init android origin source code

1 files changed, 3398 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/fs/btrfs/tree-log.c b/ANDROID_3.4.5/fs/btrfs/tree-log.c
new file mode 100644
index 00000000..dce89da9
--- /dev/null
+++ b/ANDROID_3.4.5/fs/btrfs/tree-log.c
@@ -0,0 +1,3398 @@
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include "ctree.h"
+#include "transaction.h"
+#include "disk-io.h"
+#include "locking.h"
+#include "print-tree.h"
+#include "compat.h"
+#include "tree-log.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
+
+/*
+ * 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_ALL 2
+
+static int btrfs_log_inode(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root, struct inode *inode,
+			     int inode_only);
+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)
+{
+	int ret;
+	int err = 0;
+
+	mutex_lock(&root->log_mutex);
+	if (root->log_root) {
+		if (!root->log_start_pid) {
+			root->log_start_pid = current->pid;
+			root->log_multiple_pids = false;
+		} else if (root->log_start_pid != current->pid) {
+			root->log_multiple_pids = true;
+		}
+
+		root->log_batch++;
+		atomic_inc(&root->log_writers);
+		mutex_unlock(&root->log_mutex);
+		return 0;
+	}
+	root->log_multiple_pids = false;
+	root->log_start_pid = current->pid;
+	mutex_lock(&root->fs_info->tree_log_mutex);
+	if (!root->fs_info->log_root_tree) {
+		ret = btrfs_init_log_root_tree(trans, root->fs_info);
+		if (ret)
+			err = ret;
+	}
+	if (err == 0 && !root->log_root) {
+		ret = btrfs_add_log_tree(trans, root);
+		if (ret)
+			err = ret;
+	}
+	mutex_unlock(&root->fs_info->tree_log_mutex);
+	root->log_batch++;
+	atomic_inc(&root->log_writers);
+	mutex_unlock(&root->log_mutex);
+	return err;
+}
+
+/*
+ * 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)) {
+		smp_mb();
+		if (waitqueue_active(&root->log_writer_wait))
+			wake_up(&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;
+
+	/* 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);
+};
+
+/*
+ * 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)
+{
+	if (wc->pin)
+		btrfs_pin_extent_for_log_replay(wc->trans,
+						log->fs_info->extent_root,
+						eb->start, eb->len);
+
+	if (btrfs_buffer_uptodate(eb, gen, 0)) {
+		if (wc->write)
+			btrfs_write_tree_block(eb);
+		if (wc->wait)
+			btrfs_wait_tree_block_writeback(eb);
+	}
+	return 0;
+}
+
+/*
+ * 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)
+{
+	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;
+
+	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) {
+		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;
+		}
+
+	}
+insert:
+	btrfs_release_path(path);
+	/* try to insert the key into the destination tree */
+	ret = btrfs_insert_empty_item(trans, root, path,
+				      key, item_size);
+
+	/* make sure any existing item is the correct size */
+	if (ret == -EEXIST) {
+		u32 found_size;
+		found_size = btrfs_item_size_nr(path->nodes[0],
+						path->slots[0]);
+		if (found_size > item_size)
+			btrfs_truncate_item(trans, root, path, item_size, 1);
+		else if (found_size < item_size)
+			btrfs_extend_item(trans, root, 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)
+			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;
+	} else if (is_bad_inode(inode)) {
+		iput(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)
+{
+	int found_type;
+	u64 mask = root->sectorsize - 1;
+	u64 extent_end;
+	u64 alloc_hint;
+	u64 start = key->offset;
+	u64 saved_nbytes;
+	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)
+		extent_end = start + btrfs_file_extent_num_bytes(eb, item);
+	else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+		size = btrfs_file_extent_inline_len(eb, item);
+		extent_end = (start + size + mask) & ~mask;
+	} 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(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);
+
+	saved_nbytes = inode_get_bytes(inode);
+	/* drop any overlapping extents */
+	ret = btrfs_drop_extents(trans, inode, start, extent_end,
+				 &alloc_hint, 1);
+	BUG_ON(ret);
+
+	if (found_type == BTRFS_FILE_EXTENT_REG ||
+	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		u64 offset;
+		unsigned long dest_offset;
+		struct btrfs_key ins;
+
+		ret = btrfs_insert_empty_item(trans, root, path, key,
+					      sizeof(*item));
+		BUG_ON(ret);
+		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);
+
+		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_extent(root, 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, 0);
+				BUG_ON(ret);
+			} else {
+				/*
+				 * insert the extent pointer in the extent
+				 * allocation tree
+				 */
+				ret = btrfs_alloc_logged_file_extent(trans,
+						root, root->root_key.objectid,
+						key->objectid, offset, &ins);
+				BUG_ON(ret);
+			}
+			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);
+			BUG_ON(ret);
+			while (!list_empty(&ordered_sums)) {
+				struct btrfs_ordered_sum *sums;
+				sums = list_entry(ordered_sums.next,
+						struct btrfs_ordered_sum,
+						list);
+				ret = btrfs_csum_file_blocks(trans,
+						root->fs_info->csum_root,
+						sums);
+				BUG_ON(ret);
+				list_del(&sums->list);
+				kfree(sums);
+			}
+		} 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);
+		BUG_ON(ret);
+	}
+
+	inode_set_bytes(inode, saved_nbytes);
+	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 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) {
+		kfree(name);
+		return -EIO;
+	}
+
+	ret = link_to_fixup_dir(trans, root, path, location.objectid);
+	BUG_ON(ret);
+
+	ret = btrfs_unlink_inode(trans, root, dir, inode, name, name_len);
+	BUG_ON(ret);
+	kfree(name);
+
+	iput(inode);
+
+	btrfs_run_delayed_items(trans, root);
+	return ret;
+}
+
+/*
+ * helper function to 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
+ */
+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 match = 0;
+
