block: add secure discard

Secure discard is the same as discard except that all copies of the
discarded sectors (perhaps created by garbage collection) must also be
erased.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 82499a5..959f8d6 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -710,6 +710,9 @@
 	if (rq->cmd_flags & REQ_DISCARD)
 		rw |= REQ_DISCARD;
 
+	if (rq->cmd_flags & REQ_SECURE)
+		rw |= REQ_SECURE;
+
 	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 		what |= BLK_TC_ACT(BLK_TC_PC);
 		__blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
@@ -1816,6 +1819,8 @@
 		rwbs[i++] = 'S';
 	if (rw & REQ_META)
 		rwbs[i++] = 'M';
+	if (rw & REQ_SECURE)
+		rwbs[i++] = 'E';
 
 	rwbs[i] = '\0';
 }
@@ -1828,6 +1833,9 @@
 	if (rq->cmd_flags & REQ_DISCARD)
 		rw |= REQ_DISCARD;
 
+	if (rq->cmd_flags & REQ_SECURE)
+		rw |= REQ_SECURE;
+
 	bytes = blk_rq_bytes(rq);
 
 	blk_fill_rwbs(rwbs, rw, bytes);