block: ensure bio_iov_add_page can't fail

Adding the page could fail on the bio_full() condition, which checks for
either exceeding the bio's max segments or total size exceeding
UINT_MAX. We already ensure the max segments can't be exceeded, so just
ensure the total size won't reach the limit. This simplifies error
handling and removes unnecessary repeated bio_full() checks.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20220712153256.2202024-2-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index d7c2536..4740ba3 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1165,8 +1165,6 @@ static int bio_iov_add_page(struct bio *bio, struct page *page,
        bool same_page = false;
 
        if (!__bio_try_merge_page(bio, page, len, offset, &same_page)) {
-               if (WARN_ON_ONCE(bio_full(bio, len)))
-                       return -EINVAL;
                __bio_add_page(bio, page, len, offset);
                return 0;
        }
@@ -1228,7 +1226,8 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
         * result to ensure the bio's total size is correct. The remainder of
         * the iov data will be picked up in the next bio iteration.
         */
-       size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
+       size = iov_iter_get_pages(iter, pages, UINT_MAX - bio->bi_iter.bi_size,
+                                 nr_pages, &offset);
        if (size > 0)
                size = ALIGN_DOWN(size, bdev_logical_block_size(bio->bi_bdev));
        if (unlikely(size <= 0))
@@ -1238,16 +1237,16 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
                struct page *page = pages[i];
 
                len = min_t(size_t, PAGE_SIZE - offset, left);
-               if (bio_op(bio) == REQ_OP_ZONE_APPEND)
+               if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
                        ret = bio_iov_add_zone_append_page(bio, page, len,
                                        offset);
-               else
-                       ret = bio_iov_add_page(bio, page, len, offset);
+                       if (ret) {
+                               bio_put_pages(pages + i, left, offset);
+                               break;
+                       }
+               } else
+                       bio_iov_add_page(bio, page, len, offset);
 
-               if (ret) {
-                       bio_put_pages(pages + i, left, offset);
-                       break;
-               }
                offset = 0;
        }