[PATCH -next] radi10: fix leak of 'r10bio->remaining' for recovery

From: Yu Kuai
Date: Mon Mar 06 2023 - 21:04:50 EST


From: Yu Kuai <yukuai3@xxxxxxxxxx>

raid10_sync_request() will add 'r10bio->remaining' for both rdev and
replacement rdev. However, if the read io failed,
recovery_request_write() will return without issuring the write io, in
this case, end_sync_request() is only called once and 'remaining' is
leaked, which will cause io hang.

Fix the probleming by decreasing 'remaining' according to if 'bio' and
'repl_bio' is valid.

Fixes: 24afd80d99f8 ("md/raid10: handle recovery of replacement devices.")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/md/raid10.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index a8b5fecef136..f7002a1aa9cf 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2611,11 +2611,22 @@ static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
{
struct r10conf *conf = mddev->private;
int d;
- struct bio *wbio, *wbio2;
+ struct bio *wbio = r10_bio->devs[1].bio;
+ struct bio *wbio2 = r10_bio->devs[1].repl_bio;
+
+ /* Need to test wbio2->bi_end_io before we call
+ * submit_bio_noacct as if the former is NULL,
+ * the latter is free to free wbio2.
+ */
+ if (wbio2 && !wbio2->bi_end_io)
+ wbio2 = NULL;

if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) {
fix_recovery_read_error(r10_bio);
- end_sync_request(r10_bio);
+ if (wbio->bi_end_io)
+ end_sync_request(r10_bio);
+ if (wbio2)
+ end_sync_request(r10_bio);
return;
}

@@ -2624,14 +2635,6 @@ static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
* and submit the write request
*/
d = r10_bio->devs[1].devnum;
- wbio = r10_bio->devs[1].bio;
- wbio2 = r10_bio->devs[1].repl_bio;
- /* Need to test wbio2->bi_end_io before we call
- * submit_bio_noacct as if the former is NULL,
- * the latter is free to free wbio2.
- */
- if (wbio2 && !wbio2->bi_end_io)
- wbio2 = NULL;
if (wbio->bi_end_io) {
atomic_inc(&conf->mirrors[d].rdev->nr_pending);
md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(wbio));
--
2.31.1