[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/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 <linux/magic.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include "internal.h"

#define RAMFS_DEFAULT_MODE	0755

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

static const struct address_space_operations ramfs_aops = {
	.readpage	= simple_readpage,
	.write_begin	= simple_write_begin,
	.write_end	= simple_write_end,
	.set_page_dirty	= __set_page_dirty_no_writeback,
};

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

	if (inode) {
		inode->i_ino = get_next_ino();
		inode_init_owner(inode, dir, mode);
		inode->i_mapping->a_ops = &ramfs_aops;
		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(inode);
		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;
			inode_nohighmem(inode);
			break;
		}
	}
	return inode;
}

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

	if (inode) {
		d_instantiate(dentry, inode);
		dget(dentry);	/* Extra count - pin the dentry in core */
		error = 0;
		dir->i_mtime = dir->i_ctime = current_time(dir);
	}
	return error;
}

static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, umode_t 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, umode_t mode, bool excl)
{
	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, dir, S_IFLNK|S_IRWXUGO, 0);
	if (inode) {
		int l = strlen(symname)+1;
		error = page_symlink(inode, symname, l);
		if (!error) {
			d_instantiate(dentry, inode);
			dget(dentry);
			dir->i_mtime = dir->i_ctime = current_time(dir);
		} 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;
}

int ramfs_fill_super(struct super_block *sb, void *data, int silent)
{
	struct ramfs_fs_info *fsi;
	struct inode *inode;
	int err;

	save_mount_options(sb, data);

	fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
	sb->s_fs_info = fsi;
	if (!fsi)
		return -ENOMEM;

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

	sb->s_maxbytes		= MAX_LFS_FILESIZE;
	sb->s_blocksize		= PAGE_SIZE;
	sb->s_blocksize_bits	= PAGE_SHIFT;
	sb->s_magic		= RAMFS_MAGIC;
	sb->s_op		= &ramfs_ops;
	sb->s_time_gran		= 1;

	inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
	sb->s_root = d_make_root(inode);
	if (!sb->s_root)
		return -ENOMEM;

	return 0;
}

struct dentry *ramfs_mount(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return mount_nodev(fs_type, flags, data, ramfs_fill_super);
}

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",
	.mount		= ramfs_mount,
	.kill_sb	= ramfs_kill_sb,
	.fs_flags	= FS_USERNS_MOUNT,
};

int __init init_ramfs_fs(void)
{
	static unsigned long once;

