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authorAlasdair G Kergon <agk@redhat.com>2009-12-10 23:52:23 +0000
committerAlasdair G Kergon <agk@redhat.com>2009-12-10 23:52:23 +0000
commita794015597a2d9b437470c7692aac77e5fc08cd2 (patch)
treed25dd56edd53f8f1890ed005b5531ccfa07c28ee /drivers
parent1d0f3ce83200edc5d43723c77c62b09ad6560294 (diff)
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/dm-table.c3
-rw-r--r--drivers/md/dm.c16
2 files changed, 14 insertions, 5 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 1a6cb3c7822..3162b9c3c3f 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -237,6 +237,9 @@ void dm_table_destroy(struct dm_table *t)
{
unsigned int i;
+ if (!t)
+ return;
+
while (atomic_read(&t->holders))
msleep(1);
smp_mb();
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 16f759fe04f..255b75c6154 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2077,19 +2077,23 @@ static int __bind(struct mapped_device *md, struct dm_table *t,
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 @@ void dm_put(struct mapped_device *md)
}
dm_sysfs_exit(md);
dm_table_put(map);
- __unbind(md);
+ dm_table_destroy(__unbind(md));
free_dev(md);
}
}
@@ -2368,6 +2372,7 @@ static void dm_rq_barrier_work(struct work_struct *work)
*/
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 @@ int dm_swap_table(struct mapped_device *md, struct dm_table *table)
goto out;
}
- __unbind(md);
+ map = __unbind(md);
r = __bind(md, table, &limits);
+ dm_table_destroy(map);
out:
mutex_unlock(&md->suspend_lock);