(struct btrfs_trans_handle *trans,
+			    struct extent_buffer *leaf,
+			    struct btrfs_inode_item *item,
+			    struct inode *inode, int log_inode_only,
+			    u64 logged_isize)
+{
+	struct btrfs_map_token token;
+
+	btrfs_init_map_token(&token);
+
+	if (log_inode_only) {
+		/* set the generation to zero so the recover code
+		 * can tell the difference between an logging
+		 * just to say 'this inode exists' and a logging
+		 * to say 'update this inode with these values'
+		 */
+		btrfs_set_token_inode_generation(leaf, item, 0, &token);
+		btrfs_set_token_inode_size(leaf, item, logged_isize, &token);
+	} else {
+		btrfs_set_token_inode_generation(leaf, item,
+						 BTRFS_I(inode)->generation,
+						 &token);
+		btrfs_set_token_inode_size(leaf, item, inode->i_size, &token);
+	}
+
+	btrfs_set_token_inode_uid(leaf, item, i_uid_read(inode), &token);
+	btrfs_set_token_inode_gid(leaf, item, i_gid_read(inode), &token);
+	btrfs_set_token_inode_mode(leaf, item, inode->i_mode, &token);
+	btrfs_set_token_inode_nlink(leaf, item, inode->i_nlink, &token);
+
+	btrfs_set_token_timespec_sec(leaf, &item->atime,
+				     inode->i_atime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->atime,
+				      inode->i_atime.tv_nsec, &token);
+
+	btrfs_set_token_timespec_sec(leaf, &item->mtime,
+				     inode->i_mtime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->mtime,
+				      inode->i_mtime.tv_nsec, &token);
+
+	btrfs_set_token_timespec_sec(leaf, &item->ctime,
+				     inode->i_ctime.tv_sec, &token);
+	btrfs_set_token_timespec_nsec(leaf, &item->ctime,
+				      inode->i_ctime.tv_nsec, &token);
+
+	btrfs_set_token_inode_nbytes(leaf, item, inode_get_bytes(inode),
+				     &token);
+
+	btrfs_set_token_inode_sequence(leaf, item,
+				       inode_peek_iversion(inode), &token);
+	btrfs_set_token_inode_transid(leaf, item, trans->transid, &token);
+	btrfs_set_token_inode_rdev(leaf, item, inode->i_rdev, &token);
+	btrfs_set_token_inode_flags(leaf, item, BTRFS_I(inode)->flags, &token);
+	btrfs_set_token_inode_block_group(leaf, item, 0, &token);
+}
+
+static int log_inode_item(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *log, struct btrfs_path *path,
+			  struct btrfs_inode *inode)
+{
+	struct btrfs_inode_item *inode_item;
+	int ret;
+
+	ret = btrfs_insert_empty_item(trans, log, path,
+				      &inode->location, sizeof(*inode_item));
+	if (ret && ret != -EEXIST)
+		return ret;
+	inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				    struct btrfs_inode_item);
+	fill_inode_item(trans, path->nodes[0], inode_item, &inode->vfs_inode,
+			0, 0);
+	btrfs_release_path(path);
+	return 0;
+}
+
+static int log_csums(struct btrfs_trans_handle *trans,
+		     struct btrfs_root *log_root,
+		     struct btrfs_ordered_sum *sums)
+{
+	int ret;
+
+	/*
+	 * Due to extent cloning, we might have logged a csum item that covers a
+	 * subrange of a cloned extent, and later we can end up logging a csum
+	 * item for a larger subrange of the same extent or the entire range.
+	 * This would leave csum items in the log tree that cover the same range
+	 * and break the searches for checksums in the log tree, resulting in
+	 * some checksums missing in the fs/subvolume tree. So just delete (or
+	 * trim and adjust) any existing csum items in the log for this range.
+	 */
+	ret = btrfs_del_csums(trans, log_root, sums->bytenr, sums->len);
+	if (ret)
+		return ret;
+
+	return btrfs_csum_file_blocks(trans, log_root, sums);
+}
+
+static noinline int copy_items(struct btrfs_trans_handle *trans,
+			       struct btrfs_inode *inode,
+			       struct btrfs_path *dst_path,
+			       struct btrfs_path *src_path,
+			       int start_slot, int nr, int inode_only,
+			       u64 logged_isize)
+{
+	struct btrfs_fs_info *fs_info = trans->fs_info;
+	unsigned long src_offset;
+	unsigned long dst_offset;
+	struct btrfs_root *log = inode->root->log_root;
+	struct btrfs_file_extent_item *extent;
+	struct btrfs_inode_item *inode_item;
+	struct extent_buffer *src = src_path->nodes[0];
+	int ret;
+	struct btrfs_key *ins_keys;
+	u32 *ins_sizes;
+	char *ins_data;
+	int i;
+	struct list_head ordered_sums;
+	int skip_csum = inode->flags & BTRFS_INODE_NODATASUM;
+
+	INIT_LIST_HEAD(&ordered_sums);
+
+	ins_data = kmalloc(nr * sizeof(struct btrfs_key) +
+			   nr * sizeof(u32), GFP_NOFS);
+	if (!ins_data)
+		return -ENOMEM;
+
+	ins_sizes = (u32 *)ins_data;
+	ins_keys = (struct btrfs_key *)(ins_data + nr * sizeof(u32));
+
+	for (i = 0; i < nr; i++) {
+		ins_sizes[i] = btrfs_item_size_nr(src, i + start_slot);
+		btrfs_item_key_to_cpu(src, ins_keys + i, i + start_slot);
+	}
+	ret = btrfs_insert_empty_items(trans, log, dst_path,
+				       ins_keys, ins_sizes, nr);
+	if (ret) {
+		kfree(ins_data);
+		return ret;
+	}
+
+	for (i = 0; i < nr; i++, dst_path->slots[0]++) {
+		dst_offset = btrfs_item_ptr_offset(dst_path->nodes[0],
+						   dst_path->slots[0]);
+
+		src_offset = btrfs_item_ptr_offset(src, start_slot + i);
+
+		if (ins_keys[i].type == BTRFS_INODE_ITEM_KEY) {
+			inode_item = btrfs_item_ptr(dst_path->nodes[0],
+						    dst_path->slots[0],
+						    struct btrfs_inode_item);
+			fill_inode_item(trans, dst_path->nodes[0], inode_item,
+					&inode->vfs_inode,
+					inode_only == LOG_INODE_EXISTS,
+					logged_isize);
+		} else {
+			copy_extent_buffer(dst_path->nodes[0], src, dst_offset,
+					   src_offset, ins_sizes[i]);
+		}
+
+		/* take a reference on file data extents so that truncates
+		 * or deletes of this inode don't have to relog the inode
+		 * again
+		 */
+		if (ins_keys[i].type == BTRFS_EXTENT_DATA_KEY &&
+		    !skip_csum) {
+			int found_type;
+			extent = btrfs_item_ptr(src, start_slot + i,
+						struct btrfs_file_extent_item);
+
+			if (btrfs_file_extent_generation(src, extent) < trans->transid)
+				continue;
+
+			found_type = btrfs_file_extent_type(src, extent);
+			if (found_type == BTRFS_FILE_EXTENT_REG) {
+				u64 ds, dl, cs, cl;
+				ds = btrfs_file_extent_disk_bytenr(src,
+								extent);
+				/* ds == 0 is a hole */
+				if (ds == 0)
+					continue;
+
+				dl = btrfs_file_extent_disk_num_bytes(src,
+								extent);
+				cs = btrfs_file_extent_offset(src, extent);
+				cl = btrfs_file_extent_num_bytes(src,
+								extent);
+				if (btrfs_file_extent_compression(src,
+								  extent)) {
+					cs = 0;
+					cl = dl;
+				}
+
+				ret = btrfs_lookup_csums_range(
+						fs_info->csum_root,
+						ds + cs, ds + cs + cl - 1,
+						&ordered_sums, 0);
+				if (ret)
+					break;
+			}
+		}
+	}
+
+	btrfs_mark_buffer_dirty(dst_path->nodes[0]);
+	btrfs_release_path(dst_path);
+	kfree(ins_data);
+
+	/*
+	 * we have to do this after the loop above to avoid changing the
+	 * log tree while trying to change the log tree.
