[linux-2.6-block.git] / fs / kernfs / mount.c

/*
 * fs/kernfs/mount.c - kernfs mount implementation
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
 *
 * This file is released under the GPLv2.
 */

#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/init.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/seq_file.h>
#include <linux/exportfs.h>

#include "kernfs-internal.h"

struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;

static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
{
	struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry));
	struct kernfs_syscall_ops *scops = root->syscall_ops;

	if (scops && scops->show_options)
		return scops->show_options(sf, root);
	return 0;
}

static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
{
	struct kernfs_node *node = kernfs_dentry_node(dentry);
	struct kernfs_root *root = kernfs_root(node);
	struct kernfs_syscall_ops *scops = root->syscall_ops;

	if (scops && scops->show_path)
		return scops->show_path(sf, node, root);

	seq_dentry(sf, dentry, " \t\n\\");
	return 0;
}

const struct super_operations kernfs_sops = {
	.statfs		= simple_statfs,
	.drop_inode	= generic_delete_inode,
	.evict_inode	= kernfs_evict_inode,

	.show_options	= kernfs_sop_show_options,
	.show_path	= kernfs_sop_show_path,
};

/*
 * Similar to kernfs_fh_get_inode, this one gets kernfs node from inode
 * number and generation
 */
struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
	const union kernfs_node_id *id)
{
	struct kernfs_node *kn;

	kn = kernfs_find_and_get_node_by_ino(root, id->ino);
	if (!kn)
		return NULL;
	if (kn->id.generation != id->generation) {
		kernfs_put(kn);
		return NULL;
	}
	return kn;
}

static struct inode *kernfs_fh_get_inode(struct super_block *sb,
		u64 ino, u32 generation)
{
	struct kernfs_super_info *info = kernfs_info(sb);
	struct inode *inode;
	struct kernfs_node *kn;

	if (ino == 0)
		return ERR_PTR(-ESTALE);

	kn = kernfs_find_and_get_node_by_ino(info->root, ino);
	if (!kn)
		return ERR_PTR(-ESTALE);
	inode = kernfs_get_inode(sb, kn);
	kernfs_put(kn);
	if (!inode)
		return ERR_PTR(-ESTALE);

	if (generation && inode->i_generation != generation) {
		/* we didn't find the right inode.. */
		iput(inode);
		return ERR_PTR(-ESTALE);
	}
	return inode;
}

static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
		int fh_len, int fh_type)
{
	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
				    kernfs_fh_get_inode);
}

static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,
		int fh_len, int fh_type)
{
	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
				    kernfs_fh_get_inode);
}

static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
{
	struct kernfs_node *kn = kernfs_dentry_node(child);

	return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
}

static const struct export_operations kernfs_export_ops = {
	.fh_to_dentry	= kernfs_fh_to_dentry,
	.fh_to_parent	= kernfs_fh_to_parent,
	.get_parent	= kernfs_get_parent_dentry,
};

/**
 * kernfs_root_from_sb - determine kernfs_root associated with a super_block
 * @sb: the super_block in question
 *
 * Return the kernfs_root associated with @sb.  If @sb is not a kernfs one,
 * %NULL is returned.
 */
struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
{
	if (sb->s_op == &kernfs_sops)
		return kernfs_info(sb)->root;
	return NULL;
}

/*
 * find the next ancestor in the path down to @child, where @parent was the
 * ancestor whose descendant we want to find.
 *
 * Say the path is /a/b/c/d.  @child is d, @parent is NULL.  We return the root
 * node.  If @parent is b, then we return the node for c.
 * Passing in d as @parent is not ok.
 */
static struct kernfs_node *find_next_ancestor(struct kernfs_node *child,
					      struct kernfs_node *parent)
{
	if (child == parent) {
		pr_crit_once("BUG in find_next_ancestor: called with parent == child");
		return NULL;
	}

	while (child->parent != parent) {
		if (!child->parent)
			return NULL;
		child = child->parent;
	}

	return child;
}

/**
 * kernfs_node_dentry - get a dentry for the given kernfs_node
 * @kn: kernfs_node for which a dentry is needed
 * @sb: the kernfs super_block
 */
struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
				  struct super_block *sb)
{
	struct dentry *dentry;
	struct kernfs_node *knparent = NULL;

	BUG_ON(sb->s_op != &kernfs_sops);

	dentry = dget(sb->s_root);

