[PATCH v2 00/12] blk-mq-sched: scheduler support and cleanups

[PATCH v2 00/12] blk-mq-sched: scheduler support and cleanups

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

This series makes several enhancements to blk-mq-debugfs. v2 adds
patches 3, 4, and 5. It also exports a couple of symbols needed in
patches 11 and 12.

- Patch 1 is a subjective change.
- Patch 2 is a cleanup.
- Patches 3 and 4 are minor tweaks to the queue "state" attribute.
- Patch 5 renames the hardware queue directories.
- Patch 6 cleans up a bunch of seq_file boilerplate.
- Patch 7 is Bart's patch from a couple of weeks ago, necessitated by
  patch 9.
- Patch 8 is preparation cleanup for patches 9-12.
- Patch 9 reworks the lifetimes of the debugfs attributes to be tied to
  the structure lifetimes themselves rather being duct taped on to
  sysfs. This is what I should have done in the first place, and would
  have also been a way to fix the same thing we fixed in e869b5462f83
  ("blk-mq: Unregister debugfs attributes earlier"), but I didn't think
  of doing it this way until I started adding scheduler support.
- Patch 10 allows schedulers to register debugfs attributes, implemented
  in patches 11 and 12 for kyber and mq-deadline, respectively.

Bart Van Assche (1):
  blk-mq: Do not invoke queue operations on a dead queue

Omar Sandoval (11):
  blk-mq-debugfs: separate flags with |
  blk-mq-debugfs: clean up flag definitions
  blk-mq-debugfs: error on long write to queue "state" file
  blk-mq-debugfs: don't open code strstrip()
  blk-mq-debugfs: rename hw queue directories from <n> to hctx<n>
  blk-mq-debugfs: get rid of a bunch of boilerplate
  blk-mq: move debugfs declarations to a separate header file
  blk-mq: untangle debugfs and sysfs
  blk-mq-debugfs: allow schedulers to register debugfs attributes
  kyber: add debugfs attributes
  mq-deadline: add debugfs attributes

 block/blk-core.c         |   8 +-
 block/blk-mq-debugfs.c   | 870 +++++++++++++++++++++--------------------------
 block/blk-mq-debugfs.h   |  79 +++++
 block/blk-mq-sched.c     |  24 +-
 block/blk-mq-sysfs.c     |  10 -
 block/blk-mq.c           |   7 +
 block/blk-mq.h           |  28 --
 block/blk-sysfs.c        |   3 +
 block/kyber-iosched.c    | 130 +++++++
 block/mq-deadline.c      | 123 +++++++
 include/linux/blk-mq.h   |   5 +
 include/linux/blkdev.h   |   2 +-
 include/linux/elevator.h |   7 +
 13 files changed, 764 insertions(+), 532 deletions(-)
 create mode 100644 block/blk-mq-debugfs.h

-- 
2.12.2

[PATCH v2 01/12] blk-mq-debugfs: separate flags with |

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

This reads more naturally than spaces.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index bcd2a7d4a3a5..1ff3d726fb03 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -53,7 +53,7 @@ static int blk_flags_show(struct seq_file *m, const unsigned long flags,
 		if (!(flags & BIT(i)))
 			continue;
 		if (sep)
-			seq_puts(m, " ");
+			seq_puts(m, "|");
 		sep = true;
 		if (i < flag_name_count && flag_name[i])
 			seq_puts(m, flag_name[i]);
-- 
2.12.2

[PATCH v2 02/12] blk-mq-debugfs: clean up flag definitions

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Make sure the spelled out flag names match the definition. This also
adds a missing hctx state, BLK_MQ_S_START_ON_RUN, and a missing
cmd_flag, __REQ_NOUNMAP.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c | 201 ++++++++++++++++++++++++++-----------------------
 1 file changed, 108 insertions(+), 93 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 1ff3d726fb03..f58a116d6cca 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -63,37 +63,39 @@ static int blk_flags_show(struct seq_file *m, const unsigned long flags,
 	return 0;
 }
 
+#define QUEUE_FLAG_NAME(name) [QUEUE_FLAG_##name] = #name
 static const char *const blk_queue_flag_name[] = {
-	[QUEUE_FLAG_QUEUED]	 = "QUEUED",
-	[QUEUE_FLAG_STOPPED]	 = "STOPPED",
-	[QUEUE_FLAG_SYNCFULL]	 = "SYNCFULL",
-	[QUEUE_FLAG_ASYNCFULL]	 = "ASYNCFULL",
-	[QUEUE_FLAG_DYING]	 = "DYING",
-	[QUEUE_FLAG_BYPASS]	 = "BYPASS",
-	[QUEUE_FLAG_BIDI]	 = "BIDI",
-	[QUEUE_FLAG_NOMERGES]	 = "NOMERGES",
-	[QUEUE_FLAG_SAME_COMP]	 = "SAME_COMP",
-	[QUEUE_FLAG_FAIL_IO]	 = "FAIL_IO",
-	[QUEUE_FLAG_STACKABLE]	 = "STACKABLE",
-	[QUEUE_FLAG_NONROT]	 = "NONROT",
-	[QUEUE_FLAG_IO_STAT]	 = "IO_STAT",
-	[QUEUE_FLAG_DISCARD]	 = "DISCARD",
-	[QUEUE_FLAG_NOXMERGES]	 = "NOXMERGES",
-	[QUEUE_FLAG_ADD_RANDOM]	 = "ADD_RANDOM",
-	[QUEUE_FLAG_SECERASE]	 = "SECERASE",
-	[QUEUE_FLAG_SAME_FORCE]	 = "SAME_FORCE",
-	[QUEUE_FLAG_DEAD]	 = "DEAD",
-	[QUEUE_FLAG_INIT_DONE]	 = "INIT_DONE",
-	[QUEUE_FLAG_NO_SG_MERGE] = "NO_SG_MERGE",
-	[QUEUE_FLAG_POLL]	 = "POLL",
-	[QUEUE_FLAG_WC]		 = "WC",
-	[QUEUE_FLAG_FUA]	 = "FUA",
-	[QUEUE_FLAG_FLUSH_NQ]	 = "FLUSH_NQ",
-	[QUEUE_FLAG_DAX]	 = "DAX",
-	[QUEUE_FLAG_STATS]	 = "STATS",
-	[QUEUE_FLAG_POLL_STATS]	 = "POLL_STATS",
-	[QUEUE_FLAG_REGISTERED]	 = "REGISTERED",
-};
+	QUEUE_FLAG_NAME(QUEUED),
+	QUEUE_FLAG_NAME(STOPPED),
+	QUEUE_FLAG_NAME(SYNCFULL),
+	QUEUE_FLAG_NAME(ASYNCFULL),
+	QUEUE_FLAG_NAME(DYING),
+	QUEUE_FLAG_NAME(BYPASS),
+	QUEUE_FLAG_NAME(BIDI),
+	QUEUE_FLAG_NAME(NOMERGES),
+	QUEUE_FLAG_NAME(SAME_COMP),
+	QUEUE_FLAG_NAME(FAIL_IO),
+	QUEUE_FLAG_NAME(STACKABLE),
+	QUEUE_FLAG_NAME(NONROT),
+	QUEUE_FLAG_NAME(IO_STAT),
+	QUEUE_FLAG_NAME(DISCARD),
+	QUEUE_FLAG_NAME(NOXMERGES),
+	QUEUE_FLAG_NAME(ADD_RANDOM),
+	QUEUE_FLAG_NAME(SECERASE),
+	QUEUE_FLAG_NAME(SAME_FORCE),
+	QUEUE_FLAG_NAME(DEAD),
+	QUEUE_FLAG_NAME(INIT_DONE),
+	QUEUE_FLAG_NAME(NO_SG_MERGE),
+	QUEUE_FLAG_NAME(POLL),
+	QUEUE_FLAG_NAME(WC),
+	QUEUE_FLAG_NAME(FUA),
+	QUEUE_FLAG_NAME(FLUSH_NQ),
+	QUEUE_FLAG_NAME(DAX),
+	QUEUE_FLAG_NAME(STATS),
+	QUEUE_FLAG_NAME(POLL_STATS),
+	QUEUE_FLAG_NAME(REGISTERED),
+};
+#undef QUEUE_FLAG_NAME
 
 static int blk_queue_flags_show(struct seq_file *m, void *v)
 {
@@ -180,13 +182,16 @@ static const struct file_operations queue_poll_stat_fops = {
 	.release	= single_release,
 };
 
+#define HCTX_STATE_NAME(name) [BLK_MQ_S_##name] = #name
 static const char *const hctx_state_name[] = {
-	[BLK_MQ_S_STOPPED]	 = "STOPPED",
-	[BLK_MQ_S_TAG_ACTIVE]	 = "TAG_ACTIVE",
-	[BLK_MQ_S_SCHED_RESTART] = "SCHED_RESTART",
-	[BLK_MQ_S_TAG_WAITING]	 = "TAG_WAITING",
-
+	HCTX_STATE_NAME(STOPPED),
+	HCTX_STATE_NAME(TAG_ACTIVE),
+	HCTX_STATE_NAME(SCHED_RESTART),
+	HCTX_STATE_NAME(TAG_WAITING),
+	HCTX_STATE_NAME(START_ON_RUN),
 };
+#undef HCTX_STATE_NAME
+
 static int hctx_state_show(struct seq_file *m, void *v)
 {
 	struct blk_mq_hw_ctx *hctx = m->private;
@@ -209,18 +214,22 @@ static const struct file_operations hctx_state_fops = {
 	.release	= single_release,
 };
 
+#define BLK_TAG_ALLOC_NAME(name) [BLK_TAG_ALLOC_##name] = #name
 static const char *const alloc_policy_name[] = {
-	[BLK_TAG_ALLOC_FIFO]	= "fifo",
-	[BLK_TAG_ALLOC_RR]	= "rr",
+	BLK_TAG_ALLOC_NAME(FIFO),
+	BLK_TAG_ALLOC_NAME(RR),
 };
+#undef BLK_TAG_ALLOC_NAME
 
+#define HCTX_FLAG_NAME(name) [ilog2(BLK_MQ_F_##name)] = #name
 static const char *const hctx_flag_name[] = {
-	[ilog2(BLK_MQ_F_SHOULD_MERGE)]	= "SHOULD_MERGE",
-	[ilog2(BLK_MQ_F_TAG_SHARED)]	= "TAG_SHARED",
-	[ilog2(BLK_MQ_F_SG_MERGE)]	= "SG_MERGE",
-	[ilog2(BLK_MQ_F_BLOCKING)]	= "BLOCKING",
-	[ilog2(BLK_MQ_F_NO_SCHED)]	= "NO_SCHED",
+	HCTX_FLAG_NAME(SHOULD_MERGE),
+	HCTX_FLAG_NAME(TAG_SHARED),
+	HCTX_FLAG_NAME(SG_MERGE),
+	HCTX_FLAG_NAME(BLOCKING),
+	HCTX_FLAG_NAME(NO_SCHED),
 };
+#undef HCTX_FLAG_NAME
 
 static int hctx_flags_show(struct seq_file *m, void *v)
 {
@@ -253,60 +262,66 @@ static const struct file_operations hctx_flags_fops = {
 	.release	= single_release,
 };
 
