dm: keep old table until after resume succeeded

When swapping a new table into place, retain the old table until
its replacement is in place.

An old check for an empty table is removed because this is enforced
in populate_table().

__unbind() becomes redundant when followed by __bind().

Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index a3d20265ffc1..63fd4de25bda 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -855,7 +855,7 @@ static int do_resume(struct dm_ioctl *param)
         unsigned suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
         struct hash_cell *hc;
         struct mapped_device *md;
-        struct dm_table *new_map;
+        struct dm_table *new_map, *old_map = NULL;
 
         down_write(&_hash_lock);
 
@@ -884,11 +884,11 @@ static int do_resume(struct dm_ioctl *param)
                 if (!dm_suspended(md))
                         dm_suspend(md, suspend_flags);
 
-                r = dm_swap_table(md, new_map);
-                if (r) {
+                old_map = dm_swap_table(md, new_map);
+                if (IS_ERR(old_map)) {
                         dm_table_destroy(new_map);
                         dm_put(md);
-                        return r;
+                        return PTR_ERR(old_map);
                 }
 
                 if (dm_table_get_mode(new_map) & FMODE_WRITE)
@@ -900,6 +900,8 @@ static int do_resume(struct dm_ioctl *param)
         if (dm_suspended(md))
                 r = dm_resume(md);
 
+        if (old_map)
+                dm_table_destroy(old_map);
 
         if (!r) {
                 dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr);