[PATCH] aio: fix lock dep warning

[PATCH] aio: fix lock dep warning

[Shaohua Li]

lockdep reports a warnning. file_start_write/file_end_write only
acquire/release the lock for regular files. So checking the files in aio
side too.

[  453.532141] ------------[ cut here ]------------
[  453.533011] WARNING: CPU: 1 PID: 1298 at ../kernel/locking/lockdep.c:3514 lock_release+0x434/0x670
[  453.533011] DEBUG_LOCKS_WARN_ON(depth <= 0)
[  453.533011] Modules linked in:
[  453.533011] CPU: 1 PID: 1298 Comm: fio Not tainted 4.9.0+ #964
[  453.533011] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.0-1.fc24 04/01/2014
[  453.533011]  ffff8803a24b7a70 ffffffff8196cffb ffff8803a24b7ae8 0000000000000000
[  453.533011]  ffff8803a24b7ab8 ffffffff81091ee1 ffff8803a5dba700 00000dba00000008
[  453.533011]  ffffed0074496f59 ffff8803a5dbaf54 ffff8803ae0f8488 fffffffffffffdef
[  453.533011] Call Trace:
[  453.533011]  [<ffffffff8196cffb>] dump_stack+0x67/0x9c
[  453.533011]  [<ffffffff81091ee1>] __warn+0x111/0x130
[  453.533011]  [<ffffffff81091f97>] warn_slowpath_fmt+0x97/0xb0
[  453.533011]  [<ffffffff81091f00>] ? __warn+0x130/0x130
[  453.533011]  [<ffffffff8191b789>] ? blk_finish_plug+0x29/0x60
[  453.533011]  [<ffffffff811205d4>] lock_release+0x434/0x670
[  453.533011]  [<ffffffff8198af94>] ? import_single_range+0xd4/0x110
[  453.533011]  [<ffffffff81322195>] ? rw_verify_area+0x65/0x140
[  453.533011]  [<ffffffff813aa696>] ? aio_write+0x1f6/0x280
[  453.533011]  [<ffffffff813aa6c9>] aio_write+0x229/0x280
[  453.533011]  [<ffffffff813aa4a0>] ? aio_complete+0x640/0x640
[  453.533011]  [<ffffffff8111df20>] ? debug_check_no_locks_freed+0x1a0/0x1a0
[  453.533011]  [<ffffffff8114793a>] ? debug_lockdep_rcu_enabled.part.2+0x1a/0x30
[  453.533011]  [<ffffffff81147985>] ? debug_lockdep_rcu_enabled+0x35/0x40
[  453.533011]  [<ffffffff812a92be>] ? __might_fault+0x7e/0xf0
[  453.533011]  [<ffffffff813ac9bc>] do_io_submit+0x94c/0xb10
[  453.533011]  [<ffffffff813ac2ae>] ? do_io_submit+0x23e/0xb10
[  453.533011]  [<ffffffff813ac070>] ? SyS_io_destroy+0x270/0x270
[  453.533011]  [<ffffffff8111d7b3>] ? mark_held_locks+0x23/0xc0
[  453.533011]  [<ffffffff8100201a>] ? trace_hardirqs_on_thunk+0x1a/0x1c
[  453.533011]  [<ffffffff813acb90>] SyS_io_submit+0x10/0x20
[  453.533011]  [<ffffffff824f96aa>] entry_SYSCALL_64_fastpath+0x18/0xad
[  453.533011]  [<ffffffff81119190>] ? trace_hardirqs_off_caller+0xc0/0x110
[  453.533011] ---[ end trace b2fbe664d1cc0082 ]---

Cc: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Shaohua Li <shli@fb.com>
---
 fs/aio.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 428484f..0fcb49a 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1085,7 +1085,8 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
 		 * Tell lockdep we inherited freeze protection from submission
 		 * thread.
 		 */
-		__sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+		if (S_ISREG(file_inode(file)->i_mode))
+			__sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE);
 		file_end_write(file);
 	}
 
@@ -1492,7 +1493,8 @@ static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
 		 * by telling it the lock got released so that it doesn't
 		 * complain about held lock when we return to userspace.
 		 */
-		__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+		if (S_ISREG(file_inode(file)->i_mode))
+			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
 	}
 	kfree(iovec);
 	return ret;
-- 
2.9.3

Re: [PATCH] aio: fix lock dep warning

[Christoph Hellwig]

On Tue, Dec 13, 2016 at 12:09:56PM -0800, Shaohua Li wrote:
> lockdep reports a warnning. file_start_write/file_end_write only
> acquire/release the lock for regular files. So checking the files in aio
> side too.

Looks fine,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH] aio: fix lock dep warning

[Shaohua Li]

On Wed, Dec 14, 2016 at 10:56:15AM +0100, Christoph Hellwig wrote:
> On Tue, Dec 13, 2016 at 12:09:56PM -0800, Shaohua Li wrote:
> > lockdep reports a warnning. file_start_write/file_end_write only
> > acquire/release the lock for regular files. So checking the files in aio
> > side too.
> 
> Looks fine,
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Hi Al,

can you pick this one? It's a trival fix, but quite annoying when lockdep is
enabled.

Thanks,
Shaohua