blktrace: fix pdu_len when tracing packet command requests

Impact: output all of packet commands - not just the first 4 / 8 bytes

Since commit d7e3c3249ef23b4617393c69fe464765b4ff1645 ("block: add
large command support"), struct request->cmd has been changed from
unsinged char cmd[BLK_MAX_CDB] to unsigned char *cmd.

v1 -> v2: by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

- make sure rq->cmd_len is always intialized, and then we can use
  rq->cmd_len instead of BLK_MAX_CDB.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
LKML-Reference: <49D4507E.2060602@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 2 insertions, 1 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 29bcfac6c688..859879d0a0bf 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -132,6 +132,7 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
         INIT_HLIST_NODE(&rq->hash);
         RB_CLEAR_NODE(&rq->rb_node);
         rq->cmd = rq->__cmd;
+        rq->cmd_len = BLK_MAX_CDB;
         rq->tag = -1;
         rq->ref_count = 1;
 }
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 73d7860b72e2..b32ff446c3fb 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -643,7 +643,7 @@ static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
         if (blk_pc_request(rq)) {
                 what |= BLK_TC_ACT(BLK_TC_PC);
                 __blk_add_trace(bt, 0, rq->data_len, rw, what, rq->errors,
-                                sizeof(rq->cmd), rq->cmd);
+                                rq->cmd_len, rq->cmd);
         } else  {
                 what |= BLK_TC_ACT(BLK_TC_FS);
                 __blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,