fs/nfsd/nfs4recover.c - fp2-dev/kernel/msm - Gitiles

 /*
 *  linux/fs/nfsd/nfs4recover.c
 *
 *  Copyright (c) 2004 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson <andros@citi.umich.edu>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

 #include <linux/err.h>
 #include <linux/sunrpc/svc.h>
 #include <linux/nfsd/nfsd.h>
 #include <linux/nfs4.h>
 #include <linux/nfsd/state.h>
 #include <linux/nfsd/xdr4.h>
 #include <linux/param.h>
 #include <linux/file.h>
 #include <linux/namei.h>
 #include <asm/uaccess.h>
 #include <linux/scatterlist.h>
 #include <linux/crypto.h>
 #include <linux/sched.h>
 #include <linux/mount.h>

 #define NFSDDBG_FACILITY                NFSDDBG_PROC

 /* Globals */
 static struct path rec_dir;
 static int rec_dir_init = 0;

 static int
 nfs4_save_creds(const struct cred **original_creds)
 {
 	struct cred *new;

 	new = prepare_creds();
 	if (!new)
 		return -ENOMEM;

 	new->fsuid = 0;
 	new->fsgid = 0;
 	*original_creds = override_creds(new);
 	put_cred(new);
 	return 0;
 }

 static void
 nfs4_reset_creds(const struct cred *original)
 {
 	revert_creds(original);
 }

 static void
 md5_to_hex(char *out, char *md5)
 {
 	int i;

 	for (i=0; i<16; i++) {
 		unsigned char c = md5[i];

 		*out++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
 		*out++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
 	}
 	*out = '\0';
 }

 __be32
 nfs4_make_rec_clidname(char *dname, struct xdr_netobj *clname)
 {
 	struct xdr_netobj cksum;
 	struct hash_desc desc;
 	struct scatterlist sg;
 	__be32 status = nfserr_resource;

 	dprintk("NFSD: nfs4_make_rec_clidname for %.*s\n",
 			clname->len, clname->data);
 	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 	desc.tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
 	if (IS_ERR(desc.tfm))
 		goto out_no_tfm;
 	cksum.len = crypto_hash_digestsize(desc.tfm);
 	cksum.data = kmalloc(cksum.len, GFP_KERNEL);
 	if (cksum.data == NULL)
  		goto out;

 	sg_init_one(&sg, clname->data, clname->len);

 	if (crypto_hash_digest(&desc, &sg, sg.length, cksum.data))
 		goto out;

 	md5_to_hex(dname, cksum.data);

 	status = nfs_ok;
 out:
 	kfree(cksum.data);
 	crypto_free_hash(desc.tfm);
 out_no_tfm:
 	return status;
 }

 static void
 nfsd4_sync_rec_dir(void)
 {
 	mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
 	nfsd_sync_dir(rec_dir.dentry);
 	mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
 }

 int
 nfsd4_create_clid_dir(struct nfs4_client *clp)
 {
 	const struct cred *original_cred;
 	char *dname = clp->cl_recdir;
 	struct dentry *dentry;
 	int status;

 	dprintk("NFSD: nfsd4_create_clid_dir for \"%s\"\n", dname);

 	if (!rec_dir_init || clp->cl_firststate)
 		return 0;

 	status = nfs4_save_creds(&original_cred);
 	if (status < 0)
 		return status;

 	/* lock the parent */
 	mutex_lock(&rec_dir.dentry->d_inode->i_mutex);

 	dentry = lookup_one_len(dname, rec_dir.dentry, HEXDIR_LEN-1);
 	if (IS_ERR(dentry)) {
 		status = PTR_ERR(dentry);
 		goto out_unlock;
 	}
 	status = -EEXIST;
 	if (dentry->d_inode) {
 		dprintk("NFSD: nfsd4_create_clid_dir: DIRECTORY EXISTS\n");
 		goto out_put;
 	}
 	status = mnt_want_write(rec_dir.mnt);
 	if (status)
 		goto out_put;
 	status = vfs_mkdir(rec_dir.dentry->d_inode, dentry, S_IRWXU);
 	mnt_drop_write(rec_dir.mnt);
 out_put:
 	dput(dentry);
 out_unlock:
 	mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
 	if (status == 0) {
 		clp->cl_firststate = 1;
 		nfsd4_sync_rec_dir();
 	}
 	nfs4_reset_creds(original_cred);
 	dprintk("NFSD: nfsd4_create_clid_dir returns %d\n", status);
 	return status;
 }