+	di = btrfs_lookup_dir_index_item(NULL, root, path, dirid,
+					 index, name, name_len, 0);
+	if (di && !IS_ERR(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 (di && !IS_ERR(di)) {
+		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
+		if (location.objectid != objectid)
+			goto out;
+	} else
+		goto out;
+	match = 1;
+out:
+	btrfs_release_path(path);
+	return match;
+}
+
+/*
+ * 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,
+				   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;
+
+	item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
+	ptr = btrfs_item_ptr_offset(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;
+}
+
+
+/*
+ * 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 btrfs_inode_ref *ref;
+	struct btrfs_dir_item *di;
+	struct inode *dir;
+	struct inode *inode;
+	unsigned long ref_ptr;
+	unsigned long ref_end;
+	char *name;
+	int namelen;
+	int ret;
+	int search_done = 0;
+
+	/*
+	 * 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, key->offset);
+	if (!dir)
+		return -ENOENT;
+
+	inode = read_one_inode(root, key->objectid);
+	if (!inode) {
+		iput(dir);
+		return -EIO;
+	}
+
+	ref_ptr = btrfs_item_ptr_offset(eb, slot);
+	ref_end = ref_ptr + btrfs_item_size_nr(eb, slot);
+
+again:
+	ref = (struct btrfs_inode_ref *)ref_ptr;
+
+	namelen = btrfs_inode_ref_name_len(eb, ref);
+	name = kmalloc(namelen, GFP_NOFS);
+	BUG_ON(!name);
+
+	read_extent_buffer(eb, name, (unsigned long)(ref + 1), namelen);
+
+	/* if we already have a perfect match, we're done */
+	if (inode_in_dir(root, path, btrfs_ino(dir), btrfs_ino(inode),
+			 btrfs_inode_ref_index(eb, ref),
+			 name, namelen)) {
+		goto out;
+	}
+
+	/*
+	 * 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)
+		goto insert;
+
+	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+	if (ret == 0) {
+		char *victim_name;
+		int victim_name_len;
+		struct btrfs_inode_ref *victim_ref;
+		unsigned long ptr;
+		unsigned long ptr_end;
+		struct extent_buffer *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 (key->objectid == key->offset)
+			goto out_nowrite;
+
+		/* 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);
+			BUG_ON(!victim_name);
+
+			read_extent_buffer(leaf, victim_name,
+					   (unsigned long)(victim_ref + 1),
+					   victim_name_len);
+
+			if (!backref_in_log(log, key, victim_name,
+					    victim_name_len)) {
+				btrfs_inc_nlink(inode);
+				btrfs_release_path(path);
+
+				ret = btrfs_unlink_inode(trans, root, dir,
+							 inode, victim_name,
+							 victim_name_len);
+				btrfs_run_delayed_items(trans, root);
+			}
+			kfree(victim_name);
+			ptr = (unsigned long)(victim_ref + 1) + victim_name_len;
+		}
+		BUG_ON(ret);
+
+		/*
+		 * NOTE: we have searched root tree and checked the
+		 * coresponding ref, it does not need to check again.
+		 */
+		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),
+					 btrfs_inode_ref_index(eb, ref),
+					 name, namelen, 0);
+	if (di && !IS_ERR(di)) {
+		ret = drop_one_dir_item(trans, root, path, dir, di);
+		BUG_ON(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 (di && !IS_ERR(di)) {
+		ret = drop_one_dir_item(trans, root, path, dir, di);
+		BUG_ON(ret);
+	}
+	btrfs_release_path(path);
+
+insert:
+	/* insert our name */
+	ret = btrfs_add_link(trans, dir, inode, name, namelen, 0,
+			     btrfs_inode_ref_index(eb, ref));
+	BUG_ON(ret);
+
+	btrfs_update_inode(trans, root, inode);
+
+out:
+	ref_ptr = (unsigned long)(ref + 1) + namelen;
+	kfree(name);
+	if (ref_ptr < ref_end)
+		goto again;
+
+	/* finally write the back reference in the inode */
+	ret = overwrite_item(trans, root, path, eb, slot, key);
+	BUG_ON(ret);
+
+out_nowrite:
+	btrfs_release_path(path);
+	iput(dir);
+	iput(inode);
+	return 0;
+}
+
+static int insert_orphan_item(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root, u64 offset)
+{
+	int ret;
+	ret = btrfs_find_orphan_item(root, offset);
+	if (ret > 0)
+		ret = btrfs_insert_orphan_item(trans, root, offset);
+	return ret;
+}
+
+
+/*
+ * 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;
+	struct btrfs_key key;
+	u64 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;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	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]--;
+		}
+		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;
+		key.offset--;
+		btrfs_release_path(path);
+	}
+	btrfs_release_path(path);
+	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);
+			BUG_ON(ret);
+		}
+		ret = insert_orphan_item(trans, root, ino);
+		BUG_ON(ret);
+	}
+	btrfs_free_path(path);
+
+	return 0;
+}
+
+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) {
+			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)
+			goto out;
+
+		btrfs_release_path(path);
+		inode = read_one_inode(root, key.offset);
+		if (!inode)
+			return -EIO;
+
+		ret = fixup_inode_link_count(trans, root, inode);
+		BUG_ON(ret);
+
+		iput(inode);
+
+		/*
+		 * fixup on a directory may create new entries,
+		 * make sure we always look for the highset possible
+		 * offset
+		 */
+		key.offset = (u64)-1;
+	}
+	ret = 0;
+out:
+	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;
+	btrfs_set_key_type(&key, BTRFS_ORPHAN_ITEM_KEY);
+	key.offset = objectid;
+
+	ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
+
+	btrfs_release_path(path);
+	if (ret == 0) {
+		btrfs_inc_nlink(inode);
+		btrfs_update_inode(trans, root, inode);
+	} else if (ret == -EEXIST) {
+		ret = 0;
+	} else {
+		BUG();
+	}
+	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,
+				    struct btrfs_path *path,
+				    u64 dirid, u64 index,
+				    char *name, int name_len, u8 type,
+				    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, dir, inode, name, name_len, 1, index);
+
+	/* FIXME, put inode into FIXUP list */
+
+	iput(inode);
+	iput(dir);
+	return ret;
+}
+
+/*
+ * 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.
