1 files changed, 287 insertions, 0 deletions
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
new file mode 100644
index 000000000000..bfc28abe1cb1
--- /dev/null
+++ b/fs/afs/mntpt.c
@@ -0,0 +1,287 @@
+/* mntpt.c: mountpoint management
+ *
+ * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/namespace.h>
+#include "super.h"
+#include "cell.h"
+#include "volume.h"
+#include "vnode.h"
+#include "internal.h"
+
+
+static struct dentry *afs_mntpt_lookup(struct inode *dir,
+				       struct dentry *dentry,
+				       struct nameidata *nd);
+static int afs_mntpt_open(struct inode *inode, struct file *file);
+static int afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
+
+struct file_operations afs_mntpt_file_operations = {
+	.open		= afs_mntpt_open,
+};
+
+struct inode_operations afs_mntpt_inode_operations = {
+	.lookup		= afs_mntpt_lookup,
+	.follow_link	= afs_mntpt_follow_link,
+	.readlink	= page_readlink,
+	.getattr	= afs_inode_getattr,
+};
+
+static LIST_HEAD(afs_vfsmounts);
+
+static void afs_mntpt_expiry_timed_out(struct afs_timer *timer);
+
+struct afs_timer_ops afs_mntpt_expiry_timer_ops = {
+	.timed_out	= afs_mntpt_expiry_timed_out,
+};
+
+struct afs_timer afs_mntpt_expiry_timer;
+
+unsigned long afs_mntpt_expiry_timeout = 20;
+
+/*****************************************************************************/
+/*
+ * check a symbolic link to see whether it actually encodes a mountpoint
+ * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
+ */
+int afs_mntpt_check_symlink(struct afs_vnode *vnode)
+{
+	struct page *page;
+	filler_t *filler;
+	size_t size;
+	char *buf;
+	int ret;
+
+	_enter("{%u,%u}", vnode->fid.vnode, vnode->fid.unique);
+
+	/* read the contents of the symlink into the pagecache */
+	filler = (filler_t *) AFS_VNODE_TO_I(vnode)->i_mapping->a_ops->readpage;
+
+	page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
+			       filler, NULL);
+	if (IS_ERR(page)) {
+		ret = PTR_ERR(page);
+		goto out;
+	}
+
+	ret = -EIO;
+	wait_on_page_locked(page);
+	buf = kmap(page);
+	if (!PageUptodate(page))
+		goto out_free;
+	if (PageError(page))
+		goto out_free;
+
+	/* examine the symlink's contents */
+	size = vnode->status.size;
+	_debug("symlink to %*.*s", size, (int) size, buf);
+
+	if (size > 2 &&
+	    (buf[0] == '%' || buf[0] == '#') &&
+	    buf[size - 1] == '.'
+	    ) {
+		_debug("symlink is a mountpoint");
+		spin_lock(&vnode->lock);
+		vnode->flags |= AFS_VNODE_MOUNTPOINT;
+		spin_unlock(&vnode->lock);
+	}
+
+	ret = 0;
+
+ out_free:
+	kunmap(page);
+	page_cache_release(page);
+ out:
+	_leave(" = %d", ret);
+	return ret;
+
+} /* end afs_mntpt_check_symlink() */
+
+/*****************************************************************************/
+/*
+ * no valid lookup procedure on this sort of dir
+ */
+static struct dentry *afs_mntpt_lookup(struct inode *dir,
+				       struct dentry *dentry,
+				       struct nameidata *nd)
+{
+	kenter("%p,%p{%p{%s},%s}",
+	       dir,
+	       dentry,
+	       dentry->d_parent,
+	       dentry->d_parent ?
+	       dentry->d_parent->d_name.name : (const unsigned char *) "",
+	       dentry->d_name.name);
+
+	return ERR_PTR(-EREMOTE);
+} /* end afs_mntpt_lookup() */
+
+/*****************************************************************************/
+/*
+ * no valid open procedure on this sort of dir
+ */
+static int afs_mntpt_open(struct inode *inode, struct file *file)
+{
+	kenter("%p,%p{%p{%s},%s}",
+	       inode, file,
+	       file->f_dentry->d_parent,
+	       file->f_dentry->d_parent ?
