fs/lockd/svcsubs.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/fs/lockd/svcsubs.c
  *
  * Various support routines for the NLM server.
  *
  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  */

 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/time.h>
 #include <linux/in.h>
 #include <linux/slab.h>
 #include <linux/mutex.h>
 #include <linux/sunrpc/svc.h>
 #include <linux/sunrpc/addr.h>
 #include <linux/lockd/lockd.h>
 #include <linux/lockd/share.h>
 #include <linux/module.h>
 #include <linux/mount.h>
 #include <uapi/linux/nfs2.h>

 #define NLMDBG_FACILITY		NLMDBG_SVCSUBS


 /*
  * Global file hash table
  */
 #define FILE_HASH_BITS		7
 #define FILE_NRHASH		(1<<FILE_HASH_BITS)
 static struct hlist_head	nlm_files[FILE_NRHASH];
 static DEFINE_MUTEX(nlm_file_mutex);

 #ifdef CONFIG_SUNRPC_DEBUG
 static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
 {
 	u32 *fhp = (u32*)f->data;

 	/* print the first 32 bytes of the fh */
 	dprintk("lockd: %s (%08x %08x %08x %08x %08x %08x %08x %08x)\n",
 		msg, fhp[0], fhp[1], fhp[2], fhp[3],
 		fhp[4], fhp[5], fhp[6], fhp[7]);
 }

 static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
 {
 	struct inode *inode = nlmsvc_file_inode(file);

 	dprintk("lockd: %s %s/%ld\n",
 		msg, inode->i_sb->s_id, inode->i_ino);
 }
 #else
 static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
 {
 	return;
 }

 static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
 {
 	return;
 }
 #endif

 static inline unsigned int file_hash(struct nfs_fh *f)
 {
 	unsigned int tmp=0;
 	int i;
 	for (i=0; i<NFS2_FHSIZE;i++)
 		tmp += f->data[i];
 	return tmp & (FILE_NRHASH - 1);
 }

 int lock_to_openmode(struct file_lock *lock)
 {
 	return (lock->fl_type == F_WRLCK) ? O_WRONLY : O_RDONLY;
 }

 /*
  * Open the file. Note that if we're reexporting, for example,
  * this could block the lockd thread for a while.
  *
  * We have to make sure we have the right credential to open
  * the file.
  */
 static __be32 nlm_do_fopen(struct svc_rqst *rqstp,
 			   struct nlm_file *file, int mode)
 {
 	struct file **fp = &file->f_file[mode];
 	__be32	nfserr;

 	if (*fp)
 		return 0;
 	nfserr = nlmsvc_ops->fopen(rqstp, &file->f_handle, fp, mode);
 	if (nfserr)
 		dprintk("lockd: open failed (error %d)\n", nfserr);
 	return nfserr;
 }

 /*
  * Lookup file info. If it doesn't exist, create a file info struct
  * and open a (VFS) file for the given inode.
  */
 __be32
 nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
 					struct nlm_lock *lock)
 {
 	struct nlm_file	*file;
 	unsigned int	hash;
 	__be32		nfserr;
 	int		mode;

 	nlm_debug_print_fh("nlm_lookup_file", &lock->fh);

 	hash = file_hash(&lock->fh);
 	mode = lock_to_openmode(&lock->fl);

 	/* Lock file table */
 	mutex_lock(&nlm_file_mutex);

 	hlist_for_each_entry(file, &nlm_files[hash], f_list)
 		if (!nfs_compare_fh(&file->f_handle, &lock->fh)) {
 			mutex_lock(&file->f_mutex);
 			nfserr = nlm_do_fopen(rqstp, file, mode);
 			mutex_unlock(&file->f_mutex);
 			goto found;
 		}
 	nlm_debug_print_fh("creating file for", &lock->fh);

 	nfserr = nlm_lck_denied_nolocks;
 	file = kzalloc(sizeof(*file), GFP_KERNEL);
 	if (!file)
 		goto out_free;

 	memcpy(&file->f_handle, &lock->fh, sizeof(struct nfs_fh));
 	mutex_init(&file->f_mutex);
 	INIT_HLIST_NODE(&file->f_list);
 	INIT_LIST_HEAD(&file->f_blocks);

