Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) Neil Brown 2002 |
| 3 | * Copyright (C) Christoph Hellwig 2007 |
| 4 | * |
| 5 | * This file contains the code mapping from inodes to NFS file handles, |
| 6 | * and for mapping back from file handles to dentries. |
| 7 | * |
| 8 | * For details on why we do all the strange and hairy things in here |
J. Bruce Fields | dc7a081 | 2009-10-27 14:41:35 -0400 | [diff] [blame] | 9 | * take a look at Documentation/filesystems/nfs/Exporting. |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 10 | */ |
Christoph Hellwig | a569425 | 2007-07-17 04:04:28 -0700 | [diff] [blame] | 11 | #include <linux/exportfs.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 12 | #include <linux/fs.h> |
| 13 | #include <linux/file.h> |
| 14 | #include <linux/module.h> |
Christoph Hellwig | d37065c | 2007-07-17 04:04:30 -0700 | [diff] [blame] | 15 | #include <linux/mount.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/namei.h> |
David Howells | 745ca24 | 2008-11-14 10:39:22 +1100 | [diff] [blame] | 17 | #include <linux/sched.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 19 | #define dprintk(fmt, args...) do{}while(0) |
| 20 | |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 21 | |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 22 | static int get_name(struct vfsmount *mnt, struct dentry *dentry, char *name, |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 23 | struct dentry *child); |
| 24 | |
| 25 | |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 26 | static int exportfs_get_name(struct vfsmount *mnt, struct dentry *dir, |
| 27 | char *name, struct dentry *child) |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 28 | { |
Christoph Hellwig | 3965516 | 2007-10-21 16:42:17 -0700 | [diff] [blame] | 29 | const struct export_operations *nop = dir->d_sb->s_export_op; |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 30 | |
| 31 | if (nop->get_name) |
| 32 | return nop->get_name(dir, name, child); |
| 33 | else |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 34 | return get_name(mnt, dir, name, child); |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 35 | } |
| 36 | |
Christoph Hellwig | fb66a19 | 2007-07-17 04:04:32 -0700 | [diff] [blame] | 37 | /* |
| 38 | * Check if the dentry or any of it's aliases is acceptable. |
| 39 | */ |
Christoph Hellwig | e2f9901 | 2006-01-18 17:43:52 -0800 | [diff] [blame] | 40 | static struct dentry * |
| 41 | find_acceptable_alias(struct dentry *result, |
| 42 | int (*acceptable)(void *context, struct dentry *dentry), |
| 43 | void *context) |
| 44 | { |
| 45 | struct dentry *dentry, *toput = NULL; |
| 46 | |
Christoph Hellwig | fb66a19 | 2007-07-17 04:04:32 -0700 | [diff] [blame] | 47 | if (acceptable(context, result)) |
| 48 | return result; |
| 49 | |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 50 | spin_lock(&dcache_inode_lock); |
Christoph Hellwig | e2f9901 | 2006-01-18 17:43:52 -0800 | [diff] [blame] | 51 | list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) { |
Nick Piggin | dc0474b | 2011-01-07 17:49:43 +1100 | [diff] [blame] | 52 | dget(dentry); |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 53 | spin_unlock(&dcache_inode_lock); |
Christoph Hellwig | e2f9901 | 2006-01-18 17:43:52 -0800 | [diff] [blame] | 54 | if (toput) |
| 55 | dput(toput); |
| 56 | if (dentry != result && acceptable(context, dentry)) { |
| 57 | dput(result); |
| 58 | return dentry; |
| 59 | } |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 60 | spin_lock(&dcache_inode_lock); |
Christoph Hellwig | e2f9901 | 2006-01-18 17:43:52 -0800 | [diff] [blame] | 61 | toput = dentry; |
| 62 | } |
Nick Piggin | b23fb0a | 2011-01-07 17:49:35 +1100 | [diff] [blame] | 63 | spin_unlock(&dcache_inode_lock); |
