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>

1 files changed, 17 insertions, 23 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index ffc6b5202d5..7be03185327 100644
--- 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;