1 files changed, 85 insertions, 87 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 29b82a795522..6f757361db53 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -559,7 +559,7 @@ static noinline struct inode *read_one_inode(struct btrfs_root *root,
 	key.objectid = objectid;
 	key.type = BTRFS_INODE_ITEM_KEY;
 	key.offset = 0;
-	inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
+	inode = btrfs_iget(root->fs_info->sb, &key, root);
 	if (IS_ERR(inode))
 		inode = NULL;
 	return inode;
@@ -945,54 +945,32 @@ static noinline int backref_in_log(struct btrfs_root *log,
 				   const char *name, int namelen)
 {
 	struct btrfs_path *path;
-	struct btrfs_inode_ref *ref;
-	unsigned long ptr;
-	unsigned long ptr_end;
-	unsigned long name_ptr;
-	int found_name_len;
-	int item_size;
 	int ret;
-	int match = 0;
 
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
 
 	ret = btrfs_search_slot(NULL, log, key, path, 0, 0);
-	if (ret != 0)
+	if (ret < 0) {
 		goto out;
-
-	ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
-
-	if (key->type == BTRFS_INODE_EXTREF_KEY) {
-		if (btrfs_find_name_in_ext_backref(path->nodes[0],
-						   path->slots[0],
-						   ref_objectid,
-						   name, namelen))
-			match = 1;
-
+	} else if (ret == 1) {
+		ret = 0;
 		goto out;
 	}
 
-	item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
-	ptr_end = ptr + item_size;
-	while (ptr < ptr_end) {
-		ref = (struct btrfs_inode_ref *)ptr;
-		found_name_len = btrfs_inode_ref_name_len(path->nodes[0], ref);
-		if (found_name_len == namelen) {
-			name_ptr = (unsigned long)(ref + 1);
-			ret = memcmp_extent_buffer(path->nodes[0], name,
-						   name_ptr, namelen);
-			if (ret == 0) {
-				match = 1;
-				goto out;
-			}
-		}
-		ptr = (unsigned long)(ref + 1) + found_name_len;
-	}
+	if (key->type == BTRFS_INODE_EXTREF_KEY)
+		ret = !!btrfs_find_name_in_ext_backref(path->nodes[0],
+						       path->slots[0],
+						       ref_objectid,
+						       name, namelen);
+	else
+		ret = !!btrfs_find_name_in_backref(path->nodes[0],
+						   path->slots[0],
+						   name, namelen);
 out:
 	btrfs_free_path(path);
-	return match;
+	return ret;
 }
 
 static inline int __add_inode_ref(struct btrfs_trans_handle *trans,
@@ -1050,10 +1028,13 @@ again:
 					   (unsigned long)(victim_ref + 1),
 					   victim_name_len);
 
-			if (!backref_in_log(log_root, &search_key,
-					    parent_objectid,
-					    victim_name,
-					    victim_name_len)) {
+			ret = backref_in_log(log_root, &search_key,
+					     parent_objectid, victim_name,
+					     victim_name_len);
+			if (ret < 0) {
+				kfree(victim_name);
+				return ret;
+			} else if (!ret) {
 				inc_nlink(&inode->vfs_inode);
 				btrfs_release_path(path);
 
@@ -1115,10 +1096,12 @@ again:
 			search_key.offset = btrfs_extref_hash(parent_objectid,
 							      victim_name,
 							      victim_name_len);
-			ret = 0;
-			if (!backref_in_log(log_root, &search_key,
-					    parent_objectid, victim_name,
-					    victim_name_len)) {
+			ret = backref_in_log(log_root, &search_key,
+					     parent_objectid, victim_name,
+					     victim_name_len);
+			if (ret < 0) {
+				return ret;
+			} else if (!ret) {
 				ret = -ENOENT;
 				victim_parent = read_one_inode(root,
 						parent_objectid);
@@ -1885,30 +1868,6 @@ static noinline int insert_one_name(struct btrfs_trans_handle *trans,
 }
 
