From c15227de132f1295f3db6b7df9079956b1020fd8 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 30 Sep 2009 13:52:12 +0200 Subject: 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 which did the prepare_discard_fn but not the different payload allocation yet. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- drivers/staging/dst/dcore.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/staging') diff --git a/drivers/staging/dst/dcore.c b/drivers/staging/dst/dcore.c index ac8577358ba..5e8db067758 100644 --- a/drivers/staging/dst/dcore.c +++ b/drivers/staging/dst/dcore.c @@ -102,7 +102,7 @@ static int dst_request(struct request_queue *q, struct bio *bio) struct dst_node *n = q->queuedata; int err = -EIO; - if (bio_empty_barrier(bio) && !q->prepare_discard_fn) { + if (bio_empty_barrier(bio) && !blk_queue_discard(q)) { /* * This is a dirty^Wnice hack, but if we complete this * operation with -EOPNOTSUPP like intended, XFS -- cgit v1.2.3