From: Sweet Tea sweettea@redhat.com
[ Upstream commit a00f5276e26636cbf72f24f79831026d2e2868e7 ]
The flakey target is documented to be able to corrupt the Nth byte in a bio, but does not corrupt byte indices after the first biovec in the bio. Change the corrupting function to actually corrupt the Nth byte no matter in which biovec that index falls.
A test device generating two-page bios, atop a flakey device configured to corrupt a byte index on the second page, verified both the failure to corrupt before this patch and the expected corruption after this change.
Signed-off-by: John Dorminy jdorminy@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-flakey.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-)
diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c index b86d2439ffc76..2fcf62fb2844f 100644 --- a/drivers/md/dm-flakey.c +++ b/drivers/md/dm-flakey.c @@ -287,20 +287,31 @@ static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc) { - unsigned bio_bytes = bio_cur_bytes(bio); - char *data = bio_data(bio); + unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1; + + struct bvec_iter iter; + struct bio_vec bvec; + + if (!bio_has_data(bio)) + return;
/* - * Overwrite the Nth byte of the data returned. + * Overwrite the Nth byte of the bio's data, on whichever page + * it falls. */ - if (data && bio_bytes >= fc->corrupt_bio_byte) { - data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value; - - DMDEBUG("Corrupting data bio=%p by writing %u to byte %u " - "(rw=%c bi_opf=%u bi_sector=%llu cur_bytes=%u)\n", - bio, fc->corrupt_bio_value, fc->corrupt_bio_byte, - (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf, - (unsigned long long)bio->bi_iter.bi_sector, bio_bytes); + bio_for_each_segment(bvec, bio, iter) { + if (bio_iter_len(bio, iter) > corrupt_bio_byte) { + char *segment = (page_address(bio_iter_page(bio, iter)) + + bio_iter_offset(bio, iter)); + segment[corrupt_bio_byte] = fc->corrupt_bio_value; + DMDEBUG("Corrupting data bio=%p by writing %u to byte %u " + "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n", + bio, fc->corrupt_bio_value, fc->corrupt_bio_byte, + (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf, + (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size); + break; + } + corrupt_bio_byte -= bio_iter_len(bio, iter); } }