block: remove __bio_kmap_atomic

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>

Documentation/block/biodoc.txt

@@ -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

arch/xtensa/platforms/iss/simdisk.c

@@ -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);

block/blk-settings.c

@@ -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)

include/linux/bio.h

@@ -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
  */