dm era: only resize metadata in preresume

commit cca2c6aebe86f68103a8615074b3578e854b5016 upstream.

Metadata resize shouldn't happen in the ctr. The ctr loads a temporary
(inactive) table that will only become active upon resume. That is why
resize should always be done in terms of resume. Otherwise a load (ctr)
whose inactive table never becomes active will incorrectly resize the
metadata.

Also, perform the resize directly in preresume, instead of using the
worker to do it.

The worker might run other metadata operations, e.g., it could start
digestion, before resizing the metadata. These operations will end up
using the old size.

This could lead to errors, like:

  device-mapper: era: metadata_digest_transcribe_writeset: dm_array_set_value failed
  device-mapper: era: process_old_eras: digest step failed, stopping digestion

The reason of the above error is that the worker started the digestion
of the archived writeset using the old, larger size.

As a result, metadata_digest_transcribe_writeset tried to write beyond
the end of the era array.

Fixes: eec40579d84873 ("dm: add era target")
Cc: stable@vger.kernel.org # v3.15+
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/dm-era-target.c b/drivers/md/dm-era-target.c
index 80abfdd6a9516022e036b513cc7b3f9d8c34f77d..9553bb31918b3288a2e1ced27c363af0f7c664a0 100644 (file)
--- a/drivers/md/dm-era-target.c
+++ b/drivers/md/dm-era-target.c
@@ -1500,15 +1500,6 @@ static int era_ctr(struct dm_target *ti, unsigned argc, char **argv)
        }
        era->md = md;
 
-       era->nr_blocks = calc_nr_blocks(era);
-
-       r = metadata_resize(era->md, &era->nr_blocks);
-       if (r) {
-               ti->error = "couldn't resize metadata";
-               era_destroy(era);
-               return -ENOMEM;
-       }
-
        era->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
        if (!era->wq) {
                ti->error = "could not create workqueue for metadata object";
@@ -1585,9 +1576,17 @@ static int era_preresume(struct dm_target *ti)
        dm_block_t new_size = calc_nr_blocks(era);
 
        if (era->nr_blocks != new_size) {
-               r = in_worker1(era, metadata_resize, &new_size);
-               if (r)
+               r = metadata_resize(era->md, &new_size);
+               if (r) {
+                       DMERR("%s: metadata_resize failed", __func__);
                        return r;
+               }
+
+               r = metadata_commit(era->md);
+               if (r) {
+                       DMERR("%s: metadata_commit failed", __func__);
+                       return r;
+               }
 
                era->nr_blocks = new_size;
        }