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From: Bart Van Assche <bvanassche@acm.org>
Date: Thu, 1 Aug 2019 15:50:40 -0700
Subject: [PATCH] block: Declare several function pointer arguments 'const'
References: bsc#1156419,jsc#SLE-8281
Git-commit: af2c68fe94e8c0a628519b60ba070c5cf6526a99
Patch-mainline: v5.4-rc1

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 <jthumshirn@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 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 c2b7e19d4cfa..21e3a7292e2a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1241,42 +1241,42 @@ 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;
 
@@ -1291,7 +1291,7 @@ 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;
 }
@@ -1301,7 +1301,7 @@ 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;
 }
@@ -1311,7 +1311,7 @@ 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;
 }
@@ -1321,7 +1321,7 @@ 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;
@@ -1351,7 +1351,7 @@ 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;
@@ -1441,7 +1441,7 @@ 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;
 }
@@ -1552,7 +1552,7 @@ 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;
 }
@@ -1635,7 +1635,7 @@ 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;
 }
-- 
2.16.4