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4d673da145
Support the AFS dynamic root which is a pseudo-volume that doesn't connect to any server resource, but rather is just a root directory that dynamically creates mountpoint directories where the name of such a directory is the name of the cell. Such a mount can be created thus: mount -t afs none /afs -o dyn Dynamic root superblocks aren't shared except by bind mounts and propagation. Cell root volumes can then be mounted by referring to them by name, e.g.: ls /afs/grand.central.org/ ls /afs/.grand.central.org/ The kernel will upcall to consult the DNS if the address wasn't supplied directly. Signed-off-by: David Howells <dhowells@redhat.com>
221 lines
5.2 KiB
C
221 lines
5.2 KiB
C
/* mountpoint management
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*
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* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/gfp.h>
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#include "internal.h"
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags);
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static int afs_mntpt_open(struct inode *inode, struct file *file);
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static void afs_mntpt_expiry_timed_out(struct work_struct *work);
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const struct file_operations afs_mntpt_file_operations = {
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.open = afs_mntpt_open,
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.llseek = noop_llseek,
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};
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const struct inode_operations afs_mntpt_inode_operations = {
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.lookup = afs_mntpt_lookup,
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.readlink = page_readlink,
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.getattr = afs_getattr,
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.listxattr = afs_listxattr,
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};
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const struct inode_operations afs_autocell_inode_operations = {
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.getattr = afs_getattr,
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};
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static LIST_HEAD(afs_vfsmounts);
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static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
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static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
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/*
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* no valid lookup procedure on this sort of dir
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*/
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags)
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{
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_enter("%p,%p{%pd2}", dir, dentry, dentry);
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return ERR_PTR(-EREMOTE);
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}
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/*
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* no valid open procedure on this sort of dir
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*/
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static int afs_mntpt_open(struct inode *inode, struct file *file)
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{
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_enter("%p,%p{%pD2}", inode, file, file);
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return -EREMOTE;
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}
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/*
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* create a vfsmount to be automounted
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*/
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static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
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{
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struct afs_super_info *as;
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struct vfsmount *mnt;
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struct afs_vnode *vnode;
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struct page *page;
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char *devname, *options;
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bool rwpath = false;
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int ret;
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_enter("{%pd}", mntpt);
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BUG_ON(!d_inode(mntpt));
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ret = -ENOMEM;
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devname = (char *) get_zeroed_page(GFP_KERNEL);
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if (!devname)
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goto error_no_devname;
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options = (char *) get_zeroed_page(GFP_KERNEL);
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if (!options)
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goto error_no_options;
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vnode = AFS_FS_I(d_inode(mntpt));
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if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
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/* if the directory is a pseudo directory, use the d_name */
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static const char afs_root_cell[] = ":root.cell.";
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unsigned size = mntpt->d_name.len;
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ret = -ENOENT;
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if (size < 2 || size > AFS_MAXCELLNAME)
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goto error_no_page;
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if (mntpt->d_name.name[0] == '.') {
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devname[0] = '%';
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memcpy(devname + 1, mntpt->d_name.name + 1, size - 1);
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memcpy(devname + size, afs_root_cell,
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sizeof(afs_root_cell));
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rwpath = true;
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} else {
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devname[0] = '#';
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memcpy(devname + 1, mntpt->d_name.name, size);
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memcpy(devname + size + 1, afs_root_cell,
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sizeof(afs_root_cell));
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}
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} else {
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/* read the contents of the AFS special symlink */
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loff_t size = i_size_read(d_inode(mntpt));
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char *buf;
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ret = -EINVAL;
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if (size > PAGE_SIZE - 1)
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goto error_no_page;
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page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
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if (IS_ERR(page)) {
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ret = PTR_ERR(page);
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goto error_no_page;
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}
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ret = -EIO;
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if (PageError(page))
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goto error;
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buf = kmap_atomic(page);
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memcpy(devname, buf, size);
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kunmap_atomic(buf);
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put_page(page);
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page = NULL;
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}
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/* work out what options we want */
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as = AFS_FS_S(mntpt->d_sb);
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if (as->cell) {
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memcpy(options, "cell=", 5);
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strcpy(options + 5, as->cell->name);
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if ((as->volume && as->volume->type == AFSVL_RWVOL) || rwpath)
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strcat(options, ",rwpath");
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}
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/* try and do the mount */
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_debug("--- attempting mount %s -o %s ---", devname, options);
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mnt = vfs_submount(mntpt, &afs_fs_type, devname, options);
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_debug("--- mount result %p ---", mnt);
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free_page((unsigned long) devname);
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free_page((unsigned long) options);
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_leave(" = %p", mnt);
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return mnt;
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error:
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put_page(page);
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error_no_page:
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free_page((unsigned long) options);
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error_no_options:
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free_page((unsigned long) devname);
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error_no_devname:
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_leave(" = %d", ret);
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return ERR_PTR(ret);
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}
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/*
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* handle an automount point
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*/
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struct vfsmount *afs_d_automount(struct path *path)
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{
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struct vfsmount *newmnt;
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_enter("{%pd}", path->dentry);
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newmnt = afs_mntpt_do_automount(path->dentry);
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if (IS_ERR(newmnt))
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return newmnt;
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mntget(newmnt); /* prevent immediate expiration */
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mnt_set_expiry(newmnt, &afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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_leave(" = %p", newmnt);
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return newmnt;
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}
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/*
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* handle mountpoint expiry timer going off
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*/
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static void afs_mntpt_expiry_timed_out(struct work_struct *work)
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{
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_enter("");
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if (!list_empty(&afs_vfsmounts)) {
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mark_mounts_for_expiry(&afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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}
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_leave("");
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}
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/*
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* kill the AFS mountpoint timer if it's still running
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*/
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void afs_mntpt_kill_timer(void)
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{
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_enter("");
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ASSERT(list_empty(&afs_vfsmounts));
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cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
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}
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