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Commit 15192b02 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'gfs2-4.11.addendum' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2 

Pull GFS2 fix from Bob Peterson:
 "This is an addendum for the 4.11 merge window.

  Andy Price wrote this patch to close a nasty race condition that
  allows access to glocks that are being destroyed. Without this patch,
  GFS2 is vulnerable to random corruption and kernel panic"

* tag 'gfs2-4.11.addendum' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Add missing rcu locking for glock	lookup
parents 28cbc335 f38e5fb9

fs/gfs2/glock.c

+5 −0
Original line number Diff line number Diff line
@@ -658,9 +658,11 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, 
	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)
@@ -728,15 +730,18 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, 


	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);

	}