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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-core.c
parent3bd0f0c763e497c8674b28e3df2732f48683dabd (diff)
downloadlinux-2.6.34-ux500-c15227de132f1295f3db6b7df9079956b1020fd8.tar.gz
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-core.c')
-rw-r--r--block/blk-core.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 8135228e4b2..80a020dd158 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1124,7 +1124,6 @@ void init_request_from_bio(struct request *req, struct bio *bio)
req->cmd_flags |= REQ_DISCARD;
if (bio_rw_flagged(bio, BIO_RW_BARRIER))
req->cmd_flags |= REQ_SOFTBARRIER;
- req->q->prepare_discard_fn(req->q, req);
} else if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER)))
req->cmd_flags |= REQ_HARDBARRIER;
@@ -1470,7 +1469,7 @@ static inline void __generic_make_request(struct bio *bio)
goto end_io;
if (bio_rw_flagged(bio, BIO_RW_DISCARD) &&
- !q->prepare_discard_fn) {
+ !blk_queue_discard(q)) {
err = -EOPNOTSUPP;
goto end_io;
}