| /* |
| * 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/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_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; |
| 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) |
| 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); |
| dir->i_mtime = dir->i_ctime = CURRENT_TIME; |
| } 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; |
| } |
| |
| 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 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"); |