 	nfserr = nlm_do_fopen(rqstp, file, mode);
 	if (nfserr)
 		goto out_unlock;

 	hlist_add_head(&file->f_list, &nlm_files[hash]);

 found:
 	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
 	*result = file;
 	file->f_count++;

 out_unlock:
 	mutex_unlock(&nlm_file_mutex);
 	return nfserr;

 out_free:
 	kfree(file);
 	goto out_unlock;
 }

 /*
  * Delete a file after having released all locks, blocks and shares
  */
 static inline void
 nlm_delete_file(struct nlm_file *file)
 {
 	nlm_debug_print_file("closing file", file);
 	if (!hlist_unhashed(&file->f_list)) {
 		hlist_del(&file->f_list);
 		if (file->f_file[O_RDONLY])
 			nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
 		if (file->f_file[O_WRONLY])
 			nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
 		kfree(file);
 	} else {
 		printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
 	}
 }

 static int nlm_unlock_files(struct nlm_file *file, fl_owner_t owner)
 {
 	struct file_lock lock;

 	locks_init_lock(&lock);
 	lock.fl_type  = F_UNLCK;
 	lock.fl_start = 0;
 	lock.fl_end   = OFFSET_MAX;
 	lock.fl_owner = owner;
 	if (file->f_file[O_RDONLY] &&
 	    vfs_lock_file(file->f_file[O_RDONLY], F_SETLK, &lock, NULL))
 		goto out_err;
 	if (file->f_file[O_WRONLY] &&
 	    vfs_lock_file(file->f_file[O_WRONLY], F_SETLK, &lock, NULL))
 		goto out_err;
 	return 0;
 out_err:
 	pr_warn("lockd: unlock failure in %s:%d\n", __FILE__, __LINE__);
 	return 1;
 }

 /*
  * Loop over all locks on the given file and perform the specified
  * action.
  */
 static int
 nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
 			nlm_host_match_fn_t match)
 {
 	struct inode	 *inode = nlmsvc_file_inode(file);
 	struct file_lock *fl;
 	struct file_lock_context *flctx = inode->i_flctx;
 	struct nlm_host	 *lockhost;

 	if (!flctx || list_empty_careful(&flctx->flc_posix))
 		return 0;
 again:
 	file->f_locks = 0;
 	spin_lock(&flctx->flc_lock);
 	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
 		if (fl->fl_lmops != &nlmsvc_lock_operations)
 			continue;

 		/* update current lock count */
 		file->f_locks++;

 		lockhost = ((struct nlm_lockowner *)fl->fl_owner)->host;
 		if (match(lockhost, host)) {

 			spin_unlock(&flctx->flc_lock);
 			if (nlm_unlock_files(file, fl->fl_owner))
 				return 1;
 			goto again;
 		}
 	}
 	spin_unlock(&flctx->flc_lock);

 	return 0;
 }

 static int
 nlmsvc_always_match(void *dummy1, struct nlm_host *dummy2)
 {
 	return 1;
 }

 /*
  * Inspect a single file
  */
 static inline int
 nlm_inspect_file(struct nlm_host *host, struct nlm_file *file, nlm_host_match_fn_t match)
 {
 	nlmsvc_traverse_blocks(host, file, match);
 	nlmsvc_traverse_shares(host, file, match);
 	return nlm_traverse_locks(host, file, match);
 }

 /*
  * Quick check whether there are still any locks, blocks or
  * shares on a given file.
  */
 static inline int
 nlm_file_inuse(struct nlm_file *file)
 {
 	struct inode	 *inode = nlmsvc_file_inode(file);
 	struct file_lock *fl;
 	struct file_lock_context *flctx = inode->i_flctx;

 	if (file->f_count || !list_empty(&file->f_blocks) || file->f_shares)
 		return 1;

 	if (flctx && !list_empty_careful(&flctx->flc_posix)) {
 		spin_lock(&flctx->flc_lock);
 		list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
 			if (fl->fl_lmops == &nlmsvc_lock_operations) {
 				spin_unlock(&flctx->flc_lock);
 				return 1;
 			}
 		}
 		spin_unlock(&flctx->flc_lock);
 	}
 	file->f_locks = 0;
 	return 0;
 }

 static void nlm_close_files(struct nlm_file *file)
 {
 	if (file->f_file[O_RDONLY])
 		nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
 	if (file->f_file[O_WRONLY])
 		nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
 }

