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 <linux/quotaops.h>
  35 #include "ext2.h"
  36 #include "xattr.h"
  37 #include "acl.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                 unlock_new_inode(inode);
  44                 d_instantiate(dentry, 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, unsigned int flags)
  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 (inode == ERR_PTR(-ESTALE)) {
  70                         ext2_error(dir->i_sb, __func__,
  71                                         "deleted inode referenced: %lu",
  72                                         (unsigned long) ino);
  73                         return ERR_PTR(-EIO);
  74                 }
  75         }
  76         return d_splice_alias(inode, dentry);
  77 }
  78
  79 struct dentry *ext2_get_parent(struct dentry *child)
  80 {
  81         struct qstr dotdot = QSTR_INIT("..", 2);
  82         unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
  83         if (!ino)
  84                 return ERR_PTR(-ENOENT);
  85         return d_obtain_alias(ext2_iget(d_inode(child)->i_sb, ino));
  86 }
  87
  88 /*
  89  * By the time this is called, we already have created
  90  * the directory cache entry for the new file, but it
  91  * is so far negative - it has no inode.
  92  *
  93  * If the create succeeds, we fill in the inode information
  94  * with d_instantiate().
  95  */
  96 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
  97 {
  98         struct inode *inode;
  99         int err;
 100
 101         err = dquot_initialize(dir);
 102         if (err)
 103                 return err;
 104
 105         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 106         if (IS_ERR(inode))
 107                 return PTR_ERR(inode);
 108
 109         inode->i_op = &ext2_file_inode_operations;
 110         if (test_opt(inode->i_sb, NOBH)) {
 111                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 112                 inode->i_fop = &ext2_file_operations;
 113         } else {
 114                 inode->i_mapping->a_ops = &ext2_aops;
 115                 inode->i_fop = &ext2_file_operations;
 116         }
 117         mark_inode_dirty(inode);
 118         return ext2_add_nondir(dentry, inode);
 119 }
 120
 121 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 122 {
 123         struct inode *inode = ext2_new_inode(dir, mode, NULL);
 124         if (IS_ERR(inode))
 125                 return PTR_ERR(inode);
 126
 127         inode->i_op = &ext2_file_inode_operations;
 128         if (test_opt(inode->i_sb, NOBH)) {
 129                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 130                 inode->i_fop = &ext2_file_operations;
 131         } else {
 132                 inode->i_mapping->a_ops = &ext2_aops;
 133                 inode->i_fop = &ext2_file_operations;
 134         }
 135         mark_inode_dirty(inode);
 136         d_tmpfile(dentry, inode);
 137         unlock_new_inode(inode);
 138         return 0;
 139 }
 140
 141 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 142 {
 143         struct inode * inode;
 144         int err;
 145
 146         if (!new_valid_dev(rdev))
 147                 return -EINVAL;
 148
 149         err = dquot_initialize(dir);
 150         if (err)
 151                 return err;
 152
 153         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 154         err = PTR_ERR(inode);
 155         if (!IS_ERR(inode)) {
 156                 init_special_inode(inode, inode->i_mode, rdev);
 157 #ifdef CONFIG_EXT2_FS_XATTR
 158                 inode->i_op = &ext2_special_inode_operations;
 159 #endif
 160                 mark_inode_dirty(inode);
 161                 err = ext2_add_nondir(dentry, inode);
 162         }
 163         return err;
 164 }
 165
 166 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 167         const char * symname)
 168 {
 169         struct super_block * sb = dir->i_sb;
 170         int err = -ENAMETOOLONG;
 171         unsigned l = strlen(symname)+1;
 172         struct inode * inode;
 173
 174         if (l > sb->s_blocksize)
 175                 goto out;
 176
 177         err = dquot_initialize(dir);
 178         if (err)
 179                 goto out;
 180
 181         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 182         err = PTR_ERR(inode);
 183         if (IS_ERR(inode))
 184                 goto out;
 185