	/* Check if this is the root kernfs_node */
	if (!kn->parent)
		return dentry;

	knparent = find_next_ancestor(kn, NULL);
	if (WARN_ON(!knparent)) {
		dput(dentry);
		return ERR_PTR(-EINVAL);
	}

	do {
		struct dentry *dtmp;
		struct kernfs_node *kntmp;

		if (kn == knparent)
			return dentry;
		kntmp = find_next_ancestor(kn, knparent);
		if (WARN_ON(!kntmp)) {
			dput(dentry);
			return ERR_PTR(-EINVAL);
		}
		dtmp = lookup_one_len_unlocked(kntmp->name, dentry,
					       strlen(kntmp->name));
		dput(dentry);
		if (IS_ERR(dtmp))
			return dtmp;
		knparent = kntmp;
		dentry = dtmp;
	} while (true);
}

static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc)
{
	struct kernfs_super_info *info = kernfs_info(sb);
	struct inode *inode;
	struct dentry *root;

	info->sb = sb;
	/* Userspace would break if executables or devices appear on sysfs */
	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
	sb->s_blocksize = PAGE_SIZE;
	sb->s_blocksize_bits = PAGE_SHIFT;
	sb->s_magic = kfc->magic;
	sb->s_op = &kernfs_sops;
	sb->s_xattr = kernfs_xattr_handlers;
	if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
		sb->s_export_op = &kernfs_export_ops;
	sb->s_time_gran = 1;

	/* sysfs dentries and inodes don't require IO to create */
	sb->s_shrink.seeks = 0;

	/* get root inode, initialize and unlock it */
	mutex_lock(&kernfs_mutex);
	inode = kernfs_get_inode(sb, info->root->kn);
	mutex_unlock(&kernfs_mutex);
	if (!inode) {
		pr_debug("kernfs: could not get root inode\n");
		return -ENOMEM;
	}

	/* instantiate and link root dentry */
	root = d_make_root(inode);
	if (!root) {
		pr_debug("%s: could not get root dentry!\n", __func__);
		return -ENOMEM;
	}
	sb->s_root = root;
	sb->s_d_op = &kernfs_dops;
	return 0;
}

static int kernfs_test_super(struct super_block *sb, struct fs_context *fc)
{
	struct kernfs_super_info *sb_info = kernfs_info(sb);
	struct kernfs_super_info *info = fc->s_fs_info;

	return sb_info->root == info->root && sb_info->ns == info->ns;
}

static int kernfs_set_super(struct super_block *sb, struct fs_context *fc)
{
	struct kernfs_fs_context *kfc = fc->fs_private;

	kfc->ns_tag = NULL;
	return set_anon_super_fc(sb, fc);
}

/**
 * kernfs_super_ns - determine the namespace tag of a kernfs super_block
 * @sb: super_block of interest
 *
 * Return the namespace tag associated with kernfs super_block @sb.
 */
const void *kernfs_super_ns(struct super_block *sb)
{
	struct kernfs_super_info *info = kernfs_info(sb);

	return info->ns;
}

/**
 * kernfs_get_tree - kernfs filesystem access/retrieval helper
 * @fc: The filesystem context.
 *
 * This is to be called from each kernfs user's fs_context->ops->get_tree()
 * implementation, which should set the specified ->@fs_type and ->@flags, and
 * specify the hierarchy and namespace tag to mount via ->@root and ->@ns,
 * respectively.
 */
int kernfs_get_tree(struct fs_context *fc)
{
	struct kernfs_fs_context *kfc = fc->fs_private;
	struct super_block *sb;
	struct kernfs_super_info *info;
	int error;

	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (!info)
		return -ENOMEM;

	info->root = kfc->root;
	info->ns = kfc->ns_tag;
	INIT_LIST_HEAD(&info->node);

	fc->s_fs_info = info;
	sb = sget_fc(fc, kernfs_test_super, kernfs_set_super);
	if (IS_ERR(sb))
		return PTR_ERR(sb);

	if (!sb->s_root) {
		struct kernfs_super_info *info = kernfs_info(sb);

		kfc->new_sb_created = true;

		error = kernfs_fill_super(sb, kfc);
		if (error) {
			deactivate_locked_super(sb);
			return error;
		}
		sb->s_flags |= SB_ACTIVE;

		mutex_lock(&kernfs_mutex);
		list_add(&info->node, &info->root->supers);
		mutex_unlock(&kernfs_mutex);
	}

	fc->root = dget(sb->s_root);
	return 0;
}

void kernfs_free_fs_context(struct fs_context *fc)
{
	/* Note that we don't deal with kfc->ns_tag here. */
	kfree(fc->s_fs_info);
	fc->s_fs_info = NULL;
}

