Don't alloc discard bio with a biovec in blkdev_issue_discard. Doing so means bio_has_data() will not be true until the SCSI layer adds the payload to the discard request via blk_add_request_payload. This patch avoids the need for the following VM accounting fix for discards: http://lkml.org/lkml/2010/6/23/361 NOTE: Jens, you said you applied Tao Ma's fix but I cannot see it in your linux-2.6-block's for-next or for-2.6.36... as such I didn't revert it in this patch. Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- block/blk-core.c | 2 ++ block/blk-lib.c | 2 +- fs/bio.c | 25 +++++++++++++++++++++++-- include/linux/bio.h | 3 +++ 4 files changed, 29 insertions(+), 3 deletions(-) Index: linux-2.6-block/block/blk-core.c =================================================================== --- linux-2.6-block.orig/block/blk-core.c +++ linux-2.6-block/block/blk-core.c @@ -1153,6 +1153,7 @@ void blk_add_request_payload(struct requ { struct bio *bio = rq->bio; + bio_enable_inline_vecs(bio); bio->bi_io_vec->bv_page = page; bio->bi_io_vec->bv_offset = 0; bio->bi_io_vec->bv_len = len; @@ -1187,6 +1188,7 @@ void blk_clear_request_payload(struct re bio->bi_io_vec->bv_page = NULL; bio->bi_io_vec->bv_len = 0; + bio_disable_inline_vecs(bio); } EXPORT_SYMBOL_GPL(blk_clear_request_payload); Index: linux-2.6-block/block/blk-lib.c =================================================================== --- linux-2.6-block.orig/block/blk-lib.c +++ linux-2.6-block/block/blk-lib.c @@ -54,7 +54,7 @@ int blkdev_issue_discard(struct block_de unsigned int max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); - bio = bio_alloc(gfp_mask, 1); + bio = bio_alloc(gfp_mask, 0); if (!bio) { ret = -ENOMEM; break; Index: linux-2.6-block/fs/bio.c =================================================================== --- linux-2.6-block.orig/fs/bio.c +++ linux-2.6-block/fs/bio.c @@ -261,6 +261,27 @@ void bio_init(struct bio *bio) EXPORT_SYMBOL(bio_init); /** + * bio_enable_inline_vecs - enable use of bio's inline iovecs + * @bio: bio that will use its inline iovecs + */ +void bio_enable_inline_vecs(struct bio *bio) +{ + bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET; + bio->bi_max_vecs = BIO_INLINE_VECS; + bio->bi_io_vec = bio->bi_inline_vecs;; +} + +/** + * bio_disable_inline_vecs - disable use of bio's inline iovecs + * @bio: bio that will no longer use its inline iovecs + */ +void bio_disable_inline_vecs(struct bio *bio) +{ + bio->bi_max_vecs = 0; + bio->bi_io_vec = NULL; +} + +/** * bio_alloc_bioset - allocate a bio for I/O * @gfp_mask: the GFP_ mask given to the slab allocator * @nr_iovecs: number of iovecs to pre-allocate @@ -293,8 +314,8 @@ struct bio *bio_alloc_bioset(gfp_t gfp_m goto out_set; if (nr_iovecs <= BIO_INLINE_VECS) { - bvl = bio->bi_inline_vecs; - nr_iovecs = BIO_INLINE_VECS; + bio_enable_inline_vecs(bio); + return bio; } else { bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs); if (unlikely(!bvl)) Index: linux-2.6-block/include/linux/bio.h =================================================================== --- linux-2.6-block.orig/include/linux/bio.h +++ linux-2.6-block/include/linux/bio.h @@ -403,6 +403,9 @@ extern struct bio *bio_clone(struct bio extern void bio_init(struct bio *); +extern void bio_enable_inline_vecs(struct bio *); +extern void bio_disable_inline_vecs(struct bio *); + extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int); extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *, unsigned int, unsigned int); -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
