2 files changed, 75 insertions, 18 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 17903b491298..031dbe3a15ca 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -733,10 +733,7 @@ static void lkb_add_ordered(struct list_head *new, struct list_head *head,
                 if (lkb->lkb_rqmode < mode)
                         break;
 
-        if (!lkb)
-                list_add_tail(new, head);
-        else
-                __list_add(new, lkb->lkb_statequeue.prev, &lkb->lkb_statequeue);
+        __list_add(new, lkb->lkb_statequeue.prev, &lkb->lkb_statequeue);
 }
 
 /* add/remove lkb to rsb's grant/convert/wait queue */
diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 8b6e73c47435..b6272853130c 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -215,6 +215,7 @@ void dlm_user_add_ast(struct dlm_lkb *lkb, int type, int mode)
         if (!ast_type) {
                 kref_get(&lkb->lkb_ref);
                 list_add_tail(&lkb->lkb_astqueue, &proc->asts);
+                lkb->lkb_ast_first = type;
                 wake_up_interruptible(&proc->wait);
         }
         if (type == AST_COMP && (ast_type & AST_COMP))
@@ -223,7 +224,6 @@ void dlm_user_add_ast(struct dlm_lkb *lkb, int type, int mode)
 
         eol = lkb_is_endoflife(lkb, ua->lksb.sb_status, type);
         if (eol) {
-                lkb->lkb_ast_type &= ~AST_BAST;
                 lkb->lkb_flags |= DLM_IFL_ENDOFLIFE;
         }
 
@@ -706,7 +706,7 @@ static int device_close(struct inode *inode, struct file *file)
 }
 
 static int copy_result_to_user(struct dlm_user_args *ua, int compat, int type,
-                               int bmode, char __user *buf, size_t count)
+                               int mode, char __user *buf, size_t count)
 {
 #ifdef CONFIG_COMPAT
         struct dlm_lock_result32 result32;
@@ -733,7 +733,7 @@ static int copy_result_to_user(struct dlm_user_args *ua, int compat, int type,
         if (type == AST_BAST) {
                 result.user_astaddr = ua->bastaddr;
                 result.user_astparam = ua->bastparam;
-                result.bast_mode = bmode;
+                result.bast_mode = mode;
         } else {
                 result.user_astaddr = ua->castaddr;
                 result.user_astparam = ua->castparam;
@@ -801,7 +801,9 @@ static ssize_t device_read(struct file *file, char __user *buf, size_t count,
         struct dlm_user_proc *proc = file->private_data;
         struct dlm_lkb *lkb;
         DECLARE_WAITQUEUE(wait, current);
-        int error, type=0, bmode=0, removed = 0;
+        int error = 0, removed;
+        int ret_type, ret_mode;
+        int bastmode, castmode, do_bast, do_cast;
 
         if (count == sizeof(struct dlm_device_version)) {
                 error = copy_version_to_user(buf, count);
@@ -820,6 +822,8 @@ static ssize_t device_read(struct file *file, char __user *buf, size_t count,
 #endif
                 return -EINVAL;
 
+ try_another:
+
         /* do we really need this? can a read happen after a close? */
         if (test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
                 return -EINVAL;
@@ -855,13 +859,55 @@ static ssize_t device_read(struct file *file, char __user *buf, size_t count,
 
         lkb = list_entry(proc->asts.next, struct dlm_lkb, lkb_astqueue);
 
-        if (lkb->lkb_ast_type & AST_COMP) {
-                lkb->lkb_ast_type &= ~AST_COMP;
-                type = AST_COMP;
-        } else if (lkb->lkb_ast_type & AST_BAST) {
-                lkb->lkb_ast_type &= ~AST_BAST;
-                type = AST_BAST;
-                bmode = lkb->lkb_bastmode;
+        removed = 0;
+        ret_type = 0;
+        ret_mode = 0;
+        do_bast = lkb->lkb_ast_type & AST_BAST;
+        do_cast = lkb->lkb_ast_type & AST_COMP;
+        bastmode = lkb->lkb_bastmode;
+        castmode = lkb->lkb_castmode;
+
+        /* when both are queued figure out which to do first and
+           switch first so the other goes in the next read */
+
+        if (do_cast && do_bast) {
+                if (lkb->lkb_ast_first == AST_COMP) {
+                        ret_type = AST_COMP;
+                        ret_mode = castmode;
+                        lkb->lkb_ast_type &= ~AST_COMP;
+                        lkb->lkb_ast_first = AST_BAST;
+                } else {
+                        ret_type = AST_BAST;
+                        ret_mode = bastmode;
+                        lkb->lkb_ast_type &= ~AST_BAST;
+                        lkb->lkb_ast_first = AST_COMP;
+                }
+        } else {
+                ret_type = lkb->lkb_ast_first;
+                ret_mode = (ret_type == AST_COMP) ? castmode : bastmode;
+                lkb->lkb_ast_type &= ~ret_type;
+                lkb->lkb_ast_first = 0;
+        }
+
+        /* if we're doing a bast but the bast is unnecessary, then
+           switch to do nothing or do a cast if that was needed next */
+
+        if ((ret_type == AST_BAST) &&
+            dlm_modes_compat(bastmode, lkb->lkb_castmode_done)) {
+                ret_type = 0;
+                ret_mode = 0;
+
+                if (do_cast) {
+                        ret_type = AST_COMP;
+                        ret_mode = castmode;
+                        lkb->lkb_ast_type &= ~AST_COMP;
+                        lkb->lkb_ast_first = 0;
+                }
+        }
+
+        if (lkb->lkb_ast_first != lkb->lkb_ast_type) {
+                log_print("device_read %x ast_first %x ast_type %x",
+                          lkb->lkb_id, lkb->lkb_ast_first, lkb->lkb_ast_type);
         }
 
         if (!lkb->lkb_ast_type) {
@@ -870,15 +916,29 @@ static ssize_t device_read(struct file *file, char __user *buf, size_t count,
         }
         spin_unlock(&proc->asts_spin);
 
-        error = copy_result_to_user(lkb->lkb_ua,
-                                test_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags),
-                                type, bmode, buf, count);
+        if (ret_type) {
+                error = copy_result_to_user(lkb->lkb_ua,
+                                test_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags),
+                                ret_type, ret_mode, buf, count);
+
+                if (ret_type == AST_COMP)
+                        lkb->lkb_castmode_done = castmode;
+                if (ret_type == AST_BAST)
+                        lkb->lkb_bastmode_done = bastmode;
+        }
 
         /* removes reference for the proc->asts lists added by
            dlm_user_add_ast() and may result in the lkb being freed */
+
         if (removed)
                 dlm_put_lkb(lkb);
 
+        /* the bast that was queued was eliminated (see unnecessary above),
+           leaving nothing to return */
+
+        if (!ret_type)
+                goto try_another;
+
         return error;
 }