+	 */
+	while (!list_empty(&ordered_sums)) {
+		struct btrfs_ordered_sum *sums = list_entry(ordered_sums.next,
+						   struct btrfs_ordered_sum,
+						   list);
+		if (!ret)
+			ret = log_csums(trans, log, sums);
+		list_del(&sums->list);
+		kfree(sums);
+	}
+
+	return ret;
+}
+
+static int extent_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+	struct extent_map *em1, *em2;
+
+	em1 = list_entry(a, struct extent_map, list);
+	em2 = list_entry(b, struct extent_map, list);
+
+	if (em1->start < em2->start)
+		return -1;
+	else if (em1->start > em2->start)
+		return 1;
+	return 0;
+}
+
+static int log_extent_csums(struct btrfs_trans_handle *trans,
+			    struct btrfs_inode *inode,
+			    struct btrfs_root *log_root,
+			    const struct extent_map *em)
+{
+	u64 csum_offset;
+	u64 csum_len;
+	LIST_HEAD(ordered_sums);
+	int ret = 0;
+
+	if (inode->flags & BTRFS_INODE_NODATASUM ||
+	    test_bit(EXTENT_FLAG_PREALLOC, &em->flags) ||
+	    em->block_start == EXTENT_MAP_HOLE)
+		return 0;
+
+	/* If we're compressed we have to save the entire range of csums. */
+	if (em->compress_type) {
+		csum_offset = 0;
+		csum_len = max(em->block_len, em->orig_block_len);
+	} else {
+		csum_offset = em->mod_start - em->start;
+		csum_len = em->mod_len;
+	}
+
+	/* block start is already adjusted for the file extent offset. */
+	ret = btrfs_lookup_csums_range(trans->fs_info->csum_root,
+				       em->block_start + csum_offset,
+				       em->block_start + csum_offset +
+				       csum_len - 1, &ordered_sums, 0);
+	if (ret)
+		return ret;
+
+	while (!list_empty(&ordered_sums)) {
+		struct btrfs_ordered_sum *sums = list_entry(ordered_sums.next,
+						   struct btrfs_ordered_sum,
+						   list);
+		if (!ret)
+			ret = log_csums(trans, log_root, sums);
+		list_del(&sums->list);
+		kfree(sums);
+	}
+
+	return ret;
+}
+
+static int log_one_extent(struct btrfs_trans_handle *trans,
+			  struct btrfs_inode *inode, struct btrfs_root *root,
+			  const struct extent_map *em,
+			  struct btrfs_path *path,
+			  struct btrfs_log_ctx *ctx)
+{
+	struct btrfs_root *log = root->log_root;
+	struct btrfs_file_extent_item *fi;
+	struct extent_buffer *leaf;
+	struct btrfs_map_token token;
+	struct btrfs_key key;
+	u64 extent_offset = em->start - em->orig_start;
+	u64 block_len;
+	int ret;
+	int extent_inserted = 0;
+
+	ret = log_extent_csums(trans, inode, log, em);
+	if (ret)
+		return ret;
+
+	btrfs_init_map_token(&token);
+
+	ret = __btrfs_drop_extents(trans, log, &inode->vfs_inode, path, em->start,
+				   em->start + em->len, NULL, 0, 1,
+				   sizeof(*fi), &extent_inserted);
+	if (ret)
+		return ret;
+
+	if (!extent_inserted) {
+		key.objectid = btrfs_ino(inode);
+		key.type = BTRFS_EXTENT_DATA_KEY;
+		key.offset = em->start;
+
+		ret = btrfs_insert_empty_item(trans, log, path, &key,
+					      sizeof(*fi));
+		if (ret)
+			return ret;
+	}
+	leaf = path->nodes[0];
+	fi = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+
+	btrfs_set_token_file_extent_generation(leaf, fi, trans->transid,
+					       &token);
+	if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+		btrfs_set_token_file_extent_type(leaf, fi,
+						 BTRFS_FILE_EXTENT_PREALLOC,
+						 &token);
+	else
+		btrfs_set_token_file_extent_type(leaf, fi,
+						 BTRFS_FILE_EXTENT_REG,
+						 &token);
+
+	block_len = max(em->block_len, em->orig_block_len);
+	if (em->compress_type != BTRFS_COMPRESS_NONE) {
+		btrfs_set_token_file_extent_disk_bytenr(leaf, fi,
+							em->block_start,
+							&token);
+		btrfs_set_token_file_extent_disk_num_bytes(leaf, fi, block_len,
+							   &token);
+	} else if (em->block_start < EXTENT_MAP_LAST_BYTE) {
+		btrfs_set_token_file_extent_disk_bytenr(leaf, fi,
+							em->block_start -
+							extent_offset, &token);
+		btrfs_set_token_file_extent_disk_num_bytes(leaf, fi, block_len,
+							   &token);
+	} else {
+		btrfs_set_token_file_extent_disk_bytenr(leaf, fi, 0, &token);
+		btrfs_set_token_file_extent_disk_num_bytes(leaf, fi, 0,
+							   &token);
+	}
+
+	btrfs_set_token_file_extent_offset(leaf, fi, extent_offset, &token);
+	btrfs_set_token_file_extent_num_bytes(leaf, fi, em->len, &token);
+	btrfs_set_token_file_extent_ram_bytes(leaf, fi, em->ram_bytes, &token);
+	btrfs_set_token_file_extent_compression(leaf, fi, em->compress_type,
+						&token);
+	btrfs_set_token_file_extent_encryption(leaf, fi, 0, &token);
+	btrfs_set_token_file_extent_other_encoding(leaf, fi, 0, &token);
+	btrfs_mark_buffer_dirty(leaf);
+
+	btrfs_release_path(path);
+
+	return ret;
+}
+
+/*
+ * Log all prealloc extents beyond the inode's i_size to make sure we do not
+ * lose them after doing a fast fsync and replaying the log. We scan the
+ * subvolume's root instead of iterating the inode's extent map tree because
+ * otherwise we can log incorrect extent items based on extent map conversion.
+ * That can happen due to the fact that extent maps are merged when they
+ * are not in the extent map tree's list of modified extents.
+ */
+static int btrfs_log_prealloc_extents(struct btrfs_trans_handle *trans,
+				      struct btrfs_inode *inode,
+				      struct btrfs_path *path)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_key key;
+	const u64 i_size = i_size_read(&inode->vfs_inode);
+	const u64 ino = btrfs_ino(inode);
+	struct btrfs_path *dst_path = NULL;
+	bool dropped_extents = false;
+	u64 truncate_offset = i_size;
+	struct extent_buffer *leaf;
+	int slot;
+	int ins_nr = 0;
+	int start_slot;
+	int ret;
+
+	if (!(inode->flags & BTRFS_INODE_PREALLOC))
+		return 0;
+
+	key.objectid = ino;
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = i_size;
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+
+	/*
+	 * We must check if there is a prealloc extent that starts before the
+	 * i_size and crosses the i_size boundary. This is to ensure later we
+	 * truncate down to the end of that extent and not to the i_size, as
+	 * otherwise we end up losing part of the prealloc extent after a log
+	 * replay and with an implicit hole if there is another prealloc extent
+	 * that starts at an offset beyond i_size.
+	 */
+	ret = btrfs_previous_item(root, path, ino, BTRFS_EXTENT_DATA_KEY);
+	if (ret < 0)
+		goto out;
+
+	if (ret == 0) {
+		struct btrfs_file_extent_item *ei;
+
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+		ei = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+
+		if (btrfs_file_extent_type(leaf, ei) ==
+		    BTRFS_FILE_EXTENT_PREALLOC) {
+			u64 extent_end;
+
+			btrfs_item_key_to_cpu(leaf, &key, slot);
+			extent_end = key.offset +
+				btrfs_file_extent_num_bytes(leaf, ei);
+
+			if (extent_end > i_size)
+				truncate_offset = extent_end;
+		}
+	} else {
+		ret = 0;
+	}
+
+	while (true) {
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+
+		if (slot >= btrfs_header_nritems(leaf)) {
+			if (ins_nr > 0) {
+				ret = copy_items(trans, inode, dst_path, path,
+						 start_slot, ins_nr, 1, 0);
+				if (ret < 0)
+					goto out;
+				ins_nr = 0;
+			}
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			if (ret > 0) {
+				ret = 0;
+				break;
+			}
+			continue;
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (key.objectid > ino)
+			break;
+		if (WARN_ON_ONCE(key.objectid < ino) ||
+		    key.type < BTRFS_EXTENT_DATA_KEY ||
+		    key.offset < i_size) {
+			path->slots[0]++;
+			continue;
+		}
+		if (!dropped_extents) {
+			/*
+			 * Avoid logging extent items logged in past fsync calls
+			 * and leading to duplicate keys in the log tree.
+			 */
+			do {
+				ret = btrfs_truncate_inode_items(trans,
+							 root->log_root,
+							 &inode->vfs_inode,
+							 truncate_offset,
+							 BTRFS_EXTENT_DATA_KEY);
+			} while (ret == -EAGAIN);
+			if (ret)
+				goto out;
+			dropped_extents = true;
+		}
+		if (ins_nr == 0)
+			start_slot = slot;
+		ins_nr++;
+		path->slots[0]++;
+		if (!dst_path) {
+			dst_path = btrfs_alloc_path();
+			if (!dst_path) {
+				ret = -ENOMEM;
+				goto out;
+			}
+		}
+	}
+	if (ins_nr > 0) {
+		ret = copy_items(trans, inode, dst_path, path,
+				 start_slot, ins_nr, 1, 0);
+		if (ret > 0)
+			ret = 0;
+	}
+out:
+	btrfs_release_path(path);
+	btrfs_free_path(dst_path);
+	return ret;
+}
+
+static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
+				     struct btrfs_root *root,
+				     struct btrfs_inode *inode,
+				     struct btrfs_path *path,
+				     struct btrfs_log_ctx *ctx,
+				     const u64 start,
+				     const u64 end)
+{
+	struct extent_map *em, *n;
+	struct list_head extents;
+	struct extent_map_tree *tree = &inode->extent_tree;
+	u64 logged_start, logged_end;
+	u64 test_gen;
+	int ret = 0;
+	int num = 0;
+
+	INIT_LIST_HEAD(&extents);
+
+	write_lock(&tree->lock);
+	test_gen = root->fs_info->last_trans_committed;
+	logged_start = start;
+	logged_end = end;
+
+	list_for_each_entry_safe(em, n, &tree->modified_extents, list) {
+		/*
+		 * Skip extents outside our logging range. It's important to do
+		 * it for correctness because if we don't ignore them, we may
+		 * log them before their ordered extent completes, and therefore
+		 * we could log them without logging their respective checksums
+		 * (the checksum items are added to the csum tree at the very
+		 * end of btrfs_finish_ordered_io()). Also leave such extents
+		 * outside of our range in the list, since we may have another
+		 * ranged fsync in the near future that needs them. If an extent
+		 * outside our range corresponds to a hole, log it to avoid
+		 * leaving gaps between extents (fsck will complain when we are
+		 * not using the NO_HOLES feature).
+		 */
+		if ((em->start > end || em->start + em->len <= start) &&
+		    em->block_start != EXTENT_MAP_HOLE)
+			continue;
+
+		list_del_init(&em->list);
+		/*
+		 * Just an arbitrary number, this can be really CPU intensive
+		 * once we start getting a lot of extents, and really once we
+		 * have a bunch of extents we just want to commit since it will
+		 * be faster.
