[linux.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/time.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/ramfs.h>
#include <linux/sched.h>
#include <linux/parser.h>
#include <asm/uaccess.h>
#include "internal.h"

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

#define RAMFS_DEFAULT_MODE	0755

static const struct super_operations ramfs_ops;
static const struct inode_operations ramfs_dir_inode_operations;

static struct backing_dev_info ramfs_backing_dev_info = {
	.name		= "ramfs",
	.ra_pages	= 0,	/* No readahead */
	.capabilities	= BDI_CAP_NO_ACCT_AND_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_mapping->a_ops = &ramfs_aops;
		inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
		mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
		mapping_set_unevictable(inode->i_mapping);
		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) */
			inc_nlink(inode);
			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;
		dir->i_mtime = dir->i_ctime = CURRENT_TIME;
	}
	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)
		inc_nlink(dir);
	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);
			dir->i_mtime = dir->i_ctime = CURRENT_TIME;
		} else
			iput(inode);
	}
	return error;
}

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

struct ramfs_mount_opts {
	umode_t mode;
};

enum {
	Opt_mode,
	Opt_err
};

static const match_table_t tokens = {
	{Opt_mode, "mode=%o"},
	{Opt_err, NULL}
};

struct ramfs_fs_info {
	struct ramfs_mount_opts mount_opts;
};

static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts)
{
	substring_t args[MAX_OPT_ARGS];
	int option;
	int token;
	char *p;

	opts->mode = RAMFS_DEFAULT_MODE;

	while ((p = strsep(&data, ",")) != NULL) {
		if (!*p)
			continue;

		token = match_token(p, tokens, args);
		switch (token) {
		case Opt_mode:
			if (match_octal(&args[0], &option))
				return -EINVAL;
			opts->mode = option & S_IALLUGO;
			break;
		/*
		 * We might like to report bad mount options here;
		 * but traditionally ramfs has ignored all mount options,
		 * and as it is used as a !CONFIG_SHMEM simple substitute
		 * for tmpfs, better continue to ignore other mount options.
		 */
		}
	}

	return 0;
}

static int ramfs_fill_super(struct super_block * sb, void * data, int silent)
{
	struct ramfs_fs_info *fsi;
	struct inode *inode = NULL;
	struct dentry *root;
	int err;

	save_mount_options(sb, data);

	fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
	sb->s_fs_info = fsi;
	if (!fsi) {
		err = -ENOMEM;
		goto fail;
	}

	err = ramfs_parse_options(data, &fsi->mount_opts);
	if (err)
		goto fail;

	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 | fsi->mount_opts.mode, 0);
	if (!inode) {
		err = -ENOMEM;
		goto fail;
	}

	root = d_alloc_root(inode);
	sb->s_root = root;
	if (!root) {
		err = -ENOMEM;
		goto fail;
	}

	return 0;
fail:
	kfree(fsi);
	sb->s_fs_info = NULL;
	iput(inode);
	return err;
}

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

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

static void ramfs_kill_sb(struct super_block *sb)
{
	kfree(sb->s_fs_info);
	kill_litter_super(sb);
}

static struct file_system_type ramfs_fs_type = {
	.name		= "ramfs",
	.get_sb		= ramfs_get_sb,
	.kill_sb	= ramfs_kill_sb,
};
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)
{
	int err;

	err = bdi_init(&ramfs_backing_dev_info);
	if (err)
		return err;

	err = register_filesystem(&rootfs_fs_type);
	if (err)
		bdi_destroy(&ramfs_backing_dev_info);

