[PATCH 1/5] Add sysfs_dirent to sysfs dentry

From: Maneesh Soni
Date: Thu Jul 29 2004 - 15:42:27 EST



o This the first patch in the series of patches implementing sysfs backing
store. It introduces the new sysfs_dirent data structure. The sysfs_dirent
is added to each of the element which can be represented in sysfs like,
kobject (directory), text or binary attributes (files), attribute groups
(directory) and symlinks.

o It uses dentry's d_fsdata field to attach the corresponding sysfs_dirent.

o The sysfs_dirents are maintained in a tree of all the sysfs entries using the
s_children and s_sibling list pointers.

o The patch just adds the sysfs_dirent structure and hence should not be used
independently but system can boot with it.


fs/sysfs/bin.c | 17 +++++++++++----
fs/sysfs/dir.c | 27 +++++++++++++++++++-----
fs/sysfs/file.c | 25 ++++++++++++++++------
fs/sysfs/group.c | 2 -
fs/sysfs/mount.c | 8 +++++++
fs/sysfs/symlink.c | 56 +++++++++++++++++++++++++++++++++++++++++++++-----
fs/sysfs/sysfs.h | 37 ++++++++++++++++++++++++++++++---
include/linux/sysfs.h | 21 ++++++++++++++++++
8 files changed, 169 insertions(+), 24 deletions(-)

diff -puN include/linux/sysfs.h~sysfs-backing-store-add-sysfs_dirent include/linux/sysfs.h
--- linux-2.6.8-rc2-mm1/include/linux/sysfs.h~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/include/linux/sysfs.h 2004-07-29 15:30:37.000000000 -0500
@@ -9,6 +9,8 @@
#ifndef _SYSFS_H_
#define _SYSFS_H_

+#include <asm/atomic.h>
+
struct kobject;
struct module;

@@ -57,6 +59,25 @@ struct sysfs_ops {
ssize_t (*store)(struct kobject *,struct attribute *,const char *, size_t);
};

+struct sysfs_dirent {
+ atomic_t s_count;
+ struct list_head s_sibling;
+ struct list_head s_children;
+ void * s_element;
+ int s_type;
+ umode_t s_mode;
+ struct dentry * s_dentry;
+};
+
+#define SYSFS_ROOT 0x0001
+#define SYSFS_KOBJECT 0x0002
+#define SYSFS_KOBJ_ATTR 0x0004
+#define SYSFS_KOBJ_BIN_ATTR 0x0008
+#define SYSFS_KOBJ_ATTR_GROUP 0x0010
+#define SYSFS_KOBJ_LINK 0x0020
+#define SYSFS_NOT_PINNED (SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
+
+
#ifdef CONFIG_SYSFS

extern int
diff -puN fs/sysfs/dir.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/dir.c
--- linux-2.6.8-rc2-mm1/fs/sysfs/dir.c~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/fs/sysfs/dir.c 2004-07-29 15:31:16.000000000 -0500
@@ -27,17 +27,34 @@ static int create_dir(struct kobject * k
const char * n, struct dentry ** d)
{
int error;
+ umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;

down(&p->d_inode->i_sem);
*d = sysfs_get_dentry(p,n);
if (!IS_ERR(*d)) {
- error = sysfs_create(*d,
- S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO,
- init_dir);
+ error = sysfs_create(*d, mode, init_dir);
if (!error) {
- (*d)->d_fsdata = k;
- p->d_inode->i_nlink++;
+ struct sysfs_dirent * sd, * parent_sd;
+ parent_sd = p->d_fsdata;
+ sd = sysfs_new_dirent(parent_sd, k,
+ (parent_sd->s_element == k) ?
+ SYSFS_KOBJ_ATTR_GROUP :
+ SYSFS_KOBJECT);
+ if (sd) {
+ (*d)->d_fsdata = sd;
+ p->d_inode->i_nlink++;
+ sd->s_dentry = *d;
+ sd->s_mode = mode;
+ } else {
+ /* error, release the ref taken in
+ * sysfs_create()
+ */
+ dput(*d);
+ error = -ENOMEM;
+ }
}
+ /* This will free the dentry in case of error
+ */
dput(*d);
} else
error = PTR_ERR(*d);
diff -puN fs/sysfs/file.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/file.c
--- linux-2.6.8-rc2-mm1/fs/sysfs/file.c~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/fs/sysfs/file.c 2004-07-29 15:31:10.000000000 -0500
@@ -346,10 +346,12 @@ static struct file_operations sysfs_file
};


