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Commit 91d68905 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

blk-mq: Export queue state through /sys/kernel/debug/block/*/state 



Make it possible to check whether or not a block layer queue has
been stopped. Make it possible to start and to run a blk-mq queue
from user space.

Signed-off-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent bcd069bb

block/blk-mq-debugfs.c

+106 −0
Original line number Diff line number Diff line
@@ -43,6 +43,109 @@ static int blk_mq_debugfs_seq_open(struct inode *inode, struct file *file, 
	return ret;

}



static int blk_flags_show(struct seq_file *m, const unsigned long flags,

			  const char *const *flag_name, int flag_name_count)

{

	bool sep = false;

	int i;



	for (i = 0; i < sizeof(flags) * BITS_PER_BYTE; i++) {

		if (!(flags & BIT(i)))

			continue;

		if (sep)

			seq_puts(m, " ");

		sep = true;

		if (i < flag_name_count && flag_name[i])

			seq_puts(m, flag_name[i]);

		else

			seq_printf(m, "%d", i);

	}

	seq_puts(m, "\n");

	return 0;

}



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",

};



static int blk_queue_flags_show(struct seq_file *m, void *v)

{

	struct request_queue *q = m->private;



	blk_flags_show(m, q->queue_flags, blk_queue_flag_name,

		       ARRAY_SIZE(blk_queue_flag_name));

	return 0;

}



static ssize_t blk_queue_flags_store(struct file *file, const char __user *ubuf,

				     size_t len, loff_t *offp)

{

	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))

		return -EFAULT;

	s = op;

	strsep(&s, " \t\n"); /* strip trailing whitespace */

	if (strcmp(op, "run") == 0) {

		blk_mq_run_hw_queues(q, true);

	} 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);

		return -EINVAL;

	}

	return len;

}



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 const struct blk_mq_debugfs_attr blk_queue_attrs[] = {

	{"state", 0600, &blk_queue_flags_fops},

	{},

};



static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)

{

	if (stat->nr_samples) {
@@ -735,6 +838,9 @@ int blk_mq_debugfs_register_hctxs(struct request_queue *q) 
	if (!q->debugfs_dir)

		return -ENOENT;



	if (!debugfs_create_files(q->debugfs_dir, q, blk_queue_attrs))

		goto err;



	q->mq_debugfs_dir = debugfs_create_dir("mq", q->debugfs_dir);

	if (!q->mq_debugfs_dir)

		goto err;