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                 d_instantiate_new(dentry, inode);
  44                 return 0;
  45         }
  46         inode_dec_link_count(inode);
  47         unlock_new_inode(inode);
  48         iput(inode);
  49         return err;
  50 }
  51
  52 /*
  53  * Methods themselves.
  54  */
  55
  56 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
  57 {
  58         struct inode * inode;
  59         ino_t ino;
  60
  61         if (dentry->d_name.len > EXT2_NAME_LEN)
  62                 return ERR_PTR(-ENAMETOOLONG);
  63
  64         ino = ext2_inode_by_name(dir, &dentry->d_name);
  65         inode = NULL;
  66         if (ino) {
  67                 inode = ext2_iget(dir->i_sb, ino);
  68                 if (inode == ERR_PTR(-ESTALE)) {
  69                         ext2_error(dir->i_sb, __func__,
  70                                         "deleted inode referenced: %lu",
  71                                         (unsigned long) ino);
  72                         return ERR_PTR(-EIO);
  73                 }
  74         }
  75         return d_splice_alias(inode, dentry);
  76 }
  77
  78 struct dentry *ext2_get_parent(struct dentry *child)
  79 {
  80         struct qstr dotdot = QSTR_INIT("..", 2);
  81         unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
  82         if (!ino)
  83                 return ERR_PTR(-ENOENT);
  84         return d_obtain_alias(ext2_iget(d_inode(child)->i_sb, ino));
  85 }
  86
  87 /*
  88  * By the time this is called, we already have created
  89  * the directory cache entry for the new file, but it
  90  * is so far negative - it has no inode.
  91  *
  92  * If the create succeeds, we fill in the inode information
  93  * with d_instantiate().
  94  */
  95 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
  96 {
  97         struct inode *inode;
  98         int err;
  99
 100         err = dquot_initialize(dir);
 101         if (err)
 102                 return err;
 103
 104         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 105         if (IS_ERR(inode))
 106                 return PTR_ERR(inode);
 107
 108         inode->i_op = &ext2_file_inode_operations;
 109         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         return ext2_add_nondir(dentry, inode);
 118 }
 119
 120 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 121 {
 122         struct inode *inode = ext2_new_inode(dir, mode, NULL);
 123         if (IS_ERR(inode))
 124                 return PTR_ERR(inode);
 125
 126         inode->i_op = &ext2_file_inode_operations;
 127         if (test_opt(inode->i_sb, NOBH)) {
 128                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 129                 inode->i_fop = &ext2_file_operations;
 130         } else {
 131                 inode->i_mapping->a_ops = &ext2_aops;
 132                 inode->i_fop = &ext2_file_operations;
 133         }
 134         mark_inode_dirty(inode);
 135         d_tmpfile(dentry, inode);
 136         unlock_new_inode(inode);
 137         return 0;
 138 }
 139
 140 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 141 {
 142         struct inode * inode;
 143         int err;
 144
 145         err = dquot_initialize(dir);
 146         if (err)
 147                 return err;
 148
 149         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 150         err = PTR_ERR(inode);
 151         if (!IS_ERR(inode)) {
 152                 init_special_inode(inode, inode->i_mode, rdev);
 153 #ifdef CONFIG_EXT2_FS_XATTR
 154                 inode->i_op = &ext2_special_inode_operations;
 155 #endif
 156                 mark_inode_dirty(inode);
 157                 err = ext2_add_nondir(dentry, inode);
 158         }
 159         return err;
 160 }
 161
 162 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 163         const char * symname)
 164 {
 165         struct super_block * sb = dir->i_sb;
 166         int err = -ENAMETOOLONG;
 167         unsigned l = strlen(symname)+1;
 168         struct inode * inode;
 169
 170         if (l > sb->s_blocksize)
 171                 goto out;
 172
 173         err = dquot_initialize(dir);
 174         if (err)
 175                 goto out;
 176
 177         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 178         err = PTR_ERR(inode);
 179         if (IS_ERR(inode))
 180                 goto out;
 181
