Messages in this thread | | | Date | Mon, 11 Sep 2023 11:54:32 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH AUTOSEL 6.1 20/22] block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset |
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Hi!
> From: Kent Overstreet <kent.overstreet@linux.dev> > > [ Upstream commit 168145f617d57bf4e474901b7ffa869337a802e6 ] > > 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.
We are certainly not going to backport bcachefs to -stable. Please drop.
BR, Pavel
> +++ b/block/bio.c > @@ -1198,7 +1198,7 @@ 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; > > /* > @@ -1223,10 +1223,12 @@ 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;
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