+ */
+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;
+	int exists;
+	int ret;
+
+	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)
+		return -ENOMEM;
+
+	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);
+	exists = btrfs_lookup_inode(trans, root, path, &log_key, 0);
+	if (exists == 0)
+		exists = 1;
+	else
+		exists = 0;
+	btrfs_release_path(path);
+
+	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 {
+		BUG();
+	}
+	if (IS_ERR_OR_NULL(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) {
+		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, dir, dst_di);
+	BUG_ON(ret);
+
+	if (key->type == BTRFS_DIR_INDEX_KEY)
+		goto insert;
+out:
+	btrfs_release_path(path);
+	kfree(name);
+	iput(dir);
+	return 0;
+
+insert:
+	btrfs_release_path(path);
+	ret = insert_one_name(trans, root, path, key->objectid, key->offset,
+			      name, name_len, log_type, &log_key);
+
+	BUG_ON(ret && ret != -ENOENT);
+	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;
+	u32 item_size = btrfs_item_size_nr(eb, slot);
+	struct btrfs_dir_item *di;
+	int name_len;
+	unsigned long ptr;
+	unsigned long ptr_end;
+
+	ptr = btrfs_item_ptr_offset(eb, slot);
+	ptr_end = ptr + item_size;
+	while (ptr < ptr_end) {
+		di = (struct btrfs_dir_item *)ptr;
+		if (verify_dir_item(root, eb, di))
+			return -EIO;
+		name_len = btrfs_dir_name_len(eb, di);
+		ret = replay_one_name(trans, root, path, eb, di, key);
+		BUG_ON(ret);
+		ptr = (unsigned long)(di + 1);
+		ptr += name_len;
+	}
+	return 0;
+}
+
+/*
+ * 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]);
+	if (path->slots[0] >= nritems) {
+		ret = btrfs_next_leaf(root, path);
+		if (ret)
+			goto out;
+	} else {
+		path->slots[0]++;
+	}
+
+	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;
+		if (verify_dir_item(root, eb, di)) {
+			ret = -EIO;
+			goto out;
+		}
+
+		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 (IS_ERR_OR_NULL(log_di)) {
+			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);
+			BUG_ON(ret);
+			btrfs_inc_nlink(inode);
+			ret = btrfs_unlink_inode(trans, root, dir, inode,
+						 name, name_len);
+			BUG_ON(ret);
+
+			btrfs_run_delayed_items(trans, root);
+
+			kfree(name);
+			iput(inode);
+
+			/* 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;
+		}
+		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;
+}
+
+/*
+ * 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)
+				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)
+					break;
+			}
+			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);
+			BUG_ON(ret);
+			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 nritems;
+	struct btrfs_path *path;
+	struct btrfs_root *root = wc->replay_dest;
+	struct btrfs_key key;
+	int level;
+	int i;
+	int ret;
+
+	btrfs_read_buffer(eb, gen);
+
+	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);
+			mode = btrfs_inode_mode(eb, inode_item);
+			if (S_ISDIR(mode)) {
+				ret = replay_dir_deletes(wc->trans,
+					 root, log, path, key.objectid, 0);
+				BUG_ON(ret);
+			}
+			ret = overwrite_item(wc->trans, root, path,
+					     eb, i, &key);
+			BUG_ON(ret);
+
+			/* for regular files, make sure corresponding
+			 * orhpan item exist. extents past the new EOF
+			 * will be truncated later by orphan cleanup.