Christoph Hellwig | e2f9901 | 2006-01-18 17:43:52 -0800 | [diff] [blame] | 64 | |
| 65 | if (toput) |
| 66 | dput(toput); |
| 67 | return NULL; |
| 68 | } |
| 69 | |
Christoph Hellwig | dd90b50 | 2007-07-17 04:04:32 -0700 | [diff] [blame] | 70 | /* |
| 71 | * Find root of a disconnected subtree and return a reference to it. |
| 72 | */ |
| 73 | static struct dentry * |
| 74 | find_disconnected_root(struct dentry *dentry) |
| 75 | { |
| 76 | dget(dentry); |
Christoph Hellwig | 0461ee2 | 2010-10-13 11:56:37 -0400 | [diff] [blame] | 77 | while (!IS_ROOT(dentry)) { |
| 78 | struct dentry *parent = dget_parent(dentry); |
| 79 | |
| 80 | if (!(parent->d_flags & DCACHE_DISCONNECTED)) { |
| 81 | dput(parent); |
| 82 | break; |
| 83 | } |
| 84 | |
Christoph Hellwig | dd90b50 | 2007-07-17 04:04:32 -0700 | [diff] [blame] | 85 | dput(dentry); |
| 86 | dentry = parent; |
Christoph Hellwig | dd90b50 | 2007-07-17 04:04:32 -0700 | [diff] [blame] | 87 | } |
Christoph Hellwig | dd90b50 | 2007-07-17 04:04:32 -0700 | [diff] [blame] | 88 | return dentry; |
| 89 | } |
| 90 | |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 91 | /* |
| 92 | * Make sure target_dir is fully connected to the dentry tree. |
| 93 | * |
| 94 | * It may already be, as the flag isn't always updated when connection happens. |
| 95 | */ |
| 96 | static int |
Al Viro | f3f8e17 | 2008-08-11 12:39:47 -0400 | [diff] [blame] | 97 | reconnect_path(struct vfsmount *mnt, struct dentry *target_dir, char *nbuf) |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 98 | { |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 99 | int noprogress = 0; |
| 100 | int err = -ESTALE; |
| 101 | |
| 102 | /* |
| 103 | * It is possible that a confused file system might not let us complete |
| 104 | * the path to the root. For example, if get_parent returns a directory |
| 105 | * in which we cannot find a name for the child. While this implies a |
| 106 | * very sick filesystem we don't want it to cause knfsd to spin. Hence |
| 107 | * the noprogress counter. If we go through the loop 10 times (2 is |
| 108 | * probably enough) without getting anywhere, we just give up |
| 109 | */ |
| 110 | while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) { |
| 111 | struct dentry *pd = find_disconnected_root(target_dir); |
| 112 | |
| 113 | if (!IS_ROOT(pd)) { |
| 114 | /* must have found a connected parent - great */ |
| 115 | spin_lock(&pd->d_lock); |
| 116 | pd->d_flags &= ~DCACHE_DISCONNECTED; |
| 117 | spin_unlock(&pd->d_lock); |
| 118 | noprogress = 0; |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 119 | } else if (pd == mnt->mnt_sb->s_root) { |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 120 | printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n"); |
| 121 | spin_lock(&pd->d_lock); |
| 122 | pd->d_flags &= ~DCACHE_DISCONNECTED; |
| 123 | spin_unlock(&pd->d_lock); |
| 124 | noprogress = 0; |
| 125 | } else { |
| 126 | /* |
| 127 | * We have hit the top of a disconnected path, try to |
| 128 | * find parent and connect. |
| 129 | * |
| 130 | * Racing with some other process renaming a directory |
| 131 | * isn't much of a problem here. If someone renames |
| 132 | * the directory, it will end up properly connected, |
| 133 | * which is what we want |
| 134 | * |
| 135 | * Getting the parent can't be supported generically, |
| 136 | * the locking is too icky. |
| 137 | * |
| 138 | * Instead we just return EACCES. If server reboots |
| 139 | * or inodes get flushed, you lose |
| 140 | */ |
| 141 | struct dentry *ppd = ERR_PTR(-EACCES); |
| 142 | struct dentry *npd; |
| 143 | |
| 144 | mutex_lock(&pd->d_inode->i_mutex); |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 145 | if (mnt->mnt_sb->s_export_op->get_parent) |