 /*
  * Loop over all files in the file table.
  */
 static int
 nlm_traverse_files(void *data, nlm_host_match_fn_t match,
 		int (*is_failover_file)(void *data, struct nlm_file *file))
 {
 	struct hlist_node *next;
 	struct nlm_file	*file;
 	int i, ret = 0;

 	mutex_lock(&nlm_file_mutex);
 	for (i = 0; i < FILE_NRHASH; i++) {
 		hlist_for_each_entry_safe(file, next, &nlm_files[i], f_list) {
 			if (is_failover_file && !is_failover_file(data, file))
 				continue;
 			file->f_count++;
 			mutex_unlock(&nlm_file_mutex);

 			/* Traverse locks, blocks and shares of this file
 			 * and update file->f_locks count */
 			if (nlm_inspect_file(data, file, match))
 				ret = 1;

 			mutex_lock(&nlm_file_mutex);
 			file->f_count--;
 			/* No more references to this file. Let go of it. */
 			if (list_empty(&file->f_blocks) && !file->f_locks
 			 && !file->f_shares && !file->f_count) {
 				hlist_del(&file->f_list);
 				nlm_close_files(file);
 				kfree(file);
 			}
 		}
 	}
 	mutex_unlock(&nlm_file_mutex);
 	return ret;
 }

 /*
  * Release file. If there are no more remote locks on this file,
  * close it and free the handle.
  *
  * Note that we can't do proper reference counting without major
  * contortions because the code in fs/locks.c creates, deletes and
  * splits locks without notification. Our only way is to walk the
  * entire lock list each time we remove a lock.
  */
 void
 nlm_release_file(struct nlm_file *file)
 {
 	dprintk("lockd: nlm_release_file(%p, ct = %d)\n",
 				file, file->f_count);

 	/* Lock file table */
 	mutex_lock(&nlm_file_mutex);

 	/* If there are no more locks etc, delete the file */
 	if (--file->f_count == 0 && !nlm_file_inuse(file))
 		nlm_delete_file(file);

 	mutex_unlock(&nlm_file_mutex);
 }

 /*
  * Helpers function for resource traversal
  *
  * nlmsvc_mark_host:
  *	used by the garbage collector; simply sets h_inuse only for those
  *	hosts, which passed network check.
  *	Always returns 0.
  *
  * nlmsvc_same_host:
  *	returns 1 iff the two hosts match. Used to release
  *	all resources bound to a specific host.
  *
  * nlmsvc_is_client:
  *	returns 1 iff the host is a client.
  *	Used by nlmsvc_invalidate_all
  */

 static int
 nlmsvc_mark_host(void *data, struct nlm_host *hint)
 {
 	struct nlm_host *host = data;

 	if ((hint->net == NULL) ||
 	    (host->net == hint->net))
 		host->h_inuse = 1;
 	return 0;
 }

 static int
 nlmsvc_same_host(void *data, struct nlm_host *other)
 {
 	struct nlm_host *host = data;

 	return host == other;
 }

 static int
 nlmsvc_is_client(void *data, struct nlm_host *dummy)
 {
 	struct nlm_host *host = data;

 	if (host->h_server) {
 		/* we are destroying locks even though the client
 		 * hasn't asked us too, so don't unmonitor the
 		 * client
 		 */
 		if (host->h_nsmhandle)
 			host->h_nsmhandle->sm_sticky = 1;
 		return 1;
 	} else
 		return 0;
 }

 /*
  * Mark all hosts that still hold resources
  */
 void
 nlmsvc_mark_resources(struct net *net)
 {
 	struct nlm_host hint;

 	dprintk("lockd: %s for net %x\n", __func__, net ? net->ns.inum : 0);
 	hint.net = net;
 	nlm_traverse_files(&hint, nlmsvc_mark_host, NULL);
 }

