block: hide request sector and data_len

Block low level drivers for some reason have been pretty good at
abusing block layer API.  Especially struct request's fields tend to
get violated in all possible ways.  Make it clear that low level
drivers MUST NOT access or manipulate rq->sector and rq->data_len
directly by prefixing them with double underscores.

This change is also necessary to break build of out-of-tree codes
which assume the previous block API where internal fields can be
manipulated and rq->data_len carries residual count on completion.

[ Impact: hide internal fields, block API change ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index 3596ca71909b42ec5ea96230ac4cc24d5d1cfe6b..6226a380fb6d598913a9e68700be79662223bbde 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -127,7 +127,7 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
        INIT_LIST_HEAD(&rq->timeout_list);
        rq->cpu = -1;
        rq->q = q;
-       rq->sector = (sector_t) -1;
+       rq->__sector = (sector_t) -1;
        INIT_HLIST_NODE(&rq->hash);
        RB_CLEAR_NODE(&rq->rb_node);
        rq->cmd = rq->__cmd;
@@ -1095,7 +1095,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
                req->cmd_flags |= REQ_NOIDLE;
 
        req->errors = 0;
-       req->sector = bio->bi_sector;
+       req->__sector = bio->bi_sector;
        req->ioprio = bio_prio(bio);
        blk_rq_bio_prep(req->q, req, bio);
 }
@@ -1143,7 +1143,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 
                req->biotail->bi_next = bio;
                req->biotail = bio;
-               req->data_len += bytes;
+               req->__data_len += bytes;
                req->ioprio = ioprio_best(req->ioprio, prio);
                if (!blk_rq_cpu_valid(req))
                        req->cpu = bio->bi_comp_cpu;
@@ -1169,8 +1169,8 @@ static int __make_request(struct request_queue *q, struct bio *bio)
                 * not touch req->buffer either...
                 */
                req->buffer = bio_data(bio);
-               req->sector = bio->bi_sector;
-               req->data_len += bytes;
+               req->__sector = bio->bi_sector;
+               req->__data_len += bytes;
                req->ioprio = ioprio_best(req->ioprio, prio);
                if (!blk_rq_cpu_valid(req))
                        req->cpu = bio->bi_comp_cpu;
@@ -1878,7 +1878,7 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
                 * can find how many bytes remain in the request
                 * later.
                 */
-               req->data_len = 0;
+               req->__data_len = 0;
                return false;
        }
 
@@ -1892,12 +1892,12 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
                bio_iovec(bio)->bv_len -= nr_bytes;
        }
 
-       req->data_len -= total_bytes;
+       req->__data_len -= total_bytes;
        req->buffer = bio_data(req->bio);
 
        /* update sector only for requests with clear definition of sector */
        if (blk_fs_request(req) || blk_discard_rq(req))
-               req->sector += total_bytes >> 9;
+               req->__sector += total_bytes >> 9;
 
        /*
         * If total number of sectors is less than the first segment
@@ -1905,7 +1905,7 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
         */
        if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
                printk(KERN_ERR "blk: request botched\n");
-               req->data_len = blk_rq_cur_bytes(req);
+               req->__data_len = blk_rq_cur_bytes(req);
        }
 
        /* recalculate the number of segments */
@@ -2032,7 +2032,7 @@ void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
                rq->nr_phys_segments = bio_phys_segments(q, bio);
                rq->buffer = bio_data(bio);
        }
-       rq->data_len = bio->bi_size;
+       rq->__data_len = bio->bi_size;
        rq->bio = rq->biotail = bio;
 
        if (bio->bi_bdev)

diff --git a/block/blk-map.c b/block/blk-map.c
index 694fefad34e7cecc2f294b8e8eb494602ace1d14..56082bea45041c0f2ef68ad7c99a3d40288bc4e4 100644 (file)
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -20,7 +20,7 @@ int blk_rq_append_bio(struct request_queue *q, struct request *rq,
                rq->biotail->bi_next = bio;
                rq->biotail = bio;
 
-               rq->data_len += bio->bi_size;
+               rq->__data_len += bio->bi_size;
        }
        return 0;
 }

diff --git a/block/blk-merge.c b/block/blk-merge.c
index b8df66aef0f84a0bac63376985dd237aa1f18977..4974dd5767e516f7f2bd507fa10a55cb0da62bd5 100644 (file)
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -370,7 +370,7 @@ static int attempt_merge(struct request_queue *q, struct request *req,
        req->biotail->bi_next = next->bio;
        req->biotail = next->biotail;
 
-       req->data_len += blk_rq_bytes(next);
+       req->__data_len += blk_rq_bytes(next);
 
        elv_merge_requests(q, req, next);
 

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ce2bf5efa9baed87b32e5e241b160aedae7cfbe3..c75580345700f46faa8ec61fe084836765c82b5f 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -166,8 +166,9 @@ struct request {
        enum rq_cmd_type_bits cmd_type;
        unsigned long atomic_flags;
 
-       sector_t sector;        /* sector cursor */
-       unsigned int data_len;  /* total data len, don't access directly */
+       /* the following two fields are internal, NEVER access directly */
+       sector_t __sector;              /* sector cursor */
+       unsigned int __data_len;        /* total data len */
 
        struct bio *bio;
        struct bio *biotail;
@@ -828,12 +829,12 @@ extern void blkdev_dequeue_request(struct request *req);
  */
 static inline sector_t blk_rq_pos(const struct request *rq)
 {
-       return rq->sector;
+       return rq->__sector;
 }
 
 static inline unsigned int blk_rq_bytes(const struct request *rq)
 {
-       return rq->data_len;
+       return rq->__data_len;
 }
 
 static inline int blk_rq_cur_bytes(const struct request *rq)