1 files changed, 500 insertions, 120 deletions

diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index a65c7b53d55..de54129336c 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -3,7 +3,6 @@
  *
  * nfs sillydelete handling
  *
- * NOTE: we rely on holding the BKL for list manipulation protection.
  */
 
 #include <linux/slab.h>
@@ -12,49 +11,29 @@
 #include <linux/sunrpc/sched.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/nfs_fs.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/namei.h>
+#include <linux/fsnotify.h>
 
+#include "internal.h"
+#include "nfs4_fs.h"
+#include "iostat.h"
+#include "delegation.h"
 
-struct nfs_unlinkdata {
-	struct nfs_unlinkdata	*next;
-	struct dentry	*dir, *dentry;
-	struct qstr	name;
-	struct rpc_task	task;
-	struct rpc_cred	*cred;
-	unsigned int	count;
-};
-
-static struct nfs_unlinkdata	*nfs_deletes;
-static RPC_WAITQ(nfs_delete_queue, "nfs_delete_queue");
+#include "nfstrace.h"
 
 /**
- * nfs_detach_unlinkdata - Remove asynchronous unlink from global list
- * @data: pointer to descriptor
- */
-static inline void
-nfs_detach_unlinkdata(struct nfs_unlinkdata *data)
-{
-	struct nfs_unlinkdata	**q;
-
-	for (q = &nfs_deletes; *q != NULL; q = &((*q)->next)) {
-		if (*q == data) {
-			*q = data->next;
-			break;
-		}
-	}
-}
-
-/**
- * nfs_put_unlinkdata - release data from a sillydelete operation.
+ * nfs_free_unlinkdata - release data from a sillydelete operation.
  * @data: pointer to unlink structure.
  */
 static void
-nfs_put_unlinkdata(struct nfs_unlinkdata *data)
+nfs_free_unlinkdata(struct nfs_unlinkdata *data)
 {
-	if (--data->count == 0) {
-		nfs_detach_unlinkdata(data);
-		kfree(data->name.name);
-		kfree(data);
-	}
+	iput(data->dir);
+	put_rpccred(data->cred);
+	kfree(data->args.name.name);
+	kfree(data);
 }
 
 #define NAME_ALLOC_LEN(len)	((len+16) & ~15)
@@ -63,50 +42,31 @@ nfs_put_unlinkdata(struct nfs_unlinkdata *data)
  * @dentry: pointer to dentry
  * @data: nfs_unlinkdata
  */
-static inline void
-nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
+static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
 {
 	char		*str;
 	int		len = dentry->d_name.len;
 
-	str = kmalloc(NAME_ALLOC_LEN(len), GFP_KERNEL);
+	str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
 	if (!str)
-		return;
-	memcpy(str, dentry->d_name.name, len);
-	if (!data->name.len) {
-		data->name.len = len;
-		data->name.name = str;
-	} else
-		kfree(str);
+		return -ENOMEM;
+	data->args.name.len = len;
+	data->args.name.name = str;
+	return 0;
 }
 
-/**
- * nfs_async_unlink_init - Initialize the RPC info
- * @task: rpc_task of the sillydelete
- *
- * We delay initializing RPC info until after the call to dentry_iput()
- * in order to minimize races against rename().
- */
-static void nfs_async_unlink_init(struct rpc_task *task, void *calldata)
+static void nfs_free_dname(struct nfs_unlinkdata *data)
 {
-	struct nfs_unlinkdata	*data = calldata;
-	struct dentry		*dir = data->dir;
-	struct rpc_message	msg = {
-		.rpc_cred	= data->cred,
-	};
-	int			status = -ENOENT;
-
-	if (!data->name.len)
-		goto out_err;
+	kfree(data->args.name.name);
+	data->args.name.name = NULL;
+	data->args.name.len = 0;
+}
 
-	status = NFS_PROTO(dir->d_inode)->unlink_setup(&msg, dir, &data->name);
-	if (status < 0)
-		goto out_err;
-	nfs_begin_data_update(dir->d_inode);
-	rpc_call_setup(task, &msg, 0);
-	return;
- out_err:
-	rpc_exit(task, status);
+static void nfs_dec_sillycount(struct inode *dir)
+{
+	struct nfs_inode *nfsi = NFS_I(dir);
+	if (atomic_dec_return(&nfsi->silly_count) == 1)
+		wake_up(&nfsi->waitqueue);
 }
 
 /**
@@ -117,19 +77,12 @@ static void nfs_async_unlink_init(struct rpc_task *task, void *calldata)
  */
 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
 {
-	struct nfs_unlinkdata	*data = calldata;
-	struct dentry		*dir = data->dir;
-	struct inode		*dir_i;
+	struct nfs_unlinkdata *data = calldata;
+	struct inode *dir = data->dir;
 
