1 files changed, 270 insertions, 0 deletions
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
new file mode 100644
index 000000000..ccd0b212e
--- /dev/null
+++ b/fs/afs/mntpt.c
@@ -0,0 +1,270 @@
+/* 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/fs.h>
+#include <linux/pagemap.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/gfp.h>
+#include "internal.h"
+
+
+static struct dentry *afs_mntpt_lookup(struct inode *dir,
+				       struct dentry *dentry,
+				       unsigned int flags);
+static int afs_mntpt_open(struct inode *inode, struct file *file);
+static void afs_mntpt_expiry_timed_out(struct work_struct *work);
+
+const struct file_operations afs_mntpt_file_operations = {
+	.open		= afs_mntpt_open,
+	.llseek		= noop_llseek,
+};
+
+const struct inode_operations afs_mntpt_inode_operations = {
+	.lookup		= afs_mntpt_lookup,
+	.readlink	= page_readlink,
+	.getattr	= afs_getattr,
+};
+
+const struct inode_operations afs_autocell_inode_operations = {
+	.getattr	= afs_getattr,
+};
+
+static LIST_HEAD(afs_vfsmounts);
+static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
+
+static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
+
+/*
+ * 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 key *key)
+{
+	struct page *page;
+	size_t size;
+	char *buf;
+	int ret;
+
+	_enter("{%x:%u,%u}",
+	       vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
+
+	/* read the contents of the symlink into the pagecache */
+	page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
+			       afs_page_filler, key);
+	if (IS_ERR(page)) {
+		ret = PTR_ERR(page);
+		goto out;
+	}
+
+	ret = -EIO;
+	if (PageError(page))
+		goto out_free;
+
+	buf = kmap(page);
+
+	/* examine the symlink's contents */
+	size = vnode->status.size;
+	_debug("symlink to %*.*s", (int) size, (int) size, buf);
+
+	if (size > 2 &&
+	    (buf[0] == '%' || buf[0] == '#') &&
+	    buf[size - 1] == '.'
+	    ) {
+		_debug("symlink is a mountpoint");
+		spin_lock(&vnode->lock);
+		set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+		vnode->vfs_inode.i_flags |= S_AUTOMOUNT;
+		spin_unlock(&vnode->lock);
+	}
+
+	ret = 0;
+
+	kunmap(page);
+out_free:
+	page_cache_release(page);
+out:
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * no valid lookup procedure on this sort of dir
+ */
+static struct dentry *afs_mntpt_lookup(struct inode *dir,
+				       struct dentry *dentry,
+				       unsigned int flags)
+{
+	_enter("%p,%p{%pd2}", dir, dentry, dentry);
+	return ERR_PTR(-EREMOTE);
+}
+
+/*
+ * no valid open procedure on this sort of dir
+ */
+static int afs_mntpt_open(struct inode *inode, struct file *file)
+{
+	_enter("%p,%p{%pD2}", inode, file, file);
+	return -EREMOTE;
+}
+
+/*
+ * 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 afs_vnode *vnode;
+	struct page *page;
+	char *devname, *options;
+	bool rwpath = false;
+	int ret;
+
+	_enter("{%pd}", mntpt);
+
+	BUG_ON(!d_inode(mntpt));
+
+	ret = -ENOMEM;
+	devname = (char *) get_zeroed_page(GFP_KERNEL);
+	if (!devname)
+		goto error_no_devname;
+
+	options = (char *) get_zeroed_page(GFP_KERNEL);
+	if (!options)
+		goto error_no_options;
+
+	vnode = AFS_FS_I(d_inode(mntpt));
+	if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
+		/* if the directory is a pseudo directory, use the d_name */
+		static const char afs_root_cell[] = ":root.cell.";
+		unsigned size = mntpt->d_name.len;
+
+		ret = -ENOENT;
+		if (size < 2 || size > AFS_MAXCELLNAME)
+			goto error_no_page;
+
+		if (mntpt->d_name.name[0] == '.') {
+			devname[0] = '#';
+			memcpy(devname + 1, mntpt->d_name.name, size - 1);
+			memcpy(devname + size, afs_root_cell,
+			       sizeof(afs_root_cell));
+			rwpath = true;
+		} else {
+			devname[0] = '%';
+			memcpy(devname + 1, mntpt->d_name.name, size);
+			memcpy(devname + size + 1, afs_root_cell,
+			       sizeof(afs_root_cell));
+		}
+	} else {
+		/* read the contents of the AFS special symlink */
+		loff_t size = i_size_read(d_inode(mntpt));
+		char *buf;
+
+		ret = -EINVAL;
+		if (size > PAGE_SIZE - 1)
+			goto error_no_page;
+
+		page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
+		if (IS_ERR(page)) {
+			ret = PTR_ERR(page);
+			goto error_no_page;
+		}
+
+		ret = -EIO;
+		if (PageError(page))
+			goto error;
+
+		buf = kmap_atomic(page);
+		memcpy(devname, buf, size);
+		kunmap_atomic(buf);
+		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 || rwpath)
+		strcat(options, ",rwpath");
+
+	/* try and do the mount */
+	_debug("--- attempting mount %s -o %s ---", devname, options);
+	mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
+	_debug("--- mount result %p ---", mnt);
+
+	free_page((unsigned long) devname);
+	free_page((unsigned long) options);
+	_leave(" = %p", mnt);
+	return mnt;
+
+error:
+	page_cache_release(page);
+error_no_page:
+	free_page((unsigned long) options);
+error_no_options:
+	free_page((unsigned long) devname);
+error_no_devname:
+	_leave(" = %d", ret);
+	return ERR_PTR(ret);
+}
+
+/*
+ * handle an automount point
+ */
+struct vfsmount *afs_d_automount(struct path *path)
+{
+	struct vfsmount *newmnt;
+
+	_enter("{%pd}", path->dentry);
+
+	newmnt = afs_mntpt_do_automount(path->dentry);
+	if (IS_ERR(newmnt))
+		return newmnt;
+
+	mntget(newmnt); /* prevent immediate expiration */
+	mnt_set_expiry(newmnt, &afs_vfsmounts);
+	queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
+			   afs_mntpt_expiry_timeout * HZ);
+	_leave(" = %p", newmnt);
+	return newmnt;
+}
+
+/*
+ * handle mountpoint expiry timer going off
+ */
+static void afs_mntpt_expiry_timed_out(struct work_struct *work)
+{
+	_enter("");
+
+	if (!list_empty(&afs_vfsmounts)) {
+		mark_mounts_for_expiry(&afs_vfsmounts);
+		queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
+				   afs_mntpt_expiry_timeout * HZ);
+	}
+
+	_leave("");
+}
+
+/*
+ * kill the AFS mountpoint timer if it's still running
+ */
+void afs_mntpt_kill_timer(void)
+{
+	_enter("");
+
+	ASSERT(list_empty(&afs_vfsmounts));
+	cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
+}