[PATCH 4.2 118/120] ocfs2: direct write will call ocfs2_rw_unlock() twice when doing aio+dio

Greg Kroah-Hartman
2015-09-19T17:49:47Z

From: Ryan Ding <ryan.ding@oracle.com>

commit aa1057b3dec478b20c77bad07442318ae36d893c upstream.

ocfs2_file_write_iter() is usng the wrong return value ('written'). This
will cause ocfs2_rw_unlock() be called both in write_iter & end_io,
triggering a BUG_ON.

This issue was introduced by commit 7da839c47589 ("ocfs2: use
__generic_file_write_iter()").

Orabug: 21612107
Fixes: 7da839c47589 ("ocfs2: use __generic_file_write_iter()")
Signed-off-by: Ryan Ding <ryan.ding@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ocfs2/file.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)

--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2372,6 +2372,20 @@ relock:
/* buffered aio wouldn't have proper lock coverage today */
BUG_ON(written == -EIOCBQUEUED && !(iocb->ki_flags & IOCB_DIRECT));

+ /*
+ * deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io
+ * function pointer which is called when o_direct io completes so that
+ * it can unlock our rw lock.
+ * Unfortunately there are error cases which call end_io and others
+ * that don't. so we don't have to unlock the rw_lock if either an
+ * async dio is going to do it in the future or an end_io after an
+ * error has already done it.
+ */
+ if ((written == -EIOCBQUEUED) || (!ocfs2_iocb_is_rw_locked(iocb))) {
+ rw_level = -1;
+ unaligned_dio = 0;
+ }
+
if (unlikely(written <= 0))
goto no_sync;

@@ -2396,20 +2410,6 @@ relock:
}

no_sync:
- /*
- * deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io
- * function pointer which is called when o_direct io completes so that
- * it can unlock our rw lock.
- * Unfortunately there are error cases which call end_io and others
- * that don't. so we don't have to unlock the rw_lock if either an
- * async dio is going to do it in the future or an end_io after an
- * error has already done it.
- */
- if ((ret == -EIOCBQUEUED) || (!ocfs2_iocb_is_rw_locked(iocb))) {
- rw_level = -1;
- unaligned_dio = 0;
- }
-
if (unaligned_dio) {
ocfs2_iocb_clear_unaligned_aio(iocb);
mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);