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author | Mike Snitzer <snitzer@redhat.com> | 2015-11-23 13:44:38 -0500 |
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committer | Mike Snitzer <snitzer@redhat.com> | 2015-11-23 14:54:46 -0500 |
commit | 0fcb04d59351f790efb8da18edefd6ab4d9bbf3b (patch) | |
tree | 49262cdba058160c53fe4a88e385f3ad037f883f /kernel | |
parent | bcbd94ff481ec1d7b5c824d90df82d0faafabd35 (diff) |
dm thin: fix regression in advertised discard limits
When establishing a thin device's discard limits we cannot rely on the
underlying thin-pool device's discard capabilities (which are inherited
from the thin-pool's underlying data device) given that DM thin devices
must provide discard support even when the thin-pool's underlying data
device doesn't support discards.
Users were exposed to this thin device discard limits regression if
their thin-pool's underlying data device does _not_ support discards.
This regression caused all upper-layers that called the
blkdev_issue_discard() interface to not be able to issue discards to
thin devices (because discard_granularity was 0). This regression
wasn't caught earlier because the device-mapper-test-suite's extensive
'thin-provisioning' discard tests are only ever performed against
thin-pool's with data devices that support discards.
Fix is to have thin_io_hints() test the pool's 'discard_enabled' feature
rather than inferring whether or not a thin device's discard support
should be enabled by looking at the thin-pool's discard_granularity.
Fixes: 216076705 ("dm thin: disable discard support for thin devices if pool's is disabled")
Reported-by: Mike Gerber <mike@sprachgewalt.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 4.1+
Diffstat (limited to 'kernel')
0 files changed, 0 insertions, 0 deletions