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block: add a bdev_rw_virt helper 

Add a helper to perform synchronous I/O on a kernel direct map range.
Currently this is implemented in various places in usually not very
efficient ways, so provide a generic helper instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2025-05-07 14:04:26 +02:00 committed by Jens Axboe
parent 850e210d5a
commit 10b1e59cda
2 changed files with 34 additions and 1 deletions
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30
block/bio.c
View File

@ -1319,6 +1319,36 @@ int submit_bio_wait(struct bio *bio)
}
EXPORT_SYMBOL(submit_bio_wait);
/**
* bdev_rw_virt - synchronously read into / write from kernel mapping
* @bdev: block device to access
* @sector: sector to access
* @data: data to read/write
* @len: length in byte to read/write
* @op: operation (e.g. REQ_OP_READ/REQ_OP_WRITE)
*
* Performs synchronous I/O to @bdev for @data/@len. @data must be in
* the kernel direct mapping and not a vmalloc address.
*/
int bdev_rw_virt(struct block_device *bdev, sector_t sector, void *data,
size_t len, enum req_op op)
{
struct bio_vec bv;
struct bio bio;
int error;
if (WARN_ON_ONCE(is_vmalloc_addr(data)))
return -EIO;
bio_init(&bio, bdev, &bv, 1, op);
bio.bi_iter.bi_sector = sector;
bio_add_virt_nofail(&bio, data, len);
error = submit_bio_wait(&bio);
bio_uninit(&bio);
return error;
}
EXPORT_SYMBOL_GPL(bdev_rw_virt);
static void bio_wait_end_io(struct bio *bio)
{
complete(bio->bi_private);

5
include/linux/bio.h
View File

@ -402,7 +402,6 @@ static inline int bio_iov_vecs_to_alloc(struct iov_iter *iter, int max_segs)
struct request_queue;
extern int submit_bio_wait(struct bio *bio);
void bio_init(struct bio *bio, struct block_device *bdev, struct bio_vec *table,
unsigned short max_vecs, blk_opf_t opf);
extern void bio_uninit(struct bio *);
@ -419,6 +418,10 @@ void bio_add_folio_nofail(struct bio *bio, struct folio *folio, size_t len,
size_t off);
void bio_add_virt_nofail(struct bio *bio, void *vaddr, unsigned len);
int submit_bio_wait(struct bio *bio);
int bdev_rw_virt(struct block_device *bdev, sector_t sector, void *data,
size_t len, enum req_op op);
int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
void bio_iov_bvec_set(struct bio *bio, const struct iov_iter *iter);
void __bio_release_pages(struct bio *bio, bool mark_dirty);