[linux-2.6-block.git] / fs / sysfs / dir.c

/*
 * dir.c - Operations for sysfs directories.
 */

#undef DEBUG

#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <linux/idr.h>
#include <linux/completion.h>
#include <linux/mutex.h>
#include "sysfs.h"

DEFINE_MUTEX(sysfs_mutex);
spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;

static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
static DEFINE_IDA(sysfs_ino_ida);

/**
 *	sysfs_link_sibling - link sysfs_dirent into sibling list
 *	@sd: sysfs_dirent of interest
 *
 *	Link @sd into its sibling list which starts from
 *	sd->s_parent->s_children.
 *
 *	Locking:
 *	mutex_lock(sysfs_mutex)
 */
static void sysfs_link_sibling(struct sysfs_dirent *sd)
{
	struct sysfs_dirent *parent_sd = sd->s_parent;
	struct sysfs_dirent **pos;

	BUG_ON(sd->s_sibling);

	/* Store directory entries in order by ino.  This allows
	 * readdir to properly restart without having to add a
	 * cursor into the s_children list.
	 */
	for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
		if (sd->s_ino < (*pos)->s_ino)
			break;
	}
	sd->s_sibling = *pos;
	*pos = sd;
}

/**
 *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
 *	@sd: sysfs_dirent of interest
 *
 *	Unlink @sd from its sibling list which starts from
 *	sd->s_parent->s_children.
 *
 *	Locking:
 *	mutex_lock(sysfs_mutex)
 */
static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
{
	struct sysfs_dirent **pos;

	for (pos = &sd->s_parent->s_children; *pos; pos = &(*pos)->s_sibling) {
		if (*pos == sd) {
			*pos = sd->s_sibling;
			sd->s_sibling = NULL;
			break;
		}
	}
}

/**
 *	sysfs_get_dentry - get dentry for the given sysfs_dirent
 *	@sd: sysfs_dirent of interest
 *
 *	Get dentry for @sd.  Dentry is looked up if currently not
 *	present.  This function climbs sysfs_dirent tree till it
 *	reaches a sysfs_dirent with valid dentry attached and descends
 *	down from there looking up dentry for each step.
 *
 *	LOCKING:
 *	Kernel thread context (may sleep)
 *
 *	RETURNS:
 *	Pointer to found dentry on success, ERR_PTR() value on error.
 */
struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
{
	struct sysfs_dirent *cur;
	struct dentry *parent_dentry, *dentry;
	int i, depth;

	/* Find the first parent which has valid s_dentry and get the
	 * dentry.
	 */
	mutex_lock(&sysfs_mutex);
 restart0:
	spin_lock(&sysfs_assoc_lock);
 restart1:
	spin_lock(&dcache_lock);

	dentry = NULL;
	depth = 0;
	cur = sd;
	while (!cur->s_dentry || !cur->s_dentry->d_inode) {
		if (cur->s_flags & SYSFS_FLAG_REMOVED) {
			dentry = ERR_PTR(-ENOENT);
			depth = 0;
			break;
		}
		cur = cur->s_parent;
		depth++;
	}
	if (!IS_ERR(dentry))
		dentry = dget_locked(cur->s_dentry);

	spin_unlock(&dcache_lock);
	spin_unlock(&sysfs_assoc_lock);

	/* from the found dentry, look up depth times */
	while (depth--) {
		/* find and get depth'th ancestor */
		for (cur = sd, i = 0; cur && i < depth; i++)
			cur = cur->s_parent;

		/* This can happen if tree structure was modified due
		 * to move/rename.  Restart.
		 */
		if (i != depth) {
			dput(dentry);
			goto restart0;
		}

		sysfs_get(cur);

		mutex_unlock(&sysfs_mutex);

		/* look it up */
		parent_dentry = dentry;
		mutex_lock(&parent_dentry->d_inode->i_mutex);
		dentry = lookup_one_len_kern(cur->s_name, parent_dentry,
					     strlen(cur->s_name));
		mutex_unlock(&parent_dentry->d_inode->i_mutex);
		dput(parent_dentry);

		if (IS_ERR(dentry)) {
			sysfs_put(cur);
			return dentry;
		}

		mutex_lock(&sysfs_mutex);
		spin_lock(&sysfs_assoc_lock);

