ocfs2: change ip_unaligned_aio to of type mutex from atomit_t

There is a problem that waitqueue_active() may check stale data thus miss
a wakeup of threads waiting on ip_unaligned_aio.

The valid value of ip_unaligned_aio is only 0 and 1 so we can change it to
be of type mutex thus the above prolem is avoid.  Another benifit is that
mutex which works as FIFO is fairer than wake_up_all().

Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 5 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index aeb44e879c51..ebe44f7dce0b 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -571,7 +571,6 @@ static void ocfs2_dio_end_io(struct kiocb *iocb,
 {
         struct inode *inode = file_inode(iocb->ki_filp);
         int level;
-        wait_queue_head_t *wq = ocfs2_ioend_wq(inode);
 
         /* this io's submitter should not have unlocked this before we could */
         BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
@@ -582,10 +581,7 @@ static void ocfs2_dio_end_io(struct kiocb *iocb,
         if (ocfs2_iocb_is_unaligned_aio(iocb)) {
                 ocfs2_iocb_clear_unaligned_aio(iocb);
 
-                if (atomic_dec_and_test(&OCFS2_I(inode)->ip_unaligned_aio) &&
-                    waitqueue_active(wq)) {
-                        wake_up_all(wq);
-                }
+                mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);
         }
 
         ocfs2_iocb_clear_rw_locked(iocb);