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

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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: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Bart Van Assche 2017-04-10 16:13:15 -06:00 committed by Jens Axboe
parent bcd069bb25
commit 91d68905ae
1 changed files with 106 additions and 0 deletions
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106
block/blk-mq-debugfs.c
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@ -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;