| 146 | ppd = mnt->mnt_sb->s_export_op->get_parent(pd); |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 147 | mutex_unlock(&pd->d_inode->i_mutex); |
| 148 | |
| 149 | if (IS_ERR(ppd)) { |
| 150 | err = PTR_ERR(ppd); |
| 151 | dprintk("%s: get_parent of %ld failed, err %d\n", |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 152 | __func__, pd->d_inode->i_ino, err); |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 153 | dput(pd); |
| 154 | break; |
| 155 | } |
| 156 | |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 157 | dprintk("%s: find name of %lu in %lu\n", __func__, |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 158 | pd->d_inode->i_ino, ppd->d_inode->i_ino); |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 159 | err = exportfs_get_name(mnt, ppd, nbuf, pd); |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 160 | if (err) { |
| 161 | dput(ppd); |
| 162 | dput(pd); |
| 163 | if (err == -ENOENT) |
| 164 | /* some race between get_parent and |
| 165 | * get_name? just try again |
| 166 | */ |
| 167 | continue; |
| 168 | break; |
| 169 | } |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 170 | dprintk("%s: found name: %s\n", __func__, nbuf); |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 171 | mutex_lock(&ppd->d_inode->i_mutex); |
| 172 | npd = lookup_one_len(nbuf, ppd, strlen(nbuf)); |
| 173 | mutex_unlock(&ppd->d_inode->i_mutex); |
| 174 | if (IS_ERR(npd)) { |
| 175 | err = PTR_ERR(npd); |
| 176 | dprintk("%s: lookup failed: %d\n", |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 177 | __func__, err); |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 178 | dput(ppd); |
| 179 | dput(pd); |
| 180 | break; |
| 181 | } |
| 182 | /* we didn't really want npd, we really wanted |
| 183 | * a side-effect of the lookup. |
| 184 | * hopefully, npd == pd, though it isn't really |
| 185 | * a problem if it isn't |
| 186 | */ |
| 187 | if (npd == pd) |
| 188 | noprogress = 0; |
| 189 | else |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 190 | printk("%s: npd != pd\n", __func__); |
Christoph Hellwig | 019ab80 | 2007-07-17 04:04:33 -0700 | [diff] [blame] | 191 | dput(npd); |
| 192 | dput(ppd); |
| 193 | if (IS_ROOT(pd)) { |
| 194 | /* something went wrong, we have to give up */ |
| 195 | dput(pd); |
| 196 | break; |
| 197 | } |
| 198 | } |
| 199 | dput(pd); |
| 200 | } |
| 201 | |
| 202 | if (target_dir->d_flags & DCACHE_DISCONNECTED) { |
| 203 | /* something went wrong - oh-well */ |
| 204 | if (!err) |
| 205 | err = -ESTALE; |
| 206 | return err; |
| 207 | } |
| 208 | |
| 209 | return 0; |
| 210 | } |
| 211 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 212 | struct getdents_callback { |
| 213 | char *name; /* name that was found. It already points to a |
| 214 | buffer NAME_MAX+1 is size */ |
| 215 | unsigned long ino; /* the inum we are looking for */ |
| 216 | int found; /* inode matched? */ |
| 217 | int sequence; /* sequence counter */ |
| 218 | }; |
| 219 | |
| 220 | /* |
| 221 | * A rather strange filldir function to capture |
| 222 | * the name matching the specified inode number. |
| 223 | */ |
| 224 | static int filldir_one(void * __buf, const char * name, int len, |
David Howells | afefdbb | 2006-10-03 01:13:46 -0700 | [diff] [blame] | 225 | loff_t pos, u64 ino, unsigned int d_type) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | { |
| 227 | struct getdents_callback *buf = __buf; |
| 228 | int result = 0; |
| 229 | |
| 230 | buf->sequence++; |
| 231 | if (buf->ino == ino) { |
| 232 | memcpy(buf->name, name, len); |
| 233 | buf->name[len] = '\0'; |
| 234 | buf->found = 1; |
| 235 | result = -1; |
| 236 | } |
| 237 | return result; |
| 238 | } |
| 239 | |
| 240 | /** |
| 241 | * get_name - default export_operations->get_name function |
