patch-2.4.22 linux-2.4.22/arch/ia64/sn/io/hwgfs/ramfs.c

• Lines: 342
• Date: 2003-08-25 04:44:39.000000000 -0700
• Orig file: linux-2.4.21/arch/ia64/sn/io/hwgfs/ramfs.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.21/arch/ia64/sn/io/hwgfs/ramfs.c linux-2.4.22/arch/ia64/sn/io/hwgfs/ramfs.c
@@ -0,0 +1,341 @@
+/* $Id$
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1992 - 1997, 2000-2003 Silicon Graphics, Inc. All rights reserved.
+ */
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/machvec.h>
+
+/* some random number */
+#define HWGFS_MAGIC	0x12061983
+
+static struct super_operations hwgfs_ops;
+static struct address_space_operations hwgfs_aops;
+static struct file_operations hwgfs_file_operations;
+static struct inode_operations hwgfs_dir_inode_operations;
+
+static int hwgfs_statfs(struct super_block *sb, struct statfs *buf)
+{
+	buf->f_type = HWGFS_MAGIC;
+	buf->f_bsize = PAGE_CACHE_SIZE;
+	buf->f_namelen = 255;
+	return 0;
+}
+
+/*
+ * Lookup the data. This is trivial - if the dentry didn't already
+ * exist, we know it is negative.
+ */
+static struct dentry * hwgfs_lookup(struct inode *dir, struct dentry *dentry)
+{
+	d_add(dentry, NULL);
+	return NULL;
+}
+
+/*
+ * Read a page. Again trivial. If it didn't already exist
+ * in the page cache, it is zero-filled.
+ */
+static int hwgfs_readpage(struct file *file, struct page * page)
+{
+	if (!Page_Uptodate(page)) {
+		memset(kmap(page), 0, PAGE_CACHE_SIZE);
+		kunmap(page);
+		flush_dcache_page(page);
+		SetPageUptodate(page);
+	}
+	UnlockPage(page);
+	return 0;
+}
+
+static int hwgfs_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
+{
+	void *addr = kmap(page);
+	if (!Page_Uptodate(page)) {
+		memset(addr, 0, PAGE_CACHE_SIZE);
+		flush_dcache_page(page);
+		SetPageUptodate(page);
+	}
+	SetPageDirty(page);
+	return 0;
+}
+
+static int hwgfs_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to)
+{
+	struct inode *inode = page->mapping->host;
+	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+
+	kunmap(page);
+	if (pos > inode->i_size)
+		inode->i_size = pos;
+	return 0;
+}
+
+struct inode *hwgfs_get_inode(struct super_block *sb, int mode, int 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_rdev = NODEV;
+		inode->i_mapping->a_ops = &hwgfs_aops;
+		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_fop = &hwgfs_file_operations;
+			break;
+		case S_IFDIR:
+			inode->i_op = &hwgfs_dir_inode_operations;
+			inode->i_fop = &dcache_dir_ops;
+			break;
+		case S_IFLNK:
+			inode->i_op = &page_symlink_inode_operations;
+			break;
+		}
+	}
+	return inode;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+static int hwgfs_mknod(struct inode *dir, struct dentry *dentry, int mode, int dev)
+{
+	struct inode * inode = hwgfs_get_inode(dir->i_sb, mode, dev);
+	int error = -ENOSPC;
+
+	if (inode) {
+		d_instantiate(dentry, inode);
+		dget(dentry);		/* Extra count - pin the dentry in core */
+		error = 0;
+	}
+	return error;
+}
+
+static int hwgfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
+{
+	return hwgfs_mknod(dir, dentry, mode | S_IFDIR, 0);
+}
+
+static int hwgfs_create(struct inode *dir, struct dentry *dentry, int mode)
+{
+	return hwgfs_mknod(dir, dentry, mode | S_IFREG, 0);
+}
+
+/*
+ * Link a file..
+ */
+static int hwgfs_link(struct dentry *old_dentry, struct inode * dir, struct dentry * dentry)
+{
+	struct inode *inode = old_dentry->d_inode;
+
+	if (S_ISDIR(inode->i_mode))
+		return -EPERM;
+
+	inode->i_nlink++;
+	atomic_inc(&inode->i_count);	/* New dentry reference */
+	dget(dentry);		/* Extra pinning count for the created dentry */
+	d_instantiate(dentry, inode);
+	return 0;
+}
+
+static inline int hwgfs_positive(struct dentry *dentry)
+{
+	return dentry->d_inode && !d_unhashed(dentry);
+}
+
+/*
+ * Check that a directory is empty (this works
+ * for regular files too, they'll just always be
+ * considered empty..).
+ *
+ * Note that an empty directory can still have
+ * children, they just all have to be negative..
