1 files changed, 299 insertions, 0 deletions
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
new file mode 100644
index 000000000..f368a1690
--- /dev/null
+++ b/fs/ramfs/inode.c
@@ -0,0 +1,299 @@
+/*
+ * 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/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/ramfs.h>
+#include <linux/sched.h>
+#include <linux/parser.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+struct ramfs_mount_opts {
+	umode_t mode;
+};
+
+struct ramfs_fs_info {
+	struct ramfs_mount_opts mount_opts;
+};
+
+#define RAMFS_DEFAULT_MODE	0755
+
+static const struct super_operations ramfs_ops;
+static const struct inode_operations ramfs_dir_inode_operations;
+
+struct inode *ramfs_get_inode(struct super_block *sb,
+				const struct inode *dir, umode_t mode, dev_t dev)
+{
+	struct inode * inode = new_inode(sb);
+
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode_init_owner(&init_user_ns, inode, dir, mode);
+		inode->i_mapping->a_ops = &ram_aops;
+		mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
+		mapping_set_unevictable(inode->i_mapping);
+		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
+		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) */
+			inc_nlink(inode);
+			break;
+		case S_IFLNK:
+			inode->i_op = &page_symlink_inode_operations;
+			inode_nohighmem(inode);
+			break;
+		}
+	}
+	return inode;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+/* SMP-safe */
+static int
+ramfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+	    struct dentry *dentry, umode_t mode, dev_t dev)
+{
+	struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev);
+	int error = -ENOSPC;
+
+	if (inode) {
+		d_instantiate(dentry, inode);
+		dget(dentry);	/* Extra count - pin the dentry in core */
+		error = 0;
+		dir->i_mtime = dir->i_ctime = current_time(dir);
+	}
+	return error;
+}
+
+static int ramfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode)
+{
+	int retval = ramfs_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0);
+	if (!retval)
+		inc_nlink(dir);
+	return retval;
+}
+
+static int ramfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, umode_t mode, bool excl)
+{
+	return ramfs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0);
+}
+
+static int ramfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+			 struct dentry *dentry, const char *symname)
+{
+	struct inode *inode;
+	int error = -ENOSPC;
+
+	inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
+	if (inode) {
+		int l = strlen(symname)+1;
+		error = page_symlink(inode, symname, l);
+		if (!error) {
+			d_instantiate(dentry, inode);
+			dget(dentry);
+			dir->i_mtime = dir->i_ctime = current_time(dir);
+		} else
+			iput(inode);
+	}
+	return error;
+}
+
+static int ramfs_tmpfile(struct user_namespace *mnt_userns,
+			 struct inode *dir, struct file *file, umode_t mode)
+{
+	struct inode *inode;
+
+	inode = ramfs_get_inode(dir->i_sb, dir, mode, 0);
+	if (!inode)
+		return -ENOSPC;
+	d_tmpfile(file, inode);
+	return finish_open_simple(file, 0);
+}
+
+static const 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,
+	.tmpfile	= ramfs_tmpfile,
+};
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int ramfs_show_options(struct seq_file *m, struct dentry *root)
+{
+	struct ramfs_fs_info *fsi = root->d_sb->s_fs_info;
+
+	if (fsi->mount_opts.mode != RAMFS_DEFAULT_MODE)
+		seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
+	return 0;
+}
+
+static const struct super_operations ramfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+	.show_options	= ramfs_show_options,
+};
+
+enum ramfs_param {
+	Opt_mode,
+};
+
+const struct fs_parameter_spec ramfs_fs_parameters[] = {
+	fsparam_u32oct("mode",	Opt_mode),
+	{}
+};
+
+static int ramfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct fs_parse_result result;
+	struct ramfs_fs_info *fsi = fc->s_fs_info;
+	int opt;
+
+	opt = fs_parse(fc, ramfs_fs_parameters, param, &result);
+	if (opt == -ENOPARAM) {
+		opt = vfs_parse_fs_param_source(fc, param);
+		if (opt != -ENOPARAM)
+			return opt;
+		/*
+		 * We might like to report bad mount options here;
+		 * but traditionally ramfs has ignored all mount options,
+		 * and as it is used as a !CONFIG_SHMEM simple substitute
+		 * for tmpfs, better continue to ignore other mount options.
+		 */
+		return 0;
+	}
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_mode:
+		fsi->mount_opts.mode = result.uint_32 & S_IALLUGO;
+		break;
+	}
+
+	return 0;
+}
+
+static int ramfs_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct ramfs_fs_info *fsi = sb->s_fs_info;
+	struct inode *inode;
+
+	sb->s_maxbytes		= MAX_LFS_FILESIZE;
+	sb->s_blocksize		= PAGE_SIZE;
+	sb->s_blocksize_bits	= PAGE_SHIFT;
+	sb->s_magic		= RAMFS_MAGIC;
+	sb->s_op		= &ramfs_ops;
+	sb->s_time_gran		= 1;
+
+	inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int ramfs_get_tree(struct fs_context *fc)
+{
+	return get_tree_nodev(fc, ramfs_fill_super);
+}
+
+static void ramfs_free_fc(struct fs_context *fc)
+{
+	kfree(fc->s_fs_info);
+}
+
+static const struct fs_context_operations ramfs_context_ops = {
+	.free		= ramfs_free_fc,
+	.parse_param	= ramfs_parse_param,
+	.get_tree	= ramfs_get_tree,
+};
+
+int ramfs_init_fs_context(struct fs_context *fc)
+{
+	struct ramfs_fs_info *fsi;
+
+	fsi = kzalloc(sizeof(*fsi), GFP_KERNEL);
+	if (!fsi)
+		return -ENOMEM;
+
+	fsi->mount_opts.mode = RAMFS_DEFAULT_MODE;
+	fc->s_fs_info = fsi;
+	fc->ops = &ramfs_context_ops;
+	return 0;
+}
+
+void ramfs_kill_sb(struct super_block *sb)
+{
+	kfree(sb->s_fs_info);
+	kill_litter_super(sb);
+}
+
+static struct file_system_type ramfs_fs_type = {
+	.name		= "ramfs",
+	.init_fs_context = ramfs_init_fs_context,
+	.parameters	= ramfs_fs_parameters,
+	.kill_sb	= ramfs_kill_sb,
+	.fs_flags	= FS_USERNS_MOUNT,
+};
+
+static int __init init_ramfs_fs(void)
+{
+	return register_filesystem(&ramfs_fs_type);
+}
+fs_initcall(init_ramfs_fs);