 /*
- * Return true if an inode reference exists in the log for the given name,
- * inode and parent inode.
- */
-static bool name_in_log_ref(struct btrfs_root *log_root,
-			    const char *name, const int name_len,
-			    const u64 dirid, const u64 ino)
-{
-	struct btrfs_key search_key;
-
-	search_key.objectid = ino;
-	search_key.type = BTRFS_INODE_REF_KEY;
-	search_key.offset = dirid;
-	if (backref_in_log(log_root, &search_key, dirid, name, name_len))
-		return true;
-
-	search_key.type = BTRFS_INODE_EXTREF_KEY;
-	search_key.offset = btrfs_extref_hash(dirid, name, name_len);
-	if (backref_in_log(log_root, &search_key, dirid, name, name_len))
-		return true;
-
-	return false;
-}
-
-/*
  * take a single entry in a log directory item and replay it into
  * the subvolume.
  *
@@ -2024,8 +1983,31 @@ out:
 	return ret;
 
 insert:
-	if (name_in_log_ref(root->log_root, name, name_len,
-			    key->objectid, log_key.objectid)) {
+	/*
+	 * Check if the inode reference exists in the log for the given name,
+	 * inode and parent inode
+	 */
+	found_key.objectid = log_key.objectid;
+	found_key.type = BTRFS_INODE_REF_KEY;
+	found_key.offset = key->objectid;
+	ret = backref_in_log(root->log_root, &found_key, 0, name, name_len);
+	if (ret < 0) {
+	        goto out;
+	} else if (ret) {
+	        /* The dentry will be added later. */
+	        ret = 0;
+	        update_size = false;
+	        goto out;
+	}
+
+	found_key.objectid = log_key.objectid;
+	found_key.type = BTRFS_INODE_EXTREF_KEY;
+	found_key.offset = key->objectid;
+	ret = backref_in_log(root->log_root, &found_key, key->objectid, name,
+			     name_len);
+	if (ret < 0) {
+		goto out;
+	} else if (ret) {
 		/* The dentry will be added later. */
 		ret = 0;
 		update_size = false;
@@ -2869,7 +2851,7 @@ static int walk_log_tree(struct btrfs_trans_handle *trans,
 	level = btrfs_header_level(log->node);
 	orig_level = level;
 	path->nodes[level] = log->node;
-	extent_buffer_get(log->node);
+	atomic_inc(&log->node->refs);
 	path->slots[level] = 0;
 
 	while (1) {
@@ -2932,7 +2914,8 @@ out:
  * in the tree of log roots
  */
 static int update_log_root(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *log)
+			   struct btrfs_root *log,
+			   struct btrfs_root_item *root_item)
 {
 	struct btrfs_fs_info *fs_info = log->fs_info;
 	int ret;
@@ -2940,10 +2923,10 @@ static int update_log_root(struct btrfs_trans_handle *trans,
 	if (log->log_transid == 1) {
 		/* insert root item on the first sync */
 		ret = btrfs_insert_root(trans, fs_info->log_root_tree,
-				&log->root_key, &log->root_item);
+				&log->root_key, root_item);
 	} else {
 		ret = btrfs_update_root(trans, fs_info->log_root_tree,
-				&log->root_key, &log->root_item);
+				&log->root_key, root_item);
 	}
 	return ret;
 }
@@ -3041,6 +3024,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct btrfs_root *log = root->log_root;
 	struct btrfs_root *log_root_tree = fs_info->log_root_tree;
+	struct btrfs_root_item new_root_item;
 	int log_transid = 0;
 	struct btrfs_log_ctx root_log_ctx;
 	struct blk_plug plug;
@@ -3104,18 +3088,26 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 		goto out;
 	}
 