		/* This, again, can happen if tree structure has
		 * changed and we looked up the wrong thing.  Restart.
		 */
		if (cur->s_dentry != dentry) {
			dput(dentry);
			sysfs_put(cur);
			goto restart1;
		}

		spin_unlock(&sysfs_assoc_lock);

		sysfs_put(cur);
	}

	mutex_unlock(&sysfs_mutex);
	return dentry;
}

/**
 *	sysfs_get_active - get an active reference to sysfs_dirent
 *	@sd: sysfs_dirent to get an active reference to
 *
 *	Get an active reference of @sd.  This function is noop if @sd
 *	is NULL.
 *
 *	RETURNS:
 *	Pointer to @sd on success, NULL on failure.
 */
struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
{
	if (unlikely(!sd))
		return NULL;

	while (1) {
		int v, t;

		v = atomic_read(&sd->s_active);
		if (unlikely(v < 0))
			return NULL;

		t = atomic_cmpxchg(&sd->s_active, v, v + 1);
		if (likely(t == v))
			return sd;
		if (t < 0)
			return NULL;

		cpu_relax();
	}
}

/**
 *	sysfs_put_active - put an active reference to sysfs_dirent
 *	@sd: sysfs_dirent to put an active reference to
 *
 *	Put an active reference to @sd.  This function is noop if @sd
 *	is NULL.
 */
void sysfs_put_active(struct sysfs_dirent *sd)
{
	struct completion *cmpl;
	int v;

	if (unlikely(!sd))
		return;

	v = atomic_dec_return(&sd->s_active);
	if (likely(v != SD_DEACTIVATED_BIAS))
		return;

	/* atomic_dec_return() is a mb(), we'll always see the updated
	 * sd->s_sibling.
	 */
	cmpl = (void *)sd->s_sibling;
	complete(cmpl);
}

/**
 *	sysfs_get_active_two - get active references to sysfs_dirent and parent
 *	@sd: sysfs_dirent of interest
 *
 *	Get active reference to @sd and its parent.  Parent's active
 *	reference is grabbed first.  This function is noop if @sd is
 *	NULL.
 *
 *	RETURNS:
 *	Pointer to @sd on success, NULL on failure.
 */
struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
{
	if (sd) {
		if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
			return NULL;
		if (unlikely(!sysfs_get_active(sd))) {
			sysfs_put_active(sd->s_parent);
			return NULL;
		}
	}
	return sd;
}

/**
 *	sysfs_put_active_two - put active references to sysfs_dirent and parent
 *	@sd: sysfs_dirent of interest
 *
 *	Put active references to @sd and its parent.  This function is
 *	noop if @sd is NULL.
 */
void sysfs_put_active_two(struct sysfs_dirent *sd)
{
	if (sd) {
		sysfs_put_active(sd);
		sysfs_put_active(sd->s_parent);
	}
}

/**
 *	sysfs_deactivate - deactivate sysfs_dirent
 *	@sd: sysfs_dirent to deactivate
 *
 *	Deny new active references and drain existing ones.
 */
static void sysfs_deactivate(struct sysfs_dirent *sd)
{
	DECLARE_COMPLETION_ONSTACK(wait);
	int v;

	BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
	sd->s_sibling = (void *)&wait;

	/* atomic_add_return() is a mb(), put_active() will always see
	 * the updated sd->s_sibling.
	 */
	v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);

	if (v != SD_DEACTIVATED_BIAS)
		wait_for_completion(&wait);

	sd->s_sibling = NULL;
}

static int sysfs_alloc_ino(ino_t *pino)
{
	int ino, rc;

 retry:
	spin_lock(&sysfs_ino_lock);
	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
	spin_unlock(&sysfs_ino_lock);

	if (rc == -EAGAIN) {
		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
			goto retry;
		rc = -ENOMEM;
	}

