dm ioctl: increase granularity of type_lock when loading table
Hold the mapped device's type_lock before calling populate_table() since
it is where the table's type is determined based on the specified
targets. There is no need to allow concurrent table loads to race to
establish the table's targets or type.
This eliminates the need to grab the lock in dm_table_set_type().
Also verify that the type_lock is held in both dm_set_md_type() and
dm_get_md_type().
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 5667cea..42cca36 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1264,9 +1264,12 @@
if (r)
goto out;
+ /* Protect md->type and md->queue against concurrent table loads. */
+ dm_lock_md_type(md);
r = populate_table(t, param, param_size);
if (r) {
dm_table_destroy(t);
+ dm_unlock_md_type(md);
goto out;
}
@@ -1276,12 +1279,11 @@
DMWARN("can't replace immutable target type %s",
immutable_target_type->name);
dm_table_destroy(t);
+ dm_unlock_md_type(md);
r = -EINVAL;
goto out;
}
- /* Protect md->type and md->queue against concurrent table loads. */
- dm_lock_md_type(md);
if (dm_get_md_type(md) == DM_TYPE_NONE)
/* Initial table load: acquire type of table. */
dm_set_md_type(md, dm_table_get_type(t));