[linux-block.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
 *
 */
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 = -ENOSPC;
	inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
	if (!inode)
		goto put_dentry;

	d_instantiate(dentry, inode);
	error = -ENFILE;
	file = alloc_file(shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
			&ramfs_file_operations);
	if (!file)
		goto put_dentry;

	inode->i_nlink = 0;	/* It is unlinked */

	/* notify everyone as to the change of file size */
	error = do_truncate(dentry, size, 0, file);
	if (error < 0)
		goto close_file;

	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;
}

#if 0
int shmem_mmap(struct file *file, struct vm_area_struct *vma)
{
	file_accessed(file);
#ifndef CONFIG_MMU
	return ramfs_nommu_mmap(file, vma);
#else
	return 0;
#endif
}
#endif  /*  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
	42	/*
	43	* shmem_file_setup - get an unlinked file living in tmpfs
	44	*
	45	* @name: name for dentry (to be seen in /proc/<pid>/maps
	46	* @size: size to be set for the file
	47	*
	48	*/
	49	struct file shmem_file_setup(char name, loff_t size, unsigned long flags)
	50	{
	51	int error;
	52	struct file *file;
	53	struct inode *inode;
	54	struct dentry dentry, root;
	55	struct qstr this;
	56
	57	if (IS_ERR(shm_mnt))
	58	return (void *)shm_mnt;
	59
	60	error = -ENOMEM;
	61	this.name = name;
	62	this.len = strlen(name);
	63	this.hash = 0; /* will go */
	64	root = shm_mnt->mnt_root;
	65	dentry = d_alloc(root, &this);
	66	if (!dentry)
	67	goto put_memory;
	68
1da177e4 LT	69	error = -ENOSPC;
	70	inode = ramfs_get_inode(root->d_sb, S_IFREG \| S_IRWXUGO, 0);
	71	if (!inode)
ce8d2cdf	72	goto put_dentry;
1da177e4 LT	73
1da177e4 LT	74	d_instantiate(dentry, inode);
ce8d2cdf DH	75	error = -ENFILE;
	76	file = alloc_file(shm_mnt, dentry, FMODE_WRITE \| FMODE_READ,
	77	&ramfs_file_operations);
	78	if (!file)
	79	goto put_dentry;
b0e15190	80
ce8d2cdf	81	inode->i_nlink = 0; /* It is unlinked */
b0e15190 DH	82
b0e15190 DH	83	/* notify everyone as to the change of file size */
2a7e2f7d	84	error = do_truncate(dentry, size, 0, file);
b0e15190 DH	85	if (error < 0)
	86	goto close_file;
	87
1da177e4 LT	88	return file;
	89
	90	close_file:
	91	put_filp(file);
	92	put_dentry:
	93	dput(dentry);
	94	put_memory:
	95	return ERR_PTR(error);
	96	}
	97
	98	/*
	99	* shmem_zero_setup - setup a shared anonymous mapping
	100	*
	101	* @vma: the vma to be mmapped is prepared by do_mmap_pgoff
	102	*/
	103	int shmem_zero_setup(struct vm_area_struct *vma)
	104	{
	105	struct file *file;
	106	loff_t size = vma->vm_end - vma->vm_start;
	107
	108	file = shmem_file_setup("dev/zero", size, vma->vm_flags);
	109	if (IS_ERR(file))
	110	return PTR_ERR(file);
	111
	112	if (vma->vm_file)
	113	fput(vma->vm_file);
	114	vma->vm_file = file;
	115	vma->vm_ops = &generic_file_vm_ops;
	116	return 0;
	117	}
	118
	119	int shmem_unuse(swp_entry_t entry, struct page *page)
	120	{
	121	return 0;
	122	}
b0e15190	123
9b83a6a8	124	#if 0
b0e15190 DH	125	int shmem_mmap(struct file file, struct vm_area_struct vma)
	126	{
	127	file_accessed(file);
	128	#ifndef CONFIG_MMU
	129	return ramfs_nommu_mmap(file, vma);
	130	#else
	131	return 0;
	132	#endif
	133	}
9b83a6a8	134	#endif /* 0 */
b0e15190 DH	135
	136	#ifndef CONFIG_MMU
	137	unsigned long shmem_get_unmapped_area(struct file *file,
	138	unsigned long addr,
	139	unsigned long len,
	140	unsigned long pgoff,
	141	unsigned long flags)
	142	{
	143	return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags);
	144	}
	145	#endif