ext4: yield during large unlinks

During large unlink operations on files with extents, we can use a lot
of CPU time.  This adds a cond_resched() call when starting to examine
the next level of a multi-level extent tree.  Multi-level extent trees
are rare in the first place, and this should rarely be executed.
    
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 593091537e76..cfdc51e30257 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2835,6 +2835,9 @@ again:
                                 err = -EIO;
                                 break;
                         }
+                        /* Yield here to deal with large extent trees.
+                         * Should be a no-op if we did IO above. */
+                        cond_resched();
                         if (WARN_ON(i + 1 > depth)) {
                                 err = -EIO;
                                 break;