- add varlen_cdb and varlen_cdb_len to hold a large user cdb
if needed. They start as empty. Allocation of buffer must
be done by user and held until request execution is done.
- Since there can be either a fix_length command up to 16 bytes
or a variable_length, larger then 16 bytes, commands but never
both, we hold the two types in a union to save space. The
presence of varlen_cdb_len and cmd_len==0 signals a varlen_cdb
mode.
- Please use added rq_{set,get}_varlen_cdb() to set every thing
up in a way that will not confuse drivers that do not support
varlen_cdb's.
- Note that this patch does not add any size to struct request
since the unsigned cmd_len is split here to 2 ushorts, which
is more then enough.
Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
---
block/ll_rw_blk.c | 2 ++
include/linux/blkdev.h | 27 +++++++++++++++++++++++++--
2 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 8b91994..e80179b 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -261,6 +261,8 @@ static void rq_init(struct request_queue *q, struct request *rq)
rq->end_io_data = NULL;
rq->completion_data = NULL;
rq->next_rq = NULL;
+ rq->varlen_cdb_len = 0;
+ rq->varlen_cdb = NULL;
}
/**
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d18ee67..aa3090c 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -287,8 +287,15 @@ 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 short varlen_cdb_len; /* length of varlen_cdb buffer */
+ union {
+ unsigned char cmd[BLK_MAX_CDB];
+ unsigned char *varlen_cdb;/* an optional variable-length cdb.
+ * points to a user buffer that must
+ * be valid until end of request
+ */
+ };
unsigned int data_len;
unsigned int sense_len;
@@ -550,6 +557,22 @@ enum {
#define rq_is_sync(rq) (rq_data_dir((rq)) == READ || (rq)->cmd_flags & REQ_RW_SYNC)
#define rq_is_meta(rq) ((rq)->cmd_flags & REQ_RW_META)
+static inline void rq_set_varlen_cdb(struct request *rq, u8 *cdb, short cdb_len)
+{
+ rq->cmd_len = 0; /* Make sure legacy drivers don't get confused */
+ rq->varlen_cdb_len = cdb_len;
+ rq->varlen_cdb = cdb;
+}
+
+/* If ! a varlen_cdb than return NULL */
+static inline u8 *rq_get_varlen_cdb(struct request *rq)
+{
+ if (!rq->cmd_len && rq->varlen_cdb_len)
+ return rq->varlen_cdb;
+ else
+ return NULL;
+}
+
static inline int blk_queue_full(struct request_queue *q, int rw)
{
if (rw == READ)
--
1.5.3.3
-
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