gfs2: Clear flags when withdraw prevents xmote

There are a couple places in function do_xmote where normal processing
is circumvented due to withdraws in progress. However, since we bypass
most of do_xmote() we bypass telling dlm to lock the dlm lock, which
means dlm will never respond with a completion callback. Since the
completion callback ordinarily clears GLF_LOCK, this patch changes
function do_xmote to handle those situations more gracefully so the
file system may be unmounted after withdraw.

A very similar situation happens with the GLF_DEMOTE_IN_PROGRESS flag,
which is cleared by function finish_xmote(). Since the withdraw causes
us to skip the majority of do_xmote, it therefore also skips the call
to finish_xmote() so the DEMOTE_IN_PROGRESS flag needs to be cleared
manually.

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

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 858616a..dca2cbf 100644 (file)
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -59,6 +59,8 @@ typedef void (*glock_examiner) (struct gfs2_glock * gl);
 
 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
 static void __gfs2_glock_dq(struct gfs2_holder *gh);
+static void handle_callback(struct gfs2_glock *gl, unsigned int state,
+                           unsigned long delay, bool remote);
 
 static struct dentry *gfs2_root;
 static struct workqueue_struct *glock_workqueue;
@@ -730,7 +732,8 @@ static bool is_system_glock(struct gfs2_glock *gl)
  *
  */
 
-static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
+static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh,
+                                        unsigned int target)
 __releases(&gl->gl_lockref.lock)
 __acquires(&gl->gl_lockref.lock)
 {
@@ -741,7 +744,8 @@ __acquires(&gl->gl_lockref.lock)
 
        if (target != LM_ST_UNLOCKED && glock_blocked_by_withdraw(gl) &&
            gh && !(gh->gh_flags & LM_FLAG_NOEXP))
-               return;
+               goto skip_inval;
+
        lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
                      LM_FLAG_PRIORITY);
        GLOCK_BUG_ON(gl, gl->gl_state == target);
@@ -826,6 +830,20 @@ skip_inval:
            (target != LM_ST_UNLOCKED ||
             test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags))) {
                if (!is_system_glock(gl)) {
+                       handle_callback(gl, LM_ST_UNLOCKED, 0, false); /* sets demote */
+                       /*
+                        * Ordinarily, we would call dlm and its callback would call
+                        * finish_xmote, which would call state_change() to the new state.
+                        * Since we withdrew, we won't call dlm, so call state_change
+                        * manually, but to the UNLOCKED state we desire.
+                        */
+                       state_change(gl, LM_ST_UNLOCKED);
+                       /*
+                        * We skip telling dlm to do the locking, so we won't get a
+                        * reply that would otherwise clear GLF_LOCK. So we clear it here.
+                        */
+                       clear_bit(GLF_LOCK, &gl->gl_flags);
+                       clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
                        gfs2_glock_queue_work(gl, GL_GLOCK_DFT_HOLD);
                        goto out;
                } else {