Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-29 23:51:37 +00:00
Code Issues Packages Projects Releases Wiki Activity
9d9307dabb
linux/fs/sysfs/dir.c
Tejun Heo 0c73f18b7d sysfs: use singly-linked list for sysfs_dirent tree 
Make sysfs_dirent use singly linked list for its tree structure.
sysfs_link_sibling() and sysfs_unlink_sibling() functions are added to
handle simpler cases.  It adds some complexity and cpu cycle overhead
but reduced memory footprint is worthwhile on big machines.

This change reduces the sizeof sysfs_dirent from 104 to 88 on 64bit
and from 60 to 52 on 32bit.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-11 16:09:07 -07:00

939 lines
20 KiB
C
Raw Blame History

/*
* 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 <asm/semaphore.h>
#include "sysfs.h"
DECLARE_RWSEM(sysfs_rename_sem);
spinlock_t sysfs_lock = SPIN_LOCK_UNLOCKED;
spinlock_t kobj_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(sd->s_parent->dentry->d_inode->i_mutex)
*/
static void sysfs_link_sibling(struct sysfs_dirent *sd)
{
struct sysfs_dirent *parent_sd = sd->s_parent;
BUG_ON(sd->s_sibling);
sd->s_sibling = parent_sd->s_children;
parent_sd->s_children = 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(sd->s_parent->dentry->d_inode->i_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_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.
*/
void sysfs_deactivate(struct sysfs_dirent *sd)
{
DECLARE_COMPLETION_ONSTACK(wait);
int v;
BUG_ON(sd->s_sibling);
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:
parent_sd = sd->s_parent;
if (sd->s_type & SYSFS_KOBJ_LINK)
sysfs_put(sd->s_elem.symlink.target_sd);
if (sd->s_type & 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_lock. This
* allows sysfs_drop_dentry() to dereference it.
*/
spin_lock(&sysfs_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_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 = NULL;
if (type & SYSFS_COPY_NAME) {
name = dup_name = kstrdup(name, GFP_KERNEL);
if (!name)
goto err_out;
}
sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
if (!sd)
goto err_out;
if (sysfs_alloc_ino(&sd->s_ino))
goto err_out;
atomic_set(&sd->s_count, 1);
atomic_set(&sd->s_active, 0);
atomic_set(&sd->s_event, 1);
sd->s_name = name;
sd->s_mode = mode;
sd->s_type = type;
return sd;
err_out:
kfree(dup_name);
kmem_cache_free(sysfs_dir_cachep, sd);
return NULL;
}
static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
{
dentry->d_op = &sysfs_dentry_ops;
dentry->d_fsdata = sysfs_get(sd);
/* protect sd->s_dentry against sysfs_d_iput */
spin_lock(&sysfs_lock);
sd->s_dentry = dentry;
spin_unlock(&sysfs_lock);
d_rehash(dentry);
}
void sysfs_attach_dirent(struct sysfs_dirent *sd,
struct sysfs_dirent *parent_sd, struct dentry *dentry)
{
if (dentry)
sysfs_attach_dentry(sd, dentry);
if (parent_sd) {
sd->s_parent = sysfs_get(parent_sd);
sysfs_link_sibling(sd);
}
}
/*
*
* Return -EEXIST if there is already a sysfs element with the same name for
* the same parent.
*
* called with parent inode's i_mutex held
*/
int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
const unsigned char *new)
{
struct sysfs_dirent * sd;
for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
if (sd->s_type) {
if (strcmp(sd->s_name, new))
continue;
else
return -EEXIST;
}
}
return 0;
}
static int create_dir(struct kobject *kobj, struct dentry *parent,
const char *name, struct dentry **p_dentry)
{
int error;
umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
struct dentry *dentry;
struct inode *inode;
struct sysfs_dirent *sd;
mutex_lock(&parent->d_inode->i_mutex);
/* allocate */
dentry = lookup_one_len(name, parent, strlen(name));
if (IS_ERR(dentry)) {
error = PTR_ERR(dentry);
goto out_unlock;
}
error = -EEXIST;
if (dentry->d_inode)
goto out_dput;
error = -ENOMEM;
sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
if (!sd)
goto out_drop;
sd->s_elem.dir.kobj = kobj;
inode = sysfs_get_inode(sd);
if (!inode)
goto out_sput;
if (inode->i_state & I_NEW) {
inode->i_op = &sysfs_dir_inode_operations;
inode->i_fop = &sysfs_dir_operations;
/* directory inodes start off with i_nlink == 2 (for ".") */
inc_nlink(inode);
}
/* link in */
error = -EEXIST;
if (sysfs_dirent_exist(parent->d_fsdata, name))
goto out_iput;
sysfs_instantiate(dentry, inode);
inc_nlink(parent->d_inode);
sysfs_attach_dirent(sd, parent->d_fsdata, dentry);
*p_dentry = dentry;
error = 0;
goto out_unlock; /* pin directory dentry in core */
out_iput:
iput(inode);
out_sput:
sysfs_put(sd);
out_drop:
d_drop(dentry);
out_dput:
dput(dentry);
out_unlock:
mutex_unlock(&parent->d_inode->i_mutex);
return error;
}
int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
{
return create_dir(k,k->dentry,n,d);
}
/**
* sysfs_create_dir - create a directory for an object.
