[deliverable/linux.git] / mm / tiny-shmem.c

/*
 * tiny-shmem.c: simple shmemfs and tmpfs using ramfs code
 *
 * Matt Mackall <mpm@selenic.com> January, 2004
 * derived from mm/shmem.c and fs/ramfs/inode.c
 *
 * This is intended for small system where the benefits of the full
 * shmem code (swap-backed and resource-limited) are outweighed by
 * their complexity. On systems without swap this code should be
 * effectively equivalent, but much lighter weight.
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/vfs.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/swap.h>
#include <linux/ramfs.h>

static struct file_system_type tmpfs_fs_type = {
	.name		= "tmpfs",
	.get_sb		= ramfs_get_sb,
	.kill_sb	= kill_litter_super,
};

static struct vfsmount *shm_mnt;

static int __init init_tmpfs(void)
{
	BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);

	shm_mnt = kern_mount(&tmpfs_fs_type);
	BUG_ON(IS_ERR(shm_mnt));

	return 0;
}
module_init(init_tmpfs)

/**
 * shmem_file_setup - get an unlinked file living in tmpfs
 * @name: name for dentry (to be seen in /proc/<pid>/maps
 * @size: size to be set for the file
 * @flags: vm_flags
 */
struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
{
	int error;
	struct file *file;
	struct inode *inode;
	struct dentry *dentry, *root;
	struct qstr this;

	if (IS_ERR(shm_mnt))
		return (void *)shm_mnt;

	error = -ENOMEM;
	this.name = name;
	this.len = strlen(name);
	this.hash = 0; /* will go */
	root = shm_mnt->mnt_root;
	dentry = d_alloc(root, &this);
	if (!dentry)
		goto put_memory;

	error = -ENFILE;
	file = get_empty_filp();
	if (!file)
		goto put_dentry;

	error = -ENOSPC;
	inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
	if (!inode)
		goto close_file;

	d_instantiate(dentry, inode);
	inode->i_size = size;
	inode->i_nlink = 0;	/* It is unlinked */
	init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
			&ramfs_file_operations);
	return file;

close_file:
	put_filp(file);
put_dentry:
	dput(dentry);
put_memory:
	return ERR_PTR(error);
}

/**
 * shmem_zero_setup - setup a shared anonymous mapping
 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
 */
int shmem_zero_setup(struct vm_area_struct *vma)
{
	struct file *file;
	loff_t size = vma->vm_end - vma->vm_start;

	file = shmem_file_setup("dev/zero", size, vma->vm_flags);
	if (IS_ERR(file))
		return PTR_ERR(file);

	if (vma->vm_file)
		fput(vma->vm_file);
	vma->vm_file = file;
	vma->vm_ops = &generic_file_vm_ops;
	return 0;
}