-	if (!dir)
-		return;
-	dir_i = dir->d_inode;
-	nfs_end_data_update(dir_i);
-	if (NFS_PROTO(dir_i)->unlink_done(dir, task))
-		return;
-	put_rpccred(data->cred);
-	data->cred = NULL;
-	dput(dir);
+	trace_nfs_sillyrename_unlink(data, task->tk_status);
+	if (!NFS_PROTO(dir)->unlink_done(task, dir))
+		rpc_restart_call_prepare(task);
 }
 
 /**
@@ -142,83 +95,510 @@ static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
 static void nfs_async_unlink_release(void *calldata)
 {
 	struct nfs_unlinkdata	*data = calldata;
-	nfs_put_unlinkdata(data);
+	struct super_block *sb = data->dir->i_sb;
+
+	nfs_dec_sillycount(data->dir);
+	nfs_free_unlinkdata(data);
+	nfs_sb_deactive(sb);
+}
+
+static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
+{
+	struct nfs_unlinkdata *data = calldata;
+	NFS_PROTO(data->dir)->unlink_rpc_prepare(task, data);
 }
 
 static const struct rpc_call_ops nfs_unlink_ops = {
-	.rpc_call_prepare = nfs_async_unlink_init,
 	.rpc_call_done = nfs_async_unlink_done,
 	.rpc_release = nfs_async_unlink_release,
+	.rpc_call_prepare = nfs_unlink_prepare,
 };
 
+static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
+{
+	struct rpc_message msg = {
+		.rpc_argp = &data->args,
+		.rpc_resp = &data->res,
+		.rpc_cred = data->cred,
+	};
+	struct rpc_task_setup task_setup_data = {
+		.rpc_message = &msg,
+		.callback_ops = &nfs_unlink_ops,
+		.callback_data = data,
+		.workqueue = nfsiod_workqueue,
+		.flags = RPC_TASK_ASYNC,
+	};
+	struct rpc_task *task;
+	struct dentry *alias;
+
+	alias = d_lookup(parent, &data->args.name);
+	if (alias != NULL) {
+		int ret;
+		void *devname_garbage = NULL;
+
+		/*
+		 * Hey, we raced with lookup... See if we need to transfer
+		 * the sillyrename information to the aliased dentry.
+		 */
+		nfs_free_dname(data);
+		ret = nfs_copy_dname(alias, data);
+		spin_lock(&alias->d_lock);
+		if (ret == 0 && alias->d_inode != NULL &&
+		    !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
+			devname_garbage = alias->d_fsdata;
+			alias->d_fsdata = data;
+			alias->d_flags |= DCACHE_NFSFS_RENAMED;
+			ret = 1;
+		} else
+			ret = 0;
+		spin_unlock(&alias->d_lock);
+		nfs_dec_sillycount(dir);
+		dput(alias);
+		/*
+		 * If we'd displaced old cached devname, free it.  At that
+		 * point dentry is definitely not a root, so we won't need
+		 * that anymore.
+		 */
+		kfree(devname_garbage);
+		return ret;
+	}
+	data->dir = igrab(dir);
+	if (!data->dir) {
+		nfs_dec_sillycount(dir);
+		return 0;
+	}
+	nfs_sb_active(dir->i_sb);
+	data->args.fh = NFS_FH(dir);
+	nfs_fattr_init(data->res.dir_attr);
+
+	NFS_PROTO(dir)->unlink_setup(&msg, dir);
+
+	task_setup_data.rpc_client = NFS_CLIENT(dir);
+	task = rpc_run_task(&task_setup_data);
+	if (!IS_ERR(task))
+		rpc_put_task_async(task);
+	return 1;
+}
+
+static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
+{
+	struct dentry *parent;
+	struct inode *dir;
+	int ret = 0;
+
+
+	parent = dget_parent(dentry);
+	if (parent == NULL)
+		goto out_free;
+	dir = parent->d_inode;
+	/* Non-exclusive lock protects against concurrent lookup() calls */
+	spin_lock(&dir->i_lock);
+	if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
+		/* Deferred delete */
+		hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
+		spin_unlock(&dir->i_lock);
+		ret = 1;
+		goto out_dput;
+	}
+	spin_unlock(&dir->i_lock);
+	ret = nfs_do_call_unlink(parent, dir, data);
+out_dput:
+	dput(parent);
+out_free:
+	return ret;
+}
+
+void nfs_wait_on_sillyrename(struct dentry *dentry)
+{
+	struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
+
+	wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) <= 1);
+}
+
+void nfs_block_sillyrename(struct dentry *dentry)
+{
+	struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
+
+	wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
+}
+
+void nfs_unblock_sillyrename(struct dentry *dentry)
+{
+	struct inode *dir = dentry->d_inode;
+	struct nfs_inode *nfsi = NFS_I(dir);
+	struct nfs_unlinkdata *data;
+
+	atomic_inc(&nfsi->silly_count);
+	spin_lock(&dir->i_lock);
+	while (!hlist_empty(&nfsi->silly_list)) {
+		if (!atomic_inc_not_zero(&nfsi->silly_count))
+			break;
+		data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
+		hlist_del(&data->list);
+		spin_unlock(&dir->i_lock);
+		if (nfs_do_call_unlink(dentry, dir, data) == 0)
+			nfs_free_unlinkdata(data);
+		spin_lock(&dir->i_lock);
+	}
+	spin_unlock(&dir->i_lock);
+}
+
 /**
  * nfs_async_unlink - asynchronous unlinking of a file
+ * @dir: parent directory of dentry
  * @dentry: dentry to unlink
  */
-int
-nfs_async_unlink(struct dentry *dentry)
+static int
+nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 {
-	struct dentry	*dir = dentry->d_parent;
-	struct nfs_unlinkdata	*data;
-	struct rpc_clnt	*clnt = NFS_CLIENT(dir->d_inode);
-	int		status = -ENOMEM;
+	struct nfs_unlinkdata *data;
+	int status = -ENOMEM;
+	void *devname_garbage = NULL;
 