* @kobj: object we're creating directory for.
* @shadow_parent: parent parent object.
*/
int sysfs_create_dir(struct kobject * kobj, struct dentry *shadow_parent)
{
struct dentry * dentry = NULL;
struct dentry * parent;
int error = 0;
BUG_ON(!kobj);
if (shadow_parent)
parent = shadow_parent;
else if (kobj->parent)
parent = kobj->parent->dentry;
else if (sysfs_mount && sysfs_mount->mnt_sb)
parent = sysfs_mount->mnt_sb->s_root;
else
return -EFAULT;
error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
if (!error)
kobj->dentry = dentry;
return error;
}
static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
struct sysfs_dirent * sd;
struct inode *inode;
int found = 0;
for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
if ((sd->s_type & SYSFS_NOT_PINNED) &&
!strcmp(sd->s_name, dentry->d_name.name)) {
found = 1;
break;
}
}
/* no such entry */
if (!found)
return NULL;
/* attach dentry and inode */
inode = sysfs_get_inode(sd);
if (!inode)
return ERR_PTR(-ENOMEM);
if (inode->i_state & I_NEW) {
/* initialize inode according to type */
if (sd->s_type & SYSFS_KOBJ_ATTR) {
inode->i_size = PAGE_SIZE;
inode->i_fop = &sysfs_file_operations;
} else if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
struct bin_attribute *bin_attr =
sd->s_elem.bin_attr.bin_attr;
inode->i_size = bin_attr->size;
inode->i_fop = &bin_fops;
} else if (sd->s_type & SYSFS_KOBJ_LINK)
inode->i_op = &sysfs_symlink_inode_operations;
}
sysfs_instantiate(dentry, inode);
sysfs_attach_dentry(sd, dentry);
return NULL;
}
const struct inode_operations sysfs_dir_inode_operations = {
.lookup = sysfs_lookup,
.setattr = sysfs_setattr,
};
static void remove_dir(struct dentry * d)
{
struct dentry *parent = d->d_parent;
struct sysfs_dirent *sd = d->d_fsdata;
mutex_lock(&parent->d_inode->i_mutex);
sysfs_unlink_sibling(sd);
pr_debug(" o %s removing done (%d)\n",d->d_name.name,
atomic_read(&d->d_count));
mutex_unlock(&parent->d_inode->i_mutex);
sysfs_drop_dentry(sd);
sysfs_deactivate(sd);
sysfs_put(sd);
}
void sysfs_remove_subdir(struct dentry * d)
{
remove_dir(d);
}
static void __sysfs_remove_dir(struct dentry *dentry)
{
struct sysfs_dirent *removed = NULL;
struct sysfs_dirent *parent_sd;
struct sysfs_dirent **pos;
if (!dentry)
return;
pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
mutex_lock(&dentry->d_inode->i_mutex);
parent_sd = dentry->d_fsdata;
pos = &parent_sd->s_children;
while (*pos) {
struct sysfs_dirent *sd = *pos;
if (sd->s_type && (sd->s_type & SYSFS_NOT_PINNED)) {
*pos = sd->s_sibling;
sd->s_sibling = removed;
removed = sd;
} else
pos = &(*pos)->s_sibling;
}
mutex_unlock(&dentry->d_inode->i_mutex);
while (removed) {
struct sysfs_dirent *sd = removed;
removed = sd->s_sibling;
sd->s_sibling = NULL;
sysfs_drop_dentry(sd);
sysfs_deactivate(sd);
sysfs_put(sd);
}
remove_dir(dentry);
}
/**
* sysfs_remove_dir - remove an object's directory.
* @kobj: object.
*
* The only thing special about this is that we remove any files in
* the directory before we remove the directory, and we've inlined
* what used to be sysfs_rmdir() below, instead of calling separately.
