From: Andreas Gruenbacher agruenba@redhat.com
[ Upstream commit 7427f3bb49d81525b7dd1d0f7c5f6bbc752e6f0e ]
So far, glock_hash_walk took a reference on each glock it iterated over, and it was the examiner's responsibility to drop those references. Dropping the final reference to a glock can sleep and the examiners are called in a RCU critical section with spin locks held, so examiners that didn't need the extra reference had to drop it asynchronously via gfs2_glock_queue_put or similar. This wasn't done correctly in thaw_glock which did call gfs2_glock_put, and not at all in dump_glock_func.
Change glock_hash_walk to not take glock references at all. That way, the examiners that don't need them won't have to bother with slow asynchronous puts, and the examiners that do need references can take them themselves.
Reported-by: Alexander Aring aahringo@redhat.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/gfs2/glock.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index fea68ed127b89..b17b6350c0317 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1894,10 +1894,10 @@ static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp) do { rhashtable_walk_start(&iter);
- while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) - if (gl->gl_name.ln_sbd == sdp && - lockref_get_not_dead(&gl->gl_lockref)) + while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) { + if (gl->gl_name.ln_sbd == sdp) examiner(gl); + }
rhashtable_walk_stop(&iter); } while (cond_resched(), gl == ERR_PTR(-EAGAIN)); @@ -1939,7 +1939,6 @@ static void flush_delete_work(struct gfs2_glock *gl) &gl->gl_delete, 0); } } - gfs2_glock_queue_work(gl, 0); }
void gfs2_flush_delete_work(struct gfs2_sbd *sdp) @@ -1956,10 +1955,10 @@ void gfs2_flush_delete_work(struct gfs2_sbd *sdp)
static void thaw_glock(struct gfs2_glock *gl) { - if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) { - gfs2_glock_put(gl); + if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) + return; + if (!lockref_get_not_dead(&gl->gl_lockref)) return; - } set_bit(GLF_REPLY_PENDING, &gl->gl_flags); gfs2_glock_queue_work(gl, 0); } @@ -1975,9 +1974,12 @@ static void clear_glock(struct gfs2_glock *gl) gfs2_glock_remove_from_lru(gl);
spin_lock(&gl->gl_lockref.lock); - if (gl->gl_state != LM_ST_UNLOCKED) - handle_callback(gl, LM_ST_UNLOCKED, 0, false); - __gfs2_glock_queue_work(gl, 0); + if (!__lockref_is_dead(&gl->gl_lockref)) { + gl->gl_lockref.count++; + if (gl->gl_state != LM_ST_UNLOCKED) + handle_callback(gl, LM_ST_UNLOCKED, 0, false); + __gfs2_glock_queue_work(gl, 0); + } spin_unlock(&gl->gl_lockref.lock); }