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 <fujita.tomonori@lab.ntt.co.jp>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index e6fdb28..5d09f8c 100644 (file)
--- 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
index d17032c..08df1ea 100644 (file)
--- 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 */