*/
void sysfs_remove_dir(struct kobject * kobj)
{
struct dentry *d = kobj->dentry;
spin_lock(&kobj_sysfs_assoc_lock);
kobj->dentry = NULL;
spin_unlock(&kobj_sysfs_assoc_lock);
__sysfs_remove_dir(d);
}
int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
const char *new_name)
{
struct sysfs_dirent *sd = kobj->dentry->d_fsdata;
struct sysfs_dirent *parent_sd = new_parent->d_fsdata;
struct dentry *new_dentry;
char *dup_name;
int error;
if (!new_parent)
return -EFAULT;
down_write(&sysfs_rename_sem);
mutex_lock(&new_parent->d_inode->i_mutex);
new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
if (IS_ERR(new_dentry)) {
error = PTR_ERR(new_dentry);
goto out_unlock;
}
/* By allowing two different directories with the same
* d_parent we allow this routine to move between different
* shadows of the same directory
*/
error = -EINVAL;
if (kobj->dentry->d_parent->d_inode != new_parent->d_inode ||
new_dentry->d_parent->d_inode != new_parent->d_inode ||
new_dentry == kobj->dentry)
goto out_dput;
error = -EEXIST;
if (new_dentry->d_inode)
goto out_dput;
/* rename kobject and sysfs_dirent */
error = -ENOMEM;
new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
if (!new_name)
goto out_drop;
error = kobject_set_name(kobj, "%s", new_name);
if (error)
goto out_free;
kfree(sd->s_name);
sd->s_name = new_name;
/* move under the new parent */
d_add(new_dentry, NULL);
d_move(kobj->dentry, new_dentry);
sysfs_unlink_sibling(sd);
sysfs_get(parent_sd);
sysfs_put(sd->s_parent);
sd->s_parent = parent_sd;
sysfs_link_sibling(sd);
error = 0;
goto out_unlock;
out_free:
kfree(dup_name);
out_drop:
d_drop(new_dentry);
out_dput:
dput(new_dentry);
out_unlock:
mutex_unlock(&new_parent->d_inode->i_mutex);
up_write(&sysfs_rename_sem);
return error;
}
int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
{
struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
struct sysfs_dirent *new_parent_sd, *sd;
int error;
old_parent_dentry = kobj->parent ?
kobj->parent->dentry : sysfs_mount->mnt_sb->s_root;
new_parent_dentry = new_parent ?
new_parent->dentry : sysfs_mount->mnt_sb->s_root;
if (old_parent_dentry->d_inode == new_parent_dentry->d_inode)
return 0; /* nothing to move */
again:
mutex_lock(&old_parent_dentry->d_inode->i_mutex);
if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
goto again;
}
new_parent_sd = new_parent_dentry->d_fsdata;
sd = kobj->dentry->d_fsdata;
new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
strlen(kobj->name));
if (IS_ERR(new_dentry)) {
error = PTR_ERR(new_dentry);
goto out;
} else
error = 0;
d_add(new_dentry, NULL);
d_move(kobj->dentry, new_dentry);
dput(new_dentry);
/* Remove from old parent's list and insert into new parent's list. */
sysfs_unlink_sibling(sd);
sysfs_get(new_parent_sd);
sysfs_put(sd->s_parent);
sd->s_parent = new_parent_sd;
sysfs_link_sibling(sd);
out:
mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
return error;
}
static int sysfs_dir_open(struct inode *inode, struct file *file)
{
struct dentry * dentry = file->f_path.dentry;
struct sysfs_dirent * parent_sd = dentry->d_fsdata;
struct sysfs_dirent * sd;
mutex_lock(&dentry->d_inode->i_mutex);
sd = sysfs_new_dirent("_DIR_", 0, 0);
if (sd)
sysfs_attach_dirent(sd, parent_sd, NULL);
mutex_unlock(&dentry->d_inode->i_mutex);
file->private_data = sd;
return sd ? 0 : -ENOMEM;
}
static int sysfs_dir_close(struct inode *inode, struct file *file)
{
struct dentry * dentry = file->f_path.dentry;
struct sysfs_dirent * cursor = file->private_data;
mutex_lock(&dentry->d_inode->i_mutex);
sysfs_unlink_sibling(cursor);
mutex_unlock(&dentry->d_inode->i_mutex);
release_sysfs_dirent(cursor);
return 0;
}
/* Relationship between s_mode and the DT_xxx types */
static inline unsigned char dt_type(struct sysfs_dirent *sd)
{
return (sd->s_mode >> 12) & 15;
}
static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
struct dentry *dentry = filp->f_path.dentry;
struct sysfs_dirent * parent_sd = dentry->d_fsdata;
struct sysfs_dirent *cursor = filp->private_data;
struct sysfs_dirent **pos;
ino_t ino;
int i = filp->f_pos;
switch (i) {
