On 07/14/2017 07:47 AM, Ming Lei wrote: >> @@ -156,6 +156,9 @@ static inline void *bio_data(struct bio *bio) >> /* >> * drivers should _never_ use the all version - the bio may have been split >> * before it got to the driver and the driver won't own all of it >> + * >> + * Note that cloned bios must not use this as their bi_vcnt may be invalid and >> + * this could lead to silent corruptions. >> */ >> #define bio_for_each_segment_all(bvl, bio, i) \ >> for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++) >> -- >> 2.13.0 >> > > Maybe we can add a warning here if it is a cloned bio. I think that's a good idea, it's easy for people to get this wrong, and the consequences can be dire. How about something like this? diff --git a/include/linux/bio.h b/include/linux/bio.h index 7b1cf4ba0902..13b6ac6eae29 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -155,9 +155,12 @@ static inline void *bio_data(struct bio *bio) /* * drivers should _never_ use the all version - the bio may have been split - * before it got to the driver and the driver won't own all of it + * before it got to the driver and the driver won't own all of it. + * + * Don't use this on cloned bio's. */ #define bio_for_each_segment_all(bvl, bio, i) \ + WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)); \ for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++) static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter, -- Jens Axboe
