[linux-block.git] / fs / afs / dynroot.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS dynamic root handling
 *
 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/dns_resolver.h>
#include "internal.h"

static atomic_t afs_autocell_ino;

/*
 * iget5() comparator for inode created by autocell operations
 *
 * These pseudo inodes don't match anything.
 */
static int afs_iget5_pseudo_test(struct inode *inode, void *opaque)
{
	return 0;
}

/*
 * iget5() inode initialiser
 */
static int afs_iget5_pseudo_set(struct inode *inode, void *opaque)
{
	struct afs_super_info *as = AFS_FS_S(inode->i_sb);
	struct afs_vnode *vnode = AFS_FS_I(inode);
	struct afs_fid *fid = opaque;

	vnode->volume		= as->volume;
	vnode->fid		= *fid;
	inode->i_ino		= fid->vnode;
	inode->i_generation	= fid->unique;
	return 0;
}

/*
 * Create an inode for a dynamic root directory or an autocell dynamic
 * automount dir.
 */
struct inode *afs_iget_pseudo_dir(struct super_block *sb, bool root)
{
	struct afs_super_info *as = AFS_FS_S(sb);
	struct afs_vnode *vnode;
	struct inode *inode;
	struct afs_fid fid = {};

	_enter("");

	if (as->volume)
		fid.vid = as->volume->vid;
	if (root) {
		fid.vnode = 1;
		fid.unique = 1;
	} else {
		fid.vnode = atomic_inc_return(&afs_autocell_ino);
		fid.unique = 0;
	}

	inode = iget5_locked(sb, fid.vnode,
			     afs_iget5_pseudo_test, afs_iget5_pseudo_set, &fid);
	if (!inode) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	_debug("GOT INODE %p { ino=%lu, vl=%llx, vn=%llx, u=%x }",
	       inode, inode->i_ino, fid.vid, fid.vnode, fid.unique);

	vnode = AFS_FS_I(inode);

	/* there shouldn't be an existing inode */
	BUG_ON(!(inode->i_state & I_NEW));

	inode->i_size		= 0;
	inode->i_mode		= S_IFDIR | S_IRUGO | S_IXUGO;
	if (root) {
		inode->i_op	= &afs_dynroot_inode_operations;
		inode->i_fop	= &simple_dir_operations;
	} else {
		inode->i_op	= &afs_autocell_inode_operations;
	}
	set_nlink(inode, 2);
	inode->i_uid		= GLOBAL_ROOT_UID;
	inode->i_gid		= GLOBAL_ROOT_GID;
	inode->i_ctime = inode->i_atime = inode->i_mtime = current_time(inode);
	inode->i_blocks		= 0;
	inode->i_generation	= 0;

	set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
	if (!root) {
		set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
		inode->i_flags |= S_AUTOMOUNT;
	}

	inode->i_flags |= S_NOATIME;
	unlock_new_inode(inode);
	_leave(" = %p", inode);
	return inode;
}

/*
 * Probe to see if a cell may exist.  This prevents positive dentries from
 * being created unnecessarily.
 */
static int afs_probe_cell_name(struct dentry *dentry)
{
	struct afs_cell *cell;
	struct afs_net *net = afs_d2net(dentry);
	const char *name = dentry->d_name.name;
	size_t len = dentry->d_name.len;
	int ret;

	/* Names prefixed with a dot are R/W mounts. */
	if (name[0] == '.') {
		if (len == 1)
			return -EINVAL;
		name++;
		len--;
	}

	cell = afs_lookup_cell_rcu(net, name, len);
	if (!IS_ERR(cell)) {
		afs_put_cell(net, cell);
		return 0;
	}

	ret = dns_query(net->net, "afsdb", name, len, "srv=1",
			NULL, NULL, false);
	if (ret == -ENODATA)
		ret = -EDESTADDRREQ;
	return ret;
}

/*
 * Try to auto mount the mountpoint with pseudo directory, if the autocell
 * operation is setted.
 */
struct inode *afs_try_auto_mntpt(struct dentry *dentry, struct inode *dir)
{
	struct afs_vnode *vnode = AFS_FS_I(dir);
	struct inode *inode;
	int ret = -ENOENT;

