block: move the stable_writes flag to queue_limits

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

The flag is now inherited by blk_stack_limits, which greatly simplifies
the code in dm, and fixed md which previously did not pass on the flag
set on lower devices.
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/20240617060532.127975-18-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-debugfs.c

@@ -88,7 +88,6 @@ static const char *const blk_queue_flag_name[] = {
 	QUEUE_FLAG_NAME(SYNCHRONOUS),
 	QUEUE_FLAG_NAME(SAME_FORCE),
 	QUEUE_FLAG_NAME(INIT_DONE),
-	QUEUE_FLAG_NAME(STABLE_WRITES),
 	QUEUE_FLAG_NAME(POLL),
 	QUEUE_FLAG_NAME(DAX),
 	QUEUE_FLAG_NAME(STATS),

block/blk-sysfs.c

@@ -296,37 +296,10 @@ static ssize_t queue_##_name##_store(struct request_queue *q,		 \
 	return queue_feature_store(q, page, count, _feature);		 \
 }
 
-#define QUEUE_SYSFS_BIT_FNS(name, flag, neg)				\
-static ssize_t								\
-queue_##name##_show(struct request_queue *q, char *page)		\
-{									\
-	int bit;							\
-	bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags);		\
-	return queue_var_show(neg ? !bit : bit, page);			\
-}									\
-static ssize_t								\
-queue_##name##_store(struct request_queue *q, const char *page, size_t count) \
-{									\
-	unsigned long val;						\
-	ssize_t ret;							\
-	ret = queue_var_store(&val, page, count);			\
-	if (ret < 0)							\
-		 return ret;						\
-	if (neg)							\
-		val = !val;						\
-									\
-	if (val)							\
-		blk_queue_flag_set(QUEUE_FLAG_##flag, q);		\
-	else								\
-		blk_queue_flag_clear(QUEUE_FLAG_##flag, q);		\
-	return ret;							\
-}
-
 QUEUE_SYSFS_FEATURE(rotational, BLK_FEAT_ROTATIONAL)
 QUEUE_SYSFS_FEATURE(add_random, BLK_FEAT_ADD_RANDOM)
 QUEUE_SYSFS_FEATURE(iostats, BLK_FEAT_IO_STAT)
-QUEUE_SYSFS_BIT_FNS(stable_writes, STABLE_WRITES, 0);
-#undef QUEUE_SYSFS_BIT_FNS
+QUEUE_SYSFS_FEATURE(stable_writes, BLK_FEAT_STABLE_WRITES);
 
 static ssize_t queue_zoned_show(struct request_queue *q, char *page)
 {

drivers/block/drbd/drbd_main.c

@@ -2698,7 +2698,8 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 		 */
 		.max_hw_sectors		= DRBD_MAX_BIO_SIZE_SAFE >> 8,
 		.features		= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA |
-					  BLK_FEAT_ROTATIONAL,
+					  BLK_FEAT_ROTATIONAL |
+					  BLK_FEAT_STABLE_WRITES,
 	};
 
 	device = minor_to_device(minor);
@@ -2737,8 +2738,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 	sprintf(disk->disk_name, "drbd%d", minor);
 	disk->private_data = device;
 
-	blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, disk->queue);
-
 	device->md_io.page = alloc_page(GFP_KERNEL);
 	if (!device->md_io.page)
 		goto out_no_io_page;

drivers/block/rbd.c

@@ -4949,7 +4949,6 @@ static const struct blk_mq_ops rbd_mq_ops = {
 static int rbd_init_disk(struct rbd_device *rbd_dev)
 {
 	struct gendisk *disk;
-	struct request_queue *q;
 	unsigned int objset_bytes =
 	    rbd_dev->layout.object_size * rbd_dev->layout.stripe_count;
 	struct queue_limits lim = {
@@ -4979,12 +4978,14 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 		lim.max_write_zeroes_sectors = objset_bytes >> SECTOR_SHIFT;
 	}
 
