| From | Kent Overstreet <> | Subject | [PATCH 10/32] block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset | Date | Tue, 9 May 2023 12:56:35 -0400 |
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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@linux.dev> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org --- 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
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