	_enter("%p{%pd}, {%llx:%llu}",
	       dentry, dentry, vnode->fid.vid, vnode->fid.vnode);

	if (!test_bit(AFS_VNODE_AUTOCELL, &vnode->flags))
		goto out;

	ret = afs_probe_cell_name(dentry);
	if (ret < 0)
		goto out;

	inode = afs_iget_pseudo_dir(dir->i_sb, false);
	if (IS_ERR(inode)) {
		ret = PTR_ERR(inode);
		goto out;
	}

	_leave("= %p", inode);
	return inode;

out:
	_leave("= %d", ret);
	return ret == -ENOENT ? NULL : ERR_PTR(ret);
}

/*
 * Look up @cell in a dynroot directory.  This is a substitution for the
 * local cell name for the net namespace.
 */
static struct dentry *afs_lookup_atcell(struct dentry *dentry)
{
	struct afs_cell *cell;
	struct afs_net *net = afs_d2net(dentry);
	struct dentry *ret;
	unsigned int seq = 0;
	char *name;
	int len;

	if (!net->ws_cell)
		return ERR_PTR(-ENOENT);

	ret = ERR_PTR(-ENOMEM);
	name = kmalloc(AFS_MAXCELLNAME + 1, GFP_KERNEL);
	if (!name)
		goto out_p;

	rcu_read_lock();
	do {
		read_seqbegin_or_lock(&net->cells_lock, &seq);
		cell = rcu_dereference_raw(net->ws_cell);
		if (cell) {
			len = cell->name_len;
			memcpy(name, cell->name, len + 1);
		}
	} while (need_seqretry(&net->cells_lock, seq));
	done_seqretry(&net->cells_lock, seq);
	rcu_read_unlock();

	ret = ERR_PTR(-ENOENT);
	if (!cell)
		goto out_n;

	ret = lookup_one_len(name, dentry->d_parent, len);

	/* We don't want to d_add() the @cell dentry here as we don't want to
	 * the cached dentry to hide changes to the local cell name.
	 */

out_n:
	kfree(name);
out_p:
	return ret;
}

/*
 * Look up an entry in a dynroot directory.
 */
static struct dentry *afs_dynroot_lookup(struct inode *dir, struct dentry *dentry,
					 unsigned int flags)
{
	_enter("%pd", dentry);

	ASSERTCMP(d_inode(dentry), ==, NULL);

	if (flags & LOOKUP_CREATE)
		return ERR_PTR(-EOPNOTSUPP);

	if (dentry->d_name.len >= AFSNAMEMAX) {
		_leave(" = -ENAMETOOLONG");
		return ERR_PTR(-ENAMETOOLONG);
	}

	if (dentry->d_name.len == 5 &&
	    memcmp(dentry->d_name.name, "@cell", 5) == 0)
		return afs_lookup_atcell(dentry);

	return d_splice_alias(afs_try_auto_mntpt(dentry, dir), dentry);
}

const struct inode_operations afs_dynroot_inode_operations = {
	.lookup		= afs_dynroot_lookup,
};

/*
 * Dirs in the dynamic root don't need revalidation.
 */
static int afs_dynroot_d_revalidate(struct dentry *dentry, unsigned int flags)
{
	return 1;
}

/*
 * Allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
 * sleep)
 * - called from dput() when d_count is going to 0.
 * - return 1 to request dentry be unhashed, 0 otherwise
 */
static int afs_dynroot_d_delete(const struct dentry *dentry)
{
	return d_really_is_positive(dentry);
}

const struct dentry_operations afs_dynroot_dentry_operations = {
	.d_revalidate	= afs_dynroot_d_revalidate,
	.d_delete	= afs_dynroot_d_delete,
	.d_release	= afs_d_release,
	.d_automount	= afs_d_automount,
};

/*
 * Create a manually added cell mount directory.
 * - The caller must hold net->proc_cells_lock
 */
int afs_dynroot_mkdir(struct afs_net *net, struct afs_cell *cell)
{
	struct super_block *sb = net->dynroot_sb;
	struct dentry *root, *subdir;
	int ret;

	if (!sb || atomic_read(&sb->s_active) == 0)
		return 0;

	/* Let the ->lookup op do the creation */
	root = sb->s_root;
	inode_lock(root->d_inode);
	subdir = lookup_one_len(cell->name, root, cell->name_len);
	if (IS_ERR(subdir)) {
		ret = PTR_ERR(subdir);
		goto unlock;
	}

