[PATCH 0/8] Block layer patches for kernel v5.5

[PATCH 0/8] Block layer patches for kernel v5.5

[Bart Van Assche]

Hi Jens,

This patch series includes the patches I prepared for kernel v5.5. Please
consider these patches for inclusion in the upstream kernel.

Thanks,

Bart.

Bart Van Assche (8):
  block: Fix three kernel-doc warnings
  block: Fix writeback throttling W=1 compiler warnings
  block: Remove request_queue.nr_queues
  block: Remove "dying" checks from sysfs callbacks
  block: Reduce sysfs_lock locking inside blk_cleanup_queue()
  block: Document all members of blk_mq_tag_set and bkl_mq_queue_map
  null_blk: Improve nullb_device_##NAME##_store() readability
  null_blk: Enable modifying 'submit_queues' after an instance has been
    configured

 block/blk-core.c              |  4 +-
 block/blk-mq-sysfs.c          | 16 ++-----
 block/blk-mq.c                |  6 +--
 block/blk-sysfs.c             |  8 ----
 block/t10-pi.c                |  8 +---
 drivers/block/null_blk_main.c | 78 +++++++++++++++++++++++------------
 include/linux/blk-mq.h        | 54 +++++++++++++++++++-----
 include/linux/blkdev.h        |  1 -
 include/trace/events/wbt.h    | 12 ++++--
 9 files changed, 114 insertions(+), 73 deletions(-)

[PATCH 1/8] block: Fix three kernel-doc warnings

[Bart Van Assche]

Fix the following kernel-doc warnings:

block/t10-pi.c:242: warning: Function parameter or member 'rq' not described in 't10_pi_type3_prepare'
block/t10-pi.c:249: warning: Function parameter or member 'rq' not described in 't10_pi_type3_complete'
block/t10-pi.c:249: warning: Function parameter or member 'nr_bytes' not described in 't10_pi_type3_complete'

Cc: Max Gurtovoy <maxg@mellanox.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Fixes: 54d4e6ab91eb ("block: centralize PI remapping logic to the block layer")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/t10-pi.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/block/t10-pi.c b/block/t10-pi.c
index 9803c7e0376e..f4907d941f03 100644
--- a/block/t10-pi.c
+++ b/block/t10-pi.c
@@ -235,16 +235,12 @@ static blk_status_t t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
 	return t10_pi_verify(iter, t10_pi_ip_fn, T10_PI_TYPE3_PROTECTION);
 }
 
-/**
- * Type 3 does not have a reference tag so no remapping is required.
- */
+/* Type 3 does not have a reference tag so no remapping is required. */
 static void t10_pi_type3_prepare(struct request *rq)
 {
 }
 
-/**
- * Type 3 does not have a reference tag so no remapping is required.
- */
+/* Type 3 does not have a reference tag so no remapping is required. */
 static void t10_pi_type3_complete(struct request *rq, unsigned int nr_bytes)
 {
 }
-- 
2.23.0.444.g18eeb5a265-goog

[PATCH 2/8] block: Fix writeback throttling W=1 compiler warnings

[Bart Van Assche]

Fix the following compiler warnings:

In file included from ./include/linux/bitmap.h:9,
                 from ./include/linux/cpumask.h:12,
                 from ./arch/x86/include/asm/cpumask.h:5,
                 from ./arch/x86/include/asm/msr.h:11,
                 from ./arch/x86/include/asm/processor.h:21,
                 from ./arch/x86/include/asm/cpufeature.h:5,
                 from ./arch/x86/include/asm/thread_info.h:53,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from ./include/linux/mmzone.h:8,
                 from ./include/linux/gfp.h:6,
                 from ./include/linux/mm.h:10,
                 from ./include/linux/bvec.h:13,
                 from ./include/linux/blk_types.h:10,
                 from block/blk-wbt.c:23:
In function 'strncpy',
    inlined from 'perf_trace_wbt_stat' at ./include/trace/events/wbt.h:15:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'perf_trace_wbt_lat' at ./include/trace/events/wbt.h:58:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'perf_trace_wbt_step' at ./include/trace/events/wbt.h:87:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'perf_trace_wbt_timer' at ./include/trace/events/wbt.h:126:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_stat' at ./include/trace/events/wbt.h:15:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_lat' at ./include/trace/events/wbt.h:58:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_timer' at ./include/trace/events/wbt.h:126:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_step' at ./include/trace/events/wbt.h:87:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Fixes: e34cbd307477 ("blk-wbt: add general throttling mechanism"; v4.10).
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/trace/events/wbt.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/trace/events/wbt.h b/include/trace/events/wbt.h
index b048694070e2..37342a13c9cb 100644
--- a/include/trace/events/wbt.h
+++ b/include/trace/events/wbt.h
@@ -33,7 +33,8 @@ TRACE_EVENT(wbt_stat,
 	),
 
