Patch "md/raid10: fix leak of 'r10bio->remaining' for recovery" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    md/raid10: fix leak of 'r10bio->remaining' for recovery

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     md-raid10-fix-leak-of-r10bio-remaining-for-recovery.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 8806a45a2956412e20bae29ee8b3afbbbfeafd16
Author: Yu Kuai <yukuai3@xxxxxxxxxx>
Date:   Fri Mar 10 15:38:53 2023 +0800

    md/raid10: fix leak of 'r10bio->remaining' for recovery
    
    [ Upstream commit 26208a7cffd0c7cbf14237ccd20c7270b3ffeb7e ]
    
    raid10_sync_request() will add 'r10bio->remaining' for both rdev and
    replacement rdev. However, if the read io fails, recovery_request_write()
    returns without issuing the write io, in this case, end_sync_request()
    is only called once and 'remaining' is leaked, cause an io hang.
    
    Fix the problem 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>
    Signed-off-by: Song Liu <song@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230310073855.1337560-5-yukuai1@xxxxxxxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 9f9cd2fadc1e7..8181d9a375f0b 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2266,11 +2266,22 @@ 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
+	 * generic_make_request 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;
 	}
 
@@ -2279,14 +2290,6 @@ 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
-	 * generic_make_request 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));