	if (test_and_set_bit(0, &once))
		return 0;
	return register_filesystem(&ramfs_fs_type);
}
fs_initcall(init_ramfs_fs);
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
1da177e4 LT	26	#include <linux/fs.h>
	27	#include <linux/pagemap.h>
	28	#include <linux/highmem.h>
8dde0509	29	#include <linux/time.h>
1da177e4 LT	30	#include <linux/init.h>
1da177e4 LT	31	#include <linux/string.h>
1da177e4 LT	32	#include <linux/backing-dev.h>
1da177e4 LT	33	#include <linux/ramfs.h>
e8edc6e0	34	#include <linux/sched.h>
c3b1b1cb	35	#include <linux/parser.h>
a7e3108c	36	#include <linux/magic.h>
5a0e3ad6	37	#include <linux/slab.h>
7c0f6ba6	38	#include <linux/uaccess.h>
642fb4d1	39	#include "internal.h"
1da177e4	40
c3b1b1cb WF	41	#define RAMFS_DEFAULT_MODE 0755
c3b1b1cb WF	42
ee9b6d61	43	static const struct super_operations ramfs_ops;
c5ef1c42	44	static const struct inode_operations ramfs_dir_inode_operations;
1da177e4	45
87e06aa3 AL	46	static const struct address_space_operations ramfs_aops = {
	47	.readpage = simple_readpage,
	48	.write_begin = simple_write_begin,
	49	.write_end = simple_write_end,
	50	.set_page_dirty = __set_page_dirty_no_writeback,
	51	};
	52
454abafe	53	struct inode ramfs_get_inode(struct super_block sb,
632861f0	54	const struct inode *dir, umode_t mode, dev_t dev)
1da177e4 LT	55	{
	56	struct inode * inode = new_inode(sb);
	57
	58	if (inode) {
85fe4025	59	inode->i_ino = get_next_ino();
454abafe	60	inode_init_owner(inode, dir, mode);
1da177e4	61	inode->i_mapping->a_ops = &ramfs_aops;
769848c0	62	mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
ba9ddf49	63	mapping_set_unevictable(inode->i_mapping);
078cd827	64	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
1da177e4 LT	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) */
d8c76e6f	78	inc_nlink(inode);
1da177e4 LT	79	break;
	80	case S_IFLNK:
	81	inode->i_op = &page_symlink_inode_operations;
21fc61c7	82	inode_nohighmem(inode);
1da177e4 LT	83	break;
	84	}
	85	}
	86	return inode;
	87	}
	88
	89	/*
	90	* File creation. Allocate an inode, and we're done..
	91	*/
	92	/* SMP-safe */
	93	static int
1a67aafb	94	ramfs_mknod(struct inode dir, struct dentry dentry, umode_t mode, dev_t dev)
1da177e4	95	{
454abafe	96	struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev);
1da177e4 LT	97	int error = -ENOSPC;
	98
	99	if (inode) {
1da177e4 LT	100	d_instantiate(dentry, inode);
	101	dget(dentry); /* Extra count - pin the dentry in core */
	102	error = 0;
078cd827	103	dir->i_mtime = dir->i_ctime = current_time(dir);
1da177e4 LT	104	}
	105	return error;
	106	}
	107
18bb1db3	108	static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
1da177e4 LT	109	{
	110	int retval = ramfs_mknod(dir, dentry, mode \| S_IFDIR, 0);
	111	if (!retval)
d8c76e6f	112	inc_nlink(dir);
1da177e4 LT	113	return retval;
	114	}
	115
ebfc3b49	116	static int ramfs_create(struct inode dir, struct dentry dentry, umode_t mode, bool excl)
1da177e4 LT	117	{
	118	return ramfs_mknod(dir, dentry, mode \| S_IFREG, 0);
	119	}
	120
	121	static int ramfs_symlink(struct inode * dir, struct dentry dentry, const char symname)
	122	{
	123	struct inode *inode;
	124	int error = -ENOSPC;
	125
454abafe	126	inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK\|S_IRWXUGO, 0);
1da177e4 LT	127	if (inode) {
	128	int l = strlen(symname)+1;
	129	error = page_symlink(inode, symname, l);
	130	if (!error) {
1da177e4 LT	131	d_instantiate(dentry, inode);
1da177e4 LT	132	dget(dentry);
078cd827	133	dir->i_mtime = dir->i_ctime = current_time(dir);
1da177e4 LT	134	} else
	135	iput(inode);
	136	}
	137	return error;
	138	}
	139
c5ef1c42	140	static const struct inode_operations ramfs_dir_inode_operations = {
