lockd: handle fl_grant callbacks

Add code to handle file system callback when the lock is finally granted.

Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 87 insertions, 4 deletions

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index f2449265e2eb..6e748573e0c6 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -261,6 +261,7 @@ static void nlmsvc_free_block(struct kref *kref)
         nlmsvc_freegrantargs(block->b_call);
         nlm_release_call(block->b_call);
         nlm_release_file(block->b_file);
+        kfree(block->b_fl);
         kfree(block);
 }
 
@@ -528,6 +529,64 @@ nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
 }
 
 /*
+ * This is a callback from the filesystem for VFS file lock requests.
+ * It will be used if fl_grant is defined and the filesystem can not
+ * respond to the request immediately.
+ * For GETLK request it will copy the reply to the nlm_block.
+ * For SETLK or SETLKW request it will get the local posix lock.
+ * In all cases it will move the block to the head of nlm_blocked q where
+ * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
+ * deferred rpc for GETLK and SETLK.
+ */
+static void
+nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
+                             int result)
+{
+        block->b_flags |= B_GOT_CALLBACK;
+        if (result == 0)
+                block->b_granted = 1;
+        else
+                block->b_flags |= B_TIMED_OUT;
+        if (conf) {
+                block->b_fl = kzalloc(sizeof(struct file_lock), GFP_KERNEL);
+                if (block->b_fl)
+                        locks_copy_lock(block->b_fl, conf);
+        }
+}
+
+static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
+                                        int result)
+{
+        struct nlm_block *block;
+        int rc = -ENOENT;
+
+        lock_kernel();
+        list_for_each_entry(block, &nlm_blocked, b_list) {
+                if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
+                        dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
+                                                        block, block->b_flags);
+                        if (block->b_flags & B_QUEUED) {
+                                if (block->b_flags & B_TIMED_OUT) {
+                                        rc = -ENOLCK;
+                                        break;
+                                }
+                                nlmsvc_update_deferred_block(block, conf, result);
+                        } else if (result == 0)
+                                block->b_granted = 1;
+
+                        nlmsvc_insert_block(block, 0);
+                        svc_wake_up(block->b_daemon);
+                        rc = 0;
+                        break;
+                }
+        }
+        unlock_kernel();
+        if (rc == -ENOENT)
+                printk(KERN_WARNING "lockd: grant for unknown block\n");
+        return rc;
+}
+
+/*
  * Unblock a blocked lock request. This is a callback invoked from the
  * VFS layer when a lock on which we blocked is removed.
  *
@@ -559,6 +618,7 @@ static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 struct lock_manager_operations nlmsvc_lock_operations = {
         .fl_compare_owner = nlmsvc_same_owner,
         .fl_notify = nlmsvc_notify_blocked,
+        .fl_grant = nlmsvc_grant_deferred,
 };
 
 /*
@@ -581,6 +641,8 @@ nlmsvc_grant_blocked(struct nlm_block *block)
 
         dprintk("lockd: grant blocked lock %p\n", block);
 
+        kref_get(&block->b_count);
+
         /* Unlink block request from list */
         nlmsvc_unlink_block(block);
 
@@ -603,11 +665,13 @@ nlmsvc_grant_blocked(struct nlm_block *block)
         case -EAGAIN:
                 dprintk("lockd: lock still blocked\n");
                 nlmsvc_insert_block(block, NLM_NEVER);
+                nlmsvc_release_block(block);
                 return;
         default:
                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
                                 -error, __FUNCTION__);
                 nlmsvc_insert_block(block, 10 * HZ);
+                nlmsvc_release_block(block);
                 return;
         }
 
@@ -620,7 +684,6 @@ callback:
         nlmsvc_insert_block(block, 30 * HZ);
 
         /* Call the client */
-        kref_get(&block->b_count);
         nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, &nlmsvc_grant_ops);
 }
 
@@ -693,6 +756,23 @@ nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
         nlmsvc_release_block(block);
 }
 
+/* Helper function to handle retry of a deferred block.
+ * If it is a blocking lock, call grant_blocked.
+ * For a non-blocking lock or test lock, revisit the request.
+ */
+static void
+retry_deferred_block(struct nlm_block *block)
+{
+        if (!(block->b_flags & B_GOT_CALLBACK))
+                block->b_flags |= B_TIMED_OUT;
+        nlmsvc_insert_block(block, NLM_TIMEOUT);
+        dprintk("revisit block %p flags %d\n",  block, block->b_flags);
+        if (block->b_deferred_req) {
+                block->b_deferred_req->revisit(block->b_deferred_req, 0);
+                block->b_deferred_req = NULL;
+        }
+}
+
 /*
  * Retry all blocked locks that have been notified. This is where lockd
  * picks up locks that can be granted, or grant notifications that must
@@ -716,9 +796,12 @@ nlmsvc_retry_blocked(void)
 
                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
                         block, block->b_when);
-                kref_get(&block->b_count);
-                nlmsvc_grant_blocked(block);
-                nlmsvc_release_block(block);
+                if (block->b_flags & B_QUEUED) {
+                        dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
+                                block, block->b_granted, block->b_flags);
+                        retry_deferred_block(block);
+                } else
+                        nlmsvc_grant_blocked(block);
         }
 
         return timeout;