fs/ext2/namei.c

   1 /*
   2  * linux/fs/ext2/namei.c
   3  *
   4  * Rewrite to pagecache. Almost all code had been changed, so blame me
   5  * if the things go wrong. Please, send bug reports to
   6  * viro@parcelfarce.linux.theplanet.co.uk
   7  *
   8  * Stuff here is basically a glue between the VFS and generic UNIXish
   9  * filesystem that keeps everything in pagecache. All knowledge of the
  10  * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
  11  * and it's easier to debug that way. In principle we might want to
  12  * generalize that a bit and turn it into a library. Or not.
  13  *
  14  * The only non-static object here is ext2_dir_inode_operations.
  15  *
  16  * TODO: get rid of kmap() use, add readahead.
  17  *
  18  * Copyright (C) 1992, 1993, 1994, 1995
  19  * Remy Card (card@masi.ibp.fr)
  20  * Laboratoire MASI - Institut Blaise Pascal
  21  * Universite Pierre et Marie Curie (Paris VI)
  22  *
  23  *  from
  24  *
  25  *  linux/fs/minix/namei.c
  26  *
  27  *  Copyright (C) 1991, 1992  Linus Torvalds
  28  *
  29  *  Big-endian to little-endian byte-swapping/bitmaps by
  30  *        David S. Miller (davem@caip.rutgers.edu), 1995
  31  */
  32
  33 #include <linux/pagemap.h>
  34 #include "ext2.h"
  35 #include "xattr.h"
  36 #include "acl.h"
  37 #include "xip.h"
  38
  39 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  40 {
  41         int err = ext2_add_link(dentry, inode);
  42         if (!err) {
  43                 d_instantiate(dentry, inode);
  44                 unlock_new_inode(inode);
  45                 return 0;
  46         }
  47         inode_dec_link_count(inode);
  48         unlock_new_inode(inode);
  49         iput(inode);
  50         return err;
  51 }
  52
  53 /*
  54  * Methods themselves.
  55  */
  56
  57 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  58 {
  59         struct inode * inode;
  60         ino_t ino;
  61
  62         if (dentry->d_name.len > EXT2_NAME_LEN)
  63                 return ERR_PTR(-ENAMETOOLONG);
  64
  65         ino = ext2_inode_by_name(dir, &dentry->d_name);
  66         inode = NULL;
  67         if (ino) {
  68                 inode = ext2_iget(dir->i_sb, ino);
  69                 if (unlikely(IS_ERR(inode))) {
  70                         if (PTR_ERR(inode) == -ESTALE) {
  71                                 ext2_error(dir->i_sb, __func__,
  72                                                 "deleted inode referenced: %lu",
  73                                                 ino);
  74                                 return ERR_PTR(-EIO);
  75                         } else {
  76                                 return ERR_CAST(inode);
  77                         }
  78                 }
  79         }
  80         return d_splice_alias(inode, dentry);
  81 }
  82
  83 struct dentry *ext2_get_parent(struct dentry *child)
  84 {
  85         struct qstr dotdot = {.name = "..", .len = 2};
  86         unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
  87         if (!ino)
  88                 return ERR_PTR(-ENOENT);
  89         return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
  90 }
  91
  92 /*
  93  * By the time this is called, we already have created
  94  * the directory cache entry for the new file, but it
  95  * is so far negative - it has no inode.
  96  *
  97  * If the create succeeds, we fill in the inode information
  98  * with d_instantiate().
