dm: bind new table before destroying old
When replacing a mapped device's table during a 'resume', delay the
destruction of the old table until the new one is successfully in place.
This will make it easier for a later patch to transfer internal state
information from the old table to the new one (something we do not currently
support) while giving us more options for reversion if a later part
of the operation fails.
Devices are always in the suspended state during dm_swap_table().
This patch reinforces the requirement that all I/O must have been
flushed from the table targets while in this state (including any in
workqueues). In the case of 'noflush' suspending, unprocessed
I/O should have been 'pushed back' to the dm core prior to this point,
for resubmission after the new table is in place.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 1a6cb3c..3162b9c 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -237,6 +237,9 @@
{
unsigned int i;
+ if (!t)
+ return;
+
while (atomic_read(&t->holders))
msleep(1);
smp_mb();