	/* Note that we're retaining an extra ref on the dentry */
	subdir->d_fsdata = (void *)1UL;
	ret = 0;
unlock:
	inode_unlock(root->d_inode);
	return ret;
}

/*
 * Remove a manually added cell mount directory.
 * - The caller must hold net->proc_cells_lock
 */
void afs_dynroot_rmdir(struct afs_net *net, struct afs_cell *cell)
{
	struct super_block *sb = net->dynroot_sb;
	struct dentry *root, *subdir;

	if (!sb || atomic_read(&sb->s_active) == 0)
		return;

	root = sb->s_root;
	inode_lock(root->d_inode);

	/* Don't want to trigger a lookup call, which will re-add the cell */
	subdir = try_lookup_one_len(cell->name, root, cell->name_len);
	if (IS_ERR_OR_NULL(subdir)) {
		_debug("lookup %ld", PTR_ERR(subdir));
		goto no_dentry;
	}

	_debug("rmdir %pd %u", subdir, d_count(subdir));

	if (subdir->d_fsdata) {
		_debug("unpin %u", d_count(subdir));
		subdir->d_fsdata = NULL;
		dput(subdir);
	}
	dput(subdir);
no_dentry:
	inode_unlock(root->d_inode);
	_leave("");
}

/*
 * Populate a newly created dynamic root with cell names.
 */
int afs_dynroot_populate(struct super_block *sb)
{
	struct afs_cell *cell;
	struct afs_net *net = afs_sb2net(sb);
	int ret;

	mutex_lock(&net->proc_cells_lock);

	net->dynroot_sb = sb;
	hlist_for_each_entry(cell, &net->proc_cells, proc_link) {
		ret = afs_dynroot_mkdir(net, cell);
		if (ret < 0)
			goto error;
	}

	ret = 0;
out:
	mutex_unlock(&net->proc_cells_lock);
	return ret;

error:
	net->dynroot_sb = NULL;
	goto out;
}

/*
 * When a dynamic root that's in the process of being destroyed, depopulate it
 * of pinned directories.
 */
void afs_dynroot_depopulate(struct super_block *sb)
{
	struct afs_net *net = afs_sb2net(sb);
	struct dentry *root = sb->s_root, *subdir, *tmp;

	/* Prevent more subdirs from being created */
	mutex_lock(&net->proc_cells_lock);
	if (net->dynroot_sb == sb)
		net->dynroot_sb = NULL;
	mutex_unlock(&net->proc_cells_lock);

	if (root) {
		inode_lock(root->d_inode);

		/* Remove all the pins for dirs created for manually added cells */
		list_for_each_entry_safe(subdir, tmp, &root->d_subdirs, d_child) {
			if (subdir->d_fsdata) {
				subdir->d_fsdata = NULL;
				dput(subdir);
			}
		}