case 0:
ino = parent_sd->s_ino;
if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
break;
filp->f_pos++;
i++;
/* fallthrough */
case 1:
if (parent_sd->s_parent)
ino = parent_sd->s_parent->s_ino;
else
ino = parent_sd->s_ino;
if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
break;
filp->f_pos++;
i++;
/* fallthrough */
default:
pos = &parent_sd->s_children;
while (*pos != cursor)
pos = &(*pos)->s_sibling;
/* unlink cursor */
*pos = cursor->s_sibling;
if (filp->f_pos == 2)
pos = &parent_sd->s_children;
for ( ; *pos; pos = &(*pos)->s_sibling) {
struct sysfs_dirent *next = *pos;
const char * name;
int len;
if (!next->s_type)
continue;
name = next->s_name;
len = strlen(name);
ino = next->s_ino;
if (filldir(dirent, name, len, filp->f_pos, ino,
dt_type(next)) < 0)
break;
filp->f_pos++;
}
/* put cursor back in */
cursor->s_sibling = *pos;
*pos = cursor;
}
return 0;
}
static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
{
struct dentry * dentry = file->f_path.dentry;
mutex_lock(&dentry->d_inode->i_mutex);
switch (origin) {
case 1:
offset += file->f_pos;
case 0:
if (offset >= 0)
break;
default:
mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
return -EINVAL;
}
if (offset != file->f_pos) {
file->f_pos = offset;
if (file->f_pos >= 2) {
struct sysfs_dirent *sd = dentry->d_fsdata;
struct sysfs_dirent *cursor = file->private_data;
struct sysfs_dirent **pos;
loff_t n = file->f_pos - 2;
sysfs_unlink_sibling(cursor);
pos = &sd->s_children;
while (n && *pos) {
struct sysfs_dirent *next = *pos;
if (next->s_type)
n--;
pos = &(*pos)->s_sibling;
}
cursor->s_sibling = *pos;
*pos = cursor;
}
}
mutex_unlock(&dentry->d_inode->i_mutex);
return offset;
}
/**
* sysfs_make_shadowed_dir - Setup so a directory can be shadowed
* @kobj: object we're creating shadow of.
*/
int sysfs_make_shadowed_dir(struct kobject *kobj,
void * (*follow_link)(struct dentry *, struct nameidata *))
{
struct inode *inode;
struct inode_operations *i_op;
inode = kobj->dentry->d_inode;
if (inode->i_op != &sysfs_dir_inode_operations)
return -EINVAL;
i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
if (!i_op)
return -ENOMEM;
memcpy(i_op, &sysfs_dir_inode_operations, sizeof(*i_op));
i_op->follow_link = follow_link;
/* Locking of inode->i_op?
* Since setting i_op is a single word write and they
* are atomic we should be ok here.
*/
inode->i_op = i_op;
return 0;
}
/**
* sysfs_create_shadow_dir - create a shadow directory for an object.
* @kobj: object we're creating directory for.
*
* sysfs_make_shadowed_dir must already have been called on this
* directory.
*/
struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
{
struct dentry *dir = kobj->dentry;
struct inode *inode = dir->d_inode;
struct dentry *parent = dir->d_parent;
struct sysfs_dirent *parent_sd = parent->d_fsdata;
struct dentry *shadow;
struct sysfs_dirent *sd;
shadow = ERR_PTR(-EINVAL);
if (!sysfs_is_shadowed_inode(inode))
goto out;
shadow = d_alloc(parent, &dir->d_name);
if (!shadow)
goto nomem;
sd = sysfs_new_dirent("_SHADOW_", inode->i_mode, SYSFS_DIR);
if (!sd)
goto nomem;
sd->s_elem.dir.kobj = kobj;
/* point to parent_sd but don't attach to it */
sd->s_parent = sysfs_get(parent_sd);
sysfs_attach_dirent(sd, NULL, shadow);
d_instantiate(shadow, igrab(inode));
inc_nlink(inode);
inc_nlink(parent->d_inode);
dget(shadow); /* Extra count - pin the dentry in core */
out:
return shadow;
nomem:
dput(shadow);
shadow = ERR_PTR(-ENOMEM);
goto out;
}
/**
* sysfs_remove_shadow_dir - remove an object's directory.
* @shadow: dentry of shadow directory
*
* The only thing special about this is that we remove any files in
* the directory before we remove the directory, and we've inlined
* what used to be sysfs_rmdir() below, instead of calling separately.
*/
void sysfs_remove_shadow_dir(struct dentry *shadow)
{
__sysfs_remove_dir(shadow);
}
const struct file_operations sysfs_dir_operations = {
.open = sysfs_dir_open,
.release = sysfs_dir_close,
.llseek = sysfs_dir_lseek,
.read = generic_read_dir,
.readdir = sysfs_readdir,
};
Reference in New Issue View Git Blame Copy Permalink