block: move the add_random flag to queue_limits

Move the add_random flag into the queue_limits feature field so that it
can be set atomically with the queue frozen.

Note that this also removes code from dm to clear the flag based on
the underlying devices, which can't be reached as dm devices will
always start out without the flag set.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240617060532.127975-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

7 files changed, 4 insertions, 38 deletions

diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index 1dbbf72659d5..c6ef0546ffc9 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -3485,7 +3485,6 @@ skip_create_disk:
 		goto start_service_thread;
 
 	/* Set device limits. */
-	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, dd->queue);
 	dma_set_max_seg_size(&dd->pdev->dev, 0x400000);
 
 	/* Set the capacity of the device in 512 byte sectors. */
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index c062af329709..0a3838e45aff 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1716,14 +1716,6 @@ static int device_dax_write_cache_enabled(struct dm_target *ti,
 	return false;
 }
 
-static int device_is_not_random(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 !blk_queue_add_random(q);
-}
-
 static int device_not_write_zeroes_capable(struct dm_target *ti, struct dm_dev *dev,
 					   sector_t start, sector_t len, void *data)
 {
@@ -1877,16 +1869,6 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 		blk_queue_flag_clear(QUEUE_FLAG_STABLE_WRITES, q);
 
 	/*
-	 * Determine whether or not this queue's I/O timings contribute
-	 * to the entropy pool, Only request-based targets use this.
-	 * Clear QUEUE_FLAG_ADD_RANDOM if any underlying device does not
-	 * have it set.
-	 */
-	if (blk_queue_add_random(q) &&
-	    dm_table_any_dev_attr(t, device_is_not_random, NULL))
-		blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, q);
-
-	/*
 	 * For a zoned target, setup the zones related queue attributes
 	 * and resources necessary for zone append emulation if necessary.
 	 */
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index b4f62fa84586..da00904d4a3c 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -387,8 +387,6 @@ static struct gendisk *mmc_alloc_disk(struct mmc_queue *mq,
 		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, mq->queue);
 	blk_queue_rq_timeout(mq->queue, 60 * HZ);
 
-	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue);
-
 	dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
 
 	INIT_WORK(&mq->recovery_work, mmc_mq_recovery_handler);
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index bf8369ce7ddf..47ead84407cd 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -374,9 +374,6 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	/* Create the request queue */
 	spin_lock_init(&new->queue_lock);
 	INIT_LIST_HEAD(&new->rq_list);
-
-	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
-
 	gd->queue = new->rq;
 
 	if (new->readonly)
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index 2e2309fa9a0b..3fcfe029db1b 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -439,7 +439,6 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
 		.logical_block_size	= 1 << 12,
 	};
 	unsigned int devindex;
-	struct request_queue *rq;
 	int len, ret;
 
 	lim.max_segments = min(scmdev->nr_max_block,
@@ -474,9 +473,6 @@ int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
 		ret = PTR_ERR(bdev->gendisk);
 		goto out_tag;
 	}
-	rq = bdev->rq = bdev->gendisk->queue;
-	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, rq);
-
 	bdev->gendisk->private_data = scmdev;
 	bdev->gendisk->fops = &scm_blk_devops;
 	bdev->gendisk->major = scm_major;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ec39acc986d6..54f771ec8cfb 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -631,8 +631,7 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
 	if (blk_update_request(req, error, bytes))
 		return true;
 
-	// XXX:
-	if (blk_queue_add_random(q))
+	if (q->limits.features & BLK_FEAT_ADD_RANDOM)
 		add_disk_randomness(req->q->disk);
 
 	WARN_ON_ONCE(!blk_rq_is_passthrough(req) &&
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a42c3c45e868..a27f1c7f1b61 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3301,7 +3301,6 @@ static void sd_read_block_limits_ext(struct scsi_disk *sdkp)
 static void sd_read_block_characteristics(struct scsi_disk *sdkp,
 		struct queue_limits *lim)
 {
-	struct request_queue *q = sdkp->disk->queue;
 	struct scsi_vpd *vpd;
 	u16 rot;
 
@@ -3317,10 +3316,8 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp,
 	sdkp->zoned = (vpd->data[8] >> 4) & 3;
 	rcu_read_unlock();
 
-	if (rot == 1) {
-		lim->features &= ~BLK_FEAT_ROTATIONAL;
-		blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, q);
-	}
+	if (rot == 1)
+		lim->features &= ~(BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM);
 
 	if (!sdkp->first_scan)
 		return;
@@ -3599,7 +3596,6 @@ static int sd_revalidate_disk(struct gendisk *disk)
 {
 	struct scsi_disk *sdkp = scsi_disk(disk);
 	struct scsi_device *sdp = sdkp->device;
-	struct request_queue *q = sdkp->disk->queue;
 	sector_t old_capacity = sdkp->capacity;
 	struct queue_limits lim;
 	unsigned char *buffer;
@@ -3646,8 +3642,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 		 * cause this to be updated correctly and any device which
 		 * doesn't support it should be treated as rotational.
 		 */
-		lim.features |= BLK_FEAT_ROTATIONAL;
-		blk_queue_flag_set(QUEUE_FLAG_ADD_RANDOM, q);
+		lim.features |= (BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM);
 
 		if (scsi_device_supports_vpd(sdp)) {
 			sd_read_block_provisioning(sdkp);