diff options
Diffstat (limited to 'fs/afs/mntpt.c')
| -rw-r--r-- | fs/afs/mntpt.c | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c new file mode 100644 index 00000000..298cf891 --- /dev/null +++ b/fs/afs/mntpt.c @@ -0,0 +1,284 @@ +/* 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, + struct nameidata *nd); +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, + struct nameidata *nd) +{ + _enter("%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); +} + +/* + * no valid open procedure on this sort of dir + */ +static int afs_mntpt_open(struct inode *inode, struct file *file) +{ + _enter("%p,%p{%p{%s},%s}", + inode, file, + file->f_path.dentry->d_parent, + file->f_path.dentry->d_parent ? + file->f_path.dentry->d_parent->d_name.name : + (const unsigned char *) "", + file->f_path.dentry->d_name.name); + + 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("{%s}", mntpt->d_name.name); + + BUG_ON(!mntpt->d_inode); + + 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(mntpt->d_inode); + 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(mntpt->d_inode); + char *buf; + + ret = -EINVAL; + if (size > PAGE_SIZE - 1) + goto error_no_page; + + page = read_mapping_page(mntpt->d_inode->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("{%s}", path->dentry->d_name.name); + + 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); +} |