[PATCH 13/21] sysfs: make sysfs_dirent->s_element a union

From: Tejun Heo
Date: Sat Apr 28 2007 - 09:43:00 EST

Make sd->s_element a union of sysfs_elem_{dir|symlink|attr|bin_attr}
and rename it to s_elem. This is to achieve...

* some level of type checking : changing symlink to point to
sysfs_dirent instead of kobject is much safer and less painful now.
* easier / standardized dereferencing
* allow sysfs_elem_* to contain more than one entry

Where possible, pointer is obtained by directly deferencing from sd
instead of going through other entities. This reduces dependencies to
dentry, inode and kobject. to_attr() and to_bin_attr() are unused now
and removed.

This is in preparation of object reference simplification.

Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
---
fs/sysfs/bin.c | 18 ++++++++++------
fs/sysfs/dir.c | 31 +++++++++++++---------------
fs/sysfs/file.c | 19 +++++++++--------
fs/sysfs/inode.c | 2 +-
fs/sysfs/mount.c | 1 -
fs/sysfs/symlink.c | 23 +++-----------------
fs/sysfs/sysfs.h | 56 ++++++++++++++++++++++++++++-----------------------
7 files changed, 71 insertions(+), 79 deletions(-)

diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index 606267a..67a0d50 100644
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -23,7 +23,8 @@
static int
fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
{
- struct bin_attribute * attr = to_bin_attr(dentry);
+ struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+ struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
struct kobject * kobj = to_kobj(dentry->d_parent);

if (!attr->read)
@@ -65,7 +66,8 @@ read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
static int
flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
{
- struct bin_attribute *attr = to_bin_attr(dentry);
+ struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+ struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
struct kobject *kobj = to_kobj(dentry->d_parent);

if (!attr->write)
@@ -101,9 +103,9 @@ static ssize_t write(struct file *file, const char __user *userbuf,

static int mmap(struct file *file, struct vm_area_struct *vma)
{
- struct dentry *dentry = file->f_path.dentry;
- struct bin_attribute *attr = to_bin_attr(dentry);
- struct kobject *kobj = to_kobj(dentry->d_parent);
+ struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+ struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
+ struct kobject *kobj = to_kobj(file->f_path.dentry->d_parent);

if (!attr->mmap)
return -EINVAL;
@@ -114,7 +116,8 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
static int open(struct inode * inode, struct file * file)
{
struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
- struct bin_attribute * attr = to_bin_attr(file->f_path.dentry);
+ struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+ struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
int error = -EINVAL;

if (!kobj || !attr)
@@ -150,7 +153,8 @@ static int open(struct inode * inode, struct file * file)
static int release(struct inode * inode, struct file * file)
{
struct kobject * kobj = to_kobj(file->f_path.dentry->d_parent);
- struct bin_attribute * attr = to_bin_attr(file->f_path.dentry);
+ struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+ struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
u8 * buffer = file->private_data;

kobject_put(kobj);
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e2ed341..0050de9 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -51,11 +51,8 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
repeat:
parent_sd = sd->s_parent;

- if (sd->s_type & SYSFS_KOBJ_LINK) {
- struct sysfs_symlink * sl = sd->s_element;
- kobject_put(sl->target_kobj);
- kfree(sl);
- }
+ if (sd->s_type & SYSFS_KOBJ_LINK)
+ kobject_put(sd->s_elem.symlink.target_kobj);
if (sd->s_type & SYSFS_COPY_NAME)
kfree(sd->s_name);
kfree(sd->s_iattr);
@@ -83,8 +80,7 @@ static struct dentry_operations sysfs_dentry_ops = {
.d_iput = sysfs_d_iput,
};

-struct sysfs_dirent *sysfs_new_dirent(const char *name, void *element,
- umode_t mode, int type)
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
{
char *dup_name = NULL;
struct sysfs_dirent *sd = NULL;
@@ -108,7 +104,6 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, void *element,
INIT_LIST_HEAD(&sd->s_sibling);

sd->s_name = name;
- sd->s_element = element;
sd->s_mode = mode;
sd->s_type = type;

@@ -148,7 +143,7 @@ int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
struct sysfs_dirent * sd;

list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
- if (sd->s_element) {
+ if (sd->s_type) {
if (strcmp(sd->s_name, new))
continue;
else
@@ -203,9 +198,10 @@ static int create_dir(struct kobject *kobj, struct dentry *parent,
goto out_dput;

error = -ENOMEM;
- sd = sysfs_new_dirent(name, kobj, mode, SYSFS_DIR);
+ sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
if (!sd)
goto out_drop;
+ sd->s_elem.dir.kobj = kobj;
sysfs_attach_dirent(sd, parent->d_fsdata, dentry);

error = sysfs_create(dentry, mode, init_dir);
@@ -278,10 +274,10 @@ static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
int error = 0;

if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
- bin_attr = sd->s_element;
+ bin_attr = sd->s_elem.bin_attr.bin_attr;
attr = &bin_attr->attr;
} else {
- attr = sd->s_element;
+ attr = sd->s_elem.attr.attr;
init = init_file;
}

