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>

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>
Tejun Heo · Jens Axboe
1 parent 34b7d2c957
Showing 4 changed files with 17 additions and 16 deletions Side-by-side Diff
block/blk-core.c
block/blk-map.c
block/blk-merge.c
include/linux/blkdev.h
@@ -127,7 +127,7 @@
 	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 @@
 		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 @@
  
 		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 @@
 		 * 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 @@
 		 * can find how many bytes remain in the request
 		 * later.
 		 */
-		req->data_len = 0;
+		req->__data_len = 0;
 		return false;
 	}
  
  
@@ -1892,12 +1892,12 @@
 		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 @@
 	 */
 	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 @@
 		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)
@@ -20,7 +20,7 @@
 		rq->biotail->bi_next = bio;
 		rq->biotail = bio;
  
-		rq->data_len += bio->bi_size;
+		rq->__data_len += bio->bi_size;
 	}
 	return 0;
 }
@@ -370,7 +370,7 @@
 	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);
  
@@ -166,8 +166,9 @@
 	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 @@
  */
 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)
...	...	@@ -127,7 +127,7 @@
127	127	INIT_LIST_HEAD(&rq->timeout_list);
128	128	rq->cpu = -1;
129	129	rq->q = q;
130		- rq->sector = (sector_t) -1;
	130	+ rq->__sector = (sector_t) -1;
131	131	INIT_HLIST_NODE(&rq->hash);
132	132	RB_CLEAR_NODE(&rq->rb_node);
133	133	rq->cmd = rq->__cmd;
...	...	@@ -1095,7 +1095,7 @@
1095	1095	req->cmd_flags \|= REQ_NOIDLE;
1096	1096
1097	1097	req->errors = 0;
1098		- req->sector = bio->bi_sector;
	1098	+ req->__sector = bio->bi_sector;
1099	1099	req->ioprio = bio_prio(bio);
1100	1100	blk_rq_bio_prep(req->q, req, bio);
1101	1101	}
...	...	@@ -1143,7 +1143,7 @@
1143	1143
1144	1144	req->biotail->bi_next = bio;
1145	1145	req->biotail = bio;
1146		- req->data_len += bytes;
	1146	+ req->__data_len += bytes;
1147	1147	req->ioprio = ioprio_best(req->ioprio, prio);
1148	1148	if (!blk_rq_cpu_valid(req))
1149	1149	req->cpu = bio->bi_comp_cpu;
...	...	@@ -1169,8 +1169,8 @@
1169	1169	* not touch req->buffer either...
1170	1170	*/
1171	1171	req->buffer = bio_data(bio);
1172		- req->sector = bio->bi_sector;
1173		- req->data_len += bytes;
	1172	+ req->__sector = bio->bi_sector;
	1173	+ req->__data_len += bytes;
1174	1174	req->ioprio = ioprio_best(req->ioprio, prio);
1175	1175	if (!blk_rq_cpu_valid(req))
1176	1176	req->cpu = bio->bi_comp_cpu;
...	...	@@ -1878,7 +1878,7 @@
1878	1878	* can find how many bytes remain in the request
1879	1879	* later.
1880	1880	*/
1881		- req->data_len = 0;
	1881	+ req->__data_len = 0;
1882	1882	return false;
1883	1883	}
1884	1884
1885	1885
...	...	@@ -1892,12 +1892,12 @@
1892	1892	bio_iovec(bio)->bv_len -= nr_bytes;
1893	1893	}
1894	1894
1895		- req->data_len -= total_bytes;
	1895	+ req->__data_len -= total_bytes;
1896	1896	req->buffer = bio_data(req->bio);
1897	1897
1898	1898	/* update sector only for requests with clear definition of sector */
1899	1899	if (blk_fs_request(req) \|\| blk_discard_rq(req))
1900		- req->sector += total_bytes >> 9;
	1900	+ req->__sector += total_bytes >> 9;
1901	1901
1902	1902	/*
1903	1903	* If total number of sectors is less than the first segment
...	...	@@ -1905,7 +1905,7 @@
1905	1905	*/
1906	1906	if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
1907	1907	printk(KERN_ERR "blk: request botched\n");
1908		- req->data_len = blk_rq_cur_bytes(req);
	1908	+ req->__data_len = blk_rq_cur_bytes(req);
1909	1909	}
1910	1910
1911	1911	/* recalculate the number of segments */
...	...	@@ -2032,7 +2032,7 @@
2032	2032	rq->nr_phys_segments = bio_phys_segments(q, bio);
2033	2033	rq->buffer = bio_data(bio);
2034	2034	}
2035		- rq->data_len = bio->bi_size;
	2035	+ rq->__data_len = bio->bi_size;
2036	2036	rq->bio = rq->biotail = bio;
2037	2037
2038	2038	if (bio->bi_bdev)
...	...	@@ -20,7 +20,7 @@
20	20	rq->biotail->bi_next = bio;
21	21	rq->biotail = bio;
22	22
23		- rq->data_len += bio->bi_size;
	23	+ rq->__data_len += bio->bi_size;
24	24	}
25	25	return 0;
26	26	}
...	...	@@ -370,7 +370,7 @@
370	370	req->biotail->bi_next = next->bio;
371	371	req->biotail = next->biotail;
372	372
373		- req->data_len += blk_rq_bytes(next);
	373	+ req->__data_len += blk_rq_bytes(next);
374	374
375	375	elv_merge_requests(q, req, next);
376	376
...	...	@@ -166,8 +166,9 @@
166	166	enum rq_cmd_type_bits cmd_type;
167	167	unsigned long atomic_flags;
168	168
169		- sector_t sector; /* sector cursor */
170		- unsigned int data_len; /* total data len, don't access directly */
	169	+ /* the following two fields are internal, NEVER access directly */
	170	+ sector_t __sector; /* sector cursor */
	171	+ unsigned int __data_len; /* total data len */
171	172
172	173	struct bio *bio;
173	174	struct bio *biotail;
174	175
...	...	@@ -828,12 +829,12 @@
828	829	*/
829	830	static inline sector_t blk_rq_pos(const struct request *rq)
830	831	{
831		- return rq->sector;
	832	+ return rq->__sector;
832	833	}
833	834
834	835	static inline unsigned int blk_rq_bytes(const struct request *rq)
835	836	{
836		- return rq->data_len;
	837	+ return rq->__data_len;
837	838	}
838	839
839	840	static inline int blk_rq_cur_bytes(const struct request *rq)