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* Re: [PATCH] raid5-ppl: silence a misleading warning message
From: Artur Paszkiewicz @ 2017-03-23 12:00 UTC (permalink / raw)
  To: Dan Carpenter, Shaohua Li; +Cc: linux-raid, kernel-janitors
In-Reply-To: <20170321204305.GC22118@mwanda>

On 03/21/2017 09:43 PM, Dan Carpenter wrote:
> The "need_cache_flush" variable is never set to false.  When the
> variable is true that means we print a warning message at the end of
> the function.
> 
> Fixes: 3418d036c81d ("raid5-ppl: Partial Parity Log write logging implementation")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Good catch, thanks. I thought gcc would warn about such issues, I'll
have to be more careful.

Reviewed-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>

^ permalink raw reply

* RFC: always use REQ_OP_WRITE_ZEROES for zeroing offload
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid

This series makes REQ_OP_WRITE_ZEROES the only zeroing offload
supported by the block layer, and switches existing implementations
of REQ_OP_DISCARD that correctly set discard_zeroes_data to it,
removes incorrect discard_zeroes_data, and also switches WRITE SAME
based zeroing in SCSI to this new method.

I've done testing with ATA, SCSI and NVMe setups, but there are
a few things that will need more attention:

 - what is dm-kcopyd doing with the current WRITE SAME usage
   that gets multiple biovecs?  Can we fix it up in any way.
 - what are we going to do with discards through parity raid?
   I suspect we should either just disable it for now entirely
   or modify raid5.c to issue REQ_OP_WRITE_ZEROES to the underlying
   devices.  But I need someone with such a setup to test it.
 - The DRBD code in this area was very odd, and will need an
   audit from the maintainers.

Note that this series needs to be applied on top of the
"support ranges TRIM for libata" series.

A git tree is also avaiable at:

    git://git.infradead.org/users/hch/block.git discard-rework

Gitweb:

    http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/discard-rework

^ permalink raw reply

* [PATCH 01/23] block: renumber REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Make life easy for implementations that needs to send a data buffer
to the device (e.g. SCSI) by numbering it as a data out command.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/blk_types.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index d703acb55d0f..6393c13a6498 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -160,7 +160,7 @@ enum req_opf {
 	/* write the same sector many times */
 	REQ_OP_WRITE_SAME	= 7,
 	/* write the zero filled sector many times */
-	REQ_OP_WRITE_ZEROES	= 8,
+	REQ_OP_WRITE_ZEROES	= 9,
 
 	/* SCSI passthrough using struct scsi_request */
 	REQ_OP_SCSI_IN		= 32,
-- 
2.11.0

^ permalink raw reply related

* [PATCH 02/23] block: implement splitting of REQ_OP_WRITE_ZEROES bios
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Copy and past the REQ_OP_WRITE_SAME code to prepare to implementations
that limit the write zeroes size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-merge.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index c62a6f0325e0..f9e5a3e0944b 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -63,6 +63,20 @@ static struct bio *blk_bio_discard_split(struct request_queue *q,
 	return bio_split(bio, split_sectors, GFP_NOIO, bs);
 }
 
+static struct bio *blk_bio_write_zeroes_split(struct request_queue *q,
+		struct bio *bio, struct bio_set *bs, unsigned *nsegs)
+{
+	*nsegs = 1;
+
+	if (!q->limits.max_write_zeroes_sectors)
+		return NULL;
+
+	if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors)
+		return NULL;
+
+	return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs);
+}
+
 static struct bio *blk_bio_write_same_split(struct request_queue *q,
 					    struct bio *bio,
 					    struct bio_set *bs,
@@ -209,8 +223,7 @@ void blk_queue_split(struct request_queue *q, struct bio **bio,
 		split = blk_bio_discard_split(q, *bio, bs, &nsegs);
 		break;
 	case REQ_OP_WRITE_ZEROES:
-		split = NULL;
-		nsegs = (*bio)->bi_phys_segments;
+		split = blk_bio_write_zeroes_split(q, *bio, bs, &nsegs);
 		break;
 	case REQ_OP_WRITE_SAME:
 		split = blk_bio_write_same_split(q, *bio, bs, &nsegs);
-- 
2.11.0

^ permalink raw reply related

* [PATCH 03/23] sd: implement REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/sd.c     | 45 ++++++++++++++++++++++++++++++++++++++++-----
 drivers/scsi/sd_zbc.c |  1 +
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index af632e350ab4..b6f70a09a301 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -748,7 +748,7 @@ static int sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
 	return scsi_init_io(cmd);
 }
 
-static int sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd)
+static int sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd, bool unmap)
 {
 	struct scsi_device *sdp = cmd->device;
 	struct request *rq = cmd->request;
@@ -765,13 +765,14 @@ static int sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd)
 
 	cmd->cmd_len = 16;
 	cmd->cmnd[0] = WRITE_SAME_16;
-	cmd->cmnd[1] = 0x8; /* UNMAP */
+	if (unmap)
+		cmd->cmnd[1] = 0x8; /* UNMAP */
 	put_unaligned_be64(sector, &cmd->cmnd[2]);
 	put_unaligned_be32(nr_sectors, &cmd->cmnd[10]);
 
 	cmd->allowed = SD_MAX_RETRIES;
 	cmd->transfersize = data_len;
-	rq->timeout = SD_TIMEOUT;
+	rq->timeout = unmap ? SD_TIMEOUT : SD_WRITE_SAME_TIMEOUT;
 	scsi_req(rq)->resid_len = data_len;
 
 	return scsi_init_io(cmd);
@@ -801,7 +802,7 @@ static int sd_setup_write_same10_cmnd(struct scsi_cmnd *cmd, bool unmap)
 
 	cmd->allowed = SD_MAX_RETRIES;
 	cmd->transfersize = data_len;
-	rq->timeout = SD_TIMEOUT;
+	rq->timeout = unmap ? SD_TIMEOUT : SD_WRITE_SAME_TIMEOUT;
 	scsi_req(rq)->resid_len = data_len;
 
 	return scsi_init_io(cmd);
@@ -857,11 +858,39 @@ static int sd_setup_ata_trim_cmnd(struct scsi_cmnd *cmd)
 	return scsi_init_io(cmd);
 }
 
+static int sd_setup_write_zeroes_cmnd(struct scsi_cmnd *cmd)
+{
+	struct request *rq = cmd->request;
+	struct scsi_device *sdp = cmd->device;
+	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
+	u64 sector = blk_rq_pos(rq) >> (ilog2(sdp->sector_size) - 9);
+	u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9);
+
+	if (sdp->ata_trim) {
+		if (!sdp->ata_trim_zeroes_data)
+			return BLKPREP_INVALID;
+		return sd_setup_ata_trim_cmnd(cmd);
+	}
+	if (sdp->no_write_same)
+		return BLKPREP_INVALID;
+	if (sdkp->ws16 || sector > 0xffffffff || nr_sectors > 0xffff)
+		return sd_setup_write_same16_cmnd(cmd, false);
+	return sd_setup_write_same10_cmnd(cmd, false);
+}
+
 static void sd_config_write_same(struct scsi_disk *sdkp)
 {
 	struct request_queue *q = sdkp->disk->queue;
 	unsigned int logical_block_size = sdkp->device->sector_size;
 
+	if (sdkp->device->ata_trim) {
+		if (sdkp->device->ata_trim_zeroes_data)
+			sdkp->max_ws_blocks = 65535 * (512 / sizeof(__le64));
+		else
+			sdkp->max_ws_blocks = 0;
+		goto config_write_zeroes;
+	}
+
 	if (sdkp->device->no_write_same) {
 		sdkp->max_ws_blocks = 0;
 		goto out;
@@ -886,6 +915,9 @@ static void sd_config_write_same(struct scsi_disk *sdkp)
 out:
 	blk_queue_max_write_same_sectors(q, sdkp->max_ws_blocks *
 					 (logical_block_size >> 9));
+config_write_zeroes:
+	blk_queue_max_write_zeroes_sectors(q, sdkp->max_ws_blocks *
+					 (logical_block_size >> 9));
 }
 
 /**
@@ -1226,7 +1258,7 @@ static int sd_init_command(struct scsi_cmnd *cmd)
 		case SD_LBP_UNMAP:
 			return sd_setup_unmap_cmnd(cmd);
 		case SD_LBP_WS16:
-			return sd_setup_write_same16_cmnd(cmd);
+			return sd_setup_write_same16_cmnd(cmd, true);
 		case SD_LBP_WS10:
 			return sd_setup_write_same10_cmnd(cmd, true);
 		case SD_LBP_ZERO:
@@ -1236,6 +1268,8 @@ static int sd_init_command(struct scsi_cmnd *cmd)
 		default:
 			return BLKPREP_INVALID;
 		}
+	case REQ_OP_WRITE_ZEROES:
+		return sd_setup_write_zeroes_cmnd(cmd);
 	case REQ_OP_WRITE_SAME:
 		return sd_setup_write_same_cmnd(cmd);
 	case REQ_OP_FLUSH:
@@ -1876,6 +1910,7 @@ static int sd_done(struct scsi_cmnd *SCpnt)
 
 	switch (req_op(req)) {
 	case REQ_OP_DISCARD:
+	case REQ_OP_WRITE_ZEROES:
 	case REQ_OP_WRITE_SAME:
 	case REQ_OP_ZONE_RESET:
 		if (!result) {
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index 92620c8ea8ad..1994f7799fce 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -329,6 +329,7 @@ void sd_zbc_complete(struct scsi_cmnd *cmd,
 
 	switch (req_op(rq)) {
 	case REQ_OP_WRITE:
+	case REQ_OP_WRITE_ZEROES:
 	case REQ_OP_WRITE_SAME:
 	case REQ_OP_ZONE_RESET:
 
