Commit 09341997 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

blktrace: print human-readable act_mask 



Impact: new feature, allow symbolic values in /debug/tracing/act_mask

Print stringified act_mask instead of hex value:

 # cat act_mask
 read,write,barrier,sync,queue,requeue,issue,complete,fs,pc,ahead,meta,
 discard,drv_data
 # echo "meta,write" > act_mask
 # cat act_mask
 write,meta

Also:
 - make act_mask accept "ahead", "meta", "discard" and "drv_data"
 - use strsep() instead of strchr() to parse user input
 - return -EINVAL if a token is not found in the mask map
 - fix a bug that 'value' is unsigned, so it can < 0
 - propagate error value of blk_trace_mask2str() to userspace, but not
   always return -ENXIO.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Acked-by: default avatarJens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49C8AB42.1000802@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e0dc81be

kernel/trace/blktrace.c

+65 −38
Original line number Diff line number Diff line
@@ -1316,53 +1316,77 @@ struct attribute_group blk_trace_attr_group = { 
	.attrs = blk_trace_attrs,

};



static int blk_str2act_mask(const char *str)

static const struct {

	int mask;

	const char *str;

} mask_maps[] = {

	{ BLK_TC_READ,		"read"		},

	{ BLK_TC_WRITE,		"write"		},

	{ BLK_TC_BARRIER,	"barrier"	},

	{ BLK_TC_SYNC,		"sync"		},

	{ BLK_TC_QUEUE,		"queue"		},

	{ BLK_TC_REQUEUE,	"requeue"	},

	{ BLK_TC_ISSUE,		"issue"		},

	{ BLK_TC_COMPLETE,	"complete"	},

	{ BLK_TC_FS,		"fs"		},

	{ BLK_TC_PC,		"pc"		},

	{ BLK_TC_AHEAD,		"ahead"		},

	{ BLK_TC_META,		"meta"		},

	{ BLK_TC_DISCARD,	"discard"	},

	{ BLK_TC_DRV_DATA,	"drv_data"	},

};



static int blk_trace_str2mask(const char *str)

{

	int i;

	int mask = 0;

	char *copy = kstrdup(str, GFP_KERNEL), *s;

	char *s, *token;



	if (copy == NULL)

	s = kstrdup(str, GFP_KERNEL);

	if (s == NULL)

		return -ENOMEM;



	s = strstrip(copy);

	s = strstrip(s);



	while (1) {

		char *sep = strchr(s, ',');



		if (sep != NULL)

			*sep = '\0';



		if (strcasecmp(s, "barrier") == 0)

			mask |= BLK_TC_BARRIER;

		else if (strcasecmp(s, "complete") == 0)

			mask |= BLK_TC_COMPLETE;

		else if (strcasecmp(s, "fs") == 0)

			mask |= BLK_TC_FS;

		else if (strcasecmp(s, "issue") == 0)

			mask |= BLK_TC_ISSUE;

		else if (strcasecmp(s, "pc") == 0)

			mask |= BLK_TC_PC;

		else if (strcasecmp(s, "queue") == 0)

			mask |= BLK_TC_QUEUE;

		else if (strcasecmp(s, "read") == 0)

			mask |= BLK_TC_READ;

		else if (strcasecmp(s, "requeue") == 0)

			mask |= BLK_TC_REQUEUE;

		else if (strcasecmp(s, "sync") == 0)

			mask |= BLK_TC_SYNC;

		else if (strcasecmp(s, "write") == 0)

			mask |= BLK_TC_WRITE;



		if (sep == NULL)

		token = strsep(&s, ",");

		if (token == NULL)

			break;



		s = sep + 1;

		if (*token == '\0')

			continue;



		for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {

			if (strcasecmp(token, mask_maps[i].str) == 0) {

				mask |= mask_maps[i].mask;

				break;

			}

		}

		if (i == ARRAY_SIZE(mask_maps)) {

			mask = -EINVAL;

			break;

		}

	}

	kfree(copy);

	kfree(s);



	return mask;

}



static ssize_t blk_trace_mask2str(char *buf, int mask)

{

	int i;

	char *p = buf;



	for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {

		if (mask & mask_maps[i].mask) {

			p += sprintf(p, "%s%s",

				    (p == buf) ? "" : ",", mask_maps[i].str);

		}

	}

	*p++ = '\n';



	return p - buf;

}



static struct request_queue *blk_trace_get_queue(struct block_device *bdev)

{

	if (bdev->bd_disk == NULL)
@@ -1399,7 +1423,7 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev, 
	if (q->blk_trace == NULL)

		ret = sprintf(buf, "disabled\n");

	else if (attr == &dev_attr_act_mask)

		ret = sprintf(buf, "%#x\n", q->blk_trace->act_mask);

		ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);

	else if (attr == &dev_attr_pid)

		ret = sprintf(buf, "%u\n", q->blk_trace->pid);

	else if (attr == &dev_attr_start_lba)
@@ -1424,7 +1448,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev, 
	struct request_queue *q;

	struct hd_struct *p;

	u64 value;

	ssize_t ret = -ENXIO;

	ssize_t ret = -EINVAL;



	if (count == 0)

		goto out;
@@ -1432,13 +1456,16 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev, 
	if (attr == &dev_attr_act_mask) {

		if (sscanf(buf, "%llx", &value) != 1) {

			/* Assume it is a list of trace category names */

			value = blk_str2act_mask(buf);

			if (value < 0)

			ret = blk_trace_str2mask(buf);

			if (ret < 0)

				goto out;

			value = ret;

		}

	} else if (sscanf(buf, "%llu", &value) != 1)

		goto out;



	ret = -ENXIO;



	lock_kernel();

	p = dev_to_part(dev);

	bdev = bdget(part_devt(p));

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