+	if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC))
+		lim.features |= BLK_FEAT_STABLE_WRITES;
+
 	disk = blk_mq_alloc_disk(&rbd_dev->tag_set, &lim, rbd_dev);
 	if (IS_ERR(disk)) {
 		err = PTR_ERR(disk);
 		goto out_tag_set;
 	}
-	q = disk->queue;
 
 	snprintf(disk->disk_name, sizeof(disk->disk_name), RBD_DRV_NAME "%d",
 		 rbd_dev->dev_id);
@@ -4996,10 +4997,6 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 		disk->minors = RBD_MINORS_PER_MAJOR;
 	disk->fops = &rbd_bd_ops;
 	disk->private_data = rbd_dev;
-
-	if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC))
-		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q);
-
 	rbd_dev->disk = disk;
 
 	return 0;

drivers/block/zram/zram_drv.c

@@ -2208,6 +2208,7 @@ static int zram_add(void)
 #if ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE
 		.max_write_zeroes_sectors	= UINT_MAX,
 #endif
+		.features			= BLK_FEAT_STABLE_WRITES,
 	};
 	struct zram *zram;
 	int ret, device_id;
@@ -2246,7 +2247,6 @@ static int zram_add(void)
 	/* Actual capacity set using sysfs (/sys/block/zram<id>/disksize */
 	set_capacity(zram->disk, 0);
 	blk_queue_flag_set(QUEUE_FLAG_SYNCHRONOUS, zram->disk->queue);
-	blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, zram->disk->queue);
 	ret = device_add_disk(NULL, zram->disk, zram_disk_groups);
 	if (ret)
 		goto out_cleanup_disk;

drivers/md/dm-table.c

@@ -1819,13 +1819,6 @@ static bool dm_table_supports_secure_erase(struct dm_table *t)
 	return true;
 }
 
-static int device_requires_stable_pages(struct dm_target *ti,
-					struct dm_dev *dev, sector_t start,
-					sector_t len, void *data)
-{
-	return bdev_stable_writes(dev->bdev);
-}
-
 int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 			      struct queue_limits *limits)
 {
@@ -1862,18 +1855,6 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	if (dm_table_any_dev_attr(t, device_dax_write_cache_enabled, NULL))
 		dax_write_cache(t->md->dax_dev, true);
 
-	/*
-	 * Some devices don't use blk_integrity but still want stable pages
-	 * because they do their own checksumming.
-	 * If any underlying device requires stable pages, a table must require
-	 * them as well.  Only targets that support iterate_devices are considered:
-	 * don't want error, zero, etc to require stable pages.
-	 */
-	if (dm_table_any_dev_attr(t, device_requires_stable_pages, NULL))
-		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q);
-	else
-		blk_queue_flag_clear(QUEUE_FLAG_STABLE_WRITES, q);
-
 	/*
 	 * For a zoned target, setup the zones related queue attributes
 	 * and resources necessary for zone append emulation if necessary.

drivers/md/raid5.c

@@ -7082,12 +7082,14 @@ raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
 		err = -ENODEV;
 	else if (new != conf->skip_copy) {
 		struct request_queue *q = mddev->gendisk->queue;
+		struct queue_limits lim = queue_limits_start_update(q);
 
 		conf->skip_copy = new;
 		if (new)
-			blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q);
+			lim.features |= BLK_FEAT_STABLE_WRITES;
 		else
-			blk_queue_flag_clear(QUEUE_FLAG_STABLE_WRITES, q);
+			lim.features &= ~BLK_FEAT_STABLE_WRITES;
+		err = queue_limits_commit_update(q, &lim);
 	}
 	mddev_unlock_and_resume(mddev);
 	return err ?: len;

drivers/mmc/core/queue.c

@@ -378,13 +378,14 @@ static struct gendisk *mmc_alloc_disk(struct mmc_queue *mq,
 		lim.max_segments = host->max_segs;
 	}
 
+	if (mmc_host_is_spi(host) && host->use_spi_crc)
+		lim.features |= BLK_FEAT_STABLE_WRITES;
+
 	disk = blk_mq_alloc_disk(&mq->tag_set, &lim, mq);
 	if (IS_ERR(disk))
 		return disk;
 	mq->queue = disk->queue;
 
-	if (mmc_host_is_spi(host) && host->use_spi_crc)
-		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, mq->queue);
 	blk_queue_rq_timeout(mq->queue, 60 * HZ);
 
 	dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));

drivers/nvme/host/core.c

@@ -3724,6 +3724,7 @@ static void nvme_ns_add_to_ctrl_list(struct nvme_ns *ns)
 
 static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
 {
+	struct queue_limits lim = { };
 	struct nvme_ns *ns;
 	struct gendisk *disk;
 	int node = ctrl->numa_node;
@@ -3732,7 +3733,10 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
 	if (!ns)
 		return;
 
-	disk = blk_mq_alloc_disk(ctrl->tagset, NULL, ns);
+	if (ctrl->opts && ctrl->opts->data_digest)
+		lim.features |= BLK_FEAT_STABLE_WRITES;
+
+	disk = blk_mq_alloc_disk(ctrl->tagset, &lim, ns);
 	if (IS_ERR(disk))
 		goto out_free_ns;
 	disk->fops = &nvme_bdev_ops;
@@ -3741,9 +3745,6 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
 	ns->disk = disk;
 	ns->queue = disk->queue;
 
