linux-kernel - [PATCH 4.4 02/64] gfs2: Wake up when sd_glock

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Message-Id: <20201117122106.250567431@linuxfoundation.org>
Date:   Tue, 17 Nov 2020 14:04:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexander Aring <aahringo@...hat.com>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 02/64] gfs2: Wake up when sd_glock_disposal becomes zero

From: Alexander Aring <aahringo@...hat.com>

[ Upstream commit da7d554f7c62d0c17c1ac3cc2586473c2d99f0bd ]

Commit fc0e38dae645 ("GFS2: Fix glock deallocation race") fixed a
sd_glock_disposal accounting bug by adding a missing atomic_dec
statement, but it failed to wake up sd_glock_wait when that decrement
causes sd_glock_disposal to reach zero.  As a consequence,
gfs2_gl_hash_clear can now run into a 10-minute timeout instead of
being woken up.  Add the missing wakeup.

Fixes: fc0e38dae645 ("GFS2: Fix glock deallocation race")
Cc: stable@...r.kernel.org # v2.6.39+
Signed-off-by: Alexander Aring <aahringo@...hat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/gfs2/glock.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 1eb737c466ddc..8e8695eb652af 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -751,7 +751,8 @@ again:
 	}
 	kfree(gl->gl_lksb.sb_lvbptr);
 	kmem_cache_free(cachep, gl);
-	atomic_dec(&sdp->sd_glock_disposal);
+	if (atomic_dec_and_test(&sdp->sd_glock_disposal))
+		wake_up(&sdp->sd_glock_wait);
 	*glp = tmp;
 
 	return ret;
-- 
2.27.0