+			 */
+			if (S_ISREG(mode)) {
+				ret = insert_orphan_item(wc->trans, root,
+							 key.objectid);
+				BUG_ON(ret);
+			}
+
+			ret = link_to_fixup_dir(wc->trans, root,
+						path, key.objectid);
+			BUG_ON(ret);
+		}
+		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);
+			BUG_ON(ret);
+		} else if (key.type == BTRFS_INODE_REF_KEY) {
+			ret = add_inode_ref(wc->trans, root, log, path,
+					    eb, i, &key);
+			BUG_ON(ret && ret != -ENOENT);
+		} else if (key.type == BTRFS_EXTENT_DATA_KEY) {
+			ret = replay_one_extent(wc->trans, root, path,
+						eb, i, &key);
+			BUG_ON(ret);
+		} else if (key.type == BTRFS_DIR_ITEM_KEY ||
+			   key.type == BTRFS_DIR_INDEX_KEY) {
+			ret = replay_one_dir_item(wc->trans, root, path,
+						  eb, i, &key);
+			BUG_ON(ret);
+		}
+	}
+	btrfs_free_path(path);
+	return 0;
+}
+
+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)
+{
+	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) {
+		WARN_ON(*level < 0);
+		WARN_ON(*level >= BTRFS_MAX_LEVEL);
+		cur = path->nodes[*level];
+
+		if (btrfs_header_level(cur) != *level)
+			WARN_ON(1);
+
+		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]);
+		blocksize = btrfs_level_size(root, *level - 1);
+
+		parent = path->nodes[*level];
+		root_owner = btrfs_header_owner(parent);
+
+		next = btrfs_find_create_tree_block(root, bytenr, blocksize);
+		if (!next)
+			return -ENOMEM;
+
+		if (*level == 1) {
+			ret = wc->process_func(root, next, wc, ptr_gen);
+			if (ret)
+				return ret;
+
+			path->slots[*level]++;
+			if (wc->free) {
+				btrfs_read_buffer(next, ptr_gen);
+
+				btrfs_tree_lock(next);
+				btrfs_set_lock_blocking(next);
+				clean_tree_block(trans, root, next);
+				btrfs_wait_tree_block_writeback(next);
+				btrfs_tree_unlock(next);
+
+				WARN_ON(root_owner !=
+					BTRFS_TREE_LOG_OBJECTID);
+				ret = btrfs_free_and_pin_reserved_extent(root,
+							 bytenr, blocksize);
+				BUG_ON(ret); /* -ENOMEM or logic errors */
+			}
+			free_extent_buffer(next);
+			continue;
+		}
+		btrfs_read_buffer(next, ptr_gen);
+
+		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)
+{
+	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]));
+			if (ret)
+				return ret;
+
+			if (wc->free) {
+				struct extent_buffer *next;
+
+				next = path->nodes[*level];
+
+				btrfs_tree_lock(next);
+				btrfs_set_lock_blocking(next);
+				clean_tree_block(trans, root, next);
+				btrfs_wait_tree_block_writeback(next);
+				btrfs_tree_unlock(next);
+
+				WARN_ON(root_owner != BTRFS_TREE_LOG_OBJECTID);
+				ret = btrfs_free_and_pin_reserved_extent(root,
+						path->nodes[*level]->start,
+						path->nodes[*level]->len);
+				BUG_ON(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)
+{
+	int ret = 0;
+	int wret;
+	int level;
+	struct btrfs_path *path;
+	int i;
+	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]));
+		if (ret)
+			goto out;
+		if (wc->free) {
+			struct extent_buffer *next;
+
+			next = path->nodes[orig_level];
+
+			btrfs_tree_lock(next);
+			btrfs_set_lock_blocking(next);
+			clean_tree_block(trans, log, next);
+			btrfs_wait_tree_block_writeback(next);
+			btrfs_tree_unlock(next);
+
+			WARN_ON(log->root_key.objectid !=
+				BTRFS_TREE_LOG_OBJECTID);
+			ret = btrfs_free_and_pin_reserved_extent(log, next->start,
+							 next->len);
+			BUG_ON(ret); /* -ENOMEM or logic errors */
+		}
+	}
+
+out:
+	for (i = 0; i <= orig_level; i++) {
+		if (path->nodes[i]) {
+			free_extent_buffer(path->nodes[i]);
+			path->nodes[i] = NULL;
+		}
+	}
+	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)
+{
+	int ret;
+
+	if (log->log_transid == 1) {
+		/* insert root item on the first sync */
+		ret = btrfs_insert_root(trans, log->fs_info->log_root_tree,
+				&log->root_key, &log->root_item);
+	} else {
+		ret = btrfs_update_root(trans, log->fs_info->log_root_tree,
+				&log->root_key, &log->root_item);
+	}
+	return ret;
+}
+
+static int wait_log_commit(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root, unsigned long 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
+	 */
+	do {
+		prepare_to_wait(&root->log_commit_wait[index],
+				&wait, TASK_UNINTERRUPTIBLE);
+		mutex_unlock(&root->log_mutex);
+
+		if (root->fs_info->last_trans_log_full_commit !=
+		    trans->transid && root->log_transid < transid + 2 &&
+		    atomic_read(&root->log_commit[index]))
+			schedule();
+
+		finish_wait(&root->log_commit_wait[index], &wait);
+		mutex_lock(&root->log_mutex);
+	} while (root->fs_info->last_trans_log_full_commit !=
+		 trans->transid && root->log_transid < transid + 2 &&