 /*
  * Release all resources held by the given client
  */
 void
 nlmsvc_free_host_resources(struct nlm_host *host)
 {
 	dprintk("lockd: nlmsvc_free_host_resources\n");

 	if (nlm_traverse_files(host, nlmsvc_same_host, NULL)) {
 		printk(KERN_WARNING
 			"lockd: couldn't remove all locks held by %s\n",
 			host->h_name);
 		BUG();
 	}
 }

 /**
  * nlmsvc_invalidate_all - remove all locks held for clients
  *
  * Release all locks held by NFS clients.
  *
  */
 void
 nlmsvc_invalidate_all(void)
 {
 	/*
 	 * Previously, the code would call
 	 * nlmsvc_free_host_resources for each client in
 	 * turn, which is about as inefficient as it gets.
 	 * Now we just do it once in nlm_traverse_files.
 	 */
 	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
 }


 static int
 nlmsvc_match_sb(void *datap, struct nlm_file *file)
 {
 	struct super_block *sb = datap;

 	return sb == nlmsvc_file_inode(file)->i_sb;
 }

 /**
  * nlmsvc_unlock_all_by_sb - release locks held on this file system
  * @sb: super block
  *
  * Release all locks held by clients accessing this file system.
  */
 int
 nlmsvc_unlock_all_by_sb(struct super_block *sb)
 {
 	int ret;

 	ret = nlm_traverse_files(sb, nlmsvc_always_match, nlmsvc_match_sb);
 	return ret ? -EIO : 0;
 }
 EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_sb);

 static int
 nlmsvc_match_ip(void *datap, struct nlm_host *host)
 {
 	return rpc_cmp_addr(nlm_srcaddr(host), datap);
 }

 /**
  * nlmsvc_unlock_all_by_ip - release local locks by IP address
  * @server_addr: server's IP address as seen by clients
  *
  * Release all locks held by clients accessing this host
  * via the passed in IP address.
  */
 int
 nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr)
 {
 	int ret;

 	ret = nlm_traverse_files(server_addr, nlmsvc_match_ip, NULL);
 	return ret ? -EIO : 0;
 }
 EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_ip);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* linux/fs/lockd/svcsubs.c
	*
	* Various support routines for the NLM server.
	*
	* Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
	*/

	#include <linux/types.h>
	#include <linux/string.h>
	#include <linux/time.h>
	#include <linux/in.h>
	#include <linux/slab.h>
	#include <linux/mutex.h>
	#include <linux/sunrpc/svc.h>
	#include <linux/sunrpc/addr.h>
	#include <linux/lockd/lockd.h>
	#include <linux/lockd/share.h>
	#include <linux/module.h>
	#include <linux/mount.h>
	#include <uapi/linux/nfs2.h>

	#define NLMDBG_FACILITY NLMDBG_SVCSUBS


	/*
	* Global file hash table
	*/
	#define FILE_HASH_BITS 7
	#define FILE_NRHASH (1<<FILE_HASH_BITS)
	static struct hlist_head nlm_files[FILE_NRHASH];
	static DEFINE_MUTEX(nlm_file_mutex);

	#ifdef CONFIG_SUNRPC_DEBUG
	static inline void nlm_debug_print_fh(char msg, struct nfs_fh f)
	{
	u32 fhp = (u32)f->data;

	/* print the first 32 bytes of the fh */
	dprintk("lockd: %s (%08x %08x %08x %08x %08x %08x %08x %08x)\n",
	msg, fhp[0], fhp[1], fhp[2], fhp[3],
	fhp[4], fhp[5], fhp[6], fhp[7]);
	}

	static inline void nlm_debug_print_file(char msg, struct nlm_file file)
	{
	struct inode *inode = nlmsvc_file_inode(file);

	dprintk("lockd: %s %s/%ld\n",
	msg, inode->i_sb->s_id, inode->i_ino);
	}
	#else
	static inline void nlm_debug_print_fh(char msg, struct nfs_fh f)
	{
	return;
	}

	static inline void nlm_debug_print_file(char msg, struct nlm_file file)
	{
	return;
	}
	#endif

	static inline unsigned int file_hash(struct nfs_fh *f)
	{
	unsigned int tmp=0;
	int i;
	for (i=0; i<NFS2_FHSIZE;i++)
	tmp += f->data[i];
	return tmp & (FILE_NRHASH - 1);
	}

	int lock_to_openmode(struct file_lock *lock)
	{
	return (lock->fl_type == F_WRLCK) ? O_WRONLY : O_RDONLY;
	}

