Btrfs: fix error path in create_pending_snapshot()

This patch fixes the following problem:
- If we failed to deal with the delayed dir items, we should abort transaction,
  just as its comment said. Fix it.
- If root reference or root back reference insertion failed, we should
  abort transaction. Fix it.
- Fix the double free problem of pending->inherit.
- Do not restore the trans->rsv if we doesn't change it.
- make the error path more clearly.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index ffc6b52..7be0318 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -967,18 +967,16 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        u64 root_flags;
        uuid_le new_uuid;
 
-       rsv = trans->block_rsv;
-
        new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
        if (!new_root_item) {
                ret = pending->error = -ENOMEM;
-               goto fail;
+               goto root_item_alloc_fail;
        }
 
        ret = btrfs_find_free_objectid(tree_root, &objectid);
        if (ret) {
                pending->error = ret;
-               goto fail;
+               goto no_free_objectid;
        }
 
        btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
@@ -988,22 +986,22 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
                                                  to_reserve);
                if (ret) {
                        pending->error = ret;
-                       goto fail;
+                       goto no_free_objectid;
                }
        }
 
        ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
                                   objectid, pending->inherit);
-       kfree(pending->inherit);
        if (ret) {
                pending->error = ret;
-               goto fail;
+               goto no_free_objectid;
        }
 
        key.objectid = objectid;
        key.offset = (u64)-1;
        key.type = BTRFS_ROOT_ITEM_KEY;
 
+       rsv = trans->block_rsv;
        trans->block_rsv = &pending->block_rsv;
 
        dentry = pending->dentry;
@@ -1023,10 +1021,9 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
                                BTRFS_FT_DIR, index);
        if (ret == -EEXIST) {
                pending->error = -EEXIST;
-               dput(parent);
                goto fail;
        } else if (ret) {
-               goto abort_trans_dput;
+               goto abort_trans;
        }
 
        btrfs_i_size_write(parent_inode, parent_inode->i_size +
@@ -1034,7 +1031,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
        ret = btrfs_update_inode(trans, parent_root, parent_inode);
        if (ret)
-               goto abort_trans_dput;
+               goto abort_trans;
 
        /*
         * pull in the delayed directory update
@@ -1043,10 +1040,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         * snapshot
         */
        ret = btrfs_run_delayed_items(trans, root);
-       if (ret) { /* Transaction aborted */
-               dput(parent);
-               goto fail;
-       }
+       if (ret)        /* Transaction aborted */
+               goto abort_trans;
 
        record_root_in_trans(trans, root);
        btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
@@ -1079,7 +1074,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        if (ret) {
                btrfs_tree_unlock(old);
                free_extent_buffer(old);
-               goto abort_trans_dput;
+               goto abort_trans;
        }
 
        btrfs_set_lock_blocking(old);
@@ -1089,7 +1084,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        btrfs_tree_unlock(old);
        free_extent_buffer(old);
        if (ret)
-               goto abort_trans_dput;
+               goto abort_trans;
 
        /* see comments in should_cow_block() */
        root->force_cow = 1;
@@ -1102,7 +1097,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        btrfs_tree_unlock(tmp);
        free_extent_buffer(tmp);
        if (ret)
-               goto abort_trans_dput;
+               goto abort_trans;
 
        /*
         * insert root back/forward references
@@ -1111,9 +1106,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
                                 parent_root->root_key.objectid,
                                 btrfs_ino(parent_inode), index,
                                 dentry->d_name.name, dentry->d_name.len);
-       dput(parent);
        if (ret)
-               goto fail;
+               goto abort_trans;
 
        key.offset = (u64)-1;
        pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
@@ -1125,15 +1119,15 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        ret = btrfs_reloc_post_snapshot(trans, pending);
        if (ret)
                goto abort_trans;
-       ret = 0;
 fail:
-       kfree(new_root_item);
+       dput(parent);
        trans->block_rsv = rsv;
+no_free_objectid:
+       kfree(new_root_item);
+root_item_alloc_fail:
        btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
        return ret;
 
-abort_trans_dput:
-       dput(parent);
 abort_trans:
        btrfs_abort_transaction(trans, root, ret);
        goto fail;