		inode_unlock(root->d_inode);
	}
}
Commit	Line	Data
b4d0d230	1	// SPDX-License-Identifier: GPL-2.0-or-later
0da0b7fd	2	/* AFS dynamic root handling
66c7e1d3 DH	3	*
	4	* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
	5	* Written by David Howells (dhowells@redhat.com)
66c7e1d3 DH	6	*/
	7
	8	#include <linux/fs.h>
	9	#include <linux/namei.h>
	10	#include <linux/dns_resolver.h>
	11	#include "internal.h"
	12
e49c7b2f DH	13	static atomic_t afs_autocell_ino;
	14
	15	/*
	16	* iget5() comparator for inode created by autocell operations
	17	*
	18	* These pseudo inodes don't match anything.
	19	*/
	20	static int afs_iget5_pseudo_test(struct inode inode, void opaque)
	21	{
	22	return 0;
	23	}
	24
	25	/*
	26	* iget5() inode initialiser
	27	*/
	28	static int afs_iget5_pseudo_set(struct inode inode, void opaque)
	29	{
	30	struct afs_super_info *as = AFS_FS_S(inode->i_sb);
	31	struct afs_vnode *vnode = AFS_FS_I(inode);
	32	struct afs_fid *fid = opaque;
	33
	34	vnode->volume = as->volume;
	35	vnode->fid = *fid;
	36	inode->i_ino = fid->vnode;
	37	inode->i_generation = fid->unique;
	38	return 0;
	39	}
	40
	41	/*
	42	* Create an inode for a dynamic root directory or an autocell dynamic
	43	* automount dir.
	44	*/
	45	struct inode afs_iget_pseudo_dir(struct super_block sb, bool root)
	46	{
	47	struct afs_super_info *as = AFS_FS_S(sb);
	48	struct afs_vnode *vnode;
	49	struct inode *inode;
	50	struct afs_fid fid = {};
	51
	52	_enter("");
	53
	54	if (as->volume)
	55	fid.vid = as->volume->vid;
	56	if (root) {
	57	fid.vnode = 1;
	58	fid.unique = 1;
	59	} else {
	60	fid.vnode = atomic_inc_return(&afs_autocell_ino);
	61	fid.unique = 0;
	62	}
	63
	64	inode = iget5_locked(sb, fid.vnode,
	65	afs_iget5_pseudo_test, afs_iget5_pseudo_set, &fid);
	66	if (!inode) {
	67	_leave(" = -ENOMEM");
	68	return ERR_PTR(-ENOMEM);
	69	}
	70
	71	_debug("GOT INODE %p { ino=%lu, vl=%llx, vn=%llx, u=%x }",
	72	inode, inode->i_ino, fid.vid, fid.vnode, fid.unique);
	73
	74	vnode = AFS_FS_I(inode);
	75
	76	/* there shouldn't be an existing inode */
77	BUG_ON(!(inode->i_state & I_NEW));
78
79	inode->i_size = 0;
80	inode->i_mode = S_IFDIR \| S_IRUGO \| S_IXUGO;
81	if (root) {
82	inode->i_op = &afs_dynroot_inode_operations;
83	inode->i_fop = &simple_dir_operations;
84	} else {
85	inode->i_op = &afs_autocell_inode_operations;
86	}
87	set_nlink(inode, 2);
88	inode->i_uid = GLOBAL_ROOT_UID;
89	inode->i_gid = GLOBAL_ROOT_GID;
90	inode->i_ctime = inode->i_atime = inode->i_mtime = current_time(inode);
91	inode->i_blocks = 0;
92	inode->i_generation = 0;
93
94	set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
95	if (!root) {
96	set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
97	inode->i_flags \|= S_AUTOMOUNT;
98	}
99
100	inode->i_flags \|= S_NOATIME;
101	unlock_new_inode(inode);
102	_leave(" = %p", inode);
103	return inode;
104	}
105
66c7e1d3 DH	106	/*
	107	* Probe to see if a cell may exist. This prevents positive dentries from
	108	* being created unnecessarily.
	109	*/
	110	static int afs_probe_cell_name(struct dentry *dentry)
	111	{
	112	struct afs_cell *cell;
a58946c1	113	struct afs_net *net = afs_d2net(dentry);
66c7e1d3 DH	114	const char *name = dentry->d_name.name;
	115	size_t len = dentry->d_name.len;
	116	int ret;
	117
	118	/* Names prefixed with a dot are R/W mounts. */
	119	if (name[0] == '.') {
	120	if (len == 1)
	121	return -EINVAL;
	122	name++;
	123	len--;
	124	}
	125
a58946c1	126	cell = afs_lookup_cell_rcu(net, name, len);
66c7e1d3	127	if (!IS_ERR(cell)) {
a58946c1	128	afs_put_cell(net, cell);
66c7e1d3 DH	129	return 0;
	130	}
	131
a58946c1 DH	132	ret = dns_query(net->net, "afsdb", name, len, "srv=1",