/**
 * kernfs_kill_sb - kill_sb for kernfs
 * @sb: super_block being killed
 *
 * This can be used directly for file_system_type->kill_sb().  If a kernfs
 * user needs extra cleanup, it can implement its own kill_sb() and call
 * this function at the end.
 */
void kernfs_kill_sb(struct super_block *sb)
{
	struct kernfs_super_info *info = kernfs_info(sb);

	mutex_lock(&kernfs_mutex);
	list_del(&info->node);
	mutex_unlock(&kernfs_mutex);

	/*
	 * Remove the superblock from fs_supers/s_instances
	 * so we can't find it, before freeing kernfs_super_info.
	 */
	kill_anon_super(sb);
	kfree(info);
}

void __init kernfs_init(void)
{

	/*
	 * the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino
	 * can access the slab lock free. This could introduce stale nodes,
	 * please see how kernfs_find_and_get_node_by_ino filters out stale
	 * nodes.
	 */
	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
					      sizeof(struct kernfs_node),
					      0,
					      SLAB_PANIC | SLAB_TYPESAFE_BY_RCU,
					      NULL);

	/* Creates slab cache for kernfs inode attributes */
	kernfs_iattrs_cache  = kmem_cache_create("kernfs_iattrs_cache",
					      sizeof(struct kernfs_iattrs),
					      0, SLAB_PANIC, NULL);
}
Commit	Line	Data
b8441ed2 TH	1	/*
	2	* fs/kernfs/mount.c - kernfs mount implementation
	3	*
	4	* Copyright (c) 2001-3 Patrick Mochel
	5	* Copyright (c) 2007 SUSE Linux Products GmbH
	6	* Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
	7	*
	8	* This file is released under the GPLv2.
	9	*/
fa736a95 TH	10
	11	#include <linux/fs.h>
	12	#include <linux/mount.h>
	13	#include <linux/init.h>
	14	#include <linux/magic.h>
	15	#include <linux/slab.h>
	16	#include <linux/pagemap.h>
fb3c8315	17	#include <linux/namei.h>
4f41fc59	18	#include <linux/seq_file.h>
aa818825	19	#include <linux/exportfs.h>
fa736a95 TH	20
	21	#include "kernfs-internal.h"
	22
26e28d68	23	struct kmem_cache kernfs_node_cache, kernfs_iattrs_cache;
fa736a95	24
6a7fed4e TH	25	static int kernfs_sop_show_options(struct seq_file sf, struct dentry dentry)
6a7fed4e TH	26	{
319ba91d	27	struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry));
6a7fed4e TH	28	struct kernfs_syscall_ops *scops = root->syscall_ops;
	29
	30	if (scops && scops->show_options)
	31	return scops->show_options(sf, root);
	32	return 0;
	33	}
	34
4f41fc59 SH	35	static int kernfs_sop_show_path(struct seq_file sf, struct dentry dentry)
4f41fc59 SH	36	{
319ba91d	37	struct kernfs_node *node = kernfs_dentry_node(dentry);
4f41fc59 SH	38	struct kernfs_root *root = kernfs_root(node);
	39	struct kernfs_syscall_ops *scops = root->syscall_ops;
	40
	41	if (scops && scops->show_path)
	42	return scops->show_path(sf, node, root);
	43
3cc9b23c SH	44	seq_dentry(sf, dentry, " \t\n\\");
3cc9b23c SH	45	return 0;
4f41fc59 SH	46	}
4f41fc59 SH	47
f41c5934	48	const struct super_operations kernfs_sops = {
fa736a95 TH	49	.statfs = simple_statfs,
fa736a95 TH	50	.drop_inode = generic_delete_inode,
c637b8ac	51	.evict_inode = kernfs_evict_inode,
6a7fed4e	52
6a7fed4e	53	.show_options = kernfs_sop_show_options,
4f41fc59	54	.show_path = kernfs_sop_show_path,
fa736a95 TH	55	};
fa736a95 TH	56
69fd5c39 SL	57	/*
	58	* Similar to kernfs_fh_get_inode, this one gets kernfs node from inode
	59	* number and generation
	60	*/
	61	struct kernfs_node kernfs_get_node_by_id(struct kernfs_root root,
	62	const union kernfs_node_id *id)
	63	{