+		 */
+		if (++num > 32768) {
+			list_del_init(&tree->modified_extents);
+			ret = -EFBIG;
+			goto process;
+		}
+
+		if (em->generation <= test_gen)
+			continue;
+
+		/* We log prealloc extents beyond eof later. */
+		if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) &&
+		    em->start >= i_size_read(&inode->vfs_inode))
+			continue;
+
+		if (em->start < logged_start)
+			logged_start = em->start;
+		if ((em->start + em->len - 1) > logged_end)
+			logged_end = em->start + em->len - 1;
+
+		/* Need a ref to keep it from getting evicted from cache */
+		refcount_inc(&em->refs);
+		set_bit(EXTENT_FLAG_LOGGING, &em->flags);
+		list_add_tail(&em->list, &extents);
+		num++;
+	}
+
+	list_sort(NULL, &extents, extent_cmp);
+process:
+	while (!list_empty(&extents)) {
+		em = list_entry(extents.next, struct extent_map, list);
+
+		list_del_init(&em->list);
+
+		/*
+		 * If we had an error we just need to delete everybody from our
+		 * private list.
+		 */
+		if (ret) {
+			clear_em_logging(tree, em);
+			free_extent_map(em);
+			continue;
+		}
+
+		write_unlock(&tree->lock);
+
+		ret = log_one_extent(trans, inode, root, em, path, ctx);
+		write_lock(&tree->lock);
+		clear_em_logging(tree, em);
+		free_extent_map(em);
+	}
+	WARN_ON(!list_empty(&extents));
+	write_unlock(&tree->lock);
+
+	btrfs_release_path(path);
+	if (!ret)
+		ret = btrfs_log_prealloc_extents(trans, inode, path);
+
+	return ret;
+}
+
+static int logged_inode_size(struct btrfs_root *log, struct btrfs_inode *inode,
+			     struct btrfs_path *path, u64 *size_ret)
+{
+	struct btrfs_key key;
+	int ret;
+
+	key.objectid = btrfs_ino(inode);
+	key.type = BTRFS_INODE_ITEM_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, log, &key, path, 0, 0);
+	if (ret < 0) {
+		return ret;
+	} else if (ret > 0) {
+		*size_ret = 0;
+	} else {
+		struct btrfs_inode_item *item;
+
+		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				      struct btrfs_inode_item);
+		*size_ret = btrfs_inode_size(path->nodes[0], item);
+		/*
+		 * If the in-memory inode's i_size is smaller then the inode
+		 * size stored in the btree, return the inode's i_size, so
+		 * that we get a correct inode size after replaying the log
+		 * when before a power failure we had a shrinking truncate
+		 * followed by addition of a new name (rename / new hard link).
+		 * Otherwise return the inode size from the btree, to avoid
+		 * data loss when replaying a log due to previously doing a
+		 * write that expands the inode's size and logging a new name
+		 * immediately after.
+		 */
+		if (*size_ret > inode->vfs_inode.i_size)
+			*size_ret = inode->vfs_inode.i_size;
+	}
+
+	btrfs_release_path(path);
+	return 0;
+}
+
+/*
+ * At the moment we always log all xattrs. This is to figure out at log replay
+ * time which xattrs must have their deletion replayed. If a xattr is missing
+ * in the log tree and exists in the fs/subvol tree, we delete it. This is
+ * because if a xattr is deleted, the inode is fsynced and a power failure
+ * happens, causing the log to be replayed the next time the fs is mounted,
+ * we want the xattr to not exist anymore (same behaviour as other filesystems
+ * with a journal, ext3/4, xfs, f2fs, etc).
+ */
+static int btrfs_log_all_xattrs(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				struct btrfs_inode *inode,
+				struct btrfs_path *path,
+				struct btrfs_path *dst_path)
+{
+	int ret;
+	struct btrfs_key key;
+	const u64 ino = btrfs_ino(inode);
+	int ins_nr = 0;
+	int start_slot = 0;
+
+	key.objectid = ino;
+	key.type = BTRFS_XATTR_ITEM_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		return ret;
+
+	while (true) {
+		int slot = path->slots[0];
+		struct extent_buffer *leaf = path->nodes[0];
+		int nritems = btrfs_header_nritems(leaf);
+
+		if (slot >= nritems) {
+			if (ins_nr > 0) {
+				ret = copy_items(trans, inode, dst_path, path,
+						 start_slot, ins_nr, 1, 0);
+				if (ret < 0)
+					return ret;
+				ins_nr = 0;
+			}
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				return ret;
+			else if (ret > 0)
+				break;
+			continue;
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (key.objectid != ino || key.type != BTRFS_XATTR_ITEM_KEY)
+			break;
+
+		if (ins_nr == 0)
+			start_slot = slot;
+		ins_nr++;
+		path->slots[0]++;
+		cond_resched();
+	}
+	if (ins_nr > 0) {
+		ret = copy_items(trans, inode, dst_path, path,
+				 start_slot, ins_nr, 1, 0);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * When using the NO_HOLES feature if we punched a hole that causes the
+ * deletion of entire leafs or all the extent items of the first leaf (the one
+ * that contains the inode item and references) we may end up not processing
+ * any extents, because there are no leafs with a generation matching the
+ * current transaction that have extent items for our inode. So we need to find
+ * if any holes exist and then log them. We also need to log holes after any
+ * truncate operation that changes the inode's size.
+ */
+static int btrfs_log_holes(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root,
+			   struct btrfs_inode *inode,
+			   struct btrfs_path *path)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_key key;
+	const u64 ino = btrfs_ino(inode);
+	const u64 i_size = i_size_read(&inode->vfs_inode);
+	u64 prev_extent_end = 0;
+	int ret;
+
+	if (!btrfs_fs_incompat(fs_info, NO_HOLES) || i_size == 0)
+		return 0;
+
+	key.objectid = ino;
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		return ret;
+
+	while (true) {
+		struct btrfs_file_extent_item *extent;
+		struct extent_buffer *leaf = path->nodes[0];
+		u64 len;
+
+		if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				return ret;
+			if (ret > 0) {
+				ret = 0;
+				break;
+			}
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY)
+			break;
+
+		/* We have a hole, log it. */
+		if (prev_extent_end < key.offset) {
+			const u64 hole_len = key.offset - prev_extent_end;
+
+			/*
+			 * Release the path to avoid deadlocks with other code
+			 * paths that search the root while holding locks on
+			 * leafs from the log root.
+			 */
+			btrfs_release_path(path);
+			ret = btrfs_insert_file_extent(trans, root->log_root,
+						       ino, prev_extent_end, 0,
+						       0, hole_len, 0, hole_len,
+						       0, 0, 0);
+			if (ret < 0)
+				return ret;
+
+			/*
+			 * Search for the same key again in the root. Since it's
+			 * an extent item and we are holding the inode lock, the
+			 * key must still exist. If it doesn't just emit warning
+			 * and return an error to fall back to a transaction
+			 * commit.
+			 */
+			ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+			if (ret < 0)
+				return ret;
+			if (WARN_ON(ret > 0))
+				return -ENOENT;
+			leaf = path->nodes[0];
+		}
+
+		extent = btrfs_item_ptr(leaf, path->slots[0],
+					struct btrfs_file_extent_item);
+		if (btrfs_file_extent_type(leaf, extent) ==
+		    BTRFS_FILE_EXTENT_INLINE) {
+			len = btrfs_file_extent_ram_bytes(leaf, extent);
+			prev_extent_end = ALIGN(key.offset + len,
+						fs_info->sectorsize);
+		} else {
+			len = btrfs_file_extent_num_bytes(leaf, extent);
+			prev_extent_end = key.offset + len;
+		}
+
+		path->slots[0]++;
+		cond_resched();
+	}
+
+	if (prev_extent_end < i_size) {
+		u64 hole_len;
+
+		btrfs_release_path(path);
+		hole_len = ALIGN(i_size - prev_extent_end, fs_info->sectorsize);
+		ret = btrfs_insert_file_extent(trans, root->log_root,
+					       ino, prev_extent_end, 0, 0,
+					       hole_len, 0, hole_len,
+					       0, 0, 0);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * When we are logging a new inode X, check if it doesn't have a reference that
+ * matches the reference from some other inode Y created in a past transaction
+ * and that was renamed in the current transaction. If we don't do this, then at
+ * log replay time we can lose inode Y (and all its files if it's a directory):
+ *
+ * mkdir /mnt/x
+ * echo "hello world" > /mnt/x/foobar
+ * sync
+ * mv /mnt/x /mnt/y
+ * mkdir /mnt/x                 # or touch /mnt/x
+ * xfs_io -c fsync /mnt/x
+ * <power fail>
+ * mount fs, trigger log replay
+ *
+ * After the log replay procedure, we would lose the first directory and all its
+ * files (file foobar).
+ * For the case where inode Y is not a directory we simply end up losing it:
+ *
+ * echo "123" > /mnt/foo
+ * sync
+ * mv /mnt/foo /mnt/bar
+ * echo "abc" > /mnt/foo
+ * xfs_io -c fsync /mnt/foo
+ * <power fail>
+ *
+ * We also need this for cases where a snapshot entry is replaced by some other
+ * entry (file or directory) otherwise we end up with an unreplayable log due to
+ * attempts to delete the snapshot entry (entry of type BTRFS_ROOT_ITEM_KEY) as
+ * if it were a regular entry:
+ *
+ * mkdir /mnt/x
+ * btrfs subvolume snapshot /mnt /mnt/x/snap
+ * btrfs subvolume delete /mnt/x/snap
+ * rmdir /mnt/x
+ * mkdir /mnt/x
+ * fsync /mnt/x or fsync some new file inside it
+ * <power fail>
+ *
+ * The snapshot delete, rmdir of x, mkdir of a new x and the fsync all happen in
+ * the same transaction.
