Merge branch 'upstream/bugfix' of git://github.com/jsgf/linux-xen

[~andy/linux] / fs / ext4 / page-io.c

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 78839af7ce29303118a590381dc7eda9a350f15c..92f38ee13f8a9efacadcfac2fe8d674d5500aebc 100644 (file)
--- 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);