a58946c1 DH	133	NULL, NULL, false);
66c7e1d3 DH	134	if (ret == -ENODATA)
	135	ret = -EDESTADDRREQ;
	136	return ret;
	137	}
	138
	139	/*
	140	* Try to auto mount the mountpoint with pseudo directory, if the autocell
	141	* operation is setted.
	142	*/
	143	struct inode afs_try_auto_mntpt(struct dentry dentry, struct inode *dir)
	144	{
	145	struct afs_vnode *vnode = AFS_FS_I(dir);
	146	struct inode *inode;
	147	int ret = -ENOENT;
	148
3b6492df	149	_enter("%p{%pd}, {%llx:%llu}",
66c7e1d3 DH	150	dentry, dentry, vnode->fid.vid, vnode->fid.vnode);
	151
	152	if (!test_bit(AFS_VNODE_AUTOCELL, &vnode->flags))
	153	goto out;
	154
	155	ret = afs_probe_cell_name(dentry);
	156	if (ret < 0)
	157	goto out;
	158
	159	inode = afs_iget_pseudo_dir(dir->i_sb, false);
	160	if (IS_ERR(inode)) {
	161	ret = PTR_ERR(inode);
	162	goto out;
	163	}
	164
	165	_leave("= %p", inode);
	166	return inode;
	167
	168	out:
	169	_leave("= %d", ret);
1401a0fc	170	return ret == -ENOENT ? NULL : ERR_PTR(ret);
66c7e1d3 DH	171	}
	172
	173	/*
	174	* Look up @cell in a dynroot directory. This is a substitution for the
	175	* local cell name for the net namespace.
	176	*/
	177	static struct dentry afs_lookup_atcell(struct dentry dentry)
	178	{
	179	struct afs_cell *cell;
	180	struct afs_net *net = afs_d2net(dentry);
	181	struct dentry *ret;
	182	unsigned int seq = 0;
	183	char *name;
	184	int len;
	185
	186	if (!net->ws_cell)
	187	return ERR_PTR(-ENOENT);
	188
	189	ret = ERR_PTR(-ENOMEM);
	190	name = kmalloc(AFS_MAXCELLNAME + 1, GFP_KERNEL);
	191	if (!name)
	192	goto out_p;
	193
	194	rcu_read_lock();
	195	do {
	196	read_seqbegin_or_lock(&net->cells_lock, &seq);
	197	cell = rcu_dereference_raw(net->ws_cell);
	198	if (cell) {
	199	len = cell->name_len;
	200	memcpy(name, cell->name, len + 1);
	201	}
	202	} while (need_seqretry(&net->cells_lock, seq));
	203	done_seqretry(&net->cells_lock, seq);
	204	rcu_read_unlock();
	205
	206	ret = ERR_PTR(-ENOENT);
	207	if (!cell)
	208	goto out_n;
	209
	210	ret = lookup_one_len(name, dentry->d_parent, len);
	211
	212	/* We don't want to d_add() the @cell dentry here as we don't want to
	213	* the cached dentry to hide changes to the local cell name.
	214	*/
	215
	216	out_n:
	217	kfree(name);
	218	out_p:
	219	return ret;
	220	}
	221
	222	/*
	223	* Look up an entry in a dynroot directory.
	224	*/
	225	static struct dentry afs_dynroot_lookup(struct inode dir, struct dentry *dentry,
	226	unsigned int flags)
	227	{
66c7e1d3 DH	228	_enter("%pd", dentry);
	229
	230	ASSERTCMP(d_inode(dentry), ==, NULL);
	231
1da4bd9f DH	232	if (flags & LOOKUP_CREATE)
	233	return ERR_PTR(-EOPNOTSUPP);
	234
66c7e1d3 DH	235	if (dentry->d_name.len >= AFSNAMEMAX) {
	236	_leave(" = -ENAMETOOLONG");
	237	return ERR_PTR(-ENAMETOOLONG);
	238	}
	239
	240	if (dentry->d_name.len == 5 &&
	241	memcmp(dentry->d_name.name, "@cell", 5) == 0)
	242	return afs_lookup_atcell(dentry);
	243
1401a0fc	244	return d_splice_alias(afs_try_auto_mntpt(dentry, dir), dentry);
66c7e1d3 DH	245	}
	246
	247	const struct inode_operations afs_dynroot_inode_operations = {
	248	.lookup = afs_dynroot_lookup,
	249	};
	250
	251	/*
	252	* Dirs in the dynamic root don't need revalidation.
	253	*/
	254	static int afs_dynroot_d_revalidate(struct dentry *dentry, unsigned int flags)
	255	{
	256	return 1;
	257	}
	258
	259	/*
	260	* Allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
	261	* sleep)
	262	* - called from dput() when d_count is going to 0.
	263	* - return 1 to request dentry be unhashed, 0 otherwise
	264	*/
	265	static int afs_dynroot_d_delete(const struct dentry *dentry)
	266	{