+#define REQ_OP_NAME(name) [REQ_OP_##name] = #name
 static const char *const op_name[] = {
-	[REQ_OP_READ]		= "READ",
-	[REQ_OP_WRITE]		= "WRITE",
-	[REQ_OP_FLUSH]		= "FLUSH",
-	[REQ_OP_DISCARD]	= "DISCARD",
-	[REQ_OP_ZONE_REPORT]	= "ZONE_REPORT",
-	[REQ_OP_SECURE_ERASE]	= "SECURE_ERASE",
-	[REQ_OP_ZONE_RESET]	= "ZONE_RESET",
-	[REQ_OP_WRITE_SAME]	= "WRITE_SAME",
-	[REQ_OP_WRITE_ZEROES]	= "WRITE_ZEROES",
-	[REQ_OP_SCSI_IN]	= "SCSI_IN",
-	[REQ_OP_SCSI_OUT]	= "SCSI_OUT",
-	[REQ_OP_DRV_IN]		= "DRV_IN",
-	[REQ_OP_DRV_OUT]	= "DRV_OUT",
-};
-
+	REQ_OP_NAME(READ),
+	REQ_OP_NAME(WRITE),
+	REQ_OP_NAME(FLUSH),
+	REQ_OP_NAME(DISCARD),
+	REQ_OP_NAME(ZONE_REPORT),
+	REQ_OP_NAME(SECURE_ERASE),
+	REQ_OP_NAME(ZONE_RESET),
+	REQ_OP_NAME(WRITE_SAME),
+	REQ_OP_NAME(WRITE_ZEROES),
+	REQ_OP_NAME(SCSI_IN),
+	REQ_OP_NAME(SCSI_OUT),
+	REQ_OP_NAME(DRV_IN),
+	REQ_OP_NAME(DRV_OUT),
+};
+#undef REQ_OP_NAME
+
+#define CMD_FLAG_NAME(name) [__REQ_##name] = #name
 static const char *const cmd_flag_name[] = {
-	[__REQ_FAILFAST_DEV]		= "FAILFAST_DEV",
-	[__REQ_FAILFAST_TRANSPORT]	= "FAILFAST_TRANSPORT",
-	[__REQ_FAILFAST_DRIVER]		= "FAILFAST_DRIVER",
-	[__REQ_SYNC]			= "SYNC",
-	[__REQ_META]			= "META",
-	[__REQ_PRIO]			= "PRIO",
-	[__REQ_NOMERGE]			= "NOMERGE",
-	[__REQ_IDLE]			= "IDLE",
-	[__REQ_INTEGRITY]		= "INTEGRITY",
-	[__REQ_FUA]			= "FUA",
-	[__REQ_PREFLUSH]		= "PREFLUSH",
-	[__REQ_RAHEAD]			= "RAHEAD",
-	[__REQ_BACKGROUND]		= "BACKGROUND",
-	[__REQ_NR_BITS]			= "NR_BITS",
-};
-
+	CMD_FLAG_NAME(FAILFAST_DEV),
+	CMD_FLAG_NAME(FAILFAST_TRANSPORT),
+	CMD_FLAG_NAME(FAILFAST_DRIVER),
+	CMD_FLAG_NAME(SYNC),
+	CMD_FLAG_NAME(META),
+	CMD_FLAG_NAME(PRIO),
+	CMD_FLAG_NAME(NOMERGE),
+	CMD_FLAG_NAME(IDLE),
+	CMD_FLAG_NAME(INTEGRITY),
+	CMD_FLAG_NAME(FUA),
+	CMD_FLAG_NAME(PREFLUSH),
+	CMD_FLAG_NAME(RAHEAD),
+	CMD_FLAG_NAME(BACKGROUND),
+	CMD_FLAG_NAME(NOUNMAP),
+};
+#undef CMD_FLAG_NAME
+
+#define RQF_NAME(name) [ilog2((__force u32)RQF_##name)] = #name
 static const char *const rqf_name[] = {
-	[ilog2((__force u32)RQF_SORTED)]		= "SORTED",
-	[ilog2((__force u32)RQF_STARTED)]		= "STARTED",
-	[ilog2((__force u32)RQF_QUEUED)]		= "QUEUED",
-	[ilog2((__force u32)RQF_SOFTBARRIER)]		= "SOFTBARRIER",
-	[ilog2((__force u32)RQF_FLUSH_SEQ)]		= "FLUSH_SEQ",
-	[ilog2((__force u32)RQF_MIXED_MERGE)]		= "MIXED_MERGE",
-	[ilog2((__force u32)RQF_MQ_INFLIGHT)]		= "MQ_INFLIGHT",
-	[ilog2((__force u32)RQF_DONTPREP)]		= "DONTPREP",
-	[ilog2((__force u32)RQF_PREEMPT)]		= "PREEMPT",
-	[ilog2((__force u32)RQF_COPY_USER)]		= "COPY_USER",
-	[ilog2((__force u32)RQF_FAILED)]		= "FAILED",
-	[ilog2((__force u32)RQF_QUIET)]			= "QUIET",
-	[ilog2((__force u32)RQF_ELVPRIV)]		= "ELVPRIV",
-	[ilog2((__force u32)RQF_IO_STAT)]		= "IO_STAT",
-	[ilog2((__force u32)RQF_ALLOCED)]		= "ALLOCED",
-	[ilog2((__force u32)RQF_PM)]			= "PM",
-	[ilog2((__force u32)RQF_HASHED)]		= "HASHED",
-	[ilog2((__force u32)RQF_STATS)]			= "STATS",
-	[ilog2((__force u32)RQF_SPECIAL_PAYLOAD)]	= "SPECIAL_PAYLOAD",
-};
+	RQF_NAME(SORTED),
+	RQF_NAME(STARTED),
+	RQF_NAME(QUEUED),
+	RQF_NAME(SOFTBARRIER),
+	RQF_NAME(FLUSH_SEQ),
+	RQF_NAME(MIXED_MERGE),
+	RQF_NAME(MQ_INFLIGHT),
+	RQF_NAME(DONTPREP),
+	RQF_NAME(PREEMPT),
+	RQF_NAME(COPY_USER),
+	RQF_NAME(FAILED),
+	RQF_NAME(QUIET),
+	RQF_NAME(ELVPRIV),
+	RQF_NAME(IO_STAT),
+	RQF_NAME(ALLOCED),
+	RQF_NAME(PM),
+	RQF_NAME(HASHED),
+	RQF_NAME(STATS),
+	RQF_NAME(SPECIAL_PAYLOAD),
+};
+#undef RQF_NAME
 
 static int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
 {
-- 
2.12.2

[PATCH v2 03/12] blk-mq-debugfs: error on long write to queue "state" file

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

blk_queue_flags_store() currently truncates and returns a short write if
the operation being written is too long. This can give us weird results,
like here:

$ echo "run            bar"
echo: write error: invalid argument
$ dmesg
[ 1103.075435] blk_queue_flags_store: unsupported operation bar. Use either 'run' or 'start'

Instead, return an error if the user does this. While we're here, make
the argument names consistent with everywhere else in this file.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index f58a116d6cca..2a19237455d4 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -107,14 +107,18 @@ static int blk_queue_flags_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static ssize_t blk_queue_flags_store(struct file *file, const char __user *ubuf,
-				     size_t len, loff_t *offp)
+static ssize_t blk_queue_flags_store(struct file *file, const char __user *buf,
+				     size_t count, loff_t *ppos)
 {
 	struct request_queue *q = file_inode(file)->i_private;
 	char op[16] = { }, *s;
 
-	len = min(len, sizeof(op) - 1);
-	if (copy_from_user(op, ubuf, len))
+	if (count >= sizeof(op)) {
+		pr_err("%s: operation too long\n", __func__);
+		goto inval;
+	}
+
+	if (copy_from_user(op, buf, count))
 		return -EFAULT;
 	s = op;
 	strsep(&s, " \t\n"); /* strip trailing whitespace */
@@ -123,11 +127,12 @@ static ssize_t blk_queue_flags_store(struct file *file, const char __user *ubuf,
 	} else if (strcmp(op, "start") == 0) {
 		blk_mq_start_stopped_hw_queues(q, true);
 	} else {
-		pr_err("%s: unsupported operation %s. Use either 'run' or 'start'\n",
-		       __func__, op);
+		pr_err("%s: unsupported operation '%s'\n", __func__, op);
+inval:
+		pr_err("%s: use either 'run' or 'start'\n", __func__);
 		return -EINVAL;
 	}
-	return len;
+	return count;
 }
 
 static int blk_queue_flags_open(struct inode *inode, struct file *file)
-- 
2.12.2

[PATCH v2 04/12] blk-mq-debugfs: don't open code strstrip()

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Slightly more readable, plus we also strip leading spaces.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 2a19237455d4..109ae9f3d400 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -111,17 +111,16 @@ static ssize_t blk_queue_flags_store(struct file *file, const char __user *buf,
 				     size_t count, loff_t *ppos)
 {
 	struct request_queue *q = file_inode(file)->i_private;
-	char op[16] = { }, *s;
+	char opbuf[16] = { }, *op;
 
-	if (count >= sizeof(op)) {
+	if (count >= sizeof(opbuf)) {
 		pr_err("%s: operation too long\n", __func__);
 		goto inval;
 	}
 
-	if (copy_from_user(op, buf, count))
+	if (copy_from_user(opbuf, buf, count))
 		return -EFAULT;
-	s = op;
-	strsep(&s, " \t\n"); /* strip trailing whitespace */
+	op = strstrip(opbuf);
 	if (strcmp(op, "run") == 0) {
 		blk_mq_run_hw_queues(q, true);
 	} else if (strcmp(op, "start") == 0) {
-- 
2.12.2

[PATCH v2 05/12] blk-mq-debugfs: rename hw queue directories from <n> to hctx<n>

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

It's not clear what these numbered directories represent unless you
consult the code. We're about to get rid of the intermediate "mq"
directory, so these would be even more confusing without that context.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 109ae9f3d400..2eae3238fb35 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -936,7 +936,7 @@ static int blk_mq_debugfs_register_hctx(struct request_queue *q,
 	char name[20];
 	int i;
 
-	snprintf(name, sizeof(name), "%u", hctx->queue_num);
+	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);
 	hctx_dir = debugfs_create_dir(name, q->mq_debugfs_dir);
 	if (!hctx_dir)
 		return -ENOMEM;
-- 
2.12.2

[PATCH v2 06/12] blk-mq-debugfs: get rid of a bunch of boilerplate

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

A large part of blk-mq-debugfs.c is file_operations and seq_file
boilerplate. This sucks as is but will suck even more when schedulers
can define their own debugfs entries. Factor it all out into a single
blk_mq_debugfs_fops which multiplexes as needed. We store the
request_queue, blk_mq_hw_ctx, or blk_mq_ctx in the parent directory
dentry, which is kind of hacky, but it works.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c | 464 +++++++++++++++----------------------------------
 1 file changed, 136 insertions(+), 328 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 2eae3238fb35..1579af6fcbed 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -26,23 +26,12 @@
 struct blk_mq_debugfs_attr {
 	const char *name;
 	umode_t mode;
-	const struct file_operations *fops;
+	int (*show)(void *, struct seq_file *);
+	ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
+	/* Set either .show or .seq_ops. */
+	const struct seq_operations *seq_ops;
 };
 
-static int blk_mq_debugfs_seq_open(struct inode *inode, struct file *file,
-				   const struct seq_operations *ops)
-{
-	struct seq_file *m;
-	int ret;
-
-	ret = seq_open(file, ops);
-	if (!ret) {
-		m = file->private_data;
-		m->private = inode->i_private;
-	}
-	return ret;
-}
-
 static int blk_flags_show(struct seq_file *m, const unsigned long flags,
 			  const char *const *flag_name, int flag_name_count)
 {
@@ -97,9 +86,9 @@ static const char *const blk_queue_flag_name[] = {
 };
 #undef QUEUE_FLAG_NAME
 
-static int blk_queue_flags_show(struct seq_file *m, void *v)
+static int queue_state_show(void *data, struct seq_file *m)
 {
-	struct request_queue *q = m->private;
+	struct request_queue *q = data;
 
 	blk_flags_show(m, q->queue_flags, blk_queue_flag_name,
 		       ARRAY_SIZE(blk_queue_flag_name));
@@ -107,10 +96,10 @@ static int blk_queue_flags_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static ssize_t blk_queue_flags_store(struct file *file, const char __user *buf,
-				     size_t count, loff_t *ppos)
+static ssize_t queue_state_write(void *data, const char __user *buf,
+				 size_t count, loff_t *ppos)
 {
-	struct request_queue *q = file_inode(file)->i_private;
+	struct request_queue *q = data;
 	char opbuf[16] = { }, *op;
 
 	if (count >= sizeof(opbuf)) {
@@ -134,19 +123,6 @@ static ssize_t blk_queue_flags_store(struct file *file, const char __user *buf,
 	return count;
 }
 
-static int blk_queue_flags_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, blk_queue_flags_show, inode->i_private);
-}
-
-static const struct file_operations blk_queue_flags_fops = {
-	.open		= blk_queue_flags_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-	.write		= blk_queue_flags_store,
-};
-
 static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
 {
 	if (stat->nr_samples) {
@@ -157,9 +133,9 @@ static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
 	}
 }
 