	/*
	* Open the file. Note that if we're reexporting, for example,
	* this could block the lockd thread for a while.
	*
	* We have to make sure we have the right credential to open
	* the file.
	*/
	static __be32 nlm_do_fopen(struct svc_rqst *rqstp,
	struct nlm_file *file, int mode)
	{
	struct file **fp = &file->f_file[mode];
	__be32 nfserr;

	if (*fp)
	return 0;
	nfserr = nlmsvc_ops->fopen(rqstp, &file->f_handle, fp, mode);
	if (nfserr)
	dprintk("lockd: open failed (error %d)\n", nfserr);
	return nfserr;
	}

	/*
	* Lookup file info. If it doesn't exist, create a file info struct
	* and open a (VFS) file for the given inode.
	*/
	__be32
	nlm_lookup_file(struct svc_rqst rqstp, struct nlm_file *result,
	struct nlm_lock *lock)
	{
	struct nlm_file *file;
	unsigned int hash;
	__be32 nfserr;
	int mode;

	nlm_debug_print_fh("nlm_lookup_file", &lock->fh);

	hash = file_hash(&lock->fh);
	mode = lock_to_openmode(&lock->fl);

	/* Lock file table */
	mutex_lock(&nlm_file_mutex);

	hlist_for_each_entry(file, &nlm_files[hash], f_list)
	if (!nfs_compare_fh(&file->f_handle, &lock->fh)) {
	mutex_lock(&file->f_mutex);
	nfserr = nlm_do_fopen(rqstp, file, mode);
	mutex_unlock(&file->f_mutex);
	goto found;
	}
	nlm_debug_print_fh("creating file for", &lock->fh);

	nfserr = nlm_lck_denied_nolocks;
	file = kzalloc(sizeof(*file), GFP_KERNEL);
	if (!file)
	goto out_free;

	memcpy(&file->f_handle, &lock->fh, sizeof(struct nfs_fh));
	mutex_init(&file->f_mutex);
	INIT_HLIST_NODE(&file->f_list);
	INIT_LIST_HEAD(&file->f_blocks);

	nfserr = nlm_do_fopen(rqstp, file, mode);
	if (nfserr)
	goto out_unlock;

	hlist_add_head(&file->f_list, &nlm_files[hash]);

	found:
	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
	*result = file;
	file->f_count++;

	out_unlock:
	mutex_unlock(&nlm_file_mutex);
	return nfserr;

	out_free:
	kfree(file);
	goto out_unlock;
	}

	/*
	* Delete a file after having released all locks, blocks and shares
	*/
	static inline void
	nlm_delete_file(struct nlm_file *file)
	{
	nlm_debug_print_file("closing file", file);
	if (!hlist_unhashed(&file->f_list)) {
	hlist_del(&file->f_list);
	if (file->f_file[O_RDONLY])
	nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
	if (file->f_file[O_WRONLY])
	nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
	kfree(file);
	} else {
	printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
	}
	}

	static int nlm_unlock_files(struct nlm_file *file, fl_owner_t owner)
	{
	struct file_lock lock;

	locks_init_lock(&lock);
	lock.fl_type = F_UNLCK;
	lock.fl_start = 0;
	lock.fl_end = OFFSET_MAX;
	lock.fl_owner = owner;
	if (file->f_file[O_RDONLY] &&
	vfs_lock_file(file->f_file[O_RDONLY], F_SETLK, &lock, NULL))
	goto out_err;
	if (file->f_file[O_WRONLY] &&
	vfs_lock_file(file->f_file[O_WRONLY], F_SETLK, &lock, NULL))
	goto out_err;
	return 0;
	out_err:
	pr_warn("lockd: unlock failure in %s:%d\n", __FILE__, __LINE__);
	return 1;
	}

