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: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index 1cbf2a7c245e8f5723243ef3878f914416d36893..5733b9426231c84a028748cc38aabb1af9d5a111 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -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;
 }
 

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f11b7dc16e9d4075726f1320b80e985031c85c6b..44c9985f352abd0cfb4ddda003302e09f76ce4bd 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -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;

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 86a2bd7219005b149f76b811117d5312ef8a63b8..eb6ab1507913e1e35b65152792221eef92f6821c 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -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;
 }
 

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 2c90a0842ee86d68bb64e6a930bc56c245a487b9..cea1761c567221aad0857e144f2fd0c9f172db84 100644 (file)
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -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.
  *