[Devel] [PATCH RH8] dm-ploop: Fix detection of unallocated clusters on write

[Kirill Tkhai]

bio_vec may start from bi_idx != 0 and has bi_bvec_done != 0
in case of it was created by bio_split().

https://jira.sw.ru/browse/PSBM-124701
Fixes: 8d9b6a497597 "dm-ploop: Skip zero writes to unallocated clusters"
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 316fd3892f6e..74f9b199d273 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -401,11 +401,15 @@ static bool bio_endio_if_all_zeros(struct bio *bio)
 {
 	struct bvec_iter bi = {
 		.bi_size = bio->bi_iter.bi_size,
+		.bi_bvec_done = bio->bi_iter.bi_bvec_done,
+		.bi_idx = bio->bi_iter.bi_idx,
 	};
 	struct bio_vec bv;
 	void *data, *ret;
 
 	for_each_bvec(bv, bio->bi_io_vec, bi, bi) {
+		if (!bv.bv_len)
+			continue;
 		data = kmap(bv.bv_page);
 		ret = memchr_inv(data + bv.bv_offset, 0, bv.bv_len);
 		kunmap(bv.bv_page);