From 81ba6abd2bcd2812974bd3a4c43d1d032acfa751 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 28 Mar 2019 11:05:31 +0800 Subject: [PATCH] block: loop: mark bvec as ITER_BVEC_FLAG_NO_REF loop is one block device, for any bio submitted to this device, the upper layer does guarantee that pages added to loop's bio won't go away when the bio is in-flight. So mark loop's bvec as ITER_BVEC_FLAG_NO_REF then get_page/put_page can be saved for serving loop's IO. Cc: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- drivers/block/loop.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index c20710e617c2..102d79575895 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -264,12 +264,20 @@ 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; - iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len); + loop_iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len); file_start_write(file); bw = vfs_iter_write(file, &i, ppos, 0); @@ -347,7 +355,7 @@ static int lo_read_simple(struct loop_device *lo, struct request *rq, ssize_t len; rq_for_each_segment(bvec, rq, iter) { - iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len); + loop_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; @@ -388,7 +396,7 @@ static int lo_read_transfer(struct loop_device *lo, struct request *rq, b.bv_offset = 0; b.bv_len = bvec.bv_len; - iov_iter_bvec(&i, READ, &b, 1, b.bv_len); + loop_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; @@ -555,7 +563,7 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, } atomic_set(&cmd->ref, 2); - iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); + loop_iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); iter.iov_offset = offset; cmd->iocb.ki_pos = pos;