 	TP_fast_assign(
-		strncpy(__entry->name, dev_name(bdi->dev), 32);
+		strlcpy(__entry->name, dev_name(bdi->dev),
+			ARRAY_SIZE(__entry->name));
 		__entry->rmean		= stat[0].mean;
 		__entry->rmin		= stat[0].min;
 		__entry->rmax		= stat[0].max;
@@ -67,7 +68,8 @@ TRACE_EVENT(wbt_lat,
 	),
 
 	TP_fast_assign(
-		strncpy(__entry->name, dev_name(bdi->dev), 32);
+		strlcpy(__entry->name, dev_name(bdi->dev),
+			ARRAY_SIZE(__entry->name));
 		__entry->lat = div_u64(lat, 1000);
 	),
 
@@ -103,7 +105,8 @@ TRACE_EVENT(wbt_step,
 	),
 
 	TP_fast_assign(
-		strncpy(__entry->name, dev_name(bdi->dev), 32);
+		strlcpy(__entry->name, dev_name(bdi->dev),
+			ARRAY_SIZE(__entry->name));
 		__entry->msg	= msg;
 		__entry->step	= step;
 		__entry->window	= div_u64(window, 1000);
@@ -138,7 +141,8 @@ TRACE_EVENT(wbt_timer,
 	),
 
 	TP_fast_assign(
-		strncpy(__entry->name, dev_name(bdi->dev), 32);
+		strlcpy(__entry->name, dev_name(bdi->dev),
+			ARRAY_SIZE(__entry->name));
 		__entry->status		= status;
 		__entry->step		= step;
 		__entry->inflight	= inflight;
-- 
2.23.0.444.g18eeb5a265-goog

[PATCH 3/8] block: Remove request_queue.nr_queues

[Bart Van Assche]

Commit 897bb0c7f1ea ("blk-mq: Use proper cpumask iterator"; v4.6)
removed the last use of request_queue.nr_queues from outside
blk_mq_init_allocate_queue(). Remove this member variable to make
struct request_queue smaller. This patch does not change any
functionality.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-mq.c         | 6 +++---
 include/linux/blkdev.h | 1 -
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 29275f5a996f..25b8a9b44a31 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2867,9 +2867,9 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	/* init q->mq_kobj and sw queues' kobjects */
 	blk_mq_sysfs_init(q);
 
-	q->nr_queues = nr_hw_queues(set);
-	q->queue_hw_ctx = kcalloc_node(q->nr_queues, sizeof(*(q->queue_hw_ctx)),
-						GFP_KERNEL, set->numa_node);
+	q->queue_hw_ctx = kcalloc_node(nr_hw_queues(set),
+				       sizeof(*(q->queue_hw_ctx)), GFP_KERNEL,
+				       set->numa_node);
 	if (!q->queue_hw_ctx)
 		goto err_sys_init;
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6032bb740cf4..fe32e07c5e3c 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -411,7 +411,6 @@ struct request_queue {
 
 	/* sw queues */
 	struct blk_mq_ctx __percpu	*queue_ctx;
-	unsigned int		nr_queues;
 
 	unsigned int		queue_depth;
 
