NFS: Clean up nfs_sb_active/nfs_sb_deactive

Instead of causing umount requests to block on server->active_wq while the
asynchronous sillyrename deletes are executing, we can use the sb->s_active
counter to obtain a reference to the super_block, and then release that
reference in nfs_async_unlink_release().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

5 files changed, 13 insertions, 22 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 5ee23e7058b3..2accb67427c6 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -850,7 +850,6 @@ static struct nfs_server *nfs_alloc_server(void)
         INIT_LIST_HEAD(&server->client_link);
         INIT_LIST_HEAD(&server->master_link);
 
-        init_waitqueue_head(&server->active_wq);
         atomic_set(&server->active, 0);
 
         server->io_stats = nfs_alloc_iostats();
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 24241fcbb98d..7bcf6ec2d458 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -163,8 +163,8 @@ extern struct rpc_stat nfs_rpcstat;
 
 extern int __init register_nfs_fs(void);
 extern void __exit unregister_nfs_fs(void);
-extern void nfs_sb_active(struct nfs_server *server);
-extern void nfs_sb_deactive(struct nfs_server *server);
+extern void nfs_sb_active(struct super_block *sb);
+extern void nfs_sb_deactive(struct super_block *sb);
 
 /* namespace.c */
 extern char *nfs_path(const char *base,
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index e9b20173fef3..e527fab40419 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -209,7 +209,6 @@ static int nfs_get_sb(struct file_system_type *, int, const char *, void *, stru
 static int nfs_xdev_get_sb(struct file_system_type *fs_type,
                 int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
 static void nfs_kill_super(struct super_block *);
-static void nfs_put_super(struct super_block *);
 static int nfs_remount(struct super_block *sb, int *flags, char *raw_data);
 
 static struct file_system_type nfs_fs_type = {
@@ -232,7 +231,6 @@ static const struct super_operations nfs_sops = {
         .alloc_inode    = nfs_alloc_inode,
         .destroy_inode  = nfs_destroy_inode,
         .write_inode    = nfs_write_inode,
-        .put_super      = nfs_put_super,
         .statfs         = nfs_statfs,
         .clear_inode    = nfs_clear_inode,
         .umount_begin   = nfs_umount_begin,
@@ -337,26 +335,20 @@ void __exit unregister_nfs_fs(void)
         unregister_filesystem(&nfs_fs_type);
 }
 
-void nfs_sb_active(struct nfs_server *server)
+void nfs_sb_active(struct super_block *sb)
 {
-        atomic_inc(&server->active);
-}
+        struct nfs_server *server = NFS_SB(sb);
 
-void nfs_sb_deactive(struct nfs_server *server)
-{
-        if (atomic_dec_and_test(&server->active))
-                wake_up(&server->active_wq);
+        if (atomic_inc_return(&server->active) == 1)
+                atomic_inc(&sb->s_active);
 }
 
-static void nfs_put_super(struct super_block *sb)
+void nfs_sb_deactive(struct super_block *sb)
 {
         struct nfs_server *server = NFS_SB(sb);
-        /*
-         * Make sure there are no outstanding ops to this server.
-         * If so, wait for them to finish before allowing the
-         * unmount to continue.
-         */
-        wait_event(server->active_wq, atomic_read(&server->active) == 0);
+
+        if (atomic_dec_and_test(&server->active))
+                deactivate_super(sb);
 }
 
 /*
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index f089e5839d7d..ecc295347775 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -99,7 +99,7 @@ static void nfs_async_unlink_release(void *calldata)
 
         nfs_dec_sillycount(data->dir);
         nfs_free_unlinkdata(data);
-        nfs_sb_deactive(NFS_SB(sb));
+        nfs_sb_deactive(sb);
 }
 
 static const struct rpc_call_ops nfs_unlink_ops = {
@@ -118,6 +118,7 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
                 .rpc_message = &msg,
                 .callback_ops = &nfs_unlink_ops,
                 .callback_data = data,
+                .workqueue = nfsiod_workqueue,
                 .flags = RPC_TASK_ASYNC,
         };
         struct rpc_task *task;
@@ -149,7 +150,7 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
                 nfs_dec_sillycount(dir);
                 return 0;
         }
-        nfs_sb_active(NFS_SERVER(dir));
+        nfs_sb_active(dir->i_sb);
         data->args.fh = NFS_FH(dir);
         nfs_fattr_init(&data->res.dir_attr);
 
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index c9beacd16c00..4e477ae58699 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -119,7 +119,6 @@ struct nfs_server {
         void (*destroy)(struct nfs_server *);
 
         atomic_t active; /* Keep trace of any activity to this server */
-        wait_queue_head_t active_wq;  /* Wait for any activity to stop  */
 
         /* mountd-related mount options */
         struct sockaddr_storage mountd_address;