 typedef int (recdir_func)(struct dentry *, struct dentry *);

 struct dentry_list {
 	struct dentry *dentry;
 	struct list_head list;
 };

 struct dentry_list_arg {
 	struct list_head dentries;
 	struct dentry *parent;
 };

 static int
 nfsd4_build_dentrylist(void *arg, const char *name, int namlen,
 		loff_t offset, u64 ino, unsigned int d_type)
 {
 	struct dentry_list_arg *dla = arg;
 	struct list_head *dentries = &dla->dentries;
 	struct dentry *parent = dla->parent;
 	struct dentry *dentry;
 	struct dentry_list *child;

 	if (name && isdotent(name, namlen))
 		return 0;
 	dentry = lookup_one_len(name, parent, namlen);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 	child = kmalloc(sizeof(*child), GFP_KERNEL);
 	if (child == NULL)
 		return -ENOMEM;
 	child->dentry = dentry;
 	list_add(&child->list, dentries);
 	return 0;
 }

 static int
 nfsd4_list_rec_dir(struct dentry *dir, recdir_func *f)
 {
 	const struct cred *original_cred;
 	struct file *filp;
 	struct dentry_list_arg dla = {
 		.parent = dir,
 	};
 	struct list_head *dentries = &dla.dentries;
 	struct dentry_list *child;
 	int status;

 	if (!rec_dir_init)
 		return 0;

 	status = nfs4_save_creds(&original_cred);
 	if (status < 0)
 		return status;
 	INIT_LIST_HEAD(dentries);

 	filp = dentry_open(dget(dir), mntget(rec_dir.mnt), O_RDONLY,
 			   current_cred());
 	status = PTR_ERR(filp);
 	if (IS_ERR(filp))
 		goto out;
 	INIT_LIST_HEAD(dentries);
 	status = vfs_readdir(filp, nfsd4_build_dentrylist, &dla);
 	fput(filp);
 	while (!list_empty(dentries)) {
 		child = list_entry(dentries->next, struct dentry_list, list);
 		status = f(dir, child->dentry);
 		if (status)
 			goto out;
 		list_del(&child->list);
 		dput(child->dentry);
 		kfree(child);
 	}
 out:
 	while (!list_empty(dentries)) {
 		child = list_entry(dentries->next, struct dentry_list, list);
 		list_del(&child->list);
 		dput(child->dentry);
 		kfree(child);
 	}
 	nfs4_reset_creds(original_cred);
 	return status;
 }

 static int
 nfsd4_remove_clid_file(struct dentry *dir, struct dentry *dentry)
 {
 	int status;

 	if (!S_ISREG(dir->d_inode->i_mode)) {
 		printk("nfsd4: non-file found in client recovery directory\n");
 		return -EINVAL;
 	}
 	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 	status = vfs_unlink(dir->d_inode, dentry);
 	mutex_unlock(&dir->d_inode->i_mutex);
 	return status;
 }

 static int
 nfsd4_clear_clid_dir(struct dentry *dir, struct dentry *dentry)
 {
 	int status;