	64	struct kernfs_node *kn;
	65
	66	kn = kernfs_find_and_get_node_by_ino(root, id->ino);
	67	if (!kn)
	68	return NULL;
	69	if (kn->id.generation != id->generation) {
	70	kernfs_put(kn);
	71	return NULL;
	72	}
	73	return kn;
	74	}
	75
aa818825 SL	76	static struct inode kernfs_fh_get_inode(struct super_block sb,
	77	u64 ino, u32 generation)
	78	{
	79	struct kernfs_super_info *info = kernfs_info(sb);
	80	struct inode *inode;
	81	struct kernfs_node *kn;
	82
	83	if (ino == 0)
	84	return ERR_PTR(-ESTALE);
	85
	86	kn = kernfs_find_and_get_node_by_ino(info->root, ino);
	87	if (!kn)
	88	return ERR_PTR(-ESTALE);
	89	inode = kernfs_get_inode(sb, kn);
	90	kernfs_put(kn);
ef13ecbc DC	91	if (!inode)
ef13ecbc DC	92	return ERR_PTR(-ESTALE);
aa818825 SL	93
	94	if (generation && inode->i_generation != generation) {
	95	/* we didn't find the right inode.. */
	96	iput(inode);
	97	return ERR_PTR(-ESTALE);
	98	}
	99	return inode;
	100	}
	101
	102	static struct dentry kernfs_fh_to_dentry(struct super_block sb, struct fid *fid,
	103	int fh_len, int fh_type)
	104	{
	105	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
	106	kernfs_fh_get_inode);
	107	}
	108
	109	static struct dentry kernfs_fh_to_parent(struct super_block sb, struct fid *fid,
	110	int fh_len, int fh_type)
	111	{
	112	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
	113	kernfs_fh_get_inode);
	114	}
	115
	116	static struct dentry kernfs_get_parent_dentry(struct dentry child)
	117	{
	118	struct kernfs_node *kn = kernfs_dentry_node(child);
	119
	120	return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
	121	}
	122
	123	static const struct export_operations kernfs_export_ops = {
	124	.fh_to_dentry = kernfs_fh_to_dentry,
	125	.fh_to_parent = kernfs_fh_to_parent,
	126	.get_parent = kernfs_get_parent_dentry,
	127	};
	128
0c23b225 TH	129	/**
	130	* kernfs_root_from_sb - determine kernfs_root associated with a super_block
	131	* @sb: the super_block in question
	132	*
	133	* Return the kernfs_root associated with @sb. If @sb is not a kernfs one,
	134	* %NULL is returned.
	135	*/
	136	struct kernfs_root kernfs_root_from_sb(struct super_block sb)
	137	{
	138	if (sb->s_op == &kernfs_sops)
	139	return kernfs_info(sb)->root;
	140	return NULL;
	141	}
	142
fb3c8315 AK	143	/*
	144	* find the next ancestor in the path down to @child, where @parent was the
	145	* ancestor whose descendant we want to find.
	146	*
	147	* Say the path is /a/b/c/d. @child is d, @parent is NULL. We return the root
	148	* node. If @parent is b, then we return the node for c.
	149	* Passing in d as @parent is not ok.
	150	*/
	151	static struct kernfs_node find_next_ancestor(struct kernfs_node child,
	152	struct kernfs_node *parent)
	153	{
	154	if (child == parent) {
	155	pr_crit_once("BUG in find_next_ancestor: called with parent == child");
	156	return NULL;
	157	}
	158
	159	while (child->parent != parent) {
	160	if (!child->parent)
	161	return NULL;
	162	child = child->parent;
	163	}
	164
	165	return child;
	166	}
	167
	168	/**
	169	* kernfs_node_dentry - get a dentry for the given kernfs_node
	170	* @kn: kernfs_node for which a dentry is needed
	171	* @sb: the kernfs super_block
	172	*/
	173	struct dentry kernfs_node_dentry(struct kernfs_node kn,
	174	struct super_block *sb)
	175	{
	176	struct dentry *dentry;
	177	struct kernfs_node *knparent = NULL;
	178
	179	BUG_ON(sb->s_op != &kernfs_sops);
	180