-- 
2.11.0

^ permalink raw reply related

* [PATCH 04/23] md: support REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Copy & paste from the REQ_OP_WRITE_SAME code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/linear.c    | 1 +
 drivers/md/md.h        | 7 +++++++
 drivers/md/multipath.c | 1 +
 drivers/md/raid0.c     | 2 ++
 drivers/md/raid1.c     | 4 +++-
 drivers/md/raid10.c    | 1 +
 drivers/md/raid5.c     | 1 +
 7 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 3e38e0207a3e..377a8a3672e3 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -293,6 +293,7 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio)
 						      split, disk_devt(mddev->gendisk),
 						      bio_sector);
 			mddev_check_writesame(mddev, split);
+			mddev_check_write_zeroes(mddev, split);
 			generic_make_request(split);
 		}
 	} while (split != bio);
diff --git a/drivers/md/md.h b/drivers/md/md.h
index dde8ecb760c8..1e76d64ce180 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -709,4 +709,11 @@ static inline void mddev_check_writesame(struct mddev *mddev, struct bio *bio)
 	    !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors)
 		mddev->queue->limits.max_write_same_sectors = 0;
 }
+
+static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio)
+{
+	if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
+	    !bdev_get_queue(bio->bi_bdev)->limits.max_write_zeroes_sectors)
+		mddev->queue->limits.max_write_zeroes_sectors = 0;
+}
 #endif /* _MD_MD_H */
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index 79a12b59250b..e95d521d93e9 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -139,6 +139,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio)
 	mp_bh->bio.bi_end_io = multipath_end_request;
 	mp_bh->bio.bi_private = mp_bh;
 	mddev_check_writesame(mddev, &mp_bh->bio);
+	mddev_check_write_zeroes(mddev, &mp_bh->bio);
 	generic_make_request(&mp_bh->bio);
 	return;
 }
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 93347ca7c7a6..ce7a6a56cf73 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -383,6 +383,7 @@ static int raid0_run(struct mddev *mddev)
 
 		blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 		blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
+		blk_queue_max_write_zeroes_sectors(mddev->queue, mddev->chunk_sectors);
 		blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
 
 		blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
@@ -504,6 +505,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 						      split, disk_devt(mddev->gendisk),
 						      bio_sector);
 			mddev_check_writesame(mddev, split);
+			mddev_check_write_zeroes(mddev, split);
 			generic_make_request(split);
 		}
 	} while (split != bio);
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index a34f58772022..b59cc100320a 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3177,8 +3177,10 @@ static int raid1_run(struct mddev *mddev)
 	if (IS_ERR(conf))
 		return PTR_ERR(conf);
 
-	if (mddev->queue)
+	if (mddev->queue) {
 		blk_queue_max_write_same_sectors(mddev->queue, 0);
+		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
+	}
 
 	rdev_for_each(rdev, mddev) {
 		if (!mddev->gendisk)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index e89a8d78a9ed..28ec3a93acee 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3749,6 +3749,7 @@ static int raid10_run(struct mddev *mddev)
 		blk_queue_max_discard_sectors(mddev->queue,
 					      mddev->chunk_sectors);
 		blk_queue_max_write_same_sectors(mddev->queue, 0);
+		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
 		blk_queue_io_min(mddev->queue, chunk_size);
 		if (conf->geo.raid_disks % conf->geo.near_copies)
 			blk_queue_io_opt(mddev->queue, chunk_size * conf->geo.raid_disks);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ed5cd705b985..8cf1f86dcd05 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7272,6 +7272,7 @@ static int raid5_run(struct mddev *mddev)
 		mddev->queue->limits.discard_zeroes_data = 0;
 
 		blk_queue_max_write_same_sectors(mddev->queue, 0);
+		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
 
 		rdev_for_each(rdev, mddev) {
 			disk_stack_limits(mddev->gendisk, rdev->bdev,
-- 
2.11.0

^ permalink raw reply related

* [PATCH 05/23] dm: support REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Copy & paste from the REQ_OP_WRITE_SAME code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/dm-core.h          |  1 +
 drivers/md/dm-io.c            | 10 +++++++---
 drivers/md/dm-linear.c        |  1 +
 drivers/md/dm-mpath.c         |  1 +
 drivers/md/dm-rq.c            | 11 ++++++++---
 drivers/md/dm-stripe.c        |  2 ++
 drivers/md/dm-table.c         | 30 ++++++++++++++++++++++++++++++
 drivers/md/dm.c               | 31 ++++++++++++++++++++++++++++---
 include/linux/device-mapper.h |  6 ++++++
 9 files changed, 84 insertions(+), 9 deletions(-)

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index 136fda3ff9e5..fea5bd52ada8 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -132,6 +132,7 @@ void dm_init_md_queue(struct mapped_device *md);
 void dm_init_normal_md_queue(struct mapped_device *md);
 int md_in_flight(struct mapped_device *md);
 void disable_write_same(struct mapped_device *md);
+void disable_write_zeroes(struct mapped_device *md);
 
 static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
 {
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 03940bf36f6c..fad2d5d1888e 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -312,9 +312,12 @@ static void do_region(int op, int op_flags, unsigned region,
 	 */
 	if (op == REQ_OP_DISCARD)
 		special_cmd_max_sectors = q->limits.max_discard_sectors;
+	else if (op == REQ_OP_WRITE_ZEROES)
+		special_cmd_max_sectors = q->limits.max_write_zeroes_sectors;
 	else if (op == REQ_OP_WRITE_SAME)
 		special_cmd_max_sectors = q->limits.max_write_same_sectors;
-	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_SAME) &&
+	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES ||
+	     op == REQ_OP_WRITE_SAME)  &&
 	    special_cmd_max_sectors == 0) {
 		dec_count(io, region, -EOPNOTSUPP);
 		return;
@@ -328,7 +331,8 @@ static void do_region(int op, int op_flags, unsigned region,
 		/*
 		 * Allocate a suitably sized-bio.
 		 */
-		if ((op == REQ_OP_DISCARD) || (op == REQ_OP_WRITE_SAME))
+		if ((op == REQ_OP_DISCARD) || (op == REQ_OP_WRITE_ZEROES) ||
+		    (op == REQ_OP_WRITE_SAME))
 			num_bvecs = 1;
 		else
 			num_bvecs = min_t(int, BIO_MAX_PAGES,
@@ -341,7 +345,7 @@ static void do_region(int op, int op_flags, unsigned region,
 		bio_set_op_attrs(bio, op, op_flags);
 		store_io_and_region_in_bio(bio, io, region);
 
-		if (op == REQ_OP_DISCARD) {
+		if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) {
 			num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 			remaining -= num_sectors;
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 4788b0b989a9..e17fd44ceef5 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -59,6 +59,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
+	ti->num_write_zeroes_bios = 1;
 	ti->private = lc;
 	return 0;
 
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 7f223dbed49f..ab55955ed704 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1103,6 +1103,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
+	ti->num_write_zeroes_bios = 1;
 	if (m->queue_mode == DM_TYPE_BIO_BASED)
 		ti->per_io_data_size = multipath_per_bio_data_size();
 	else
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 28955b94d2b2..6006d5d4b06e 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -298,9 +298,14 @@ static void dm_done(struct request *clone, int error, bool mapped)
 			r = rq_end_io(tio->ti, clone, error, &tio->info);
 	}
 
-	if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) &&
-		     !clone->q->limits.max_write_same_sectors))
-		disable_write_same(tio->md);
+	if (unlikely(r == -EREMOTEIO)) {
+		if (req_op(clone) == REQ_OP_WRITE_SAME &&
+		    !clone->q->limits.max_write_same_sectors)
+			disable_write_same(tio->md);
+		if (req_op(clone) == REQ_OP_WRITE_ZEROES &&
+		    !clone->q->limits.max_write_zeroes_sectors)
+			disable_write_zeroes(tio->md);
+	}
 
 	if (r <= 0)
 		/* The target wants to complete the I/O */
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 28193a57bf47..5ef49c121d99 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -169,6 +169,7 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->num_flush_bios = stripes;
 	ti->num_discard_bios = stripes;
 	ti->num_write_same_bios = stripes;
+	ti->num_write_zeroes_bios = stripes;
 
 	sc->chunk_size = chunk_size;
 	if (chunk_size & (chunk_size - 1))
@@ -293,6 +294,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 		return DM_MAPIO_REMAPPED;
 	}
 	if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
+	    unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) ||
 	    unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) {
 		target_bio_nr = dm_bio_get_target_bio_nr(bio);
 		BUG_ON(target_bio_nr >= sc->stripes);
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 3ad16d9c9d5a..5cd665c91ead 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1533,6 +1533,34 @@ static bool dm_table_supports_write_same(struct dm_table *t)
 	return true;
 }
 
+static int device_not_write_zeroes_capable(struct dm_target *ti, struct dm_dev *dev,
+					   sector_t start, sector_t len, void *data)
+{
+	struct request_queue *q = bdev_get_queue(dev->bdev);
+
+	return q && !q->limits.max_write_zeroes_sectors;
+}
+
+static bool dm_table_supports_write_zeroes(struct dm_table *t)
+{
+	struct dm_target *ti;
+	unsigned i = 0;
+
+	while (i < dm_table_get_num_targets(t)) {
+		ti = dm_table_get_target(t, i++);
+
+		if (!ti->num_write_zeroes_bios)
+			return false;
+
+		if (!ti->type->iterate_devices ||
+		    ti->type->iterate_devices(ti, device_not_write_zeroes_capable, NULL))
+			return false;
+	}
+
+	return true;
+}
+
+
 static int device_discard_capable(struct dm_target *ti, struct dm_dev *dev,
 				  sector_t start, sector_t len, void *data)
 {
@@ -1603,6 +1631,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 
 	if (!dm_table_supports_write_same(t))
 		q->limits.max_write_same_sectors = 0;
+	if (!dm_table_supports_write_zeroes(t))
+		q->limits.max_write_zeroes_sectors = 0;
 
 	if (dm_table_all_devices_attribute(t, queue_supports_sg_merge))
 		queue_flag_clear_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index dfb75979e455..e8226359c8f7 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -825,6 +825,14 @@ void disable_write_same(struct mapped_device *md)
 	limits->max_write_same_sectors = 0;
 }
 
+void disable_write_zeroes(struct mapped_device *md)
+{
+	struct queue_limits *limits = dm_get_queue_limits(md);
+
+	/* device doesn't really support WRITE ZEROES, disable it */
+	limits->max_write_zeroes_sectors = 0;
+}
+
 static void clone_endio(struct bio *bio)
 {
 	int error = bio->bi_error;
@@ -851,9 +859,14 @@ static void clone_endio(struct bio *bio)
 		}
 	}
 
-	if (unlikely(r == -EREMOTEIO && (bio_op(bio) == REQ_OP_WRITE_SAME) &&
-		     !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors))
-		disable_write_same(md);
+	if (unlikely(r == -EREMOTEIO)) {
+		if (bio_op(bio) == REQ_OP_WRITE_SAME &&
+		    !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors)
+			disable_write_same(md);
+		if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
+		    !bdev_get_queue(bio->bi_bdev)->limits.max_write_zeroes_sectors)
+			disable_write_zeroes(md);
+	}
 
 	free_tio(tio);
 	dec_pending(io, error);
@@ -1202,6 +1215,11 @@ static unsigned get_num_write_same_bios(struct dm_target *ti)
 	return ti->num_write_same_bios;
 }
 
+static unsigned get_num_write_zeroes_bios(struct dm_target *ti)
+{
+	return ti->num_write_zeroes_bios;
+}
+
 typedef bool (*is_split_required_fn)(struct dm_target *ti);
 
 static bool is_split_required_for_discard(struct dm_target *ti)
@@ -1256,6 +1274,11 @@ static int __send_write_same(struct clone_info *ci)
 	return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
 }
 
+static int __send_write_zeroes(struct clone_info *ci)
+{
+	return __send_changing_extent_only(ci, get_num_write_zeroes_bios, NULL);
+}
+
 /*
  * Select the correct strategy for processing a non-flush bio.
  */
@@ -1270,6 +1293,8 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 		return __send_discard(ci);
 	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
 		return __send_write_same(ci);
+	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES))
+		return __send_write_zeroes(ci);
 
 	ti = dm_table_find_target(ci->map, ci->sector);
 	if (!dm_target_is_valid(ti))
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index a7e6903866fd..3829bee2302a 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -255,6 +255,12 @@ struct dm_target {
 	unsigned num_write_same_bios;
 
 	/*
+	 * The number of WRITE ZEROES bios that will be submitted to the target.
+	 * The bio number can be accessed with dm_bio_get_target_bio_nr.
+	 */
+	unsigned num_write_zeroes_bios;
+
+	/*
 	 * The minimum number of extra bytes allocated in each io for the
 	 * target to use.
 	 */
-- 
2.11.0

^ permalink raw reply related

* [PATCH 06/23] dm-kcopyd: switch to use REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

It seems like the code currently passes whatever it was using for writes
to WRITE SAME.  Just switch it to WRITE ZEROES, although that doesn't
need any payload.