-static int queue_poll_stat_show(struct seq_file *m, void *v)
+static int queue_poll_stat_show(void *data, struct seq_file *m)
 {
-	struct request_queue *q = m->private;
+	struct request_queue *q = data;
 	int bucket;
 
 	for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS/2; bucket++) {
@@ -174,18 +150,6 @@ static int queue_poll_stat_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int queue_poll_stat_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, queue_poll_stat_show, inode->i_private);
-}
-
-static const struct file_operations queue_poll_stat_fops = {
-	.open		= queue_poll_stat_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
 #define HCTX_STATE_NAME(name) [BLK_MQ_S_##name] = #name
 static const char *const hctx_state_name[] = {
 	HCTX_STATE_NAME(STOPPED),
@@ -196,9 +160,9 @@ static const char *const hctx_state_name[] = {
 };
 #undef HCTX_STATE_NAME
 
-static int hctx_state_show(struct seq_file *m, void *v)
+static int hctx_state_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	blk_flags_show(m, hctx->state, hctx_state_name,
 		       ARRAY_SIZE(hctx_state_name));
@@ -206,18 +170,6 @@ static int hctx_state_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int hctx_state_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_state_show, inode->i_private);
-}
-
-static const struct file_operations hctx_state_fops = {
-	.open		= hctx_state_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
 #define BLK_TAG_ALLOC_NAME(name) [BLK_TAG_ALLOC_##name] = #name
 static const char *const alloc_policy_name[] = {
 	BLK_TAG_ALLOC_NAME(FIFO),
@@ -235,9 +187,9 @@ static const char *const hctx_flag_name[] = {
 };
 #undef HCTX_FLAG_NAME
 
-static int hctx_flags_show(struct seq_file *m, void *v)
+static int hctx_flags_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 	const int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(hctx->flags);
 
 	seq_puts(m, "alloc_policy=");
@@ -254,18 +206,6 @@ static int hctx_flags_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int hctx_flags_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_flags_show, inode->i_private);
-}
-
-static const struct file_operations hctx_flags_fops = {
-	.open		= hctx_flags_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name
 static const char *const op_name[] = {
 	REQ_OP_NAME(READ),
@@ -383,38 +323,14 @@ static const struct seq_operations hctx_dispatch_seq_ops = {
 	.show	= blk_mq_debugfs_rq_show,
 };
 
-static int hctx_dispatch_open(struct inode *inode, struct file *file)
-{
-	return blk_mq_debugfs_seq_open(inode, file, &hctx_dispatch_seq_ops);
-}
-
-static const struct file_operations hctx_dispatch_fops = {
-	.open		= hctx_dispatch_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= seq_release,
-};
-
-static int hctx_ctx_map_show(struct seq_file *m, void *v)
+static int hctx_ctx_map_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	sbitmap_bitmap_show(&hctx->ctx_map, m);
 	return 0;
 }
 
-static int hctx_ctx_map_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_ctx_map_show, inode->i_private);
-}
-
-static const struct file_operations hctx_ctx_map_fops = {
-	.open		= hctx_ctx_map_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
 static void blk_mq_debugfs_tags_show(struct seq_file *m,
 				     struct blk_mq_tags *tags)
 {
@@ -432,9 +348,9 @@ static void blk_mq_debugfs_tags_show(struct seq_file *m,
 	}
 }
 
-static int hctx_tags_show(struct seq_file *m, void *v)
+static int hctx_tags_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 	struct request_queue *q = hctx->queue;
 	int res;
 
@@ -449,21 +365,9 @@ static int hctx_tags_show(struct seq_file *m, void *v)
 	return res;
 }
 
-static int hctx_tags_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_tags_show, inode->i_private);
-}
-
-static const struct file_operations hctx_tags_fops = {
-	.open		= hctx_tags_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_tags_bitmap_show(struct seq_file *m, void *v)
+static int hctx_tags_bitmap_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 	struct request_queue *q = hctx->queue;
 	int res;
 
@@ -478,21 +382,9 @@ static int hctx_tags_bitmap_show(struct seq_file *m, void *v)
 	return res;
 }
 
-static int hctx_tags_bitmap_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_tags_bitmap_show, inode->i_private);
-}
-
-static const struct file_operations hctx_tags_bitmap_fops = {
-	.open		= hctx_tags_bitmap_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_sched_tags_show(struct seq_file *m, void *v)
+static int hctx_sched_tags_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 	struct request_queue *q = hctx->queue;
 	int res;
 
@@ -507,21 +399,9 @@ static int hctx_sched_tags_show(struct seq_file *m, void *v)
 	return res;
 }
 
-static int hctx_sched_tags_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_sched_tags_show, inode->i_private);
-}
-
-static const struct file_operations hctx_sched_tags_fops = {
-	.open		= hctx_sched_tags_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_sched_tags_bitmap_show(struct seq_file *m, void *v)
+static int hctx_sched_tags_bitmap_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 	struct request_queue *q = hctx->queue;
 	int res;
 
@@ -536,21 +416,9 @@ static int hctx_sched_tags_bitmap_show(struct seq_file *m, void *v)
 	return res;
 }
 
-static int hctx_sched_tags_bitmap_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_sched_tags_bitmap_show, inode->i_private);
-}
-
-static const struct file_operations hctx_sched_tags_bitmap_fops = {
-	.open		= hctx_sched_tags_bitmap_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_io_poll_show(struct seq_file *m, void *v)
+static int hctx_io_poll_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	seq_printf(m, "considered=%lu\n", hctx->poll_considered);
 	seq_printf(m, "invoked=%lu\n", hctx->poll_invoked);
@@ -558,32 +426,18 @@ static int hctx_io_poll_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int hctx_io_poll_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_io_poll_show, inode->i_private);
-}
-
-static ssize_t hctx_io_poll_write(struct file *file, const char __user *buf,
+static ssize_t hctx_io_poll_write(void *data, const char __user *buf,
 				  size_t count, loff_t *ppos)
 {
-	struct seq_file *m = file->private_data;
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	hctx->poll_considered = hctx->poll_invoked = hctx->poll_success = 0;
 	return count;
 }
 
-static const struct file_operations hctx_io_poll_fops = {
-	.open		= hctx_io_poll_open,
-	.read		= seq_read,
-	.write		= hctx_io_poll_write,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_dispatched_show(struct seq_file *m, void *v)
+static int hctx_dispatched_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 	int i;
 
 	seq_printf(m, "%8u\t%lu\n", 0U, hctx->dispatched[0]);
@@ -598,16 +452,10 @@ static int hctx_dispatched_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int hctx_dispatched_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_dispatched_show, inode->i_private);
-}
-
-static ssize_t hctx_dispatched_write(struct file *file, const char __user *buf,
+static ssize_t hctx_dispatched_write(void *data, const char __user *buf,
 				     size_t count, loff_t *ppos)
 {
-	struct seq_file *m = file->private_data;
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 	int i;
 
 	for (i = 0; i < BLK_MQ_MAX_DISPATCH_ORDER; i++)
@@ -615,96 +463,48 @@ static ssize_t hctx_dispatched_write(struct file *file, const char __user *buf,
 	return count;
 }
 
-static const struct file_operations hctx_dispatched_fops = {
-	.open		= hctx_dispatched_open,
-	.read		= seq_read,
-	.write		= hctx_dispatched_write,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_queued_show(struct seq_file *m, void *v)
+static int hctx_queued_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	seq_printf(m, "%lu\n", hctx->queued);
 	return 0;
 }
 
-static int hctx_queued_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_queued_show, inode->i_private);
-}
-
-static ssize_t hctx_queued_write(struct file *file, const char __user *buf,
+static ssize_t hctx_queued_write(void *data, const char __user *buf,
 				 size_t count, loff_t *ppos)
 {
-	struct seq_file *m = file->private_data;
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	hctx->queued = 0;
 	return count;
 }
 
-static const struct file_operations hctx_queued_fops = {
-	.open		= hctx_queued_open,
-	.read		= seq_read,
-	.write		= hctx_queued_write,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_run_show(struct seq_file *m, void *v)
+static int hctx_run_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	seq_printf(m, "%lu\n", hctx->run);
 	return 0;
 }
 
-static int hctx_run_open(struct inode *inode, struct file *file)
+static ssize_t hctx_run_write(void *data, const char __user *buf, size_t count,
+			      loff_t *ppos)
 {
-	return single_open(file, hctx_run_show, inode->i_private);
-}
-
-static ssize_t hctx_run_write(struct file *file, const char __user *buf,
-				 size_t count, loff_t *ppos)
-{
-	struct seq_file *m = file->private_data;
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	hctx->run = 0;
 	return count;
 }
 
-static const struct file_operations hctx_run_fops = {
-	.open		= hctx_run_open,
-	.read		= seq_read,
-	.write		= hctx_run_write,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int hctx_active_show(struct seq_file *m, void *v)
+static int hctx_active_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_hw_ctx *hctx = m->private;
+	struct blk_mq_hw_ctx *hctx = data;
 
 	seq_printf(m, "%d\n", atomic_read(&hctx->nr_active));
 	return 0;
 }
 
-static int hctx_active_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, hctx_active_show, inode->i_private);
-}
-
-static const struct file_operations hctx_active_fops = {
-	.open		= hctx_active_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
 static void *ctx_rq_list_start(struct seq_file *m, loff_t *pos)
 	__acquires(&ctx->lock)
 {
@@ -735,140 +535,146 @@ static const struct seq_operations ctx_rq_list_seq_ops = {
 	.stop	= ctx_rq_list_stop,
 	.show	= blk_mq_debugfs_rq_show,
 };
-
-static int ctx_rq_list_open(struct inode *inode, struct file *file)
-{
-	return blk_mq_debugfs_seq_open(inode, file, &ctx_rq_list_seq_ops);
-}
-
-static const struct file_operations ctx_rq_list_fops = {
-	.open		= ctx_rq_list_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= seq_release,
-};
-
-static int ctx_dispatched_show(struct seq_file *m, void *v)
+static int ctx_dispatched_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_ctx *ctx = m->private;
+	struct blk_mq_ctx *ctx = data;
 
 	seq_printf(m, "%lu %lu\n", ctx->rq_dispatched[1], ctx->rq_dispatched[0]);
 	return 0;
 }
 
-static int ctx_dispatched_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, ctx_dispatched_show, inode->i_private);
-}
-
-static ssize_t ctx_dispatched_write(struct file *file, const char __user *buf,
+static ssize_t ctx_dispatched_write(void *data, const char __user *buf,
 				    size_t count, loff_t *ppos)
 {
-	struct seq_file *m = file->private_data;
-	struct blk_mq_ctx *ctx = m->private;
+	struct blk_mq_ctx *ctx = data;
 
 	ctx->rq_dispatched[0] = ctx->rq_dispatched[1] = 0;
 	return count;
 }
 
-static const struct file_operations ctx_dispatched_fops = {
-	.open		= ctx_dispatched_open,
-	.read		= seq_read,
-	.write		= ctx_dispatched_write,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int ctx_merged_show(struct seq_file *m, void *v)
+static int ctx_merged_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_ctx *ctx = m->private;
+	struct blk_mq_ctx *ctx = data;
 
 	seq_printf(m, "%lu\n", ctx->rq_merged);
 	return 0;
 }
 
-static int ctx_merged_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, ctx_merged_show, inode->i_private);
-}
-
-static ssize_t ctx_merged_write(struct file *file, const char __user *buf,
-				    size_t count, loff_t *ppos)
+static ssize_t ctx_merged_write(void *data, const char __user *buf,
+				size_t count, loff_t *ppos)
 {
-	struct seq_file *m = file->private_data;
-	struct blk_mq_ctx *ctx = m->private;
+	struct blk_mq_ctx *ctx = data;
 
 	ctx->rq_merged = 0;
 	return count;
 }
 
-static const struct file_operations ctx_merged_fops = {
-	.open		= ctx_merged_open,
-	.read		= seq_read,
-	.write		= ctx_merged_write,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
-static int ctx_completed_show(struct seq_file *m, void *v)
+static int ctx_completed_show(void *data, struct seq_file *m)
 {
-	struct blk_mq_ctx *ctx = m->private;
+	struct blk_mq_ctx *ctx = data;
 
 	seq_printf(m, "%lu %lu\n", ctx->rq_completed[1], ctx->rq_completed[0]);
 	return 0;
 }
 
