blktrace: support per-partition tracing
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 <duyuyang@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
LKML-Reference: <49E42620.4050701@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 2b98195..e932654 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -147,7 +147,7 @@
{
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;
@@ -192,7 +192,7 @@
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();
@@ -407,11 +407,13 @@
* 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;
@@ -480,11 +482,21 @@
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;
@@ -505,6 +517,7 @@
}
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;
@@ -514,7 +527,7 @@
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;
@@ -582,7 +595,7 @@
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;
