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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: Kent 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: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Kent Overstreet 2023-08-13 14:26:35 -04:00 committed by Jens Axboe
parent 7ba3792718
commit 168145f617
1 changed files with 6 additions and 4 deletions
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10
block/bio.c
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@ -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);
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;