+ */
+static int hwgfs_empty(struct dentry *dentry)
+{
+	struct list_head *list;
+
+	spin_lock(&dcache_lock);
+	list = dentry->d_subdirs.next;
+
+	while (list != &dentry->d_subdirs) {
+		struct dentry *de = list_entry(list, struct dentry, d_child);
+
+		if (hwgfs_positive(de)) {
+			spin_unlock(&dcache_lock);
+			return 0;
+		}
+		list = list->next;
+	}
+	spin_unlock(&dcache_lock);
+	return 1;
+}
+
+/*
+ * This works for both directories and regular files.
+ * (non-directories will always have empty subdirs)
+ */
+static int hwgfs_unlink(struct inode * dir, struct dentry *dentry)
+{
+	int retval = -ENOTEMPTY;
+
+	if (hwgfs_empty(dentry)) {
+		struct inode *inode = dentry->d_inode;
+
+		inode->i_nlink--;
+		dput(dentry);			/* Undo the count from "create" - this does all the work */
+		retval = 0;
+	}
+	return retval;
+}
+
+#define hwgfs_rmdir hwgfs_unlink
+
+/*
+ * The VFS layer already does all the dentry stuff for rename,
+ * we just have to decrement the usage count for the target if
+ * it exists so that the VFS layer correctly free's it when it
+ * gets overwritten.
+ */
+static int hwgfs_rename(struct inode * old_dir, struct dentry *old_dentry, struct inode * new_dir,struct dentry *new_dentry)
+{
+	int error = -ENOTEMPTY;
+
+	if (hwgfs_empty(new_dentry)) {
+		struct inode *inode = new_dentry->d_inode;
+		if (inode) {
+			inode->i_nlink--;
+			dput(new_dentry);
+		}
+		error = 0;
+	}
+	return error;
+}
+
+static int hwgfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
+{
+	int error;
+
+	error = hwgfs_mknod(dir, dentry, S_IFLNK | S_IRWXUGO, 0);
+	if (!error) {
+		int l = strlen(symname)+1;
+		struct inode *inode = dentry->d_inode;
+		error = block_symlink(inode, symname, l);
+	}
+	return error;
+}
+
+static int hwgfs_sync_file(struct file * file, struct dentry *dentry, int datasync)
+{
+	return 0;
+}
+
+static struct address_space_operations hwgfs_aops = {
+	.readpage	= hwgfs_readpage,
+	.writepage	= fail_writepage,
+	.prepare_write	= hwgfs_prepare_write,
+	.commit_write	= hwgfs_commit_write
+};
+
+static struct file_operations hwgfs_file_operations = {
+	.read		= generic_file_read,
+	.write		= generic_file_write,
+	.mmap		= generic_file_mmap,
+	.fsync		= hwgfs_sync_file,
+};
+
+static struct inode_operations hwgfs_dir_inode_operations = {
+	.create		= hwgfs_create,
+	.lookup		= hwgfs_lookup,
+	.link		= hwgfs_link,
+	.unlink		= hwgfs_unlink,
+	.symlink	= hwgfs_symlink,
+	.mkdir		= hwgfs_mkdir,
+	.rmdir		= hwgfs_rmdir,
+	.mknod		= hwgfs_mknod,
+	.rename		= hwgfs_rename,
+};
+
+static struct super_operations hwgfs_ops = {
+	.statfs		= hwgfs_statfs,
+	.put_inode	= force_delete,
+};
+
+static struct super_block *hwgfs_read_super(struct super_block * sb, void * data, int silent)
+{
+	struct inode * inode;
+	struct dentry * root;
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = HWGFS_MAGIC;
+	sb->s_op = &hwgfs_ops;
+	inode = hwgfs_get_inode(sb, S_IFDIR | 0755, 0);
+	if (!inode)
+		return NULL;
+
+	root = d_alloc_root(inode);
+	if (!root) {
+		iput(inode);
+		return NULL;
+	}
+	sb->s_root = root;
+	return sb;
+}
+
+static struct file_system_type hwgfs_fs_type = {
+	.owner			= THIS_MODULE,
+	.name			= "hwgfs",
+	.read_super		= hwgfs_read_super,
+	.fs_flags		= FS_SINGLE|FS_LITTER,
+};
+
+struct vfsmount *hwgfs_vfsmount;
+
+int __init init_hwgfs_fs(void)
+{
+	int error;
+
+	if (!ia64_platform_is("sn2"))
+		return -ENODEV;
+
+	error = register_filesystem(&hwgfs_fs_type);
+	if (error)
+		return error;
+
+	hwgfs_vfsmount = kern_mount(&hwgfs_fs_type);
+	if (IS_ERR(hwgfs_vfsmount))
+		goto fail;
+	return 0;
+
+fail:
+	unregister_filesystem(&hwgfs_fs_type);
+	return PTR_ERR(hwgfs_vfsmount);
+}
+
+static void __exit exit_hwgfs_fs(void)
+{
+	unregister_filesystem(&hwgfs_fs_type);
+}
+
+MODULE_LICENSE("GPL");
+
+module_init(init_hwgfs_fs)
+module_exit(exit_hwgfs_fs)