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| author | David Woodhouse <David.Woodhouse@intel.com> | 2008-08-05 18:01:53 +0100 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-10-09 08:56:01 +0200 |
| commit | fb2dce862d9f9a68e6b9374579056ec9eca02a63 (patch) | |
| tree | 888e0fd7248c9329fa1aa3981043a2dc2457d488 /block/blk-settings.c | |
| parent | d628eaef310533767ce68664873869c2d7f78f09 (diff) | |
| download | linux-fb2dce862d9f9a68e6b9374579056ec9eca02a63.tar.bz2 | |
Add 'discard' request handling
Some block devices benefit from a hint that they can forget the contents
of certain sectors. Add basic support for this to the block core, along
with a 'blkdev_issue_discard()' helper function which issues such
requests.
The caller doesn't get to provide an end_io functio, since
blkdev_issue_discard() will automatically split the request up into
multiple bios if appropriate. Neither does the function wait for
completion -- it's expected that callers won't care about when, or even
_if_, the request completes. It's only a hint to the device anyway. By
definition, the file system doesn't _care_ about these sectors any more.
[With feedback from OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> and
Jens Axboe <jens.axboe@oracle.com]
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk-settings.c')
| -rw-r--r-- | block/blk-settings.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index dfc77012843f..539d873c820d 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -33,6 +33,23 @@ void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn) EXPORT_SYMBOL(blk_queue_prep_rq); /** + * blk_queue_set_discard - set a discard_sectors function for queue + * @q: queue + * @dfn: prepare_discard function + * + * It's possible for a queue to register a discard callback which is used + * to transform a discard request into the appropriate type for the + * hardware. If none is registered, then discard requests are failed + * with %EOPNOTSUPP. + * + */ +void blk_queue_set_discard(struct request_queue *q, prepare_discard_fn *dfn) +{ + q->prepare_discard_fn = dfn; +} +EXPORT_SYMBOL(blk_queue_set_discard); + +/** * blk_queue_merge_bvec - set a merge_bvec function for queue * @q: queue * @mbfn: merge_bvec_fn |