block: advance iov_iter on bio_add_hw_page failure

When the bio's size reaches max_append_sectors, bio_add_hw_page returns
0 then __bio_iov_append_get_pages returns -EINVAL. This is an expected
result of building a small enough bio not to be split in the IO path.
However, iov_iter is not advanced in this case, causing the same pages
are filled for the bio again and again.

Fix the case by properly advancing the iov_iter for already processed
pages.

Fixes: 0512a75b98f8 ("block: Introduce REQ_OP_ZONE_APPEND")
Cc: stable@vger.kernel.org # 5.8+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index e6e26d7..fa01bef 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1044,6 +1044,7 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
        ssize_t size, left;
        unsigned len, i;
        size_t offset;
+       int ret = 0;
 
        if (WARN_ON_ONCE(!max_append_sectors))
                return 0;
@@ -1066,15 +1067,17 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
 
                len = min_t(size_t, PAGE_SIZE - offset, left);
                if (bio_add_hw_page(q, bio, page, len, offset,
-                               max_append_sectors, &same_page) != len)
-                       return -EINVAL;
+                               max_append_sectors, &same_page) != len) {
+                       ret = -EINVAL;
+                       break;
+               }
                if (same_page)
                        put_page(page);
                offset = 0;
        }
 
-       iov_iter_advance(iter, size);
-       return 0;
+       iov_iter_advance(iter, size - left);
+       return ret;
 }
 
 /**