Untested, and confused by the code, maybe someone who understands it
better than me can help..

Not-yet-signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/dm-kcopyd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 9e9d04cb7d51..f85846741d50 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -733,11 +733,11 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
 		job->pages = &zero_page_list;
 
 		/*
-		 * Use WRITE SAME to optimize zeroing if all dests support it.
+		 * Use WRITE ZEROES to optimize zeroing if all dests support it.
 		 */
-		job->rw = REQ_OP_WRITE_SAME;
+		job->rw = REQ_OP_WRITE_ZEROES;
 		for (i = 0; i < job->num_dests; i++)
-			if (!bdev_write_same(job->dests[i].bdev)) {
+			if (!bdev_write_zeroes_sectors(job->dests[i].bdev)) {
 				job->rw = WRITE;
 				break;
 			}
-- 
2.11.0


^ permalink raw reply related

* [PATCH 07/23] block: stop using blkdev_issue_write_same for zeroing
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

We'll always use the WRITE ZEROES code for zeroing now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-lib.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index ed1e78e24db0..a93115ccf461 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -364,10 +364,6 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 			return 0;
 	}
 
-	if (!blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
-			ZERO_PAGE(0)))
-		return 0;
-
 	blk_start_plug(&plug);
 	ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
 			&bio, discard);
-- 
2.11.0

^ permalink raw reply related

* [PATCH 08/23] block: add a flags argument to (__)blkdev_issue_zeroout
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Turn the existin discard flag into a new BLKDEV_ZERO_UNMAP flag with
similar semantics, but without referring to diѕcard.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-lib.c              | 31 ++++++++++++++-----------------
 block/ioctl.c                |  3 +--
 drivers/nvme/target/io-cmd.c |  2 +-
 fs/block_dev.c               |  2 +-
 fs/dax.c                     |  2 +-
 fs/xfs/xfs_bmap_util.c       |  2 +-
 include/linux/blkdev.h       | 14 +++++++++-----
 7 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index a93115ccf461..1e849f904d4c 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -282,14 +282,18 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
  * @nr_sects:	number of sectors to write
  * @gfp_mask:	memory allocation flags (for bio_alloc)
  * @biop:	pointer to anchor bio
- * @discard:	discard flag
+ * @flags:	controls detailed behavior
  *
  * Description:
- *  Generate and issue number of bios with zerofiled pages.
+ *  Zero-fill a block range, either using hardware offload or by explicitly
+ *  writing zeroes to the device.
+ *
+ *  If a device is using logical block provisioning, the underlying space will
+ *  only be release if %flags contains BLKDEV_ZERO_UNMAP.
  */
 int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
-		bool discard)
+		unsigned flags)
 {
 	int ret;
 	int bi_size = 0;
@@ -337,28 +341,21 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout);
  * @sector:	start sector
  * @nr_sects:	number of sectors to write
  * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @discard:	whether to discard the block range
+ * @flags:	controls detailed behavior
  *
  * Description:
- *  Zero-fill a block range.  If the discard flag is set and the block
- *  device guarantees that subsequent READ operations to the block range
- *  in question will return zeroes, the blocks will be discarded. Should
- *  the discard request fail, if the discard flag is not set, or if
- *  discard_zeroes_data is not supported, this function will resort to
- *  zeroing the blocks manually, thus provisioning (allocating,
- *  anchoring) them. If the block device supports WRITE ZEROES or WRITE SAME
- *  command(s), blkdev_issue_zeroout() will use it to optimize the process of
- *  clearing the block range. Otherwise the zeroing will be performed
- *  using regular WRITE calls.
+ *  Zero-fill a block range, either using hardware offload or by explicitly
+ *  writing zeroes to the device.  See __blkdev_issue_zeroout() for the
+ *  valid values for %flags.
  */
 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
-			 sector_t nr_sects, gfp_t gfp_mask, bool discard)
+		sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
 {
 	int ret;
 	struct bio *bio = NULL;
 	struct blk_plug plug;
 
-	if (discard) {
+	if (flags & BLKDEV_ZERO_UNMAP) {
 		if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
 				BLKDEV_DISCARD_ZERO))
 			return 0;
@@ -366,7 +363,7 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 
 	blk_start_plug(&plug);
 	ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
-			&bio, discard);
+			&bio, flags);
 	if (ret == 0 && bio) {
 		ret = submit_bio_wait(bio);
 		bio_put(bio);
diff --git a/block/ioctl.c b/block/ioctl.c
index 7b88820b93d9..304685022d9f 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -254,8 +254,7 @@ static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
 	mapping = bdev->bd_inode->i_mapping;
 	truncate_inode_pages_range(mapping, start, end);
 
-	return blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
-				    false);
+	return blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL, 0);
 }
 
 static int put_ushort(unsigned long arg, unsigned short val)
diff --git a/drivers/nvme/target/io-cmd.c b/drivers/nvme/target/io-cmd.c
index 4195115c7e54..1366babaee50 100644
--- a/drivers/nvme/target/io-cmd.c
+++ b/drivers/nvme/target/io-cmd.c
@@ -184,7 +184,7 @@ static void nvmet_execute_write_zeroes(struct nvmet_req *req)
 		(req->ns->blksize_shift - 9)) + 1;
 
 	if (__blkdev_issue_zeroout(req->ns->bdev, sector, nr_sector,
-				GFP_KERNEL, &bio, true))
+				GFP_KERNEL, &bio, BLKDEV_ZERO_UNMAP))
 		status = NVME_SC_INTERNAL | NVME_SC_DNR;
 
 	if (bio) {
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 2eca00ec4370..6128283b7830 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -2110,7 +2110,7 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 	case FALLOC_FL_ZERO_RANGE:
 	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
 		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
-					    GFP_KERNEL, false);
+					    GFP_KERNEL, 0);
 		break;
 	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
 		/* Only punch if the device can do zeroing discard. */
diff --git a/fs/dax.c b/fs/dax.c
index de622d4282a6..7a107355d33f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -982,7 +982,7 @@ int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
 		sector_t start_sector = dax.sector + (offset >> 9);
 
 		return blkdev_issue_zeroout(bdev, start_sector,
-				length >> 9, GFP_NOFS, true);
+				length >> 9, GFP_NOFS, BLKDEV_ZERO_UNMAP);
 	} else {
 		if (dax_map_atomic(bdev, &dax) < 0)
 			return PTR_ERR(dax.addr);
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 8b75dcea5966..6b87c4296787 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -81,7 +81,7 @@ xfs_zero_extent(
 	return blkdev_issue_zeroout(xfs_find_bdev_for_inode(VFS_I(ip)),
 		block << (mp->m_super->s_blocksize_bits - 9),
 		count_fsb << (mp->m_super->s_blocksize_bits - 9),
-		GFP_NOFS, true);
+		GFP_NOFS, BLKDEV_ZERO_UNMAP);
 }
 
 int
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3b3bd646f580..19209416225d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1333,23 +1333,27 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 	return bqt->tag_index[tag];
 }
 
+extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
+extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, struct page *page);
 
 #define BLKDEV_DISCARD_SECURE	(1 << 0)	/* issue a secure erase */
 #define BLKDEV_DISCARD_ZERO	(1 << 1)	/* must reliably zero data */
 
-extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
 extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
 extern int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, int flags,
 		struct bio **biop);
-extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, struct page *page);
+
+#define BLKDEV_ZERO_UNMAP	(1 << 0)  /* free unused blocks */
+
 extern int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
-		bool discard);
+		unsigned flags);
 extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, bool discard);
+		sector_t nr_sects, gfp_t gfp_mask, unsigned flags);
+
 static inline int sb_issue_discard(struct super_block *sb, sector_t block,
 		sector_t nr_blocks, gfp_t gfp_mask, unsigned long flags)
 {
-- 
2.11.0


^ permalink raw reply related

* [PATCH 09/23] block: add a REQ_UNMAP flag for REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

If this flag is set logical provisioning capable device should
release space for the zeroed blocks if possible, if it is not set
devices should keep the blocks anchored.

Also remove an out of sync kerneldoc comment for a static function
that would have become even more out of data with this change.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-lib.c           | 19 +++++--------------
 include/linux/blk_types.h |  5 +++++
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 1e849f904d4c..a59bb54ac7c7 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -226,20 +226,9 @@ int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
 }
 EXPORT_SYMBOL(blkdev_issue_write_same);
 
-/**
- * __blkdev_issue_write_zeroes - generate number of bios with WRITE ZEROES
- * @bdev:	blockdev to issue
- * @sector:	start sector
- * @nr_sects:	number of sectors to write
- * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @biop:	pointer to anchor bio
- *
- * Description:
- *  Generate and issue number of bios(REQ_OP_WRITE_ZEROES) with zerofiled pages.
- */
 static int __blkdev_issue_write_zeroes(struct block_device *bdev,
 		sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
-		struct bio **biop)
+		struct bio **biop, unsigned flags)
 {
 	struct bio *bio = *biop;
 	unsigned int max_write_zeroes_sectors;
@@ -258,7 +247,9 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
 		bio = next_bio(bio, 0, gfp_mask);
 		bio->bi_iter.bi_sector = sector;
 		bio->bi_bdev = bdev;
-		bio_set_op_attrs(bio, REQ_OP_WRITE_ZEROES, 0);
+		bio->bi_opf = REQ_OP_WRITE_ZEROES;
+		if (flags & BLKDEV_ZERO_UNMAP)
+			bio->bi_opf |= REQ_UNMAP;
 
 		if (nr_sects > max_write_zeroes_sectors) {
 			bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
@@ -306,7 +297,7 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		return -EINVAL;
 
 	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
-			biop);
+			biop, flags);
 	if (ret == 0 || (ret && ret != -EOPNOTSUPP))
 		goto out;
 
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 6393c13a6498..4da61fd12c94 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -187,6 +187,10 @@ enum req_flag_bits {
 	__REQ_PREFLUSH,		/* request for cache flush */
 	__REQ_RAHEAD,		/* read ahead, can fail anytime */
 	__REQ_BACKGROUND,	/* background IO */
+
+	/* command specific flags for REQ_OP_WRITE_ZEROES: */
+	__REQ_UNMAP,		/* explicitly release space when zeroing */
+
 	__REQ_NR_BITS,		/* stops here */
 };
 
@@ -203,6 +207,7 @@ enum req_flag_bits {
 #define REQ_PREFLUSH		(1ULL << __REQ_PREFLUSH)
 #define REQ_RAHEAD		(1ULL << __REQ_RAHEAD)
 #define REQ_BACKGROUND		(1ULL << __REQ_BACKGROUND)
+#define REQ_UNMAP		(1ULL << __REQ_UNMAP)
 
 #define REQ_FAILFAST_MASK \
 	(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)
-- 
2.11.0


^ permalink raw reply related

* [PATCH 10/23] block: add a new BLKDEV_ZERO_NOFALLBACK flag
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

This avoids fallbacks to explicit zeroing in (__)blkdev_issue_zeroout if
the caller doesn't want them.

