/*
   * 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
   */

  int 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);
  	}

  	return 0;
  }
  
  
  /*
   * 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)) {
  		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) {

  			ret = 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);

  				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);
  	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);

  			}
  			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);
  			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);
  			}
  			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;
  
  		wret = walk_up_log_tree(trans, log, path, &level, wc);
  		if (wret > 0)
  			break;
  		if (wret < 0)
  			ret = wret;
  	}
  
  	/* was the root node processed? if not, catch it here */
  	if (path->nodes[orig_level]) {
  		wc->process_func(log, path->nodes[orig_level], wc,
  			 btrfs_header_generation(path->nodes[orig_level]));
  		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);
  		}
  	}
  
  	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->log_transid < transid + 2 &&
  		 atomic_read(&root->log_commit[index]));
  	return 0;
  }

  static int wait_for_writer(struct btrfs_trans_handle *trans,
  			   struct btrfs_root *root)

  {
  	DEFINE_WAIT(wait);
  	while (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);
  	}

  	return 0;
  }
  
  /*
   * 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);

  	BUG_ON(ret);

  	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) {
  		BUG_ON(ret != -ENOSPC);
  		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);

  	BUG_ON(ret);

  	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;
  	}

  	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;
  	}

  	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)