Il 14/08/2012 15:53, Liu Bo ha scritto:
On 08/14/2012 08:59 PM, Marco Stornelli wrote:
Il 14/08/2012 07:01, liub.liubo@xxxxxxxxx ha scritto:
From: Liu Bo <bo.li.liu@xxxxxxxxxx>
I found this while testing xfstests 068, the story is
t1 t2
sys_sync thaw_super
iterate_supers
down_read(sb->s_umount) down_write(sb->s_umount) --->wait for t1
sync_fs (with wait mode)
start_transaction
sb_start_intwrite --------------------> wait for t2 to set s_writers.frozen to SB_UNFROZEN
In this patch, I add an helper sb_start_intwrite_trylock() and use it before we
start_transaction in sync_fs() with wait mode so that we won't hit the deadlock.
IMHO, we should avoid to call the sync operation on a frozen fs. The freeze operation, indeed, already include a sync operation.
According to man page, no other operation should modify the fs after the freeze.
So for me the modification is inside sync_filesystem (and sync_one_sb).
Do you mean that we should add the trylock check in sync_filesystem?
But it seems to be useless because we already run into down_read(sb->s_umount) before starting sync_one_sb().
thanks,
liubo
I meant that we should check if there are in a "complete" freeze state
(according to the "states" of a freeze transaction) and simply skip the
sync operation.
Marco
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