-int sysfs_add_file(struct dentry * dir, const struct attribute * attr)
+int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
{
struct dentry * dentry;
- int error;
+ struct sysfs_dirent * sd;
+ struct sysfs_dirent * parent_sd = dir->d_fsdata;
+ int error = 0;

down(&dir->d_inode->i_sem);
dentry = sysfs_get_dentry(dir,attr->name);
@@ -357,8 +359,18 @@ int sysfs_add_file(struct dentry * dir,
error = sysfs_create(dentry,
(attr->mode & S_IALLUGO) | S_IFREG,
init_file);
- if (!error)
- dentry->d_fsdata = (void *)attr;
+ if (!error) {
+
+ sd = sysfs_new_dirent(parent_sd, (void *) attr, type);
+ if (sd) {
+ sd->s_mode = (attr->mode & S_IALLUGO) | S_IFREG;
+ dentry->d_fsdata = sd;
+ sd->s_dentry = dentry;
+ } else {
+ dput(dentry);
+ error = -ENOMEM;
+ }
+ }
dput(dentry);
} else
error = PTR_ERR(dentry);
@@ -375,8 +387,9 @@ int sysfs_add_file(struct dentry * dir,

int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
{
- if (kobj && attr)
- return sysfs_add_file(kobj->dentry,attr);
+ if (kobj && kobj->dentry && attr)
+ return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
+
return -EINVAL;
}

diff -puN fs/sysfs/bin.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/bin.c
--- linux-2.6.8-rc2-mm1/fs/sysfs/bin.c~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/fs/sysfs/bin.c 2004-07-29 15:31:10.000000000 -0500
@@ -160,6 +160,8 @@ int sysfs_create_bin_file(struct kobject
{
struct dentry * dentry;
struct dentry * parent;
+ struct sysfs_dirent * sd;
+ umode_t mode = (attr->attr.mode & S_IALLUGO) | S_IFREG;
int error = 0;

if (!kobj || !attr)
@@ -170,13 +172,20 @@ int sysfs_create_bin_file(struct kobject
down(&parent->d_inode->i_sem);
dentry = sysfs_get_dentry(parent,attr->attr.name);
if (!IS_ERR(dentry)) {
- dentry->d_fsdata = (void *)attr;
- error = sysfs_create(dentry,
- (attr->attr.mode & S_IALLUGO) | S_IFREG,
- NULL);
+ error = sysfs_create(dentry, mode, NULL);
if (!error) {
dentry->d_inode->i_size = attr->size;
dentry->d_inode->i_fop = &bin_fops;
+ sd = sysfs_new_dirent(parent->d_fsdata, (void *) attr,
+ SYSFS_KOBJ_BIN_ATTR);
+ if (!sd) {
+ sd->s_mode = mode;
+ dentry->d_fsdata = sd;
+ sd->s_dentry = dentry;
+ } else {
+ dput(dentry);
+ error = -ENOMEM;
+ }
}
dput(dentry);
} else
diff -puN fs/sysfs/sysfs.h~sysfs-backing-store-add-sysfs_dirent fs/sysfs/sysfs.h
--- linux-2.6.8-rc2-mm1/fs/sysfs/sysfs.h~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/fs/sysfs/sysfs.h 2004-07-29 15:31:16.000000000 -0500
@@ -5,8 +5,9 @@ extern struct inode * sysfs_new_inode(mo
extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));

extern struct dentry * sysfs_get_dentry(struct dentry *, const char *);
+extern void sysfs_drop_dentry(struct sysfs_dirent *, struct dentry *);

-extern int sysfs_add_file(struct dentry * dir, const struct attribute * attr);
+extern int sysfs_add_file(struct dentry *, const struct attribute *, int);
extern void sysfs_hash_and_remove(struct dentry * dir, const char * name);

extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **);
@@ -16,14 +17,44 @@ extern int sysfs_readlink(struct dentry
extern int sysfs_follow_link(struct dentry *, struct nameidata *);
extern struct rw_semaphore sysfs_rename_sem;