-- 
2.23.0.444.g18eeb5a265-goog

[PATCH 4/8] block: Remove "dying" checks from sysfs callbacks

[Bart Van Assche]

Block drivers must call del_gendisk() before blk_cleanup_queue().
del_gendisk() calls kobject_del() and kobject_del() waits until any
ongoing sysfs callback functions have finished. In other words, the
sysfs callback functions won't be called for a queue in the dying
state. Hence remove the "dying" checks from the sysfs callback
functions.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-core.c     |  2 ++
 block/blk-mq-sysfs.c | 16 ++++------------
 block/blk-sysfs.c    |  8 --------
 3 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index d5e668ec751b..8b51d9ec8ae3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -336,6 +336,8 @@ EXPORT_SYMBOL_GPL(blk_set_queue_dying);
  */
 void blk_cleanup_queue(struct request_queue *q)
 {
+	WARN_ON_ONCE(blk_queue_registered(q));
+
 	/* mark @q DYING, no new request or merges will be allowed afterwards */
 	mutex_lock(&q->sysfs_lock);
 	blk_set_queue_dying(q);
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index a0d3ce30fa08..81a273b43329 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -74,10 +74,8 @@ static ssize_t blk_mq_sysfs_show(struct kobject *kobj, struct attribute *attr,
 	if (!entry->show)
 		return -EIO;
 
-	res = -ENOENT;
 	mutex_lock(&q->sysfs_lock);
-	if (!blk_queue_dying(q))
-		res = entry->show(ctx, page);
+	res = entry->show(ctx, page);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
 }
@@ -97,10 +95,8 @@ static ssize_t blk_mq_sysfs_store(struct kobject *kobj, struct attribute *attr,
 	if (!entry->store)
 		return -EIO;
 
-	res = -ENOENT;
 	mutex_lock(&q->sysfs_lock);
-	if (!blk_queue_dying(q))
-		res = entry->store(ctx, page, length);
+	res = entry->store(ctx, page, length);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
 }
@@ -120,10 +116,8 @@ static ssize_t blk_mq_hw_sysfs_show(struct kobject *kobj,
 	if (!entry->show)
 		return -EIO;
 
-	res = -ENOENT;
 	mutex_lock(&q->sysfs_lock);
-	if (!blk_queue_dying(q))
-		res = entry->show(hctx, page);
+	res = entry->show(hctx, page);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
 }
@@ -144,10 +138,8 @@ static ssize_t blk_mq_hw_sysfs_store(struct kobject *kobj,
 	if (!entry->store)
 		return -EIO;
 
-	res = -ENOENT;
 	mutex_lock(&q->sysfs_lock);
-	if (!blk_queue_dying(q))
-		res = entry->store(hctx, page, length);
+	res = entry->store(hctx, page, length);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
 }
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index b82736c781c5..80df16be9f52 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -802,10 +802,6 @@ queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 	if (!entry->show)
 		return -EIO;
 	mutex_lock(&q->sysfs_lock);
-	if (blk_queue_dying(q)) {
-		mutex_unlock(&q->sysfs_lock);
-		return -ENOENT;
-	}
 	res = entry->show(q, page);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
@@ -824,10 +820,6 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr,
 
 	q = container_of(kobj, struct request_queue, kobj);
 	mutex_lock(&q->sysfs_lock);
-	if (blk_queue_dying(q)) {
-		mutex_unlock(&q->sysfs_lock);
-		return -ENOENT;
-	}
 	res = entry->store(q, page, length);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
-- 
2.23.0.444.g18eeb5a265-goog

[PATCH 5/8] block: Reduce sysfs_lock locking inside blk_cleanup_queue()

[Bart Van Assche]

Since blk_cleanup_queue() is called after blk_unregister_queue() and
since that last function removes all sysfs attributes, serializing
any code in blk_cleanup_queue() against sysfs callback methods nor against
I/O scheduler changes is necessary. Hence remove the syfs_lock locking
calls from the start of blk_cleanup_queue().

