0, 1 and <0 can be returned by btrfs_next_leaf(), and when <0 is
returned, path->nodes[0] could be NULL, log_dir_items lacks such a
check for <0 and we may run into a null pointer dereference panic.

Fixes: e02119d5a7b4 ("Btrfs: Add a write ahead tree log to optimize synchronous 
operations")
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
Signed-off-by: Liu Bo <bo....@linux.alibaba.com>
---
v2: Add Fixes tag and reviewed-by.

 fs/btrfs/tree-log.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 4344577..4ee9431 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3518,8 +3518,11 @@ static noinline int log_dir_items(struct 
btrfs_trans_handle *trans,
                 * from this directory and from this transaction
                 */
                ret = btrfs_next_leaf(root, path);
-               if (ret == 1) {
-                       last_offset = (u64)-1;
+               if (ret) {
+                       if (ret == 1)
+                               last_offset = (u64)-1;
+                       else
+                               err = ret;
                        goto done;
                }
                btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]);
-- 
1.8.3.1

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