From 66ac0280197981f88774e74b60c8e5f9f07c1dba Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 18 Jun 2010 16:59:42 +0200 Subject: block: don't allocate a payload for discard request Allocating a fixed payload for discard requests always was a horrible hack, and it's not coming to byte us when adding support for discard in DM/MD. So change the code to leave the allocation of a payload to the lowlevel driver. Unfortunately that means we'll need another hack, which allows us to update the various block layer length fields indicating that we have a payload. Instead of hiding this in sd.c, which we already partially do for UNMAP support add a documented helper in the core block layer for it. Signed-off-by: Christoph Hellwig Acked-by: Mike Snitzer Signed-off-by: Jens Axboe --- block/blk-core.c | 32 ++++++++++++++++++++++++++++++++ block/blk-lib.c | 33 ++++++--------------------------- 2 files changed, 38 insertions(+), 27 deletions(-) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 66c3cfe94d0a..3531d8e1da04 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1135,6 +1135,38 @@ void blk_put_request(struct request *req) } EXPORT_SYMBOL(blk_put_request); +/** + * blk_add_request_payload - add a payload to a request + * @rq: request to update + * @page: page backing the payload + * @len: length of the payload. + * + * This allows to later add a payload to an already submitted request by + * a block driver. The driver needs to take care of freeing the payload + * itself. + * + * Note that this is a quite horrible hack and nothing but handling of + * discard requests should ever use it. + */ +void blk_add_request_payload(struct request *rq, struct page *page, + unsigned int len) +{ + struct bio *bio = rq->bio; + + bio->bi_io_vec->bv_page = page; + bio->bi_io_vec->bv_offset = 0; + bio->bi_io_vec->bv_len = len; + + bio->bi_size = len; + bio->bi_vcnt = 1; + bio->bi_phys_segments = 1; + + rq->__data_len = rq->resid_len = len; + rq->nr_phys_segments = 1; + rq->buffer = bio_data(bio); +} +EXPORT_SYMBOL_GPL(blk_add_request_payload); + void init_request_from_bio(struct request *req, struct bio *bio) { req->cpu = bio->bi_comp_cpu; diff --git a/block/blk-lib.c b/block/blk-lib.c index d0216b9f22d4..e16185b0d8e1 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -19,7 +19,6 @@ static void blkdev_discard_end_io(struct bio *bio, int err) if (bio->bi_private) complete(bio->bi_private); - __free_page(bio_page(bio)); bio_put(bio); } @@ -43,7 +42,6 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, int type = flags & BLKDEV_IFL_BARRIER ? DISCARD_BARRIER : DISCARD_NOBARRIER; struct bio *bio; - struct page *page; int ret = 0; if (!q) @@ -53,35 +51,21 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, return -EOPNOTSUPP; while (nr_sects && !ret) { - unsigned int sector_size = q->limits.logical_block_size; unsigned int max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); bio = bio_alloc(gfp_mask, 1); - if (!bio) - goto out; + if (!bio) { + ret = -ENOMEM; + break; + } + bio->bi_sector = sector; bio->bi_end_io = blkdev_discard_end_io; bio->bi_bdev = bdev; if (flags & BLKDEV_IFL_WAIT) bio->bi_private = &wait; - /* - * Add a zeroed one-sector payload as that's what - * our current implementations need. If we'll ever need - * more the interface will need revisiting. - */ - page = alloc_page(gfp_mask | __GFP_ZERO); - if (!page) - goto out_free_bio; - if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size) - goto out_free_page; - - /* - * And override the bio size - the way discard works we - * touch many more blocks on disk than the actual payload - * length. - */ if (nr_sects > max_discard_sectors) { bio->bi_size = max_discard_sectors << 9; nr_sects -= max_discard_sectors; @@ -103,13 +87,8 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, ret = -EIO; bio_put(bio); } + return ret; -out_free_page: - __free_page(page); -out_free_bio: - bio_put(bio); -out: - return -ENOMEM; } EXPORT_SYMBOL(blkdev_issue_discard); -- cgit v1.2.3