dm thin: switch to read only mode if a mapping insert fails

Switch the thin pool to read-only mode when dm_thin_insert_block() fails
since there is little reason to expect the cause of the failure to be
resolved without further action by user space.

This issue was noticed with the device-mapper-test-suite using:
dmtest run --suite thin-provisioning -n /exhausting_metadata_space_causes_fail_mode/

The quantity of errors logged in this case must be reduced.

before patch:

device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
<snip ... these repeat for a long while ... >
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
device-mapper: thin: 253:4: no free metadata space available.
device-mapper: thin: 253:4: switching pool to read-only mode

after patch:

device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: 253:4: dm_thin_insert_block() failed: error = -28
device-mapper: thin: 253:4: switching pool to read-only mode

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 2c0cf511ec23..24327adc925c 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -640,7 +640,9 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
          */
         r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
         if (r) {
-                DMERR_LIMIT("dm_thin_insert_block() failed");
+                DMERR_LIMIT("%s: dm_thin_insert_block() failed: error = %d",
+                            dm_device_name(pool->pool_md), r);
+                set_pool_mode(pool, PM_READ_ONLY);
                 cell_error(pool, m->cell);
                 goto out;
         }