[mirror_ubuntu-bionic-kernel.git] / fs / ramfs / inode.c

/*
 * Resizable simple ram filesystem for Linux.
 *
 * Copyright (C) 2000 Linus Torvalds.
 *               2000 Transmeta Corp.
 *
 * Usage limits added by David Gibson, Linuxcare Australia.
 * This file is released under the GPL.
 */

/*
 * NOTE! This filesystem is probably most useful
 * not as a real filesystem, but as an example of
 * how virtual filesystems can be written.
 *
 * It doesn't get much simpler than this. Consider
 * that this file implements the full semantics of
 * a POSIX-compliant read-write filesystem.
 *
 * Note in particular how the filesystem does not
 * need to implement any data structures of its own
 * to keep track of the virtual data: using the VFS
 * caches is sufficient.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
#include <linux/backing-dev.h>
#include <linux/ramfs.h>

#include <asm/uaccess.h>
#include "internal.h"

/* some random number */
#define RAMFS_MAGIC	0x858458f6

static struct super_operations ramfs_ops;
static struct inode_operations ramfs_dir_inode_operations;

static struct backing_dev_info ramfs_backing_dev_info = {
	.ra_pages	= 0,	/* No readahead */
	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK |
			  BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
			  BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
};

struct inode *ramfs_get_inode(struct super_block *sb, int mode, dev_t dev)
{
	struct inode * inode = new_inode(sb);

	if (inode) {
		inode->i_mode = mode;
		inode->i_uid = current->fsuid;
		inode->i_gid = current->fsgid;
		inode->i_blksize = PAGE_CACHE_SIZE;
		inode->i_blocks = 0;
		inode->i_mapping->a_ops = &ramfs_aops;
		inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
		switch (mode & S_IFMT) {
		default:
			init_special_inode(inode, mode, dev);
			break;
		case S_IFREG:
			inode->i_op = &ramfs_file_inode_operations;
			inode->i_fop = &ramfs_file_operations;
			break;
		case S_IFDIR:
			inode->i_op = &ramfs_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;
}

/*
 * File creation. Allocate an inode, and we're done..
 */
/* SMP-safe */
static int
ramfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
	struct inode * inode = ramfs_get_inode(dir->i_sb, mode, dev);
	int error = -ENOSPC;

	if (inode) {
		if (dir->i_mode & S_ISGID) {
			inode->i_gid = dir->i_gid;
			if (S_ISDIR(mode))
				inode->i_mode |= S_ISGID;
		}
		d_instantiate(dentry, inode);
		dget(dentry);	/* Extra count - pin the dentry in core */
		error = 0;
	}
	return error;
}

static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
{
	int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
	if (!retval)
		dir->i_nlink++;
	return retval;
}

static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
{
	return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
}

static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
{
	struct inode *inode;
	int error = -ENOSPC;

	inode = ramfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
	if (inode) {
		int l = strlen(symname)+1;
		error = page_symlink(inode, symname, l);
		if (!error) {
			if (dir->i_mode & S_ISGID)
				inode->i_gid = dir->i_gid;
			d_instantiate(dentry, inode);
			dget(dentry);
		} else
			iput(inode);
	}
	return error;
}

static struct inode_operations ramfs_dir_inode_operations = {
	.create		= ramfs_create,
	.lookup		= simple_lookup,
	.link		= simple_link,
	.unlink		= simple_unlink,
	.symlink	= ramfs_symlink,
	.mkdir		= ramfs_mkdir,
	.rmdir		= simple_rmdir,
	.mknod		= ramfs_mknod,
	.rename		= simple_rename,
};

static struct super_operations ramfs_ops = {
	.statfs		= simple_statfs,
	.drop_inode	= generic_delete_inode,
};

static int ramfs_fill_super(struct super_block * sb, void * data, int silent)
{
	struct inode * inode;
	struct dentry * root;

