1 /* mountpoint management 2 * 3 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/init.h> 15 #include <linux/fs.h> 16 #include <linux/pagemap.h> 17 #include <linux/mount.h> 18 #include <linux/namei.h> 19 #include <linux/gfp.h> 20 #include "internal.h" 21 22 23 static struct dentry *afs_mntpt_lookup(struct inode *dir, 24 struct dentry *dentry, 25 unsigned int flags); 26 static int afs_mntpt_open(struct inode *inode, struct file *file); 27 static void afs_mntpt_expiry_timed_out(struct work_struct *work); 28 29 const struct file_operations afs_mntpt_file_operations = { 30 .open = afs_mntpt_open, 31 .llseek = noop_llseek, 32 }; 33 34 const struct inode_operations afs_mntpt_inode_operations = { 35 .lookup = afs_mntpt_lookup, 36 .readlink = page_readlink, 37 .getattr = afs_getattr, 38 }; 39 40 const struct inode_operations afs_autocell_inode_operations = { 41 .getattr = afs_getattr, 42 }; 43 44 static LIST_HEAD(afs_vfsmounts); 45 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); 46 47 static unsigned long afs_mntpt_expiry_timeout = 10 * 60; 48 49 /* 50 * no valid lookup procedure on this sort of dir 51 */ 52 static struct dentry *afs_mntpt_lookup(struct inode *dir, 53 struct dentry *dentry, 54 unsigned int flags) 55 { 56 _enter("%p,%p{%pd2}", dir, dentry, dentry); 57 return ERR_PTR(-EREMOTE); 58 } 59 60 /* 61 * no valid open procedure on this sort of dir 62 */ 63 static int afs_mntpt_open(struct inode *inode, struct file *file) 64 { 65 _enter("%p,%p{%pD2}", inode, file, file); 66 return -EREMOTE; 67 } 68 69 /* 70 * create a vfsmount to be automounted 71 */ 72 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) 73 { 74 struct afs_super_info *super; 75 struct vfsmount *mnt; 76 struct afs_vnode *vnode; 77 struct page *page; 78 char *devname, *options; 79 bool rwpath = false; 80 int ret; 81 82 _enter("{%pd}", mntpt); 83 84 BUG_ON(!d_inode(mntpt)); 85 86 ret = -ENOMEM; 87 devname = (char *) get_zeroed_page(GFP_KERNEL); 88 if (!devname) 89 goto error_no_devname; 90 91 options = (char *) get_zeroed_page(GFP_KERNEL); 92 if (!options) 93 goto error_no_options; 94 95 vnode = AFS_FS_I(d_inode(mntpt)); 96 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) { 97 /* if the directory is a pseudo directory, use the d_name */ 98 static const char afs_root_cell[] = ":root.cell."; 99 unsigned size = mntpt->d_name.len; 100 101 ret = -ENOENT; 102 if (size < 2 || size > AFS_MAXCELLNAME) 103 goto error_no_page; 104 105 if (mntpt->d_name.name[0] == '.') { 106 devname[0] = '#'; 107 memcpy(devname + 1, mntpt->d_name.name, size - 1); 108 memcpy(devname + size, afs_root_cell, 109 sizeof(afs_root_cell)); 110 rwpath = true; 111 } else { 112 devname[0] = '%'; 113 memcpy(devname + 1, mntpt->d_name.name, size); 114 memcpy(devname + size + 1, afs_root_cell, 115 sizeof(afs_root_cell)); 116 } 117 } else { 118 /* read the contents of the AFS special symlink */ 119 loff_t size = i_size_read(d_inode(mntpt)); 120 char *buf; 121 122 ret = -EINVAL; 123 if (size > PAGE_SIZE - 1) 124 goto error_no_page; 125 126 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL); 127 if (IS_ERR(page)) { 128 ret = PTR_ERR(page); 129 goto error_no_page; 130 } 131 132 ret = -EIO; 133 if (PageError(page)) 134 goto error; 135 136 buf = kmap_atomic(page); 137 memcpy(devname, buf, size); 138 kunmap_atomic(buf); 139 put_page(page); 140 page = NULL; 141 } 142 143 /* work out what options we want */ 144 super = AFS_FS_S(mntpt->d_sb); 145 memcpy(options, "cell=", 5); 146 strcpy(options + 5, super->volume->cell->name); 147 if (super->volume->type == AFSVL_RWVOL || rwpath) 148 strcat(options, ",rwpath"); 149 150 /* try and do the mount */ 151 _debug("--- attempting mount %s -o %s ---", devname, options); 152 mnt = vfs_submount(mntpt, &afs_fs_type, devname, options); 153 _debug("--- mount result %p ---", mnt); 154 155 free_page((unsigned long) devname); 156 free_page((unsigned long) options); 157 _leave(" = %p", mnt); 158 return mnt; 159 160 error: 161 put_page(page); 162 error_no_page: 163 free_page((unsigned long) options); 164 error_no_options: 165 free_page((unsigned long) devname); 166 error_no_devname: 167 _leave(" = %d", ret); 168 return ERR_PTR(ret); 169 } 170 171 /* 172 * handle an automount point 173 */ 174 struct vfsmount *afs_d_automount(struct path *path) 175 { 176 struct vfsmount *newmnt; 177 178 _enter("{%pd}", path->dentry); 179 180 newmnt = afs_mntpt_do_automount(path->dentry); 181 if (IS_ERR(newmnt)) 182 return newmnt; 183 184 mntget(newmnt); /* prevent immediate expiration */ 185 mnt_set_expiry(newmnt, &afs_vfsmounts); 186 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 187 afs_mntpt_expiry_timeout * HZ); 188 _leave(" = %p", newmnt); 189 return newmnt; 190 } 191 192 /* 193 * handle mountpoint expiry timer going off 194 */ 195 static void afs_mntpt_expiry_timed_out(struct work_struct *work) 196 { 197 _enter(""); 198 199 if (!list_empty(&afs_vfsmounts)) { 200 mark_mounts_for_expiry(&afs_vfsmounts); 201 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 202 afs_mntpt_expiry_timeout * HZ); 203 } 204 205 _leave(""); 206 } 207 208 /* 209 * kill the AFS mountpoint timer if it's still running 210 */ 211 void afs_mntpt_kill_timer(void) 212 { 213 _enter(""); 214 215 ASSERT(list_empty(&afs_vfsmounts)); 216 cancel_delayed_work_sync(&afs_mntpt_expiry_timer); 217 } 218