 182         if (l > sizeof (EXT2_I(inode)->i_data)) {
 183                 /* slow symlink */
 184                 inode->i_op = &ext2_symlink_inode_operations;
 185                 if (test_opt(inode->i_sb, NOBH))
 186                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 187                 else
 188                         inode->i_mapping->a_ops = &ext2_aops;
 189                 err = page_symlink(inode, symname, l);
 190                 if (err)
 191                         goto out_fail;
 192         } else {
 193                 /* fast symlink */
 194                 inode->i_op = &ext2_fast_symlink_inode_operations;
 195                 inode->i_link = (char*)EXT2_I(inode)->i_data;
 196                 memcpy(inode->i_link, symname, l);
 197                 inode->i_size = l-1;
 198         }
 199         mark_inode_dirty(inode);
 200
 201         err = ext2_add_nondir(dentry, inode);
 202 out:
 203         return err;
 204
 205 out_fail:
 206         inode_dec_link_count(inode);
 207         unlock_new_inode(inode);
 208         iput (inode);
 209         goto out;
 210 }
 211
 212 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 213         struct dentry *dentry)
 214 {
 215         struct inode *inode = d_inode(old_dentry);
 216         int err;
 217
 218         err = dquot_initialize(dir);
 219         if (err)
 220                 return err;
 221
 222         inode->i_ctime = CURRENT_TIME_SEC;
 223         inode_inc_link_count(inode);
 224         ihold(inode);
 225
 226         err = ext2_add_link(dentry, inode);
 227         if (!err) {
 228                 d_instantiate(dentry, inode);
 229                 return 0;
 230         }
 231         inode_dec_link_count(inode);
 232         iput(inode);
 233         return err;
 234 }
 235
 236 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 237 {
 238         struct inode * inode;
 239         int err;
 240
 241         err = dquot_initialize(dir);
 242         if (err)
 243                 return err;
 244
 245         inode_inc_link_count(dir);
 246
 247         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 248         err = PTR_ERR(inode);
 249         if (IS_ERR(inode))
 250                 goto out_dir;
 251
 252         inode->i_op = &ext2_dir_inode_operations;
 253         inode->i_fop = &ext2_dir_operations;
 254         if (test_opt(inode->i_sb, NOBH))
 255                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 256         else
 257                 inode->i_mapping->a_ops = &ext2_aops;
 258
 259         inode_inc_link_count(inode);
 260
 261         err = ext2_make_empty(inode, dir);
 262         if (err)
 263                 goto out_fail;
 264
 265         err = ext2_add_link(dentry, inode);
 266         if (err)
 267                 goto out_fail;
 268
 269         d_instantiate_new(dentry, inode);
 270 out:
 271         return err;
 272
 273 out_fail:
 274         inode_dec_link_count(inode);
 275         inode_dec_link_count(inode);
 276         unlock_new_inode(inode);
 277         iput(inode);
 278 out_dir:
 279         inode_dec_link_count(dir);
 280         goto out;
 281 }
 282
 283 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 284 {
 285         struct inode * inode = d_inode(dentry);
 286         struct ext2_dir_entry_2 * de;
 287         struct page * page;
 288         int err;
 289
 290         err = dquot_initialize(dir);
 291         if (err)
 292                 goto out;
 293
 294         de = ext2_find_entry (dir, &dentry->d_name, &page);
 295         if (!de) {
 296                 err = -ENOENT;
 297                 goto out;
 298         }
 299
 300         err = ext2_delete_entry (de, page);
 301         if (err)
 302                 goto out;
 303
 304         inode->i_ctime = dir->i_ctime;
 305         inode_dec_link_count(inode);
 306         err = 0;
 307 out:
 308         return err;
 309 }
 310
 311 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 312 {
 313         struct inode * inode = d_inode(dentry);
 314         int err = -ENOTEMPTY;
 315
 316         if (ext2_empty_dir(inode)) {
 317                 err = ext2_unlink(dir, dentry);
 318                 if (!err) {
 319                         inode->i_size = 0;
 320                         inode_dec_link_count(inode);
 321                         inode_dec_link_count(dir);
 322                 }
 323         }
 324         return err;
 325 }
