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.c b/drivers/md/dm.c
index 16f759f..255b75c 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2077,19 +2077,23 @@
return 0;
}
-static void __unbind(struct mapped_device *md)
+/*
+ * Returns unbound table for the caller to free.
+ */
+static struct dm_table *__unbind(struct mapped_device *md)
{
struct dm_table *map = md->map;
unsigned long flags;
if (!map)
- return;
+ return NULL;
dm_table_event_callback(map, NULL, NULL);
write_lock_irqsave(&md->map_lock, flags);
md->map = NULL;
write_unlock_irqrestore(&md->map_lock, flags);
- dm_table_destroy(map);
+
+ return map;
}
/*
@@ -2182,7 +2186,7 @@
}
dm_sysfs_exit(md);
dm_table_put(map);
- __unbind(md);
+ dm_table_destroy(__unbind(md));
free_dev(md);
}
}
@@ -2368,6 +2372,7 @@
*/
int dm_swap_table(struct mapped_device *md, struct dm_table *table)
{
+ struct dm_table *map;
struct queue_limits limits;
int r = -EINVAL;
@@ -2388,8 +2393,9 @@
goto out;
}
- __unbind(md);
+ map = __unbind(md);
r = __bind(md, table, &limits);
+ dm_table_destroy(map);
out:
mutex_unlock(&md->suspend_lock);