When a dm-mirror device of which error recovery failed is going to
suspend, suspend process could stuck at acquireing semaphore. This
is a call trace when it happened.
dmsetup D 01b014fa 0 2446 6087 0x00000000
f5c2bcb0 00000086 c03a9807 01b014fa 0f87fd46 00000c81 f48ad780 f48ada00
c2c084a0 00000000 c06944a0 c024aa17 00cd3503 ffffffff f5c2bcb4 c023211e
00000000 00000000 000003ff f5f946b4 7fffffff 7fffffff f5c2bcfc c049554e
Call Trace:
[<c049554e>] schedule_timeout+0x17/0x1a5
[<c0496062>] __down+0x4a/0x6b
[<c024aa9f>] down+0x22/0x2f
[<f807919b>] dm_rh_stop_recovery+0x14/0x1d [dm_region_hash]
[<f84c4c92>] mirror_presuspend+0x44/0x12f [dm_mirror]
[<f84af571>] suspend_targets+0x2d/0x3b [dm_mod]
[<f84af58d>] dm_table_presuspend_targets+0xe/0x10 [dm_mod]
[<f84aee56>] dm_suspend+0x4d/0x150 [dm_mod]
[<f84b1fe9>] dev_suspend+0x55/0x18a [dm_mod]
[<f84b29f3>] dm_ctl_ioctl+0x303/0x344 [dm_mod]
[<c02c3c4b>] vfs_ioctl+0x22/0x85
[<c02c422c>] do_vfs_ioctl+0x4cb/0x516
[<c02c42b7>] sys_ioctl+0x40/0x5a
[<c0202858>] sysenter_do_call+0x12/0x28
When an error recovery processes a region with a positive pending count,
__rh_recovery_prepare() returns "1" without adding the region in the
quiesed_regions list. In this case, the semaphore (recovery_count) is
not released. This causes stuck when recovery_count is acquired in
dm_rh_stop_recovery() called from mirror_presuspend().
To prevent the stuck, all bios in the hold list should be processed
after the suspend flag is set but before dm_rh_stop_recovery() is called.
I appreciate your comments.
Thanks,
Taka
Signed-off-by: Takahiro Yasui <tyasui@xxxxxxxxxx>
---
drivers/md/dm-raid1.c | 41 +++++++++++++++++++++++------------------
1 file changed, 23 insertions(+), 18 deletions(-)
Index: linux-2.6.33-rc1-dm/drivers/md/dm-raid1.c
===================================================================
--- linux-2.6.33-rc1-dm.orig/drivers/md/dm-raid1.c
+++ linux-2.6.33-rc1-dm/drivers/md/dm-raid1.c
@@ -465,9 +465,17 @@ static void map_region(struct dm_io_regi
static void hold_bio(struct mirror_set *ms, struct bio *bio)
{
/*
- * If device is suspended, complete the bio.
+ * Lock is required to avoid race condition during suspend
+ * process.
*/
+ spin_lock_irq(&ms->lock);
+
if (atomic_read(&ms->suspend)) {
+ spin_unlock_irq(&ms->lock);
+
+ /*
+ * If device is suspended, complete the bio.
+ */
if (dm_noflush_suspending(ms->ti))
bio_endio(bio, DM_ENDIO_REQUEUE);
else
@@ -478,7 +486,6 @@ static void hold_bio(struct mirror_set *
/*
* Hold bio until the suspend is complete.
*/
- spin_lock_irq(&ms->lock);
bio_list_add(&ms->holds, bio);
spin_unlock_irq(&ms->lock);
}
@@ -1259,6 +1266,20 @@ static void mirror_presuspend(struct dm_
atomic_set(&ms->suspend, 1);
/*
+ * Process bios in the hold list to start recovery waiting
+ * for bios in the hold list. After the process, no bio has
+ * a chance to be added in the hold list because ms->suspend
+ * is set.
+ */
+ spin_lock_irq(&ms->lock);
+ holds = ms->holds;
+ bio_list_init(&ms->holds);
+ spin_unlock_irq(&ms->lock);
+
+ while ((bio = bio_list_pop(&holds)))
+ hold_bio(ms, bio);
+
+ /*
* We must finish up all the work that we've
* generated (i.e. recovery work).
*/
@@ -1278,22 +1299,6 @@ static void mirror_presuspend(struct dm_
* we know that all of our I/O has been pushed.
*/
flush_workqueue(ms->kmirrord_wq);
-
- /*
- * Now set ms->suspend is set and the workqueue flushed, no more
- * entries can be added to ms->hold list, so process it.
- *
- * Bios can still arrive concurrently with or after this
- * presuspend function, but they cannot join the hold list
- * because ms->suspend is set.
- */
- spin_lock_irq(&ms->lock);
- holds = ms->holds;
- bio_list_init(&ms->holds);
- spin_unlock_irq(&ms->lock);
-
- while ((bio = bio_list_pop(&holds)))
- hold_bio(ms, bio);
}
static void mirror_postsuspend(struct dm_target *ti)
--
Takahiro Yasui
Hitachi Computer Products (America), Inc.
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