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authorMing Lei <ming.lei@redhat.com>2019-03-28 11:05:31 +0800
committerJens Axboe <axboe@kernel.dk>2019-04-01 12:11:48 -0600
commit81ba6abd2bcd2812974bd3a4c43d1d032acfa751 (patch)
tree2223771a69cbddbc0a640244f75aabb5cfef6f8d /drivers/block/loop.c
parentf6970f83ef79503cb24ca8324e5cfa1188674f85 (diff)
downloadlinux-81ba6abd2bcd2812974bd3a4c43d1d032acfa751.tar.bz2
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 <hch@infradead.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block/loop.c')
-rw-r--r--drivers/block/loop.c16
1 files 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;