int shmem_unuse(swp_entry_t entry, struct page *page)
{
	return 0;
}

#ifndef CONFIG_MMU
unsigned long shmem_get_unmapped_area(struct file *file,
				      unsigned long addr,
				      unsigned long len,
				      unsigned long pgoff,
				      unsigned long flags)
{
	return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags);
}
#endif
Commit	Line	Data
1da177e4 LT	1	/*
	2	* tiny-shmem.c: simple shmemfs and tmpfs using ramfs code
	3	*
	4	* Matt Mackall <mpm@selenic.com> January, 2004
	5	* derived from mm/shmem.c and fs/ramfs/inode.c
	6	*
	7	* This is intended for small system where the benefits of the full
	8	* shmem code (swap-backed and resource-limited) are outweighed by
	9	* their complexity. On systems without swap this code should be
	10	* effectively equivalent, but much lighter weight.
	11	*/
	12
	13	#include <linux/fs.h>
	14	#include <linux/init.h>
1da177e4 LT	15	#include <linux/vfs.h>
	16	#include <linux/mount.h>
	17	#include <linux/file.h>
	18	#include <linux/mm.h>
	19	#include <linux/module.h>
	20	#include <linux/swap.h>
	21	#include <linux/ramfs.h>
	22
	23	static struct file_system_type tmpfs_fs_type = {
	24	.name = "tmpfs",
	25	.get_sb = ramfs_get_sb,
	26	.kill_sb = kill_litter_super,
	27	};
	28
	29	static struct vfsmount *shm_mnt;
	30
	31	static int __init init_tmpfs(void)
	32	{
5d57bd39 MM	33	BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
5d57bd39 MM	34
1da177e4	35	shm_mnt = kern_mount(&tmpfs_fs_type);
5d57bd39 MM	36	BUG_ON(IS_ERR(shm_mnt));
5d57bd39 MM	37
1da177e4 LT	38	return 0;
	39	}
	40	module_init(init_tmpfs)
	41
46711810	42	/**
1da177e4	43	* shmem_file_setup - get an unlinked file living in tmpfs
1da177e4 LT	44	* @name: name for dentry (to be seen in /proc/<pid>/maps
1da177e4 LT	45	* @size: size to be set for the file
46711810	46	* @flags: vm_flags
1da177e4 LT	47	*/
	48	struct file shmem_file_setup(char name, loff_t size, unsigned long flags)
	49	{
	50	int error;
	51	struct file *file;
	52	struct inode *inode;
	53	struct dentry dentry, root;
	54	struct qstr this;
	55
	56	if (IS_ERR(shm_mnt))
	57	return (void *)shm_mnt;
	58
	59	error = -ENOMEM;
	60	this.name = name;
	61	this.len = strlen(name);
	62	this.hash = 0; /* will go */
	63	root = shm_mnt->mnt_root;
	64	dentry = d_alloc(root, &this);
	65	if (!dentry)
	66	goto put_memory;
	67
ce8d2cdf	68	error = -ENFILE;
db203d53	69	file = get_empty_filp();
ce8d2cdf DH	70	if (!file)
ce8d2cdf DH	71	goto put_dentry;
b0e15190	72
db203d53 NP	73	error = -ENOSPC;
	74	inode = ramfs_get_inode(root->d_sb, S_IFREG \| S_IRWXUGO, 0);
	75	if (!inode)
b0e15190 DH	76	goto close_file;
b0e15190 DH	77
db203d53 NP	78	d_instantiate(dentry, inode);
	79	inode->i_size = size;
	80	inode->i_nlink = 0; /* It is unlinked */
	81	init_file(file, shm_mnt, dentry, FMODE_WRITE \| FMODE_READ,
	82	&ramfs_file_operations);
1da177e4 LT	83	return file;
	84
	85	close_file:
	86	put_filp(file);
	87	put_dentry:
	88	dput(dentry);
	89	put_memory:
	90	return ERR_PTR(error);
	91	}
	92
46711810	93	/**
1da177e4	94	* shmem_zero_setup - setup a shared anonymous mapping
1da177e4 LT	95	* @vma: the vma to be mmapped is prepared by do_mmap_pgoff
	96	*/
	97	int shmem_zero_setup(struct vm_area_struct *vma)
	98	{
	99	struct file *file;
	100	loff_t size = vma->vm_end - vma->vm_start;
	101
	102	file = shmem_file_setup("dev/zero", size, vma->vm_flags);
	103	if (IS_ERR(file))
	104	return PTR_ERR(file);
	105
	106	if (vma->vm_file)
	107	fput(vma->vm_file);
	108	vma->vm_file = file;
	109	vma->vm_ops = &generic_file_vm_ops;
	110	return 0;
	111	}
	112
	113	int shmem_unuse(swp_entry_t entry, struct page *page)
	114	{
	115	return 0;
	116	}
b0e15190	117
b0e15190 DH	118	#ifndef CONFIG_MMU
	119	unsigned long shmem_get_unmapped_area(struct file *file,
	120	unsigned long addr,
	121	unsigned long len,
	122	unsigned long pgoff,
	123	unsigned long flags)
	124	{
	125	return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags);
	126	}
	127	#endif