block: ensure that bio_add_page() always accepts a page for an empty bio

With commit 762380ad9322 added support for chunk sizes and no merging
across them, it broke the rule of always allowing adding of a single
page to an empty bio. So relax the restriction a bit to allow for that,
similarly to what we have always done.

This fixes a crash with mkfs.xfs and 512b sector sizes on NVMe.

Reported-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/block/bio.c b/block/bio.c
index 97e832cc9b9c..2d64488e51c6 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -849,8 +849,13 @@ int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
                  unsigned int offset)
 {
         struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+        unsigned int max_sectors;
 
-        return __bio_add_page(q, bio, page, len, offset, blk_max_size_offset(q, bio->bi_iter.bi_sector));
+        max_sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector);
+        if ((max_sectors < (len >> 9)) && !bio->bi_iter.bi_size)
+                max_sectors = len >> 9;
+
+        return __bio_add_page(q, bio, page, len, offset, max_sectors);
 }
 EXPORT_SYMBOL(bio_add_page);