| 242 | * @dentry: the directory in which to find a name |
| 243 | * @name: a pointer to a %NAME_MAX+1 char buffer to store the name |
| 244 | * @child: the dentry for the child directory. |
| 245 | * |
| 246 | * calls readdir on the parent until it finds an entry with |
| 247 | * the same inode number as the child, and returns that. |
| 248 | */ |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 249 | static int get_name(struct vfsmount *mnt, struct dentry *dentry, |
| 250 | char *name, struct dentry *child) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 251 | { |
David Howells | 745ca24 | 2008-11-14 10:39:22 +1100 | [diff] [blame] | 252 | const struct cred *cred = current_cred(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 253 | struct inode *dir = dentry->d_inode; |
| 254 | int error; |
| 255 | struct file *file; |
| 256 | struct getdents_callback buffer; |
| 257 | |
| 258 | error = -ENOTDIR; |
| 259 | if (!dir || !S_ISDIR(dir->i_mode)) |
| 260 | goto out; |
| 261 | error = -EINVAL; |
| 262 | if (!dir->i_fop) |
| 263 | goto out; |
| 264 | /* |
| 265 | * Open the directory ... |
| 266 | */ |
David Howells | 745ca24 | 2008-11-14 10:39:22 +1100 | [diff] [blame] | 267 | file = dentry_open(dget(dentry), mntget(mnt), O_RDONLY, cred); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 268 | error = PTR_ERR(file); |
| 269 | if (IS_ERR(file)) |
| 270 | goto out; |
| 271 | |
| 272 | error = -EINVAL; |
| 273 | if (!file->f_op->readdir) |
| 274 | goto out_close; |
| 275 | |
| 276 | buffer.name = name; |
| 277 | buffer.ino = child->d_inode->i_ino; |
| 278 | buffer.found = 0; |
| 279 | buffer.sequence = 0; |
| 280 | while (1) { |
| 281 | int old_seq = buffer.sequence; |
| 282 | |
| 283 | error = vfs_readdir(file, filldir_one, &buffer); |
Al Viro | 53c9c5c | 2008-08-24 07:29:52 -0400 | [diff] [blame] | 284 | if (buffer.found) { |
| 285 | error = 0; |
| 286 | break; |
| 287 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 288 | |
| 289 | if (error < 0) |
| 290 | break; |
| 291 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 292 | error = -ENOENT; |
| 293 | if (old_seq == buffer.sequence) |
| 294 | break; |
| 295 | } |
| 296 | |
| 297 | out_close: |
| 298 | fput(file); |
| 299 | out: |
| 300 | return error; |
| 301 | } |
| 302 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 303 | /** |
| 304 | * export_encode_fh - default export_operations->encode_fh function |
| 305 | * @dentry: the dentry to encode |
| 306 | * @fh: where to store the file handle fragment |
| 307 | * @max_len: maximum length to store there |
| 308 | * @connectable: whether to store parent information |
| 309 | * |
| 310 | * This default encode_fh function assumes that the 32 inode number |
| 311 | * is suitable for locating an inode, and that the generation number |
| 312 | * can be used to check that it is still valid. It places them in the |
| 313 | * filehandle fragment where export_decode_fh expects to find them. |
| 314 | */ |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 315 | static int export_encode_fh(struct dentry *dentry, struct fid *fid, |
| 316 | int *max_len, int connectable) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 317 | { |
| 318 | struct inode * inode = dentry->d_inode; |
| 319 | int len = *max_len; |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 320 | int type = FILEID_INO32_GEN; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 321 | |
| 322 | if (len < 2 || (connectable && len < 4)) |
| 323 | return 255; |
| 324 | |
| 325 | len = 2; |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 326 | fid->i32.ino = inode->i_ino; |
| 327 | fid->i32.gen = inode->i_generation; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 328 | if (connectable && !S_ISDIR(inode->i_mode)) { |
