Btrfs: fix unprotected ->log_batch

We forget to protect ->log_batch when syncing a file, this patch fix
this problem by atomic operation. And ->log_batch is used to check
if there are parallel sync operations or not, so it is unnecessary to
reset it to 0 after the sync operation of the current log tree complete.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index a9d7815cf58e..793bc89c660f 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1551,9 +1551,9 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
          * ordered range does a filemape_write_and_wait_range which is why we
          * don't do it above like other file systems.
          */
-        root->log_batch++;
+        atomic_inc(&root->log_batch);
         btrfs_wait_ordered_range(inode, start, end);
-        root->log_batch++;
+        atomic_inc(&root->log_batch);
 
         /*
          * check the transaction that last modified this inode