+		 atomic_read(&root->log_commit[index]));
+	return 0;
+}
+
+static void wait_for_writer(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root)
+{
+	DEFINE_WAIT(wait);
+	while (root->fs_info->last_trans_log_full_commit !=
+	       trans->transid && atomic_read(&root->log_writers)) {
+		prepare_to_wait(&root->log_writer_wait,
+				&wait, TASK_UNINTERRUPTIBLE);
+		mutex_unlock(&root->log_mutex);
+		if (root->fs_info->last_trans_log_full_commit !=
+		    trans->transid && atomic_read(&root->log_writers))
+			schedule();
+		mutex_lock(&root->log_mutex);
+		finish_wait(&root->log_writer_wait, &wait);
+	}
+}
+
+/*
+ * 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)
+{
+	int index1;
+	int index2;
+	int mark;
+	int ret;
+	struct btrfs_root *log = root->log_root;
+	struct btrfs_root *log_root_tree = root->fs_info->log_root_tree;
+	unsigned long log_transid = 0;
+
+	mutex_lock(&root->log_mutex);
+	index1 = root->log_transid % 2;
+	if (atomic_read(&root->log_commit[index1])) {
+		wait_log_commit(trans, root, root->log_transid);
+		mutex_unlock(&root->log_mutex);
+		return 0;
+	}
+	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(trans, root, root->log_transid - 1);
+	while (1) {
+		unsigned long batch = root->log_batch;
+		/* when we're on an ssd, just kick the log commit out */
+		if (!btrfs_test_opt(root, SSD) && root->log_multiple_pids) {
+			mutex_unlock(&root->log_mutex);
+			schedule_timeout_uninterruptible(1);
+			mutex_lock(&root->log_mutex);
+		}
+		wait_for_writer(trans, root);
+		if (batch == root->log_batch)
+			break;
+	}
+
+	/* bail out if we need to do a full commit */
+	if (root->fs_info->last_trans_log_full_commit == trans->transid) {
+		ret = -EAGAIN;
+		mutex_unlock(&root->log_mutex);
+		goto out;
+	}
+
+	log_transid = root->log_transid;
+	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.
+	 */
+	ret = btrfs_write_marked_extents(log, &log->dirty_log_pages, mark);
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		mutex_unlock(&root->log_mutex);
+		goto out;
+	}
+
+	btrfs_set_root_node(&log->root_item, log->node);
+
+	root->log_batch = 0;
+	root->log_transid++;
+	log->log_transid = root->log_transid;
+	root->log_start_pid = 0;
+	smp_mb();
+	/*
+	 * 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);
+
+	mutex_lock(&log_root_tree->log_mutex);
+	log_root_tree->log_batch++;
+	atomic_inc(&log_root_tree->log_writers);
+	mutex_unlock(&log_root_tree->log_mutex);
+
+	ret = update_log_root(trans, log);
+
+	mutex_lock(&log_root_tree->log_mutex);
+	if (atomic_dec_and_test(&log_root_tree->log_writers)) {
+		smp_mb();
+		if (waitqueue_active(&log_root_tree->log_writer_wait))
+			wake_up(&log_root_tree->log_writer_wait);
+	}
+
+	if (ret) {
+		if (ret != -ENOSPC) {
+			btrfs_abort_transaction(trans, root, ret);
+			mutex_unlock(&log_root_tree->log_mutex);
+			goto out;
+		}
+		root->fs_info->last_trans_log_full_commit = trans->transid;
+		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+		mutex_unlock(&log_root_tree->log_mutex);
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	index2 = log_root_tree->log_transid % 2;
+	if (atomic_read(&log_root_tree->log_commit[index2])) {
+		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+		wait_log_commit(trans, log_root_tree,
+				log_root_tree->log_transid);
+		mutex_unlock(&log_root_tree->log_mutex);
+		ret = 0;
+		goto out;
+	}
+	atomic_set(&log_root_tree->log_commit[index2], 1);
+
+	if (atomic_read(&log_root_tree->log_commit[(index2 + 1) % 2])) {
+		wait_log_commit(trans, log_root_tree,
+				log_root_tree->log_transid - 1);
+	}
+
+	wait_for_writer(trans, log_root_tree);
+
+	/*
+	 * now that we've moved on to the tree of log tree roots,
+	 * check the full commit flag again
+	 */
+	if (root->fs_info->last_trans_log_full_commit == trans->transid) {
+		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+		mutex_unlock(&log_root_tree->log_mutex);
+		ret = -EAGAIN;
+		goto out_wake_log_root;
+	}
+
+	ret = btrfs_write_and_wait_marked_extents(log_root_tree,
+				&log_root_tree->dirty_log_pages,
+				EXTENT_DIRTY | EXTENT_NEW);
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		mutex_unlock(&log_root_tree->log_mutex);
+		goto out_wake_log_root;
+	}
+	btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+
+	btrfs_set_super_log_root(root->fs_info->super_for_commit,
+				log_root_tree->node->start);
+	btrfs_set_super_log_root_level(root->fs_info->super_for_commit,
+				btrfs_header_level(log_root_tree->node));
+
+	log_root_tree->log_batch = 0;
+	log_root_tree->log_transid++;
+	smp_mb();
+
+	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.