-static int ctx_completed_open(struct inode *inode, struct file *file)
+static ssize_t ctx_completed_write(void *data, const char __user *buf,
+				   size_t count, loff_t *ppos)
 {
-	return single_open(file, ctx_completed_show, inode->i_private);
+	struct blk_mq_ctx *ctx = data;
+
+	ctx->rq_completed[0] = ctx->rq_completed[1] = 0;
+	return count;
 }
 
-static ssize_t ctx_completed_write(struct file *file, const char __user *buf,
-				   size_t count, loff_t *ppos)
+static int blk_mq_debugfs_show(struct seq_file *m, void *v)
+{
+	const struct blk_mq_debugfs_attr *attr = m->private;
+	void *data = d_inode(m->file->f_path.dentry->d_parent)->i_private;
+
+	return attr->show(data, m);
+}
+
+static ssize_t blk_mq_debugfs_write(struct file *file, const char __user *buf,
+				    size_t count, loff_t *ppos)
 {
 	struct seq_file *m = file->private_data;
-	struct blk_mq_ctx *ctx = m->private;
+	const struct blk_mq_debugfs_attr *attr = m->private;
+	void *data = d_inode(file->f_path.dentry->d_parent)->i_private;
 
-	ctx->rq_completed[0] = ctx->rq_completed[1] = 0;
-	return count;
+	if (!attr->write)
+		return -EPERM;
+
+	return attr->write(data, buf, count, ppos);
+}
+
+static int blk_mq_debugfs_open(struct inode *inode, struct file *file)
+{
+	const struct blk_mq_debugfs_attr *attr = inode->i_private;
+	void *data = d_inode(file->f_path.dentry->d_parent)->i_private;
+	struct seq_file *m;
+	int ret;
+
+	if (attr->seq_ops) {
+		ret = seq_open(file, attr->seq_ops);
+		if (!ret) {
+			m = file->private_data;
+			m->private = data;
+		}
+		return ret;
+	}
+
+	if (WARN_ON_ONCE(!attr->show))
+		return -EPERM;
+
+	return single_open(file, blk_mq_debugfs_show, inode->i_private);
 }
 
-static const struct file_operations ctx_completed_fops = {
-	.open		= ctx_completed_open,
+static int blk_mq_debugfs_release(struct inode *inode, struct file *file)
+{
+	const struct blk_mq_debugfs_attr *attr = inode->i_private;
+
+	if (attr->show)
+		return single_release(inode, file);
+	else
+		return seq_release(inode, file);
+}
+
+const struct file_operations blk_mq_debugfs_fops = {
+	.open		= blk_mq_debugfs_open,
 	.read		= seq_read,
-	.write		= ctx_completed_write,
+	.write		= blk_mq_debugfs_write,
 	.llseek		= seq_lseek,
-	.release	= single_release,
+	.release	= blk_mq_debugfs_release,
 };
 
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
-	{"poll_stat", 0400, &queue_poll_stat_fops},
-	{"state", 0600, &blk_queue_flags_fops},
+	{"poll_stat", 0400, queue_poll_stat_show},
+	{"state", 0600, queue_state_show, queue_state_write},
 	{},
 };
 
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
-	{"state", 0400, &hctx_state_fops},
-	{"flags", 0400, &hctx_flags_fops},
-	{"dispatch", 0400, &hctx_dispatch_fops},
-	{"ctx_map", 0400, &hctx_ctx_map_fops},
-	{"tags", 0400, &hctx_tags_fops},
-	{"tags_bitmap", 0400, &hctx_tags_bitmap_fops},
-	{"sched_tags", 0400, &hctx_sched_tags_fops},
-	{"sched_tags_bitmap", 0400, &hctx_sched_tags_bitmap_fops},
-	{"io_poll", 0600, &hctx_io_poll_fops},
-	{"dispatched", 0600, &hctx_dispatched_fops},
-	{"queued", 0600, &hctx_queued_fops},
-	{"run", 0600, &hctx_run_fops},
-	{"active", 0400, &hctx_active_fops},
+	{"state", 0400, hctx_state_show},
+	{"flags", 0400, hctx_flags_show},
+	{"dispatch", 0400, .seq_ops = &hctx_dispatch_seq_ops},
+	{"ctx_map", 0400, hctx_ctx_map_show},
+	{"tags", 0400, hctx_tags_show},
+	{"tags_bitmap", 0400, hctx_tags_bitmap_show},
+	{"sched_tags", 0400, hctx_sched_tags_show},
+	{"sched_tags_bitmap", 0400, hctx_sched_tags_bitmap_show},
+	{"io_poll", 0600, hctx_io_poll_show, hctx_io_poll_write},
+	{"dispatched", 0600, hctx_dispatched_show, hctx_dispatched_write},
+	{"queued", 0600, hctx_queued_show, hctx_queued_write},
+	{"run", 0600, hctx_run_show, hctx_run_write},
+	{"active", 0400, hctx_active_show},
 	{},
 };
 
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
-	{"rq_list", 0400, &ctx_rq_list_fops},
-	{"dispatched", 0600, &ctx_dispatched_fops},
-	{"merged", 0600, &ctx_merged_fops},
-	{"completed", 0600, &ctx_completed_fops},
+	{"rq_list", 0400, .seq_ops = &ctx_rq_list_seq_ops},
+	{"dispatched", 0600, ctx_dispatched_show, ctx_dispatched_write},
+	{"merged", 0600, ctx_merged_show, ctx_merged_write},
+	{"completed", 0600, ctx_completed_show, ctx_completed_write},
 	{},
 };
 
@@ -900,11 +706,13 @@ void blk_mq_debugfs_unregister(struct request_queue *q)
 }
 
 static bool debugfs_create_files(struct dentry *parent, void *data,
-				const struct blk_mq_debugfs_attr *attr)
+				 const struct blk_mq_debugfs_attr *attr)
 {
+	d_inode(parent)->i_private = data;
+
 	for (; attr->name; attr++) {
 		if (!debugfs_create_file(attr->name, attr->mode, parent,
-					 data, attr->fops))
+					 (void *)attr, &blk_mq_debugfs_fops))
 			return false;
 	}
 	return true;
-- 
2.12.2

[PATCH v2 07/12] blk-mq: Do not invoke queue operations on a dead queue

[Omar Sandoval]

From: Bart Van Assche <bart.vanassche@sandisk.com>

In commit e869b5462f83 ("blk-mq: Unregister debugfs attributes
earlier"), we shuffled the debugfs cleanup around so that the "state"
attribute was removed before we freed the blk-mq data structures.
However, later changes are going to undo that, so we need to explicitly
disallow running a dead queue.

[Omar: rebased and updated commit message]
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
---
 block/blk-mq-debugfs.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 1579af6fcbed..347fbb8e059c 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -102,6 +102,14 @@ static ssize_t queue_state_write(void *data, const char __user *buf,
 	struct request_queue *q = data;
 	char opbuf[16] = { }, *op;
 
+	/*
+	 * The "state" attribute is removed after blk_cleanup_queue() has called
+	 * blk_mq_free_queue(). Return if QUEUE_FLAG_DEAD has been set to avoid
+	 * triggering a use-after-free.
+	 */
+	if (blk_queue_dead(q))
+		return -ENOENT;
+
 	if (count >= sizeof(opbuf)) {
 		pr_err("%s: operation too long\n", __func__);
 		goto inval;
-- 
2.12.2

[PATCH v2 08/12] blk-mq: move debugfs declarations to a separate header file

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Preparation for adding more declarations.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-core.c       |  1 +
 block/blk-mq-debugfs.c |  1 +
 block/blk-mq-debugfs.h | 29 +++++++++++++++++++++++++++++
 block/blk-mq-sysfs.c   |  1 +
 block/blk-mq.h         | 28 ----------------------------
 block/blk-sysfs.c      |  1 +
 6 files changed, 33 insertions(+), 28 deletions(-)
 create mode 100644 block/blk-mq-debugfs.h

diff --git a/block/blk-core.c b/block/blk-core.c
index 24886b69690f..acdca6536562 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -40,6 +40,7 @@
 
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-sched.h"
 #include "blk-wbt.h"
 
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 347fbb8e059c..1dc1847b5363 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -21,6 +21,7 @@
 #include <linux/blk-mq.h>
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-tag.h"
 
 struct blk_mq_debugfs_attr {
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
new file mode 100644
index 000000000000..00b0f71d0ae9
--- /dev/null
+++ b/block/blk-mq-debugfs.h
@@ -0,0 +1,29 @@
+#ifndef INT_BLK_MQ_DEBUGFS_H
+#define INT_BLK_MQ_DEBUGFS_H
+
+#ifdef CONFIG_BLK_DEBUG_FS
+int blk_mq_debugfs_register(struct request_queue *q);
+void blk_mq_debugfs_unregister(struct request_queue *q);
+int blk_mq_debugfs_register_mq(struct request_queue *q);
+void blk_mq_debugfs_unregister_mq(struct request_queue *q);
+#else
+static inline int blk_mq_debugfs_register(struct request_queue *q)
+{
+	return 0;
+}
+
+static inline void blk_mq_debugfs_unregister(struct request_queue *q)
+{
+}
+
+static inline int blk_mq_debugfs_register_mq(struct request_queue *q)
+{
+	return 0;
+}
+
+static inline void blk_mq_debugfs_unregister_mq(struct request_queue *q)
+{
+}
+#endif
+
+#endif
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index ec0afdf765e3..71a237a90d43 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -11,6 +11,7 @@
 
 #include <linux/blk-mq.h>
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-tag.h"
 
 static void blk_mq_sysfs_release(struct kobject *kobj)
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 2814a14e529c..cc67b48e3551 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -83,34 +83,6 @@ extern int blk_mq_sysfs_register(struct request_queue *q);
 extern void blk_mq_sysfs_unregister(struct request_queue *q);
 extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
 
-/*
- * debugfs helpers
- */
-#ifdef CONFIG_BLK_DEBUG_FS
-int blk_mq_debugfs_register(struct request_queue *q);
-void blk_mq_debugfs_unregister(struct request_queue *q);
-int blk_mq_debugfs_register_mq(struct request_queue *q);
-void blk_mq_debugfs_unregister_mq(struct request_queue *q);
-#else
-static inline int blk_mq_debugfs_register(struct request_queue *q)
-{
-	return 0;
-}
-
-static inline void blk_mq_debugfs_unregister(struct request_queue *q)
-{
-}
-
-static inline int blk_mq_debugfs_register_mq(struct request_queue *q)
-{
-	return 0;
-}
-
-static inline void blk_mq_debugfs_unregister_mq(struct request_queue *q)
-{
-}
-#endif
-
 extern void blk_mq_rq_timed_out(struct request *req, bool reserved);
 
 void blk_mq_release(struct request_queue *q);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 3f37813ccbaf..9995355121d7 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -13,6 +13,7 @@
 
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-wbt.h"
 
 struct queue_sysfs_entry {
-- 
2.12.2

[PATCH v2 09/12] blk-mq: untangle debugfs and sysfs

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Originally, I tied debugfs registration/unregistration together with
sysfs. There's no reason to do this, and it's getting in the way of
letting schedulers define their own debugfs attributes. Instead, tie the
debugfs registration to the lifetime of the structures themselves.

