From 6ac56951dc10232e24419f6972fc8131dd0166e0 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Mon, 22 May 2017 19:59:24 +0200 Subject: [PATCH] rbd: implement REQ_OP_WRITE_ZEROES Commit 93c1defedcae ("rbd: remove the discard_zeroes_data flag") explicitly didn't implement REQ_OP_WRITE_ZEROES for rbd, while the following commit 48920ff2a5a9 ("block: remove the discard_zeroes_data flag") dropped ->discard_zeroes_data in favor of REQ_OP_WRITE_ZEROES. rbd does support efficient zeroing via CEPH_OSD_OP_ZERO opcode and will release either some or all blocks depending on whether the zeroing request is rbd_obj_bytes() aligned. This is how we currently implement discards, so REQ_OP_WRITE_ZEROES can be identical to REQ_OP_DISCARD for now. Caveats: - REQ_NOUNMAP is ignored, but AFAICT that's true of at least two other current implementations - nvme and loop - there is no ->write_zeroes_alignment and blk_bio_write_zeroes_split() is hence less helpful than blk_bio_discard_split(), but this can (and should) be fixed on the rbd side In the future we will split these into two code paths to respect REQ_NOUNMAP on zeroout and save on zeroing blocks that couldn't be released on discard. Fixes: 93c1defedcae ("rbd: remove the discard_zeroes_data flag") Signed-off-by: Ilya Dryomov Reviewed-by: Jason Dillaman Reviewed-by: Christoph Hellwig --- drivers/block/rbd.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 454bf9c34882..c16f74547804 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -4023,6 +4023,7 @@ static void rbd_queue_workfn(struct work_struct *work) switch (req_op(rq)) { case REQ_OP_DISCARD: + case REQ_OP_WRITE_ZEROES: op_type = OBJ_OP_DISCARD; break; case REQ_OP_WRITE: @@ -4420,6 +4421,7 @@ static int rbd_init_disk(struct rbd_device *rbd_dev) q->limits.discard_granularity = segment_size; q->limits.discard_alignment = segment_size; blk_queue_max_discard_sectors(q, segment_size / SECTOR_SIZE); + blk_queue_max_write_zeroes_sectors(q, segment_size / SECTOR_SIZE); if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC)) q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;