	return err;
}

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>
8dde0509	30	#include <linux/time.h>
1da177e4 LT	31	#include <linux/init.h>
1da177e4 LT	32	#include <linux/string.h>
1da177e4 LT	33	#include <linux/backing-dev.h>
1da177e4 LT	34	#include <linux/ramfs.h>
e8edc6e0	35	#include <linux/sched.h>
c3b1b1cb	36	#include <linux/parser.h>
1da177e4	37	#include <asm/uaccess.h>
642fb4d1	38	#include "internal.h"
1da177e4 LT	39
	40	/* some random number */
	41	#define RAMFS_MAGIC 0x858458f6
	42
c3b1b1cb WF	43	#define RAMFS_DEFAULT_MODE 0755
c3b1b1cb WF	44
ee9b6d61	45	static const struct super_operations ramfs_ops;
c5ef1c42	46	static const struct inode_operations ramfs_dir_inode_operations;
1da177e4 LT	47
1da177e4 LT	48	static struct backing_dev_info ramfs_backing_dev_info = {
d993831f	49	.name = "ramfs",
1da177e4	50	.ra_pages = 0, /* No readahead */
e4ad08fe	51	.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK \|
1da177e4 LT	52	BDI_CAP_MAP_DIRECT \| BDI_CAP_MAP_COPY \|
	53	BDI_CAP_READ_MAP \| BDI_CAP_WRITE_MAP \| BDI_CAP_EXEC_MAP,
	54	};
	55
	56	struct inode ramfs_get_inode(struct super_block sb, int mode, dev_t dev)
	57	{
	58	struct inode * inode = new_inode(sb);
	59
	60	if (inode) {
	61	inode->i_mode = mode;
0785f4da DH	62	inode->i_uid = current_fsuid();
0785f4da DH	63	inode->i_gid = current_fsgid();
1da177e4 LT	64	inode->i_mapping->a_ops = &ramfs_aops;
1da177e4 LT	65	inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
769848c0	66	mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
ba9ddf49	67	mapping_set_unevictable(inode->i_mapping);
1da177e4 LT	68	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	69	switch (mode & S_IFMT) {
	70	default:
	71	init_special_inode(inode, mode, dev);
	72	break;
	73	case S_IFREG:
	74	inode->i_op = &ramfs_file_inode_operations;
	75	inode->i_fop = &ramfs_file_operations;
	76	break;
	77	case S_IFDIR:
	78	inode->i_op = &ramfs_dir_inode_operations;
	79	inode->i_fop = &simple_dir_operations;
	80
	81	/* directory inodes start off with i_nlink == 2 (for "." entry) */
d8c76e6f	82	inc_nlink(inode);
1da177e4 LT	83	break;
	84	case S_IFLNK:
	85	inode->i_op = &page_symlink_inode_operations;
	86	break;
	87	}
	88	}
	89	return inode;
	90	}
	91
	92	/*
	93	* File creation. Allocate an inode, and we're done..
	94	*/
	95	/* SMP-safe */
	96	static int
	97	ramfs_mknod(struct inode dir, struct dentry dentry, int mode, dev_t dev)
	98	{
	99	struct inode * inode = ramfs_get_inode(dir->i_sb, mode, dev);
	100	int error = -ENOSPC;
	101
	102	if (inode) {
	103	if (dir->i_mode & S_ISGID) {
	104	inode->i_gid = dir->i_gid;
	105	if (S_ISDIR(mode))
	106	inode->i_mode \|= S_ISGID;
	107	}
	108	d_instantiate(dentry, inode);
	109	dget(dentry); /* Extra count - pin the dentry in core */
	110	error = 0;
8dde0509	111	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
1da177e4 LT	112	}
	113	return error;
	114	}
	115
	116	static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
	117	{
	118	int retval = ramfs_mknod(dir, dentry, mode \| S_IFDIR, 0);
	119	if (!retval)
d8c76e6f	120	inc_nlink(dir);
1da177e4 LT	121	return retval;
	122	}
	123
	124	static int ramfs_create(struct inode dir, struct dentry dentry, int mode, struct nameidata *nd)
	125	{
	126	return ramfs_mknod(dir, dentry, mode \| S_IFREG, 0);
	127	}
	128
	129	static int ramfs_symlink(struct inode * dir, struct dentry dentry, const char symname)
	130	{
	131	struct inode *inode;
	132	int error = -ENOSPC;
	133
	134	inode = ramfs_get_inode(dir->i_sb, S_IFLNK\|S_IRWXUGO, 0);
	135	if (inode) {
	136	int l = strlen(symname)+1;
	137	error = page_symlink(inode, symname, l);
	138	if (!error) {
	139	if (dir->i_mode & S_ISGID)
	140	inode->i_gid = dir->i_gid;
	141	d_instantiate(dentry, inode);
	142	dget(dentry);
ecbd3a63	143	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
1da177e4 LT	144	} else
	145	iput(inode);
	146	}
	147	return error;
	148	}
	149
c5ef1c42	150	static const struct inode_operations ramfs_dir_inode_operations = {
1da177e4 LT	151	.create = ramfs_create,
	152	.lookup = simple_lookup,
	153	.link = simple_link,
	154	.unlink = simple_unlink,
	155	.symlink = ramfs_symlink,
	156	.mkdir = ramfs_mkdir,
	157	.rmdir = simple_rmdir,
	158	.mknod = ramfs_mknod,
	159	.rename = simple_rename,
	160	};
	161
ee9b6d61	162	static const struct super_operations ramfs_ops = {
