[PATCH 5.5 145/367] dm thin metadata: use pool locking at end of dm_pool_metadata_close

Greg Kroah-Hartman
2020-02-10T12:50:38Z

From: Mike Snitzer <snitzer@redhat.com>

commit 44d8ebf436399a40fcd10dd31b29d37823d62fcc upstream.

Ensure that the pool is locked during calls to __commit_transaction and
__destroy_persistent_data_objects. Just being consistent with locking,
but reality is dm_pool_metadata_close is called once pool is being
destroyed so access to pool shouldn't be contended.

Also, use pmd_write_lock_in_core rather than __pmd_write_lock in
dm_pool_commit_metadata and rename __pmd_write_lock to
pmd_write_lock_in_core -- there was no need for the alias.

In addition, verify that the pool is locked in __commit_transaction().

Fixes: 873f258becca ("dm thin metadata: do not write metadata if no changes occurred")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-thin-metadata.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -387,16 +387,15 @@ static int subtree_equal(void *context,
* Variant that is used for in-core only changes or code that
* shouldn't put the pool in service on its own (e.g. commit).
*/
-static inline void __pmd_write_lock(struct dm_pool_metadata *pmd)
+static inline void pmd_write_lock_in_core(struct dm_pool_metadata *pmd)
__acquires(pmd->root_lock)
{
down_write(&pmd->root_lock);
}
-#define pmd_write_lock_in_core(pmd) __pmd_write_lock((pmd))

static inline void pmd_write_lock(struct dm_pool_metadata *pmd)
{
- __pmd_write_lock(pmd);
+ pmd_write_lock_in_core(pmd);
if (unlikely(!pmd->in_service))
pmd->in_service = true;
}
@@ -831,6 +830,7 @@ static int __commit_transaction(struct d
* We need to know if the thin_disk_superblock exceeds a 512-byte sector.
*/
BUILD_BUG_ON(sizeof(struct thin_disk_superblock) > 512);
+ BUG_ON(!rwsem_is_locked(&pmd->root_lock));

if (unlikely(!pmd->in_service))
return 0;
@@ -953,6 +953,7 @@ int dm_pool_metadata_close(struct dm_poo
return -EBUSY;
}

+ pmd_write_lock_in_core(pmd);
if (!dm_bm_is_read_only(pmd->bm) && !pmd->fail_io) {
r = __commit_transaction(pmd);
if (r < 0)
@@ -961,6 +962,7 @@ int dm_pool_metadata_close(struct dm_poo
}
if (!pmd->fail_io)
__destroy_persistent_data_objects(pmd);
+ pmd_write_unlock(pmd);

kfree(pmd);
return 0;
@@ -1841,7 +1843,7 @@ int dm_pool_commit_metadata(struct dm_po
* Care is taken to not have commit be what
* triggers putting the thin-pool in-service.
*/
- __pmd_write_lock(pmd);
+ pmd_write_lock_in_core(pmd);
if (pmd->fail_io)
goto out;