-	if (ctrl->opts && ctrl->opts->data_digest)
-		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, ns->queue);
-
 	if (ctrl->ops->supports_pci_p2pdma &&
 	    ctrl->ops->supports_pci_p2pdma(ctrl))
 		blk_queue_flag_set(QUEUE_FLAG_PCI_P2PDMA, ns->queue);

drivers/nvme/host/multipath.c

@@ -868,10 +868,6 @@ void nvme_mpath_add_disk(struct nvme_ns *ns, __le32 anagrpid)
 		nvme_mpath_set_live(ns);
 	}
 
-	if (test_bit(QUEUE_FLAG_STABLE_WRITES, &ns->queue->queue_flags) &&
-	    ns->head->disk)
-		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES,
-				   ns->head->disk->queue);
 #ifdef CONFIG_BLK_DEV_ZONED
 	if (blk_queue_is_zoned(ns->queue) && ns->head->disk)
 		ns->head->disk->nr_zones = ns->disk->nr_zones;

drivers/scsi/iscsi_tcp.c

@@ -1057,15 +1057,15 @@ static umode_t iscsi_sw_tcp_attr_is_visible(int param_type, int param)
 	return 0;
 }
 
-static int iscsi_sw_tcp_slave_configure(struct scsi_device *sdev)
+static int iscsi_sw_tcp_device_configure(struct scsi_device *sdev,
+		struct queue_limits *lim)
 {
 	struct iscsi_sw_tcp_host *tcp_sw_host = iscsi_host_priv(sdev->host);
 	struct iscsi_session *session = tcp_sw_host->session;
 	struct iscsi_conn *conn = session->leadconn;
 
 	if (conn->datadgst_en)
-		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES,
-				   sdev->request_queue);
+		lim->features |= BLK_FEAT_STABLE_WRITES;
 	return 0;
 }
 
@@ -1083,7 +1083,7 @@ static const struct scsi_host_template iscsi_sw_tcp_sht = {
 	.eh_device_reset_handler= iscsi_eh_device_reset,
 	.eh_target_reset_handler = iscsi_eh_recover_target,
 	.dma_boundary		= PAGE_SIZE - 1,
-	.slave_configure        = iscsi_sw_tcp_slave_configure,
+	.device_configure	= iscsi_sw_tcp_device_configure,
 	.proc_name		= "iscsi_tcp",
 	.this_id		= -1,
 	.track_queue_depth	= 1,

include/linux/blkdev.h

@@ -298,13 +298,17 @@ enum {
 
 	/* do disk/partitions IO accounting */
 	BLK_FEAT_IO_STAT			= (1u << 4),
+
+	/* don't modify data until writeback is done */
+	BLK_FEAT_STABLE_WRITES			= (1u << 5),
 };
 
 /*
  * Flags automatically inherited when stacking limits.
  */
 #define BLK_FEAT_INHERIT_MASK \
-	(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA | BLK_FEAT_ROTATIONAL)
+	(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA | BLK_FEAT_ROTATIONAL | \
+	 BLK_FEAT_STABLE_WRITES)
 
 /* internal flags in queue_limits.flags */
 enum {
@@ -565,7 +569,6 @@ struct request_queue {
 #define QUEUE_FLAG_SYNCHRONOUS	11	/* always completes in submit context */
 #define QUEUE_FLAG_SAME_FORCE	12	/* force complete on same CPU */
 #define QUEUE_FLAG_INIT_DONE	14	/* queue is initialized */
-#define QUEUE_FLAG_STABLE_WRITES 15	/* don't modify blks until WB is done */
 #define QUEUE_FLAG_POLL		16	/* IO polling enabled if set */
 #define QUEUE_FLAG_DAX		19	/* device supports DAX */
 #define QUEUE_FLAG_STATS	20	/* track IO start and completion times */
@@ -1323,7 +1326,7 @@ static inline bool bdev_stable_writes(struct block_device *bdev)
 	if (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY) &&
 	    q->limits.integrity.csum_type != BLK_INTEGRITY_CSUM_NONE)
 		return true;
-	return test_bit(QUEUE_FLAG_STABLE_WRITES, &q->queue_flags);
+	return q->limits.features & BLK_FEAT_STABLE_WRITES;
 }
 
 static inline bool blk_queue_write_cache(struct request_queue *q)