block: add large command support

This patch changes rq->cmd from the static array to a pointer to support large commands. We rarely handle large commands. So for optimization, a struct request still has a static array for a command. rq_init sets rq->cmd pointer to the static array. Signed-off-by: FUJITA Tomonori <[email protected]> Cc: Jens Axboe <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
chewitt · Apr 29, 2008 · d7e3c32 · d7e3c32
1 parent d34c87e
commit d7e3c32
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Showing 2 changed files with 4 additions and 2 deletions.
diff --git a/block/blk-core.c b/block/blk-core.c
@@ -117,6 +117,7 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
 	rq->sector = rq->hard_sector = (sector_t) -1;
 	INIT_HLIST_NODE(&rq->hash);
 	RB_CLEAR_NODE(&rq->rb_node);
+	rq->cmd = rq->__cmd;
 	rq->tag = -1;
 	rq->ref_count = 1;
 }

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
@@ -215,8 +215,9 @@ struct request {
 	/*
 	 * when request is used as a packet command carrier
 	 */
-	unsigned int cmd_len;
-	unsigned char cmd[BLK_MAX_CDB];
+	unsigned short cmd_len;
+	unsigned char __cmd[BLK_MAX_CDB];
+	unsigned char *cmd;
 
 	unsigned int data_len;
 	unsigned int extra_len;	/* length of alignment and padding */