	181	dentry = dget(sb->s_root);
	182
	183	/* Check if this is the root kernfs_node */
	184	if (!kn->parent)
	185	return dentry;
	186
	187	knparent = find_next_ancestor(kn, NULL);
399504e2 AV	188	if (WARN_ON(!knparent)) {
399504e2 AV	189	dput(dentry);
fb3c8315	190	return ERR_PTR(-EINVAL);
399504e2	191	}
fb3c8315 AK	192
	193	do {
	194	struct dentry *dtmp;
	195	struct kernfs_node *kntmp;
	196
	197	if (kn == knparent)
	198	return dentry;
	199	kntmp = find_next_ancestor(kn, knparent);
399504e2 AV	200	if (WARN_ON(!kntmp)) {
399504e2 AV	201	dput(dentry);
fb3c8315	202	return ERR_PTR(-EINVAL);
399504e2	203	}
779b8391 AV	204	dtmp = lookup_one_len_unlocked(kntmp->name, dentry,
779b8391 AV	205	strlen(kntmp->name));
fb3c8315 AK	206	dput(dentry);
	207	if (IS_ERR(dtmp))
	208	return dtmp;
	209	knparent = kntmp;
	210	dentry = dtmp;
	211	} while (true);
	212	}
	213
23bf1b6b	214	static int kernfs_fill_super(struct super_block sb, struct kernfs_fs_context kfc)
fa736a95	215	{
c525aadd	216	struct kernfs_super_info *info = kernfs_info(sb);
fa736a95 TH	217	struct inode *inode;
	218	struct dentry *root;
	219
7d568a83	220	info->sb = sb;
a2982cc9 EB	221	/* Userspace would break if executables or devices appear on sysfs */
a2982cc9 EB	222	sb->s_iflags \|= SB_I_NOEXEC \| SB_I_NODEV;
09cbfeaf KS	223	sb->s_blocksize = PAGE_SIZE;
09cbfeaf KS	224	sb->s_blocksize_bits = PAGE_SHIFT;
23bf1b6b	225	sb->s_magic = kfc->magic;
a797bfc3	226	sb->s_op = &kernfs_sops;
e72a1a8b	227	sb->s_xattr = kernfs_xattr_handlers;
aa818825 SL	228	if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
aa818825 SL	229	sb->s_export_op = &kernfs_export_ops;
fa736a95 TH	230	sb->s_time_gran = 1;
fa736a95 TH	231
4b85afbd JW	232	/* sysfs dentries and inodes don't require IO to create */
	233	sb->s_shrink.seeks = 0;
	234
fa736a95	235	/* get root inode, initialize and unlock it */
a797bfc3	236	mutex_lock(&kernfs_mutex);
c637b8ac	237	inode = kernfs_get_inode(sb, info->root->kn);
a797bfc3	238	mutex_unlock(&kernfs_mutex);
fa736a95	239	if (!inode) {
c637b8ac	240	pr_debug("kernfs: could not get root inode\n");
fa736a95 TH	241	return -ENOMEM;
	242	}
	243
	244	/* instantiate and link root dentry */
	245	root = d_make_root(inode);
	246	if (!root) {
	247	pr_debug("%s: could not get root dentry!\n", __func__);
	248	return -ENOMEM;
	249	}
fa736a95	250	sb->s_root = root;
a797bfc3	251	sb->s_d_op = &kernfs_dops;
fa736a95 TH	252	return 0;
	253	}
	254
23bf1b6b	255	static int kernfs_test_super(struct super_block sb, struct fs_context fc)
fa736a95	256	{
c525aadd	257	struct kernfs_super_info *sb_info = kernfs_info(sb);
23bf1b6b	258	struct kernfs_super_info *info = fc->s_fs_info;
fa736a95 TH	259
	260	return sb_info->root == info->root && sb_info->ns == info->ns;
	261	}
	262
23bf1b6b	263	static int kernfs_set_super(struct super_block sb, struct fs_context fc)
fa736a95	264	{
23bf1b6b DH	265	struct kernfs_fs_context *kfc = fc->fs_private;
	266
	267	kfc->ns_tag = NULL;
	268	return set_anon_super_fc(sb, fc);
fa736a95 TH	269	}
	270
	271	/**
	272	* kernfs_super_ns - determine the namespace tag of a kernfs super_block
	273	* @sb: super_block of interest
	274	*
	275	* Return the namespace tag associated with kernfs super_block @sb.
	276	*/
	277	const void kernfs_super_ns(struct super_block sb)
	278	{
c525aadd	279	struct kernfs_super_info *info = kernfs_info(sb);
fa736a95 TH	280
	281	return info->ns;
	282	}
	283
	284	/**
