bio_iov_iter_get_pages() trims the IO based on the block size of the
block device the IO will be issued to.
However, bcachefs is a multi device filesystem; when we're creating the
bio we don't yet know which block device the bio will be submitted to -
we have to handle the alignment checks elsewhere.
Thus this is needed to avoid a null ptr deref.
Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: linux-block@xxxxxxxxxxxxxxx
---
block/bio.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 1e75840d17..e74a04ea14 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1245,7 +1245,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
struct page **pages = (struct page **)bv;
ssize_t size, left;
unsigned len, i = 0;
- size_t offset, trim;
+ size_t offset;
int ret = 0;
/*
@@ -1274,10 +1274,12 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
nr_pages = DIV_ROUND_UP(offset + size, PAGE_SIZE);
- trim = size & (bdev_logical_block_size(bio->bi_bdev) - 1);
- iov_iter_revert(iter, trim);
+ if (bio->bi_bdev) {
+ size_t trim = size & (bdev_logical_block_size(bio->bi_bdev) - 1);
+ iov_iter_revert(iter, trim);
+ size -= trim;
+ }
- size -= trim;
if (unlikely(!size)) {
ret = -EFAULT;
goto out;
--
2.40.1