+ */
+static int btrfs_check_ref_name_override(struct extent_buffer *eb,
+					 const int slot,
+					 const struct btrfs_key *key,
+					 struct btrfs_inode *inode,
+					 u64 *other_ino)
+{
+	int ret;
+	struct btrfs_path *search_path;
+	char *name = NULL;
+	u32 name_len = 0;
+	u32 item_size = btrfs_item_size_nr(eb, slot);
+	u32 cur_offset = 0;
+	unsigned long ptr = btrfs_item_ptr_offset(eb, slot);
+
+	search_path = btrfs_alloc_path();
+	if (!search_path)
+		return -ENOMEM;
+	search_path->search_commit_root = 1;
+	search_path->skip_locking = 1;
+
+	while (cur_offset < item_size) {
+		u64 parent;
+		u32 this_name_len;
+		u32 this_len;
+		unsigned long name_ptr;
+		struct btrfs_dir_item *di;
+
+		if (key->type == BTRFS_INODE_REF_KEY) {
+			struct btrfs_inode_ref *iref;
+
+			iref = (struct btrfs_inode_ref *)(ptr + cur_offset);
+			parent = key->offset;
+			this_name_len = btrfs_inode_ref_name_len(eb, iref);
+			name_ptr = (unsigned long)(iref + 1);
+			this_len = sizeof(*iref) + this_name_len;
+		} else {
+			struct btrfs_inode_extref *extref;
+
+			extref = (struct btrfs_inode_extref *)(ptr +
+							       cur_offset);
+			parent = btrfs_inode_extref_parent(eb, extref);
+			this_name_len = btrfs_inode_extref_name_len(eb, extref);
+			name_ptr = (unsigned long)&extref->name;
+			this_len = sizeof(*extref) + this_name_len;
+		}
+
+		if (this_name_len > name_len) {
+			char *new_name;
+
+			new_name = krealloc(name, this_name_len, GFP_NOFS);
+			if (!new_name) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			name_len = this_name_len;
+			name = new_name;
+		}
+
+		read_extent_buffer(eb, name, name_ptr, this_name_len);
+		di = btrfs_lookup_dir_item(NULL, inode->root, search_path,
+				parent, name, this_name_len, 0);
+		if (di && !IS_ERR(di)) {
+			struct btrfs_key di_key;
+
+			btrfs_dir_item_key_to_cpu(search_path->nodes[0],
+						  di, &di_key);
+			if (di_key.type == BTRFS_INODE_ITEM_KEY) {
+				ret = 1;
+				*other_ino = di_key.objectid;
+			} else {
+				ret = -EAGAIN;
+			}
+			goto out;
+		} else if (IS_ERR(di)) {
+			ret = PTR_ERR(di);
+			goto out;
+		}
+		btrfs_release_path(search_path);
+
+		cur_offset += this_len;
+	}
+	ret = 0;
+out:
+	btrfs_free_path(search_path);
+	kfree(name);
+	return ret;
+}
+
+/* log a single inode in the tree log.
+ * At least one parent directory for this inode must exist in the tree
+ * or be logged already.
+ *
+ * Any items from this inode changed by the current transaction are copied
+ * to the log tree.  An extra reference is taken on any extents in this
+ * file, allowing us to avoid a whole pile of corner cases around logging
+ * blocks that have been removed from the tree.
+ *
+ * See LOG_INODE_ALL and related defines for a description of what inode_only
+ * does.
+ *
+ * This handles both files and directories.
+ */
+static int btrfs_log_inode(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root, struct btrfs_inode *inode,
+			   int inode_only,
+			   const loff_t start,
+			   const loff_t end,
+			   struct btrfs_log_ctx *ctx)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_path *path;
+	struct btrfs_path *dst_path;
+	struct btrfs_key min_key;
+	struct btrfs_key max_key;
+	struct btrfs_root *log = root->log_root;
+	int err = 0;
+	int ret;
+	int nritems;
+	int ins_start_slot = 0;
+	int ins_nr;
+	bool fast_search = false;
+	u64 ino = btrfs_ino(inode);
+	struct extent_map_tree *em_tree = &inode->extent_tree;
+	u64 logged_isize = 0;
+	bool need_log_inode_item = true;
+	bool xattrs_logged = false;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	dst_path = btrfs_alloc_path();
+	if (!dst_path) {
+		btrfs_free_path(path);
+		return -ENOMEM;
+	}
+
+	min_key.objectid = ino;
+	min_key.type = BTRFS_INODE_ITEM_KEY;
+	min_key.offset = 0;
+
+	max_key.objectid = ino;
+
+
+	/* today the code can only do partial logging of directories */
+	if (S_ISDIR(inode->vfs_inode.i_mode) ||
+	    (!test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
+		       &inode->runtime_flags) &&
+	     inode_only >= LOG_INODE_EXISTS))
+		max_key.type = BTRFS_XATTR_ITEM_KEY;
+	else
+		max_key.type = (u8)-1;
+	max_key.offset = (u64)-1;
+
+	/*
+	 * Only run delayed items if we are a dir or a new file.
+	 * Otherwise commit the delayed inode only, which is needed in
+	 * order for the log replay code to mark inodes for link count
+	 * fixup (create temporary BTRFS_TREE_LOG_FIXUP_OBJECTID items).
+	 */
+	if (S_ISDIR(inode->vfs_inode.i_mode) ||
+	    inode->generation > fs_info->last_trans_committed)
+		ret = btrfs_commit_inode_delayed_items(trans, inode);
+	else
+		ret = btrfs_commit_inode_delayed_inode(inode);
+
+	if (ret) {
+		btrfs_free_path(path);
+		btrfs_free_path(dst_path);
+		return ret;
+	}
+
+	if (inode_only == LOG_OTHER_INODE) {
+		inode_only = LOG_INODE_EXISTS;
+		mutex_lock_nested(&inode->log_mutex, SINGLE_DEPTH_NESTING);
+	} else {
+		mutex_lock(&inode->log_mutex);
+	}
+
+	/*
+	 * For symlinks, we must always log their content, which is stored in an
+	 * inline extent, otherwise we could end up with an empty symlink after
+	 * log replay, which is invalid on linux (symlink(2) returns -ENOENT if
+	 * one attempts to create an empty symlink).
+	 * We don't need to worry about flushing delalloc, because when we create
+	 * the inline extent when the symlink is created (we never have delalloc
+	 * for symlinks).
+	 */
+	if (S_ISLNK(inode->vfs_inode.i_mode))
+		inode_only = LOG_INODE_ALL;
+
+	/*
+	 * a brute force approach to making sure we get the most uptodate
+	 * copies of everything.
+	 */
+	if (S_ISDIR(inode->vfs_inode.i_mode)) {
+		int max_key_type = BTRFS_DIR_LOG_INDEX_KEY;
+
+		if (inode_only == LOG_INODE_EXISTS)
+			max_key_type = BTRFS_XATTR_ITEM_KEY;
+		ret = drop_objectid_items(trans, log, path, ino, max_key_type);
+	} else {
+		if (inode_only == LOG_INODE_EXISTS) {
+			/*
+			 * Make sure the new inode item we write to the log has
+			 * the same isize as the current one (if it exists).
+			 * This is necessary to prevent data loss after log
+			 * replay, and also to prevent doing a wrong expanding
+			 * truncate - for e.g. create file, write 4K into offset
+			 * 0, fsync, write 4K into offset 4096, add hard link,
+			 * fsync some other file (to sync log), power fail - if
+			 * we use the inode's current i_size, after log replay
+			 * we get a 8Kb file, with the last 4Kb extent as a hole
+			 * (zeroes), as if an expanding truncate happened,
+			 * instead of getting a file of 4Kb only.
+			 */
+			err = logged_inode_size(log, inode, path, &logged_isize);
+			if (err)
+				goto out_unlock;
+		}
+		if (test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
+			     &inode->runtime_flags)) {
+			if (inode_only == LOG_INODE_EXISTS) {
+				max_key.type = BTRFS_XATTR_ITEM_KEY;
+				ret = drop_objectid_items(trans, log, path, ino,
+							  max_key.type);
+			} else {
+				clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
+					  &inode->runtime_flags);
+				clear_bit(BTRFS_INODE_COPY_EVERYTHING,
+					  &inode->runtime_flags);
+				while(1) {
+					ret = btrfs_truncate_inode_items(trans,
+						log, &inode->vfs_inode, 0, 0);
+					if (ret != -EAGAIN)
+						break;
+				}
+			}
+		} else if (test_and_clear_bit(BTRFS_INODE_COPY_EVERYTHING,
+					      &inode->runtime_flags) ||
+			   inode_only == LOG_INODE_EXISTS) {
+			if (inode_only == LOG_INODE_ALL)
+				fast_search = true;
+			max_key.type = BTRFS_XATTR_ITEM_KEY;
+			ret = drop_objectid_items(trans, log, path, ino,
+						  max_key.type);
+		} else {
+			if (inode_only == LOG_INODE_ALL)
+				fast_search = true;
+			goto log_extents;
+		}
+
+	}
+	if (ret) {
+		err = ret;
+		goto out_unlock;
+	}
+
+	while (1) {
+		ins_nr = 0;
+		ret = btrfs_search_forward(root, &min_key,
+					   path, trans->transid);
+		if (ret < 0) {
+			err = ret;
+			goto out_unlock;
+		}
+		if (ret != 0)
+			break;
+again:
+		/* note, ins_nr might be > 0 here, cleanup outside the loop */
+		if (min_key.objectid != ino)
+			break;
+		if (min_key.type > max_key.type)
+			break;
+
+		if (min_key.type == BTRFS_INODE_ITEM_KEY)
+			need_log_inode_item = false;
+
+		if ((min_key.type == BTRFS_INODE_REF_KEY ||
+		     min_key.type == BTRFS_INODE_EXTREF_KEY) &&
+		    inode->generation == trans->transid) {
+			u64 other_ino = 0;
+
+			ret = btrfs_check_ref_name_override(path->nodes[0],
+					path->slots[0], &min_key, inode,
+					&other_ino);
+			if (ret < 0) {
+				err = ret;
+				goto out_unlock;
+			} else if (ret > 0 && ctx &&
+				   other_ino != btrfs_ino(BTRFS_I(ctx->inode))) {
+				struct btrfs_key inode_key;
+				struct inode *other_inode;
+
+				if (ins_nr > 0) {
+					ins_nr++;
+				} else {
+					ins_nr = 1;
+					ins_start_slot = path->slots[0];
+				}
+				ret = copy_items(trans, inode, dst_path, path,
+						 ins_start_slot,
+						 ins_nr, inode_only,
+						 logged_isize);
+				if (ret < 0) {
+					err = ret;
+					goto out_unlock;
+				}
+				ins_nr = 0;
+				btrfs_release_path(path);
+				inode_key.objectid = other_ino;
+				inode_key.type = BTRFS_INODE_ITEM_KEY;
+				inode_key.offset = 0;
+				other_inode = btrfs_iget(fs_info->sb,
+							 &inode_key, root,
+							 NULL);
+				/*
+				 * If the other inode that had a conflicting dir
+				 * entry was deleted in the current transaction,
+				 * we don't need to do more work nor fallback to
+				 * a transaction commit.
