Revert "gfs2: Don't demote a glock until its revokes are written"

This reverts commit fff88dbab14ed753a4b5a8eb15050c09e46a7109.

This patch fixes a regression: patch fff88dbab14ed allowed function
run_queue() to bypass its call to do_xmote() if revokes were queued for
the glock. That's wrong because its call to do_xmote() is what is
responsible for calling the go_sync() glops functions to sync both
the ail list and any revokes queued for it. By bypassing the call,
gfs2 could get into a stand-off where the glock could not be demoted
until its revokes are written back, but the revokes would not be
written back because do_xmote() was never called.

It "sort of" works, however, because there are other mechanisms like
the log flush daemon (logd) that can sync the ail items and revokes,
if it deems it necessary. The problem is: without file system pressure,
it might never deem it necessary.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 5239098fcce60f3afd443dc3572309af4bb60562..bf70e3b14938e0698557c44ba414078f8f6b986e 100644 (file)
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -723,9 +723,6 @@ __acquires(&gl->gl_lockref.lock)
                        goto out_unlock;
                if (nonblock)
                        goto out_sched;
-               smp_mb();
-               if (atomic_read(&gl->gl_revokes) != 0)
-                       goto out_sched;
                set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
                GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
                gl->gl_target = gl->gl_demote_state;