[PATCH] nbd: set discard granularity properly

[PATCH] nbd: set discard granularity properly

[Josef Bacik]

From: Josef Bacik <jbacik@fb.com>

For some reason we had discard granularity set to 512 always even when
discards were disabled.  Fix this by having the default be 0, and then
if we turn it on set the discard granularity to the blocksize.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
---
 drivers/block/nbd.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 1147e4680c80..bdfbb2a7018c 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -236,6 +236,10 @@ static void nbd_size_update(struct nbd_device *nbd)
 	struct nbd_config *config = nbd->config;
 	struct block_device *bdev = bdget_disk(nbd->disk, 0);
 
+	if (config->flags & NBD_FLAG_SEND_TRIM) {
+		nbd->disk->queue->limits.discard_granularity = config->blksize;
+		blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
+	}
 	blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 	blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 	set_capacity(nbd->disk, config->bytesize >> 9);
@@ -1050,6 +1054,8 @@ static void nbd_config_put(struct nbd_device *nbd)
 		nbd->config = NULL;
 
 		nbd->tag_set.timeout = 0;
+		nbd->disk->queue->limits.discard_granularity = 0;
+		blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
 		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 
 		mutex_unlock(&nbd->config_lock);
@@ -1502,8 +1508,8 @@ static int nbd_dev_add(int index)
 	 */
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
 	blk_queue_flag_clear(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_granularity = 0;
+	blk_queue_max_discard_sectors(disk->queue, 0);
 	blk_queue_max_segment_size(disk->queue, UINT_MAX);
 	blk_queue_max_segments(disk->queue, USHRT_MAX);
 	blk_queue_max_hw_sectors(disk->queue, 65536);
-- 
2.14.3

Re: [PATCH] nbd: set discard granularity properly

[Jens Axboe]

On 5/23/18 11:35 AM, Josef Bacik wrote:
> From: Josef Bacik <jbacik@fb.com>
> 
> For some reason we had discard granularity set to 512 always even when
> discards were disabled.  Fix this by having the default be 0, and then
> if we turn it on set the discard granularity to the blocksize.

Applied, thanks.

-- 
Jens Axboe

Re: [PATCH] nbd: set discard granularity properly

[Martin K. Petersen]

Josef,

> For some reason we had discard granularity set to 512 always even when
> discards were disabled.  Fix this by having the default be 0, and then
> if we turn it on set the discard granularity to the blocksize.

Originally, discard_max_bytes was the queue limit used to indicate
whether discards were supported or not. Callers were supposed to check
that for a value bigger than 0 before interpreting granularity and
alignment. However, many callers triggered on discard_granularity > 0
instead, and as a result things have been muddled somewhat.

So I don't have a problem with only reporting granularity when the
feature is actually enabled...

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering

[PATCH] nbd: set discard granularity properly

[Josef Bacik]

From: Josef Bacik <jbacik@fb.com>

For some reason we had discard granularity set to 512 always even when
discards were disabled.  Fix this by having the default be 0, and then
if we turn it on set the discard granularity to the blocksize.

Signed-off-by: Josef Bacik <jbacik@fb.com>
---
 drivers/block/nbd.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 5f2a4240a204..32b6f66ea5bf 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -231,6 +231,11 @@ static void nbd_size_clear(struct nbd_device *nbd)
 static void nbd_size_update(struct nbd_device *nbd)
 {
 	struct nbd_config *config = nbd->config;
+
+	if (config->flags & NBD_FLAG_SEND_TRIM) {
+		nbd->disk->queue->limits.discard_granularity = config->blksize;
+		blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
+	}
 	blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 	blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 	set_capacity(nbd->disk, config->bytesize >> 9);
@@ -1040,6 +1045,8 @@ static void nbd_config_put(struct nbd_device *nbd)
 		nbd->config = NULL;
 
 		nbd->tag_set.timeout = 0;
+		nbd->disk->queue->limits.discard_granularity = 0;
+		blk_queue_max_discard_sectors(nbd->disk->queue, 0);
 		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 
 		mutex_unlock(&nbd->config_lock);
@@ -1490,8 +1497,8 @@ static int nbd_dev_add(int index)
 	 */
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
 	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_granularity = 0;
+	blk_queue_max_discard_sectors(disk->queue, 0);
 	blk_queue_max_segment_size(disk->queue, UINT_MAX);
 	blk_queue_max_segments(disk->queue, USHRT_MAX);
 	blk_queue_max_hw_sectors(disk->queue, 65536);
-- 
2.7.5