+	       file->f_dentry->d_parent->d_name.name :
+	       (const unsigned char *) "",
+	       file->f_dentry->d_name.name);
+
+	return -EREMOTE;
+} /* end afs_mntpt_open() */
+
+/*****************************************************************************/
+/*
+ * create a vfsmount to be automounted
+ */
+static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
+{
+	struct afs_super_info *super;
+	struct vfsmount *mnt;
+	struct page *page = NULL;
+	size_t size;
+	char *buf, *devname = NULL, *options = NULL;
+	filler_t *filler;
+	int ret;
+
+	kenter("{%s}", mntpt->d_name.name);
+
+	BUG_ON(!mntpt->d_inode);
+
+	ret = -EINVAL;
+	size = mntpt->d_inode->i_size;
+	if (size > PAGE_SIZE - 1)
+		goto error;
+
+	ret = -ENOMEM;
+	devname = (char *) get_zeroed_page(GFP_KERNEL);
+	if (!devname)
+		goto error;
+
+	options = (char *) get_zeroed_page(GFP_KERNEL);
+	if (!options)
+		goto error;
+
+	/* read the contents of the AFS special symlink */
+	filler = (filler_t *)mntpt->d_inode->i_mapping->a_ops->readpage;
+
+	page = read_cache_page(mntpt->d_inode->i_mapping, 0, filler, NULL);
+	if (IS_ERR(page)) {
+		ret = PTR_ERR(page);
+		goto error;
+	}
+
+	ret = -EIO;
+	wait_on_page_locked(page);
+	if (!PageUptodate(page) || PageError(page))
+		goto error;
+
+	buf = kmap(page);
+	memcpy(devname, buf, size);
+	kunmap(page);
+	page_cache_release(page);
+	page = NULL;
+
+	/* work out what options we want */
+	super = AFS_FS_S(mntpt->d_sb);
+	memcpy(options, "cell=", 5);
+	strcpy(options + 5, super->volume->cell->name);
+	if (super->volume->type == AFSVL_RWVOL)
+		strcat(options, ",rwpath");
+
+	/* try and do the mount */
+	kdebug("--- attempting mount %s -o %s ---", devname, options);
+	mnt = do_kern_mount("afs", 0, devname, options);
+	kdebug("--- mount result %p ---", mnt);
+
+	free_page((unsigned long) devname);
+	free_page((unsigned long) options);
+	kleave(" = %p", mnt);
+	return mnt;
+
+ error:
+	if (page)
+		page_cache_release(page);
+	if (devname)
+		free_page((unsigned long) devname);
+	if (options)
+		free_page((unsigned long) options);
+	kleave(" = %d", ret);
+	return ERR_PTR(ret);
+} /* end afs_mntpt_do_automount() */
+
+/*****************************************************************************/
+/*
+ * follow a link from a mountpoint directory, thus causing it to be mounted
+ */
+static int afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	struct vfsmount *newmnt;
+	struct dentry *old_dentry;
+	int err;
+
+	kenter("%p{%s},{%s:%p{%s}}",
+	       dentry,
+	       dentry->d_name.name,
+	       nd->mnt->mnt_devname,
+	       dentry,
+	       nd->dentry->d_name.name);
+
+	newmnt = afs_mntpt_do_automount(dentry);
+	if (IS_ERR(newmnt)) {
+		path_release(nd);
+		return PTR_ERR(newmnt);
+	}
+
+	old_dentry = nd->dentry;
+	nd->dentry = dentry;
+	err = do_add_mount(newmnt, nd, 0, &afs_vfsmounts);
+	nd->dentry = old_dentry;
+
+	path_release(nd);
+
+	if (!err) {
+		mntget(newmnt);
+		nd->mnt = newmnt;
+		dget(newmnt->mnt_root);
+		nd->dentry = newmnt->mnt_root;
+	}
+
+	kleave(" = %d", err);
+	return err;
+} /* end afs_mntpt_follow_link() */
+
+/*****************************************************************************/
+/*
+ * handle mountpoint expiry timer going off
+ */
+static void afs_mntpt_expiry_timed_out(struct afs_timer *timer)
+{
+	kenter("");
+
+	mark_mounts_for_expiry(&afs_vfsmounts);
+
+	afs_kafstimod_add_timer(&afs_mntpt_expiry_timer,
+				afs_mntpt_expiry_timeout * HZ);
+
+	kleave("");
+} /* end afs_mntpt_expiry_timed_out() */