Re: [PATCH V2] block: fix .bi_size overflow

On 7/1/19 1:14 AM, Ming Lei wrote:

'bio->bi_iter.bi_size' is 'unsigned int', which at most hold 4G - 1 bytes.

Before 07173c3ec276 ("block: enable multipage bvecs"), one bio can include very limited pages, and usually at most 256, so the fs bio size won't be bigger than 1M bytes most of times.

Since we support multi-page bvec, in theory one fs bio really can be added > 1M pages, especially in case of hugepage, or big writeback with too many dirty pages. Then there is chance in which .bi_size is overflowed.

Fixes this issue by using bio_full() to check if the added segment may overflow .bi_size.

Any objections to queuing this up for 5.3? It's not a new regression this series.