+	/*
+	 * We _must_ update under the root->log_mutex in order to make sure we
+	 * have a consistent view of the log root we are trying to commit at
+	 * this moment.
+	 *
+	 * We _must_ copy this into a local copy, because we are not holding the
+	 * log_root_tree->log_mutex yet.  This is important because when we
+	 * commit the log_root_tree we must have a consistent view of the
+	 * log_root_tree when we update the super block to point at the
+	 * log_root_tree bytenr.  If we update the log_root_tree here we'll race
+	 * with the commit and possibly point at the new block which we may not
+	 * have written out.
+	 */
 	btrfs_set_root_node(&log->root_item, log->node);
+	memcpy(&new_root_item, &log->root_item, sizeof(new_root_item));
 
 	root->log_transid++;
 	log->log_transid = root->log_transid;
 	root->log_start_pid = 0;
 	/*
-	 * Update or create log root item under the root's log_mutex to prevent
-	 * races with concurrent log syncs that can lead to failure to update
-	 * log root item because it was not created yet.
-	 */
-	ret = update_log_root(trans, log);
-	/*
 	 * 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.
@@ -3135,6 +3127,14 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	mutex_unlock(&log_root_tree->log_mutex);
 
 	mutex_lock(&log_root_tree->log_mutex);
+
+	/*
+	 * Now we are safe to update the log_root_tree because we're under the
+	 * log_mutex, and we're a current writer so we're holding the commit
+	 * open until we drop the log_mutex.
+	 */
+	ret = update_log_root(trans, log, &new_root_item);
+
 	if (atomic_dec_and_test(&log_root_tree->log_writers)) {
 		/* atomic_dec_and_test implies a barrier */
 		cond_wake_up_nomb(&log_root_tree->log_writer_wait);
@@ -4965,7 +4965,7 @@ static int log_conflicting_inodes(struct btrfs_trans_handle *trans,
 		key.objectid = ino;
 		key.type = BTRFS_INODE_ITEM_KEY;
 		key.offset = 0;
-		inode = btrfs_iget(fs_info->sb, &key, root, NULL);
+		inode = btrfs_iget(fs_info->sb, &key, root);
 		/*
 		 * If the other inode that had a conflicting dir entry was
 		 * deleted in the current transaction, we need to log its parent
@@ -4975,8 +4975,7 @@ static int log_conflicting_inodes(struct btrfs_trans_handle *trans,
 			ret = PTR_ERR(inode);
 			if (ret == -ENOENT) {
 				key.objectid = parent;
-				inode = btrfs_iget(fs_info->sb, &key, root,
-						   NULL);
+				inode = btrfs_iget(fs_info->sb, &key, root);
 				if (IS_ERR(inode)) {
 					ret = PTR_ERR(inode);
 				} else {
@@ -5681,7 +5680,7 @@ process_leaf:
 				continue;
 
 			btrfs_release_path(path);
-			di_inode = btrfs_iget(fs_info->sb, &di_key, root, NULL);
+			di_inode = btrfs_iget(fs_info->sb, &di_key, root);
 			if (IS_ERR(di_inode)) {
 				ret = PTR_ERR(di_inode);
 				goto next_dir_inode;
@@ -5807,8 +5806,7 @@ static int btrfs_log_all_parents(struct btrfs_trans_handle *trans,
 				cur_offset = item_size;
 			}
 
-			dir_inode = btrfs_iget(fs_info->sb, &inode_key,
-					       root, NULL);
+			dir_inode = btrfs_iget(fs_info->sb, &inode_key, root);
 			/*
 			 * If the parent inode was deleted, return an error to
 			 * fallback to a transaction commit. This is to prevent
@@ -5882,7 +5880,7 @@ static int log_new_ancestors(struct btrfs_trans_handle *trans,
 		search_key.objectid = found_key.offset;
 		search_key.type = BTRFS_INODE_ITEM_KEY;
 		search_key.offset = 0;
-		inode = btrfs_iget(fs_info->sb, &search_key, root, NULL);
+		inode = btrfs_iget(fs_info->sb, &search_key, root);
 		if (IS_ERR(inode))
 			return PTR_ERR(inode);