/* 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 void *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 void *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 (void *)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_PTR(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() */