23bf1b6b DH	285	* kernfs_get_tree - kernfs filesystem access/retrieval helper
23bf1b6b DH	286	* @fc: The filesystem context.
fa736a95	287	*
23bf1b6b DH	288	* This is to be called from each kernfs user's fs_context->ops->get_tree()
	289	* implementation, which should set the specified ->@fs_type and ->@flags, and
	290	* specify the hierarchy and namespace tag to mount via ->@root and ->@ns,
	291	* respectively.
fa736a95	292	*/
23bf1b6b	293	int kernfs_get_tree(struct fs_context *fc)
fa736a95	294	{
23bf1b6b	295	struct kernfs_fs_context *kfc = fc->fs_private;
fa736a95	296	struct super_block *sb;
c525aadd	297	struct kernfs_super_info *info;
fa736a95 TH	298	int error;
	299
	300	info = kzalloc(sizeof(*info), GFP_KERNEL);
	301	if (!info)
23bf1b6b	302	return -ENOMEM;
fa736a95	303
23bf1b6b DH	304	info->root = kfc->root;
23bf1b6b DH	305	info->ns = kfc->ns_tag;
82382ace	306	INIT_LIST_HEAD(&info->node);
fa736a95	307
23bf1b6b DH	308	fc->s_fs_info = info;
23bf1b6b DH	309	sb = sget_fc(fc, kernfs_test_super, kernfs_set_super);
fa736a95	310	if (IS_ERR(sb))
23bf1b6b	311	return PTR_ERR(sb);
fed95bab	312
fa736a95	313	if (!sb->s_root) {
7d568a83 TH	314	struct kernfs_super_info *info = kernfs_info(sb);
7d568a83 TH	315
23bf1b6b DH	316	kfc->new_sb_created = true;
	317
	318	error = kernfs_fill_super(sb, kfc);
fa736a95 TH	319	if (error) {
fa736a95 TH	320	deactivate_locked_super(sb);
23bf1b6b	321	return error;
fa736a95	322	}
1751e8a6	323	sb->s_flags \|= SB_ACTIVE;
7d568a83 TH	324
7d568a83 TH	325	mutex_lock(&kernfs_mutex);
23bf1b6b	326	list_add(&info->node, &info->root->supers);
7d568a83	327	mutex_unlock(&kernfs_mutex);
fa736a95 TH	328	}
fa736a95 TH	329
23bf1b6b DH	330	fc->root = dget(sb->s_root);
	331	return 0;
	332	}
	333
	334	void kernfs_free_fs_context(struct fs_context *fc)
	335	{
	336	/* Note that we don't deal with kfc->ns_tag here. */
	337	kfree(fc->s_fs_info);
	338	fc->s_fs_info = NULL;
fa736a95 TH	339	}
	340
	341	/**
	342	* kernfs_kill_sb - kill_sb for kernfs
	343	* @sb: super_block being killed
	344	*
	345	* This can be used directly for file_system_type->kill_sb(). If a kernfs
	346	* user needs extra cleanup, it can implement its own kill_sb() and call
	347	* this function at the end.
	348	*/
	349	void kernfs_kill_sb(struct super_block *sb)
	350	{
c525aadd	351	struct kernfs_super_info *info = kernfs_info(sb);
fa736a95	352
7d568a83 TH	353	mutex_lock(&kernfs_mutex);
	354	list_del(&info->node);
	355	mutex_unlock(&kernfs_mutex);
	356
fa736a95 TH	357	/*
fa736a95 TH	358	* Remove the superblock from fs_supers/s_instances
c525aadd	359	* so we can't find it, before freeing kernfs_super_info.
fa736a95 TH	360	*/
	361	kill_anon_super(sb);
	362	kfree(info);
fa736a95 TH	363	}
	364
	365	void __init kernfs_init(void)
	366	{
ba16b284 SL	367
	368	/*
	369	* the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino
	370	* can access the slab lock free. This could introduce stale nodes,
	371	* please see how kernfs_find_and_get_node_by_ino filters out stale
	372	* nodes.
	373	*/
a797bfc3	374	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
324a56e1	375	sizeof(struct kernfs_node),
ba16b284 SL	376	0,
	377	SLAB_PANIC \| SLAB_TYPESAFE_BY_RCU,
	378	NULL);
26e28d68 AM	379
	380	/* Creates slab cache for kernfs inode attributes */
	381	kernfs_iattrs_cache = kmem_cache_create("kernfs_iattrs_cache",
	382	sizeof(struct kernfs_iattrs),
	383	0, SLAB_PANIC, NULL);
fa736a95	384	}