| 329 | struct inode *parent; |
| 330 | |
| 331 | spin_lock(&dentry->d_lock); |
| 332 | parent = dentry->d_parent->d_inode; |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 333 | fid->i32.parent_ino = parent->i_ino; |
| 334 | fid->i32.parent_gen = parent->i_generation; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 335 | spin_unlock(&dentry->d_lock); |
| 336 | len = 4; |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 337 | type = FILEID_INO32_GEN_PARENT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 338 | } |
| 339 | *max_len = len; |
| 340 | return type; |
| 341 | } |
| 342 | |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 343 | int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len, |
Christoph Hellwig | d37065c | 2007-07-17 04:04:30 -0700 | [diff] [blame] | 344 | int connectable) |
| 345 | { |
Christoph Hellwig | 3965516 | 2007-10-21 16:42:17 -0700 | [diff] [blame] | 346 | const struct export_operations *nop = dentry->d_sb->s_export_op; |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 347 | int error; |
Christoph Hellwig | d37065c | 2007-07-17 04:04:30 -0700 | [diff] [blame] | 348 | |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 349 | if (nop->encode_fh) |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 350 | error = nop->encode_fh(dentry, fid->raw, max_len, connectable); |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 351 | else |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 352 | error = export_encode_fh(dentry, fid, max_len, connectable); |
Christoph Hellwig | 10f11c3 | 2007-07-17 04:04:31 -0700 | [diff] [blame] | 353 | |
| 354 | return error; |
Christoph Hellwig | d37065c | 2007-07-17 04:04:30 -0700 | [diff] [blame] | 355 | } |
| 356 | EXPORT_SYMBOL_GPL(exportfs_encode_fh); |
| 357 | |
Christoph Hellwig | 6e91ea2 | 2007-10-21 16:42:03 -0700 | [diff] [blame] | 358 | struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid, |
| 359 | int fh_len, int fileid_type, |
| 360 | int (*acceptable)(void *, struct dentry *), void *context) |
Christoph Hellwig | d37065c | 2007-07-17 04:04:30 -0700 | [diff] [blame] | 361 | { |
Christoph Hellwig | 3965516 | 2007-10-21 16:42:17 -0700 | [diff] [blame] | 362 | const struct export_operations *nop = mnt->mnt_sb->s_export_op; |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 363 | struct dentry *result, *alias; |
Al Viro | f3f8e17 | 2008-08-11 12:39:47 -0400 | [diff] [blame] | 364 | char nbuf[NAME_MAX+1]; |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 365 | int err; |
Christoph Hellwig | d37065c | 2007-07-17 04:04:30 -0700 | [diff] [blame] | 366 | |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 367 | /* |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 368 | * Try to get any dentry for the given file handle from the filesystem. |
| 369 | */ |
| 370 | result = nop->fh_to_dentry(mnt->mnt_sb, fid, fh_len, fileid_type); |
J. Bruce Fields | a4f4d6d | 2008-12-08 18:24:18 -0500 | [diff] [blame] | 371 | if (!result) |
| 372 | result = ERR_PTR(-ESTALE); |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 373 | if (IS_ERR(result)) |
| 374 | return result; |
| 375 | |
| 376 | if (S_ISDIR(result->d_inode->i_mode)) { |
| 377 | /* |
| 378 | * This request is for a directory. |
| 379 | * |
| 380 | * On the positive side there is only one dentry for each |
| 381 | * directory inode. On the negative side this implies that we |
| 382 | * to ensure our dentry is connected all the way up to the |
| 383 | * filesystem root. |
| 384 | */ |
| 385 | if (result->d_flags & DCACHE_DISCONNECTED) { |
Al Viro | f3f8e17 | 2008-08-11 12:39:47 -0400 | [diff] [blame] | 386 | err = reconnect_path(mnt, result, nbuf); |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 387 | if (err) |
