This is a note to let you know that I've just added the patch titled
gfs2: Add missing rcu locking for glock lookup
to the 4.4-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:
gfs2-add-missing-rcu-locking-for-glock-lookup.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f38e5fb95a1f8feda88531eedc98f69b24748712 Mon Sep 17 00:00:00 2001
From: Andrew Price <anprice@xxxxxxxxxx>
Date: Wed, 22 Feb 2017 12:05:03 -0500
Subject: gfs2: Add missing rcu locking for glock lookup
From: Andrew Price <anprice@xxxxxxxxxx>
commit f38e5fb95a1f8feda88531eedc98f69b24748712 upstream.
We must hold the rcu read lock across looking up glocks and trying to
bump their refcount to prevent the glocks from being freed in between.
Signed-off-by: Andrew Price <anprice@xxxxxxxxxx>
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Bob Peterson <rpeterso@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/gfs2/glock.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -651,9 +651,11 @@ int gfs2_glock_get(struct gfs2_sbd *sdp,
struct kmem_cache *cachep;
int ret, tries = 0;
+ rcu_read_lock();
gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
if (gl && !lockref_get_not_dead(&gl->gl_lockref))
gl = NULL;
+ rcu_read_unlock();
*glp = gl;
if (gl)
@@ -721,15 +723,18 @@ again:
if (ret == -EEXIST) {
ret = 0;
+ rcu_read_lock();
tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) {
if (++tries < 100) {
+ rcu_read_unlock();
cond_resched();
goto again;
}
tmp = NULL;
ret = -ENOMEM;
}
+ rcu_read_unlock();
} else {
WARN_ON_ONCE(ret);
}
Patches currently in stable-queue which might be from anprice@xxxxxxxxxx are
queue-4.4/gfs2-add-missing-rcu-locking-for-glock-lookup.patch