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