librbd: create+truncate for whole-object layered discards #20809
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... otherwise object map expectations aren't actually set. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
…cate This is !is_no_op_for_nonexistent_object() test -- NONEXISTENT case is the interesting one. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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@idryomov Can you create a tracker ticket for this issue so that it can be backported to jewel and luminous? |
A whole-object layered discard is implemented as a truncate rather than a delete: a dummy object is needed to prevent the CoW machinery from kicking in. However, a truncate on a non-existent object is a no-op. If the object doesn't exist in HEAD, a discard request is effectively ignored -- parent blocks are still seen afterwards. A non-exclusive create on an existing object is also a no-op, so the fix is to do a compound create+truncate instead. Fixes: http://tracker.ceph.com/issues/23285 Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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Created and rebased to link it from the commit. |
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retest this please |
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retest this please |
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retest this please |
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retest this please |
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(I'm really scratching my head to figure out why the |
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retest this please |
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Merged manually |
dillaman
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…ncate librbd: create+truncate for whole-object layered discards Reviewed-by: Jason Dillaman <dillaman@redhat.com>
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Undo the fixup made in merge commit a7351ce ("Merge pull request ceph#20809 from idryomov/wip-librbd-discard-create-truncate"). We do want to observe the object map interaction here -- specific changes towards that were made in commits 513baf9 ("test/librbd: clone with parent features in DiscardRemoveTruncate") and 9d6ee9a ("test/librbd: expect_object_may_exist(..., false) in DiscardRemoveTruncate"). Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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