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blktrace: Add blktrace ioctls to SCSI generic devices
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Since the SCSI layer uses the request queues from the block layer, blktrace can
also be used to trace the requests to all SCSI devices (like SCSI tape drives),
not only disks. The only missing part is the ioctl interface to start and stop
tracing.

This patch adds the SETUP, START, STOP and TEARDOWN ioctls from blktrace to the
sg device files. With this change, blktrace can be used for SCSI devices like
for disks, e.g.: blktrace -d /dev/sg1 -o - | blkparse -i -

Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Christof Schmitt authored and Jens Axboe committed Jan 28, 2008
1 parent 9152530 commit 6da127a
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Showing 4 changed files with 40 additions and 13 deletions.
24 changes: 14 additions & 10 deletions block/blktrace.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -235,7 +235,7 @@ static void blk_trace_cleanup(struct blk_trace *bt)
kfree(bt);
}

static int blk_trace_remove(struct request_queue *q)
int blk_trace_remove(struct request_queue *q)
{
struct blk_trace *bt;

Expand All @@ -249,6 +249,7 @@ static int blk_trace_remove(struct request_queue *q)

return 0;
}
EXPORT_SYMBOL_GPL(blk_trace_remove);

static int blk_dropped_open(struct inode *inode, struct file *filp)
{
Expand Down Expand Up @@ -316,18 +317,17 @@ static struct rchan_callbacks blk_relay_callbacks = {
/*
* Setup everything required to start tracing
*/
int do_blk_trace_setup(struct request_queue *q, struct block_device *bdev,
int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
struct blk_user_trace_setup *buts)
{
struct blk_trace *old_bt, *bt = NULL;
struct dentry *dir = NULL;
char b[BDEVNAME_SIZE];
int ret, i;

if (!buts->buf_size || !buts->buf_nr)
return -EINVAL;

strcpy(buts->name, bdevname(bdev, b));
strcpy(buts->name, name);

/*
* some device names have larger paths - convert the slashes
Expand All @@ -352,7 +352,7 @@ int do_blk_trace_setup(struct request_queue *q, struct block_device *bdev,
goto err;

bt->dir = dir;
bt->dev = bdev->bd_dev;
bt->dev = dev;
atomic_set(&bt->dropped, 0);

ret = -EIO;
Expand Down Expand Up @@ -399,8 +399,8 @@ int do_blk_trace_setup(struct request_queue *q, struct block_device *bdev,
return ret;
}

static int blk_trace_setup(struct request_queue *q, struct block_device *bdev,
char __user *arg)
int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
char __user *arg)
{
struct blk_user_trace_setup buts;
int ret;
Expand All @@ -409,7 +409,7 @@ static int blk_trace_setup(struct request_queue *q, struct block_device *bdev,
if (ret)
return -EFAULT;

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

Expand All @@ -418,8 +418,9 @@ static int blk_trace_setup(struct request_queue *q, struct block_device *bdev,

return 0;
}
EXPORT_SYMBOL_GPL(blk_trace_setup);

static int blk_trace_startstop(struct request_queue *q, int start)
int blk_trace_startstop(struct request_queue *q, int start)
{
struct blk_trace *bt;
int ret;
Expand Down Expand Up @@ -452,6 +453,7 @@ static int blk_trace_startstop(struct request_queue *q, int start)

return ret;
}
EXPORT_SYMBOL_GPL(blk_trace_startstop);

/**
* blk_trace_ioctl: - handle the ioctls associated with tracing
Expand All @@ -464,6 +466,7 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
{
struct request_queue *q;
int ret, start = 0;
char b[BDEVNAME_SIZE];

q = bdev_get_queue(bdev);
if (!q)
Expand All @@ -473,7 +476,8 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)