	*pino = ino;
	return rc;
}

static void sysfs_free_ino(ino_t ino)
{
	spin_lock(&sysfs_ino_lock);
	ida_remove(&sysfs_ino_ida, ino);
	spin_unlock(&sysfs_ino_lock);
}

void release_sysfs_dirent(struct sysfs_dirent * sd)
{
	struct sysfs_dirent *parent_sd;

 repeat:
	/* Moving/renaming is always done while holding reference.
	 * sd->s_parent won't change beneath us.
	 */
	parent_sd = sd->s_parent;

	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
		sysfs_put(sd->s_elem.symlink.target_sd);
	if (sysfs_type(sd) & SYSFS_COPY_NAME)
		kfree(sd->s_name);
	kfree(sd->s_iattr);
	sysfs_free_ino(sd->s_ino);
	kmem_cache_free(sysfs_dir_cachep, sd);

	sd = parent_sd;
	if (sd && atomic_dec_and_test(&sd->s_count))
		goto repeat;
}

static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
{
	struct sysfs_dirent * sd = dentry->d_fsdata;

	if (sd) {
		/* sd->s_dentry is protected with sysfs_assoc_lock.
		 * This allows sysfs_drop_dentry() to dereference it.
		 */
		spin_lock(&sysfs_assoc_lock);

		/* The dentry might have been deleted or another
		 * lookup could have happened updating sd->s_dentry to
		 * point the new dentry.  Ignore if it isn't pointing
		 * to this dentry.
		 */
		if (sd->s_dentry == dentry)
			sd->s_dentry = NULL;
		spin_unlock(&sysfs_assoc_lock);
		sysfs_put(sd);
	}
	iput(inode);
}

static struct dentry_operations sysfs_dentry_ops = {
	.d_iput		= sysfs_d_iput,
};

struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
{
	char *dup_name = NULL;
	struct sysfs_dirent *sd;

	if (type & SYSFS_COPY_NAME) {
		name = dup_name = kstrdup(name, GFP_KERNEL);
		if (!name)
			return NULL;
	}

	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
	if (!sd)
		goto err_out1;

	if (sysfs_alloc_ino(&sd->s_ino))
		goto err_out2;