+				 */
+				if (other_inode == ERR_PTR(-ENOENT)) {
+					goto next_key;
+				} else if (IS_ERR(other_inode)) {
+					err = PTR_ERR(other_inode);
+					goto out_unlock;
+				}
+				/*
+				 * We are safe logging the other inode without
+				 * acquiring its i_mutex as long as we log with
+				 * the LOG_INODE_EXISTS mode. We're safe against
+				 * concurrent renames of the other inode as well
+				 * because during a rename we pin the log and
+				 * update the log with the new name before we
+				 * unpin it.
+				 */
+				err = btrfs_log_inode(trans, root,
+						BTRFS_I(other_inode),
+						LOG_OTHER_INODE, 0, LLONG_MAX,
+						ctx);
+				btrfs_add_delayed_iput(other_inode);
+				if (err)
+					goto out_unlock;
+				else
+					goto next_key;
+			}
+		}
+
+		/* Skip xattrs, we log them later with btrfs_log_all_xattrs() */
+		if (min_key.type == BTRFS_XATTR_ITEM_KEY) {
+			if (ins_nr == 0)
+				goto next_slot;
+			ret = copy_items(trans, inode, dst_path, path,
+					 ins_start_slot,
+					 ins_nr, inode_only, logged_isize);
+			if (ret < 0) {
+				err = ret;
+				goto out_unlock;
+			}
+			ins_nr = 0;
+			goto next_slot;
+		}
+
+		if (ins_nr && ins_start_slot + ins_nr == path->slots[0]) {
+			ins_nr++;
+			goto next_slot;
+		} else if (!ins_nr) {
+			ins_start_slot = path->slots[0];
+			ins_nr = 1;
+			goto next_slot;
+		}
+
+		ret = copy_items(trans, inode, dst_path, path,
+				 ins_start_slot, ins_nr, inode_only,
+				 logged_isize);
+		if (ret < 0) {
+			err = ret;
+			goto out_unlock;
+		}
+		ins_nr = 1;
+		ins_start_slot = path->slots[0];
+next_slot:
+
+		nritems = btrfs_header_nritems(path->nodes[0]);
+		path->slots[0]++;
+		if (path->slots[0] < nritems) {
+			btrfs_item_key_to_cpu(path->nodes[0], &min_key,
+					      path->slots[0]);
+			goto again;
+		}
+		if (ins_nr) {
+			ret = copy_items(trans, inode, dst_path, path,
+					 ins_start_slot,
+					 ins_nr, inode_only, logged_isize);
+			if (ret < 0) {
+				err = ret;
+				goto out_unlock;
+			}
+			ins_nr = 0;
+		}
+		btrfs_release_path(path);
+next_key:
+		if (min_key.offset < (u64)-1) {
+			min_key.offset++;
+		} else if (min_key.type < max_key.type) {
+			min_key.type++;
+			min_key.offset = 0;
+		} else {
+			break;
+		}
+	}
+	if (ins_nr) {
+		ret = copy_items(trans, inode, dst_path, path,
+				 ins_start_slot, ins_nr, inode_only,
+				 logged_isize);
+		if (ret < 0) {
+			err = ret;
+			goto out_unlock;
+		}
+		ins_nr = 0;
+	}
+
+	btrfs_release_path(path);
+	btrfs_release_path(dst_path);
+	err = btrfs_log_all_xattrs(trans, root, inode, path, dst_path);
+	if (err)
+		goto out_unlock;
+	xattrs_logged = true;
+	if (max_key.type >= BTRFS_EXTENT_DATA_KEY && !fast_search) {
+		btrfs_release_path(path);
+		btrfs_release_path(dst_path);
+		err = btrfs_log_holes(trans, root, inode, path);
+		if (err)
+			goto out_unlock;
+	}
+log_extents:
+	btrfs_release_path(path);
+	btrfs_release_path(dst_path);
+	if (need_log_inode_item) {
+		err = log_inode_item(trans, log, dst_path, inode);
+		if (!err && !xattrs_logged) {
+			err = btrfs_log_all_xattrs(trans, root, inode, path,
+						   dst_path);
+			btrfs_release_path(path);
+		}
+		if (err)
+			goto out_unlock;
+	}
+	if (fast_search) {
+		ret = btrfs_log_changed_extents(trans, root, inode, dst_path,
+						ctx, start, end);
+		if (ret) {
+			err = ret;
+			goto out_unlock;
+		}
+	} else if (inode_only == LOG_INODE_ALL) {
+		struct extent_map *em, *n;
+
+		write_lock(&em_tree->lock);
+		/*
+		 * We can't just remove every em if we're called for a ranged
+		 * fsync - that is, one that doesn't cover the whole possible
+		 * file range (0 to LLONG_MAX). This is because we can have
+		 * em's that fall outside the range we're logging and therefore
+		 * their ordered operations haven't completed yet
+		 * (btrfs_finish_ordered_io() not invoked yet). This means we
+		 * didn't get their respective file extent item in the fs/subvol
+		 * tree yet, and need to let the next fast fsync (one which
+		 * consults the list of modified extent maps) find the em so
+		 * that it logs a matching file extent item and waits for the
+		 * respective ordered operation to complete (if it's still
+		 * running).
+		 *
+		 * Removing every em outside the range we're logging would make
+		 * the next fast fsync not log their matching file extent items,
+		 * therefore making us lose data after a log replay.
+		 */
+		list_for_each_entry_safe(em, n, &em_tree->modified_extents,
+					 list) {
+			const u64 mod_end = em->mod_start + em->mod_len - 1;
+
+			if (em->mod_start >= start && mod_end <= end)
+				list_del_init(&em->list);
+		}
+		write_unlock(&em_tree->lock);
+	}
+
+	if (inode_only == LOG_INODE_ALL && S_ISDIR(inode->vfs_inode.i_mode)) {
+		ret = log_directory_changes(trans, root, inode, path, dst_path,
+					ctx);
+		if (ret) {
+			err = ret;
+			goto out_unlock;
+		}
+	}
+
+	/*
+	 * Don't update last_log_commit if we logged that an inode exists after
+	 * it was loaded to memory (full_sync bit set).
+	 * This is to prevent data loss when we do a write to the inode, then
+	 * the inode gets evicted after all delalloc was flushed, then we log
+	 * it exists (due to a rename for example) and then fsync it. This last
+	 * fsync would do nothing (not logging the extents previously written).
+	 */
+	spin_lock(&inode->lock);
+	inode->logged_trans = trans->transid;
+	if (inode_only != LOG_INODE_EXISTS ||
+	    !test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags))
+		inode->last_log_commit = inode->last_sub_trans;
+	spin_unlock(&inode->lock);
+out_unlock:
+	mutex_unlock(&inode->log_mutex);
+
+	btrfs_free_path(path);
+	btrfs_free_path(dst_path);
+	return err;
+}
+
+/*
+ * Check if we must fallback to a transaction commit when logging an inode.
+ * This must be called after logging the inode and is used only in the context
+ * when fsyncing an inode requires the need to log some other inode - in which
+ * case we can't lock the i_mutex of each other inode we need to log as that
+ * can lead to deadlocks with concurrent fsync against other inodes (as we can
+ * log inodes up or down in the hierarchy) or rename operations for example. So
+ * we take the log_mutex of the inode after we have logged it and then check for
+ * its last_unlink_trans value - this is safe because any task setting
+ * last_unlink_trans must take the log_mutex and it must do this before it does
+ * the actual unlink operation, so if we do this check before a concurrent task
+ * sets last_unlink_trans it means we've logged a consistent version/state of
+ * all the inode items, otherwise we are not sure and must do a transaction
+ * commit (the concurrent task might have only updated last_unlink_trans before
+ * we logged the inode or it might have also done the unlink).
+ */
+static bool btrfs_must_commit_transaction(struct btrfs_trans_handle *trans,
+					  struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	bool ret = false;
+
+	mutex_lock(&inode->log_mutex);
+	if (inode->last_unlink_trans > fs_info->last_trans_committed) {
+		/*
+		 * Make sure any commits to the log are forced to be full
+		 * commits.
+		 */
+		btrfs_set_log_full_commit(fs_info, trans);
+		ret = true;
+	}
+	mutex_unlock(&inode->log_mutex);
+
+	return ret;
+}
+
+/*
+ * follow the dentry parent pointers up the chain and see if any
+ * of the directories in it require a full commit before they can
+ * be logged.  Returns zero if nothing special needs to be done or 1 if
+ * a full commit is required.
+ */
+static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
+					       struct btrfs_inode *inode,
+					       struct dentry *parent,
+					       struct super_block *sb,
+					       u64 last_committed)
+{
+	int ret = 0;
+	struct dentry *old_parent = NULL;
+
+	/*
+	 * for regular files, if its inode is already on disk, we don't
+	 * have to worry about the parents at all.  This is because
+	 * we can use the last_unlink_trans field to record renames
+	 * and other fun in this file.
