The commit is pushed to "branch-rh9-5.14.0-427.44.1.vz9.80.x-ovz" and will
appear at g...@bitbucket.org:openvz/vzkernel.git
after rh9-5.14.0-427.44.1.vz9.80.3
------>
commit f879e056c4a69cb57e6fe6ae1edc091ebc2982c2
Author: Alexander Atanasov <alexander.atana...@virtuozzo.com>
Date: Tue Dec 17 12:34:44 2024 +0200
dm-qcow2: only use inline bvec if iteration is valid
In some cases qcow2 is passed requests without bvec set and
zero bi_size - for such requests qcow2 resorts to inline bvecs
which in that case are invalid.
To address this:
- Check if bi_size is not zero, and only then use the inline bvecs.
- Properly count number of segments in a NULL bvec.
- Add warn on to catch if we have a request with NULL bvec and
non-zero bi_size.
https://virtuozzo.atlassian.net/browse/PSBM-159903
Signed-off-by: Alexander Atanasov <alexander.atana...@virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com>
Feature: dm-qcow2: block device over QCOW2 files driver
khorenko@: so after that patch in prepare_one_embedded_qio() we may have
qio->bi_io_vec = bvec = NULL in case !bvec && !rq->bio->bi_iter.bi_size,
but such requests (these are control requests, discards for example)
should not get into __submit_rw_mapped(), thus the WARN_ON() is there.
---
drivers/md/dm-qcow2-map.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c
index 112f6dde44af..54bb8bd713be 100644
--- a/drivers/md/dm-qcow2-map.c
+++ b/drivers/md/dm-qcow2-map.c
@@ -308,6 +308,9 @@ static unsigned int qio_nr_segs(struct qio *qio)
struct bvec_iter iter;
struct bio_vec bv;
+ if (!qio->bi_io_vec)
+ return 0;
+
qcow2_for_each_bvec(iter, bv, qio->bi_iter, qio->bi_io_vec)
nr_segs++;
@@ -1248,6 +1251,7 @@ static void __submit_rw_mapped(struct qcow2 *qcow2,
struct qio *qio, u32 nr_segs
bvec = __bvec_iter_bvec(qio->bi_io_vec, qio->bi_iter);
pos = to_bytes(qio->bi_iter.bi_sector);
+ WARN_ON(qio->bi_iter.bi_size && !bvec);
iov_iter_bvec(&iter, rw, bvec, nr_segs, qio->bi_iter.bi_size);
iter.iov_offset = qio->bi_iter.bi_bvec_done;
@@ -3538,7 +3542,7 @@ static void prepare_one_embedded_qio(struct qcow2 *qcow2,
struct qio *qio,
} else {
/* Single bio already provides bvec array */
bvec = rq->bio->bi_io_vec;
- if (!bvec) {
+ if (!bvec && rq->bio->bi_iter.bi_size) {
bvec = rq->bio->bi_inline_vecs;
if (unlikely(!bvec)) {
QC_ERR(qcow2->tgt->ti, "Expecting inline bvec");
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