Make it clear to the compiler and also to humans that the functions
that query request queue properties do not modify any member of the
request_queue data structure.

Reviewed-by: Johannes Thumshirn <jthumsh...@suse.de>
Cc: Christoph Hellwig <h...@infradead.org>
Cc: Ming Lei <ming....@redhat.com>
Cc: Hannes Reinecke <h...@suse.com>
Signed-off-by: Bart Van Assche <bvanass...@acm.org>
---
 block/blk-merge.c      |  7 ++++---
 include/linux/blkdev.h | 32 ++++++++++++++++----------------
 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 57f7990b342d..8344d94f13e0 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -144,7 +144,7 @@ static inline unsigned get_max_io_size(struct request_queue 
*q,
        return sectors;
 }
 
-static unsigned get_max_segment_size(struct request_queue *q,
+static unsigned get_max_segment_size(const struct request_queue *q,
                                     unsigned offset)
 {
        unsigned long mask = queue_segment_boundary(q);
@@ -161,8 +161,9 @@ static unsigned get_max_segment_size(struct request_queue 
*q,
  * Split the bvec @bv into segments, and update all kinds of
  * variables.
  */
-static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv,
-               unsigned *nsegs, unsigned *sectors, unsigned max_segs)
+static bool bvec_split_segs(const struct request_queue *q,
+                           const struct bio_vec *bv, unsigned *nsegs,
+                           unsigned *sectors, unsigned max_segs)
 {
        unsigned len = bv->bv_len;
        unsigned total_len = 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1ef375dafb1c..96a29a72fd4a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1232,42 +1232,42 @@ enum blk_default_limits {
        BLK_SEG_BOUNDARY_MASK   = 0xFFFFFFFFUL,
 };
 
-static inline unsigned long queue_segment_boundary(struct request_queue *q)
+static inline unsigned long queue_segment_boundary(const struct request_queue 
*q)
 {
        return q->limits.seg_boundary_mask;
 }
 
-static inline unsigned long queue_virt_boundary(struct request_queue *q)
+static inline unsigned long queue_virt_boundary(const struct request_queue *q)
 {
        return q->limits.virt_boundary_mask;
 }
 
-static inline unsigned int queue_max_sectors(struct request_queue *q)
+static inline unsigned int queue_max_sectors(const struct request_queue *q)
 {
        return q->limits.max_sectors;
 }
 
-static inline unsigned int queue_max_hw_sectors(struct request_queue *q)
+static inline unsigned int queue_max_hw_sectors(const struct request_queue *q)
 {
        return q->limits.max_hw_sectors;
 }
 
-static inline unsigned short queue_max_segments(struct request_queue *q)
+static inline unsigned short queue_max_segments(const struct request_queue *q)
 {
        return q->limits.max_segments;
 }
 
-static inline unsigned short queue_max_discard_segments(struct request_queue 
*q)
+static inline unsigned short queue_max_discard_segments(const struct 
request_queue *q)
 {
        return q->limits.max_discard_segments;
 }
 
-static inline unsigned int queue_max_segment_size(struct request_queue *q)
+static inline unsigned int queue_max_segment_size(const struct request_queue 
*q)
 {
        return q->limits.max_segment_size;
 }
 
-static inline unsigned short queue_logical_block_size(struct request_queue *q)
+static inline unsigned short queue_logical_block_size(const struct 
request_queue *q)
 {
        int retval = 512;
 
@@ -1282,7 +1282,7 @@ static inline unsigned short 
bdev_logical_block_size(struct block_device *bdev)
        return queue_logical_block_size(bdev_get_queue(bdev));
 }
 
-static inline unsigned int queue_physical_block_size(struct request_queue *q)
+static inline unsigned int queue_physical_block_size(const struct 
request_queue *q)
 {
        return q->limits.physical_block_size;
 }
@@ -1292,7 +1292,7 @@ static inline unsigned int 
bdev_physical_block_size(struct block_device *bdev)
        return queue_physical_block_size(bdev_get_queue(bdev));
 }
 
-static inline unsigned int queue_io_min(struct request_queue *q)
+static inline unsigned int queue_io_min(const struct request_queue *q)
 {
        return q->limits.io_min;
 }
@@ -1302,7 +1302,7 @@ static inline int bdev_io_min(struct block_device *bdev)
        return queue_io_min(bdev_get_queue(bdev));
 }
 
-static inline unsigned int queue_io_opt(struct request_queue *q)
+static inline unsigned int queue_io_opt(const struct request_queue *q)
 {
        return q->limits.io_opt;
 }
@@ -1312,7 +1312,7 @@ static inline int bdev_io_opt(struct block_device *bdev)
        return queue_io_opt(bdev_get_queue(bdev));
 }
 
-static inline int queue_alignment_offset(struct request_queue *q)
+static inline int queue_alignment_offset(const struct request_queue *q)
 {
        if (q->limits.misaligned)
                return -1;
@@ -1342,7 +1342,7 @@ static inline int bdev_alignment_offset(struct 
block_device *bdev)
        return q->limits.alignment_offset;
 }
 
-static inline int queue_discard_alignment(struct request_queue *q)
+static inline int queue_discard_alignment(const struct request_queue *q)
 {
        if (q->limits.discard_misaligned)
                return -1;
@@ -1432,7 +1432,7 @@ static inline sector_t bdev_zone_sectors(struct 
block_device *bdev)
        return 0;
 }
 
-static inline int queue_dma_alignment(struct request_queue *q)
+static inline int queue_dma_alignment(const struct request_queue *q)
 {
        return q ? q->dma_alignment : 511;
 }
@@ -1543,7 +1543,7 @@ static inline void 
blk_queue_max_integrity_segments(struct request_queue *q,
 }
 
 static inline unsigned short
-queue_max_integrity_segments(struct request_queue *q)
+queue_max_integrity_segments(const struct request_queue *q)
 {
        return q->limits.max_integrity_segments;
 }
@@ -1626,7 +1626,7 @@ static inline void 
blk_queue_max_integrity_segments(struct request_queue *q,
                                                    unsigned int segs)
 {
 }
-static inline unsigned short queue_max_integrity_segments(struct request_queue 
*q)
+static inline unsigned short queue_max_integrity_segments(const struct 
request_queue *q)
 {
        return 0;
 }
-- 
2.22.0.770.g0f2c4a37fd-goog

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