 326
 327 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 328         struct inode * new_dir, struct dentry * new_dentry )
 329 {
 330         struct inode * old_inode = d_inode(old_dentry);
 331         struct inode * new_inode = d_inode(new_dentry);
 332         struct page * dir_page = NULL;
 333         struct ext2_dir_entry_2 * dir_de = NULL;
 334         struct page * old_page;
 335         struct ext2_dir_entry_2 * old_de;
 336         int err;
 337
 338         err = dquot_initialize(old_dir);
 339         if (err)
 340                 goto out;
 341
 342         err = dquot_initialize(new_dir);
 343         if (err)
 344                 goto out;
 345
 346         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 347         if (!old_de) {
 348                 err = -ENOENT;
 349                 goto out;
 350         }
 351
 352         if (S_ISDIR(old_inode->i_mode)) {
 353                 err = -EIO;
 354                 dir_de = ext2_dotdot(old_inode, &dir_page);
 355                 if (!dir_de)
 356                         goto out_old;
 357         }
 358
 359         if (new_inode) {
 360                 struct page *new_page;
 361                 struct ext2_dir_entry_2 *new_de;
 362
 363                 err = -ENOTEMPTY;
 364                 if (dir_de && !ext2_empty_dir (new_inode))
 365                         goto out_dir;
 366
 367                 err = -ENOENT;
 368                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 369                 if (!new_de)
 370                         goto out_dir;
 371                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 372                 new_inode->i_ctime = CURRENT_TIME_SEC;
 373                 if (dir_de)
 374                         drop_nlink(new_inode);
 375                 inode_dec_link_count(new_inode);
 376         } else {
 377                 err = ext2_add_link(new_dentry, old_inode);
 378                 if (err)
 379                         goto out_dir;
 380                 if (dir_de)
 381                         inode_inc_link_count(new_dir);
 382         }
 383
 384         /*
 385          * Like most other Unix systems, set the ctime for inodes on a
 386          * rename.
 387          */
 388         old_inode->i_ctime = CURRENT_TIME_SEC;
 389         mark_inode_dirty(old_inode);
 390
 391         ext2_delete_entry (old_de, old_page);
 392
 393         if (dir_de) {
 394                 if (old_dir != new_dir)
 395                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 396                 else {
 397                         kunmap(dir_page);
 398                         page_cache_release(dir_page);
 399                 }
 400                 inode_dec_link_count(old_dir);
 401         }
 402         return 0;
 403
 404
 405 out_dir:
 406         if (dir_de) {
 407                 kunmap(dir_page);
 408                 page_cache_release(dir_page);
 409         }
 410 out_old:
 411         kunmap(old_page);
 412         page_cache_release(old_page);
 413 out:
 414         return err;
 415 }
 416
 417 const struct inode_operations ext2_dir_inode_operations = {
 418         .create         = ext2_create,
 419         .lookup         = ext2_lookup,
 420         .link           = ext2_link,
 421         .unlink         = ext2_unlink,
 422         .symlink        = ext2_symlink,
 423         .mkdir          = ext2_mkdir,
 424         .rmdir          = ext2_rmdir,
 425         .mknod          = ext2_mknod,
 426         .rename         = ext2_rename,
 427 #ifdef CONFIG_EXT2_FS_XATTR
 428         .setxattr       = generic_setxattr,
 429         .getxattr       = generic_getxattr,
 430         .listxattr      = ext2_listxattr,
 431         .removexattr    = generic_removexattr,
 432 #endif
 433         .setattr        = ext2_setattr,
 434         .get_acl        = ext2_get_acl,
 435         .set_acl        = ext2_set_acl,
 436         .tmpfile        = ext2_tmpfile,
 437 };
 438
 439 const struct inode_operations ext2_special_inode_operations = {
 440 #ifdef CONFIG_EXT2_FS_XATTR
 441         .setxattr       = generic_setxattr,
 442         .getxattr       = generic_getxattr,
 443         .listxattr      = ext2_listxattr,
 444         .removexattr    = generic_removexattr,
 445 #endif
 446         .setattr        = ext2_setattr,
 447         .get_acl        = ext2_get_acl,
 448         .set_acl        = ext2_set_acl,
 449 };