-	data = kmalloc(sizeof(*data), GFP_KERNEL);
-	if (!data)
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (data == NULL)
 		goto out;
-	memset(data, 0, sizeof(*data));
 
-	data->cred = rpcauth_lookupcred(clnt->cl_auth, 0);
+	data->cred = rpc_lookup_cred();
 	if (IS_ERR(data->cred)) {
 		status = PTR_ERR(data->cred);
 		goto out_free;
 	}
-	data->dir = dget(dir);
-	data->dentry = dentry;
-
-	data->next = nfs_deletes;
-	nfs_deletes = data;
-	data->count = 1;
-
-	rpc_init_task(&data->task, clnt, RPC_TASK_ASYNC, &nfs_unlink_ops, data);
+	data->res.dir_attr = &data->dir_attr;
 
+	status = -EBUSY;
 	spin_lock(&dentry->d_lock);
+	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
+		goto out_unlock;
 	dentry->d_flags |= DCACHE_NFSFS_RENAMED;
+	devname_garbage = dentry->d_fsdata;
+	dentry->d_fsdata = data;
 	spin_unlock(&dentry->d_lock);
-
-	rpc_sleep_on(&nfs_delete_queue, &data->task, NULL, NULL);
-	status = 0;
- out:
-	return status;
+	/*
+	 * If we'd displaced old cached devname, free it.  At that
+	 * point dentry is definitely not a root, so we won't need
+	 * that anymore.
+	 */
+	kfree(devname_garbage);
+	return 0;
+out_unlock:
+	spin_unlock(&dentry->d_lock);
+	put_rpccred(data->cred);
 out_free:
 	kfree(data);
+out:
 	return status;
 }
 
 /**
  * nfs_complete_unlink - Initialize completion of the sillydelete
  * @dentry: dentry to delete
+ * @inode: inode
  *
  * Since we're most likely to be called by dentry_iput(), we
  * only use the dentry to find the sillydelete. We then copy the name
  * into the qstr.
  */
 void
-nfs_complete_unlink(struct dentry *dentry)
+nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 {
-	struct nfs_unlinkdata	*data;
+	struct nfs_unlinkdata	*data = NULL;
 
