2 files changed, 253 insertions, 0 deletions

diff --git a/fs/ramfs/Makefile b/fs/ramfs/Makefile
new file mode 100644
index 000000000000..f096f3007091
--- /dev/null
+++ b/fs/ramfs/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for the linux ramfs routines.
+#
+
+obj-$(CONFIG_RAMFS) += ramfs.o
+
+ramfs-objs := inode.o
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
new file mode 100644
index 000000000000..0a88917605ae
--- /dev/null
+++ b/fs/ramfs/inode.c
@@ -0,0 +1,246 @@
+/*
+ * 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/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/ramfs.h>
+
+#include <asm/uaccess.h>
+
+/* some random number */
+#define RAMFS_MAGIC     0x858458f6
+
+static struct super_operations ramfs_ops;
+static struct address_space_operations ramfs_aops;
+static struct inode_operations ramfs_file_inode_operations;
+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_blksize = PAGE_CACHE_SIZE;
+                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;
+        }
+        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);
+                } else
+                        iput(inode);
+        }
+        return error;
+}
+
+static struct address_space_operations ramfs_aops = {
+        .readpage       = simple_readpage,
+        .prepare_write  = simple_prepare_write,
+        .commit_write   = simple_commit_write
+};
+
+struct file_operations ramfs_file_operations = {
+        .read           = generic_file_read,
+        .write          = generic_file_write,
+        .mmap           = generic_file_mmap,
+        .fsync          = simple_sync_file,
+        .sendfile       = generic_file_sendfile,
+        .llseek         = generic_file_llseek,
+};
+
+static struct inode_operations ramfs_file_inode_operations = {
+        .getattr        = simple_getattr,
+};
+
+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;
+}
+
+struct super_block *ramfs_get_sb(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *data)
+{
+        return get_sb_nodev(fs_type, flags, data, ramfs_fill_super);
+}
+
+static struct super_block *rootfs_get_sb(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *data)
+{
+        return get_sb_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super);
+}
+
+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");