Commit 168145f6 authored by Kent Overstreet's avatar Kent Overstreet Committed by Jens Axboe
Browse files

block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset 



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: default avatarKent Overstreet <kent.overstreet@linux.dev>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Link: https://lore.kernel.org/r/20230813182636.2966159-3-kent.overstreet@linux.dev


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7ba37927

block/bio.c

+6 −4
Original line number Diff line number Diff line
@@ -1231,7 +1231,7 @@ 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;



	/*
@@ -1260,10 +1260,12 @@ 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);

	if (bio->bi_bdev) {

		size_t trim = size & (bdev_logical_block_size(bio->bi_bdev) - 1);

		iov_iter_revert(iter, trim);



		size -= trim;

	}



	if (unlikely(!size)) {

		ret = -EFAULT;

		goto out;