The saner lifetimes mean we can also get rid of the extra mq directory
and move everything one level up. I.e., nvme0n1/mq/hctx0/tags is now
just nvme0n1/hctx0/tags.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-core.c       |   9 +---
 block/blk-mq-debugfs.c | 110 ++++++++++++++++++++++++++++---------------------
 block/blk-mq-debugfs.h |  21 ++++++++--
 block/blk-mq-sysfs.c   |  11 -----
 block/blk-mq.c         |   7 ++++
 block/blk-sysfs.c      |   2 +
 include/linux/blk-mq.h |   4 ++
 include/linux/blkdev.h |   1 -
 8 files changed, 94 insertions(+), 71 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index acdca6536562..c580b0138a7f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -40,7 +40,6 @@
 
 #include "blk.h"
 #include "blk-mq.h"
-#include "blk-mq-debugfs.h"
 #include "blk-mq-sched.h"
 #include "blk-wbt.h"
 
@@ -562,13 +561,9 @@ void blk_cleanup_queue(struct request_queue *q)
 	 * prevent that q->request_fn() gets invoked after draining finished.
 	 */
 	blk_freeze_queue(q);
-	if (!q->mq_ops) {
-		spin_lock_irq(lock);
+	spin_lock_irq(lock);
+	if (!q->mq_ops)
 		__blk_drain_queue(q, true);
-	} else {
-		blk_mq_debugfs_unregister_mq(q);
-		spin_lock_irq(lock);
-	}
 	queue_flag_set(QUEUE_FLAG_DEAD, q);
 	spin_unlock_irq(lock);
 
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 1dc1847b5363..260cf76e0705 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -687,19 +687,46 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
 	{},
 };
 
+static bool debugfs_create_files(struct dentry *parent, void *data,
+				 const struct blk_mq_debugfs_attr *attr)
+{
+	d_inode(parent)->i_private = data;
+
+	for (; attr->name; attr++) {
+		if (!debugfs_create_file(attr->name, attr->mode, parent,
+					 (void *)attr, &blk_mq_debugfs_fops))
+			return false;
+	}
+	return true;
+}
+
 int blk_mq_debugfs_register(struct request_queue *q)
 {
+	struct blk_mq_hw_ctx *hctx;
+	int i;
+
 	if (!blk_debugfs_root)
 		return -ENOENT;
 
 	q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent),
 					    blk_debugfs_root);
 	if (!q->debugfs_dir)
-		goto err;
+		return -ENOMEM;
 
-	if (blk_mq_debugfs_register_mq(q))
+	if (!debugfs_create_files(q->debugfs_dir, q,
+				  blk_mq_debugfs_queue_attrs))
 		goto err;
 
+	/*
+	 * blk_mq_init_hctx() attempted to do this already, but q->debugfs_dir
+	 * didn't exist yet (because we don't know what to name the directory
+	 * until the queue is registered to a gendisk).
+	 */
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (!hctx->debugfs_dir && blk_mq_debugfs_register_hctx(q, hctx))
+			goto err;
+	}
+
 	return 0;
 
 err:
@@ -710,32 +737,17 @@ int blk_mq_debugfs_register(struct request_queue *q)
 void blk_mq_debugfs_unregister(struct request_queue *q)
 {
 	debugfs_remove_recursive(q->debugfs_dir);
-	q->mq_debugfs_dir = NULL;
 	q->debugfs_dir = NULL;
 }
 
-static bool debugfs_create_files(struct dentry *parent, void *data,
-				 const struct blk_mq_debugfs_attr *attr)
-{
-	d_inode(parent)->i_private = data;
-
-	for (; attr->name; attr++) {
-		if (!debugfs_create_file(attr->name, attr->mode, parent,
-					 (void *)attr, &blk_mq_debugfs_fops))
-			return false;
-	}
-	return true;
-}
-
-static int blk_mq_debugfs_register_ctx(struct request_queue *q,
-				       struct blk_mq_ctx *ctx,
-				       struct dentry *hctx_dir)
+static int blk_mq_debugfs_register_ctx(struct blk_mq_hw_ctx *hctx,
+				       struct blk_mq_ctx *ctx)
 {
 	struct dentry *ctx_dir;
 	char name[20];
 
 	snprintf(name, sizeof(name), "cpu%u", ctx->cpu);
-	ctx_dir = debugfs_create_dir(name, hctx_dir);
+	ctx_dir = debugfs_create_dir(name, hctx->debugfs_dir);
 	if (!ctx_dir)
 		return -ENOMEM;
 
@@ -745,59 +757,61 @@ static int blk_mq_debugfs_register_ctx(struct request_queue *q,
 	return 0;
 }
 
-static int blk_mq_debugfs_register_hctx(struct request_queue *q,
-					struct blk_mq_hw_ctx *hctx)
+int blk_mq_debugfs_register_hctx(struct request_queue *q,
+				 struct blk_mq_hw_ctx *hctx)
 {
 	struct blk_mq_ctx *ctx;
-	struct dentry *hctx_dir;
 	char name[20];
 	int i;
 
+	if (!q->debugfs_dir)
+		return -ENOENT;
+
 	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);
-	hctx_dir = debugfs_create_dir(name, q->mq_debugfs_dir);
-	if (!hctx_dir)
+	hctx->debugfs_dir = debugfs_create_dir(name, q->debugfs_dir);
+	if (!hctx->debugfs_dir)
 		return -ENOMEM;
 
-	if (!debugfs_create_files(hctx_dir, hctx, blk_mq_debugfs_hctx_attrs))
-		return -ENOMEM;
+	if (!debugfs_create_files(hctx->debugfs_dir, hctx,
+				  blk_mq_debugfs_hctx_attrs))
+		goto err;
 
 	hctx_for_each_ctx(hctx, ctx, i) {
-		if (blk_mq_debugfs_register_ctx(q, ctx, hctx_dir))
-			return -ENOMEM;
+		if (blk_mq_debugfs_register_ctx(hctx, ctx))
+			goto err;
 	}
 
 	return 0;
+
+err:
+	blk_mq_debugfs_unregister_hctx(hctx);
+	return -ENOMEM;
+}
+
+void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)
+{
+	debugfs_remove_recursive(hctx->debugfs_dir);
+	hctx->debugfs_dir = NULL;
 }
 
-int blk_mq_debugfs_register_mq(struct request_queue *q)
+int blk_mq_debugfs_register_hctxs(struct request_queue *q)
 {
 	struct blk_mq_hw_ctx *hctx;
 	int i;
 
-	if (!q->debugfs_dir)
-		return -ENOENT;
-
-	q->mq_debugfs_dir = debugfs_create_dir("mq", q->debugfs_dir);
-	if (!q->mq_debugfs_dir)
-		goto err;
-
-	if (!debugfs_create_files(q->mq_debugfs_dir, q, blk_mq_debugfs_queue_attrs))
-		goto err;
-
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (blk_mq_debugfs_register_hctx(q, hctx))
-			goto err;
+			return -ENOMEM;
 	}
 
 	return 0;
-
-err:
-	blk_mq_debugfs_unregister_mq(q);
-	return -ENOMEM;
 }
 
-void blk_mq_debugfs_unregister_mq(struct request_queue *q)
+void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
 {
-	debugfs_remove_recursive(q->mq_debugfs_dir);
-	q->mq_debugfs_dir = NULL;
+	struct blk_mq_hw_ctx *hctx;
+	int i;
+
+	queue_for_each_hw_ctx(q, hctx, i)
+		blk_mq_debugfs_unregister_hctx(hctx);
 }
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index 00b0f71d0ae9..596e9b16d3d1 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -4,8 +4,11 @@
 #ifdef CONFIG_BLK_DEBUG_FS
 int blk_mq_debugfs_register(struct request_queue *q);
 void blk_mq_debugfs_unregister(struct request_queue *q);
-int blk_mq_debugfs_register_mq(struct request_queue *q);
-void blk_mq_debugfs_unregister_mq(struct request_queue *q);
+int blk_mq_debugfs_register_hctx(struct request_queue *q,
+				 struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx);
+int blk_mq_debugfs_register_hctxs(struct request_queue *q);
+void blk_mq_debugfs_unregister_hctxs(struct request_queue *q);
 #else
 static inline int blk_mq_debugfs_register(struct request_queue *q)
 {
@@ -16,12 +19,22 @@ static inline void blk_mq_debugfs_unregister(struct request_queue *q)
 {
 }
 
-static inline int blk_mq_debugfs_register_mq(struct request_queue *q)
+static inline int blk_mq_debugfs_register_hctx(struct request_queue *q,
+					       struct blk_mq_hw_ctx *hctx)
 {
 	return 0;
 }
 
-static inline void blk_mq_debugfs_unregister_mq(struct request_queue *q)
+static inline void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline int blk_mq_debugfs_register_hctxs(struct request_queue *q)
+{
+	return 0;
+}
+
+static inline void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
 {
 }
 #endif
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 71a237a90d43..79969c3c234f 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -11,7 +11,6 @@
 
 #include <linux/blk-mq.h>
 #include "blk-mq.h"
-#include "blk-mq-debugfs.h"
 #include "blk-mq-tag.h"
 
 static void blk_mq_sysfs_release(struct kobject *kobj)
@@ -259,8 +258,6 @@ static void __blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
 	queue_for_each_hw_ctx(q, hctx, i)
 		blk_mq_unregister_hctx(hctx);
 
-	blk_mq_debugfs_unregister_mq(q);
-
 	kobject_uevent(&q->mq_kobj, KOBJ_REMOVE);
 	kobject_del(&q->mq_kobj);
 	kobject_put(&dev->kobj);
@@ -319,8 +316,6 @@ int __blk_mq_register_dev(struct device *dev, struct request_queue *q)
 
 	kobject_uevent(&q->mq_kobj, KOBJ_ADD);
 
-	blk_mq_debugfs_register(q);
-
 	queue_for_each_hw_ctx(q, hctx, i) {
 		ret = blk_mq_register_hctx(hctx);
 		if (ret)
@@ -336,8 +331,6 @@ int __blk_mq_register_dev(struct device *dev, struct request_queue *q)
 	while (--i >= 0)
 		blk_mq_unregister_hctx(q->queue_hw_ctx[i]);
 
-	blk_mq_debugfs_unregister_mq(q);
-
 	kobject_uevent(&q->mq_kobj, KOBJ_REMOVE);
 	kobject_del(&q->mq_kobj);
 	kobject_put(&dev->kobj);
@@ -365,8 +358,6 @@ void blk_mq_sysfs_unregister(struct request_queue *q)
 	if (!q->mq_sysfs_init_done)
 		goto unlock;
 
-	blk_mq_debugfs_unregister_mq(q);
-
 	queue_for_each_hw_ctx(q, hctx, i)
 		blk_mq_unregister_hctx(hctx);
 
@@ -383,8 +374,6 @@ int blk_mq_sysfs_register(struct request_queue *q)
 	if (!q->mq_sysfs_init_done)
 		goto unlock;
 
-	blk_mq_debugfs_register_mq(q);
-
 	queue_for_each_hw_ctx(q, hctx, i) {
 		ret = blk_mq_register_hctx(hctx);
 		if (ret)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index bf90684a007a..f54467a84d9a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -31,6 +31,7 @@
 #include <linux/blk-mq.h>
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-tag.h"
 #include "blk-stat.h"
 #include "blk-wbt.h"
@@ -1851,6 +1852,8 @@ static void blk_mq_exit_hctx(struct request_queue *q,
 {
 	unsigned flush_start_tag = set->queue_depth;
 
+	blk_mq_debugfs_unregister_hctx(hctx);
+
 	blk_mq_tag_idle(hctx);
 
 	if (set->ops->exit_request)
@@ -1941,6 +1944,8 @@ static int blk_mq_init_hctx(struct request_queue *q,
 	if (hctx->flags & BLK_MQ_F_BLOCKING)
 		init_srcu_struct(&hctx->queue_rq_srcu);
 
+	blk_mq_debugfs_register_hctx(q, hctx);
+
 	return 0;
 
  free_fq:
@@ -2378,6 +2383,7 @@ static void blk_mq_queue_reinit(struct request_queue *q,
 {
 	WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
 
+	blk_mq_debugfs_unregister_hctxs(q);
 	blk_mq_sysfs_unregister(q);
 
 	/*
@@ -2389,6 +2395,7 @@ static void blk_mq_queue_reinit(struct request_queue *q,
 	blk_mq_map_swqueue(q, online_mask);
 
 	blk_mq_sysfs_register(q);
+	blk_mq_debugfs_register_hctxs(q);
 }
 
 /*
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 9995355121d7..504fee940052 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -890,6 +890,8 @@ int blk_register_queue(struct gendisk *disk)
 	if (q->mq_ops)
 		__blk_mq_register_dev(dev, q);
 