Also clean up the convoluted check for the return condition that this
new flag is added to.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-lib.c        | 5 ++++-
 include/linux/blkdev.h | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index a59bb54ac7c7..33c5bf373b7f 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -281,6 +281,9 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
  *
  *  If a device is using logical block provisioning, the underlying space will
  *  only be release if %flags contains BLKDEV_ZERO_UNMAP.
+ *
+ *  If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
+ *  -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
  */
 int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
@@ -298,7 +301,7 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 
 	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
 			biop, flags);
-	if (ret == 0 || (ret && ret != -EOPNOTSUPP))
+	if (ret != -EOPNOTSUPP || (flags & BLKDEV_ZERO_NOFALLBACK))
 		goto out;
 
 	ret = 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 19209416225d..1bddcfc631a4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1347,6 +1347,7 @@ extern int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		struct bio **biop);
 
 #define BLKDEV_ZERO_UNMAP	(1 << 0)  /* free unused blocks */
+#define BLKDEV_ZERO_NOFALLBACK	(1 << 1)  /* don't write explicit zeroes */
 
 extern int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
-- 
2.11.0

^ permalink raw reply related

* [PATCH 11/23] block_dev: use blkdev_issue_zerout for hole punches
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

This gets us support for non-discard efficient write of zeroes (e.g. NVMe)
and preparse for removing the discard_zeroes_data flag.

Also remove a pointless discard support check, which is done in
blkdev_issue_discard already.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/block_dev.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 6128283b7830..5c701c16e8ff 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -2074,10 +2074,10 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 			     loff_t len)
 {
 	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
-	struct request_queue *q = bdev_get_queue(bdev);
 	struct address_space *mapping;
 	loff_t end = start + len - 1;
 	loff_t isize;
+	unsigned flags = 0;
 	int error;
 
 	/* Fail if we don't recognize the flags. */
@@ -2107,21 +2107,15 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 	truncate_inode_pages_range(mapping, start, end);
 
 	switch (mode) {
+	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
+		flags = BLKDEV_ZERO_NOFALLBACK;
+		/*FALLTHRU*/
 	case FALLOC_FL_ZERO_RANGE:
 	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
 		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
-					    GFP_KERNEL, 0);
-		break;
-	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
-		/* Only punch if the device can do zeroing discard. */
-		if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data)
-			return -EOPNOTSUPP;
-		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
-					     GFP_KERNEL, 0);
+					     GFP_KERNEL, flags);
 		break;
 	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
-		if (!blk_queue_discard(q))
-			return -EOPNOTSUPP;
 		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
 					     GFP_KERNEL, 0);
 		break;
-- 
2.11.0

^ permalink raw reply related

* [PATCH 12/23] sd: handle REQ_UNMAP
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Try to use a write same with unmap bit variant if the device supports it
and the caller asks for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/sd.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b6f70a09a301..ca96bb33471b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -871,6 +871,16 @@ static int sd_setup_write_zeroes_cmnd(struct scsi_cmnd *cmd)
 			return BLKPREP_INVALID;
 		return sd_setup_ata_trim_cmnd(cmd);
 	}
+
+	if (rq->cmd_flags & REQ_UNMAP) {
+		switch (sdkp->provisioning_mode) {
+		case SD_LBP_WS16:
+			return sd_setup_write_same16_cmnd(cmd, true);
+		case SD_LBP_WS10:
+			return sd_setup_write_same10_cmnd(cmd, true);
+		}
+	}
+
 	if (sdp->no_write_same)
 		return BLKPREP_INVALID;
 	if (sdkp->ws16 || sector > 0xffffffff || nr_sectors > 0xffff)
-- 
2.11.0


^ permalink raw reply related

* [PATCH 13/23] nvme: implement REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

But now for the real NVMe Write Zeroes yet, just to get rid of the
discard abuse for zeroing.  Also rename the quirk flag to be a bit
more self-explanatory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/nvme/host/core.c | 10 +++++-----
 drivers/nvme/host/nvme.h |  6 +++---
 drivers/nvme/host/pci.c  |  6 +++---
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 9b3b57fef446..bfa0595dc767 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -335,6 +335,8 @@ int nvme_setup_cmd(struct nvme_ns *ns, struct request *req,
 	case REQ_OP_FLUSH:
 		nvme_setup_flush(ns, cmd);
 		break;
+	case REQ_OP_WRITE_ZEROES:
+		/* currently only aliased to deallocate for a few ctrls: */
 	case REQ_OP_DISCARD:
 		ret = nvme_setup_discard(ns, req, cmd);
 		break;
@@ -900,16 +902,14 @@ static void nvme_config_discard(struct nvme_ns *ns)
 	BUILD_BUG_ON(PAGE_SIZE / sizeof(struct nvme_dsm_range) <
 			NVME_DSM_MAX_RANGES);
 
-	if (ctrl->quirks & NVME_QUIRK_DISCARD_ZEROES)
-		ns->queue->limits.discard_zeroes_data = 1;
-	else
-		ns->queue->limits.discard_zeroes_data = 0;
-
 	ns->queue->limits.discard_alignment = logical_block_size;
 	ns->queue->limits.discard_granularity = logical_block_size;
 	blk_queue_max_discard_sectors(ns->queue, UINT_MAX);
 	blk_queue_max_discard_segments(ns->queue, NVME_DSM_MAX_RANGES);
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, ns->queue);
+
+	if (ctrl->quirks & NVME_QUIRK_DEALLOCATE_ZEROES)
+		blk_queue_max_write_zeroes_sectors(ns->queue, UINT_MAX);
 }
 
 static int nvme_revalidate_ns(struct nvme_ns *ns, struct nvme_id_ns **id)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 2aa20e3e5675..07ebc4a1c8fc 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -68,10 +68,10 @@ enum nvme_quirks {
 	NVME_QUIRK_IDENTIFY_CNS			= (1 << 1),
 
 	/*
-	 * The controller deterministically returns O's on reads to discarded
-	 * logical blocks.
+	 * The controller deterministically returns O's on reads to
+	 * logical blocks that deallocate was called on.
 	 */
-	NVME_QUIRK_DISCARD_ZEROES		= (1 << 2),
+	NVME_QUIRK_DEALLOCATE_ZEROES		= (1 << 2),
 
 	/*
 	 * The controller needs a delay before starts checking the device
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 26a5fd05fe88..0a28787267f0 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2135,13 +2135,13 @@ static const struct pci_error_handlers nvme_err_handler = {
 static const struct pci_device_id nvme_id_table[] = {
 	{ PCI_VDEVICE(INTEL, 0x0953),
 		.driver_data = NVME_QUIRK_STRIPE_SIZE |
-				NVME_QUIRK_DISCARD_ZEROES, },
+				NVME_QUIRK_DEALLOCATE_ZEROES, },
 	{ PCI_VDEVICE(INTEL, 0x0a53),
 		.driver_data = NVME_QUIRK_STRIPE_SIZE |
-				NVME_QUIRK_DISCARD_ZEROES, },
+				NVME_QUIRK_DEALLOCATE_ZEROES, },
 	{ PCI_VDEVICE(INTEL, 0x0a54),
 		.driver_data = NVME_QUIRK_STRIPE_SIZE |
-				NVME_QUIRK_DISCARD_ZEROES, },
+				NVME_QUIRK_DEALLOCATE_ZEROES, },
 	{ PCI_VDEVICE(INTEL, 0x5845),	/* Qemu emulated controller */
 		.driver_data = NVME_QUIRK_IDENTIFY_CNS, },
 	{ PCI_DEVICE(0x1c58, 0x0003),	/* HGST adapter */
-- 
2.11.0


^ permalink raw reply related

* [PATCH 14/23] zram: implement REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Just the same as discard if the block size equals the system page size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/zram/zram_drv.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index dceb5edd1e54..1710b06f04a7 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -829,10 +829,14 @@ static void __zram_make_request(struct zram *zram, struct bio *bio)
 	offset = (bio->bi_iter.bi_sector &
 		  (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
 
-	if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
+	switch (bio_op(bio)) {
+	case REQ_OP_DISCARD:
+	case REQ_OP_WRITE_ZEROES:
 		zram_bio_discard(zram, index, offset, bio);
 		bio_endio(bio);
 		return;
+	default:
+		break;
 	}
 
 	bio_for_each_segment(bvec, bio, iter) {
@@ -1192,6 +1196,8 @@ static int zram_add(void)
 	zram->disk->queue->limits.max_sectors = SECTORS_PER_PAGE;
 	zram->disk->queue->limits.chunk_sectors = 0;
 	blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
+	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
+
 	/*
 	 * zram_bio_discard() will clear all logical blocks if logical block
 	 * size is identical with physical block size(PAGE_SIZE). But if it is
@@ -1201,10 +1207,7 @@ static int zram_add(void)
 	 * zeroed.
 	 */
 	if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
-		zram->disk->queue->limits.discard_zeroes_data = 1;
-	else
-		zram->disk->queue->limits.discard_zeroes_data = 0;
-	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
+		blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
 
 	add_disk(zram->disk);
 
-- 
2.11.0


^ permalink raw reply related

* [PATCH 15/23] loop: implement REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

