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block: refactor the bounce buffering code

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Get rid of all the PFN arithmetics and just use an enum for the two
remaining options, and use PageHighMem for the actual bounce decision.

Add a fast path to entirely avoid the call for the common case of a queue
not using the legacy bouncing code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210331073001.46776-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
2021-03-31 09:30:00 +02:00
committed by Jens Axboe
parent ce288e0535
commit 9bb33f24ab
5 changed files with 38 additions and 90 deletions
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29
include/linux/blkdev.h
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@@ -313,8 +313,17 @@ enum blk_zoned_model {
BLK_ZONED_HM, /* Host-managed zoned block device */
};
/*
* BLK_BOUNCE_NONE: never bounce (default)
* BLK_BOUNCE_HIGH: bounce all highmem pages
*/
enum blk_bounce {
BLK_BOUNCE_NONE,
BLK_BOUNCE_HIGH,
};
struct queue_limits {
unsigned long bounce_pfn;
enum blk_bounce bounce;
unsigned long seg_boundary_mask;
unsigned long virt_boundary_mask;
@@ -835,22 +844,6 @@ static inline unsigned int blk_queue_depth(struct request_queue *q)
return q->nr_requests;
}
extern unsigned long blk_max_low_pfn, blk_max_pfn;
/*
* standard bounce addresses:
*
* BLK_BOUNCE_HIGH : bounce all highmem pages
* BLK_BOUNCE_ANY : don't bounce anything
*/
#if BITS_PER_LONG == 32
#define BLK_BOUNCE_HIGH ((u64)blk_max_low_pfn << PAGE_SHIFT)
#else
#define BLK_BOUNCE_HIGH -1ULL
#endif
#define BLK_BOUNCE_ANY (-1ULL)
/*
* default timeout for SG_IO if none specified
*/
@@ -1134,7 +1127,7 @@ extern void blk_abort_request(struct request *);
* Access functions for manipulating queue properties
*/
extern void blk_cleanup_queue(struct request_queue *);
extern void blk_queue_bounce_limit(struct request_queue *, u64);
void blk_queue_bounce_limit(struct request_queue *q, enum blk_bounce limit);
extern void blk_queue_max_hw_sectors(struct request_queue *, unsigned int);
extern void blk_queue_chunk_sectors(struct request_queue *, unsigned int);
extern void blk_queue_max_segments(struct request_queue *, unsigned short);