 186         if (l > sizeof (EXT2_I(inode)->i_data)) {
 187                 /* slow symlink */
 188                 inode->i_op = &ext2_symlink_inode_operations;
 189                 if (test_opt(inode->i_sb, NOBH))
 190                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 191                 else
 192                         inode->i_mapping->a_ops = &ext2_aops;
 193                 err = page_symlink(inode, symname, l);
 194                 if (err)
 195                         goto out_fail;
 196         } else {
 197                 /* fast symlink */
 198                 inode->i_op = &ext2_fast_symlink_inode_operations;
 199                 inode->i_link = (char*)EXT2_I(inode)->i_data;
 200                 memcpy(inode->i_link, symname, l);
 201                 inode->i_size = l-1;
 202         }
 203         mark_inode_dirty(inode);
 204
 205         err = ext2_add_nondir(dentry, inode);
 206 out:
 207         return err;
 208
 209 out_fail:
 210         inode_dec_link_count(inode);
 211         unlock_new_inode(inode);
 212         iput (inode);
 213         goto out;
 214 }
 215
 216 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 217         struct dentry *dentry)
 218 {
 219         struct inode *inode = d_inode(old_dentry);
 220         int err;
 221
 222         err = dquot_initialize(dir);
 223         if (err)
 224                 return err;
 225
 226         inode->i_ctime = CURRENT_TIME_SEC;
 227         inode_inc_link_count(inode);
 228         ihold(inode);
 229
 230         err = ext2_add_link(dentry, inode);
 231         if (!err) {
 232                 d_instantiate(dentry, inode);
 233                 return 0;
 234         }
 235         inode_dec_link_count(inode);
 236         iput(inode);
 237         return err;
 238 }
 239
 240 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 241 {
 242         struct inode * inode;
 243         int err;
 244
 245         err = dquot_initialize(dir);
 246         if (err)
 247                 return err;
 248
 249         inode_inc_link_count(dir);
 250
 251         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 252         err = PTR_ERR(inode);
 253         if (IS_ERR(inode))
 254                 goto out_dir;
 255
 256         inode->i_op = &ext2_dir_inode_operations;
 257         inode->i_fop = &ext2_dir_operations;
 258         if (test_opt(inode->i_sb, NOBH))
 259                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 260         else
 261                 inode->i_mapping->a_ops = &ext2_aops;
 262
 263         inode_inc_link_count(inode);
 264
 265         err = ext2_make_empty(inode, dir);
 266         if (err)
 267                 goto out_fail;
 268
 269         err = ext2_add_link(dentry, inode);
 270         if (err)
 271                 goto out_fail;
 272
 273         unlock_new_inode(inode);
 274         d_instantiate(dentry, inode);
 275 out:
 276         return err;
 277
 278 out_fail:
 279         inode_dec_link_count(inode);
 280         inode_dec_link_count(inode);
 281         unlock_new_inode(inode);
 282         iput(inode);
 283 out_dir:
 284         inode_dec_link_count(dir);
 285         goto out;
 286 }
 287
 288 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 289 {
 290         struct inode * inode = d_inode(dentry);
 291         struct ext2_dir_entry_2 * de;
 292         struct page * page;
 293         int err;
 294
 295         err = dquot_initialize(dir);
 296         if (err)
 297                 goto out;
 298
 299         de = ext2_find_entry (dir, &dentry->d_name, &page);
 300         if (!de) {
 301                 err = -ENOENT;
 302                 goto out;
 303         }
 304
 305         err = ext2_delete_entry (de, page);
 306         if (err)
 307                 goto out;
 308
 309         inode->i_ctime = dir->i_ctime;
 310         inode_dec_link_count(inode);
 311         err = 0;
 312 out:
 313         return err;
 314 }
 315
 316 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 317 {
 318         struct inode * inode = d_inode(dentry);
 319         int err = -ENOTEMPTY;
 320
 321         if (ext2_empty_dir(inode)) {
 322                 err = ext2_unlink(dir, dentry);
 323                 if (!err) {
 324                         inode->i_size = 0;
 325                         inode_dec_link_count(inode);
 326                         inode_dec_link_count(dir);
 327                 }
 328         }