1da177e4 LT	141	.create = ramfs_create,
	142	.lookup = simple_lookup,
	143	.link = simple_link,
	144	.unlink = simple_unlink,
	145	.symlink = ramfs_symlink,
	146	.mkdir = ramfs_mkdir,
	147	.rmdir = simple_rmdir,
	148	.mknod = ramfs_mknod,
	149	.rename = simple_rename,
	150	};
	151
ee9b6d61	152	static const struct super_operations ramfs_ops = {
1da177e4 LT	153	.statfs = simple_statfs,
1da177e4 LT	154	.drop_inode = generic_delete_inode,
c3b1b1cb WF	155	.show_options = generic_show_options,
	156	};
	157
	158	struct ramfs_mount_opts {
	159	umode_t mode;
	160	};
	161
	162	enum {
	163	Opt_mode,
	164	Opt_err
	165	};
	166
	167	static const match_table_t tokens = {
	168	{Opt_mode, "mode=%o"},
	169	{Opt_err, NULL}
	170	};
	171
	172	struct ramfs_fs_info {
	173	struct ramfs_mount_opts mount_opts;
1da177e4 LT	174	};
1da177e4 LT	175
c3b1b1cb WF	176	static int ramfs_parse_options(char data, struct ramfs_mount_opts opts)
	177	{
	178	substring_t args[MAX_OPT_ARGS];
	179	int option;
	180	int token;
	181	char *p;
	182
	183	opts->mode = RAMFS_DEFAULT_MODE;
	184
	185	while ((p = strsep(&data, ",")) != NULL) {
	186	if (!*p)
	187	continue;
	188
	189	token = match_token(p, tokens, args);
	190	switch (token) {
	191	case Opt_mode:
	192	if (match_octal(&args[0], &option))
	193	return -EINVAL;
	194	opts->mode = option & S_IALLUGO;
	195	break;
0a8eba9b MF	196	/*
	197	* We might like to report bad mount options here;
	198	* but traditionally ramfs has ignored all mount options,
	199	* and as it is used as a !CONFIG_SHMEM simple substitute
	200	* for tmpfs, better continue to ignore other mount options.
	201	*/
c3b1b1cb WF	202	}
	203	}
	204
	205	return 0;
	206	}
	207
da5e4ef7	208	int ramfs_fill_super(struct super_block sb, void data, int silent)
1da177e4	209	{
c3b1b1cb	210	struct ramfs_fs_info *fsi;
318ceed0	211	struct inode *inode;
c3b1b1cb WF	212	int err;
	213
	214	save_mount_options(sb, data);
	215
	216	fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
f8201abc	217	sb->s_fs_info = fsi;
318ceed0 AV	218	if (!fsi)
318ceed0 AV	219	return -ENOMEM;
c3b1b1cb WF	220
	221	err = ramfs_parse_options(data, &fsi->mount_opts);
	222	if (err)
318ceed0	223	return err;
1da177e4	224
f8201abc	225	sb->s_maxbytes = MAX_LFS_FILESIZE;
09cbfeaf KS	226	sb->s_blocksize = PAGE_SIZE;
09cbfeaf KS	227	sb->s_blocksize_bits = PAGE_SHIFT;
f8201abc IM	228	sb->s_magic = RAMFS_MAGIC;
	229	sb->s_op = &ramfs_ops;
	230	sb->s_time_gran = 1;
	231
454abafe	232	inode = ramfs_get_inode(sb, NULL, S_IFDIR \| fsi->mount_opts.mode, 0);
48fde701	233	sb->s_root = d_make_root(inode);
318ceed0 AV	234	if (!sb->s_root)
318ceed0 AV	235	return -ENOMEM;
f8201abc	236
1da177e4 LT	237	return 0;
	238	}
	239
3c26ff6e AV	240	struct dentry ramfs_mount(struct file_system_type fs_type,
3c26ff6e AV	241	int flags, const char dev_name, void data)
1da177e4	242	{
3c26ff6e	243	return mount_nodev(fs_type, flags, data, ramfs_fill_super);
1da177e4 LT	244	}
1da177e4 LT	245
c3b1b1cb WF	246	static void ramfs_kill_sb(struct super_block *sb)
	247	{
	248	kfree(sb->s_fs_info);
	249	kill_litter_super(sb);
	250	}
	251
1da177e4 LT	252	static struct file_system_type ramfs_fs_type = {
1da177e4 LT	253	.name = "ramfs",
3c26ff6e	254	.mount = ramfs_mount,
c3b1b1cb	255	.kill_sb = ramfs_kill_sb,
b3c6761d	256	.fs_flags = FS_USERNS_MOUNT,
1da177e4	257	};
1da177e4	258
57f150a5	259	int __init init_ramfs_fs(void)
1da177e4	260	{
4bbee76b	261	static unsigned long once;
4bbee76b RL	262
	263	if (test_and_set_bit(0, &once))
	264	return 0;
b4caecd4	265	return register_filesystem(&ramfs_fs_type);
1da177e4	266	}
af52b040	267	fs_initcall(init_ramfs_fs);