 	/* For now this directory should already be empty, but we empty it of
 	 * any regular files anyway, just in case the directory was created by
 	 * a kernel from the future.... */
 	nfsd4_list_rec_dir(dentry, nfsd4_remove_clid_file);
 	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 	status = vfs_rmdir(dir->d_inode, dentry);
 	mutex_unlock(&dir->d_inode->i_mutex);
 	return status;
 }

 static int
 nfsd4_unlink_clid_dir(char *name, int namlen)
 {
 	struct dentry *dentry;
 	int status;

 	dprintk("NFSD: nfsd4_unlink_clid_dir. name %.*s\n", namlen, name);

 	mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
 	dentry = lookup_one_len(name, rec_dir.dentry, namlen);
 	mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
 	if (IS_ERR(dentry)) {
 		status = PTR_ERR(dentry);
 		return status;
 	}
 	status = -ENOENT;
 	if (!dentry->d_inode)
 		goto out;

 	status = nfsd4_clear_clid_dir(rec_dir.dentry, dentry);
 out:
 	dput(dentry);
 	return status;
 }

 void
 nfsd4_remove_clid_dir(struct nfs4_client *clp)
 {
 	const struct cred *original_cred;
 	int status;

 	if (!rec_dir_init || !clp->cl_firststate)
 		return;

 	status = mnt_want_write(rec_dir.mnt);
 	if (status)
 		goto out;
 	clp->cl_firststate = 0;

 	status = nfs4_save_creds(&original_cred);
 	if (status < 0)
 		goto out;

 	status = nfsd4_unlink_clid_dir(clp->cl_recdir, HEXDIR_LEN-1);
 	nfs4_reset_creds(original_cred);
 	if (status == 0)
 		nfsd4_sync_rec_dir();
 	mnt_drop_write(rec_dir.mnt);
 out:
 	if (status)
 		printk("NFSD: Failed to remove expired client state directory"
 				" %.*s\n", HEXDIR_LEN, clp->cl_recdir);
 	return;
 }

 static int
 purge_old(struct dentry *parent, struct dentry *child)
 {
 	int status;

 	if (nfs4_has_reclaimed_state(child->d_name.name))
 		return 0;

 	status = nfsd4_clear_clid_dir(parent, child);
 	if (status)
 		printk("failed to remove client recovery directory %s\n",
 				child->d_name.name);
 	/* Keep trying, success or failure: */
 	return 0;
 }

 void
 nfsd4_recdir_purge_old(void) {
 	int status;

 	if (!rec_dir_init)
 		return;
 	status = mnt_want_write(rec_dir.mnt);
 	if (status)
 		goto out;
 	status = nfsd4_list_rec_dir(rec_dir.dentry, purge_old);
 	if (status == 0)
 		nfsd4_sync_rec_dir();
 	mnt_drop_write(rec_dir.mnt);
 out:
 	if (status)
 		printk("nfsd4: failed to purge old clients from recovery"
 			" directory %s\n", rec_dir.dentry->d_name.name);
 }

 static int
 load_recdir(struct dentry *parent, struct dentry *child)
 {
 	if (child->d_name.len != HEXDIR_LEN - 1) {
 		printk("nfsd4: illegal name %s in recovery directory\n",
 				child->d_name.name);
 		/* Keep trying; maybe the others are OK: */
 		return 0;
 	}
 	nfs4_client_to_reclaim(child->d_name.name);
 	return 0;
 }

 int
 nfsd4_recdir_load(void) {
 	int status;

 	status = nfsd4_list_rec_dir(rec_dir.dentry, load_recdir);
 	if (status)
 		printk("nfsd4: failed loading clients from recovery"
 			" directory %s\n", rec_dir.dentry->d_name.name);
 	return status;
 }

 /*
  * Hold reference to the recovery directory.
  */

 void
 nfsd4_init_recdir(char *rec_dirname)
 {
 	const struct cred *original_cred;
 	int status;

 	printk("NFSD: Using %s as the NFSv4 state recovery directory\n",
 			rec_dirname);