	atomic_set(&sd->s_count, 1);
	atomic_set(&sd->s_active, 0);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* dir.c - Operations for sysfs directories.
	3	*/
	4
	5	#undef DEBUG
	6
	7	#include <linux/fs.h>
	8	#include <linux/mount.h>
	9	#include <linux/module.h>
	10	#include <linux/kobject.h>
5f45f1a7	11	#include <linux/namei.h>
2b611bb7	12	#include <linux/idr.h>
8619f979	13	#include <linux/completion.h>
869512ab	14	#include <linux/mutex.h>
1da177e4 LT	15	#include "sysfs.h"
1da177e4 LT	16
3007e997	17	DEFINE_MUTEX(sysfs_mutex);
5f995323	18	spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
1da177e4	19
2b611bb7 TH	20	static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
	21	static DEFINE_IDA(sysfs_ino_ida);
	22
0c73f18b TH	23	/**
	24	* sysfs_link_sibling - link sysfs_dirent into sibling list
	25	* @sd: sysfs_dirent of interest
	26	*
	27	* Link @sd into its sibling list which starts from
	28	* sd->s_parent->s_children.
	29	*
	30	* Locking:
3007e997	31	* mutex_lock(sysfs_mutex)
0c73f18b	32	*/
41fc1c27	33	static void sysfs_link_sibling(struct sysfs_dirent *sd)
0c73f18b TH	34	{
0c73f18b TH	35	struct sysfs_dirent *parent_sd = sd->s_parent;
3efa65b9	36	struct sysfs_dirent **pos;
0c73f18b TH	37
0c73f18b TH	38	BUG_ON(sd->s_sibling);
3efa65b9 EB	39
	40	/* Store directory entries in order by ino. This allows
	41	* readdir to properly restart without having to add a
	42	* cursor into the s_children list.
	43	*/
	44	for (pos = &parent_sd->s_children; pos; pos = &(pos)->s_sibling) {
	45	if (sd->s_ino < (*pos)->s_ino)
	46	break;
	47	}
	48	sd->s_sibling = *pos;
	49	*pos = sd;
0c73f18b TH	50	}
	51
	52	/**
	53	* sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
	54	* @sd: sysfs_dirent of interest
	55	*
	56	* Unlink @sd from its sibling list which starts from
	57	* sd->s_parent->s_children.
	58	*
	59	* Locking:
3007e997	60	* mutex_lock(sysfs_mutex)
0c73f18b	61	*/
41fc1c27	62	static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
0c73f18b TH	63	{
	64	struct sysfs_dirent **pos;
	65
	66	for (pos = &sd->s_parent->s_children; pos; pos = &(pos)->s_sibling) {
	67	if (*pos == sd) {
	68	*pos = sd->s_sibling;
	69	sd->s_sibling = NULL;
	70	break;
	71	}
	72	}
	73	}
	74
53e0ae92 TH	75	/**
	76	* sysfs_get_dentry - get dentry for the given sysfs_dirent
	77	* @sd: sysfs_dirent of interest
	78	*
	79	* Get dentry for @sd. Dentry is looked up if currently not
	80	* present. This function climbs sysfs_dirent tree till it
	81	* reaches a sysfs_dirent with valid dentry attached and descends
	82	* down from there looking up dentry for each step.
	83	*
	84	* LOCKING:
	85	* Kernel thread context (may sleep)
	86	*
	87	* RETURNS:
	88	* Pointer to found dentry on success, ERR_PTR() value on error.
	89	*/
	90	struct dentry sysfs_get_dentry(struct sysfs_dirent sd)
	91	{
	92	struct sysfs_dirent *cur;
	93	struct dentry parent_dentry, dentry;
	94	int i, depth;
	95
	96	/* Find the first parent which has valid s_dentry and get the
	97	* dentry.
	98	*/
	99	mutex_lock(&sysfs_mutex);
	100	restart0:
	101	spin_lock(&sysfs_assoc_lock);
	102	restart1:
	103	spin_lock(&dcache_lock);
	104
	105	dentry = NULL;
	106	depth = 0;
	107	cur = sd;
	108	while (!cur->s_dentry \|\| !cur->s_dentry->d_inode) {
	109	if (cur->s_flags & SYSFS_FLAG_REMOVED) {
	110	dentry = ERR_PTR(-ENOENT);
	111	depth = 0;
	112	break;
	113	}
	114	cur = cur->s_parent;
	115	depth++;
	116	}
	117	if (!IS_ERR(dentry))
	118	dentry = dget_locked(cur->s_dentry);
	119
	120	spin_unlock(&dcache_lock);
	121	spin_unlock(&sysfs_assoc_lock);
	122
	123	/* from the found dentry, look up depth times */
	124	while (depth--) {
	125	/* find and get depth'th ancestor */
	126	for (cur = sd, i = 0; cur && i < depth; i++)