+	 */
+	if (S_ISREG(inode->vfs_inode.i_mode) &&
+	    inode->generation <= last_committed &&
+	    inode->last_unlink_trans <= last_committed)
+		goto out;
+
+	if (!S_ISDIR(inode->vfs_inode.i_mode)) {
+		if (!parent || d_really_is_negative(parent) || sb != parent->d_sb)
+			goto out;
+		inode = BTRFS_I(d_inode(parent));
+	}
+
+	while (1) {
+		if (btrfs_must_commit_transaction(trans, inode)) {
+			ret = 1;
+			break;
+		}
+
+		if (!parent || d_really_is_negative(parent) || sb != parent->d_sb)
+			break;
+
+		if (IS_ROOT(parent)) {
+			inode = BTRFS_I(d_inode(parent));
+			if (btrfs_must_commit_transaction(trans, inode))
+				ret = 1;
+			break;
+		}
+
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
+		inode = BTRFS_I(d_inode(parent));
+
+	}
+	dput(old_parent);
+out:
+	return ret;
+}
+
+struct btrfs_dir_list {
+	u64 ino;
+	struct list_head list;
+};
+
+/*
+ * Log the inodes of the new dentries of a directory. See log_dir_items() for
+ * details about the why it is needed.
+ * This is a recursive operation - if an existing dentry corresponds to a
+ * directory, that directory's new entries are logged too (same behaviour as
+ * ext3/4, xfs, f2fs, reiserfs, nilfs2). Note that when logging the inodes
+ * the dentries point to we do not lock their i_mutex, otherwise lockdep
+ * complains about the following circular lock dependency / possible deadlock:
+ *
+ *        CPU0                                        CPU1
+ *        ----                                        ----
+ * lock(&type->i_mutex_dir_key#3/2);
+ *                                            lock(sb_internal#2);
+ *                                            lock(&type->i_mutex_dir_key#3/2);
+ * lock(&sb->s_type->i_mutex_key#14);
+ *
+ * Where sb_internal is the lock (a counter that works as a lock) acquired by
+ * sb_start_intwrite() in btrfs_start_transaction().
+ * Not locking i_mutex of the inodes is still safe because:
+ *
+ * 1) For regular files we log with a mode of LOG_INODE_EXISTS. It's possible
+ *    that while logging the inode new references (names) are added or removed
+ *    from the inode, leaving the logged inode item with a link count that does
+ *    not match the number of logged inode reference items. This is fine because
+ *    at log replay time we compute the real number of links and correct the
+ *    link count in the inode item (see replay_one_buffer() and
+ *    link_to_fixup_dir());
+ *
+ * 2) For directories we log with a mode of LOG_INODE_ALL. It's possible that
+ *    while logging the inode's items new items with keys BTRFS_DIR_ITEM_KEY and
+ *    BTRFS_DIR_INDEX_KEY are added to fs/subvol tree and the logged inode item
+ *    has a size that doesn't match the sum of the lengths of all the logged
+ *    names. This does not result in a problem because if a dir_item key is
+ *    logged but its matching dir_index key is not logged, at log replay time we
+ *    don't use it to replay the respective name (see replay_one_name()). On the
+ *    other hand if only the dir_index key ends up being logged, the respective
+ *    name is added to the fs/subvol tree with both the dir_item and dir_index
+ *    keys created (see replay_one_name()).
+ *    The directory's inode item with a wrong i_size is not a problem as well,
+ *    since we don't use it at log replay time to set the i_size in the inode
+ *    item of the fs/subvol tree (see overwrite_item()).
+ */
+static int log_new_dir_dentries(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				struct btrfs_inode *start_inode,
+				struct btrfs_log_ctx *ctx)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_root *log = root->log_root;
+	struct btrfs_path *path;
+	LIST_HEAD(dir_list);
+	struct btrfs_dir_list *dir_elem;
+	int ret = 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	dir_elem = kmalloc(sizeof(*dir_elem), GFP_NOFS);
+	if (!dir_elem) {
+		btrfs_free_path(path);
+		return -ENOMEM;
+	}
+	dir_elem->ino = btrfs_ino(start_inode);
+	list_add_tail(&dir_elem->list, &dir_list);
+
+	while (!list_empty(&dir_list)) {
+		struct extent_buffer *leaf;
+		struct btrfs_key min_key;
+		int nritems;
+		int i;
+
+		dir_elem = list_first_entry(&dir_list, struct btrfs_dir_list,
+					    list);
+		if (ret)
+			goto next_dir_inode;
+
+		min_key.objectid = dir_elem->ino;
+		min_key.type = BTRFS_DIR_ITEM_KEY;
+		min_key.offset = 0;
+again:
+		btrfs_release_path(path);
+		ret = btrfs_search_forward(log, &min_key, path, trans->transid);
+		if (ret < 0) {
+			goto next_dir_inode;
+		} else if (ret > 0) {
+			ret = 0;
+			goto next_dir_inode;
+		}
+
+process_leaf:
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		for (i = path->slots[0]; i < nritems; i++) {
+			struct btrfs_dir_item *di;
+			struct btrfs_key di_key;
+			struct inode *di_inode;
+			struct btrfs_dir_list *new_dir_elem;
+			int log_mode = LOG_INODE_EXISTS;
+			int type;
+
+			btrfs_item_key_to_cpu(leaf, &min_key, i);
+			if (min_key.objectid != dir_elem->ino ||
+			    min_key.type != BTRFS_DIR_ITEM_KEY)
+				goto next_dir_inode;
+
+			di = btrfs_item_ptr(leaf, i, struct btrfs_dir_item);
+			type = btrfs_dir_type(leaf, di);
+			if (btrfs_dir_transid(leaf, di) < trans->transid &&
+			    type != BTRFS_FT_DIR)
+				continue;
+			btrfs_dir_item_key_to_cpu(leaf, di, &di_key);
+			if (di_key.type == BTRFS_ROOT_ITEM_KEY)
+				continue;
+
+			btrfs_release_path(path);
+			di_inode = btrfs_iget(fs_info->sb, &di_key, root, NULL);
+			if (IS_ERR(di_inode)) {
+				ret = PTR_ERR(di_inode);
+				goto next_dir_inode;
+			}
+
+			if (btrfs_inode_in_log(BTRFS_I(di_inode), trans->transid)) {
+				btrfs_add_delayed_iput(di_inode);
+				break;
+			}
+
+			ctx->log_new_dentries = false;
+			if (type == BTRFS_FT_DIR)
+				log_mode = LOG_INODE_ALL;
+			ret = btrfs_log_inode(trans, root, BTRFS_I(di_inode),
+					      log_mode, 0, LLONG_MAX, ctx);
+			if (!ret &&
+			    btrfs_must_commit_transaction(trans, BTRFS_I(di_inode)))
+				ret = 1;
+			btrfs_add_delayed_iput(di_inode);
+			if (ret)
+				goto next_dir_inode;
+			if (ctx->log_new_dentries) {
+				new_dir_elem = kmalloc(sizeof(*new_dir_elem),
+						       GFP_NOFS);
+				if (!new_dir_elem) {
+					ret = -ENOMEM;
+					goto next_dir_inode;
+				}
+				new_dir_elem->ino = di_key.objectid;
+				list_add_tail(&new_dir_elem->list, &dir_list);
+			}
+			break;
+		}
+		if (i == nritems) {
+			ret = btrfs_next_leaf(log, path);
+			if (ret < 0) {
+				goto next_dir_inode;
+			} else if (ret > 0) {
+				ret = 0;
+				goto next_dir_inode;
+			}
+			goto process_leaf;
+		}
+		if (min_key.offset < (u64)-1) {
+			min_key.offset++;
+			goto again;
+		}
+next_dir_inode:
+		list_del(&dir_elem->list);
+		kfree(dir_elem);
+	}
+
+	btrfs_free_path(path);
+	return ret;
+}
+
+static int btrfs_log_all_parents(struct btrfs_trans_handle *trans,
+				 struct btrfs_inode *inode,
+				 struct btrfs_log_ctx *ctx)
+{
+	struct btrfs_fs_info *fs_info = trans->fs_info;
+	int ret;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	struct btrfs_root *root = inode->root;
+	const u64 ino = btrfs_ino(inode);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	path->skip_locking = 1;
+	path->search_commit_root = 1;
+
+	key.objectid = ino;
+	key.type = BTRFS_INODE_REF_KEY;
+	key.offset = 0;
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+
+	while (true) {
+		struct extent_buffer *leaf = path->nodes[0];
+		int slot = path->slots[0];
+		u32 cur_offset = 0;
+		u32 item_size;
+		unsigned long ptr;
+
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			else if (ret > 0)
+				break;
+			continue;
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		/* BTRFS_INODE_EXTREF_KEY is BTRFS_INODE_REF_KEY + 1 */
+		if (key.objectid != ino || key.type > BTRFS_INODE_EXTREF_KEY)
+			break;
+
+		item_size = btrfs_item_size_nr(leaf, slot);
+		ptr = btrfs_item_ptr_offset(leaf, slot);
+		while (cur_offset < item_size) {
+			struct btrfs_key inode_key;
+			struct inode *dir_inode;
+
+			inode_key.type = BTRFS_INODE_ITEM_KEY;
+			inode_key.offset = 0;
+
+			if (key.type == BTRFS_INODE_EXTREF_KEY) {
+				struct btrfs_inode_extref *extref;
+
+				extref = (struct btrfs_inode_extref *)
+					(ptr + cur_offset);
+				inode_key.objectid = btrfs_inode_extref_parent(
+					leaf, extref);
+				cur_offset += sizeof(*extref);
+				cur_offset += btrfs_inode_extref_name_len(leaf,
+					extref);
+			} else {
+				inode_key.objectid = key.offset;
+				cur_offset = item_size;
+			}
+
+			dir_inode = btrfs_iget(fs_info->sb, &inode_key,
+					       root, NULL);
+			/*
+			 * If the parent inode was deleted, return an error to
+			 * fallback to a transaction commit. This is to prevent
+			 * getting an inode that was moved from one parent A to
+			 * a parent B, got its former parent A deleted and then
+			 * it got fsync'ed, from existing at both parents after
+			 * a log replay (and the old parent still existing).