 	BUG_ON(rec_dir_init);

 	status = nfs4_save_creds(&original_cred);
 	if (status < 0) {
 		printk("NFSD: Unable to change credentials to find recovery"
 		       " directory: error %d\n",
 		       status);
 		return;
 	}

 	status = kern_path(rec_dirname, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
 			&rec_dir);
 	if (status)
 		printk("NFSD: unable to find recovery directory %s\n",
 				rec_dirname);

 	if (!status)
 		rec_dir_init = 1;
 	nfs4_reset_creds(original_cred);
 }

 void
 nfsd4_shutdown_recdir(void)
 {
 	if (!rec_dir_init)
 		return;
 	rec_dir_init = 0;
 	path_put(&rec_dir);
 }
	/*
	* linux/fs/nfsd/nfs4recover.c
	*
	* Copyright (c) 2004 The Regents of the University of Michigan.
	* All rights reserved.
	*
	* Andy Adamson <andros@citi.umich.edu>
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the name of the University nor the names of its
	* contributors may be used to endorse or promote products derived
	* from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
	* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
	* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
	* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	*/

	#include <linux/err.h>
	#include <linux/sunrpc/svc.h>
	#include <linux/nfsd/nfsd.h>
	#include <linux/nfs4.h>
	#include <linux/nfsd/state.h>
	#include <linux/nfsd/xdr4.h>
	#include <linux/param.h>
	#include <linux/file.h>
	#include <linux/namei.h>
	#include <asm/uaccess.h>
	#include <linux/scatterlist.h>
	#include <linux/crypto.h>
	#include <linux/sched.h>
	#include <linux/mount.h>

	#define NFSDDBG_FACILITY NFSDDBG_PROC

	/* Globals */
	static struct path rec_dir;
	static int rec_dir_init = 0;

	static int
	nfs4_save_creds(const struct cred **original_creds)
	{
	struct cred *new;

	new = prepare_creds();
	if (!new)
	return -ENOMEM;

	new->fsuid = 0;
	new->fsgid = 0;
	*original_creds = override_creds(new);
	put_cred(new);
	return 0;
	}

	static void
	nfs4_reset_creds(const struct cred *original)
	{
	revert_creds(original);
	}

	static void
	md5_to_hex(char out, char md5)
	{
	int i;

	for (i=0; i<16; i++) {
	unsigned char c = md5[i];

	out++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)('a'-'9'-1);
	out++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)('a'-'9'-1);
	}
	*out = '\0';
	}

	__be32
	nfs4_make_rec_clidname(char dname, struct xdr_netobj clname)
	{
	struct xdr_netobj cksum;
	struct hash_desc desc;
	struct scatterlist sg;
	__be32 status = nfserr_resource;

	dprintk("NFSD: nfs4_make_rec_clidname for %.*s\n",
	clname->len, clname->data);
	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
	desc.tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(desc.tfm))
	goto out_no_tfm;
	cksum.len = crypto_hash_digestsize(desc.tfm);
	cksum.data = kmalloc(cksum.len, GFP_KERNEL);
	if (cksum.data == NULL)
	goto out;

	sg_init_one(&sg, clname->data, clname->len);

	if (crypto_hash_digest(&desc, &sg, sg.length, cksum.data))
	goto out;

	md5_to_hex(dname, cksum.data);

	status = nfs_ok;
	out:
	kfree(cksum.data);
	crypto_free_hash(desc.tfm);
	out_no_tfm:
	return status;
	}

	static void
	nfsd4_sync_rec_dir(void)
	{
	mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
	nfsd_sync_dir(rec_dir.dentry);
	mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
	}

	int
	nfsd4_create_clid_dir(struct nfs4_client *clp)
	{
	const struct cred *original_cred;
	char *dname = clp->cl_recdir;
	struct dentry *dentry;
	int status;

	dprintk("NFSD: nfsd4_create_clid_dir for \"%s\"\n", dname);

	if (!rec_dir_init \|\| clp->cl_firststate)
	return 0;

	status = nfs4_save_creds(&original_cred);
	if (status < 0)
	return status;