It's identical to discard as hole punches will always leave us with
zeroes on reads.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/loop.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 0ecb6461ed81..265cd2e33ff0 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -528,6 +528,7 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
 	case REQ_OP_FLUSH:
 		return lo_req_flush(lo, rq);
 	case REQ_OP_DISCARD:
+	case REQ_OP_WRITE_ZEROES:
 		return lo_discard(lo, rq, pos);
 	case REQ_OP_WRITE:
 		if (lo->transfer)
@@ -826,6 +827,7 @@ static void loop_config_discard(struct loop_device *lo)
 		q->limits.discard_granularity = 0;
 		q->limits.discard_alignment = 0;
 		blk_queue_max_discard_sectors(q, 0);
+		blk_queue_max_write_zeroes_sectors(q, 0);
 		q->limits.discard_zeroes_data = 0;
 		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
 		return;
@@ -834,6 +836,7 @@ static void loop_config_discard(struct loop_device *lo)
 	q->limits.discard_granularity = inode->i_sb->s_blocksize;
 	q->limits.discard_alignment = 0;
 	blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
+	blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9);
 	q->limits.discard_zeroes_data = 1;
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 }
@@ -1660,6 +1663,7 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
 	switch (req_op(cmd->rq)) {
 	case REQ_OP_FLUSH:
 	case REQ_OP_DISCARD:
+	case REQ_OP_WRITE_ZEROES:
 		cmd->use_aio = false;
 		break;
 	default:
-- 
2.11.0

^ permalink raw reply related

* [PATCH 16/23] brd: remove discard support
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

It's just a in-driver reimplementation of writing zeroes to the pages,
which fails if the discards aren't page aligned.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/brd.c | 56 -----------------------------------------------------
 1 file changed, 56 deletions(-)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 3adc32a3153b..c15d0581531f 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -134,28 +134,6 @@ static struct page *brd_insert_page(struct brd_device *brd, sector_t sector)
 	return page;
 }
 
-static void brd_free_page(struct brd_device *brd, sector_t sector)
-{
-	struct page *page;
-	pgoff_t idx;
-
-	spin_lock(&brd->brd_lock);
-	idx = sector >> PAGE_SECTORS_SHIFT;
-	page = radix_tree_delete(&brd->brd_pages, idx);
-	spin_unlock(&brd->brd_lock);
-	if (page)
-		__free_page(page);
-}
-
-static void brd_zero_page(struct brd_device *brd, sector_t sector)
-{
-	struct page *page;
-
-	page = brd_lookup_page(brd, sector);
-	if (page)
-		clear_highpage(page);
-}
-
 /*
  * Free all backing store pages and radix tree. This must only be called when
  * there are no other users of the device.
@@ -212,24 +190,6 @@ static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n)
 	return 0;
 }
 
-static void discard_from_brd(struct brd_device *brd,
-			sector_t sector, size_t n)
-{
-	while (n >= PAGE_SIZE) {
-		/*
-		 * Don't want to actually discard pages here because
-		 * re-allocating the pages can result in writeback
-		 * deadlocks under heavy load.
-		 */
-		if (0)
-			brd_free_page(brd, sector);
-		else
-			brd_zero_page(brd, sector);
-		sector += PAGE_SIZE >> SECTOR_SHIFT;
-		n -= PAGE_SIZE;
-	}
-}
-
 /*
  * Copy n bytes from src to the brd starting at sector. Does not sleep.
  */
@@ -338,14 +298,6 @@ static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
 	if (bio_end_sector(bio) > get_capacity(bdev->bd_disk))
 		goto io_error;
 
-	if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
-		if (sector & ((PAGE_SIZE >> SECTOR_SHIFT) - 1) ||
-		    bio->bi_iter.bi_size & ~PAGE_MASK)
-			goto io_error;
-		discard_from_brd(brd, sector, bio->bi_iter.bi_size);
-		goto out;
-	}
-
 	bio_for_each_segment(bvec, bio, iter) {
 		unsigned int len = bvec.bv_len;
 		int err;
@@ -357,9 +309,6 @@ static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
 		sector += len >> SECTOR_SHIFT;
 	}
 
-out:
-	bio_endio(bio);
-	return BLK_QC_T_NONE;
 io_error:
 	bio_io_error(bio);
 	return BLK_QC_T_NONE;
@@ -464,11 +413,6 @@ static struct brd_device *brd_alloc(int i)
 	 *  is harmless)
 	 */
 	blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE);
-
-	brd->brd_queue->limits.discard_granularity = PAGE_SIZE;
-	blk_queue_max_discard_sectors(brd->brd_queue, UINT_MAX);
-	brd->brd_queue->limits.discard_zeroes_data = 1;
-	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);
 #ifdef CONFIG_BLK_DEV_RAM_DAX
 	queue_flag_set_unlocked(QUEUE_FLAG_DAX, brd->brd_queue);
 #endif
-- 
2.11.0

^ permalink raw reply related

* [PATCH 17/23] rbd: remove the discard_zeroes_data flag
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

rbd only supports discarding on large alignments, so the zeroing code
would always fall back to explicit writings of zeroes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/rbd.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 517838b65964..0ec3b430e81d 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4380,7 +4380,6 @@ 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);
-	q->limits.discard_zeroes_data = 1;
 
 	if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC))
 		q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
-- 
2.11.0


^ permalink raw reply related

* [PATCH 18/23] rsxx: remove the discard_zeroes_data flag
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

rsxx only supports discarding on large alignments, so the zeroing code
would always fall back to explicit writings of zeroes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/rsxx/dev.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/block/rsxx/dev.c b/drivers/block/rsxx/dev.c
index f81d70b39d10..9c566364ac9c 100644
--- a/drivers/block/rsxx/dev.c
+++ b/drivers/block/rsxx/dev.c
@@ -300,7 +300,6 @@ int rsxx_setup_dev(struct rsxx_cardinfo *card)
 						RSXX_HW_BLK_SIZE >> 9);
 		card->queue->limits.discard_granularity = RSXX_HW_BLK_SIZE;
 		card->queue->limits.discard_alignment   = RSXX_HW_BLK_SIZE;
-		card->queue->limits.discard_zeroes_data = 1;
 	}
 
 	card->queue->queuedata = card;
-- 
2.11.0

^ permalink raw reply related

* [PATCH 19/23] mmc: remove the discard_zeroes_data flag
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

mmc only supports discarding on large alignments, so the zeroing code
would always fall back to explicit writings of zeroes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/mmc/core/queue.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index 493eb10ce580..4c54ad34e17a 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -167,8 +167,6 @@ static void mmc_queue_setup_discard(struct request_queue *q,
 
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 	blk_queue_max_discard_sectors(q, max_discard);
-	if (card->erased_byte == 0 && !mmc_can_discard(card))
-		q->limits.discard_zeroes_data = 1;
 	q->limits.discard_granularity = card->pref_erase << 9;
 	/* granularity must not be greater than max. discard */
 	if (card->pref_erase > max_discard)
-- 
2.11.0

^ permalink raw reply related

* [PATCH 20/23] block: stop using discards for zeroing
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Now that we have REQ_OP_WRITE_ZEROES implemented for all devices that
support efficient zeroing of devices we can remove the call to
blkdev_issue_discard.  This means we only have two ways of zeroing left
and can simply the code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-lib.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 33c5bf373b7f..153ca59393a7 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -279,6 +279,11 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
  *  Zero-fill a block range, either using hardware offload or by explicitly
  *  writing zeroes to the device.
  *
+ *  Note that this function may fail with -EOPNOTSUPP if the driver supports
+ *  efficient zeroing operation, but the device capabilities can only be
+ *  discovered by trial and error.  In this case the caller should call the
+ *  function again, and it will use the fallback path.
+ *
  *  If a device is using logical block provisioning, the underlying space will
  *  only be release if %flags contains BLKDEV_ZERO_UNMAP.
  *
@@ -349,12 +354,6 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 	struct bio *bio = NULL;
 	struct blk_plug plug;
 
-	if (flags & BLKDEV_ZERO_UNMAP) {
-		if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
-				BLKDEV_DISCARD_ZERO))
-			return 0;
-	}
-
 	blk_start_plug(&plug);
 	ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
 			&bio, flags);
-- 
2.11.0

^ permalink raw reply related

* [PATCH 21/23] drbd: make intelligent use of blkdev_issue_zeroout
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

drbd always wants its discard wire operations to zero the blocks, so
use blkdev_issue_zeroout with the BLKDEV_ZERO_UNMAP flag instead of
reinventing it poorly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/drbd/drbd_debugfs.c  |  3 --
 drivers/block/drbd/drbd_int.h      |  6 ---
 drivers/block/drbd/drbd_receiver.c | 99 ++------------------------------------
 drivers/block/drbd/drbd_req.c      |  6 +--
 4 files changed, 7 insertions(+), 107 deletions(-)

diff --git a/drivers/block/drbd/drbd_debugfs.c b/drivers/block/drbd/drbd_debugfs.c
index de5c3ee8a790..494837e59f23 100644
--- a/drivers/block/drbd/drbd_debugfs.c
+++ b/drivers/block/drbd/drbd_debugfs.c
@@ -236,9 +236,6 @@ static void seq_print_peer_request_flags(struct seq_file *m, struct drbd_peer_re
 	seq_print_rq_state_bit(m, f & EE_CALL_AL_COMPLETE_IO, &sep, "in-AL");
 	seq_print_rq_state_bit(m, f & EE_SEND_WRITE_ACK, &sep, "C");
 	seq_print_rq_state_bit(m, f & EE_MAY_SET_IN_SYNC, &sep, "set-in-sync");
-
-	if (f & EE_IS_TRIM)
-		__seq_print_rq_state_bit(m, f & EE_IS_TRIM_USE_ZEROOUT, &sep, "zero-out", "trim");
 	seq_print_rq_state_bit(m, f & EE_WRITE_SAME, &sep, "write-same");
 	seq_putc(m, '\n');
 }
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 724d1c50fc52..d5da45bb03a6 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -437,9 +437,6 @@ enum {
 
 	/* is this a TRIM aka REQ_DISCARD? */
 	__EE_IS_TRIM,
-	/* our lower level cannot handle trim,
-	 * and we want to fall back to zeroout instead */
-	__EE_IS_TRIM_USE_ZEROOUT,
 
 	/* In case a barrier failed,
 	 * we need to resubmit without the barrier flag. */
@@ -482,7 +479,6 @@ enum {
 #define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
 #define EE_MAY_SET_IN_SYNC     (1<<__EE_MAY_SET_IN_SYNC)
 #define EE_IS_TRIM             (1<<__EE_IS_TRIM)
-#define EE_IS_TRIM_USE_ZEROOUT (1<<__EE_IS_TRIM_USE_ZEROOUT)
 #define EE_RESUBMITTED         (1<<__EE_RESUBMITTED)
 #define EE_WAS_ERROR           (1<<__EE_WAS_ERROR)
 #define EE_HAS_DIGEST          (1<<__EE_HAS_DIGEST)
@@ -1561,8 +1557,6 @@ extern void start_resync_timer_fn(unsigned long data);
 extern void drbd_endio_write_sec_final(struct drbd_peer_request *peer_req);
 
