linux-kernel - [PATCH 5.17 0813/1126] NFS: Dont loop forever in nfs_do

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Date:   Tue,  5 Apr 2022 09:26:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Olga Kornievskaia <aglo@...ch.edu>,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.17 0813/1126] NFS: Dont loop forever in nfs_do_recoalesce()

From: Trond Myklebust <trond.myklebust@...merspace.com>

[ Upstream commit d02d81efc7564b4d5446a02e0214a164cf00b1f3 ]

If __nfs_pageio_add_request() fails to add the request, it will return
with either desc->pg_error < 0, or mirror->pg_recoalesce will be set, so
we are guaranteed either to exit the function altogether, or to loop.

However if there is nothing left in mirror->pg_list to coalesce, we must
exit, so make sure that we clear mirror->pg_recoalesce every time we
loop.

Reported-by: Olga Kornievskaia <aglo@...ch.edu>
Fixes: 70536bf4eb07 ("NFS: Clean up reset of the mirror accounting variables")
Signed-off-by: Trond Myklebust <trond.myklebust@...merspace.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/nfs/pagelist.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index ad7f83dc9a2d..815d63080245 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -1218,6 +1218,7 @@ static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
 
 	do {
 		list_splice_init(&mirror->pg_list, &head);
+		mirror->pg_recoalesce = 0;
 
 		while (!list_empty(&head)) {
 			struct nfs_page *req;
-- 
2.34.1