-	for(data = nfs_deletes; data != NULL; data = data->next) {
-		if (dentry == data->dentry)
-			break;
+	spin_lock(&dentry->d_lock);
+	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
+		dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
+		data = dentry->d_fsdata;
+		dentry->d_fsdata = NULL;
 	}
-	if (!data)
-		return;
-	data->count++;
-	nfs_copy_dname(dentry, data);
+	spin_unlock(&dentry->d_lock);
+
+	if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
+		nfs_free_unlinkdata(data);
+}
+
+/* Cancel a queued async unlink. Called when a sillyrename run fails. */
+static void
+nfs_cancel_async_unlink(struct dentry *dentry)
+{
 	spin_lock(&dentry->d_lock);
-	dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
+	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
+		struct nfs_unlinkdata *data = dentry->d_fsdata;
+
+		dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
+		dentry->d_fsdata = NULL;
+		spin_unlock(&dentry->d_lock);
+		nfs_free_unlinkdata(data);
+		return;
+	}
 	spin_unlock(&dentry->d_lock);
-	rpc_wake_up_task(&data->task);
-	nfs_put_unlinkdata(data);
+}
+
+/**
+ * nfs_async_rename_done - Sillyrename post-processing
+ * @task: rpc_task of the sillyrename
+ * @calldata: nfs_renamedata for the sillyrename
+ *
+ * Do the directory attribute updates and the d_move
+ */
+static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
+{
+	struct nfs_renamedata *data = calldata;
+	struct inode *old_dir = data->old_dir;
+	struct inode *new_dir = data->new_dir;
+	struct dentry *old_dentry = data->old_dentry;
+
+	trace_nfs_sillyrename_rename(old_dir, old_dentry,
+			new_dir, data->new_dentry, task->tk_status);
+	if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
+		rpc_restart_call_prepare(task);
+		return;
+	}
+
+	if (data->complete)
+		data->complete(task, data);
+}
+
+/**
+ * nfs_async_rename_release - Release the sillyrename data.
+ * @calldata: the struct nfs_renamedata to be released
+ */
+static void nfs_async_rename_release(void *calldata)
+{
+	struct nfs_renamedata	*data = calldata;
+	struct super_block *sb = data->old_dir->i_sb;
+
+	if (data->old_dentry->d_inode)
+		nfs_mark_for_revalidate(data->old_dentry->d_inode);
+
+	dput(data->old_dentry);
+	dput(data->new_dentry);
+	iput(data->old_dir);
+	iput(data->new_dir);
+	nfs_sb_deactive(sb);
+	put_rpccred(data->cred);
+	kfree(data);
+}
+
+static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
+{
+	struct nfs_renamedata *data = calldata;
+	NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
+}
+
+static const struct rpc_call_ops nfs_rename_ops = {
+	.rpc_call_done = nfs_async_rename_done,
+	.rpc_release = nfs_async_rename_release,
+	.rpc_call_prepare = nfs_rename_prepare,
+};
+
+/**
+ * nfs_async_rename - perform an asynchronous rename operation
+ * @old_dir: directory that currently holds the dentry to be renamed
+ * @new_dir: target directory for the rename
+ * @old_dentry: original dentry to be renamed
+ * @new_dentry: dentry to which the old_dentry should be renamed
+ *
+ * It's expected that valid references to the dentries and inodes are held
+ */
+struct rpc_task *
+nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
+		 struct dentry *old_dentry, struct dentry *new_dentry,
+		 void (*complete)(struct rpc_task *, struct nfs_renamedata *))
+{
+	struct nfs_renamedata *data;
+	struct rpc_message msg = { };
+	struct rpc_task_setup task_setup_data = {
+		.rpc_message = &msg,
+		.callback_ops = &nfs_rename_ops,
+		.workqueue = nfsiod_workqueue,
+		.rpc_client = NFS_CLIENT(old_dir),
+		.flags = RPC_TASK_ASYNC,
+	};
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (data == NULL)
+		return ERR_PTR(-ENOMEM);
+	task_setup_data.callback_data = data;
+
+	data->cred = rpc_lookup_cred();
+	if (IS_ERR(data->cred)) {
+		struct rpc_task *task = ERR_CAST(data->cred);
+		kfree(data);
+		return task;
+	}
+
+	msg.rpc_argp = &data->args;
+	msg.rpc_resp = &data->res;
+	msg.rpc_cred = data->cred;
+
+	/* set up nfs_renamedata */
+	data->old_dir = old_dir;
+	ihold(old_dir);
+	data->new_dir = new_dir;
+	ihold(new_dir);
+	data->old_dentry = dget(old_dentry);
+	data->new_dentry = dget(new_dentry);
+	nfs_fattr_init(&data->old_fattr);
+	nfs_fattr_init(&data->new_fattr);
+	data->complete = complete;
+
+	/* set up nfs_renameargs */
+	data->args.old_dir = NFS_FH(old_dir);
+	data->args.old_name = &old_dentry->d_name;
+	data->args.new_dir = NFS_FH(new_dir);
+	data->args.new_name = &new_dentry->d_name;
+
+	/* set up nfs_renameres */
