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0620d9193c
Since ramfs is hard-selected to "y", the module leftovers make no sense. Signed-off-by: Richard Weinberger <richard@nod.at> Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
306 lines
6.9 KiB
C
306 lines
6.9 KiB
C
/*
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* Resizable simple ram filesystem for Linux.
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*
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* Copyright (C) 2000 Linus Torvalds.
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* 2000 Transmeta Corp.
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*
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* Usage limits added by David Gibson, Linuxcare Australia.
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* This file is released under the GPL.
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*/
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/*
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* NOTE! This filesystem is probably most useful
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* not as a real filesystem, but as an example of
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* how virtual filesystems can be written.
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*
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* It doesn't get much simpler than this. Consider
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* that this file implements the full semantics of
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* a POSIX-compliant read-write filesystem.
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*
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* Note in particular how the filesystem does not
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* need to implement any data structures of its own
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* to keep track of the virtual data: using the VFS
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* caches is sufficient.
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*/
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/time.h>
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#include <linux/init.h>
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#include <linux/string.h>
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#include <linux/backing-dev.h>
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#include <linux/ramfs.h>
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#include <linux/sched.h>
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#include <linux/parser.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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#define RAMFS_DEFAULT_MODE 0755
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static const struct super_operations ramfs_ops;
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static const struct inode_operations ramfs_dir_inode_operations;
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static struct backing_dev_info ramfs_backing_dev_info = {
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.name = "ramfs",
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.ra_pages = 0, /* No readahead */
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.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK |
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BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
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BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
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};
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struct inode *ramfs_get_inode(struct super_block *sb,
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const struct inode *dir, int mode, dev_t dev)
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{
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struct inode * inode = new_inode(sb);
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if (inode) {
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inode->i_ino = get_next_ino();
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inode_init_owner(inode, dir, mode);
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inode->i_mapping->a_ops = &ramfs_aops;
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inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
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mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
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mapping_set_unevictable(inode->i_mapping);
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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switch (mode & S_IFMT) {
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default:
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init_special_inode(inode, mode, dev);
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break;
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case S_IFREG:
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inode->i_op = &ramfs_file_inode_operations;
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inode->i_fop = &ramfs_file_operations;
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break;
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case S_IFDIR:
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inode->i_op = &ramfs_dir_inode_operations;
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inode->i_fop = &simple_dir_operations;
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/* directory inodes start off with i_nlink == 2 (for "." entry) */
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inc_nlink(inode);
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break;
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case S_IFLNK:
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inode->i_op = &page_symlink_inode_operations;
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break;
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}
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}
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return inode;
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}
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/*
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* File creation. Allocate an inode, and we're done..
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*/
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/* SMP-safe */
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static int
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ramfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
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{
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struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev);
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int error = -ENOSPC;
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if (inode) {
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d_instantiate(dentry, inode);
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dget(dentry); /* Extra count - pin the dentry in core */
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error = 0;
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dir->i_mtime = dir->i_ctime = CURRENT_TIME;
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}
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return error;
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}
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static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
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{
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int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
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if (!retval)
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inc_nlink(dir);
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return retval;
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}
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static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
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{
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return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
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}
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static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
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{
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struct inode *inode;
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int error = -ENOSPC;
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inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
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if (inode) {
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int l = strlen(symname)+1;
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error = page_symlink(inode, symname, l);
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if (!error) {
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d_instantiate(dentry, inode);
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dget(dentry);
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dir->i_mtime = dir->i_ctime = CURRENT_TIME;
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} else
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iput(inode);
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}
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return error;
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}
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static const struct inode_operations ramfs_dir_inode_operations = {
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.create = ramfs_create,
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.lookup = simple_lookup,
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.link = simple_link,
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.unlink = simple_unlink,
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.symlink = ramfs_symlink,
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.mkdir = ramfs_mkdir,
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.rmdir = simple_rmdir,
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.mknod = ramfs_mknod,
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.rename = simple_rename,
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};
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static const struct super_operations ramfs_ops = {
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.statfs = simple_statfs,
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.drop_inode = generic_delete_inode,
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.show_options = generic_show_options,
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};
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struct ramfs_mount_opts {
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umode_t mode;
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};
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enum {
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Opt_mode,
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Opt_err
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};
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static const match_table_t tokens = {
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{Opt_mode, "mode=%o"},
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{Opt_err, NULL}
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};
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struct ramfs_fs_info {
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struct ramfs_mount_opts mount_opts;
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};
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static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts)
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{
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substring_t args[MAX_OPT_ARGS];
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int option;
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int token;
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char *p;
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opts->mode = RAMFS_DEFAULT_MODE;
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while ((p = strsep(&data, ",")) != NULL) {
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if (!*p)
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continue;
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token = match_token(p, tokens, args);
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switch (token) {
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case Opt_mode:
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if (match_octal(&args[0], &option))
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return -EINVAL;
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opts->mode = option & S_IALLUGO;
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break;
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/*
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* We might like to report bad mount options here;
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* but traditionally ramfs has ignored all mount options,
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* and as it is used as a !CONFIG_SHMEM simple substitute
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* for tmpfs, better continue to ignore other mount options.
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*/
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}
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}
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return 0;
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}
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int ramfs_fill_super(struct super_block *sb, void *data, int silent)
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{
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struct ramfs_fs_info *fsi;
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struct inode *inode = NULL;
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struct dentry *root;
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int err;
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save_mount_options(sb, data);
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fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
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sb->s_fs_info = fsi;
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if (!fsi) {
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err = -ENOMEM;
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goto fail;
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}
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err = ramfs_parse_options(data, &fsi->mount_opts);
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if (err)
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goto fail;
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sb->s_maxbytes = MAX_LFS_FILESIZE;
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sb->s_blocksize = PAGE_CACHE_SIZE;
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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sb->s_magic = RAMFS_MAGIC;
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sb->s_op = &ramfs_ops;
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sb->s_time_gran = 1;
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inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
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if (!inode) {
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err = -ENOMEM;
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goto fail;
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}
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root = d_alloc_root(inode);
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sb->s_root = root;
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if (!root) {
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err = -ENOMEM;
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goto fail;
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}
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return 0;
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fail:
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kfree(fsi);
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sb->s_fs_info = NULL;
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iput(inode);
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return err;
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}
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struct dentry *ramfs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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return mount_nodev(fs_type, flags, data, ramfs_fill_super);
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}
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static struct dentry *rootfs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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return mount_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super);
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}
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static void ramfs_kill_sb(struct super_block *sb)
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{
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kfree(sb->s_fs_info);
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kill_litter_super(sb);
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}
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static struct file_system_type ramfs_fs_type = {
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.name = "ramfs",
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.mount = ramfs_mount,
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.kill_sb = ramfs_kill_sb,
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};
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static struct file_system_type rootfs_fs_type = {
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.name = "rootfs",
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.mount = rootfs_mount,
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.kill_sb = kill_litter_super,
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};
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static int __init init_ramfs_fs(void)
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{
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return register_filesystem(&ramfs_fs_type);
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}
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module_init(init_ramfs_fs)
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int __init init_rootfs(void)
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{
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int err;
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err = bdi_init(&ramfs_backing_dev_info);
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if (err)
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return err;
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err = register_filesystem(&rootfs_fs_type);
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if (err)
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bdi_destroy(&ramfs_backing_dev_info);
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return err;
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}
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