@@ -386,7 +382,7 @@ static void __sysfs_remove_dir(struct dentry *dentry)
mutex_lock(&dentry->d_inode->i_mutex);
parent_sd = dentry->d_fsdata;
list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
- if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
+ if (!sd->s_type || !(sd->s_type & SYSFS_NOT_PINNED))
continue;
list_del_init(&sd->s_sibling);
sysfs_drop_dentry(sd, dentry);
@@ -538,7 +534,7 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
struct sysfs_dirent * sd;

mutex_lock(&dentry->d_inode->i_mutex);
- sd = sysfs_new_dirent("_DIR_", NULL, 0, 0);
+ sd = sysfs_new_dirent("_DIR_", 0, 0);
if (sd)
sysfs_attach_dirent(sd, parent_sd, NULL);
mutex_unlock(&dentry->d_inode->i_mutex);
@@ -605,7 +601,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)

next = list_entry(p, struct sysfs_dirent,
s_sibling);
- if (!next->s_element)
+ if (!next->s_type)
continue;

name = next->s_name;
@@ -653,7 +649,7 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
struct sysfs_dirent *next;
next = list_entry(p, struct sysfs_dirent,
s_sibling);
- if (next->s_element)
+ if (next->s_type)
n--;
p = p->next;
}
@@ -720,9 +716,10 @@ struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
if (!shadow)
goto nomem;

- sd = sysfs_new_dirent("_SHADOW_", kobj, inode->i_mode, SYSFS_DIR);
+ 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);
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index fe7db4e..b52b4da 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -89,7 +89,6 @@ remove_from_collection(struct sysfs_buffer *buffer, struct inode *node)
static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
{
struct sysfs_dirent * sd = dentry->d_fsdata;
- struct attribute * attr = to_attr(dentry);
struct kobject * kobj = to_kobj(dentry->d_parent);
struct sysfs_ops * ops = buffer->ops;
int ret = 0;
@@ -101,7 +100,7 @@ static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer
return -ENOMEM;

buffer->event = atomic_read(&sd->s_event);
- count = ops->show(kobj,attr,buffer->page);
+ count = ops->show(kobj, sd->s_elem.attr.attr, buffer->page);
BUG_ON(count > (ssize_t)PAGE_SIZE);
if (count >= 0) {
buffer->needs_read_fill = 0;
@@ -229,11 +228,11 @@ fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t
static int
flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
{
- struct attribute * attr = to_attr(dentry);
+ struct sysfs_dirent *attr_sd = dentry->d_fsdata;
struct kobject * kobj = to_kobj(dentry->d_parent);
struct sysfs_ops * ops = buffer->ops;

- return ops->store(kobj,attr,buffer->page,count);
+ return ops->store(kobj, attr_sd->s_elem.attr.attr, buffer->page, count);
}


@@ -278,7 +277,8 @@ out:
static int sysfs_open_file(struct inode *inode, struct file *file)
{
struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
- struct attribute * attr = to_attr(file->f_path.dentry);
+ struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+ struct attribute *attr = attr_sd->s_elem.attr.attr;
struct sysfs_buffer_collection *set;
struct sysfs_buffer * buffer;
struct sysfs_ops * ops = NULL;
@@ -371,15 +371,15 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
static int sysfs_release(struct inode * inode, struct file * filp)
{
struct kobject * kobj = to_kobj(filp->f_path.dentry->d_parent);
- struct attribute * attr = to_attr(filp->f_path.dentry);
- struct module * owner = attr->owner;
+ struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
+ struct attribute *attr = attr_sd->s_elem.attr.attr;
struct sysfs_buffer * buffer = filp->private_data;

if (buffer)
remove_from_collection(buffer, inode);
kobject_put(kobj);
/* After this point, attr should not be accessed. */
- module_put(owner);
+ module_put(attr->owner);

if (buffer) {
if (buffer->page)
@@ -484,11 +484,12 @@ int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
goto out_unlock;
}

