diff options
Diffstat (limited to 'fs/afs/mntpt.c')
| -rw-r--r-- | fs/afs/mntpt.c | 287 |
1 files changed, 287 insertions, 0 deletions
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c new file mode 100644 index 0000000..bfc28ab --- /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() */ |
