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| author | Ilya Dryomov <idryomov@gmail.com> | 2018-02-06 19:26:34 +0100 |
|---|---|---|
| committer | Ilya Dryomov <idryomov@gmail.com> | 2018-04-02 10:12:43 +0200 |
| commit | 2bb1e56ec6450ce533c644c5bfa548dc34c551a0 (patch) | |
| tree | 10b591e350fc80d19b5a46c3798f3be5fa3acbc8 /fs/cifs/dir.c | |
| parent | rbd: move to obj_req->img_extents (diff) | |
| download | linux-2bb1e56ec6450ce533c644c5bfa548dc34c551a0.tar.xz linux-2bb1e56ec6450ce533c644c5bfa548dc34c551a0.zip | |
rbd: create+truncate for whole-object layered discards
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, which violates our "discard zeroes data" promise
and breaks REQ_OP_WRITE_ZEROES implementation.
A non-exclusive create on an existing object is also a no-op, so the
fix is to do a compound create+truncate instead.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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