btrfs: Adjust commit-transaction condition to avoid NO_SPACE more

If we have any chance to make a successful write, we should not give up.

This patch adjust commit-transaction condition from:
  pinned >= wanted
to
  left + pinned >= wanted

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
(cherry picked from commit 264ca0f60becac34395f3b42171ad0cc2e53ea6e)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1293c2e100ab3e773ba327ebbebfa56f57cd32cf..4f4abe535cd0b16461f160d2cd9287877b2100e7 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3931,7 +3931,8 @@ alloc:
                 * don't bother committing the transaction.
                 */
                if (percpu_counter_compare(&data_sinfo->total_bytes_pinned,
-                                          bytes) < 0)
+                                          used + bytes -
+                                          data_sinfo->total_bytes) < 0)
                        have_pinned_space = 0;
                spin_unlock(&data_sinfo->lock);