	/*
	* Loop over all locks on the given file and perform the specified
	* action.
	*/
	static int
	nlm_traverse_locks(struct nlm_host host, struct nlm_file file,
	nlm_host_match_fn_t match)
	{
	struct inode *inode = nlmsvc_file_inode(file);
	struct file_lock *fl;
	struct file_lock_context *flctx = inode->i_flctx;
	struct nlm_host *lockhost;

	if (!flctx \|\| list_empty_careful(&flctx->flc_posix))
	return 0;
	again:
	file->f_locks = 0;
	spin_lock(&flctx->flc_lock);
	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
	if (fl->fl_lmops != &nlmsvc_lock_operations)
	continue;

	/* update current lock count */
	file->f_locks++;

	lockhost = ((struct nlm_lockowner *)fl->fl_owner)->host;
	if (match(lockhost, host)) {

	spin_unlock(&flctx->flc_lock);
	if (nlm_unlock_files(file, fl->fl_owner))
	return 1;
	goto again;
	}
	}
	spin_unlock(&flctx->flc_lock);

	return 0;
	}

	static int
	nlmsvc_always_match(void dummy1, struct nlm_host dummy2)
	{
	return 1;
	}

	/*
	* Inspect a single file
	*/
	static inline int
	nlm_inspect_file(struct nlm_host host, struct nlm_file file, nlm_host_match_fn_t match)
	{
	nlmsvc_traverse_blocks(host, file, match);
	nlmsvc_traverse_shares(host, file, match);
	return nlm_traverse_locks(host, file, match);
	}

	/*
	* Quick check whether there are still any locks, blocks or
	* shares on a given file.
	*/
	static inline int
	nlm_file_inuse(struct nlm_file *file)
	{
	struct inode *inode = nlmsvc_file_inode(file);
	struct file_lock *fl;
	struct file_lock_context *flctx = inode->i_flctx;

	if (file->f_count \|\| !list_empty(&file->f_blocks) \|\| file->f_shares)
	return 1;

	if (flctx && !list_empty_careful(&flctx->flc_posix)) {
	spin_lock(&flctx->flc_lock);
	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
	if (fl->fl_lmops == &nlmsvc_lock_operations) {
	spin_unlock(&flctx->flc_lock);
	return 1;
	}
	}
	spin_unlock(&flctx->flc_lock);
	}
	file->f_locks = 0;
	return 0;
	}

	static void nlm_close_files(struct nlm_file *file)
	{
	if (file->f_file[O_RDONLY])
	nlmsvc_ops->fclose(file->f_file[O_RDONLY]);
	if (file->f_file[O_WRONLY])
	nlmsvc_ops->fclose(file->f_file[O_WRONLY]);
	}

	/*
	* Loop over all files in the file table.
	*/
	static int
	nlm_traverse_files(void *data, nlm_host_match_fn_t match,
	int (is_failover_file)(void data, struct nlm_file *file))
	{
	struct hlist_node *next;
	struct nlm_file *file;
	int i, ret = 0;

	mutex_lock(&nlm_file_mutex);
	for (i = 0; i < FILE_NRHASH; i++) {
	hlist_for_each_entry_safe(file, next, &nlm_files[i], f_list) {
	if (is_failover_file && !is_failover_file(data, file))
	continue;
	file->f_count++;
	mutex_unlock(&nlm_file_mutex);

	/* Traverse locks, blocks and shares of this file
	* and update file->f_locks count */
	if (nlm_inspect_file(data, file, match))
	ret = 1;

	mutex_lock(&nlm_file_mutex);
	file->f_count--;
	/* No more references to this file. Let go of it. */
	if (list_empty(&file->f_blocks) && !file->f_locks
	&& !file->f_shares && !file->f_count) {
	hlist_del(&file->f_list);
	nlm_close_files(file);
	kfree(file);
	}
	}
	}
	mutex_unlock(&nlm_file_mutex);
	return ret;
	}

	/*
	* Release file. If there are no more remote locks on this file,
	* close it and free the handle.
	*
	* Note that we can't do proper reference counting without major
	* contortions because the code in fs/locks.c creates, deletes and
	* splits locks without notification. Our only way is to walk the
	* entire lock list each time we remove a lock.
	*/
	void
	nlm_release_file(struct nlm_file *file)
	{
	dprintk("lockd: nlm_release_file(%p, ct = %d)\n",
	file, file->f_count);

