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 } 229