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Commit b6207430 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: never take page references for ITER_BVEC 



If we pass pages through an iov_iter we always already have a reference
in the caller.  Thus remove the ITER_BVEC_FLAG_NO_REF and don't take
reference to pages by default for bvec backed iov_iters.

Reviewed-by: default avatarMinwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d7c8aa85

block/bio.c

+1 −13
Original line number Diff line number Diff line
@@ -836,15 +836,6 @@ int bio_add_page(struct bio *bio, struct page *page, 
}

EXPORT_SYMBOL(bio_add_page);



static void bio_get_pages(struct bio *bio)

{

	struct bvec_iter_all iter_all;

	struct bio_vec *bvec;



	bio_for_each_segment_all(bvec, bio, iter_all)

		get_page(bvec->bv_page);

}



void bio_release_pages(struct bio *bio, bool mark_dirty)

{

	struct bvec_iter_all iter_all;
@@ -960,11 +951,8 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) 
			ret = __bio_iov_iter_get_pages(bio, iter);

	} while (!ret && iov_iter_count(iter) && !bio_full(bio));



	if (iov_iter_bvec_no_ref(iter))

	if (is_bvec)

		bio_set_flag(bio, BIO_NO_PAGE_REF);

	else if (is_bvec)

		bio_get_pages(bio);



	return bio->bi_vcnt ? 0 : ret;

}

drivers/block/loop.c

+4 −12
Original line number Diff line number Diff line
@@ -264,20 +264,12 @@ lo_do_transfer(struct loop_device *lo, int cmd, 
	return ret;

}



static inline void loop_iov_iter_bvec(struct iov_iter *i,

		unsigned int direction, const struct bio_vec *bvec,

		unsigned long nr_segs, size_t count)

{

	iov_iter_bvec(i, direction, bvec, nr_segs, count);

	i->type |= ITER_BVEC_FLAG_NO_REF;

}



static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)

{

	struct iov_iter i;

	ssize_t bw;



	loop_iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len);

	iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len);



	file_start_write(file);

	bw = vfs_iter_write(file, &i, ppos, 0);
@@ -355,7 +347,7 @@ static int lo_read_simple(struct loop_device *lo, struct request *rq, 
	ssize_t len;



	rq_for_each_segment(bvec, rq, iter) {

		loop_iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len);

		iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len);

		len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);

		if (len < 0)

			return len;
@@ -396,7 +388,7 @@ static int lo_read_transfer(struct loop_device *lo, struct request *rq, 
		b.bv_offset = 0;

		b.bv_len = bvec.bv_len;



		loop_iov_iter_bvec(&i, READ, &b, 1, b.bv_len);

		iov_iter_bvec(&i, READ, &b, 1, b.bv_len);

		len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);

		if (len < 0) {

			ret = len;
@@ -563,7 +555,7 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, 
	}

	atomic_set(&cmd->ref, 2);



	loop_iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));

	iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));

	iter.iov_offset = offset;



	cmd->iocb.ki_pos = pos;

fs/io_uring.c

+0 −3
Original line number Diff line number Diff line
@@ -997,9 +997,6 @@ static int io_import_fixed(struct io_ring_ctx *ctx, int rw, 
	iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);

	if (offset)

		iov_iter_advance(iter, offset);



	/* don't drop a reference to these pages */

	iter->type |= ITER_BVEC_FLAG_NO_REF;

	return 0;

}

include/linux/uio.h

+1 −9
Original line number Diff line number Diff line
@@ -19,9 +19,6 @@ struct kvec { 
};



enum iter_type {

	/* set if ITER_BVEC doesn't hold a bv_page ref */

	ITER_BVEC_FLAG_NO_REF = 2,



	/* iter types */

	ITER_IOVEC = 4,

	ITER_KVEC = 8,
@@ -56,7 +53,7 @@ struct iov_iter { 


static inline enum iter_type iov_iter_type(const struct iov_iter *i)

{

	return i->type & ~(READ | WRITE | ITER_BVEC_FLAG_NO_REF);

	return i->type & ~(READ | WRITE);

}



static inline bool iter_is_iovec(const struct iov_iter *i)
@@ -89,11 +86,6 @@ static inline unsigned char iov_iter_rw(const struct iov_iter *i) 
	return i->type & (READ | WRITE);

}



static inline bool iov_iter_bvec_no_ref(const struct iov_iter *i)

{

	return (i->type & ITER_BVEC_FLAG_NO_REF) != 0;

}



/*

 * Total number of bytes covered by an iovec.

 *