switch (cmd) {
case BLKTRACESETUP:
ret = blk_trace_setup(q, bdev, arg);
strcpy(b, bdevname(bdev, b));
ret = blk_trace_setup(q, b, bdev->bd_dev, arg);
break;
case BLKTRACESTART:
start = 1;
Expand Down
5 changes: 4 additions & 1 deletion block/compat_ioctl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -545,6 +545,7 @@ static int compat_blk_trace_setup(struct block_device *bdev, char __user *arg)
struct blk_user_trace_setup buts;
struct compat_blk_user_trace_setup cbuts;
struct request_queue *q;
char b[BDEVNAME_SIZE];
int ret;

q = bdev_get_queue(bdev);
Expand All @@ -554,6 +555,8 @@ static int compat_blk_trace_setup(struct block_device *bdev, char __user *arg)
if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
return -EFAULT;

strcpy(b, bdevname(bdev, b));

buts = (struct blk_user_trace_setup) {
.act_mask = cbuts.act_mask,
.buf_size = cbuts.buf_size,
Expand All @@ -565,7 +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, bdev, &buts);
ret = do_blk_trace_setup(q, b, bdev->bd_dev, &buts);
mutex_unlock(&bdev->bd_mutex);
if (ret)
return ret;
Expand Down
12 changes: 12 additions & 0 deletions drivers/scsi/sg.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@ static int sg_version_num = 30534; /* 2 digits for each component */
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/scatterlist.h>
#include <linux/blktrace_api.h>

#include "scsi.h"
#include <scsi/scsi_dbg.h>
Expand Down Expand Up @@ -1067,6 +1068,17 @@ sg_ioctl(struct inode *inode, struct file *filp,
case BLKSECTGET:
return put_user(sdp->device->request_queue->max_sectors * 512,
ip);
case BLKTRACESETUP:
return blk_trace_setup(sdp->device->request_queue,
sdp->disk->disk_name,
sdp->device->sdev_gendev.devt,
(char *)arg);
case BLKTRACESTART:
return blk_trace_startstop(sdp->device->request_queue, 1);
case BLKTRACESTOP:
return blk_trace_startstop(sdp->device->request_queue, 0);
case BLKTRACETEARDOWN:
return blk_trace_remove(sdp->device->request_queue);
default:
if (read_only)
return -EPERM; /* don't know so take safe approach */
Expand Down
12 changes: 10 additions & 2 deletions include/linux/blktrace_api.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -148,7 +148,7 @@ extern int blk_trace_ioctl(struct block_device *, unsigned, char __user *);
extern void blk_trace_shutdown(struct request_queue *);
extern void __blk_add_trace(struct blk_trace *, sector_t, int, int, u32, int, int, void *);
extern int do_blk_trace_setup(struct request_queue *q,
struct block_device *bdev, struct blk_user_trace_setup *buts);
char *name, dev_t dev, struct blk_user_trace_setup *buts);


/**
Expand Down Expand Up @@ -282,6 +282,11 @@ static inline void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
__blk_add_trace(bt, from, bio->bi_size, bio->bi_rw, BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE), sizeof(r), &r);
}

extern int blk_trace_setup(request_queue_t *q, char *name, dev_t dev,
char __user *arg);
extern int blk_trace_startstop(request_queue_t *q, int start);
extern int blk_trace_remove(request_queue_t *q);

#else /* !CONFIG_BLK_DEV_IO_TRACE */
#define blk_trace_ioctl(bdev, cmd, arg) (-ENOTTY)
#define blk_trace_shutdown(q) do { } while (0)
Expand All @@ -290,7 +295,10 @@ static inline void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
#define blk_add_trace_generic(q, rq, rw, what) do { } while (0)
#define blk_add_trace_pdu_int(q, what, bio, pdu) do { } while (0)
#define blk_add_trace_remap(q, bio, dev, f, t) do {} while (0)
#define do_blk_trace_setup(q, bdev, buts) (-ENOTTY)
#define do_blk_trace_setup(q, name, dev, buts) (-ENOTTY)
#define blk_trace_setup(q, name, dev, arg) (-ENOTTY)
#define blk_trace_startstop(q, start) (-ENOTTY)
#define blk_trace_remove(q) (-ENOTTY)
#endif /* CONFIG_BLK_DEV_IO_TRACE */
#endif /* __KERNEL__ */
#endif

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