+			 * Example:
+			 *
+			 * mkdir /mnt/A
+			 * mkdir /mnt/B
+			 * touch /mnt/B/bar
+			 * sync
+			 * mv /mnt/B/bar /mnt/A/bar
+			 * mv -T /mnt/A /mnt/B
+			 * fsync /mnt/B/bar
+			 * <power fail>
+			 *
+			 * If we ignore the old parent B which got deleted,
+			 * after a log replay we would have file bar linked
+			 * at both parents and the old parent B would still
+			 * exist.
+			 */
+			if (IS_ERR(dir_inode)) {
+				ret = PTR_ERR(dir_inode);
+				goto out;
+			}
+
+			if (ctx)
+				ctx->log_new_dentries = false;
+			ret = btrfs_log_inode(trans, root, BTRFS_I(dir_inode),
+					      LOG_INODE_ALL, 0, LLONG_MAX, ctx);
+			if (!ret &&
+			    btrfs_must_commit_transaction(trans, BTRFS_I(dir_inode)))
+				ret = 1;
+			if (!ret && ctx && ctx->log_new_dentries)
+				ret = log_new_dir_dentries(trans, root,
+						   BTRFS_I(dir_inode), ctx);
+			btrfs_add_delayed_iput(dir_inode);
+			if (ret)
+				goto out;
+		}
+		path->slots[0]++;
+	}
+	ret = 0;
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * helper function around btrfs_log_inode to make sure newly created
+ * parent directories also end up in the log.  A minimal inode and backref
+ * only logging is done of any parent directories that are older than
+ * the last committed transaction
+ */
+static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
+				  struct btrfs_inode *inode,
+				  struct dentry *parent,
+				  const loff_t start,
+				  const loff_t end,
+				  int inode_only,
+				  struct btrfs_log_ctx *ctx)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct super_block *sb;
+	struct dentry *old_parent = NULL;
+	int ret = 0;
+	u64 last_committed = fs_info->last_trans_committed;
+	bool log_dentries = false;
+	struct btrfs_inode *orig_inode = inode;
+
+	sb = inode->vfs_inode.i_sb;
+
+	if (btrfs_test_opt(fs_info, NOTREELOG)) {
+		ret = 1;
+		goto end_no_trans;
+	}
+
+	/*
+	 * The prev transaction commit doesn't complete, we need do
+	 * full commit by ourselves.
+	 */
+	if (fs_info->last_trans_log_full_commit >
+	    fs_info->last_trans_committed) {
+		ret = 1;
+		goto end_no_trans;
+	}
+
+	if (btrfs_root_refs(&root->root_item) == 0) {
+		ret = 1;
+		goto end_no_trans;
+	}
+
+	ret = check_parent_dirs_for_sync(trans, inode, parent, sb,
+			last_committed);
+	if (ret)
+		goto end_no_trans;
+
+	/*
+	 * Skip already logged inodes or inodes corresponding to tmpfiles
+	 * (since logging them is pointless, a link count of 0 means they
+	 * will never be accessible).
+	 */
+	if (btrfs_inode_in_log(inode, trans->transid) ||
+	    inode->vfs_inode.i_nlink == 0) {
+		ret = BTRFS_NO_LOG_SYNC;
+		goto end_no_trans;
+	}
+
+	ret = start_log_trans(trans, root, ctx);
+	if (ret)
+		goto end_no_trans;
+
+	ret = btrfs_log_inode(trans, root, inode, inode_only, start, end, ctx);
+	if (ret)
+		goto end_trans;
+
+	/*
+	 * for regular files, if its inode is already on disk, we don't
+	 * have to worry about the parents at all.  This is because
+	 * we can use the last_unlink_trans field to record renames
+	 * and other fun in this file.
+	 */
+	if (S_ISREG(inode->vfs_inode.i_mode) &&
+	    inode->generation <= last_committed &&
+	    inode->last_unlink_trans <= last_committed) {
+		ret = 0;
+		goto end_trans;
+	}
+
+	if (S_ISDIR(inode->vfs_inode.i_mode) && ctx && ctx->log_new_dentries)
+		log_dentries = true;
+
+	/*
+	 * On unlink we must make sure all our current and old parent directory
+	 * inodes are fully logged. This is to prevent leaving dangling
+	 * directory index entries in directories that were our parents but are
+	 * not anymore. Not doing this results in old parent directory being
+	 * impossible to delete after log replay (rmdir will always fail with
+	 * error -ENOTEMPTY).
+	 *
+	 * Example 1:
+	 *
+	 * mkdir testdir
+	 * touch testdir/foo
+	 * ln testdir/foo testdir/bar
+	 * sync
+	 * unlink testdir/bar
+	 * xfs_io -c fsync testdir/foo
+	 * <power failure>
+	 * mount fs, triggers log replay
+	 *
+	 * If we don't log the parent directory (testdir), after log replay the
+	 * directory still has an entry pointing to the file inode using the bar
+	 * name, but a matching BTRFS_INODE_[REF|EXTREF]_KEY does not exist and
+	 * the file inode has a link count of 1.
+	 *
+	 * Example 2:
+	 *
+	 * mkdir testdir
+	 * touch foo
+	 * ln foo testdir/foo2
+	 * ln foo testdir/foo3
+	 * sync
+	 * unlink testdir/foo3
+	 * xfs_io -c fsync foo
+	 * <power failure>
+	 * mount fs, triggers log replay
+	 *
+	 * Similar as the first example, after log replay the parent directory
+	 * testdir still has an entry pointing to the inode file with name foo3
+	 * but the file inode does not have a matching BTRFS_INODE_REF_KEY item
+	 * and has a link count of 2.
+	 */
+	if (inode->last_unlink_trans > last_committed) {
+		ret = btrfs_log_all_parents(trans, orig_inode, ctx);
+		if (ret)
+			goto end_trans;
+	}
+
+	/*
+	 * If a new hard link was added to the inode in the current transaction
+	 * and its link count is now greater than 1, we need to fallback to a
+	 * transaction commit, otherwise we can end up not logging all its new
+	 * parents for all the hard links. Here just from the dentry used to
+	 * fsync, we can not visit the ancestor inodes for all the other hard
+	 * links to figure out if any is new, so we fallback to a transaction
+	 * commit (instead of adding a lot of complexity of scanning a btree,
+	 * since this scenario is not a common use case).
+	 */
+	if (inode->vfs_inode.i_nlink > 1 &&
+	    inode->last_link_trans > last_committed) {
+		ret = -EMLINK;
+		goto end_trans;
+	}
+
+	while (1) {
+		if (!parent || d_really_is_negative(parent) || sb != parent->d_sb)
+			break;
+
+		inode = BTRFS_I(d_inode(parent));
+		if (root != inode->root)
+			break;
+
+		if (inode->generation > last_committed) {
+			ret = btrfs_log_inode(trans, root, inode,
+					LOG_INODE_EXISTS, 0, LLONG_MAX, ctx);
+			if (ret)
+				goto end_trans;
+		}
+		if (IS_ROOT(parent))
+			break;
+
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
+	}
+	if (log_dentries)
+		ret = log_new_dir_dentries(trans, root, orig_inode, ctx);
+	else
+		ret = 0;
+end_trans:
+	dput(old_parent);
+	if (ret < 0) {
+		btrfs_set_log_full_commit(fs_info, trans);
+		ret = 1;
+	}
+
+	if (ret)
+		btrfs_remove_log_ctx(root, ctx);
+	btrfs_end_log_trans(root);
+end_no_trans:
+	return ret;
+}
+
+/*
+ * it is not safe to log dentry if the chunk root has added new
+ * chunks.  This returns 0 if the dentry was logged, and 1 otherwise.
+ * If this returns 1, you must commit the transaction to safely get your
+ * data on disk.
+ */
+int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans,
+			  struct dentry *dentry,
+			  const loff_t start,
+			  const loff_t end,
+			  struct btrfs_log_ctx *ctx)
+{
+	struct dentry *parent = dget_parent(dentry);
+	int ret;
+
+	ret = btrfs_log_inode_parent(trans, BTRFS_I(d_inode(dentry)), parent,
+				     start, end, LOG_INODE_ALL, ctx);
+	dput(parent);
+
+	return ret;
+}
+
+/*
+ * should be called during mount to recover any replay any log trees
+ * from the FS
+ */
+int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
+{
+	int ret;
+	struct btrfs_path *path;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	struct btrfs_key tmp_key;
+	struct btrfs_root *log;
+	struct btrfs_fs_info *fs_info = log_root_tree->fs_info;
+	struct walk_control wc = {
+		.process_func = process_one_buffer,
+		.stage = 0,
+	};
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	set_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags);
+
+	trans = btrfs_start_transaction(fs_info->tree_root, 0);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto error;
+	}
+
+	wc.trans = trans;
+	wc.pin = 1;
+
+	ret = walk_log_tree(trans, log_root_tree, &wc);
+	if (ret) {
+		btrfs_handle_fs_error(fs_info, ret,
+			"Failed to pin buffers while recovering log root tree.");
+		goto error;
+	}
+
+again:
+	key.objectid = BTRFS_TREE_LOG_OBJECTID;
+	key.offset = (u64)-1;
+	key.type = BTRFS_ROOT_ITEM_KEY;
+
+	while (1) {
+		ret = btrfs_search_slot(NULL, log_root_tree, &key, path, 0, 0);
+
+		if (ret < 0) {
+			btrfs_handle_fs_error(fs_info, ret,
+				    "Couldn't find tree log root.");
+			goto error;
+		}
+		if (ret > 0) {
+			if (path->slots[0] == 0)
+				break;
+			path->slots[0]--;
+		}
+		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
+				      path->slots[0]);
+		btrfs_release_path(path);
+		if (found_key.objectid != BTRFS_TREE_LOG_OBJECTID)
+			break;
+
+		log = btrfs_read_fs_root(log_root_tree, &found_key);
+		if (IS_ERR(log)) {
+			ret = PTR_ERR(log);
+			btrfs_handle_fs_error(fs_info, ret,
+				    "Couldn't read tree log root.");
+			goto error;
+		}
+
+		tmp_key.objectid = found_key.offset;
+		tmp_key.type = BTRFS_ROOT_ITEM_KEY;
+		tmp_key.offset = (u64)-1;
+
+		wc.replay_dest = btrfs_read_fs_root_no_name(fs_info, &tmp_key);
+		if (IS_ERR(wc.replay_dest)) {
+			ret = PTR_ERR(wc.replay_dest);
+
+			/*
+			 * We didn't find the subvol, likely because it was
+			 * deleted.  This is ok, simply skip this log and go to
+			 * the next one.