- sd = sysfs_new_dirent(attr->name, (void *)attr, mode, type);
+ sd = sysfs_new_dirent(attr->name, mode, type);
if (!sd) {
error = -ENOMEM;
goto out_unlock;
}
+ sd->s_elem.attr.attr = (void *)attr;
sysfs_attach_dirent(sd, parent_sd, NULL);

out_unlock:
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 5d4d32b..9085dc4 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -255,7 +255,7 @@ int sysfs_hash_and_remove(struct dentry * dir, const char * name)
parent_sd = dir->d_fsdata;
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
- if (!sd->s_element)
+ if (!sd->s_type)
continue;
if (!strcmp(sd->s_name, name)) {
list_del_init(&sd->s_sibling);
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index bc613f6..b31256a 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -31,7 +31,6 @@ static struct sysfs_dirent sysfs_root = {
.s_count = ATOMIC_INIT(1),
.s_sibling = LIST_HEAD_INIT(sysfs_root.s_sibling),
.s_children = LIST_HEAD_INIT(sysfs_root.s_children),
- .s_element = NULL,
.s_type = SYSFS_ROOT,
.s_ino = 1,
.s_iattr = NULL,
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index c728204..27df635 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -48,30 +48,15 @@ static void fill_object_path(struct kobject * kobj, char * buffer, int length)
static int sysfs_add_link(struct dentry * parent, const char * name, struct kobject * target)
{
struct sysfs_dirent * parent_sd = parent->d_fsdata;
- struct sysfs_symlink * sl;
struct sysfs_dirent * sd;
- int error;

- error = -ENOMEM;
- sl = kzalloc(sizeof(*sl), GFP_KERNEL);
- if (!sl)
- goto err_out;
-
- sl->target_kobj = kobject_get(target);
-
- sd = sysfs_new_dirent(name, sl, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+ sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
if (!sd)
- goto err_out;
- sysfs_attach_dirent(sd, parent_sd, NULL);
+ return -ENOMEM;

+ sd->s_elem.symlink.target_kobj = kobject_get(target);
+ sysfs_attach_dirent(sd, parent_sd, NULL);
return 0;
-
- err_out:
- if (sl) {
- kobject_put(sl->target_kobj);
- kfree(sl);
- }
- return error;
}

/**
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 9d58b0f..14ca866 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -1,10 +1,33 @@
+struct sysfs_elem_dir {
+ struct kobject * kobj;
+};
+
+struct sysfs_elem_symlink {
+ struct kobject * target_kobj;
+};
+
+struct sysfs_elem_attr {
+ struct attribute * attr;
+};
+
+struct sysfs_elem_bin_attr {
+ struct bin_attribute * bin_attr;
+};
+
struct sysfs_dirent {
atomic_t s_count;
struct sysfs_dirent * s_parent;
struct list_head s_sibling;
struct list_head s_children;
const char * s_name;
- void * s_element;
+
+ union {
+ struct sysfs_elem_dir dir;
+ struct sysfs_elem_symlink symlink;
+ struct sysfs_elem_attr attr;
+ struct sysfs_elem_bin_attr bin_attr;
+ } s_elem;
+
int s_type;
umode_t s_mode;
ino_t s_ino;
@@ -22,8 +45,8 @@ extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));

extern void release_sysfs_dirent(struct sysfs_dirent * sd);
extern int sysfs_dirent_exist(struct sysfs_dirent *, const unsigned char *);
-extern struct sysfs_dirent *sysfs_new_dirent(const char *name, void *element,
- umode_t mode, int type);
+extern struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode,
+ int type);
extern void sysfs_attach_dirent(struct sysfs_dirent *sd,
struct sysfs_dirent *parent_sd,
struct dentry *dentry);
@@ -46,10 +69,6 @@ extern const struct file_operations bin_fops;
extern const struct inode_operations sysfs_dir_inode_operations;
extern const struct inode_operations sysfs_symlink_inode_operations;

-struct sysfs_symlink {
- struct kobject * target_kobj;
-};
-
struct sysfs_buffer {
struct list_head associates;
size_t count;
@@ -69,19 +88,7 @@ struct sysfs_buffer_collection {
static inline struct kobject * to_kobj(struct dentry * dentry)
{
struct sysfs_dirent * sd = dentry->d_fsdata;
- return ((struct kobject *) sd->s_element);
-}
-
-static inline struct attribute * to_attr(struct dentry * dentry)
-{
- struct sysfs_dirent * sd = dentry->d_fsdata;
- return ((struct attribute *) sd->s_element);
-}
-
-static inline struct bin_attribute * to_bin_attr(struct dentry * dentry)
-{
- struct sysfs_dirent * sd = dentry->d_fsdata;
- return ((struct bin_attribute *) sd->s_element);
+ return sd->s_elem.dir.kobj;
}

static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)
@@ -91,11 +98,10 @@ static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)
spin_lock(&dcache_lock);
if (!d_unhashed(dentry)) {
struct sysfs_dirent * sd = dentry->d_fsdata;
- if (sd->s_type & SYSFS_KOBJ_LINK) {
- struct sysfs_symlink * sl = sd->s_element;
- kobj = kobject_get(sl->target_kobj);
- } else
- kobj = kobject_get(sd->s_element);
+ if (sd->s_type & SYSFS_KOBJ_LINK)
+ kobj = kobject_get(sd->s_elem.symlink.target_kobj);
+ else
+ kobj = kobject_get(sd->s_elem.dir.kobj);
}
spin_unlock(&dcache_lock);

--
1.5.0.3


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