Merge branch 'kprobes-test' of git://git.yxit.co.uk/linux into devel-stable

1 files changed, 17 insertions, 1 deletions

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 78839af7ce29..92f38ee13f8a 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -142,7 +142,23 @@ static void ext4_end_io_work(struct work_struct *work)
         unsigned long           flags;
         int                     ret;
 
-        mutex_lock(&inode->i_mutex);
+        if (!mutex_trylock(&inode->i_mutex)) {
+                /*
+                 * Requeue the work instead of waiting so that the work
+                 * items queued after this can be processed.
+                 */
+                queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work);
+                /*
+                 * To prevent the ext4-dio-unwritten thread from keeping
+                 * requeueing end_io requests and occupying cpu for too long,
+                 * yield the cpu if it sees an end_io request that has already
+                 * been requeued.
+                 */
+                if (io->flag & EXT4_IO_END_QUEUED)
+                        yield();
+                io->flag |= EXT4_IO_END_QUEUED;
+                return;
+        }
         ret = ext4_end_io_nolock(io);
         if (ret < 0) {
                 mutex_unlock(&inode->i_mutex);