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>

1 files changed, 13 insertions, 11 deletions

diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index d960889e92ef..267edc4017ee 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -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, ...);
 
 /**
@@ -193,6 +194,7 @@ 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);
@@ -200,15 +202,15 @@ 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