sysfs: further localize file creation.

- reanme sysfs_get_inode() to sysfs_create().
- Assume we're using the single sysfs superblock when creating something.
- move file object-specific init commands to callbacks.
- streamline file and directory creation to remove duplicate checks.
- clean up sysfs_fill_super() a bit. 

fs/sysfs/dir.c

@@ -10,16 +10,15 @@
 #include <linux/kobject.h>
 #include "sysfs.h"
 
-static int sysfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+static int init_dir(struct inode * inode)
 {
-	int res;
-	mode = (mode & (S_IRWXUGO|S_ISVTX)) | S_IFDIR;
- 	res = sysfs_mknod(dir, dentry, mode, 0);
- 	if (!res)
- 		dir->i_nlink++;
-	return res;
-}
+	inode->i_op = &simple_dir_inode_operations;
+	inode->i_fop = &simple_dir_operations;
 
+	/* directory inodes start off with i_nlink == 2 (for "." entry) */
+	inode->i_nlink++;
+	return 0;
+}
 
 /**
  *	sysfs_create_dir - create a directory for an object.
@@ -48,8 +47,10 @@ int sysfs_create_dir(struct kobject * kobj)
 	if (!IS_ERR(dentry)) {
 		dentry->d_fsdata = (void *)kobj;
 		kobj->dentry = dentry;
-		error = sysfs_mkdir(parent->d_inode,dentry,
-				    (S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO));
+		error = sysfs_create(dentry,(S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO),
+				     init_dir);
+		if (!error)
+			parent->d_inode->i_nlink++;
 	} else
 		error = PTR_ERR(dentry);
 	up(&parent->d_inode->i_sem);

fs/sysfs/file.c

@@ -8,12 +8,13 @@
 
 #include "sysfs.h"
 
-static int sysfs_create(struct inode *dir, struct dentry *dentry, int mode)
+static struct file_operations sysfs_file_operations;
+
+static int init_file(struct inode * inode)
 {
-	int res;
-	mode = (mode & S_IALLUGO) | S_IFREG;
- 	res = sysfs_mknod(dir, dentry, mode, 0);
-	return res;
+	inode->i_size = PAGE_SIZE;
+	inode->i_fop = &sysfs_file_operations;
+	return 0;
 }
 
 #define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
@@ -325,7 +326,7 @@ static int sysfs_release(struct inode * inode, struct file * filp)
 	return 0;
 }
 
-struct file_operations sysfs_file_operations = {
+static struct file_operations sysfs_file_operations = {
 	.read		= sysfs_read_file,
 	.write		= sysfs_write_file,
 	.llseek		= generic_file_llseek,
@@ -354,7 +355,7 @@ int sysfs_create_file(struct kobject * kobj, struct attribute * attr)
 	dentry = sysfs_get_dentry(parent,attr->name);
 	if (!IS_ERR(dentry)) {
 		dentry->d_fsdata = (void *)attr;
-		error = sysfs_create(parent->d_inode,dentry,attr->mode);
+		error = sysfs_create(dentry,(attr->mode & S_IALLUGO) | S_IFREG,init_file);
 	} else
 		error = PTR_ERR(dentry);
 	up(&parent->d_inode->i_sem);

fs/sysfs/inode.c

@@ -12,7 +12,7 @@
 #include <linux/namei.h>
 #include <linux/backing-dev.h>
 
-extern struct file_operations sysfs_file_operations;
+extern struct super_block * sysfs_sb;
 
 static struct address_space_operations sysfs_aops = {
 	.readpage	= simple_readpage,
@@ -20,17 +20,14 @@ static struct address_space_operations sysfs_aops = {
 	.commit_write	= simple_commit_write
 };
 
-
-
 static struct backing_dev_info sysfs_backing_dev_info = {
 	.ra_pages	= 0,	/* No readahead */
 	.memory_backed	= 1,	/* Does not contribute to dirty memory */
 };
 