+			 *
+			 * We need to exclude the root because we can't have
+			 * other log replays overwriting this log as we'll read
+			 * it back in a few more times.  This will keep our
+			 * block from being modified, and we'll just bail for
+			 * each subsequent pass.
+			 */
+			if (ret == -ENOENT)
+				ret = btrfs_pin_extent_for_log_replay(fs_info,
+							log->node->start,
+							log->node->len);
+			free_extent_buffer(log->node);
+			free_extent_buffer(log->commit_root);
+			kfree(log);
+
+			if (!ret)
+				goto next;
+			btrfs_handle_fs_error(fs_info, ret,
+				"Couldn't read target root for tree log recovery.");
+			goto error;
+		}
+
+		wc.replay_dest->log_root = log;
+		btrfs_record_root_in_trans(trans, wc.replay_dest);
+		ret = walk_log_tree(trans, log, &wc);
+
+		if (!ret && wc.stage == LOG_WALK_REPLAY_ALL) {
+			ret = fixup_inode_link_counts(trans, wc.replay_dest,
+						      path);
+		}
+
+		if (!ret && wc.stage == LOG_WALK_REPLAY_ALL) {
+			struct btrfs_root *root = wc.replay_dest;
+
+			btrfs_release_path(path);
+
+			/*
+			 * We have just replayed everything, and the highest
+			 * objectid of fs roots probably has changed in case
+			 * some inode_item's got replayed.
+			 *
+			 * root->objectid_mutex is not acquired as log replay
+			 * could only happen during mount.
+			 */
+			ret = btrfs_find_highest_objectid(root,
+						  &root->highest_objectid);
+		}
+
+		wc.replay_dest->log_root = NULL;
+		free_extent_buffer(log->node);
+		free_extent_buffer(log->commit_root);
+		kfree(log);
+
+		if (ret)
+			goto error;
+next:
+		if (found_key.offset == 0)
+			break;
+		key.offset = found_key.offset - 1;
+	}
+	btrfs_release_path(path);
+
+	/* step one is to pin it all, step two is to replay just inodes */
+	if (wc.pin) {
+		wc.pin = 0;
+		wc.process_func = replay_one_buffer;
+		wc.stage = LOG_WALK_REPLAY_INODES;
+		goto again;
+	}
+	/* step three is to replay everything */
+	if (wc.stage < LOG_WALK_REPLAY_ALL) {
+		wc.stage++;
+		goto again;
+	}
+
+	btrfs_free_path(path);
+
+	/* step 4: commit the transaction, which also unpins the blocks */
+	ret = btrfs_commit_transaction(trans);
+	if (ret)
+		return ret;
+
+	free_extent_buffer(log_root_tree->node);
+	log_root_tree->log_root = NULL;
+	clear_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags);
+	kfree(log_root_tree);
+
+	return 0;
+error:
+	if (wc.trans)
+		btrfs_end_transaction(wc.trans);
+	clear_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags);
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * there are some corner cases where we want to force a full
+ * commit instead of allowing a directory to be logged.
+ *
+ * They revolve around files there were unlinked from the directory, and
+ * this function updates the parent directory so that a full commit is
+ * properly done if it is fsync'd later after the unlinks are done.
+ *
+ * Must be called before the unlink operations (updates to the subvolume tree,
+ * inodes, etc) are done.
+ */
+void btrfs_record_unlink_dir(struct btrfs_trans_handle *trans,
+			     struct btrfs_inode *dir, struct btrfs_inode *inode,
+			     int for_rename)
+{
+	/*
+	 * when we're logging a file, if it hasn't been renamed
+	 * or unlinked, and its inode is fully committed on disk,
+	 * we don't have to worry about walking up the directory chain
+	 * to log its parents.
+	 *
+	 * So, we use the last_unlink_trans field to put this transid
+	 * into the file.  When the file is logged we check it and
+	 * don't log the parents if the file is fully on disk.
+	 */
+	mutex_lock(&inode->log_mutex);
+	inode->last_unlink_trans = trans->transid;
+	mutex_unlock(&inode->log_mutex);
+
+	/*
+	 * if this directory was already logged any new
+	 * names for this file/dir will get recorded
+	 */
+	if (dir->logged_trans == trans->transid)
+		return;
+
+	/*
+	 * if the inode we're about to unlink was logged,
+	 * the log will be properly updated for any new names
+	 */
+	if (inode->logged_trans == trans->transid)
+		return;
+
+	/*
+	 * when renaming files across directories, if the directory
+	 * there we're unlinking from gets fsync'd later on, there's
+	 * no way to find the destination directory later and fsync it
+	 * properly.  So, we have to be conservative and force commits
+	 * so the new name gets discovered.
+	 */
+	if (for_rename)
+		goto record;
+
+	/* we can safely do the unlink without any special recording */
+	return;
+
+record:
+	mutex_lock(&dir->log_mutex);
+	dir->last_unlink_trans = trans->transid;
+	mutex_unlock(&dir->log_mutex);
+}
+
+/*
+ * Make sure that if someone attempts to fsync the parent directory of a deleted
+ * snapshot, it ends up triggering a transaction commit. This is to guarantee
+ * that after replaying the log tree of the parent directory's root we will not
+ * see the snapshot anymore and at log replay time we will not see any log tree
+ * corresponding to the deleted snapshot's root, which could lead to replaying
+ * it after replaying the log tree of the parent directory (which would replay
+ * the snapshot delete operation).
+ *
+ * Must be called before the actual snapshot destroy operation (updates to the
+ * parent root and tree of tree roots trees, etc) are done.
+ */
+void btrfs_record_snapshot_destroy(struct btrfs_trans_handle *trans,
+				   struct btrfs_inode *dir)
+{
+	mutex_lock(&dir->log_mutex);
+	dir->last_unlink_trans = trans->transid;
+	mutex_unlock(&dir->log_mutex);
+}
+
+/*
+ * Call this after adding a new name for a file and it will properly
+ * update the log to reflect the new name.
+ *
+ * @ctx can not be NULL when @sync_log is false, and should be NULL when it's
+ * true (because it's not used).
+ *
+ * Return value depends on whether @sync_log is true or false.
+ * When true: returns BTRFS_NEED_TRANS_COMMIT if the transaction needs to be
+ *            committed by the caller, and BTRFS_DONT_NEED_TRANS_COMMIT
+ *            otherwise.
+ * When false: returns BTRFS_DONT_NEED_LOG_SYNC if the caller does not need to
+ *             to sync the log, BTRFS_NEED_LOG_SYNC if it needs to sync the log,
+ *             or BTRFS_NEED_TRANS_COMMIT if the transaction needs to be
+ *             committed (without attempting to sync the log).
+ */
+int btrfs_log_new_name(struct btrfs_trans_handle *trans,
+			struct btrfs_inode *inode, struct btrfs_inode *old_dir,
+			struct dentry *parent,
+			bool sync_log, struct btrfs_log_ctx *ctx)
+{
+	struct btrfs_fs_info *fs_info = trans->fs_info;
+	int ret;
+
+	/*
+	 * this will force the logging code to walk the dentry chain
+	 * up for the file
+	 */
+	if (!S_ISDIR(inode->vfs_inode.i_mode))
+		inode->last_unlink_trans = trans->transid;
+
+	/*
+	 * if this inode hasn't been logged and directory we're renaming it
+	 * from hasn't been logged, we don't need to log it
+	 */
+	if (inode->logged_trans <= fs_info->last_trans_committed &&
+	    (!old_dir || old_dir->logged_trans <= fs_info->last_trans_committed))
+		return sync_log ? BTRFS_DONT_NEED_TRANS_COMMIT :
+			BTRFS_DONT_NEED_LOG_SYNC;
+
+	if (sync_log) {
+		struct btrfs_log_ctx ctx2;
+
+		btrfs_init_log_ctx(&ctx2, &inode->vfs_inode);
+		ret = btrfs_log_inode_parent(trans, inode, parent, 0, LLONG_MAX,
+					     LOG_INODE_EXISTS, &ctx2);
+		if (ret == BTRFS_NO_LOG_SYNC)
+			return BTRFS_DONT_NEED_TRANS_COMMIT;
+		else if (ret)
+			return BTRFS_NEED_TRANS_COMMIT;
+
+		ret = btrfs_sync_log(trans, inode->root, &ctx2);
+		if (ret)
+			return BTRFS_NEED_TRANS_COMMIT;
+		return BTRFS_DONT_NEED_TRANS_COMMIT;
+	}
+
+	ASSERT(ctx);
+	ret = btrfs_log_inode_parent(trans, inode, parent, 0, LLONG_MAX,
+				     LOG_INODE_EXISTS, ctx);
+	if (ret == BTRFS_NO_LOG_SYNC)
+		return BTRFS_DONT_NEED_LOG_SYNC;
+	else if (ret)
+		return BTRFS_NEED_TRANS_COMMIT;
+
+	return BTRFS_NEED_LOG_SYNC;
+}
+