 329         return err;
 330 }
 331
 332 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 333         struct inode * new_dir, struct dentry * new_dentry )
 334 {
 335         struct inode * old_inode = d_inode(old_dentry);
 336         struct inode * new_inode = d_inode(new_dentry);
 337         struct page * dir_page = NULL;
 338         struct ext2_dir_entry_2 * dir_de = NULL;
 339         struct page * old_page;
 340         struct ext2_dir_entry_2 * old_de;
 341         int err;
 342
 343         err = dquot_initialize(old_dir);
 344         if (err)
 345                 goto out;
 346
 347         err = dquot_initialize(new_dir);
 348         if (err)
 349                 goto out;
 350
 351         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 352         if (!old_de) {
 353                 err = -ENOENT;
 354                 goto out;
 355         }
 356
 357         if (S_ISDIR(old_inode->i_mode)) {
 358                 err = -EIO;
 359                 dir_de = ext2_dotdot(old_inode, &dir_page);
 360                 if (!dir_de)
 361                         goto out_old;
 362         }
 363
 364         if (new_inode) {
 365                 struct page *new_page;
 366                 struct ext2_dir_entry_2 *new_de;
 367
 368                 err = -ENOTEMPTY;
 369                 if (dir_de && !ext2_empty_dir (new_inode))
 370                         goto out_dir;
 371
 372                 err = -ENOENT;
 373                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 374                 if (!new_de)
 375                         goto out_dir;
 376                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 377                 new_inode->i_ctime = CURRENT_TIME_SEC;
 378                 if (dir_de)
 379                         drop_nlink(new_inode);
 380                 inode_dec_link_count(new_inode);
 381         } else {
 382                 err = ext2_add_link(new_dentry, old_inode);
 383                 if (err)
 384                         goto out_dir;
 385                 if (dir_de)
 386                         inode_inc_link_count(new_dir);
 387         }
 388
 389         /*
 390          * Like most other Unix systems, set the ctime for inodes on a
 391          * rename.
 392          */
 393         old_inode->i_ctime = CURRENT_TIME_SEC;
 394         mark_inode_dirty(old_inode);
 395
 396         ext2_delete_entry (old_de, old_page);
 397
 398         if (dir_de) {
 399                 if (old_dir != new_dir)
 400                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 401                 else {
 402                         kunmap(dir_page);
 403                         page_cache_release(dir_page);
 404                 }
 405                 inode_dec_link_count(old_dir);
 406         }
 407         return 0;
 408
 409
 410 out_dir:
 411         if (dir_de) {
 412                 kunmap(dir_page);
 413                 page_cache_release(dir_page);
 414         }
 415 out_old:
 416         kunmap(old_page);
 417         page_cache_release(old_page);
 418 out:
 419         return err;
 420 }
 421
 422 const struct inode_operations ext2_dir_inode_operations = {
 423         .create         = ext2_create,
 424         .lookup         = ext2_lookup,
 425         .link           = ext2_link,
 426         .unlink         = ext2_unlink,
 427         .symlink        = ext2_symlink,
 428         .mkdir          = ext2_mkdir,
 429         .rmdir          = ext2_rmdir,
 430         .mknod          = ext2_mknod,
 431         .rename         = ext2_rename,
 432 #ifdef CONFIG_EXT2_FS_XATTR
 433         .setxattr       = generic_setxattr,
 434         .getxattr       = generic_getxattr,
 435         .listxattr      = ext2_listxattr,
 436         .removexattr    = generic_removexattr,
 437 #endif
 438         .setattr        = ext2_setattr,
 439         .get_acl        = ext2_get_acl,
 440         .set_acl        = ext2_set_acl,
 441         .tmpfile        = ext2_tmpfile,
 442 };
 443
 444 const struct inode_operations ext2_special_inode_operations = {
 445 #ifdef CONFIG_EXT2_FS_XATTR
 446         .setxattr       = generic_setxattr,
 447         .getxattr       = generic_getxattr,
 448         .listxattr      = ext2_listxattr,
 449         .removexattr    = generic_removexattr,
 450 #endif
 451         .setattr        = ext2_setattr,
 452         .get_acl        = ext2_get_acl,
 453         .set_acl        = ext2_set_acl,
 454 };