	/* lock the parent */
	mutex_lock(&rec_dir.dentry->d_inode->i_mutex);

	dentry = lookup_one_len(dname, rec_dir.dentry, HEXDIR_LEN-1);
	if (IS_ERR(dentry)) {
	status = PTR_ERR(dentry);
	goto out_unlock;
	}
	status = -EEXIST;
	if (dentry->d_inode) {
	dprintk("NFSD: nfsd4_create_clid_dir: DIRECTORY EXISTS\n");
	goto out_put;
	}
	status = mnt_want_write(rec_dir.mnt);
	if (status)
	goto out_put;
	status = vfs_mkdir(rec_dir.dentry->d_inode, dentry, S_IRWXU);
	mnt_drop_write(rec_dir.mnt);
	out_put:
	dput(dentry);
	out_unlock:
	mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
	if (status == 0) {
	clp->cl_firststate = 1;
	nfsd4_sync_rec_dir();
	}
	nfs4_reset_creds(original_cred);
	dprintk("NFSD: nfsd4_create_clid_dir returns %d\n", status);
	return status;
	}

	typedef int (recdir_func)(struct dentry , struct dentry );

	struct dentry_list {
	struct dentry *dentry;
	struct list_head list;
	};

	struct dentry_list_arg {
	struct list_head dentries;
	struct dentry *parent;
	};

	static int
	nfsd4_build_dentrylist(void arg, const char name, int namlen,
	loff_t offset, u64 ino, unsigned int d_type)
	{
	struct dentry_list_arg *dla = arg;
	struct list_head *dentries = &dla->dentries;
	struct dentry *parent = dla->parent;
	struct dentry *dentry;
	struct dentry_list *child;

	if (name && isdotent(name, namlen))
	return 0;
	dentry = lookup_one_len(name, parent, namlen);
	if (IS_ERR(dentry))
	return PTR_ERR(dentry);
	child = kmalloc(sizeof(*child), GFP_KERNEL);
	if (child == NULL)
	return -ENOMEM;
	child->dentry = dentry;
	list_add(&child->list, dentries);
	return 0;
	}

	static int
	nfsd4_list_rec_dir(struct dentry dir, recdir_func f)
	{
	const struct cred *original_cred;
	struct file *filp;
	struct dentry_list_arg dla = {
	.parent = dir,
	};
	struct list_head *dentries = &dla.dentries;
	struct dentry_list *child;
	int status;

	if (!rec_dir_init)
	return 0;

	status = nfs4_save_creds(&original_cred);
	if (status < 0)
	return status;
	INIT_LIST_HEAD(dentries);

	filp = dentry_open(dget(dir), mntget(rec_dir.mnt), O_RDONLY,
	current_cred());
	status = PTR_ERR(filp);
	if (IS_ERR(filp))
	goto out;
	INIT_LIST_HEAD(dentries);
	status = vfs_readdir(filp, nfsd4_build_dentrylist, &dla);
	fput(filp);
	while (!list_empty(dentries)) {
	child = list_entry(dentries->next, struct dentry_list, list);
	status = f(dir, child->dentry);
	if (status)
	goto out;
	list_del(&child->list);
	dput(child->dentry);
	kfree(child);
	}
	out:
	while (!list_empty(dentries)) {
	child = list_entry(dentries->next, struct dentry_list, list);
	list_del(&child->list);
	dput(child->dentry);
	kfree(child);
	}
	nfs4_reset_creds(original_cred);
	return status;
	}

	static int
	nfsd4_remove_clid_file(struct dentry dir, struct dentry dentry)
	{
	int status;

	if (!S_ISREG(dir->d_inode->i_mode)) {
	printk("nfsd4: non-file found in client recovery directory\n");
	return -EINVAL;
	}
	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
	status = vfs_unlink(dir->d_inode, dentry);
	mutex_unlock(&dir->d_inode->i_mutex);
	return status;
	}

	static int
	nfsd4_clear_clid_dir(struct dentry dir, struct dentry dentry)
	{
	int status;

