1 files changed, 80 insertions, 2 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index eac54d230fdc..d8d6e729f96b 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -224,6 +224,16 @@ static inline int is_demoted(struct dlm_lkb *lkb)
         return (lkb->lkb_sbflags & DLM_SBF_DEMOTED);
 }
 
+static inline int is_altmode(struct dlm_lkb *lkb)
+{
+        return (lkb->lkb_sbflags & DLM_SBF_ALTMODE);
+}
+
+static inline int is_granted(struct dlm_lkb *lkb)
+{
+        return (lkb->lkb_status == DLM_LKSTS_GRANTED);
+}
+
 static inline int is_remote(struct dlm_rsb *r)
 {
         DLM_ASSERT(r->res_nodeid >= 0, dlm_print_rsb(r););
@@ -1191,6 +1201,50 @@ static void grant_lock_pending(struct dlm_rsb *r, struct dlm_lkb *lkb)
                 queue_cast(r, lkb, 0);
 }
 
+/* The special CONVDEADLK, ALTPR and ALTCW flags allow the master to
+   change the granted/requested modes.  We're munging things accordingly in
+   the process copy.
+   CONVDEADLK: our grmode may have been forced down to NL to resolve a
+   conversion deadlock
+   ALTPR/ALTCW: our rqmode may have been changed to PR or CW to become
+   compatible with other granted locks */
+
+static void munge_demoted(struct dlm_lkb *lkb, struct dlm_message *ms)
+{
+        if (ms->m_type != DLM_MSG_CONVERT_REPLY) {
+                log_print("munge_demoted %x invalid reply type %d",
+                          lkb->lkb_id, ms->m_type);
+                return;
+        }
+
+        if (lkb->lkb_rqmode == DLM_LOCK_IV || lkb->lkb_grmode == DLM_LOCK_IV) {
+                log_print("munge_demoted %x invalid modes gr %d rq %d",
+                          lkb->lkb_id, lkb->lkb_grmode, lkb->lkb_rqmode);
+                return;
+        }
+
+        lkb->lkb_grmode = DLM_LOCK_NL;
+}
+
+static void munge_altmode(struct dlm_lkb *lkb, struct dlm_message *ms)
+{
+        if (ms->m_type != DLM_MSG_REQUEST_REPLY &&
+            ms->m_type != DLM_MSG_GRANT) {
+                log_print("munge_altmode %x invalid reply type %d",
+                          lkb->lkb_id, ms->m_type);
+                return;
+        }
+
+        if (lkb->lkb_exflags & DLM_LKF_ALTPR)
+                lkb->lkb_rqmode = DLM_LOCK_PR;
+        else if (lkb->lkb_exflags & DLM_LKF_ALTCW)
+                lkb->lkb_rqmode = DLM_LOCK_CW;
+        else {
+                log_print("munge_altmode invalid exflags %x", lkb->lkb_exflags);
+                dlm_print_lkb(lkb);
+        }
+}
+
 static inline int first_in_list(struct dlm_lkb *lkb, struct list_head *head)
 {
         struct dlm_lkb *first = list_entry(head->next, struct dlm_lkb,
@@ -1965,9 +2019,24 @@ static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
                 goto out;
         }
 
-        if (can_be_queued(lkb)) {
-                if (is_demoted(lkb))
+        /* is_demoted() means the can_be_granted() above set the grmode
+           to NL, and left us on the granted queue.  This auto-demotion
+           (due to CONVDEADLK) might mean other locks, and/or this lock, are
+           now grantable.  We have to try to grant other converting locks
+           before we try again to grant this one. */
+
+        if (is_demoted(lkb)) {
+                grant_pending_convert(r, DLM_LOCK_IV);
+                if (_can_be_granted(r, lkb, 1)) {
+                        grant_lock(r, lkb);
+                        queue_cast(r, lkb, 0);
                         grant_pending_locks(r);
+                        goto out;
+                }
+                /* else fall through and move to convert queue */
+        }
+
+        if (can_be_queued(lkb)) {
                 error = -EINPROGRESS;
                 del_lkb(r, lkb);
                 add_lkb(r, lkb, DLM_LKSTS_CONVERT);
@@ -2908,6 +2977,8 @@ static void receive_grant(struct dlm_ls *ls, struct dlm_message *ms)
         lock_rsb(r);
 
         receive_flags_reply(lkb, ms);
+        if (is_altmode(lkb))
+                munge_altmode(lkb, ms);
         grant_lock_pc(r, lkb, ms);
         queue_cast(r, lkb, 0);
 
@@ -3038,6 +3109,8 @@ static void receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
                 /* request was queued or granted on remote master */
                 receive_flags_reply(lkb, ms);
                 lkb->lkb_remid = ms->m_lkid;
+                if (is_altmode(lkb))
+                        munge_altmode(lkb, ms);
                 if (result)
                         add_lkb(r, lkb, DLM_LKSTS_WAITING);
                 else {
@@ -3101,6 +3174,9 @@ static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
 
         case -EINPROGRESS:
                 /* convert was queued on remote master */
+                receive_flags_reply(lkb, ms);
+                if (is_demoted(lkb))
+                        munge_demoted(lkb, ms);
                 del_lkb(r, lkb);
                 add_lkb(r, lkb, DLM_LKSTS_CONVERT);
                 break;
@@ -3108,6 +3184,8 @@ static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
         case 0:
                 /* convert was granted on remote master */
                 receive_flags_reply(lkb, ms);
+                if (is_demoted(lkb))
+                        munge_demoted(lkb, ms);
                 grant_lock_pc(r, lkb, ms);
                 queue_cast(r, lkb, 0);
                 break;