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dm: fix handling of multiple internal suspends 

Commit ffcc393641 ("dm: enhance internal suspend and resume interface")
attempted to handle multiple internal suspends on the same device, but
it did that incorrectly.  When these functions are called in this order
on the same device the device is no longer suspended, but it should be:
	dm_internal_suspend_noflush
	dm_internal_suspend_noflush
	dm_internal_resume

Fix this bug by maintaining an 'internal_suspend_count' and resuming
the device when this count drops to zero.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2015-01-08 18:52:26 -05:00 committed by Mike Snitzer
parent a59db67656
commit 96b26c8c64
1 changed files with 7 additions and 2 deletions
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9
drivers/md/dm.c
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@ -206,6 +206,9 @@ struct mapped_device {
/* zero-length flush that will be cloned and submitted to targets */
struct bio flush_bio;
/* the number of internal suspends */
unsigned internal_suspend_count;
struct dm_stats stats;
};
@ -2928,7 +2931,7 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla
{
struct dm_table *map = NULL;
if (dm_suspended_internally_md(md))
if (md->internal_suspend_count++)
return; /* nested internal suspend */
if (dm_suspended_md(md)) {
@ -2953,7 +2956,9 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla
static void __dm_internal_resume(struct mapped_device *md)
{
if (!dm_suspended_internally_md(md))
BUG_ON(!md->internal_suspend_count);
if (--md->internal_suspend_count)
return; /* resume from nested internal suspend */
if (dm_suspended_md(md))