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 .listxattr = afs_listxattr, 39 }; 40 41 const struct inode_operations afs_autocell_inode_operations = { 42 .getattr = afs_getattr, 43 }; 44 45 static LIST_HEAD(afs_vfsmounts); 46 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); 47 48 static unsigned long afs_mntpt_expiry_timeout = 10 * 60; 49 50 /* 51 * no valid lookup procedure on this sort of dir 52 */ 53 static struct dentry *afs_mntpt_lookup(struct inode *dir, 54 struct dentry *dentry, 55 unsigned int flags) 56 { 57 _enter("%p,%p{%pd2}", dir, dentry, dentry); 58 return ERR_PTR(-EREMOTE); 59 } 60 61 /* 62 * no valid open procedure on this sort of dir 63 */ 64 static int afs_mntpt_open(struct inode *inode, struct file *file) 65 { 66 _enter("%p,%p{%pD2}", inode, file, file); 67 return -EREMOTE; 68 } 69 70 /* 71 * create a vfsmount to be automounted 72 */ 73 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) 74 { 75 struct afs_super_info *super; 76 struct vfsmount *mnt; 77 struct afs_vnode *vnode; 78 struct page *page; 79 char *devname, *options; 80 bool rwpath = false; 81 int ret; 82 83 _enter("{%pd}", mntpt); 84 85 BUG_ON(!d_inode(mntpt)); 86 87 ret = -ENOMEM; 88 devname = (char *) get_zeroed_page(GFP_KERNEL); 89 if (!devname) 90 goto error_no_devname; 91 92 options = (char *) get_zeroed_page(GFP_KERNEL); 93 if (!options) 94 goto error_no_options; 95 96 vnode = AFS_FS_I(d_inode(mntpt)); 97 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) { 98 /* if the directory is a pseudo directory, use the d_name */ 99 static const char afs_root_cell[] = ":root.cell."; 100 unsigned size = mntpt->d_name.len; 101 102 ret = -ENOENT; 103 if (size < 2 || size > AFS_MAXCELLNAME) 104 goto error_no_page; 105 106 if (mntpt->d_name.name[0] == '.') { 107 devname[0] = '#'; 108 memcpy(devname + 1, mntpt->d_name.name, size - 1); 109 memcpy(devname + size, afs_root_cell, 110 sizeof(afs_root_cell)); 111 rwpath = true; 112 } else { 113 devname[0] = '%'; 114 memcpy(devname + 1, mntpt->d_name.name, size); 115 memcpy(devname + size + 1, afs_root_cell, 116 sizeof(afs_root_cell)); 117 } 118 } else { 119 /* read the contents of the AFS special symlink */ 120 loff_t size = i_size_read(d_inode(mntpt)); 121 char *buf; 122 123 ret = -EINVAL; 124 if (size > PAGE_SIZE - 1) 125 goto error_no_page; 126 127 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL); 128 if (IS_ERR(page)) { 129 ret = PTR_ERR(page); 130 goto error_no_page; 131 } 132 133 ret = -EIO; 134 if (PageError(page)) 135 goto error; 136 137 buf = kmap_atomic(page); 138 memcpy(devname, buf, size); 139 kunmap_atomic(buf); 140 put_page(page); 141 page = NULL; 142 } 143 144 /* work out what options we want */ 145 super = AFS_FS_S(mntpt->d_sb); 146 memcpy(options, "cell=", 5); 147 strcpy(options + 5, super->volume->cell->name); 148 if (super->volume->type == AFSVL_RWVOL || rwpath) 149 strcat(options, ",rwpath"); 150 151 /* try and do the mount */ 152 _debug("--- attempting mount %s -o %s ---", devname, options); 153 mnt = vfs_submount(mntpt, &afs_fs_type, devname, options); 154 _debug("--- mount result %p ---", mnt); 155 156 free_page((unsigned long) devname); 157 free_page((unsigned long) options); 158 _leave(" = %p", mnt); 159 return mnt; 160 161 error: 162 put_page(page); 163 error_no_page: 164 free_page((unsigned long) options); 165 error_no_options: 166 free_page((unsigned long) devname); 167 error_no_devname: 168 _leave(" = %d", ret); 169 return ERR_PTR(ret); 170 } 171 172 /* 173 * handle an automount point 174 */ 175 struct vfsmount *afs_d_automount(struct path *path) 176 { 177 struct vfsmount *newmnt; 178 179 _enter("{%pd}", path->dentry); 180 181 newmnt = afs_mntpt_do_automount(path->dentry); 182 if (IS_ERR(newmnt)) 183 return newmnt; 184 185 mntget(newmnt); /* prevent immediate expiration */ 186 mnt_set_expiry(newmnt, &afs_vfsmounts); 187 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 188 afs_mntpt_expiry_timeout * HZ); 189 _leave(" = %p", newmnt); 190 return newmnt; 191 } 192 193 /* 194 * handle mountpoint expiry timer going off 195 */ 196 static void afs_mntpt_expiry_timed_out(struct work_struct *work) 197 { 198 _enter(""); 199 200 if (!list_empty(&afs_vfsmounts)) { 201 mark_mounts_for_expiry(&afs_vfsmounts); 202 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 203 afs_mntpt_expiry_timeout * HZ); 204 } 205 206 _leave(""); 207 } 208 209 /* 210 * kill the AFS mountpoint timer if it's still running 211 */ 212 void afs_mntpt_kill_timer(void) 213 { 214 _enter(""); 215 216 ASSERT(list_empty(&afs_vfsmounts)); 217 cancel_delayed_work_sync(&afs_mntpt_expiry_timer); 218 } 219