+	 */
+	btrfs_scrub_pause_super(root);
+	write_ctree_super(trans, root->fs_info->tree_root, 1);
+	btrfs_scrub_continue_super(root);
+	ret = 0;
+
+	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:
+	atomic_set(&log_root_tree->log_commit[index2], 0);
+	smp_mb();
+	if (waitqueue_active(&log_root_tree->log_commit_wait[index2]))
+		wake_up(&log_root_tree->log_commit_wait[index2]);
+out:
+	atomic_set(&root->log_commit[index1], 0);
+	smp_mb();
+	if (waitqueue_active(&root->log_commit_wait[index1]))
+		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);
+	BUG_ON(ret);
+
+	while (1) {
+		ret = find_first_extent_bit(&log->dirty_log_pages,
+				0, &start, &end, EXTENT_DIRTY | EXTENT_NEW);
+		if (ret)
+			break;
+
+		clear_extent_bits(&log->dirty_log_pages, start, end,
+				  EXTENT_DIRTY | EXTENT_NEW, GFP_NOFS);
+	}
+
+	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;
+}
+
+/*
+ * 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 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 (BTRFS_I(dir)->logged_trans < trans->transid)
+		return 0;
+
+	ret = join_running_log_trans(root);
+	if (ret)
+		return 0;
+
+	mutex_lock(&BTRFS_I(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;
+		BUG_ON(ret);
+	}
+	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;
+		BUG_ON(ret);
+	}
+
+	/* 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(&BTRFS_I(dir)->log_mutex);
+	if (ret == -ENOSPC) {
+		root->fs_info->last_trans_log_full_commit = trans->transid;
+		ret = 0;
+	} else if (ret < 0)
+		btrfs_abort_transaction(trans, root, ret);
+
+	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 inode *inode, u64 dirid)
+{
+	struct btrfs_root *log;
+	u64 index;
+	int ret;
+
+	if (BTRFS_I(inode)->logged_trans < trans->transid)
+		return 0;
+
+	ret = join_running_log_trans(root);
+	if (ret)
+		return 0;
+	log = root->log_root;
+	mutex_lock(&BTRFS_I(inode)->log_mutex);
+
+	ret = btrfs_del_inode_ref(trans, log, name, name_len, btrfs_ino(inode),
+				  dirid, &index);
+	mutex_unlock(&BTRFS_I(inode)->log_mutex);
+	if (ret == -ENOSPC) {
+		root->fs_info->last_trans_log_full_commit = trans->transid;
+		ret = 0;
+	} else if (ret < 0 && ret != -ENOENT)
+		btrfs_abort_transaction(trans, root, 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 inode *inode,
+			  struct btrfs_path *path,
+			  struct btrfs_path *dst_path, int key_type,
+			  u64 min_offset, u64 *last_offset_ret)
+{
+	struct btrfs_key min_key;
+	struct btrfs_key max_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;
+	max_key.objectid = ino;
+	max_key.offset = (u64)-1;
+	max_key.type = key_type;
+
+	min_key.objectid = ino;
+	min_key.type = key_type;
+	min_key.offset = min_offset;
+
+	path->keep_locks = 1;
+
+	ret = btrfs_search_forward(root, &min_key, &max_key,
+				   path, 0, 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 */
+	ret = btrfs_search_slot(NULL, root, &min_key, path, 0, 0);
+	if (ret != 0) {
+		WARN_ON(1);
+		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++) {
+			btrfs_item_key_to_cpu(src, &min_key, i);
+
+			if (min_key.objectid != ino || min_key.type != key_type)
+				goto done;
+			ret = overwrite_item(trans, log, dst_path, src, i,
+					     &min_key);
+			if (ret) {
+				err = ret;
+				goto done;
+			}
+		}
+		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 == 1) {
+			last_offset = (u64)-1;
+			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 inode *inode,
+			  struct btrfs_path *path,
+			  struct btrfs_path *dst_path)
+{
+	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, 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;
+
+	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);
+		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;
+
+		ret = btrfs_del_item(trans, log, path);
+		if (ret)
+			break;
+		btrfs_release_path(path);
+	}
+	btrfs_release_path(path);
+	return ret;
+}
+
+static noinline int copy_items(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *log,
+			       struct btrfs_path *dst_path,
+			       struct extent_buffer *src,
+			       int start_slot, int nr, int inode_only)
+{
+	unsigned long src_offset;
+	unsigned long dst_offset;
+	struct btrfs_file_extent_item *extent;
+	struct btrfs_inode_item *inode_item;
+	int ret;
+	struct btrfs_key *ins_keys;
+	u32 *ins_sizes;
+	char *ins_data;
+	int i;
+	struct list_head ordered_sums;
+
+	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);
+
+		copy_extent_buffer(dst_path->nodes[0], src, dst_offset,
+				   src_offset, ins_sizes[i]);
+
+		if (inode_only == LOG_INODE_EXISTS &&
+		    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);
+			btrfs_set_inode_size(dst_path->nodes[0], inode_item, 0);
+
+			/* 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_inode_generation(dst_path->nodes[0],
+						   inode_item, 0);
+		}
+		/* take a reference on file data extents so that truncates
+		 * or deletes of this inode don't have to relog the inode
+		 * again
+		 */
+		if (btrfs_key_type(ins_keys + i) == BTRFS_EXTENT_DATA_KEY) {
+			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 ||
+			    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+				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(
+						log->fs_info->csum_root,
+						ds + cs, ds + cs + cl - 1,
+						&ordered_sums, 0);
+				BUG_ON(ret);
+			}
+		}
+	}
+
+	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.