+	blk_mq_debugfs_register(q);
+
 	kobject_uevent(&q->kobj, KOBJ_ADD);
 
 	wbt_enable_default(q);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index f3e5e1de1bdb..7c2fc881fe09 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -57,6 +57,10 @@ struct blk_mq_hw_ctx {
 	unsigned long		poll_considered;
 	unsigned long		poll_invoked;
 	unsigned long		poll_success;
+
+#ifdef CONFIG_BLK_DEBUG_FS
+	struct dentry		*debugfs_dir;
+#endif
 };
 
 struct blk_mq_tag_set {
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 83d28623645f..b49a79a29e58 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -579,7 +579,6 @@ struct request_queue {
 
 #ifdef CONFIG_BLK_DEBUG_FS
 	struct dentry		*debugfs_dir;
-	struct dentry		*mq_debugfs_dir;
 #endif
 
 	bool			mq_sysfs_init_done;
-- 
2.12.2

[PATCH v2 10/12] blk-mq-debugfs: allow schedulers to register debugfs attributes

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

This provides the infrastructure for schedulers to expose their internal
state through debugfs. We add a list of queue attributes and a list of
hctx attributes to struct elevator_type and wire them up when switching
schedulers.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c   | 74 ++++++++++++++++++++++++++++++++++++++++++------
 block/blk-mq-debugfs.h   | 34 ++++++++++++++++++++++
 block/blk-mq-sched.c     | 24 ++++++++++------
 include/linux/blk-mq.h   |  1 +
 include/linux/blkdev.h   |  1 +
 include/linux/elevator.h |  7 +++++
 6 files changed, 124 insertions(+), 17 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 260cf76e0705..a3b887109310 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -24,15 +24,6 @@
 #include "blk-mq-debugfs.h"
 #include "blk-mq-tag.h"
 
-struct blk_mq_debugfs_attr {
-	const char *name;
-	umode_t mode;
-	int (*show)(void *, struct seq_file *);
-	ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
-	/* Set either .show or .seq_ops. */
-	const struct seq_operations *seq_ops;
-};
-
 static int blk_flags_show(struct seq_file *m, const unsigned long flags,
 			  const char *const *flag_name, int flag_name_count)
 {
@@ -725,6 +716,9 @@ int blk_mq_debugfs_register(struct request_queue *q)
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (!hctx->debugfs_dir && blk_mq_debugfs_register_hctx(q, hctx))
 			goto err;
+		if (q->elevator && !hctx->sched_debugfs_dir &&
+		    blk_mq_debugfs_register_sched_hctx(q, hctx))
+			goto err;
 	}
 
 	return 0;
@@ -737,6 +731,7 @@ int blk_mq_debugfs_register(struct request_queue *q)
 void blk_mq_debugfs_unregister(struct request_queue *q)
 {
 	debugfs_remove_recursive(q->debugfs_dir);
+	q->sched_debugfs_dir = NULL;
 	q->debugfs_dir = NULL;
 }
 
@@ -791,6 +786,7 @@ int blk_mq_debugfs_register_hctx(struct request_queue *q,
 void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)
 {
 	debugfs_remove_recursive(hctx->debugfs_dir);
+	hctx->sched_debugfs_dir = NULL;
 	hctx->debugfs_dir = NULL;
 }
 
@@ -815,3 +811,63 @@ void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
 	queue_for_each_hw_ctx(q, hctx, i)
 		blk_mq_debugfs_unregister_hctx(hctx);
 }
+
+int blk_mq_debugfs_register_sched(struct request_queue *q)
+{
+	struct elevator_type *e = q->elevator->type;
+
+	if (!q->debugfs_dir)
+		return -ENOENT;
+
+	if (!e->queue_debugfs_attrs)
+		return 0;
+
+	q->sched_debugfs_dir = debugfs_create_dir("sched", q->debugfs_dir);
+	if (!q->sched_debugfs_dir)
+		return -ENOMEM;
+
+	if (!debugfs_create_files(q->sched_debugfs_dir, q,
+				  e->queue_debugfs_attrs))
+		goto err;
+
+	return 0;
+
+err:
+	blk_mq_debugfs_unregister_sched(q);
+	return -ENOMEM;
+}
+
+void blk_mq_debugfs_unregister_sched(struct request_queue *q)
+{
+	debugfs_remove_recursive(q->sched_debugfs_dir);
+	q->sched_debugfs_dir = NULL;
+}
+
+int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
+				       struct blk_mq_hw_ctx *hctx)
+{
+	struct elevator_type *e = q->elevator->type;
+
+	if (!hctx->debugfs_dir)
+		return -ENOENT;
+
+	if (!e->hctx_debugfs_attrs)
+		return 0;
+
+	hctx->sched_debugfs_dir = debugfs_create_dir("sched",
+						     hctx->debugfs_dir);
+	if (!hctx->sched_debugfs_dir)
+		return -ENOMEM;
+
+	if (!debugfs_create_files(hctx->sched_debugfs_dir, hctx,
+				  e->hctx_debugfs_attrs))
+		return -ENOMEM;
+
+	return 0;
+}
+
+void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
+{
+	debugfs_remove_recursive(hctx->sched_debugfs_dir);
+	hctx->sched_debugfs_dir = NULL;
+}
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index 596e9b16d3d1..29ecb43aa412 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -2,6 +2,15 @@
 #define INT_BLK_MQ_DEBUGFS_H
 
 #ifdef CONFIG_BLK_DEBUG_FS
+struct blk_mq_debugfs_attr {
+	const char *name;
+	umode_t mode;
+	int (*show)(void *, struct seq_file *);
+	ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
+	/* Set either .show or .seq_ops. */
+	const struct seq_operations *seq_ops;
+};
+
 int blk_mq_debugfs_register(struct request_queue *q);
 void blk_mq_debugfs_unregister(struct request_queue *q);
 int blk_mq_debugfs_register_hctx(struct request_queue *q,
@@ -9,6 +18,12 @@ int blk_mq_debugfs_register_hctx(struct request_queue *q,
 void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx);
 int blk_mq_debugfs_register_hctxs(struct request_queue *q);
 void blk_mq_debugfs_unregister_hctxs(struct request_queue *q);
+
+int blk_mq_debugfs_register_sched(struct request_queue *q);
+void blk_mq_debugfs_unregister_sched(struct request_queue *q);
+int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
+				       struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx);
 #else
 static inline int blk_mq_debugfs_register(struct request_queue *q)
 {
@@ -37,6 +52,25 @@ static inline int blk_mq_debugfs_register_hctxs(struct request_queue *q)
 static inline void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
 {
 }
+
+static inline int blk_mq_debugfs_register_sched(struct request_queue *q)
+{
+	return 0;
+}
+
+static inline void blk_mq_debugfs_unregister_sched(struct request_queue *q)
+{
+}
+
+static inline int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
+						     struct blk_mq_hw_ctx *hctx)
+{
+	return 0;
+}
+
+static inline void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
+{
+}
 #endif
 
 #endif
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 8b361e192e8a..4a8f569f1d21 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -11,6 +11,7 @@
 
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-sched.h"
 #include "blk-mq-tag.h"
 #include "blk-wbt.h"
@@ -476,6 +477,8 @@ int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
 		}
 	}
 
+	blk_mq_debugfs_register_sched_hctx(q, hctx);
+
 	return 0;
 }
 
@@ -487,6 +490,8 @@ void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
 	if (!e)
 		return;
 
+	blk_mq_debugfs_unregister_sched_hctx(hctx);
+
 	if (e->type->ops.mq.exit_hctx && hctx->sched_data) {
 		e->type->ops.mq.exit_hctx(hctx, hctx_idx);
 		hctx->sched_data = NULL;
@@ -523,8 +528,10 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 	if (ret)
 		goto err;
 
-	if (e->ops.mq.init_hctx) {
-		queue_for_each_hw_ctx(q, hctx, i) {
+	blk_mq_debugfs_register_sched(q);
+
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (e->ops.mq.init_hctx) {
 			ret = e->ops.mq.init_hctx(hctx, i);
 			if (ret) {
 				eq = q->elevator;
@@ -533,6 +540,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 				return ret;
 			}
 		}
+		blk_mq_debugfs_register_sched_hctx(q, hctx);
 	}
 
 	return 0;
@@ -548,14 +556,14 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
 	struct blk_mq_hw_ctx *hctx;
 	unsigned int i;
 
-	if (e->type->ops.mq.exit_hctx) {
-		queue_for_each_hw_ctx(q, hctx, i) {
-			if (hctx->sched_data) {
-				e->type->ops.mq.exit_hctx(hctx, i);
-				hctx->sched_data = NULL;
-			}
+	queue_for_each_hw_ctx(q, hctx, i) {
+		blk_mq_debugfs_unregister_sched_hctx(hctx);
+		if (e->type->ops.mq.exit_hctx && hctx->sched_data) {
+			e->type->ops.mq.exit_hctx(hctx, i);
+			hctx->sched_data = NULL;
 		}
 	}
+	blk_mq_debugfs_unregister_sched(q);
 	if (e->type->ops.mq.exit_sched)
 		e->type->ops.mq.exit_sched(e);
 	blk_mq_sched_tags_teardown(q);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 7c2fc881fe09..863409266eb7 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -60,6 +60,7 @@ struct blk_mq_hw_ctx {
 
 #ifdef CONFIG_BLK_DEBUG_FS
 	struct dentry		*debugfs_dir;
+	struct dentry		*sched_debugfs_dir;
 #endif
 };
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b49a79a29e58..80ae958717a1 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -579,6 +579,7 @@ struct request_queue {
 
 #ifdef CONFIG_BLK_DEBUG_FS
 	struct dentry		*debugfs_dir;
+	struct dentry		*sched_debugfs_dir;
 #endif
 
 	bool			mq_sysfs_init_done;
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 3a216318ae73..baaa12cd4dd9 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -8,6 +8,9 @@
 
 struct io_cq;
 struct elevator_type;
+#ifdef CONFIG_BLK_DEBUG_FS
+struct blk_mq_debugfs_attr;
+#endif
 
 /*
  * Return values from elevator merger
@@ -144,6 +147,10 @@ struct elevator_type
 	char elevator_name[ELV_NAME_MAX];
 	struct module *elevator_owner;
 	bool uses_mq;
+#ifdef CONFIG_BLK_DEBUG_FS
+	const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
+	const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
+#endif
 
 	/* managed by elevator core */
 	char icq_cache_name[ELV_NAME_MAX + 5];	/* elvname + "_io_cq" */
-- 
2.12.2

[PATCH v2 11/12] kyber: add debugfs attributes

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Expose the domain token pools, asynchronous sbitmap depth, domain
request lists, and batching state.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c |   3 +-
 block/blk-mq-debugfs.h |   2 +
 block/kyber-iosched.c  | 130 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 134 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index a3b887109310..8ec738f872e5 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -267,7 +267,7 @@ static const char *const rqf_name[] = {
 };
 #undef RQF_NAME
 
-static int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
+int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
 {
 	struct request *rq = list_entry_rq(v);
 	const struct blk_mq_ops *const mq_ops = rq->q->mq_ops;
@@ -291,6 +291,7 @@ static int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
 	seq_puts(m, "}\n");
 	return 0;
 }
+EXPORT_SYMBOL_GPL(blk_mq_debugfs_rq_show);
 
 static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
 	__acquires(&hctx->lock)
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index 29ecb43aa412..7c67f813a294 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -11,6 +11,8 @@ struct blk_mq_debugfs_attr {
 	const struct seq_operations *seq_ops;
 };
 
+int blk_mq_debugfs_rq_show(struct seq_file *m, void *v);
+
 int blk_mq_debugfs_register(struct request_queue *q);
 void blk_mq_debugfs_unregister(struct request_queue *q);
 int blk_mq_debugfs_register_hctx(struct request_queue *q,
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index 3b0090bc5dd1..b9faabc75fdb 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -26,6 +26,7 @@
 
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-sched.h"
 #include "blk-mq-tag.h"
 #include "blk-stat.h"
@@ -683,6 +684,131 @@ static struct elv_fs_entry kyber_sched_attrs[] = {
 };
 #undef KYBER_LAT_ATTR
 