  99  */
 100 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
 101 {
 102         struct inode * inode = ext2_new_inode (dir, mode);
 103         int err = PTR_ERR(inode);
 104         if (!IS_ERR(inode)) {
 105                 inode->i_op = &ext2_file_inode_operations;
 106                 if (ext2_use_xip(inode->i_sb)) {
 107                         inode->i_mapping->a_ops = &ext2_aops_xip;
 108                         inode->i_fop = &ext2_xip_file_operations;
 109                 } else if (test_opt(inode->i_sb, NOBH)) {
 110                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 111                         inode->i_fop = &ext2_file_operations;
 112                 } else {
 113                         inode->i_mapping->a_ops = &ext2_aops;
 114                         inode->i_fop = &ext2_file_operations;
 115                 }
 116                 mark_inode_dirty(inode);
 117                 err = ext2_add_nondir(dentry, inode);
 118         }
 119         return err;
 120 }
 121
 122 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 123 {
 124         struct inode * inode;
 125         int err;
 126
 127         if (!new_valid_dev(rdev))
 128                 return -EINVAL;
 129
 130         inode = ext2_new_inode (dir, mode);
 131         err = PTR_ERR(inode);
 132         if (!IS_ERR(inode)) {
 133                 init_special_inode(inode, inode->i_mode, rdev);
 134 #ifdef CONFIG_EXT2_FS_XATTR
 135                 inode->i_op = &ext2_special_inode_operations;
 136 #endif
 137                 mark_inode_dirty(inode);
 138                 err = ext2_add_nondir(dentry, inode);
 139         }
 140         return err;
 141 }
 142
 143 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 144         const char * symname)
 145 {
 146         struct super_block * sb = dir->i_sb;
 147         int err = -ENAMETOOLONG;
 148         unsigned l = strlen(symname)+1;
 149         struct inode * inode;
 150
 151         if (l > sb->s_blocksize)
 152                 goto out;
 153
 154         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 155         err = PTR_ERR(inode);
 156         if (IS_ERR(inode))
 157                 goto out;
 158
 159         if (l > sizeof (EXT2_I(inode)->i_data)) {
 160                 /* slow symlink */
 161                 inode->i_op = &ext2_symlink_inode_operations;
 162                 if (test_opt(inode->i_sb, NOBH))
 163                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 164                 else
 165                         inode->i_mapping->a_ops = &ext2_aops;
 166                 err = page_symlink(inode, symname, l);
 167                 if (err)
 168                         goto out_fail;
 169         } else {
 170                 /* fast symlink */
 171                 inode->i_op = &ext2_fast_symlink_inode_operations;
 172                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 173                 inode->i_size = l-1;
 174         }
 175         mark_inode_dirty(inode);
 176
 177         err = ext2_add_nondir(dentry, inode);
 178 out:
 179         return err;
 180
 181 out_fail:
 182         inode_dec_link_count(inode);
 183         unlock_new_inode(inode);
 184         iput (inode);
 185         goto out;
 186 }
 187
 188 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 189         struct dentry *dentry)
 190 {
 191         struct inode *inode = old_dentry->d_inode;
 192         int err;
 193
 194         if (inode->i_nlink >= EXT2_LINK_MAX)
 195                 return -EMLINK;
 196
 197         inode->i_ctime = CURRENT_TIME_SEC;
 198         inode_inc_link_count(inode);
 199         atomic_inc(&inode->i_count);
 200
 201         err = ext2_add_link(dentry, inode);
 202         if (!err) {
 203                 d_instantiate(dentry, inode);
 204                 return 0;
 205         }
 206         inode_dec_link_count(inode);
 207         iput(inode);
 208         return err;
 209 }
 210
 211 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 212 {
 213         struct inode * inode;
 214         int err = -EMLINK;
 215
 216         if (dir->i_nlink >= EXT2_LINK_MAX)
 217                 goto out;
 218
 219         inode_inc_link_count(dir);
 220
 221         inode = ext2_new_inode (dir, S_IFDIR | mode);
 222         err = PTR_ERR(inode);
 223         if (IS_ERR(inode))
 224                 goto out_dir;
 225
 226         inode->i_op = &ext2_dir_inode_operations;
 227         inode->i_fop = &ext2_dir_operations;
 228         if (test_opt(inode->i_sb, NOBH))
 229                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 230         else
 231                 inode->i_mapping->a_ops = &ext2_aops;
 232
 233         inode_inc_link_count(inode);
 234
 235         err = ext2_make_empty(inode, dir);
 236         if (err)
 237                 goto out_fail;
 238
 239         err = ext2_add_link(dentry, inode);
 240         if (err)
 241                 goto out_fail;
 242
 243         d_instantiate(dentry, inode);
 244         unlock_new_inode(inode);
 245 out:
 246         return err;
 247
 248 out_fail:
 249         inode_dec_link_count(inode);
 250         inode_dec_link_count(inode);
 251         unlock_new_inode(inode);
 252         iput(inode);
 253 out_dir:
 254         inode_dec_link_count(dir);
 255         goto out;
 256 }
 257
 258 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 259 {