+struct sysfs_symlink {
+ char * link_name;
+ struct kobject * target_kobj;
+};
+
static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)
{
struct kobject * kobj = NULL;

spin_lock(&dcache_lock);
- if (!d_unhashed(dentry))
- kobj = kobject_get(dentry->d_fsdata);
+ 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);
+ }
spin_unlock(&dcache_lock);

return kobj;
}
+
+static inline
+struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent * p, void * e, int t)
+{
+ struct sysfs_dirent * sd;
+
+ sd = kmalloc(sizeof(*sd), GFP_KERNEL);
+ if (!sd)
+ return NULL;
+ memset(sd, 0, sizeof(*sd));
+ atomic_set(&sd->s_count, 1);
+ sd->s_element = e;
+ sd->s_type = t;
+ sd->s_dentry = NULL;
+ INIT_LIST_HEAD(&sd->s_children);
+ list_add(&sd->s_sibling, &p->s_children);
+
+ return sd;
+}
diff -puN fs/sysfs/group.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/group.c
--- linux-2.6.8-rc2-mm1/fs/sysfs/group.c~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/fs/sysfs/group.c 2004-07-29 15:30:37.000000000 -0500
@@ -31,7 +31,7 @@ static int create_files(struct dentry *
int error = 0;

for (attr = grp->attrs; *attr && !error; attr++) {
- error = sysfs_add_file(dir,*attr);
+ error = sysfs_add_file(dir, *attr, SYSFS_KOBJ_ATTR);
}
if (error)
remove_files(dir,grp);
diff -puN fs/sysfs/symlink.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/symlink.c
--- linux-2.6.8-rc2-mm1/fs/sysfs/symlink.c~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/fs/sysfs/symlink.c 2004-07-29 15:31:07.000000000 -0500
@@ -53,6 +53,39 @@ static void fill_object_path(struct kobj
}
}

+static struct sysfs_dirent *
+sysfs_add_link(struct sysfs_dirent * parent_sd, char * name,
+ struct kobject * target)
+{
+ struct sysfs_dirent * sd;
+ struct sysfs_symlink * sl;
+ int error = 0;
+
+ error = -ENOMEM;
+ sl = kmalloc(sizeof(*sl), GFP_KERNEL);
+ if (!sl)
+ goto exit1;
+
+ sl->link_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
+ if (!sl->link_name)
+ goto exit2;
+
+ strcpy(sl->link_name, name);
+ sl->target_kobj = kobject_get(target);
+
+ sd = sysfs_new_dirent(parent_sd, sl, SYSFS_KOBJ_LINK);
+ if (sd) {
+ sd->s_mode = S_IFLNK|S_IRWXUGO;
+ return sd;
+ }
+
+ kfree(sl->link_name);
+exit2:
+ kfree(sl);
+exit1:
+ return ERR_PTR(error);
+}
+
/**
* sysfs_create_link - create symlink between two objects.
* @kobj: object whose directory we're creating the link in.
@@ -65,15 +98,28 @@ int sysfs_create_link(struct kobject * k
struct dentry * d;
int error = 0;

+ if (!name)
+ return -EINVAL;
+
down(&dentry->d_inode->i_sem);
d = sysfs_get_dentry(dentry,name);
if (!IS_ERR(d)) {
error = sysfs_create(d, S_IFLNK|S_IRWXUGO, init_symlink);
- if (!error)
- /*
- * associate the link dentry with the target kobject
- */
- d->d_fsdata = kobject_get(target);
+ if (!error) {
+ struct sysfs_dirent * sd;
+ sd = sysfs_add_link(dentry->d_fsdata, name, target);
+ if (!IS_ERR(sd)) {
+ /*
+ * associate the link dentry with the target
+ * through the corresponding sysfs_dirent.
+ */
+ d->d_fsdata = sd;
+ sd->s_dentry = dentry;
+ } else {
+ dput(d);
+ error = PTR_ERR(sd);
+ }
+ }
dput(d);
} else
error = PTR_ERR(d);
diff -puN fs/sysfs/mount.c~sysfs-backing-store-add-sysfs_dirent fs/sysfs/mount.c
--- linux-2.6.8-rc2-mm1/fs/sysfs/mount.c~sysfs-backing-store-add-sysfs_dirent 2004-07-29 15:30:37.000000000 -0500
+++ linux-2.6.8-rc2-mm1-maneesh/fs/sysfs/mount.c 2004-07-29 15:31:16.000000000 -0500
@@ -22,6 +22,13 @@ static struct super_operations sysfs_ops
.drop_inode = generic_delete_inode,
};

+struct sysfs_dirent sysfs_root = {
+ .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,
+};
+
static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
@@ -50,6 +57,7 @@ static int sysfs_fill_super(struct super
iput(inode);
return -ENOMEM;
}
+ root->d_fsdata = &sysfs_root;
sb->s_root = root;
return 0;
}

_
--
Maneesh Soni
Linux Technology Center,
IBM Austin
email: maneesh@xxxxxxxxxx
Phone: 1-512-838-1896 Fax:
T/L : 6781896
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