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block: remove __bio_kmap_atomic

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This helper doesn't buy us much over calling kmap_atomic directly.
In fact in the only caller it does a bit of useless work as the
caller already has the bvec at hand, and said caller would even
buggy for a multi-segment bio due to the use of this helper.

So just remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2017-11-08 19:13:48 +01:00 committed by Jens Axboe
parent 83f5f7ed72
commit d004a5e7d4
4 changed files with 8 additions and 21 deletions
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11
Documentation/block/biodoc.txt
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@ -216,10 +216,9 @@ may need to abort DMA operations and revert to PIO for the transfer, in
which case a virtual mapping of the page is required. For SCSI it is also
done in some scenarios where the low level driver cannot be trusted to
handle a single sg entry correctly. The driver is expected to perform the
kmaps as needed on such occasions using the bio_kmap_irq and friends
routines as appropriate. A driver could also use the blk_queue_bounce()
routine on its own to bounce highmem i/o to low memory for specific requests
if so desired.
kmaps as needed on such occasions as appropriate. A driver could also use
the blk_queue_bounce() routine on its own to bounce highmem i/o to low
memory for specific requests if so desired.
iii. The i/o scheduler algorithm itself can be replaced/set as appropriate
@ -1137,8 +1136,8 @@ use dma_map_sg for scatter gather) to be able to ship it to the driver. For
PIO drivers (or drivers that need to revert to PIO transfer once in a
while (IDE for example)), where the CPU is doing the actual data
transfer a virtual mapping is needed. If the driver supports highmem I/O,
(Sec 1.1, (ii) ) it needs to use __bio_kmap_atomic or similar to
temporarily map a bio into the virtual address space.
(Sec 1.1, (ii) ) it needs to use kmap_atomic or similar to temporarily map
a bio into the virtual address space.
8. Prior/Related/Impacted patches

4
arch/xtensa/platforms/iss/simdisk.c
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@ -110,13 +110,13 @@ static blk_qc_t simdisk_make_request(struct request_queue *q, struct bio *bio)
sector_t sector = bio->bi_iter.bi_sector;
bio_for_each_segment(bvec, bio, iter) {
char *buffer = __bio_kmap_atomic(bio, iter);
char *buffer = kmap_atomic(bvec.bv_page) + bvec.bv_offset;
unsigned len = bvec.bv_len >> SECTOR_SHIFT;
simdisk_transfer(dev, sector, len, buffer,
bio_data_dir(bio) == WRITE);
sector += len;
__bio_kunmap_atomic(buffer);
kunmap_atomic(buffer)
}
bio_endio(bio);

2
block/blk-settings.c
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@ -157,7 +157,7 @@ EXPORT_SYMBOL(blk_set_stacking_limits);
* Caveat:
* The driver that does this *must* be able to deal appropriately
* with buffers in "highmemory". This can be accomplished by either calling
* __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
* kmap_atomic() to get a temporary kernel mapping, or by calling
* blk_queue_bounce() to create a buffer in normal memory.
**/
void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)

12
include/linux/bio.h
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@ -128,18 +128,6 @@ static inline void *bio_data(struct bio *bio)
*/
#define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
/*
* queues that have highmem support enabled may still need to revert to
* PIO transfers occasionally and thus map high pages temporarily. For
* permanent PIO fall back, user is probably better off disabling highmem
* I/O completely on that queue (see ide-dma for example)
*/
#define __bio_kmap_atomic(bio, iter) \
(kmap_atomic(bio_iter_iovec((bio), (iter)).bv_page) + \
bio_iter_iovec((bio), (iter)).bv_offset)
#define __bio_kunmap_atomic(addr) kunmap_atomic(addr)
/*
* merge helpers etc
*/