 /* drbd_receiver.c */
-extern int drbd_issue_discard_or_zero_out(struct drbd_device *device,
-		sector_t start, unsigned int nr_sectors, bool discard);
 extern int drbd_receiver(struct drbd_thread *thi);
 extern int drbd_ack_receiver(struct drbd_thread *thi);
 extern void drbd_send_ping_wf(struct work_struct *ws);
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index aa6bf9692eff..8641776f043a 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1448,105 +1448,14 @@ void drbd_bump_write_ordering(struct drbd_resource *resource, struct drbd_backin
 		drbd_info(resource, "Method to ensure write ordering: %s\n", write_ordering_str[resource->write_ordering]);
 }
 
-/*
- * We *may* ignore the discard-zeroes-data setting, if so configured.
- *
- * Assumption is that it "discard_zeroes_data=0" is only because the backend
- * may ignore partial unaligned discards.
- *
- * LVM/DM thin as of at least
- *   LVM version:     2.02.115(2)-RHEL7 (2015-01-28)
- *   Library version: 1.02.93-RHEL7 (2015-01-28)
- *   Driver version:  4.29.0
- * still behaves this way.
- *
- * For unaligned (wrt. alignment and granularity) or too small discards,
- * we zero-out the initial (and/or) trailing unaligned partial chunks,
- * but discard all the aligned full chunks.
- *
- * At least for LVM/DM thin, the result is effectively "discard_zeroes_data=1".
- */
-int drbd_issue_discard_or_zero_out(struct drbd_device *device, sector_t start, unsigned int nr_sectors, bool discard)
-{
-	struct block_device *bdev = device->ldev->backing_bdev;
-	struct request_queue *q = bdev_get_queue(bdev);
-	sector_t tmp, nr;
-	unsigned int max_discard_sectors, granularity;
-	int alignment;
-	int err = 0;
-
-	if (!discard)
-		goto zero_out;
-
-	/* Zero-sector (unknown) and one-sector granularities are the same.  */
-	granularity = max(q->limits.discard_granularity >> 9, 1U);
-	alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
-
-	max_discard_sectors = min(q->limits.max_discard_sectors, (1U << 22));
-	max_discard_sectors -= max_discard_sectors % granularity;
-	if (unlikely(!max_discard_sectors))
-		goto zero_out;
-
-	if (nr_sectors < granularity)
-		goto zero_out;
-
-	tmp = start;
-	if (sector_div(tmp, granularity) != alignment) {
-		if (nr_sectors < 2*granularity)
-			goto zero_out;
-		/* start + gran - (start + gran - align) % gran */
-		tmp = start + granularity - alignment;
-		tmp = start + granularity - sector_div(tmp, granularity);
-
-		nr = tmp - start;
-		err |= blkdev_issue_zeroout(bdev, start, nr, GFP_NOIO, 0);
-		nr_sectors -= nr;
-		start = tmp;
-	}
-	while (nr_sectors >= granularity) {
-		nr = min_t(sector_t, nr_sectors, max_discard_sectors);
-		err |= blkdev_issue_discard(bdev, start, nr, GFP_NOIO, 0);
-		nr_sectors -= nr;
-		start += nr;
-	}
- zero_out:
-	if (nr_sectors) {
-		err |= blkdev_issue_zeroout(bdev, start, nr_sectors, GFP_NOIO, 0);
-	}
-	return err != 0;
-}
-
-static bool can_do_reliable_discards(struct drbd_device *device)
-{
-	struct request_queue *q = bdev_get_queue(device->ldev->backing_bdev);
-	struct disk_conf *dc;
-	bool can_do;
-
-	if (!blk_queue_discard(q))
-		return false;
-
-	if (q->limits.discard_zeroes_data)
-		return true;
-
-	rcu_read_lock();
-	dc = rcu_dereference(device->ldev->disk_conf);
-	can_do = dc->discard_zeroes_if_aligned;
-	rcu_read_unlock();
-	return can_do;
-}
-
 static void drbd_issue_peer_discard(struct drbd_device *device, struct drbd_peer_request *peer_req)
 {
-	/* If the backend cannot discard, or does not guarantee
-	 * read-back zeroes in discarded ranges, we fall back to
-	 * zero-out.  Unless configuration specifically requested
-	 * otherwise. */
-	if (!can_do_reliable_discards(device))
-		peer_req->flags |= EE_IS_TRIM_USE_ZEROOUT;
+	struct block_device *bdev = device->ldev->backing_bdev;
 
-	if (drbd_issue_discard_or_zero_out(device, peer_req->i.sector,
-	    peer_req->i.size >> 9, !(peer_req->flags & EE_IS_TRIM_USE_ZEROOUT)))
+	if (blkdev_issue_zeroout(bdev, peer_req->i.sector, peer_req->i.size >> 9,
+			GFP_NOIO, BLKDEV_ZERO_UNMAP))
 		peer_req->flags |= EE_WAS_ERROR;
+
 	drbd_endio_write_sec_final(peer_req);
 }
 
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 652114ae1a8a..bdd42b8360cc 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1148,10 +1148,10 @@ static int drbd_process_write_request(struct drbd_request *req)
 
 static void drbd_process_discard_req(struct drbd_request *req)
 {
-	int err = drbd_issue_discard_or_zero_out(req->device,
-				req->i.sector, req->i.size >> 9, true);
+	struct block_device *bdev = req->device->ldev->backing_bdev;
 
-	if (err)
+	if (blkdev_issue_zeroout(bdev, req->i.sector, req->i.size >> 9,
+			GFP_NOIO, BLKDEV_ZERO_UNMAP))
 		req->private_bio->bi_error = -EIO;
 	bio_endio(req->private_bio);
 }
-- 
2.11.0

^ permalink raw reply related

* [PATCH 22/23] drbd: implement REQ_OP_WRITE_ZEROES
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

It seems like DRBD assumes its on the wire TRIM request always zeroes data.
Use that fact to implement REQ_OP_WRITE_ZEROES.

XXX: will need a careful audit from the drbd team!

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/drbd/drbd_main.c     | 3 ++-
 drivers/block/drbd/drbd_nl.c       | 2 ++
 drivers/block/drbd/drbd_receiver.c | 6 +++---
 drivers/block/drbd/drbd_req.c      | 7 +++++--
 drivers/block/drbd/drbd_worker.c   | 4 +++-
 5 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 92c60cbd04ee..8e62d9f65510 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -1668,7 +1668,8 @@ static u32 bio_flags_to_wire(struct drbd_connection *connection,
 			(bio->bi_opf & REQ_FUA ? DP_FUA : 0) |
 			(bio->bi_opf & REQ_PREFLUSH ? DP_FLUSH : 0) |
 			(bio_op(bio) == REQ_OP_WRITE_SAME ? DP_WSAME : 0) |
-			(bio_op(bio) == REQ_OP_DISCARD ? DP_DISCARD : 0);
+			(bio_op(bio) == REQ_OP_DISCARD ? DP_DISCARD : 0) |
+			(bio_op(bio) == REQ_OP_WRITE_ZEROES ? DP_DISCARD : 0);
 	else
 		return bio->bi_opf & REQ_SYNC ? DP_RW_SYNC : 0;
 }
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 908c704e20aa..e4516d3b971d 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1217,10 +1217,12 @@ static void decide_on_discard_support(struct drbd_device *device,
 		blk_queue_discard_granularity(q, 512);
 		q->limits.max_discard_sectors = drbd_max_discard_sectors(connection);
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+		q->limits.max_write_zeroes_sectors = drbd_max_discard_sectors(connection);
 	} else {
 		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
 		blk_queue_discard_granularity(q, 0);
 		q->limits.max_discard_sectors = 0;
+		q->limits.max_write_zeroes_sectors = 0;
 	}
 }
 
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 8641776f043a..e64e01ca4d1a 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -2285,7 +2285,7 @@ static unsigned long wire_flags_to_bio_flags(u32 dpf)
 static unsigned long wire_flags_to_bio_op(u32 dpf)
 {
 	if (dpf & DP_DISCARD)
-		return REQ_OP_DISCARD;
+		return REQ_OP_WRITE_ZEROES;
 	else
 		return REQ_OP_WRITE;
 }
@@ -2476,7 +2476,7 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 	op_flags = wire_flags_to_bio_flags(dp_flags);
 	if (pi->cmd == P_TRIM) {
 		D_ASSERT(peer_device, peer_req->i.size > 0);
-		D_ASSERT(peer_device, op == REQ_OP_DISCARD);
+		D_ASSERT(peer_device, op == REQ_OP_WRITE_ZEROES);
 		D_ASSERT(peer_device, peer_req->pages == NULL);
 	} else if (peer_req->pages == NULL) {
 		D_ASSERT(device, peer_req->i.size == 0);
@@ -4789,7 +4789,7 @@ static int receive_rs_deallocated(struct drbd_connection *connection, struct pac
 
 	if (get_ldev(device)) {
 		struct drbd_peer_request *peer_req;
-		const int op = REQ_OP_DISCARD;
+		const int op = REQ_OP_WRITE_ZEROES;
 
 		peer_req = drbd_alloc_peer_req(peer_device, ID_SYNCER, sector,
 					       size, 0, GFP_NOIO);
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index bdd42b8360cc..d76ee53ce528 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -59,6 +59,7 @@ static struct drbd_request *drbd_req_new(struct drbd_device *device, struct bio
 	drbd_req_make_private_bio(req, bio_src);
 	req->rq_state = (bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0)
 		      | (bio_op(bio_src) == REQ_OP_WRITE_SAME ? RQ_WSAME : 0)
+		      | (bio_op(bio_src) == REQ_OP_WRITE_ZEROES ? RQ_UNMAP : 0)
 		      | (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 0);
 	req->device = device;
 	req->master_bio = bio_src;
@@ -1180,7 +1181,8 @@ drbd_submit_req_private_bio(struct drbd_request *req)
 	if (get_ldev(device)) {
 		if (drbd_insert_fault(device, type))
 			bio_io_error(bio);
-		else if (bio_op(bio) == REQ_OP_DISCARD)
+		else if (bio_op(bio) == REQ_OP_WRITE_ZEROES ||
+			 bio_op(bio) == REQ_OP_DISCARD)
 			drbd_process_discard_req(req);
 		else
 			generic_make_request(bio);
@@ -1234,7 +1236,8 @@ drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long
 	_drbd_start_io_acct(device, req);
 