	267	return d_really_is_positive(dentry);
	268	}
	269
	270	const struct dentry_operations afs_dynroot_dentry_operations = {
	271	.d_revalidate = afs_dynroot_d_revalidate,
	272	.d_delete = afs_dynroot_d_delete,
	273	.d_release = afs_d_release,
	274	.d_automount = afs_d_automount,
	275	};
0da0b7fd DH	276
	277	/*
	278	* Create a manually added cell mount directory.
	279	* - The caller must hold net->proc_cells_lock
	280	*/
	281	int afs_dynroot_mkdir(struct afs_net net, struct afs_cell cell)
	282	{
	283	struct super_block *sb = net->dynroot_sb;
	284	struct dentry root, subdir;
	285	int ret;
	286
	287	if (!sb \|\| atomic_read(&sb->s_active) == 0)
	288	return 0;
	289
	290	/* Let the ->lookup op do the creation */
	291	root = sb->s_root;
	292	inode_lock(root->d_inode);
	293	subdir = lookup_one_len(cell->name, root, cell->name_len);
	294	if (IS_ERR(subdir)) {
	295	ret = PTR_ERR(subdir);
	296	goto unlock;
	297	}
	298
	299	/* Note that we're retaining an extra ref on the dentry */
	300	subdir->d_fsdata = (void *)1UL;
	301	ret = 0;
	302	unlock:
	303	inode_unlock(root->d_inode);
	304	return ret;
	305	}
	306
	307	/*
	308	* Remove a manually added cell mount directory.
	309	* - The caller must hold net->proc_cells_lock
	310	*/
	311	void afs_dynroot_rmdir(struct afs_net net, struct afs_cell cell)
	312	{
	313	struct super_block *sb = net->dynroot_sb;
	314	struct dentry root, subdir;
	315
	316	if (!sb \|\| atomic_read(&sb->s_active) == 0)
	317	return;
	318
	319	root = sb->s_root;
	320	inode_lock(root->d_inode);
	321
	322	/* Don't want to trigger a lookup call, which will re-add the cell */
	323	subdir = try_lookup_one_len(cell->name, root, cell->name_len);
	324	if (IS_ERR_OR_NULL(subdir)) {
	325	_debug("lookup %ld", PTR_ERR(subdir));
	326	goto no_dentry;
	327	}
	328
	329	_debug("rmdir %pd %u", subdir, d_count(subdir));
	330
	331	if (subdir->d_fsdata) {
	332	_debug("unpin %u", d_count(subdir));
	333	subdir->d_fsdata = NULL;
	334	dput(subdir);
	335	}
	336	dput(subdir);
	337	no_dentry:
	338	inode_unlock(root->d_inode);
	339	_leave("");
340	}
341
342	/*
343	* Populate a newly created dynamic root with cell names.
344	*/
345	int afs_dynroot_populate(struct super_block *sb)
346	{
347	struct afs_cell *cell;
348	struct afs_net *net = afs_sb2net(sb);
349	int ret;
350
3b05e528	351	mutex_lock(&net->proc_cells_lock);
0da0b7fd DH	352
0da0b7fd DH	353	net->dynroot_sb = sb;
6b3944e4	354	hlist_for_each_entry(cell, &net->proc_cells, proc_link) {
0da0b7fd DH	355	ret = afs_dynroot_mkdir(net, cell);
	356	if (ret < 0)
	357	goto error;
	358	}
	359
	360	ret = 0;
	361	out:
	362	mutex_unlock(&net->proc_cells_lock);
	363	return ret;
	364
	365	error:
	366	net->dynroot_sb = NULL;
	367	goto out;
	368	}
	369
	370	/*
	371	* When a dynamic root that's in the process of being destroyed, depopulate it
	372	* of pinned directories.
	373	*/
	374	void afs_dynroot_depopulate(struct super_block *sb)
	375	{
	376	struct afs_net *net = afs_sb2net(sb);
	377	struct dentry root = sb->s_root, subdir, *tmp;
	378
	379	/* Prevent more subdirs from being created */
	380	mutex_lock(&net->proc_cells_lock);
	381	if (net->dynroot_sb == sb)
	382	net->dynroot_sb = NULL;
	383	mutex_unlock(&net->proc_cells_lock);
	384
5e0b17b0 DH	385	if (root) {
	386	inode_lock(root->d_inode);
	387
	388	/* Remove all the pins for dirs created for manually added cells */
	389	list_for_each_entry_safe(subdir, tmp, &root->d_subdirs, d_child) {
	390	if (subdir->d_fsdata) {
	391	subdir->d_fsdata = NULL;
	392	dput(subdir);
	393	}
0da0b7fd	394	}
0da0b7fd	395
5e0b17b0 DH	396	inode_unlock(root->d_inode);
5e0b17b0 DH	397	}
0da0b7fd	398	}