Commit 3e1a88ec authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

bio: add a helper calculating nr segments to alloc 



Add a helper function calculating the number of bvec segments we need to
allocate to construct a bio. It doesn't change anything functionally,
but will be used to not duplicate special cases in the future.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 54c8195b

fs/block_dev.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -416,7 +416,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) 
		dio->size += bio->bi_iter.bi_size;

		dio->size += bio->bi_iter.bi_size;

		pos += bio->bi_iter.bi_size;

		pos += bio->bi_iter.bi_size;





		nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);

		nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_PAGES);

		if (!nr_pages) {

		if (!nr_pages) {

			bool polled = false;

			bool polled = false;
@@ -481,9 +481,10 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 
{

{

	int nr_pages;

	int nr_pages;





	nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1);

	if (!iov_iter_count(iter))

	if (!nr_pages)

		return 0;

		return 0;



	nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_PAGES + 1);

	if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)

	if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)

		return __blkdev_direct_IO_simple(iocb, iter, nr_pages);

		return __blkdev_direct_IO_simple(iocb, iter, nr_pages);

fs/iomap/direct-io.c

+4 −5
Original line number Original line Diff line number Diff line
@@ -250,11 +250,8 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, 
	orig_count = iov_iter_count(dio->submit.iter);

	orig_count = iov_iter_count(dio->submit.iter);

	iov_iter_truncate(dio->submit.iter, length);

	iov_iter_truncate(dio->submit.iter, length);





	nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES);

	if (!iov_iter_count(dio->submit.iter))

	if (nr_pages <= 0) {

		ret = nr_pages;

		goto out;

		goto out;

	}





	if (need_zeroout) {

	if (need_zeroout) {

		/* zero out from the start of the block to the write offset */

		/* zero out from the start of the block to the write offset */
@@ -263,6 +260,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, 
			iomap_dio_zero(dio, iomap, pos - pad, pad);

			iomap_dio_zero(dio, iomap, pos - pad, pad);

	}

	}





	nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_PAGES);

	do {

	do {

		size_t n;

		size_t n;

		if (dio->error) {

		if (dio->error) {
@@ -308,7 +306,8 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, 
		dio->size += n;

		dio->size += n;

		copied += n;

		copied += n;





		nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES);

		nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter,

						 BIO_MAX_PAGES);

		iomap_dio_submit_bio(dio, iomap, bio, pos);

		iomap_dio_submit_bio(dio, iomap, bio, pos);

		pos += n;

		pos += n;

	} while (nr_pages);

	} while (nr_pages);

include/linux/bio.h

+10 −0
Original line number Original line Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/ioprio.h>

#include <linux/ioprio.h>

/* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */

/* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */

#include <linux/blk_types.h>

#include <linux/blk_types.h>

#include <linux/uio.h>





#define BIO_DEBUG

#define BIO_DEBUG
@@ -441,6 +442,15 @@ static inline void bio_wouldblock_error(struct bio *bio) 
	bio_endio(bio);

	bio_endio(bio);

}

}





/*

 * Calculate number of bvec segments that should be allocated to fit data

 * pointed by @iter.

 */

static inline int bio_iov_vecs_to_alloc(struct iov_iter *iter, int max_segs)

{

	return iov_iter_npages(iter, max_segs);

}



struct request_queue;

struct request_queue;





extern int submit_bio_wait(struct bio *bio);

extern int submit_bio_wait(struct bio *bio);