+	data->res.old_fattr = &data->old_fattr;
+	data->res.new_fattr = &data->new_fattr;
+
+	nfs_sb_active(old_dir->i_sb);
+
+	NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);
+
+	return rpc_run_task(&task_setup_data);
+}
+
+/*
+ * Perform tasks needed when a sillyrename is done such as cancelling the
+ * queued async unlink if it failed.
+ */
+static void
+nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
+{
+	struct dentry *dentry = data->old_dentry;
+
+	if (task->tk_status != 0) {
+		nfs_cancel_async_unlink(dentry);
+		return;
+	}
+
+	/*
+	 * vfs_unlink and the like do not issue this when a file is
+	 * sillyrenamed, so do it here.
+	 */
+	fsnotify_nameremove(dentry, 0);
+}
+
+#define SILLYNAME_PREFIX ".nfs"
+#define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
+#define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
+#define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
+#define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
+		SILLYNAME_FILEID_LEN + \
+		SILLYNAME_COUNTER_LEN)
+
+/**
+ * nfs_sillyrename - Perform a silly-rename of a dentry
+ * @dir: inode of directory that contains dentry
+ * @dentry: dentry to be sillyrenamed
+ *
+ * NFSv2/3 is stateless and the server doesn't know when the client is
+ * holding a file open. To prevent application problems when a file is
+ * unlinked while it's still open, the client performs a "silly-rename".
+ * That is, it renames the file to a hidden file in the same directory,
+ * and only performs the unlink once the last reference to it is put.
+ *
+ * The final cleanup is done during dentry_iput.
+ *
+ * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
+ * could take responsibility for keeping open files referenced.  The server
+ * would also need to ensure that opened-but-deleted files were kept over
+ * reboots.  However, we may not assume a server does so.  (RFC 5661
+ * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
+ * use to advertise that it does this; some day we may take advantage of
+ * it.))
+ */
+int
+nfs_sillyrename(struct inode *dir, struct dentry *dentry)
+{
+	static unsigned int sillycounter;
+	unsigned char silly[SILLYNAME_LEN + 1];
+	unsigned long long fileid;
+	struct dentry *sdentry;
+	struct rpc_task *task;
+	int            error = -EBUSY;
+
+	dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
+		dentry, d_count(dentry));
+	nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
+
+	/*
+	 * We don't allow a dentry to be silly-renamed twice.
+	 */
+	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
+		goto out;
+
+	fileid = NFS_FILEID(dentry->d_inode);
+
+	/* Return delegation in anticipation of the rename */
+	NFS_PROTO(dentry->d_inode)->return_delegation(dentry->d_inode);
+
+	sdentry = NULL;
+	do {
+		int slen;
+		dput(sdentry);
+		sillycounter++;
+		slen = scnprintf(silly, sizeof(silly),
+				SILLYNAME_PREFIX "%0*llx%0*x",
+				SILLYNAME_FILEID_LEN, fileid,
+				SILLYNAME_COUNTER_LEN, sillycounter);
+
+		dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
+				dentry, silly);
+
+		sdentry = lookup_one_len(silly, dentry->d_parent, slen);
+		/*
+		 * N.B. Better to return EBUSY here ... it could be
+		 * dangerous to delete the file while it's in use.
+		 */
+		if (IS_ERR(sdentry))
+			goto out;
+	} while (sdentry->d_inode != NULL); /* need negative lookup */
+
+	/* queue unlink first. Can't do this from rpc_release as it
+	 * has to allocate memory
+	 */
+	error = nfs_async_unlink(dir, dentry);
+	if (error)
+		goto out_dput;
+
+	/* populate unlinkdata with the right dname */
+	error = nfs_copy_dname(sdentry,
+				(struct nfs_unlinkdata *)dentry->d_fsdata);
+	if (error) {
+		nfs_cancel_async_unlink(dentry);
+		goto out_dput;
+	}
+
+	/* run the rename task, undo unlink if it fails */
+	task = nfs_async_rename(dir, dir, dentry, sdentry,
+					nfs_complete_sillyrename);
+	if (IS_ERR(task)) {
+		error = -EBUSY;
+		nfs_cancel_async_unlink(dentry);
+		goto out_dput;
+	}
+
+	/* wait for the RPC task to complete, unless a SIGKILL intervenes */
+	error = rpc_wait_for_completion_task(task);
+	if (error == 0)
+		error = task->tk_status;
+	switch (error) {
+	case 0:
+		/* The rename succeeded */
+		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+		d_move(dentry, sdentry);
+		break;
+	case -ERESTARTSYS:
+		/* The result of the rename is unknown. Play it safe by
+		 * forcing a new lookup */
+		d_drop(dentry);
+		d_drop(sdentry);
+	}
+	rpc_put_task(task);
+out_dput:
+	dput(sdentry);
+out:
+	return error;
 }