 	/* process discards always from our submitter thread */
-	if (bio_op(bio) & REQ_OP_DISCARD)
+	if ((bio_op(bio) & REQ_OP_WRITE_ZEROES) ||
+	    (bio_op(bio) & REQ_OP_DISCARD))
 		goto queue_for_submitter_thread;
 
 	if (rw == WRITE && req->private_bio && req->i.size
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 3bff33f21435..1afcb4e02d8d 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -174,7 +174,8 @@ void drbd_peer_request_endio(struct bio *bio)
 	struct drbd_peer_request *peer_req = bio->bi_private;
 	struct drbd_device *device = peer_req->peer_device->device;
 	bool is_write = bio_data_dir(bio) == WRITE;
-	bool is_discard = !!(bio_op(bio) == REQ_OP_DISCARD);
+	bool is_discard = bio_op(bio) == REQ_OP_WRITE_ZEROES ||
+			  bio_op(bio) == REQ_OP_DISCARD;
 
 	if (bio->bi_error && __ratelimit(&drbd_ratelimit_state))
 		drbd_warn(device, "%s: error=%d s=%llus\n",
@@ -249,6 +250,7 @@ void drbd_request_endio(struct bio *bio)
 	/* to avoid recursion in __req_mod */
 	if (unlikely(bio->bi_error)) {
 		switch (bio_op(bio)) {
+		case REQ_OP_WRITE_ZEROES:
 		case REQ_OP_DISCARD:
 			if (bio->bi_error == -EOPNOTSUPP)
 				what = DISCARD_COMPLETED_NOTSUPP;
-- 
2.11.0

^ permalink raw reply related

* [PATCH 23/23] block: remove the discard_zeroes_data flag
From: Christoph Hellwig @ 2017-03-23 14:33 UTC (permalink / raw)
  To: axboe, martin.petersen, agk, snitzer, shli, philipp.reisner,
	lars.ellenberg
  Cc: linux-block, linux-scsi, drbd-dev, dm-devel, linux-raid
In-Reply-To: <20170323143341.31549-1-hch@lst.de>

Now that we use the proper REQ_OP_WRITE_ZEROES operation everywhere we can
kill this hack.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/ABI/testing/sysfs-block | 10 ++--------
 Documentation/block/queue-sysfs.txt   |  5 -----
 block/blk-lib.c                       |  7 +------
 block/blk-settings.c                  |  3 ---
 block/blk-sysfs.c                     |  2 +-
 block/compat_ioctl.c                  |  2 +-
 block/ioctl.c                         |  2 +-
 drivers/ata/libata-scsi.c             |  2 +-
 drivers/block/drbd/drbd_main.c        |  2 --
 drivers/block/drbd/drbd_nl.c          |  7 +------
 drivers/block/loop.c                  |  2 --
 drivers/block/mtip32xx/mtip32xx.c     |  1 -
 drivers/block/nbd.c                   |  1 -
 drivers/md/dm-cache-target.c          |  1 -
 drivers/md/dm-crypt.c                 |  1 -
 drivers/md/dm-raid.c                  |  6 +++---
 drivers/md/dm-raid1.c                 |  1 -
 drivers/md/dm-table.c                 | 19 -------------------
 drivers/md/dm-thin.c                  |  2 --
 drivers/md/raid5.c                    | 12 +-----------
 drivers/scsi/sd.c                     |  7 -------
 drivers/target/target_core_device.c   |  2 +-
 include/linux/blkdev.h                | 15 ---------------
 include/linux/device-mapper.h         |  5 -----
 24 files changed, 13 insertions(+), 104 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
index 2da04ce6aeef..dea212db9df3 100644
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -213,14 +213,8 @@ What:		/sys/block/<disk>/queue/discard_zeroes_data
 Date:		May 2011
 Contact:	Martin K. Petersen <martin.petersen@oracle.com>
 Description:
-		Devices that support discard functionality may return
-		stale or random data when a previously discarded block
-		is read back. This can cause problems if the filesystem
-		expects discarded blocks to be explicitly cleared. If a
-		device reports that it deterministically returns zeroes
-		when a discarded area is read the discard_zeroes_data
-		parameter will be set to one. Otherwise it will be 0 and
-		the result of reading a discarded area is undefined.
+		Will always return 0.  Don't rely on any specific behavior
+		for discards, and don't read this file.
 
 What:		/sys/block/<disk>/queue/write_same_max_bytes
 Date:		January 2012
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index c0a3bb5a6e4e..009150ed7db8 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -43,11 +43,6 @@ large discards are issued, setting this value lower will make Linux issue
 smaller discards and potentially help reduce latencies induced by large
 discard operations.
 
-discard_zeroes_data (RO)
-------------------------
-When read, this file will show if the discarded block are zeroed by the
-device or not. If its value is '1' the blocks are zeroed otherwise not.
-
 hw_sector_size (RO)
 -------------------
 This is the hardware sector size of the device, in bytes.
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 153ca59393a7..be44d2725ede 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -37,17 +37,12 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		return -ENXIO;
 
 	if (flags & BLKDEV_DISCARD_SECURE) {
-		if (flags & BLKDEV_DISCARD_ZERO)
-			return -EOPNOTSUPP;
 		if (!blk_queue_secure_erase(q))
 			return -EOPNOTSUPP;
 		op = REQ_OP_SECURE_ERASE;
 	} else {
 		if (!blk_queue_discard(q))
 			return -EOPNOTSUPP;
-		if ((flags & BLKDEV_DISCARD_ZERO) &&
-		    !q->limits.discard_zeroes_data)
-			return -EOPNOTSUPP;
 		op = REQ_OP_DISCARD;
 	}
 
@@ -126,7 +121,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 			&bio);
 	if (!ret && bio) {
 		ret = submit_bio_wait(bio);
-		if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO))
+		if (ret == -EOPNOTSUPP)
 			ret = 0;
 		bio_put(bio);
 	}
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 9d515ae3a405..fe2794986eb9 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -104,7 +104,6 @@ void blk_set_default_limits(struct queue_limits *lim)
 	lim->discard_granularity = 0;
 	lim->discard_alignment = 0;
 	lim->discard_misaligned = 0;
-	lim->discard_zeroes_data = 0;
 	lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
 	lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
 	lim->alignment_offset = 0;
@@ -128,7 +127,6 @@ void blk_set_stacking_limits(struct queue_limits *lim)
 	blk_set_default_limits(lim);
 
 	/* Inherit limits from component devices */
-	lim->discard_zeroes_data = 1;
 	lim->max_segments = USHRT_MAX;
 	lim->max_discard_segments = 1;
 	lim->max_hw_sectors = UINT_MAX;
@@ -623,7 +621,6 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
 	t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
 
 	t->cluster &= b->cluster;
-	t->discard_zeroes_data &= b->discard_zeroes_data;
 
 	/* Physical block size a multiple of the logical block size? */
 	if (t->physical_block_size & (t->logical_block_size - 1)) {
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index c44b321335f3..ca88a533b735 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -208,7 +208,7 @@ static ssize_t queue_discard_max_store(struct request_queue *q,
 
 static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
 {
-	return queue_var_show(queue_discard_zeroes_data(q), page);
+	return 0;
 }
 
 static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 570021a0dc1c..04325b81c2b4 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -685,7 +685,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 	case BLKALIGNOFF:
 		return compat_put_int(arg, bdev_alignment_offset(bdev));
 	case BLKDISCARDZEROES:
-		return compat_put_uint(arg, bdev_discard_zeroes_data(bdev));
+		return compat_put_uint(arg, 0);
 	case BLKFLSBUF:
 	case BLKROSET:
 	case BLKDISCARD:
diff --git a/block/ioctl.c b/block/ioctl.c
index 304685022d9f..1a1586f3baa1 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -546,7 +546,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 	case BLKALIGNOFF:
 		return put_int(arg, bdev_alignment_offset(bdev));
 	case BLKDISCARDZEROES:
-		return put_uint(arg, bdev_discard_zeroes_data(bdev));
+		return put_uint(arg, 0);
 	case BLKSECTGET:
 		max_sectors = min_t(unsigned int, USHRT_MAX,
 				    queue_max_sectors(bdev_get_queue(bdev)));
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 965b9e7dbb7d..6fb870cac932 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1327,7 +1327,7 @@ static int ata_scsi_dev_config(struct scsi_device *sdev,
 		sdev->ata_trim = 1;
 		if (ata_id_has_zero_after_trim(dev->id) &&
 		    (dev->horkage & ATA_HORKAGE_ZERO_AFTER_TRIM)) {
-			ata_dev_info(dev, "Enabling discard_zeroes_data\n");
+			ata_dev_info(dev, "Enabling zeroing using TRIM\n");
 			sdev->ata_trim_zeroes_data = 1;
 		}
 	}
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 8e62d9f65510..84455c365f57 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -931,7 +931,6 @@ void assign_p_sizes_qlim(struct drbd_device *device, struct p_sizes *p, struct r
 		p->qlim->io_min = cpu_to_be32(queue_io_min(q));
 		p->qlim->io_opt = cpu_to_be32(queue_io_opt(q));
 		p->qlim->discard_enabled = blk_queue_discard(q);
-		p->qlim->discard_zeroes_data = queue_discard_zeroes_data(q);
 		p->qlim->write_same_capable = !!q->limits.max_write_same_sectors;
 	} else {
 		q = device->rq_queue;
@@ -941,7 +940,6 @@ void assign_p_sizes_qlim(struct drbd_device *device, struct p_sizes *p, struct r
 		p->qlim->io_min = cpu_to_be32(queue_io_min(q));
 		p->qlim->io_opt = cpu_to_be32(queue_io_opt(q));
 		p->qlim->discard_enabled = 0;
-		p->qlim->discard_zeroes_data = 0;
 		p->qlim->write_same_capable = 0;
 	}
 }
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index e4516d3b971d..02255a0d68b9 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1199,10 +1199,6 @@ static void decide_on_discard_support(struct drbd_device *device,
 	struct drbd_connection *connection = first_peer_device(device)->connection;
 	bool can_do = b ? blk_queue_discard(b) : true;
 
-	if (can_do && b && !b->limits.discard_zeroes_data && !discard_zeroes_if_aligned) {
-		can_do = false;
-		drbd_info(device, "discard_zeroes_data=0 and discard_zeroes_if_aligned=no: disabling discards\n");
-	}
 	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_TRIM)) {
 		can_do = false;
 		drbd_info(connection, "peer DRBD too old, does not support TRIM: disabling discards\n");
@@ -1484,8 +1480,7 @@ static void sanitize_disk_conf(struct drbd_device *device, struct disk_conf *dis
 	if (disk_conf->al_extents > drbd_al_extents_max(nbc))
 		disk_conf->al_extents = drbd_al_extents_max(nbc);
 