+#ifdef CONFIG_BLK_DEBUG_FS
+#define KYBER_DEBUGFS_DOMAIN_ATTRS(domain, name)			\
+static int kyber_##name##_tokens_show(void *data, struct seq_file *m)	\
+{									\
+	struct request_queue *q = data;					\
+	struct kyber_queue_data *kqd = q->elevator->elevator_data;	\
+									\
+	sbitmap_queue_show(&kqd->domain_tokens[domain], m);		\
+	return 0;							\
+}									\
+									\
+static void *kyber_##name##_rqs_start(struct seq_file *m, loff_t *pos)	\
+	__acquires(&khd->lock)						\
+{									\
+	struct blk_mq_hw_ctx *hctx = m->private;			\
+	struct kyber_hctx_data *khd = hctx->sched_data;			\
+									\
+	spin_lock(&khd->lock);						\
+	return seq_list_start(&khd->rqs[domain], *pos);			\
+}									\
+									\
+static void *kyber_##name##_rqs_next(struct seq_file *m, void *v,	\
+				     loff_t *pos)			\
+{									\
+	struct blk_mq_hw_ctx *hctx = m->private;			\
+	struct kyber_hctx_data *khd = hctx->sched_data;			\
+									\
+	return seq_list_next(v, &khd->rqs[domain], pos);		\
+}									\
+									\
+static void kyber_##name##_rqs_stop(struct seq_file *m, void *v)	\
+	__releases(&khd->lock)						\
+{									\
+	struct blk_mq_hw_ctx *hctx = m->private;			\
+	struct kyber_hctx_data *khd = hctx->sched_data;			\
+									\
+	spin_unlock(&khd->lock);					\
+}									\
+									\
+static const struct seq_operations kyber_##name##_rqs_seq_ops = {	\
+	.start	= kyber_##name##_rqs_start,				\
+	.next	= kyber_##name##_rqs_next,				\
+	.stop	= kyber_##name##_rqs_stop,				\
+	.show	= blk_mq_debugfs_rq_show,				\
+};									\
+									\
+static int kyber_##name##_waiting_show(void *data, struct seq_file *m)	\
+{									\
+	struct blk_mq_hw_ctx *hctx = data;				\
+	struct kyber_hctx_data *khd = hctx->sched_data;			\
+	wait_queue_t *wait = &khd->domain_wait[domain];			\
+									\
+	seq_printf(m, "%d\n", !list_empty_careful(&wait->task_list));	\
+	return 0;							\
+}
+KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_READ, read)
+KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_SYNC_WRITE, sync_write)
+KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_OTHER, other)
+#undef KYBER_DEBUGFS_DOMAIN_ATTRS
+
+static int kyber_async_depth_show(void *data, struct seq_file *m)
+{
+	struct request_queue *q = data;
+	struct kyber_queue_data *kqd = q->elevator->elevator_data;
+
+	seq_printf(m, "%u\n", kqd->async_depth);
+	return 0;
+}
+
+static int kyber_cur_domain_show(void *data, struct seq_file *m)
+{
+	struct blk_mq_hw_ctx *hctx = data;
+	struct kyber_hctx_data *khd = hctx->sched_data;
+
+	switch (khd->cur_domain) {
+	case KYBER_READ:
+		seq_puts(m, "READ\n");
+		break;
+	case KYBER_SYNC_WRITE:
+		seq_puts(m, "SYNC_WRITE\n");
+		break;
+	case KYBER_OTHER:
+		seq_puts(m, "OTHER\n");
+		break;
+	default:
+		seq_printf(m, "%u\n", khd->cur_domain);
+		break;
+	}
+	return 0;
+}
+
+static int kyber_batching_show(void *data, struct seq_file *m)
+{
+	struct blk_mq_hw_ctx *hctx = data;
+	struct kyber_hctx_data *khd = hctx->sched_data;
+
+	seq_printf(m, "%u\n", khd->batching);
+	return 0;
+}
+
+#define KYBER_QUEUE_DOMAIN_ATTRS(name)	\
+	{#name "_tokens", 0400, kyber_##name##_tokens_show}
+static const struct blk_mq_debugfs_attr kyber_queue_debugfs_attrs[] = {
+	KYBER_QUEUE_DOMAIN_ATTRS(read),
+	KYBER_QUEUE_DOMAIN_ATTRS(sync_write),
+	KYBER_QUEUE_DOMAIN_ATTRS(other),
+	{"async_depth", 0400, kyber_async_depth_show},
+	{},
+};
+#undef KYBER_QUEUE_DOMAIN_ATTRS
+
+#define KYBER_HCTX_DOMAIN_ATTRS(name)					\
+	{#name "_rqs", 0400, .seq_ops = &kyber_##name##_rqs_seq_ops},	\
+	{#name "_waiting", 0400, kyber_##name##_waiting_show}
+static const struct blk_mq_debugfs_attr kyber_hctx_debugfs_attrs[] = {
+	KYBER_HCTX_DOMAIN_ATTRS(read),
+	KYBER_HCTX_DOMAIN_ATTRS(sync_write),
+	KYBER_HCTX_DOMAIN_ATTRS(other),
+	{"cur_domain", 0400, kyber_cur_domain_show},
+	{"batching", 0400, kyber_batching_show},
+	{},
+};
+#undef KYBER_HCTX_DOMAIN_ATTRS
+#endif
+
 static struct elevator_type kyber_sched = {
 	.ops.mq = {
 		.init_sched = kyber_init_sched,
@@ -696,6 +822,10 @@ static struct elevator_type kyber_sched = {
 		.has_work = kyber_has_work,
 	},
 	.uses_mq = true,
+#ifdef CONFIG_BLK_DEBUG_FS
+	.queue_debugfs_attrs = kyber_queue_debugfs_attrs,
+	.hctx_debugfs_attrs = kyber_hctx_debugfs_attrs,
+#endif
 	.elevator_attrs = kyber_sched_attrs,
 	.elevator_name = "kyber",
 	.elevator_owner = THIS_MODULE,
-- 
2.12.2

[PATCH v2 12/12] mq-deadline: add debugfs attributes

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Expose the fifo lists, cached next requests, batching state, and
dispatch list. It'd also be possible to add the sorted lists, but there
aren't already seq_file helpers for rbtrees.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 block/blk-mq-debugfs.c |   9 +++-
 block/blk-mq-debugfs.h |   1 +
 block/mq-deadline.c    | 123 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 131 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 8ec738f872e5..803aed4d7221 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -267,9 +267,8 @@ static const char *const rqf_name[] = {
 };
 #undef RQF_NAME
 
-int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
+int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq)
 {
-	struct request *rq = list_entry_rq(v);
 	const struct blk_mq_ops *const mq_ops = rq->q->mq_ops;
 	const unsigned int op = rq->cmd_flags & REQ_OP_MASK;
 
@@ -291,6 +290,12 @@ int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
 	seq_puts(m, "}\n");
 	return 0;
 }
+EXPORT_SYMBOL_GPL(__blk_mq_debugfs_rq_show);
+
+int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
+{
+	return __blk_mq_debugfs_rq_show(m, list_entry_rq(v));
+}
 EXPORT_SYMBOL_GPL(blk_mq_debugfs_rq_show);
 
 static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index 7c67f813a294..b72e5c5f065e 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -11,6 +11,7 @@ struct blk_mq_debugfs_attr {
 	const struct seq_operations *seq_ops;
 };
 
+int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq);
 int blk_mq_debugfs_rq_show(struct seq_file *m, void *v);
 
 int blk_mq_debugfs_register(struct request_queue *q);
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 236121633ca0..1b964a387afe 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -19,6 +19,7 @@
 
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-tag.h"
 #include "blk-mq-sched.h"
 
@@ -517,6 +518,125 @@ static struct elv_fs_entry deadline_attrs[] = {
 	__ATTR_NULL
 };
 
+#ifdef CONFIG_BLK_DEBUG_FS
+#define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name)				\
+static void *deadline_##name##_fifo_start(struct seq_file *m,		\
+					  loff_t *pos)			\
+	__acquires(&dd->lock)						\
+{									\
+	struct request_queue *q = m->private;				\
+	struct deadline_data *dd = q->elevator->elevator_data;		\
+									\
+	spin_lock(&dd->lock);						\
+	return seq_list_start(&dd->fifo_list[ddir], *pos);		\
+}									\
+									\
+static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,	\
+					 loff_t *pos)			\
+{									\
+	struct request_queue *q = m->private;				\
+	struct deadline_data *dd = q->elevator->elevator_data;		\
+									\
+	return seq_list_next(v, &dd->fifo_list[ddir], pos);		\
+}									\
+									\
+static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)	\
+	__releases(&dd->lock)						\
+{									\
+	struct request_queue *q = m->private;				\
+	struct deadline_data *dd = q->elevator->elevator_data;		\
+									\
+	spin_unlock(&dd->lock);						\
+}									\
+									\
+static const struct seq_operations deadline_##name##_fifo_seq_ops = {	\
+	.start	= deadline_##name##_fifo_start,				\
+	.next	= deadline_##name##_fifo_next,				\
+	.stop	= deadline_##name##_fifo_stop,				\
+	.show	= blk_mq_debugfs_rq_show,				\
+};									\
+									\
+static int deadline_##name##_next_rq_show(void *data,			\
+					  struct seq_file *m)		\
+{									\
+	struct request_queue *q = data;					\
+	struct deadline_data *dd = q->elevator->elevator_data;		\
+	struct request *rq = dd->next_rq[ddir];				\
+									\
+	if (rq)								\
+		__blk_mq_debugfs_rq_show(m, rq);			\
+	return 0;							\
+}
+DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
+DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
+#undef DEADLINE_DEBUGFS_DDIR_ATTRS
+
+static int deadline_batching_show(void *data, struct seq_file *m)
+{
+	struct request_queue *q = data;
+	struct deadline_data *dd = q->elevator->elevator_data;
+
+	seq_printf(m, "%u\n", dd->batching);
+	return 0;
+}
+
+static int deadline_starved_show(void *data, struct seq_file *m)
+{
+	struct request_queue *q = data;
+	struct deadline_data *dd = q->elevator->elevator_data;
+
+	seq_printf(m, "%u\n", dd->starved);
+	return 0;
+}
+
+static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
+	__acquires(&dd->lock)
+{
+	struct request_queue *q = m->private;
+	struct deadline_data *dd = q->elevator->elevator_data;
+
+	spin_lock(&dd->lock);
+	return seq_list_start(&dd->dispatch, *pos);
+}
+
+static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct request_queue *q = m->private;
+	struct deadline_data *dd = q->elevator->elevator_data;
+
+	return seq_list_next(v, &dd->dispatch, pos);
+}
+
+static void deadline_dispatch_stop(struct seq_file *m, void *v)
+	__releases(&dd->lock)
+{
+	struct request_queue *q = m->private;
+	struct deadline_data *dd = q->elevator->elevator_data;
+
+	spin_unlock(&dd->lock);
+}
+
+static const struct seq_operations deadline_dispatch_seq_ops = {
+	.start	= deadline_dispatch_start,
+	.next	= deadline_dispatch_next,
+	.stop	= deadline_dispatch_stop,
+	.show	= blk_mq_debugfs_rq_show,
+};
+
+#define DEADLINE_QUEUE_DDIR_ATTRS(name)						\
+	{#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops},	\
+	{#name "_next_rq", 0400, deadline_##name##_next_rq_show}
+static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
+	DEADLINE_QUEUE_DDIR_ATTRS(read),
+	DEADLINE_QUEUE_DDIR_ATTRS(write),
+	{"batching", 0400, deadline_batching_show},
+	{"starved", 0400, deadline_starved_show},
+	{"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
+	{},
+};
+#undef DEADLINE_QUEUE_DDIR_ATTRS
+#endif
+
 static struct elevator_type mq_deadline = {
 	.ops.mq = {
 		.insert_requests	= dd_insert_requests,
@@ -533,6 +653,9 @@ static struct elevator_type mq_deadline = {
 	},
 
 	.uses_mq	= true,
+#ifdef CONFIG_BLK_DEBUG_FS
+	.queue_debugfs_attrs = deadline_queue_debugfs_attrs,
+#endif
 	.elevator_attrs = deadline_attrs,
 	.elevator_name = "mq-deadline",
 	.elevator_owner = THIS_MODULE,
-- 
2.12.2