| 388 | goto err_result; |
| 389 | } |
| 390 | |
| 391 | if (!acceptable(context, result)) { |
| 392 | err = -EACCES; |
| 393 | goto err_result; |
| 394 | } |
| 395 | |
| 396 | return result; |
| 397 | } else { |
| 398 | /* |
| 399 | * It's not a directory. Life is a little more complicated. |
| 400 | */ |
| 401 | struct dentry *target_dir, *nresult; |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 402 | |
| 403 | /* |
| 404 | * See if either the dentry we just got from the filesystem |
| 405 | * or any alias for it is acceptable. This is always true |
| 406 | * if this filesystem is exported without the subtreecheck |
| 407 | * option. If the filesystem is exported with the subtree |
| 408 | * check option there's a fair chance we need to look at |
| 409 | * the parent directory in the file handle and make sure |
| 410 | * it's connected to the filesystem root. |
| 411 | */ |
| 412 | alias = find_acceptable_alias(result, acceptable, context); |
| 413 | if (alias) |
| 414 | return alias; |
| 415 | |
| 416 | /* |
| 417 | * Try to extract a dentry for the parent directory from the |
| 418 | * file handle. If this fails we'll have to give up. |
| 419 | */ |
| 420 | err = -ESTALE; |
| 421 | if (!nop->fh_to_parent) |
| 422 | goto err_result; |
| 423 | |
| 424 | target_dir = nop->fh_to_parent(mnt->mnt_sb, fid, |
| 425 | fh_len, fileid_type); |
J. Bruce Fields | a4f4d6d | 2008-12-08 18:24:18 -0500 | [diff] [blame] | 426 | if (!target_dir) |
| 427 | goto err_result; |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 428 | err = PTR_ERR(target_dir); |
| 429 | if (IS_ERR(target_dir)) |
| 430 | goto err_result; |
| 431 | |
| 432 | /* |
| 433 | * And as usual we need to make sure the parent directory is |
| 434 | * connected to the filesystem root. The VFS really doesn't |
| 435 | * like disconnected directories.. |
| 436 | */ |
Al Viro | f3f8e17 | 2008-08-11 12:39:47 -0400 | [diff] [blame] | 437 | err = reconnect_path(mnt, target_dir, nbuf); |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 438 | if (err) { |
| 439 | dput(target_dir); |
| 440 | goto err_result; |
| 441 | } |
| 442 | |
| 443 | /* |
| 444 | * Now that we've got both a well-connected parent and a |
| 445 | * dentry for the inode we're after, make sure that our |
| 446 | * inode is actually connected to the parent. |
| 447 | */ |
Christoph Hellwig | e38f981 | 2007-10-21 16:42:19 -0700 | [diff] [blame] | 448 | err = exportfs_get_name(mnt, target_dir, nbuf, result); |
Christoph Hellwig | 2596110 | 2007-10-21 16:42:05 -0700 | [diff] [blame] | 449 | if (!err) { |
| 450 | mutex_lock(&target_dir->d_inode->i_mutex); |
| 451 | nresult = lookup_one_len(nbuf, target_dir, |
| 452 | strlen(nbuf)); |
| 453 | mutex_unlock(&target_dir->d_inode->i_mutex); |
| 454 | if (!IS_ERR(nresult)) { |
| 455 | if (nresult->d_inode) { |
| 456 | dput(result); |
| 457 | result = nresult; |
| 458 | } else |
| 459 | dput(nresult); |
| 460 | } |
| 461 | } |
| 462 | |
| 463 | /* |
| 464 | * At this point we are done with the parent, but it's pinned |
| 465 | * by the child dentry anyway. |
| 466 | */ |
| 467 | dput(target_dir); |
| 468 | |
| 469 | /* |
| 470 | * And finally make sure the dentry is actually acceptable |
| 471 | * to NFSD. |
| 472 | */ |
| 473 | alias = find_acceptable_alias(result, acceptable, context); |
| 474 | if (!alias) { |
| 475 | err = -EACCES; |
| 476 | goto err_result; |
| 477 | } |
| 478 | |
| 479 | return alias; |
| 480 | } |
| 481 | |
| 482 | err_result: |
| 483 | dput(result); |
| 484 | return ERR_PTR(err); |
Christoph Hellwig | d37065c | 2007-07-17 04:04:30 -0700 | [diff] [blame] | 485 | } |
| 486 | EXPORT_SYMBOL_GPL(exportfs_decode_fh); |
| 487 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 488 | MODULE_LICENSE("GPL"); |