-struct inode *sysfs_get_inode(struct super_block *sb, int mode, int dev)
+struct inode * sysfs_new_inode(mode_t mode)
 {
-	struct inode *inode = new_inode(sb);
-
+	struct inode * inode = new_inode(sysfs_sb);
 	if (inode) {
 		inode->i_mode = mode;
 		inode->i_uid = current->fsuid;
@@ -41,46 +38,44 @@ struct inode *sysfs_get_inode(struct super_block *sb, int mode, int dev)
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		inode->i_mapping->a_ops = &sysfs_aops;
 		inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
-		switch (mode & S_IFMT) {
-		default:
-			init_special_inode(inode, mode, dev);
-			break;
-		case S_IFREG:
-			inode->i_size = PAGE_SIZE;
-			inode->i_fop = &sysfs_file_operations;
-			break;
-		case S_IFDIR:
-			inode->i_op = &simple_dir_inode_operations;
-			inode->i_fop = &simple_dir_operations;
-
-			/* directory inodes start off with i_nlink == 2 (for "." entry) */
-			inode->i_nlink++;
-			break;
-		case S_IFLNK:
-			inode->i_op = &page_symlink_inode_operations;
-			break;
-		}
 	}
 	return inode;
 }
 
-int sysfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 {
-	struct inode *inode;
 	int error = 0;
-
-	if (!dentry->d_inode) {
-		inode = sysfs_get_inode(dir->i_sb, mode, dev);
-		if (inode) {
-			d_instantiate(dentry, inode);
-			dget(dentry);
+	struct inode * inode = NULL;
+
+	if (dentry) {
+		if (!dentry->d_inode) {
+			if ((inode = sysfs_new_inode(mode)))
+				goto Proceed;
+			else 
+				error = -ENOMEM;
 		} else
-			error = -ENOSPC;
+			error = -EEXIST;
+	} else 
+		error = -ENOENT;
+	goto Done;
+
+ Proceed:
+	if (init)
+		error = init(inode);
+	if (!error) {
+		d_instantiate(dentry, inode);
+		dget(dentry);
 	} else
-		error = -EEXIST;
+		iput(inode);
+ Done:
 	return error;
 }
 
+int sysfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+{
+	return sysfs_create(dentry, mode, NULL);
+}
+
 struct dentry * sysfs_get_dentry(struct dentry * parent, const char * name)
 {
 	struct qstr qstr;

fs/sysfs/mount.c

@@ -2,6 +2,8 @@
  * mount.c - operations for initializing and mounting sysfs.
  */
 
+#define DEBUG 
+
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/pagemap.h>
@@ -12,6 +14,7 @@
 #define SYSFS_MAGIC 0x62656572
 
 struct vfsmount *sysfs_mount;
+struct super_block * sysfs_sb = NULL;
 
 static struct super_operations sysfs_ops = {
 	.statfs		= simple_statfs,
@@ -27,10 +30,16 @@ static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 	sb->s_magic = SYSFS_MAGIC;
 	sb->s_op = &sysfs_ops;
-	inode = sysfs_get_inode(sb, S_IFDIR | 0755, 0);
+	sysfs_sb = sb;
 
-	if (!inode) {
-		pr_debug("%s: could not get inode!\n",__FUNCTION__);
+	inode = sysfs_new_inode(S_IFDIR | S_IRUGO | S_IWUSR);
+	if (inode) {
+		inode->i_op = &simple_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
+		/* directory inodes start off with i_nlink == 2 (for "." entry) */
+		inode->i_nlink++;	
+	} else {
+		pr_debug("sysfs: could not get root inode\n");
 		return -ENOMEM;
 	}
 

fs/sysfs/symlink.c

@@ -9,23 +9,22 @@
 #include "sysfs.h"
 
 
-static int sysfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
+static int init_symlink(struct inode * inode)
 {
-	struct inode *inode;
-	int error = -ENOSPC;
+	inode->i_op = &page_symlink_inode_operations;
+	return 0;
+}
 
-	if (dentry->d_inode)
-		return -EEXIST;
+static int sysfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
+{
+	int error;
 
-	inode = sysfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
-	if (inode) {
+	error = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
+	if (!error) {
 		int l = strlen(symname)+1;
-		error = page_symlink(inode, symname, l);
-		if (!error) {
-			d_instantiate(dentry, inode);
-			dget(dentry);
-		} else
-			iput(inode);
+		error = page_symlink(dentry->d_inode, symname, l);
+		if (error)
+			iput(dentry->d_inode);
 	}
 	return error;
 }

fs/sysfs/sysfs.h

 
 extern struct vfsmount * sysfs_mount;
 
-extern struct inode *sysfs_get_inode(struct super_block *sb, int mode, int dev);
-
-extern int sysfs_mknod(struct inode *, struct dentry *, int, dev_t);
+extern struct inode * sysfs_new_inode(mode_t mode);
+extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));
 
 extern struct dentry * sysfs_get_dentry(struct dentry *, char *);