fs/afs/mntpt.c

   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 <linux/fs_context.h>
  21 #include "internal.h"
  22
  23
  24 static struct dentry *afs_mntpt_lookup(struct inode *dir,
  25                                        struct dentry *dentry,
  26                                        unsigned int flags);
  27 static int afs_mntpt_open(struct inode *inode, struct file *file);
  28 static void afs_mntpt_expiry_timed_out(struct work_struct *work);
  29
  30 const struct file_operations afs_mntpt_file_operations = {
  31         .open           = afs_mntpt_open,
  32         .llseek         = noop_llseek,
  33 };
  34
  35 const struct inode_operations afs_mntpt_inode_operations = {
  36         .lookup         = afs_mntpt_lookup,
  37         .readlink       = page_readlink,
  38         .getattr        = afs_getattr,
  39         .listxattr      = afs_listxattr,
  40 };
  41
  42 const struct inode_operations afs_autocell_inode_operations = {
  43         .getattr        = afs_getattr,
  44 };
  45
  46 static LIST_HEAD(afs_vfsmounts);
  47 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
  48
  49 static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
  50
  51 static const char afs_root_volume[] = "root.cell";
  52
  53 /*
  54  * no valid lookup procedure on this sort of dir
  55  */
  56 static struct dentry *afs_mntpt_lookup(struct inode *dir,
  57                                        struct dentry *dentry,
  58                                        unsigned int flags)
  59 {
  60         _enter("%p,%p{%pd2}", dir, dentry, dentry);
  61         return ERR_PTR(-EREMOTE);
  62 }
  63
  64 /*
  65  * no valid open procedure on this sort of dir
  66  */
  67 static int afs_mntpt_open(struct inode *inode, struct file *file)
  68 {
  69         _enter("%p,%p{%pD2}", inode, file, file);
  70         return -EREMOTE;
  71 }
  72
  73 /*
  74  * Set the parameters for the proposed superblock.
  75  */
  76 static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
  77 {
  78         struct afs_fs_context *ctx = fc->fs_private;
  79         struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
  80         struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
  81         struct afs_cell *cell;
  82         const char *p;
  83         int ret;
  84
  85         if (fc->net_ns != src_as->net_ns) {
  86                 put_net(fc->net_ns);
  87                 fc->net_ns = get_net(src_as->net_ns);
  88         }
  89
  90         if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
  91                 ctx->type = AFSVL_RWVOL;
  92                 ctx->force = true;
  93         }
  94         if (ctx->cell) {
  95                 afs_put_cell(ctx->net, ctx->cell);
  96                 ctx->cell = NULL;
  97         }
  98         if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
  99                 /* if the directory is a pseudo directory, use the d_name */
 100                 unsigned size = mntpt->d_name.len;
 101
 102                 if (size < 2)
 103                         return -ENOENT;
 104
 105                 p = mntpt->d_name.name;
 106                 if (mntpt->d_name.name[0] == '.') {
 107                         size--;
 108                         p++;
 109                         ctx->type = AFSVL_RWVOL;
 110                         ctx->force = true;
 111                 }
 112                 if (size > AFS_MAXCELLNAME)
 113                         return -ENAMETOOLONG;
 114
 115                 cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
 116                 if (IS_ERR(cell)) {
 117                         pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
 118                         return PTR_ERR(cell);
 119                 }
 120                 ctx->cell = cell;
 121
 122                 ctx->volname = afs_root_volume;
 123                 ctx->volnamesz = sizeof(afs_root_volume) - 1;
 124         } else {
 125                 /* read the contents of the AFS special symlink */
 126                 struct page *page;
 127                 loff_t size = i_size_read(d_inode(mntpt));
 128                 char *buf;
 129
 130                 if (src_as->cell)
 131                         ctx->cell = afs_get_cell(src_as->cell);
 132
 133                 if (size > PAGE_SIZE - 1)
 134                         return -EINVAL;
 135
 136                 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
 137                 if (IS_ERR(page))
 138                         return PTR_ERR(page);
 139
 140                 if (PageError(page)) {
 141                         ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt);
 142                         put_page(page);
 143                         return ret;
 144                 }
 145
 146                 buf = kmap(page);
 147                 ret = vfs_parse_fs_string(fc, "source", buf, size);
 148                 kunmap(page);
 149                 put_page(page);
 150                 if (ret < 0)
 151                         return ret;
 152         }
 153
 154         return 0;
 155 }
 156
 157 /*
 158  * create a vfsmount to be automounted
 159  */
 160 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
 161 {
 162         struct fs_context *fc;
 163         struct vfsmount *mnt;
 164         int ret;
 165
 166         BUG_ON(!d_inode(mntpt));
 167
 168         fc = fs_context_for_submount(&afs_fs_type, mntpt);
 169         if (IS_ERR(fc))
 170                 return ERR_CAST(fc);
 171
 172         ret = afs_mntpt_set_params(fc, mntpt);
 173         if (!ret)
 174                 mnt = fc_mount(fc);
 175         else
 176                 mnt = ERR_PTR(ret);
 177
 178         put_fs_context(fc);
 179         return mnt;
 180 }
 181
 182 /*
 183  * handle an automount point
 184  */
 185 struct vfsmount *afs_d_automount(struct path *path)
 186 {
 187         struct vfsmount *newmnt;
 188
 189         _enter("{%pd}", path->dentry);
 190
 191         newmnt = afs_mntpt_do_automount(path->dentry);
 192         if (IS_ERR(newmnt))
 193                 return newmnt;
 194
 195         mntget(newmnt); /* prevent immediate expiration */
 196         mnt_set_expiry(newmnt, &afs_vfsmounts);
 197         queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
 198                            afs_mntpt_expiry_timeout * HZ);
 199         _leave(" = %p", newmnt);
 200         return newmnt;
 201 }
 202
 203 /*
 204  * handle mountpoint expiry timer going off
 205  */
 206 static void afs_mntpt_expiry_timed_out(struct work_struct *work)
 207 {
 208         _enter("");
 209
 210         if (!list_empty(&afs_vfsmounts)) {
 211                 mark_mounts_for_expiry(&afs_vfsmounts);
 212                 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
 213                                    afs_mntpt_expiry_timeout * HZ);
 214         }
 215
 216         _leave("");
 217 }
 218
 219 /*
 220  * kill the AFS mountpoint timer if it's still running
 221  */
 222 void afs_mntpt_kill_timer(void)
 223 {
 224         _enter("");
 225
 226         ASSERT(list_empty(&afs_vfsmounts));
 227         cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
 228 }