Searched hist:"19 fa1a6756ed9e92daa9537c03b47d6b55cc2316" (Results 1 – 3 of 3) sorted by relevance
| /openbmc/linux/drivers/md/ |
| H A D | dm-thin-metadata.h | diff 19fa1a6756ed9e92daa9537c03b47d6b55cc2316 Tue Dec 17 11:09:40 CST 2013 Joe Thornber <ejt@redhat.com> dm thin: fix discard support to a previously shared block
If a snapshot is created and later deleted the origin dm_thin_device's
snapshotted_time will have been updated to reflect the snapshot's
creation time. The 'shared' flag in the dm_thin_lookup_result struct
returned from dm_thin_find_block() is an approximation based on
snapshotted_time -- this is done to avoid 0(n), or worse, time
complexity. In this case, the shared flag would be true.
But because the 'shared' flag reflects an approximation a block can be
incorrectly assumed to be shared (e.g. false positive for 'shared'
because the snapshot no longer exists). This could result in discards
issued to a thin device not being passed down to the pool's underlying
data device.
To fix this we double check that a thin block is really still in-use
after a mapping is removed using dm_pool_block_is_used(). If the
reference count for a block is now zero the discard is allowed to be
passed down.
Also add a 'definitely_not_shared' member to the dm_thin_new_mapping
structure -- reflects that the 'shared' flag in the response from
dm_thin_find_block() can only be held as definitive if false is
returned.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1043527
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
|
| H A D | dm-thin-metadata.c | diff 19fa1a6756ed9e92daa9537c03b47d6b55cc2316 Tue Dec 17 11:09:40 CST 2013 Joe Thornber <ejt@redhat.com> dm thin: fix discard support to a previously shared block
If a snapshot is created and later deleted the origin dm_thin_device's
snapshotted_time will have been updated to reflect the snapshot's
creation time. The 'shared' flag in the dm_thin_lookup_result struct
returned from dm_thin_find_block() is an approximation based on
snapshotted_time -- this is done to avoid 0(n), or worse, time
complexity. In this case, the shared flag would be true.
But because the 'shared' flag reflects an approximation a block can be
incorrectly assumed to be shared (e.g. false positive for 'shared'
because the snapshot no longer exists). This could result in discards
issued to a thin device not being passed down to the pool's underlying
data device.
To fix this we double check that a thin block is really still in-use
after a mapping is removed using dm_pool_block_is_used(). If the
reference count for a block is now zero the discard is allowed to be
passed down.
Also add a 'definitely_not_shared' member to the dm_thin_new_mapping
structure -- reflects that the 'shared' flag in the response from
dm_thin_find_block() can only be held as definitive if false is
returned.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1043527
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
|
| H A D | dm-thin.c | diff 19fa1a6756ed9e92daa9537c03b47d6b55cc2316 Tue Dec 17 11:09:40 CST 2013 Joe Thornber <ejt@redhat.com> dm thin: fix discard support to a previously shared block
If a snapshot is created and later deleted the origin dm_thin_device's
snapshotted_time will have been updated to reflect the snapshot's
creation time. The 'shared' flag in the dm_thin_lookup_result struct
returned from dm_thin_find_block() is an approximation based on
snapshotted_time -- this is done to avoid 0(n), or worse, time
complexity. In this case, the shared flag would be true.
But because the 'shared' flag reflects an approximation a block can be
incorrectly assumed to be shared (e.g. false positive for 'shared'
because the snapshot no longer exists). This could result in discards
issued to a thin device not being passed down to the pool's underlying
data device.
To fix this we double check that a thin block is really still in-use
after a mapping is removed using dm_pool_block_is_used(). If the
reference count for a block is now zero the discard is allowed to be
passed down.
Also add a 'definitely_not_shared' member to the dm_thin_new_mapping
structure -- reflects that the 'shared' flag in the response from
dm_thin_find_block() can only be held as definitive if false is
returned.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1043527
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
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