path: root/block/blk-settings.c
diff options
authorChristoph Hellwig <hch@infradead.org>2009-09-30 13:52:12 +0200
committerJens Axboe <jens.axboe@oracle.com>2009-10-01 21:19:30 +0200
commitc15227de132f1295f3db6b7df9079956b1020fd8 (patch)
treead06f119f283cf8a6313681055e8132ba2851ddb /block/blk-settings.c
parent3bd0f0c763e497c8674b28e3df2732f48683dabd (diff)
block: use normal I/O path for discard requests
prepare_discard_fn() was being called in a place where memory allocation was effectively impossible. This makes it inappropriate for all but the most trivial translations of Linux's DISCARD operation to the block command set. Additionally adding a payload there makes the ownership of the bio backing unclear as it's now allocated by the device driver and not the submitter as usual. It is replaced with QUEUE_FLAG_DISCARD which is used to indicate whether the queue supports discard operations or not. blkdev_issue_discard now allocates a one-page, sector-length payload which is the right thing for the common ATA and SCSI implementations. The mtd implementation of prepare_discard_fn() is replaced with simply checking for the request being a discard. Largely based on a previous patch from Matthew Wilcox <matthew@wil.cx> which did the prepare_discard_fn but not the different payload allocation yet. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk-settings.c')
1 files changed, 0 insertions, 17 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index eaf122ff5f1..d29498ef1eb 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -34,23 +34,6 @@ void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
- * 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;
* blk_queue_merge_bvec - set a merge_bvec function for queue
* @q: queue
* @mbfn: merge_bvec_fn