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authorChristoph Hellwig <hch@lst.de>2017-02-08 14:46:49 +0100
committerJens Axboe <axboe@fb.com>2017-02-08 13:43:08 -0700
commit1e739730c5b9ea80a2f25e9cf6e1025d47e3d8ed (patch)
tree4f48ed6c92153fb9941185182e918232eb3472f4 /block/blk-merge.c
parent34fe7c05400663e01e23cddd1fea68bb7a2b3d29 (diff)
downloadlinux-stericsson-1e739730c5b9ea80a2f25e9cf6e1025d47e3d8ed.tar.gz
block: optionally merge discontiguous discard bios into a single request
Add a new merge strategy that merges discard bios into a request until the maximum number of discard ranges (or the maximum discard size) is reached from the plug merging code. I/O scheduler merging is not wired up yet but might also be useful, although not for fast devices like NVMe which are the only user for now. Note that for now we don't support limiting the size of each discard range, but if needed that can be added later. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-merge.c')
-rw-r--r--block/blk-merge.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 6cbd90ad5f90..2afa262425d1 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -803,7 +803,10 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
{
- if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
+ if (req_op(rq) == REQ_OP_DISCARD &&
+ queue_max_discard_segments(rq->q) > 1)
+ return ELEVATOR_DISCARD_MERGE;
+ else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
return ELEVATOR_BACK_MERGE;
else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector)
return ELEVATOR_FRONT_MERGE;