	127	cur = cur->s_parent;
	128
	129	/* This can happen if tree structure was modified due
	130	* to move/rename. Restart.
	131	*/
	132	if (i != depth) {
	133	dput(dentry);
	134	goto restart0;
	135	}
	136
	137	sysfs_get(cur);
	138
139	mutex_unlock(&sysfs_mutex);
140
141	/* look it up */
142	parent_dentry = dentry;
25328026	143	mutex_lock(&parent_dentry->d_inode->i_mutex);
53e0ae92 TH	144	dentry = lookup_one_len_kern(cur->s_name, parent_dentry,
53e0ae92 TH	145	strlen(cur->s_name));
25328026	146	mutex_unlock(&parent_dentry->d_inode->i_mutex);
53e0ae92 TH	147	dput(parent_dentry);
	148
	149	if (IS_ERR(dentry)) {
	150	sysfs_put(cur);
	151	return dentry;
	152	}
	153
	154	mutex_lock(&sysfs_mutex);
	155	spin_lock(&sysfs_assoc_lock);
	156
	157	/* This, again, can happen if tree structure has
	158	* changed and we looked up the wrong thing. Restart.
	159	*/
	160	if (cur->s_dentry != dentry) {
	161	dput(dentry);
	162	sysfs_put(cur);
	163	goto restart1;
	164	}
	165
	166	spin_unlock(&sysfs_assoc_lock);
	167
	168	sysfs_put(cur);
	169	}
	170
	171	mutex_unlock(&sysfs_mutex);
	172	return dentry;
	173	}
	174
b6b4a439 TH	175	/**
	176	* sysfs_get_active - get an active reference to sysfs_dirent
	177	* @sd: sysfs_dirent to get an active reference to
	178	*
	179	* Get an active reference of @sd. This function is noop if @sd
	180	* is NULL.
	181	*
	182	* RETURNS:
	183	* Pointer to @sd on success, NULL on failure.
	184	*/
	185	struct sysfs_dirent sysfs_get_active(struct sysfs_dirent sd)
	186	{
8619f979 TH	187	if (unlikely(!sd))
	188	return NULL;
	189
	190	while (1) {
	191	int v, t;
	192
	193	v = atomic_read(&sd->s_active);
	194	if (unlikely(v < 0))
	195	return NULL;
	196
	197	t = atomic_cmpxchg(&sd->s_active, v, v + 1);
	198	if (likely(t == v))
	199	return sd;
	200	if (t < 0)
	201	return NULL;
	202
	203	cpu_relax();
b6b4a439	204	}
b6b4a439 TH	205	}
	206
	207	/**
	208	* sysfs_put_active - put an active reference to sysfs_dirent
	209	* @sd: sysfs_dirent to put an active reference to
	210	*
	211	* Put an active reference to @sd. This function is noop if @sd
	212	* is NULL.
	213	*/
	214	void sysfs_put_active(struct sysfs_dirent *sd)
	215	{
8619f979 TH	216	struct completion *cmpl;
	217	int v;
	218
	219	if (unlikely(!sd))
	220	return;
	221
	222	v = atomic_dec_return(&sd->s_active);
	223	if (likely(v != SD_DEACTIVATED_BIAS))
	224	return;
	225
	226	/* atomic_dec_return() is a mb(), we'll always see the updated
0c73f18b	227	* sd->s_sibling.
8619f979	228	*/
0c73f18b	229	cmpl = (void *)sd->s_sibling;
8619f979	230	complete(cmpl);
b6b4a439 TH	231	}
	232
	233	/**
	234	* sysfs_get_active_two - get active references to sysfs_dirent and parent
	235	* @sd: sysfs_dirent of interest
	236	*
	237	* Get active reference to @sd and its parent. Parent's active
	238	* reference is grabbed first. This function is noop if @sd is
	239	* NULL.
	240	*
	241	* RETURNS:
	242	* Pointer to @sd on success, NULL on failure.
	243	*/
	244	struct sysfs_dirent sysfs_get_active_two(struct sysfs_dirent sd)
	245	{
	246	if (sd) {
	247	if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
	248	return NULL;
	249	if (unlikely(!sysfs_get_active(sd))) {
	250	sysfs_put_active(sd->s_parent);
	251	return NULL;
	252	}
	253	}
	254	return sd;
	255	}
	256
	257	/**
	258	* sysfs_put_active_two - put active references to sysfs_dirent and parent
	259	* @sd: sysfs_dirent of interest
	260	*
	261	* Put active references to @sd and its parent. This function is
	262	* noop if @sd is NULL.
	263	*/
	264	void sysfs_put_active_two(struct sysfs_dirent *sd)
	265	{
	266	if (sd) {
	267	sysfs_put_active(sd);
	268	sysfs_put_active(sd->s_parent);
	269	}
	270	}
	271
	272	/**
	273	* sysfs_deactivate - deactivate sysfs_dirent