	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = RAMFS_MAGIC;
	sb->s_op = &ramfs_ops;
	sb->s_time_gran = 1;
	inode = ramfs_get_inode(sb, S_IFDIR | 0755, 0);
	if (!inode)
		return -ENOMEM;

	root = d_alloc_root(inode);
	if (!root) {
		iput(inode);
		return -ENOMEM;
	}
	sb->s_root = root;
	return 0;
}

struct super_block *ramfs_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return get_sb_nodev(fs_type, flags, data, ramfs_fill_super);
}

static struct super_block *rootfs_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return get_sb_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super);
}

static struct file_system_type ramfs_fs_type = {
	.name		= "ramfs",
	.get_sb		= ramfs_get_sb,
	.kill_sb	= kill_litter_super,
};
static struct file_system_type rootfs_fs_type = {
	.name		= "rootfs",
	.get_sb		= rootfs_get_sb,
	.kill_sb	= kill_litter_super,
};

static int __init init_ramfs_fs(void)
{
	return register_filesystem(&ramfs_fs_type);
}

static void __exit exit_ramfs_fs(void)
{
	unregister_filesystem(&ramfs_fs_type);
}

module_init(init_ramfs_fs)
module_exit(exit_ramfs_fs)

int __init init_rootfs(void)
{
	return register_filesystem(&rootfs_fs_type);
}

MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Resizable simple ram filesystem for Linux.
	3	*
	4	* Copyright (C) 2000 Linus Torvalds.
	5	* 2000 Transmeta Corp.
	6	*
	7	* Usage limits added by David Gibson, Linuxcare Australia.
	8	* This file is released under the GPL.
	9	*/
	10
	11	/*
	12	* NOTE! This filesystem is probably most useful
	13	* not as a real filesystem, but as an example of
	14	* how virtual filesystems can be written.
	15	*
	16	* It doesn't get much simpler than this. Consider
	17	* that this file implements the full semantics of
	18	* a POSIX-compliant read-write filesystem.
	19	*
	20	* Note in particular how the filesystem does not
	21	* need to implement any data structures of its own
	22	* to keep track of the virtual data: using the VFS
	23	* caches is sufficient.
	24	*/
	25
	26	#include <linux/module.h>
	27	#include <linux/fs.h>
	28	#include <linux/pagemap.h>
	29	#include <linux/highmem.h>
	30	#include <linux/init.h>
	31	#include <linux/string.h>
	32	#include <linux/smp_lock.h>
	33	#include <linux/backing-dev.h>
	34	#include <linux/ramfs.h>
	35
	36	#include <asm/uaccess.h>
642fb4d1	37	#include "internal.h"
1da177e4 LT	38
	39	/* some random number */
	40	#define RAMFS_MAGIC 0x858458f6
	41
	42	static struct super_operations ramfs_ops;
1da177e4 LT	43	static struct inode_operations ramfs_dir_inode_operations;
	44
	45	static struct backing_dev_info ramfs_backing_dev_info = {
	46	.ra_pages = 0, /* No readahead */
	47	.capabilities = BDI_CAP_NO_ACCT_DIRTY \| BDI_CAP_NO_WRITEBACK \|
	48	BDI_CAP_MAP_DIRECT \| BDI_CAP_MAP_COPY \|
	49	BDI_CAP_READ_MAP \| BDI_CAP_WRITE_MAP \| BDI_CAP_EXEC_MAP,
	50	};
	51
	52	struct inode ramfs_get_inode(struct super_block sb, int mode, dev_t dev)
	53	{
	54	struct inode * inode = new_inode(sb);
	55
	56	if (inode) {
	57	inode->i_mode = mode;
	58	inode->i_uid = current->fsuid;
	59	inode->i_gid = current->fsgid;
	60	inode->i_blksize = PAGE_CACHE_SIZE;
	61	inode->i_blocks = 0;
	62	inode->i_mapping->a_ops = &ramfs_aops;
	63	inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
	64	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	65	switch (mode & S_IFMT) {
	66	default:
	67	init_special_inode(inode, mode, dev);
	68	break;
	69	case S_IFREG:
	70	inode->i_op = &ramfs_file_inode_operations;
	71	inode->i_fop = &ramfs_file_operations;
	72	break;
	73	case S_IFDIR:
	74	inode->i_op = &ramfs_dir_inode_operations;
	75	inode->i_fop = &simple_dir_operations;
	76
	77	/* directory inodes start off with i_nlink == 2 (for "." entry) */
	78	inode->i_nlink++;
	79	break;
	80	case S_IFLNK:
	81	inode->i_op = &page_symlink_inode_operations;
	82	break;
	83	}
	84	}
	85	return inode;
	86	}
	87
	88	/*
	89	* File creation. Allocate an inode, and we're done..
	90	*/
	91	/* SMP-safe */
	92	static int
	93	ramfs_mknod(struct inode dir, struct dentry dentry, int mode, dev_t dev)
	94	{
	95	struct inode * inode = ramfs_get_inode(dir->i_sb, mode, dev);
	96	int error = -ENOSPC;
	97
	98	if (inode) {
	99	if (dir->i_mode & S_ISGID) {
	100	inode->i_gid = dir->i_gid;
	101	if (S_ISDIR(mode))
	102	inode->i_mode \|= S_ISGID;
	103	}
	104	d_instantiate(dentry, inode);
	105	dget(dentry); /* Extra count - pin the dentry in core */
	106	error = 0;
107	}
108	return error;
109	}
110
111	static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
112	{
113	int retval = ramfs_mknod(dir, dentry, mode \| S_IFDIR, 0);
114	if (!retval)
115	dir->i_nlink++;
116	return retval;
117	}
118
119	static int ramfs_create(struct inode dir, struct dentry dentry, int mode, struct nameidata *nd)
120	{
121	return ramfs_mknod(dir, dentry, mode \| S_IFREG, 0);
122	}
123
124	static int ramfs_symlink(struct inode * dir, struct dentry dentry, const char symname)
125	{
126	struct inode *inode;
127	int error = -ENOSPC;
128
129	inode = ramfs_get_inode(dir->i_sb, S_IFLNK\|S_IRWXUGO, 0);
130	if (inode) {
131	int l = strlen(symname)+1;
132	error = page_symlink(inode, symname, l);
133	if (!error) {
134	if (dir->i_mode & S_ISGID)
135	inode->i_gid = dir->i_gid;
136	d_instantiate(dentry, inode);
137	dget(dentry);
138	} else
139	iput(inode);
140	}
141	return error;
142	}
143
1da177e4 LT	144	static struct inode_operations ramfs_dir_inode_operations = {
	145	.create = ramfs_create,
	146	.lookup = simple_lookup,
	147	.link = simple_link,
	148	.unlink = simple_unlink,
	149	.symlink = ramfs_symlink,
	150	.mkdir = ramfs_mkdir,
	151	.rmdir = simple_rmdir,
	152	.mknod = ramfs_mknod,
	153	.rename = simple_rename,
	154	};
	155
	156	static struct super_operations ramfs_ops = {
	157	.statfs = simple_statfs,
	158	.drop_inode = generic_delete_inode,
	159	};
	160
	161	static int ramfs_fill_super(struct super_block * sb, void * data, int silent)
	162	{
	163	struct inode * inode;
	164	struct dentry * root;
	165
	166	sb->s_maxbytes = MAX_LFS_FILESIZE;
	167	sb->s_blocksize = PAGE_CACHE_SIZE;
	168	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	169	sb->s_magic = RAMFS_MAGIC;
	170	sb->s_op = &ramfs_ops;
	171	sb->s_time_gran = 1;
	172	inode = ramfs_get_inode(sb, S_IFDIR \| 0755, 0);
	173	if (!inode)
	174	return -ENOMEM;
	175
	176	root = d_alloc_root(inode);
	177	if (!root) {
	178	iput(inode);
	179	return -ENOMEM;
	180	}
	181	sb->s_root = root;
	182	return 0;
	183	}
	184
	185	struct super_block ramfs_get_sb(struct file_system_type fs_type,
	186	int flags, const char dev_name, void data)
	187	{
	188	return get_sb_nodev(fs_type, flags, data, ramfs_fill_super);
	189	}
	190
	191	static struct super_block rootfs_get_sb(struct file_system_type fs_type,
	192	int flags, const char dev_name, void data)
	193	{
	194	return get_sb_nodev(fs_type, flags\|MS_NOUSER, data, ramfs_fill_super);
	195	}
	196
	197	static struct file_system_type ramfs_fs_type = {
	198	.name = "ramfs",
	199	.get_sb = ramfs_get_sb,
	200	.kill_sb = kill_litter_super,
	201	};
	202	static struct file_system_type rootfs_fs_type = {
	203	.name = "rootfs",
	204	.get_sb = rootfs_get_sb,
	205	.kill_sb = kill_litter_super,
	206	};
	207
208	static int __init init_ramfs_fs(void)
209	{
210	return register_filesystem(&ramfs_fs_type);
211	}
212
213	static void __exit exit_ramfs_fs(void)
214	{
215	unregister_filesystem(&ramfs_fs_type);
216	}
217
218	module_init(init_ramfs_fs)
219	module_exit(exit_ramfs_fs)
220
221	int __init init_rootfs(void)
222	{
223	return register_filesystem(&rootfs_fs_type);
224	}
225
226	MODULE_LICENSE("GPL");