+	 */
+	ret = 0;
+	while (!list_empty(&ordered_sums)) {
+		struct btrfs_ordered_sum *sums = list_entry(ordered_sums.next,
+						   struct btrfs_ordered_sum,
+						   list);
+		if (!ret)
+			ret = btrfs_csum_file_blocks(trans, log, sums);
+		list_del(&sums->list);
+		kfree(sums);
+	}
+	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 inode *inode,
+			     int inode_only)
+{
+	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;
+	struct extent_buffer *src = NULL;
+	int err = 0;
+	int ret;
+	int nritems;
+	int ins_start_slot = 0;
+	int ins_nr;
+	u64 ino = btrfs_ino(inode);
+
+	log = root->log_root;
+
+	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->i_mode))
+	    inode_only = LOG_INODE_ALL;
+
+	if (inode_only == LOG_INODE_EXISTS || S_ISDIR(inode->i_mode))
+		max_key.type = BTRFS_XATTR_ITEM_KEY;
+	else
+		max_key.type = (u8)-1;
+	max_key.offset = (u64)-1;
+
+	ret = btrfs_commit_inode_delayed_items(trans, inode);
+	if (ret) {
+		btrfs_free_path(path);
+		btrfs_free_path(dst_path);
+		return ret;
+	}
+
+	mutex_lock(&BTRFS_I(inode)->log_mutex);
+
+	/*
+	 * a brute force approach to making sure we get the most uptodate
+	 * copies of everything.
+	 */
+	if (S_ISDIR(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 {
+		ret = btrfs_truncate_inode_items(trans, log, inode, 0, 0);
+	}
+	if (ret) {
+		err = ret;
+		goto out_unlock;
+	}
+	path->keep_locks = 1;
+
+	while (1) {
+		ins_nr = 0;
+		ret = btrfs_search_forward(root, &min_key, &max_key,
+					   path, 0, trans->transid);
+		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;
+
+		src = path->nodes[0];
+		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, log, dst_path, src, ins_start_slot,
+				 ins_nr, inode_only);
+		if (ret) {
+			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, log, dst_path, src,
+					 ins_start_slot,
+					 ins_nr, inode_only);
+			if (ret) {
+				err = ret;
+				goto out_unlock;
+			}
+			ins_nr = 0;
+		}
+		btrfs_release_path(path);
+
+		if (min_key.offset < (u64)-1)
+			min_key.offset++;
+		else if (min_key.type < (u8)-1)
+			min_key.type++;
+		else if (min_key.objectid < (u64)-1)
+			min_key.objectid++;
+		else
+			break;
+	}
+	if (ins_nr) {
+		ret = copy_items(trans, log, dst_path, src,
+				 ins_start_slot,
+				 ins_nr, inode_only);
+		if (ret) {
+			err = ret;
+			goto out_unlock;
+		}
+		ins_nr = 0;
+	}
+	WARN_ON(ins_nr);
+	if (inode_only == LOG_INODE_ALL && S_ISDIR(inode->i_mode)) {
+		btrfs_release_path(path);
+		btrfs_release_path(dst_path);
+		ret = log_directory_changes(trans, root, inode, path, dst_path);
+		if (ret) {
+			err = ret;
+			goto out_unlock;
+		}
+	}
+	BTRFS_I(inode)->logged_trans = trans->transid;
+out_unlock:
+	mutex_unlock(&BTRFS_I(inode)->log_mutex);
+
+	btrfs_free_path(path);
+	btrfs_free_path(dst_path);
+	return err;
+}
+
+/*
+ * 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 inode *inode,
+					       struct dentry *parent,
+					       struct super_block *sb,
+					       u64 last_committed)
+{
+	int ret = 0;
+	struct btrfs_root *root;
+	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->i_mode) &&
+	    BTRFS_I(inode)->generation <= last_committed &&
+	    BTRFS_I(inode)->last_unlink_trans <= last_committed)
+			goto out;
+
+	if (!S_ISDIR(inode->i_mode)) {
+		if (!parent || !parent->d_inode || sb != parent->d_inode->i_sb)
+			goto out;
+		inode = parent->d_inode;
+	}
+
+	while (1) {
+		BTRFS_I(inode)->logged_trans = trans->transid;
+		smp_mb();
+
+		if (BTRFS_I(inode)->last_unlink_trans > last_committed) {
+			root = BTRFS_I(inode)->root;
+
+			/*
+			 * make sure any commits to the log are forced
+			 * to be full commits
+			 */
+			root->fs_info->last_trans_log_full_commit =
+				trans->transid;
+			ret = 1;
+			break;
+		}
+
+		if (!parent || !parent->d_inode || sb != parent->d_inode->i_sb)
+			break;
+
+		if (IS_ROOT(parent))
+			break;
+
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
+		inode = parent->d_inode;
+
+	}
+	dput(old_parent);
+out:
+	return ret;
+}
+
+static int inode_in_log(struct btrfs_trans_handle *trans,
+		 struct inode *inode)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int ret = 0;
+
+	mutex_lock(&root->log_mutex);
+	if (BTRFS_I(inode)->logged_trans == trans->transid &&
+	    BTRFS_I(inode)->last_sub_trans <= root->last_log_commit)
+		ret = 1;
+	mutex_unlock(&root->log_mutex);
+	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
+ */
+int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
+		    struct btrfs_root *root, struct inode *inode,
+		    struct dentry *parent, int exists_only)
+{
+	int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL;
+	struct super_block *sb;