Re: [PATCH v2 01/12] blk-mq-debugfs: separate flags with |

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> This reads more naturally than spaces.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 02/12] blk-mq-debugfs: clean up flag definitions

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Make sure the spelled out flag names match the definition. This also
> adds a missing hctx state, BLK_MQ_S_START_ON_RUN, and a missing
> cmd_flag, __REQ_NOUNMAP.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c | 201 ++++++++++++++++++++++++++-----------------------
>  1 file changed, 108 insertions(+), 93 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 03/12] blk-mq-debugfs: error on long write to queue "state" file

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> blk_queue_flags_store() currently truncates and returns a short write if
> the operation being written is too long. This can give us weird results,
> like here:
> 
> $ echo "run            bar"
> echo: write error: invalid argument
> $ dmesg
> [ 1103.075435] blk_queue_flags_store: unsupported operation bar. Use either 'run' or 'start'
> 
> Instead, return an error if the user does this. While we're here, make
> the argument names consistent with everywhere else in this file.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 04/12] blk-mq-debugfs: don't open code strstrip()

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Slightly more readable, plus we also strip leading spaces.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 05/12] blk-mq-debugfs: rename hw queue directories from <n> to hctx<n>

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> It's not clear what these numbered directories represent unless you
> consult the code. We're about to get rid of the intermediate "mq"
> directory, so these would be even more confusing without that context.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> index 109ae9f3d400..2eae3238fb35 100644
> --- a/block/blk-mq-debugfs.c
> +++ b/block/blk-mq-debugfs.c
> @@ -936,7 +936,7 @@ static int blk_mq_debugfs_register_hctx(struct request_queue *q,
>  	char name[20];
>  	int i;
>  
> -	snprintf(name, sizeof(name), "%u", hctx->queue_num);
> +	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);
>  	hctx_dir = debugfs_create_dir(name, q->mq_debugfs_dir);
>  	if (!hctx_dir)
>  		return -ENOMEM;
> 
Hmm. The number actually corresponds to /sys/block/XX/mq/<num>
With this patch we would break this mapping, no?

I'd rather keep it in sync with /sys/block ...

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 06/12] blk-mq-debugfs: get rid of a bunch of boilerplate

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> A large part of blk-mq-debugfs.c is file_operations and seq_file
> boilerplate. This sucks as is but will suck even more when schedulers
> can define their own debugfs entries. Factor it all out into a single
> blk_mq_debugfs_fops which multiplexes as needed. We store the
> request_queue, blk_mq_hw_ctx, or blk_mq_ctx in the parent directory
> dentry, which is kind of hacky, but it works.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c | 464 +++++++++++++++----------------------------------
>  1 file changed, 136 insertions(+), 328 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 07/12] blk-mq: Do not invoke queue operations on a dead queue

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Bart Van Assche <bart.vanassche@sandisk.com>
> 
> In commit e869b5462f83 ("blk-mq: Unregister debugfs attributes
> earlier"), we shuffled the debugfs cleanup around so that the "state"
> attribute was removed before we freed the blk-mq data structures.
> However, later changes are going to undo that, so we need to explicitly
> disallow running a dead queue.
> 
> [Omar: rebased and updated commit message]
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> ---
>  block/blk-mq-debugfs.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 08/12] blk-mq: move debugfs declarations to a separate header file

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Preparation for adding more declarations.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-core.c       |  1 +
>  block/blk-mq-debugfs.c |  1 +
>  block/blk-mq-debugfs.h | 29 +++++++++++++++++++++++++++++
>  block/blk-mq-sysfs.c   |  1 +
>  block/blk-mq.h         | 28 ----------------------------
>  block/blk-sysfs.c      |  1 +
>  6 files changed, 33 insertions(+), 28 deletions(-)
>  create mode 100644 block/blk-mq-debugfs.h
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 09/12] blk-mq: untangle debugfs and sysfs

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Originally, I tied debugfs registration/unregistration together with
> sysfs. There's no reason to do this, and it's getting in the way of
> letting schedulers define their own debugfs attributes. Instead, tie the
> debugfs registration to the lifetime of the structures themselves.
> 
> The saner lifetimes mean we can also get rid of the extra mq directory
> and move everything one level up. I.e., nvme0n1/mq/hctx0/tags is now
> just nvme0n1/hctx0/tags.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-core.c       |   9 +---
>  block/blk-mq-debugfs.c | 110 ++++++++++++++++++++++++++++---------------------
>  block/blk-mq-debugfs.h |  21 ++++++++--
>  block/blk-mq-sysfs.c   |  11 -----
>  block/blk-mq.c         |   7 ++++
>  block/blk-sysfs.c      |   2 +
>  include/linux/blk-mq.h |   4 ++
>  include/linux/blkdev.h |   1 -
>  8 files changed, 94 insertions(+), 71 deletions(-)
> 
Again, I really liked the symmetry between sysfs and debugfs mq entries.
This will definitely break it.

Not sure if that's a real issue, but personally I liked the mapping.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 10/12] blk-mq-debugfs: allow schedulers to register debugfs attributes

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> This provides the infrastructure for schedulers to expose their internal
> state through debugfs. We add a list of queue attributes and a list of
> hctx attributes to struct elevator_type and wire them up when switching
> schedulers.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c   | 74 ++++++++++++++++++++++++++++++++++++++++++------
>  block/blk-mq-debugfs.h   | 34 ++++++++++++++++++++++
>  block/blk-mq-sched.c     | 24 ++++++++++------
>  include/linux/blk-mq.h   |  1 +
>  include/linux/blkdev.h   |  1 +
>  include/linux/elevator.h |  7 +++++
>  6 files changed, 124 insertions(+), 17 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 11/12] kyber: add debugfs attributes

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Expose the domain token pools, asynchronous sbitmap depth, domain
> request lists, and batching state.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c |   3 +-
>  block/blk-mq-debugfs.h |   2 +
>  block/kyber-iosched.c  | 130 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 134 insertions(+), 1 deletion(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 12/12] mq-deadline: add debugfs attributes

[Hannes Reinecke]

On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Expose the fifo lists, cached next requests, batching state, and
> dispatch list. It'd also be possible to add the sorted lists, but there
> aren't already seq_file helpers for rbtrees.
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c |   9 +++-
>  block/blk-mq-debugfs.h |   1 +
>  block/mq-deadline.c    | 123 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 131 insertions(+), 2 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)

Re: [PATCH v2 05/12] blk-mq-debugfs: rename hw queue directories from <n> to hctx<n>

[Jens Axboe]

On Thu, May 04 2017, Hannes Reinecke wrote:
> On 05/04/2017 09:31 AM, Omar Sandoval wrote:
> > From: Omar Sandoval <osandov@fb.com>
> > 
> > It's not clear what these numbered directories represent unless you
> > consult the code. We're about to get rid of the intermediate "mq"
> > directory, so these would be even more confusing without that context.
> > 
> > Signed-off-by: Omar Sandoval <osandov@fb.com>
> > ---
> >  block/blk-mq-debugfs.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> > index 109ae9f3d400..2eae3238fb35 100644
> > --- a/block/blk-mq-debugfs.c
> > +++ b/block/blk-mq-debugfs.c
> > @@ -936,7 +936,7 @@ static int blk_mq_debugfs_register_hctx(struct request_queue *q,
> >  	char name[20];
> >  	int i;
> >  
> > -	snprintf(name, sizeof(name), "%u", hctx->queue_num);
> > +	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);
> >  	hctx_dir = debugfs_create_dir(name, q->mq_debugfs_dir);
> >  	if (!hctx_dir)
> >  		return -ENOMEM;
> > 
> Hmm. The number actually corresponds to /sys/block/XX/mq/<num>
> With this patch we would break this mapping, no?
> 
> I'd rather keep it in sync with /sys/block ...

It's still the same number, it's just clearer what it is. I like this
change.

-- 
Jens Axboe

Re: [PATCH v2 10/12] blk-mq-debugfs: allow schedulers to register debugfs attributes

[Jens Axboe]

On Thu, May 04 2017, Omar Sandoval wrote:
> diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
> index 596e9b16d3d1..29ecb43aa412 100644
> --- a/block/blk-mq-debugfs.h
> +++ b/block/blk-mq-debugfs.h
> @@ -2,6 +2,15 @@
>  #define INT_BLK_MQ_DEBUGFS_H
>  
>  #ifdef CONFIG_BLK_DEBUG_FS
> +struct blk_mq_debugfs_attr {
> +	const char *name;
> +	umode_t mode;
> +	int (*show)(void *, struct seq_file *);
> +	ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
> +	/* Set either .show or .seq_ops. */
> +	const struct seq_operations *seq_ops;
> +};
> +
>  int blk_mq_debugfs_register(struct request_queue *q);
>  void blk_mq_debugfs_unregister(struct request_queue *q);
>  int blk_mq_debugfs_register_hctx(struct request_queue *q,

This needs a <linux/seq_file.h> include in blk-mq-debugfs.h, or my
compile starts breaking on both kyber and mq-deadline.

-- 
Jens Axboe

Re: [PATCH v2 03/12] blk-mq-debugfs: error on long write to queue "state" file

[Bart Van Assche]

On Thu, 2017-05-04 at 00:31 -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>=20
> blk_queue_flags_store() currently truncates and returns a short write if
> the operation being written is too long. This can give us weird results,
> like here:
>=20
> $ echo "run            bar"
> echo: write error: invalid argument
> $ dmesg
> [ 1103.075435] blk_queue_flags_store: unsupported operation bar. Use eith=
er 'run' or 'start'
>=20
> Instead, return an error if the user does this. While we're here, make
> the argument names consistent with everywhere else in this file.

Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>=

Re: [PATCH v2 04/12] blk-mq-debugfs: don't open code strstrip()

[Bart Van Assche]

On Thu, 2017-05-04 at 00:31 -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>=20
> Slightly more readable, plus we also strip leading spaces.
>=20
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>  block/blk-mq-debugfs.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>=20
> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> index 2a19237455d4..109ae9f3d400 100644
> --- a/block/blk-mq-debugfs.c
> +++ b/block/blk-mq-debugfs.c
> @@ -111,17 +111,16 @@ static ssize_t blk_queue_flags_store(struct file *f=
ile, const char __user *buf,
>  				     size_t count, loff_t *ppos)
>  {
>  	struct request_queue *q =3D file_inode(file)->i_private;
> -	char op[16] =3D { }, *s;
> +	char opbuf[16] =3D { }, *op;
> =20
> -	if (count >=3D sizeof(op)) {
> +	if (count >=3D sizeof(opbuf)) {
>  		pr_err("%s: operation too long\n", __func__);
>  		goto inval;
>  	}
> =20
> -	if (copy_from_user(op, buf, count))
> +	if (copy_from_user(opbuf, buf, count))
>  		return -EFAULT;
> -	s =3D op;
> -	strsep(&s, " \t\n"); /* strip trailing whitespace */
> +	op =3D strstrip(opbuf);
>  	if (strcmp(op, "run") =3D=3D 0) {
>  		blk_mq_run_hw_queues(q, true);
>  	} else if (strcmp(op, "start") =3D=3D 0) {

Hello Omar,

Sorry but in my opinion the value of this patch is so small that I'm not su=
re
it's worth to merge this patch.

Bart.=

Re: [PATCH v2 06/12] blk-mq-debugfs: get rid of a bunch of boilerplate

[Bart Van Assche]

On Thu, 2017-05-04 at 00:31 -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>=20
> A large part of blk-mq-debugfs.c is file_operations and seq_file
> boilerplate. This sucks as is but will suck even more when schedulers
> can define their own debugfs entries. Factor it all out into a single
> blk_mq_debugfs_fops which multiplexes as needed. We store the
> request_queue, blk_mq_hw_ctx, or blk_mq_ctx in the parent directory
> dentry, which is kind of hacky, but it works.

Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>=

Re: [PATCH v2 11/12] kyber: add debugfs attributes

[Bart Van Assche]

On Thu, 2017-05-04 at 00:31 -0700, Omar Sandoval wrote:
> +#define KYBER_DEBUGFS_DOMAIN_ATTRS(domain, name)

Hello Omar,

That's a really long macro name. Have you considered to leave out "_DOMAIN"
from the name of this and related macros?

Bart.=