 260         struct inode * inode = dentry->d_inode;
 261         struct ext2_dir_entry_2 * de;
 262         struct page * page;
 263         int err = -ENOENT;
 264
 265         de = ext2_find_entry (dir, &dentry->d_name, &page);
 266         if (!de)
 267                 goto out;
 268
 269         err = ext2_delete_entry (de, page);
 270         if (err)
 271                 goto out;
 272
 273         inode->i_ctime = dir->i_ctime;
 274         inode_dec_link_count(inode);
 275         err = 0;
 276 out:
 277         return err;
 278 }
 279
 280 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 281 {
 282         struct inode * inode = dentry->d_inode;
 283         int err = -ENOTEMPTY;
 284
 285         if (ext2_empty_dir(inode)) {
 286                 err = ext2_unlink(dir, dentry);
 287                 if (!err) {
 288                         inode->i_size = 0;
 289                         inode_dec_link_count(inode);
 290                         inode_dec_link_count(dir);
 291                 }
 292         }
 293         return err;
 294 }
 295
 296 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 297         struct inode * new_dir, struct dentry * new_dentry )
 298 {
 299         struct inode * old_inode = old_dentry->d_inode;
 300         struct inode * new_inode = new_dentry->d_inode;
 301         struct page * dir_page = NULL;
 302         struct ext2_dir_entry_2 * dir_de = NULL;
 303         struct page * old_page;
 304         struct ext2_dir_entry_2 * old_de;
 305         int err = -ENOENT;
 306
 307         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 308         if (!old_de)
 309                 goto out;
 310
 311         if (S_ISDIR(old_inode->i_mode)) {
 312                 err = -EIO;
 313                 dir_de = ext2_dotdot(old_inode, &dir_page);
 314                 if (!dir_de)
 315                         goto out_old;
 316         }
 317
 318         if (new_inode) {
 319                 struct page *new_page;
 320                 struct ext2_dir_entry_2 *new_de;
 321
 322                 err = -ENOTEMPTY;
 323                 if (dir_de && !ext2_empty_dir (new_inode))
 324                         goto out_dir;
 325
 326                 err = -ENOENT;
 327                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 328                 if (!new_de)
 329                         goto out_dir;
 330                 inode_inc_link_count(old_inode);
 331                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 332                 new_inode->i_ctime = CURRENT_TIME_SEC;
 333                 if (dir_de)
 334                         drop_nlink(new_inode);
 335                 inode_dec_link_count(new_inode);
 336         } else {
 337                 if (dir_de) {
 338                         err = -EMLINK;
 339                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 340                                 goto out_dir;
 341                 }
 342                 inode_inc_link_count(old_inode);
 343                 err = ext2_add_link(new_dentry, old_inode);
 344                 if (err) {
 345                         inode_dec_link_count(old_inode);
 346                         goto out_dir;
 347                 }
 348                 if (dir_de)
 349                         inode_inc_link_count(new_dir);
 350         }
 351
 352         /*
 353          * Like most other Unix systems, set the ctime for inodes on a
 354          * rename.
 355          * inode_dec_link_count() will mark the inode dirty.
 356          */
 357         old_inode->i_ctime = CURRENT_TIME_SEC;
 358
 359         ext2_delete_entry (old_de, old_page);
 360         inode_dec_link_count(old_inode);
 361
 362         if (dir_de) {
 363                 if (old_dir != new_dir)
 364                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 365                 inode_dec_link_count(old_dir);
 366         }
 367         return 0;
 368
 369
 370 out_dir:
 371         if (dir_de) {
 372                 kunmap(dir_page);
 373                 page_cache_release(dir_page);
 374         }
 375 out_old:
 376         kunmap(old_page);
 377         page_cache_release(old_page);
 378 out:
 379         return err;
 380 }
 381
 382 const struct inode_operations ext2_dir_inode_operations = {
 383         .create         = ext2_create,
 384         .lookup         = ext2_lookup,
 385         .link           = ext2_link,
 386         .unlink         = ext2_unlink,
 387         .symlink        = ext2_symlink,
 388         .mkdir          = ext2_mkdir,
 389         .rmdir          = ext2_rmdir,
 390         .mknod          = ext2_mknod,
 391         .rename         = ext2_rename,
 392 #ifdef CONFIG_EXT2_FS_XATTR
 393         .setxattr       = generic_setxattr,
 394         .getxattr       = generic_getxattr,
 395         .listxattr      = ext2_listxattr,
 396         .removexattr    = generic_removexattr,
 397 #endif
 398         .setattr        = ext2_setattr,
 399         .permission     = ext2_permission,
 400 };
 401
 402 const struct inode_operations ext2_special_inode_operations = {
 403 #ifdef CONFIG_EXT2_FS_XATTR
 404         .setxattr       = generic_setxattr,
 405         .getxattr       = generic_getxattr,
 406         .listxattr      = ext2_listxattr,
 407         .removexattr    = generic_removexattr,
 408 #endif
 409         .setattr        = ext2_setattr,
 410         .permission     = ext2_permission,
 411 };