NFS: Stop sillyname renames and unmounts from racing

Added an active/deactive mechanism to the nfs_server structure
allowing async operations to hold off umount until the
operations are done.

Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index a6f6254..c3740f5 100644 (file)
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -729,6 +729,9 @@ 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();
        if (!server->io_stats) {
                kfree(server);

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index f3acf48..7579379 100644 (file)
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -160,6 +160,8 @@ 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);
 
 /* namespace.c */
 extern char *nfs_path(const char *base,

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 0b0c72a..fda1635 100644 (file)
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -202,6 +202,7 @@ 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 struct file_system_type nfs_fs_type = {
        .owner          = THIS_MODULE,
@@ -223,6 +224,7 @@ 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,
@@ -325,6 +327,28 @@ void __exit unregister_nfs_fs(void)
        unregister_filesystem(&nfs_fs_type);
 }
 
+void nfs_sb_active(struct nfs_server *server)
+{
+       atomic_inc(&server->active);
+}
+
+void nfs_sb_deactive(struct nfs_server *server)
+{
+       if (atomic_dec_and_test(&server->active))
+               wake_up(&server->active_wq);
+}
+
+static void nfs_put_super(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);
+}
+
 /*
  * Deliver file system statistics to userspace
  */

diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 431981d..8e5428e 100644 (file)
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -14,6 +14,8 @@
 #include <linux/sched.h>
 #include <linux/wait.h>
 
+#include "internal.h"
+
 struct nfs_unlinkdata {
        struct hlist_node list;
        struct nfs_removeargs args;
@@ -113,6 +115,7 @@ static void nfs_async_unlink_release(void *calldata)
        struct nfs_unlinkdata   *data = calldata;
 
        nfs_dec_sillycount(data->dir);
+       nfs_sb_deactive(NFS_SERVER(data->dir));
        nfs_free_unlinkdata(data);
 }
 
@@ -153,6 +156,7 @@ 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));
        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 0cac49b..9f949b5 100644 (file)
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -3,6 +3,9 @@
 
 #include <linux/list.h>
 #include <linux/backing-dev.h>
+#include <linux/wait.h>
+
+#include <asm/atomic.h>
 
 struct nfs_iostats;
 
@@ -110,6 +113,9 @@ struct nfs_server {
                                                   filesystem */
 #endif
        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  */
 };
 
 /* Server capabilities */