From 4043b886b0740ded65f633fc4b7225d624c7e658 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Mon, 16 Jan 2012 15:46:21 +0000 Subject: GFS2: Fix race between lru_list and glock ref count This patch fixes a narrow race window between the glock ref count hitting zero and glocks being removed from the lru_list. Signed-off-by: Steven Whitehouse --- fs/gfs2/glock.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'fs') diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 376816fcd040..351a3e797789 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -167,14 +167,19 @@ void gfs2_glock_add_to_lru(struct gfs2_glock *gl) spin_unlock(&lru_lock); } -static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl) +static void __gfs2_glock_remove_from_lru(struct gfs2_glock *gl) { - spin_lock(&lru_lock); if (!list_empty(&gl->gl_lru)) { list_del_init(&gl->gl_lru); atomic_dec(&lru_count); clear_bit(GLF_LRU, &gl->gl_flags); } +} + +static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl) +{ + spin_lock(&lru_lock); + __gfs2_glock_remove_from_lru(gl); spin_unlock(&lru_lock); } @@ -217,11 +222,12 @@ void gfs2_glock_put(struct gfs2_glock *gl) struct gfs2_sbd *sdp = gl->gl_sbd; struct address_space *mapping = gfs2_glock2aspace(gl); - if (atomic_dec_and_test(&gl->gl_ref)) { + if (atomic_dec_and_lock(&gl->gl_ref, &lru_lock)) { + __gfs2_glock_remove_from_lru(gl); + spin_unlock(&lru_lock); spin_lock_bucket(gl->gl_hash); hlist_bl_del_rcu(&gl->gl_list); spin_unlock_bucket(gl->gl_hash); - gfs2_glock_remove_from_lru(gl); GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders)); GLOCK_BUG_ON(gl, mapping && mapping->nrpages); trace_gfs2_glock_put(gl); -- cgit v1.2.3