1da177e4 LT	163	.statfs = simple_statfs,
1da177e4 LT	164	.drop_inode = generic_delete_inode,
c3b1b1cb WF	165	.show_options = generic_show_options,
	166	};
	167
	168	struct ramfs_mount_opts {
	169	umode_t mode;
	170	};
	171
	172	enum {
	173	Opt_mode,
	174	Opt_err
	175	};
	176
	177	static const match_table_t tokens = {
	178	{Opt_mode, "mode=%o"},
	179	{Opt_err, NULL}
	180	};
	181
	182	struct ramfs_fs_info {
	183	struct ramfs_mount_opts mount_opts;
1da177e4 LT	184	};
1da177e4 LT	185
c3b1b1cb WF	186	static int ramfs_parse_options(char data, struct ramfs_mount_opts opts)
	187	{
	188	substring_t args[MAX_OPT_ARGS];
	189	int option;
	190	int token;
	191	char *p;
	192
	193	opts->mode = RAMFS_DEFAULT_MODE;
	194
	195	while ((p = strsep(&data, ",")) != NULL) {
	196	if (!*p)
	197	continue;
	198
	199	token = match_token(p, tokens, args);
	200	switch (token) {
	201	case Opt_mode:
	202	if (match_octal(&args[0], &option))
	203	return -EINVAL;
	204	opts->mode = option & S_IALLUGO;
	205	break;
0a8eba9b MF	206	/*
	207	* We might like to report bad mount options here;
	208	* but traditionally ramfs has ignored all mount options,
	209	* and as it is used as a !CONFIG_SHMEM simple substitute
	210	* for tmpfs, better continue to ignore other mount options.
	211	*/
c3b1b1cb WF	212	}
	213	}
	214
	215	return 0;
	216	}
	217
1da177e4 LT	218	static int ramfs_fill_super(struct super_block * sb, void * data, int silent)
1da177e4 LT	219	{
c3b1b1cb WF	220	struct ramfs_fs_info *fsi;
	221	struct inode *inode = NULL;
	222	struct dentry *root;
	223	int err;
	224
	225	save_mount_options(sb, data);
	226
	227	fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
f8201abc	228	sb->s_fs_info = fsi;
c3b1b1cb WF	229	if (!fsi) {
	230	err = -ENOMEM;
	231	goto fail;
	232	}
c3b1b1cb WF	233
	234	err = ramfs_parse_options(data, &fsi->mount_opts);
	235	if (err)
	236	goto fail;
1da177e4	237
f8201abc IM	238	sb->s_maxbytes = MAX_LFS_FILESIZE;
	239	sb->s_blocksize = PAGE_CACHE_SIZE;
	240	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	241	sb->s_magic = RAMFS_MAGIC;
	242	sb->s_op = &ramfs_ops;
	243	sb->s_time_gran = 1;
	244
c3b1b1cb WF	245	inode = ramfs_get_inode(sb, S_IFDIR \| fsi->mount_opts.mode, 0);
	246	if (!inode) {
	247	err = -ENOMEM;
	248	goto fail;
	249	}
1da177e4 LT	250
1da177e4 LT	251	root = d_alloc_root(inode);
f8201abc	252	sb->s_root = root;
1da177e4	253	if (!root) {
c3b1b1cb WF	254	err = -ENOMEM;
c3b1b1cb WF	255	goto fail;
1da177e4	256	}
f8201abc	257
1da177e4	258	return 0;
c3b1b1cb WF	259	fail:
c3b1b1cb WF	260	kfree(fsi);
f8201abc	261	sb->s_fs_info = NULL;
c3b1b1cb WF	262	iput(inode);
c3b1b1cb WF	263	return err;
1da177e4 LT	264	}
1da177e4 LT	265
454e2398 DH	266	int ramfs_get_sb(struct file_system_type *fs_type,
454e2398 DH	267	int flags, const char dev_name, void data, struct vfsmount *mnt)
1da177e4	268	{
454e2398	269	return get_sb_nodev(fs_type, flags, data, ramfs_fill_super, mnt);
1da177e4 LT	270	}
1da177e4 LT	271
454e2398 DH	272	static int rootfs_get_sb(struct file_system_type *fs_type,
454e2398 DH	273	int flags, const char dev_name, void data, struct vfsmount *mnt)
1da177e4	274	{
454e2398 DH	275	return get_sb_nodev(fs_type, flags\|MS_NOUSER, data, ramfs_fill_super,
454e2398 DH	276	mnt);
1da177e4 LT	277	}
1da177e4 LT	278
c3b1b1cb WF	279	static void ramfs_kill_sb(struct super_block *sb)
	280	{
	281	kfree(sb->s_fs_info);
	282	kill_litter_super(sb);
	283	}
	284
1da177e4 LT	285	static struct file_system_type ramfs_fs_type = {
	286	.name = "ramfs",
	287	.get_sb = ramfs_get_sb,
c3b1b1cb	288	.kill_sb = ramfs_kill_sb,
1da177e4 LT	289	};
	290	static struct file_system_type rootfs_fs_type = {
	291	.name = "rootfs",
	292	.get_sb = rootfs_get_sb,
	293	.kill_sb = kill_litter_super,
	294	};
	295
	296	static int __init init_ramfs_fs(void)
	297	{
	298	return register_filesystem(&ramfs_fs_type);
	299	}
	300
	301	static void __exit exit_ramfs_fs(void)
	302	{
	303	unregister_filesystem(&ramfs_fs_type);
	304	}
	305
	306	module_init(init_ramfs_fs)
	307	module_exit(exit_ramfs_fs)
	308
	309	int __init init_rootfs(void)
	310	{
e0bf68dd PZ	311	int err;
	312
	313	err = bdi_init(&ramfs_backing_dev_info);
	314	if (err)
	315	return err;
	316
	317	err = register_filesystem(&rootfs_fs_type);
	318	if (err)
	319	bdi_destroy(&ramfs_backing_dev_info);
	320
	321	return err;
1da177e4 LT	322	}
	323
	324	MODULE_LICENSE("GPL");