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 8b51d9ec8ae3..ae506ac2dd48 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -339,13 +339,11 @@ void blk_cleanup_queue(struct request_queue *q)
 	WARN_ON_ONCE(blk_queue_registered(q));
 
 	/* mark @q DYING, no new request or merges will be allowed afterwards */
-	mutex_lock(&q->sysfs_lock);
 	blk_set_queue_dying(q);
 
 	blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q);
 	blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
 	blk_queue_flag_set(QUEUE_FLAG_DYING, q);
-	mutex_unlock(&q->sysfs_lock);
 
 	/*
 	 * Drain all requests queued before DYING marking. Set DEAD flag to
-- 
2.23.0.444.g18eeb5a265-goog

[PATCH 6/8] block: Document all members of blk_mq_tag_set and bkl_mq_queue_map

[Bart Van Assche]

The meaning of several member variables of these two data structures is
nontrivial. Hence document all member variables using the kernel-doc
syntax.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/linux/blk-mq.h | 54 +++++++++++++++++++++++++++++++++---------
 1 file changed, 43 insertions(+), 11 deletions(-)

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 0bf056de5cc3..a96b5cc957ab 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -76,6 +76,16 @@ struct blk_mq_hw_ctx {
 	struct srcu_struct	srcu[0];
 };
 
+/**
+ * struct blk_mq_queue_map - ctx -> hctx mapping
+ * @mq_map:       CPU ID to hardware queue index map. This is an array
+ *	with nr_cpu_ids elements. Each element has a value in the range
+ *	[@queue_offset, @queue_offset + @nr_queues).
+ * @nr_queues:    Number of hardware queues to map CPU IDs onto.
+ * @queue_offset: First hardware queue to map onto. Used by the PCIe NVMe
+ *	driver to map each hardware queue type (enum hctx_type) onto a distinct
+ *	set of hardware queues.
+ */
 struct blk_mq_queue_map {
 	unsigned int *mq_map;
 	unsigned int nr_queues;
@@ -90,23 +100,45 @@ enum hctx_type {
 	HCTX_MAX_TYPES,
 };
 
+/**
+ * struct blk_mq_tag_set - tag set that can be shared between request queues
+ * @map:	   One or more ctx -> hctx mappings. One map exists for each
+ *		   hardware queue type (enum hctx_type) that the driver wishes
+ *		   to support. There are no restrictions on maps being of the
+ *		   same size, and it's perfectly legal to share maps between
+ *		   types.
+ * @nr_maps:	   Number of elements in the @map array. A number in the range
+ *		   [1, HCTX_MAX_TYPES].
+ * @ops:	   Pointers to functions that implement block driver behavior.
+ * @nr_hw_queues:  Number of hardware queues supported by the block driver that
+ *		   owns this data structure.
+ * @queue_depth:   Number of tags per hardware queue, reserved tags included.
+ * @reserved_tags: Number of tags to set aside for BLK_MQ_REQ_RESERVED tag
+ *		   allocations.
+ * @cmd_size:	   Number of additional bytes to allocate per request. The block
+ *		   driver owns these additional bytes.
+ * @numa_node:	   NUMA node the storage adapter has been connected to.
+ * @timeout:	   Request processing timeout in jiffies.
+ * @flags:	   Zero or more BLK_MQ_F_* flags.
+ * @driver_data:   Pointer to data owned by the block driver that created this
+ *		   tag set.
+ * @tags:	   Tag sets. One tag set per hardware queue. Has @nr_hw_queues
+ *		   elements.
+ * @tag_list_lock: Serializes tag_list accesses.
+ * @tag_list:	   List of the request queues that use this tag set. See also
+ *		   request_queue.tag_set_list.
+ */
 struct blk_mq_tag_set {
-	/*
-	 * map[] holds ctx -> hctx mappings, one map exists for each type
-	 * that the driver wishes to support. There are no restrictions
-	 * on maps being of the same size, and it's perfectly legal to
-	 * share maps between types.
-	 */
 	struct blk_mq_queue_map	map[HCTX_MAX_TYPES];
-	unsigned int		nr_maps;	/* nr entries in map[] */
+	unsigned int		nr_maps;
 	const struct blk_mq_ops	*ops;
-	unsigned int		nr_hw_queues;	/* nr hw queues across maps */
-	unsigned int		queue_depth;	/* max hw supported */
+	unsigned int		nr_hw_queues;
+	unsigned int		queue_depth;
 	unsigned int		reserved_tags;
-	unsigned int		cmd_size;	/* per-request extra data */
+	unsigned int		cmd_size;
 	int			numa_node;
 	unsigned int		timeout;
-	unsigned int		flags;		/* BLK_MQ_F_* */
+	unsigned int		flags;
 	void			*driver_data;
 
