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blktrace: support per-partition tracing
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Though one can specify '-d /dev/sda1' when using blktrace, it still
traces the whole sda.

To support per-partition tracing, when we start tracing, we initialize
bt->start_lba and bt->end_lba to the start and end sector of that
partition.

Note some actions are per device, thus we don't filter 0-sector events.

The original patch and discussion can be found here:
	http://marc.info/?l=linux-btrace&m=122949374214540&w=2

Signed-off-by: Shawn Du <[email protected]>
Signed-off-by: Li Zefan <[email protected]>
Acked-by: "Theodore Ts'o" <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jens Axboe <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
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duyuyang-git authored and Ingo Molnar committed Apr 16, 2009
1 parent 9cfe06f commit d0deef5
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Showing 4 changed files with 36 additions and 20 deletions.
2 changes: 1 addition & 1 deletion block/compat_ioctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -568,7 +568,7 @@ static int compat_blk_trace_setup(struct block_device *bdev, char __user *arg)
memcpy(&buts.name, &cbuts.name, 32);

mutex_lock(&bdev->bd_mutex);
ret = do_blk_trace_setup(q, b, bdev->bd_dev, &buts);
ret = do_blk_trace_setup(q, b, bdev->bd_dev, bdev, &buts);
mutex_unlock(&bdev->bd_mutex);
if (ret)
return ret;
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1 change: 1 addition & 0 deletions drivers/scsi/sg.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1065,6 +1065,7 @@ sg_ioctl(struct inode *inode, struct file *filp,
return blk_trace_setup(sdp->device->request_queue,
sdp->disk->disk_name,
MKDEV(SCSI_GENERIC_MAJOR, sdp->index),
NULL,
(char *)arg);
case BLKTRACESTART:
return blk_trace_startstop(sdp->device->request_queue, 1);
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24 changes: 13 additions & 11 deletions include/linux/blktrace_api.h
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Original file line number Diff line number Diff line change
Expand Up @@ -165,8 +165,9 @@ struct blk_trace {

extern int blk_trace_ioctl(struct block_device *, unsigned, char __user *);
extern void blk_trace_shutdown(struct request_queue *);
extern int do_blk_trace_setup(struct request_queue *q,
char *name, dev_t dev, struct blk_user_trace_setup *buts);
extern int do_blk_trace_setup(struct request_queue *q, char *name,
dev_t dev, struct block_device *bdev,
struct blk_user_trace_setup *buts);
extern void __trace_note_message(struct blk_trace *, const char *fmt, ...);

/**
Expand All @@ -193,22 +194,23 @@ extern void __trace_note_message(struct blk_trace *, const char *fmt, ...);
extern void blk_add_driver_data(struct request_queue *q, struct request *rq,
void *data, size_t len);
extern int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
struct block_device *bdev,
char __user *arg);
extern int blk_trace_startstop(struct request_queue *q, int start);
extern int blk_trace_remove(struct request_queue *q);

extern struct attribute_group blk_trace_attr_group;

#else /* !CONFIG_BLK_DEV_IO_TRACE */
#define blk_trace_ioctl(bdev, cmd, arg) (-ENOTTY)
#define blk_trace_shutdown(q) do { } while (0)
#define do_blk_trace_setup(q, name, dev, buts) (-ENOTTY)
#define blk_add_driver_data(q, rq, data, len) do {} while (0)
#define blk_trace_setup(q, name, dev, arg) (-ENOTTY)
#define blk_trace_startstop(q, start) (-ENOTTY)
#define blk_trace_remove(q) (-ENOTTY)
#define blk_add_trace_msg(q, fmt, ...) do { } while (0)

# define blk_trace_ioctl(bdev, cmd, arg) (-ENOTTY)
# define blk_trace_shutdown(q) do { } while (0)
# define do_blk_trace_setup(q, name, dev, bdev, buts) (-ENOTTY)
# define blk_add_driver_data(q, rq, data, len) do {} while (0)
# define blk_trace_setup(q, name, dev, bdev, arg) (-ENOTTY)
# define blk_trace_startstop(q, start) (-ENOTTY)
# define blk_trace_remove(q) (-ENOTTY)
# define blk_add_trace_msg(q, fmt, ...) do { } while (0)
#endif /* CONFIG_BLK_DEV_IO_TRACE */

#endif /* __KERNEL__ */
#endif
29 changes: 21 additions & 8 deletions kernel/trace/blktrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -147,7 +147,7 @@ static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
{
if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
return 1;
if (sector < bt->start_lba || sector > bt->end_lba)
if (sector && (sector < bt->start_lba || sector > bt->end_lba))
return 1;
if (bt->pid && pid != bt->pid)
return 1;
Expand Down Expand Up @@ -192,7 +192,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
what |= MASK_TC_BIT(rw, DISCARD);

pid = tsk->pid;
if (unlikely(act_log_check(bt, what, sector, pid)))
if (act_log_check(bt, what, sector, pid))
return;
cpu = raw_smp_processor_id();

Expand Down Expand Up @@ -407,11 +407,13 @@ static struct rchan_callbacks blk_relay_callbacks = {
* Setup everything required to start tracing
*/
int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
struct blk_user_trace_setup *buts)
struct block_device *bdev,
struct blk_user_trace_setup *buts)
{
struct blk_trace *old_bt, *bt = NULL;
struct dentry *dir = NULL;
int ret, i;
struct hd_struct *part = NULL;

if (!buts->buf_size || !buts->buf_nr)
return -EINVAL;
Expand Down Expand Up @@ -480,11 +482,21 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (!bt->act_mask)
bt->act_mask = (u16) -1;

bt->start_lba = buts->start_lba;
bt->end_lba = buts->end_lba;
if (!bt->end_lba)
if (bdev)
part = bdev->bd_part;

if (part) {
bt->start_lba = part->start_sect;
bt->end_lba = part->start_sect + part->nr_sects;
} else
bt->end_lba = -1ULL;

/* overwrite with user settings */
if (buts->start_lba)
bt->start_lba = buts->start_lba;
if (buts->end_lba)
bt->end_lba = buts->end_lba;

bt->pid = buts->pid;
bt->trace_state = Blktrace_setup;

Expand All @@ -505,6 +517,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
}

int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
struct block_device *bdev,
char __user *arg)
{
struct blk_user_trace_setup buts;
Expand All @@ -514,7 +527,7 @@ int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (ret)
return -EFAULT;

ret = do_blk_trace_setup(q, name, dev, &buts);
ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
if (ret)
return ret;

Expand Down Expand Up @@ -582,7 +595,7 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
switch (cmd) {
case BLKTRACESETUP:
bdevname(bdev, b);
ret = blk_trace_setup(q, b, bdev->bd_dev, arg);
ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
break;
case BLKTRACESTART:
start = 1;
Expand Down

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