	/* For now this directory should already be empty, but we empty it of
	* any regular files anyway, just in case the directory was created by
	* a kernel from the future.... */
	nfsd4_list_rec_dir(dentry, nfsd4_remove_clid_file);
	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
	status = vfs_rmdir(dir->d_inode, dentry);
	mutex_unlock(&dir->d_inode->i_mutex);
	return status;
	}

	static int
	nfsd4_unlink_clid_dir(char *name, int namlen)
	{
	struct dentry *dentry;
	int status;

	dprintk("NFSD: nfsd4_unlink_clid_dir. name %.*s\n", namlen, name);

	mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
	dentry = lookup_one_len(name, rec_dir.dentry, namlen);
	mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
	if (IS_ERR(dentry)) {
	status = PTR_ERR(dentry);
	return status;
	}
	status = -ENOENT;
	if (!dentry->d_inode)
	goto out;

	status = nfsd4_clear_clid_dir(rec_dir.dentry, dentry);
	out:
	dput(dentry);
	return status;
	}

	void
	nfsd4_remove_clid_dir(struct nfs4_client *clp)
	{
	const struct cred *original_cred;
	int status;

	if (!rec_dir_init \|\| !clp->cl_firststate)
	return;

	status = mnt_want_write(rec_dir.mnt);
	if (status)
	goto out;
	clp->cl_firststate = 0;

	status = nfs4_save_creds(&original_cred);
	if (status < 0)
	goto out;

	status = nfsd4_unlink_clid_dir(clp->cl_recdir, HEXDIR_LEN-1);
	nfs4_reset_creds(original_cred);
	if (status == 0)
	nfsd4_sync_rec_dir();
	mnt_drop_write(rec_dir.mnt);
	out:
	if (status)
	printk("NFSD: Failed to remove expired client state directory"
	" %.*s\n", HEXDIR_LEN, clp->cl_recdir);
	return;
	}

	static int
	purge_old(struct dentry parent, struct dentry child)
	{
	int status;

	if (nfs4_has_reclaimed_state(child->d_name.name))
	return 0;

	status = nfsd4_clear_clid_dir(parent, child);
	if (status)
	printk("failed to remove client recovery directory %s\n",
	child->d_name.name);
	/* Keep trying, success or failure: */
	return 0;
	}

	void
	nfsd4_recdir_purge_old(void) {
	int status;

	if (!rec_dir_init)
	return;
	status = mnt_want_write(rec_dir.mnt);
	if (status)
	goto out;
	status = nfsd4_list_rec_dir(rec_dir.dentry, purge_old);
	if (status == 0)
	nfsd4_sync_rec_dir();
	mnt_drop_write(rec_dir.mnt);
	out:
	if (status)
	printk("nfsd4: failed to purge old clients from recovery"
	" directory %s\n", rec_dir.dentry->d_name.name);
	}

	static int
	load_recdir(struct dentry parent, struct dentry child)
	{
	if (child->d_name.len != HEXDIR_LEN - 1) {
	printk("nfsd4: illegal name %s in recovery directory\n",
	child->d_name.name);
	/* Keep trying; maybe the others are OK: */
	return 0;
	}
	nfs4_client_to_reclaim(child->d_name.name);
	return 0;
	}

	int
	nfsd4_recdir_load(void) {
	int status;

	status = nfsd4_list_rec_dir(rec_dir.dentry, load_recdir);
	if (status)
	printk("nfsd4: failed loading clients from recovery"
	" directory %s\n", rec_dir.dentry->d_name.name);
	return status;
	}

	/*
	* Hold reference to the recovery directory.
	*/

	void
	nfsd4_init_recdir(char *rec_dirname)
	{
	const struct cred *original_cred;
	int status;

	printk("NFSD: Using %s as the NFSv4 state recovery directory\n",
	rec_dirname);

	BUG_ON(rec_dir_init);

	status = nfs4_save_creds(&original_cred);
	if (status < 0) {
	printk("NFSD: Unable to change credentials to find recovery"
	" directory: error %d\n",
	status);
	return;
	}

	status = kern_path(rec_dirname, LOOKUP_FOLLOW \| LOOKUP_DIRECTORY,
	&rec_dir);
	if (status)
	printk("NFSD: unable to find recovery directory %s\n",
	rec_dirname);

	if (!status)
	rec_dir_init = 1;
	nfs4_reset_creds(original_cred);
	}

	void
	nfsd4_shutdown_recdir(void)
	{
	if (!rec_dir_init)
	return;
	rec_dir_init = 0;
	path_put(&rec_dir);
	}