 	struct blk_mq_tags	**tags;
-- 
2.23.0.444.g18eeb5a265-goog

[PATCH 7/8] null_blk: Improve nullb_device_##NAME##_store() readability

[Bart Van Assche]

Introduce a local variable to make the code easier to read. This patch
does not change any functionality but makes the next patch in this
series easier to read.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/block/null_blk_main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 0e7da5015ccd..f5747cfd806f 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -274,10 +274,11 @@ static ssize_t									\
 nullb_device_##NAME##_store(struct config_item *item, const char *page,		\
 			    size_t count)					\
 {										\
-	if (test_bit(NULLB_DEV_FL_CONFIGURED, &to_nullb_device(item)->flags))	\
+	struct nullb_device *dev = to_nullb_device(item);			\
+										\
+	if (test_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags))			\
 		return -EBUSY;							\
-	return nullb_device_##TYPE##_attr_store(				\
-			&to_nullb_device(item)->NAME, page, count);		\
+	return nullb_device_##TYPE##_attr_store(&dev->NAME, page, count);	\
 }										\
 CONFIGFS_ATTR(nullb_device_, NAME);
 
-- 
2.23.0.444.g18eeb5a265-goog

[PATCH 8/8] null_blk: Enable modifying 'submit_queues' after an instance has been configured

[Bart Van Assche]

This patch makes it possible to test blk_mq_update_nr_hw_queues() from
inside a VM.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/block/null_blk_main.c | 75 +++++++++++++++++++++++------------
 1 file changed, 50 insertions(+), 25 deletions(-)

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index f5747cfd806f..f5e0dffb4624 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -227,7 +227,7 @@ static ssize_t nullb_device_uint_attr_store(unsigned int *val,
 	int result;
 
 	result = kstrtouint(page, 0, &tmp);
-	if (result)
+	if (result < 0)
 		return result;
 
 	*val = tmp;
@@ -241,7 +241,7 @@ static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
 	unsigned long tmp;
 
 	result = kstrtoul(page, 0, &tmp);
-	if (result)
+	if (result < 0)
 		return result;
 
 	*val = tmp;
@@ -255,7 +255,7 @@ static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
 	int result;
 
 	result = kstrtobool(page,  &tmp);
-	if (result)
+	if (result < 0)
 		return result;
 
 	*val = tmp;
@@ -263,7 +263,7 @@ static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
 }
 
 /* The following macro should only be used with TYPE = {uint, ulong, bool}. */
-#define NULLB_DEVICE_ATTR(NAME, TYPE)						\
+#define NULLB_DEVICE_ATTR(NAME, TYPE, APPLY)					\
 static ssize_t									\
 nullb_device_##NAME##_show(struct config_item *item, char *page)		\
 {										\
@@ -274,32 +274,57 @@ static ssize_t									\
 nullb_device_##NAME##_store(struct config_item *item, const char *page,		\
 			    size_t count)					\
 {										\
+	int (*apply_fn)(struct nullb_device *dev, TYPE new_value) = APPLY;	\
 	struct nullb_device *dev = to_nullb_device(item);			\
+	TYPE new_value;								\
+	int ret;								\
 										\
-	if (test_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags))			\
-		return -EBUSY;							\
-	return nullb_device_##TYPE##_attr_store(&dev->NAME, page, count);	\
+	ret = nullb_device_##TYPE##_attr_store(&new_value, page, count);	\
+	if (ret < 0)								\
+		return ret;							\
+	if (apply_fn)								\
+		ret = apply_fn(dev, new_value);					\
+	else if (test_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags)) 		\
+		ret = -EBUSY;							\
+	if (ret < 0)								\
+		return ret;							\
+	dev->NAME = new_value;							\
+	return count;								\
 }										\
 CONFIGFS_ATTR(nullb_device_, NAME);
 