	/* Lock file table */
	mutex_lock(&nlm_file_mutex);

	/* If there are no more locks etc, delete the file */
	if (--file->f_count == 0 && !nlm_file_inuse(file))
	nlm_delete_file(file);

	mutex_unlock(&nlm_file_mutex);
	}

	/*
	* Helpers function for resource traversal
	*
	* nlmsvc_mark_host:
	* used by the garbage collector; simply sets h_inuse only for those
	* hosts, which passed network check.
	* Always returns 0.
	*
	* nlmsvc_same_host:
	* returns 1 iff the two hosts match. Used to release
	* all resources bound to a specific host.
	*
	* nlmsvc_is_client:
	* returns 1 iff the host is a client.
	* Used by nlmsvc_invalidate_all
	*/

	static int
	nlmsvc_mark_host(void data, struct nlm_host hint)
	{
	struct nlm_host *host = data;

	if ((hint->net == NULL) \|\|
	(host->net == hint->net))
	host->h_inuse = 1;
	return 0;
	}

	static int
	nlmsvc_same_host(void data, struct nlm_host other)
	{
	struct nlm_host *host = data;

	return host == other;
	}

	static int
	nlmsvc_is_client(void data, struct nlm_host dummy)
	{
	struct nlm_host *host = data;

	if (host->h_server) {
	/* we are destroying locks even though the client
	* hasn't asked us too, so don't unmonitor the
	* client
	*/
	if (host->h_nsmhandle)
	host->h_nsmhandle->sm_sticky = 1;
	return 1;
	} else
	return 0;
	}

	/*
	* Mark all hosts that still hold resources
	*/
	void
	nlmsvc_mark_resources(struct net *net)
	{
	struct nlm_host hint;

	dprintk("lockd: %s for net %x\n", __func__, net ? net->ns.inum : 0);
	hint.net = net;
	nlm_traverse_files(&hint, nlmsvc_mark_host, NULL);
	}

	/*
	* Release all resources held by the given client
	*/
	void
	nlmsvc_free_host_resources(struct nlm_host *host)
	{
	dprintk("lockd: nlmsvc_free_host_resources\n");

	if (nlm_traverse_files(host, nlmsvc_same_host, NULL)) {
	printk(KERN_WARNING
	"lockd: couldn't remove all locks held by %s\n",
	host->h_name);
	BUG();
	}
	}

	/**
	* nlmsvc_invalidate_all - remove all locks held for clients
	*
	* Release all locks held by NFS clients.
	*
	*/
	void
	nlmsvc_invalidate_all(void)
	{
	/*
	* Previously, the code would call
	* nlmsvc_free_host_resources for each client in
	* turn, which is about as inefficient as it gets.
	* Now we just do it once in nlm_traverse_files.
	*/
	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
	}


	static int
	nlmsvc_match_sb(void datap, struct nlm_file file)
	{
	struct super_block *sb = datap;

	return sb == nlmsvc_file_inode(file)->i_sb;
	}

	/**
	* nlmsvc_unlock_all_by_sb - release locks held on this file system
	* @sb: super block
	*
	* Release all locks held by clients accessing this file system.
	*/
	int
	nlmsvc_unlock_all_by_sb(struct super_block *sb)
	{
	int ret;

	ret = nlm_traverse_files(sb, nlmsvc_always_match, nlmsvc_match_sb);
	return ret ? -EIO : 0;
	}
	EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_sb);

	static int
	nlmsvc_match_ip(void datap, struct nlm_host host)
	{
	return rpc_cmp_addr(nlm_srcaddr(host), datap);
	}

	/**
	* nlmsvc_unlock_all_by_ip - release local locks by IP address
	* @server_addr: server's IP address as seen by clients
	*
	* Release all locks held by clients accessing this host
	* via the passed in IP address.
	*/
	int
	nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr)
	{
	int ret;

	ret = nlm_traverse_files(server_addr, nlmsvc_match_ip, NULL);
	return ret ? -EIO : 0;
	}
	EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_ip);