	274	* @sd: sysfs_dirent to deactivate
	275	*
8619f979	276	* Deny new active references and drain existing ones.
b6b4a439	277	*/
fb6896da	278	static void sysfs_deactivate(struct sysfs_dirent *sd)
b6b4a439	279	{
8619f979 TH	280	DECLARE_COMPLETION_ONSTACK(wait);
8619f979 TH	281	int v;
b6b4a439	282
380e6fbb	283	BUG_ON(sd->s_sibling \|\| !(sd->s_flags & SYSFS_FLAG_REMOVED));
0c73f18b	284	sd->s_sibling = (void *)&wait;
8619f979 TH	285
8619f979 TH	286	/* atomic_add_return() is a mb(), put_active() will always see
0c73f18b	287	* the updated sd->s_sibling.
b6b4a439	288	*/
8619f979 TH	289	v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
	290
	291	if (v != SD_DEACTIVATED_BIAS)
	292	wait_for_completion(&wait);
	293
0c73f18b	294	sd->s_sibling = NULL;
b6b4a439 TH	295	}
b6b4a439 TH	296
42b37df6	297	static int sysfs_alloc_ino(ino_t *pino)
2b611bb7 TH	298	{
	299	int ino, rc;
	300
	301	retry:
	302	spin_lock(&sysfs_ino_lock);
	303	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
	304	spin_unlock(&sysfs_ino_lock);
	305
	306	if (rc == -EAGAIN) {
	307	if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
	308	goto retry;
	309	rc = -ENOMEM;
	310	}
	311
	312	*pino = ino;
	313	return rc;
	314	}
	315
	316	static void sysfs_free_ino(ino_t ino)
	317	{
	318	spin_lock(&sysfs_ino_lock);
	319	ida_remove(&sysfs_ino_ida, ino);
	320	spin_unlock(&sysfs_ino_lock);
	321	}
	322
fa7f912a TH	323	void release_sysfs_dirent(struct sysfs_dirent * sd)
fa7f912a TH	324	{
13b3086d TH	325	struct sysfs_dirent *parent_sd;
	326
	327	repeat:
3007e997 TH	328	/* Moving/renaming is always done while holding reference.
	329	* sd->s_parent won't change beneath us.
	330	*/
13b3086d TH	331	parent_sd = sd->s_parent;
13b3086d TH	332
b402d72c	333	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
2b29ac25	334	sysfs_put(sd->s_elem.symlink.target_sd);
b402d72c	335	if (sysfs_type(sd) & SYSFS_COPY_NAME)
0c096b50	336	kfree(sd->s_name);
fa7f912a	337	kfree(sd->s_iattr);
2b611bb7	338	sysfs_free_ino(sd->s_ino);
fa7f912a	339	kmem_cache_free(sysfs_dir_cachep, sd);
13b3086d TH	340
	341	sd = parent_sd;
	342	if (sd && atomic_dec_and_test(&sd->s_count))
	343	goto repeat;
fa7f912a TH	344	}
fa7f912a TH	345
1da177e4 LT	346	static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
	347	{
	348	struct sysfs_dirent * sd = dentry->d_fsdata;
	349
	350	if (sd) {
5f995323 TH	351	/* sd->s_dentry is protected with sysfs_assoc_lock.
5f995323 TH	352	* This allows sysfs_drop_dentry() to dereference it.
dd14cbc9	353	*/
5f995323	354	spin_lock(&sysfs_assoc_lock);
dd14cbc9 TH	355
	356	/* The dentry might have been deleted or another
	357	* lookup could have happened updating sd->s_dentry to
	358	* point the new dentry. Ignore if it isn't pointing
	359	* to this dentry.
	360	*/
	361	if (sd->s_dentry == dentry)
	362	sd->s_dentry = NULL;
5f995323	363	spin_unlock(&sysfs_assoc_lock);
1da177e4 LT	364	sysfs_put(sd);
	365	}
	366	iput(inode);
	367	}
	368
	369	static struct dentry_operations sysfs_dentry_ops = {
	370	.d_iput = sysfs_d_iput,
	371	};
	372
3e519038	373	struct sysfs_dirent sysfs_new_dirent(const char name, umode_t mode, int type)
1da177e4	374	{
0c096b50	375	char *dup_name = NULL;
01da2425	376	struct sysfs_dirent *sd;
0c096b50 TH	377
	378	if (type & SYSFS_COPY_NAME) {
	379	name = dup_name = kstrdup(name, GFP_KERNEL);
	380	if (!name)
01da2425	381	return NULL;
0c096b50	382	}
1da177e4	383
c3762229	384	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
1da177e4	385	if (!sd)
01da2425	386	goto err_out1;
1da177e4	387
0c096b50	388	if (sysfs_alloc_ino(&sd->s_ino))
01da2425	389	goto err_out2;
2b611bb7	390
1da177e4	391	atomic_set(&sd->s_count, 1);
8619f979	392	atomic_set(&sd->s_active, 0);