-	if (!blk_queue_discard(q)
-	    || (!q->limits.discard_zeroes_data && !disk_conf->discard_zeroes_if_aligned)) {
+	if (!blk_queue_discard(q)) {
 		if (disk_conf->rs_discard_granularity) {
 			disk_conf->rs_discard_granularity = 0; /* disable feature */
 			drbd_info(device, "rs_discard_granularity feature disabled\n");
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 265cd2e33ff0..57f68f4ee886 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -828,7 +828,6 @@ static void loop_config_discard(struct loop_device *lo)
 		q->limits.discard_alignment = 0;
 		blk_queue_max_discard_sectors(q, 0);
 		blk_queue_max_write_zeroes_sectors(q, 0);
-		q->limits.discard_zeroes_data = 0;
 		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
 		return;
 	}
@@ -837,7 +836,6 @@ static void loop_config_discard(struct loop_device *lo)
 	q->limits.discard_alignment = 0;
 	blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
 	blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9);
-	q->limits.discard_zeroes_data = 1;
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 }
 
diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index f96ab717534c..7efac4ee26b2 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -4025,7 +4025,6 @@ static int mtip_block_initialize(struct driver_data *dd)
 		dd->queue->limits.discard_granularity = 4096;
 		blk_queue_max_discard_sectors(dd->queue,
 			MTIP_MAX_TRIM_ENTRY_LEN * MTIP_MAX_TRIM_ENTRIES);
-		dd->queue->limits.discard_zeroes_data = 0;
 	}
 
 	/* Set the capacity of the device in 512 byte sectors. */
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7e4287bc19e5..616e5c6d3ebd 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1040,7 +1040,6 @@ static int nbd_dev_add(int index)
 	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue);
 	disk->queue->limits.discard_granularity = 512;
 	blk_queue_max_discard_sectors(disk->queue, UINT_MAX);
-	disk->queue->limits.discard_zeroes_data = 0;
 	blk_queue_max_hw_sectors(disk->queue, 65536);
 	disk->queue->limits.max_sectors = 256;
 
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 9c689b34e6e7..975922c8f231 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2773,7 +2773,6 @@ static int cache_create(struct cache_args *ca, struct cache **result)
 
 	ti->num_discard_bios = 1;
 	ti->discards_supported = true;
-	ti->discard_zeroes_data_unsupported = true;
 	ti->split_discard_bios = false;
 
 	cache->features = ca->features;
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 389a3637ffcc..ef1d836bd81b 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2030,7 +2030,6 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	wake_up_process(cc->write_thread);
 
 	ti->num_flush_bios = 1;
-	ti->discard_zeroes_data_unsupported = true;
 
 	return 0;
 
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index f8564d63982f..468f1380de1d 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -2813,7 +2813,9 @@ static void configure_discard_support(struct raid_set *rs)
 	/* Assume discards not supported until after checks below. */
 	ti->discards_supported = false;
 
-	/* RAID level 4,5,6 require discard_zeroes_data for data integrity! */
+	/*
+	 * XXX: RAID level 4,5,6 require zeroing for safety.
+	 */
 	raid456 = (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6);
 
 	for (i = 0; i < rs->raid_disks; i++) {
@@ -2827,8 +2829,6 @@ static void configure_discard_support(struct raid_set *rs)
 			return;
 
 		if (raid456) {
-			if (!q->limits.discard_zeroes_data)
-				return;
 			if (!devices_handle_discard_safely) {
 				DMERR("raid456 discard support disabled due to discard_zeroes_data uncertainty.");
 				DMERR("Set dm-raid.devices_handle_discard_safely=Y to override.");
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 2ddc2d20e62d..a95cbb80fb34 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1124,7 +1124,6 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->per_io_data_size = sizeof(struct dm_raid1_bio_record);
-	ti->discard_zeroes_data_unsupported = true;
 
 	ms->kmirrord_wq = alloc_workqueue("kmirrord", WQ_MEM_RECLAIM, 0);
 	if (!ms->kmirrord_wq) {
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 5cd665c91ead..958275aca008 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1449,22 +1449,6 @@ static bool dm_table_supports_flush(struct dm_table *t, unsigned long flush)
 	return false;
 }
 
-static bool dm_table_discard_zeroes_data(struct dm_table *t)
-{
-	struct dm_target *ti;
-	unsigned i = 0;
-
-	/* Ensure that all targets supports discard_zeroes_data. */
-	while (i < dm_table_get_num_targets(t)) {
-		ti = dm_table_get_target(t, i++);
-
-		if (ti->discard_zeroes_data_unsupported)
-			return false;
-	}
-
-	return true;
-}
-
 static int device_is_nonrot(struct dm_target *ti, struct dm_dev *dev,
 			    sector_t start, sector_t len, void *data)
 {
@@ -1620,9 +1604,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	}
 	blk_queue_write_cache(q, wc, fua);
 
-	if (!dm_table_discard_zeroes_data(t))
-		q->limits.discard_zeroes_data = 0;
-
 	/* Ensure that all underlying devices are non-rotational. */
 	if (dm_table_all_devices_attribute(t, device_is_nonrot))
 		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 2b266a2b5035..a5f1916f621a 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -3263,7 +3263,6 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	 * them down to the data device.  The thin device's discard
 	 * processing will cause mappings to be removed from the btree.
 	 */
-	ti->discard_zeroes_data_unsupported = true;
 	if (pf.discard_enabled && pf.discard_passdown) {
 		ti->num_discard_bios = 1;
 
@@ -4119,7 +4118,6 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	ti->per_io_data_size = sizeof(struct dm_thin_endio_hook);
 
 	/* In case the pool supports discards, pass them on. */
-	ti->discard_zeroes_data_unsupported = true;
 	if (tc->pool->pf.discard_enabled) {
 		ti->discards_supported = true;
 		ti->num_discard_bios = 1;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 8cf1f86dcd05..a4b04d0dc829 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7265,12 +7265,6 @@ static int raid5_run(struct mddev *mddev)
 		blk_queue_max_discard_sectors(mddev->queue,
 					      0xfffe * STRIPE_SECTORS);
 
-		/*
-		 * unaligned part of discard request will be ignored, so can't
-		 * guarantee discard_zeroes_data
-		 */
-		mddev->queue->limits.discard_zeroes_data = 0;
-
 		blk_queue_max_write_same_sectors(mddev->queue, 0);
 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
 
@@ -7280,7 +7274,7 @@ static int raid5_run(struct mddev *mddev)
 			disk_stack_limits(mddev->gendisk, rdev->bdev,
 					  rdev->new_data_offset << 9);
 			/*
-			 * discard_zeroes_data is required, otherwise data
+			 * zeroing is required, otherwise data
 			 * could be lost. Consider a scenario: discard a stripe
 			 * (the stripe could be inconsistent if
 			 * discard_zeroes_data is 0); write one disk of the
@@ -7289,10 +7283,6 @@ static int raid5_run(struct mddev *mddev)
 			 * parity); the disk is broken; The stripe data of this
 			 * disk is lost.
 			 */
-			if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
-			    !bdev_get_queue(rdev->bdev)->
-						limits.discard_zeroes_data)
-				discard_supported = false;
 			/* Unfortunately, discard_zeroes_data is not currently
 			 * a guarantee - just a hint.  So we only allow DISCARD
 			 * if the sysadmin has confirmed that only safe devices
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index ca96bb33471b..65ed02438565 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -645,8 +645,6 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
 	unsigned int logical_block_size = sdkp->device->sector_size;
 	unsigned int max_blocks = 0, max_ranges = 0, max_range_size = 0;
 
-	q->limits.discard_zeroes_data = 0;
-
 	/*
 	 * When LBPRZ is reported, discard alignment and granularity
 	 * must be fixed to the logical block size. Otherwise the block
@@ -682,27 +680,22 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
 	case SD_LBP_WS16:
 		max_blocks = min_not_zero(sdkp->max_ws_blocks,
 					  (u32)SD_MAX_WS16_BLOCKS);
-		q->limits.discard_zeroes_data = sdkp->lbprz;
 		break;
 
 	case SD_LBP_WS10:
 		max_blocks = min_not_zero(sdkp->max_ws_blocks,
 					  (u32)SD_MAX_WS10_BLOCKS);
-		q->limits.discard_zeroes_data = sdkp->lbprz;
 		break;
 
 	case SD_LBP_ZERO:
 		max_blocks = min_not_zero(sdkp->max_ws_blocks,
 					  (u32)SD_MAX_WS10_BLOCKS);
-		q->limits.discard_zeroes_data = 1;
 		break;
 
 	case SD_LBP_ATA_TRIM:
 		max_ranges = 512 / sizeof(__le64);
 		max_range_size = USHRT_MAX;
 		max_blocks = max_ranges * max_range_size;
-		if (sdkp->device->ata_trim_zeroes_data)
-			q->limits.discard_zeroes_data = 1;
 		break;
 	}
 
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index c754ae33bf7b..d2f089cfa9ae 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -851,7 +851,7 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
 	attrib->unmap_granularity = q->limits.discard_granularity / block_size;
 	attrib->unmap_granularity_alignment = q->limits.discard_alignment /
 								block_size;
-	attrib->unmap_zeroes_data = q->limits.discard_zeroes_data;
+	attrib->unmap_zeroes_data = 0;
 	return true;
 }
 EXPORT_SYMBOL(target_configure_unmap_from_queue);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1bddcfc631a4..aa1ac2c0f393 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -338,7 +338,6 @@ struct queue_limits {
 	unsigned char		misaligned;
 	unsigned char		discard_misaligned;
 	unsigned char		cluster;
-	unsigned char		discard_zeroes_data;
 	unsigned char		raid_partial_stripes_expensive;
 	enum blk_zoned_model	zoned;
 };
@@ -1338,7 +1337,6 @@ extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, struct page *page);
 
 #define BLKDEV_DISCARD_SECURE	(1 << 0)	/* issue a secure erase */
-#define BLKDEV_DISCARD_ZERO	(1 << 1)	/* must reliably zero data */
 
 extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
@@ -1543,19 +1541,6 @@ static inline int bdev_discard_alignment(struct block_device *bdev)
 	return q->limits.discard_alignment;
 }
 
-static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
-{
-	if (q->limits.max_discard_sectors && q->limits.discard_zeroes_data == 1)
-		return 1;
-
-	return 0;
-}
-
-static inline unsigned int bdev_discard_zeroes_data(struct block_device *bdev)
-{
-	return queue_discard_zeroes_data(bdev_get_queue(bdev));
-}
-
 static inline unsigned int bdev_write_same(struct block_device *bdev)
 {
 	struct request_queue *q = bdev_get_queue(bdev);
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 3829bee2302a..c7ea33e38fb9 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -296,11 +296,6 @@ struct dm_target {
 	 * on max_io_len boundary.
 	 */
 	bool split_discard_bios:1;
-
-	/*
-	 * Set if this target does not return zeroes on discarded blocks.
-	 */
-	bool discard_zeroes_data_unsupported:1;
 };
 
 /* Each target can link one of these into the table */
-- 
2.11.0

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