From 85a8ce62c2eabe28b9d76ca4eecf37922402df93 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 28 Dec 2019 07:05:48 +0800 Subject: block: add bio_truncate to fix guard_bio_eod Some filesystem, such as vfat, may send bio which crosses device boundary, and the worse thing is that the IO request starting within device boundaries can contain more than one segment past EOD. Commit dce30ca9e3b6 ("fs: fix guard_bio_eod to check for real EOD errors") tries to fix this issue by returning -EIO for this situation. However, this way lets fs user code lose chance to handle -EIO, then sync_inodes_sb() may hang for ever. Also the current truncating on last segment is dangerous by updating the last bvec, given bvec table becomes not immutable any more, and fs bio users may not retrieve the truncated pages via bio_for_each_segment_all() in its .end_io callback. Fixes this issue by supporting multi-segment truncating. And the approach is simpler: - just update bio size since block layer can make correct bvec with the updated bio size. Then bvec table becomes really immutable. - zero all truncated segments for read bio Cc: Carlos Maiolino Cc: linux-fsdevel@vger.kernel.org Fixed-by: dce30ca9e3b6 ("fs: fix guard_bio_eod to check for real EOD errors") Reported-by: syzbot+2b9e54155c8c25d8d165@syzkaller.appspotmail.com Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- include/linux/bio.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/bio.h b/include/linux/bio.h index 3cdb84cdc488..853d92ceee64 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -470,6 +470,7 @@ extern struct bio *bio_copy_user_iov(struct request_queue *, gfp_t); extern int bio_uncopy_user(struct bio *); void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter); +void bio_truncate(struct bio *bio, unsigned new_size); static inline void zero_fill_bio(struct bio *bio) { -- cgit v1.2.3