+	struct dentry *old_parent = NULL;
+	int ret = 0;
+	u64 last_committed = root->fs_info->last_trans_committed;
+
+	sb = inode->i_sb;
+
+	if (btrfs_test_opt(root, NOTREELOG)) {
+		ret = 1;
+		goto end_no_trans;
+	}
+
+	if (root->fs_info->last_trans_log_full_commit >
+	    root->fs_info->last_trans_committed) {
+		ret = 1;
+		goto end_no_trans;
+	}
+
+	if (root != BTRFS_I(inode)->root ||
+	    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;
+
+	if (inode_in_log(trans, inode)) {
+		ret = BTRFS_NO_LOG_SYNC;
+		goto end_no_trans;
+	}
+
+	ret = start_log_trans(trans, root);
+	if (ret)
+		goto end_trans;
+
+	ret = btrfs_log_inode(trans, root, inode, inode_only);
+	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->i_mode) &&
+	    BTRFS_I(inode)->generation <= last_committed &&
+	    BTRFS_I(inode)->last_unlink_trans <= last_committed) {
+		ret = 0;
+		goto end_trans;
+	}
+
+	inode_only = LOG_INODE_EXISTS;
+	while (1) {
+		if (!parent || !parent->d_inode || sb != parent->d_inode->i_sb)
+			break;
+
+		inode = parent->d_inode;
+		if (root != BTRFS_I(inode)->root)
+			break;
+
+		if (BTRFS_I(inode)->generation >
+		    root->fs_info->last_trans_committed) {
+			ret = btrfs_log_inode(trans, root, inode, inode_only);
+			if (ret)
+				goto end_trans;
+		}
+		if (IS_ROOT(parent))
+			break;
+
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
+	}
+	ret = 0;
+end_trans:
+	dput(old_parent);
+	if (ret < 0) {
+		BUG_ON(ret != -ENOSPC);
+		root->fs_info->last_trans_log_full_commit = trans->transid;
+		ret = 1;
+	}
+	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 btrfs_root *root, struct dentry *dentry)
+{
+	struct dentry *parent = dget_parent(dentry);
+	int ret;
+
+	ret = btrfs_log_inode_parent(trans, root, dentry->d_inode, parent, 0);
+	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;
+
+	fs_info->log_root_recovering = 1;
+
+	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_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;
+	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+
+	while (1) {
+		ret = btrfs_search_slot(NULL, log_root_tree, &key, path, 0, 0);
+
+		if (ret < 0) {
+			btrfs_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_no_radix(log_root_tree,
+						  &found_key);
+		if (IS_ERR(log)) {
+			ret = PTR_ERR(log);
+			btrfs_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);
+			btrfs_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);
+		BUG_ON(ret);
+
+		if (wc.stage == LOG_WALK_REPLAY_ALL) {
+			ret = fixup_inode_link_counts(trans, wc.replay_dest,
+						      path);
+			BUG_ON(ret);
+		}
+
+		key.offset = found_key.offset - 1;
+		wc.replay_dest->log_root = NULL;
+		free_extent_buffer(log->node);
+		free_extent_buffer(log->commit_root);
+		kfree(log);
+
+		if (found_key.offset == 0)
+			break;
+	}
+	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);
+
+	free_extent_buffer(log_root_tree->node);
+	log_root_tree->log_root = NULL;
+	fs_info->log_root_recovering = 0;
+
+	/* step 4: commit the transaction, which also unpins the blocks */
+	btrfs_commit_transaction(trans, fs_info->tree_root);
+
+	kfree(log_root_tree);
+	return 0;
+
+error:
+	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.
+ */
+void btrfs_record_unlink_dir(struct btrfs_trans_handle *trans,
+			     struct inode *dir, struct 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.
+	 */
+	if (S_ISREG(inode->i_mode))
+		BTRFS_I(inode)->last_unlink_trans = trans->transid;
+
+	/*
+	 * if this directory was already logged any new
+	 * names for this file/dir will get recorded
+	 */
+	smp_mb();
+	if (BTRFS_I(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 (BTRFS_I(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:
+	BTRFS_I(dir)->last_unlink_trans = trans->transid;
+}
+
+/*
+ * Call this after adding a new name for a file and it will properly
+ * update the log to reflect the new name.
+ *
+ * It will return zero if all goes well, and it will return 1 if a
+ * full transaction commit is required.
+ */
+int btrfs_log_new_name(struct btrfs_trans_handle *trans,
+			struct inode *inode, struct inode *old_dir,
+			struct dentry *parent)
+{
+	struct btrfs_root * root = BTRFS_I(inode)->root;
+
+	/*
+	 * this will force the logging code to walk the dentry chain
+	 * up for the file
+	 */
+	if (S_ISREG(inode->i_mode))
+		BTRFS_I(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 (BTRFS_I(inode)->logged_trans <=
+	    root->fs_info->last_trans_committed &&
+	    (!old_dir || BTRFS_I(old_dir)->logged_trans <=
+		    root->fs_info->last_trans_committed))
+		return 0;
+
+	return btrfs_log_inode_parent(trans, root, inode, parent, 1);
+}
+