-NULLB_DEVICE_ATTR(size, ulong);
-NULLB_DEVICE_ATTR(completion_nsec, ulong);
-NULLB_DEVICE_ATTR(submit_queues, uint);
-NULLB_DEVICE_ATTR(home_node, uint);
-NULLB_DEVICE_ATTR(queue_mode, uint);
-NULLB_DEVICE_ATTR(blocksize, uint);
-NULLB_DEVICE_ATTR(irqmode, uint);
-NULLB_DEVICE_ATTR(hw_queue_depth, uint);
-NULLB_DEVICE_ATTR(index, uint);
-NULLB_DEVICE_ATTR(blocking, bool);
-NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
-NULLB_DEVICE_ATTR(memory_backed, bool);
-NULLB_DEVICE_ATTR(discard, bool);
-NULLB_DEVICE_ATTR(mbps, uint);
-NULLB_DEVICE_ATTR(cache_size, ulong);
-NULLB_DEVICE_ATTR(zoned, bool);
-NULLB_DEVICE_ATTR(zone_size, ulong);
-NULLB_DEVICE_ATTR(zone_nr_conv, uint);
+static int nullb_apply_submit_queues(struct nullb_device *dev,
+				     unsigned int submit_queues)
+{
+	struct nullb *nullb = dev->nullb;
+	struct blk_mq_tag_set *set;
+
+	if (!nullb)
+		return 0;
+
+	set = nullb->tag_set;
+	blk_mq_update_nr_hw_queues(set, submit_queues);
+	return set->nr_hw_queues == submit_queues ? 0 : -ENOMEM;
+}
+
+NULLB_DEVICE_ATTR(size, ulong, NULL);
+NULLB_DEVICE_ATTR(completion_nsec, ulong, NULL);
+NULLB_DEVICE_ATTR(submit_queues, uint, nullb_apply_submit_queues);
+NULLB_DEVICE_ATTR(home_node, uint, NULL);
+NULLB_DEVICE_ATTR(queue_mode, uint, NULL);
+NULLB_DEVICE_ATTR(blocksize, uint, NULL);
+NULLB_DEVICE_ATTR(irqmode, uint, NULL);
+NULLB_DEVICE_ATTR(hw_queue_depth, uint, NULL);
+NULLB_DEVICE_ATTR(index, uint, NULL);
+NULLB_DEVICE_ATTR(blocking, bool, NULL);
+NULLB_DEVICE_ATTR(use_per_node_hctx, bool, NULL);
+NULLB_DEVICE_ATTR(memory_backed, bool, NULL);
+NULLB_DEVICE_ATTR(discard, bool, NULL);
+NULLB_DEVICE_ATTR(mbps, uint, NULL);
+NULLB_DEVICE_ATTR(cache_size, ulong, NULL);
+NULLB_DEVICE_ATTR(zoned, bool, NULL);
+NULLB_DEVICE_ATTR(zone_size, ulong, NULL);
+NULLB_DEVICE_ATTR(zone_nr_conv, uint, NULL);
 
 static ssize_t nullb_device_power_show(struct config_item *item, char *page)
 {
-- 
2.23.0.444.g18eeb5a265-goog

Re: [PATCH 0/8] Block layer patches for kernel v5.5

[Jens Axboe]

On 9/30/19 5:00 PM, Bart Van Assche wrote:
> Hi Jens,
> 
> This patch series includes the patches I prepared for kernel v5.5. Please
> consider these patches for inclusion in the upstream kernel.

Thanks Bart, applied.

-- 
Jens Axboe