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 #include "xip.h"
  39
  40 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  41 {
  42         int err = ext2_add_link(dentry, inode);
  43         if (!err) {
  44                 unlock_new_inode(inode);
  45                 d_instantiate(dentry, inode);
  46                 return 0;
  47         }
  48         inode_dec_link_count(inode);
  49         unlock_new_inode(inode);
  50         iput(inode);
  51         return err;
  52 }
  53
  54 /*
  55  * Methods themselves.
  56  */
  57
  58 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
  59 {
  60         struct inode * inode;
  61         ino_t ino;
  62
  63         if (dentry->d_name.len > EXT2_NAME_LEN)
  64                 return ERR_PTR(-ENAMETOOLONG);
  65
  66         ino = ext2_inode_by_name(dir, &dentry->d_name);
  67         inode = NULL;
  68         if (ino) {
  69                 inode = ext2_iget(dir->i_sb, ino);
  70                 if (inode == ERR_PTR(-ESTALE)) {
  71                         ext2_error(dir->i_sb, __func__,
  72                                         "deleted inode referenced: %lu",
  73                                         (unsigned long) ino);
  74                         return ERR_PTR(-EIO);
  75                 }
  76         }
  77         return d_splice_alias(inode, dentry);
  78 }
  79
  80 struct dentry *ext2_get_parent(struct dentry *child)
  81 {
  82         struct qstr dotdot = QSTR_INIT("..", 2);
  83         unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
  84         if (!ino)
  85                 return ERR_PTR(-ENOENT);
  86         return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
  87 }
  88
  89 /*
  90  * By the time this is called, we already have created
  91  * the directory cache entry for the new file, but it
  92  * is so far negative - it has no inode.
  93  *
  94  * If the create succeeds, we fill in the inode information
  95  * with d_instantiate().
  96  */
  97 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
  98 {
  99         struct inode *inode;
 100
 101         dquot_initialize(dir);
 102
 103         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 104         if (IS_ERR(inode))
 105                 return PTR_ERR(inode);
 106
 107         inode->i_op = &ext2_file_inode_operations;
 108         if (ext2_use_xip(inode->i_sb)) {
 109                 inode->i_mapping->a_ops = &ext2_aops_xip;
 110                 inode->i_fop = &ext2_xip_file_operations;
 111         } else if (test_opt(inode->i_sb, NOBH)) {
 112                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 113                 inode->i_fop = &ext2_file_operations;
 114         } else {
 115                 inode->i_mapping->a_ops = &ext2_aops;
 116                 inode->i_fop = &ext2_file_operations;
 117         }
 118         mark_inode_dirty(inode);
 119         return ext2_add_nondir(dentry, inode);
 120 }
 121
 122 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 123 {
 124         struct inode * inode;
 125         int err;
 126
 127         if (!new_valid_dev(rdev))
 128                 return -EINVAL;
 129
 130         dquot_initialize(dir);
 131
 132         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 133         err = PTR_ERR(inode);
 134         if (!IS_ERR(inode)) {
 135                 init_special_inode(inode, inode->i_mode, rdev);
 136 #ifdef CONFIG_EXT2_FS_XATTR
 137                 inode->i_op = &ext2_special_inode_operations;
 138 #endif
 139                 mark_inode_dirty(inode);
 140                 err = ext2_add_nondir(dentry, inode);
 141         }
 142         return err;
 143 }
 144
 145 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 146         const char * symname)
 147 {
 148         struct super_block * sb = dir->i_sb;
 149         int err = -ENAMETOOLONG;
 150         unsigned l = strlen(symname)+1;
 151         struct inode * inode;
 152
 153         if (l > sb->s_blocksize)
 154                 goto out;
 155
 156         dquot_initialize(dir);
 157
 158         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 159         err = PTR_ERR(inode);
 160         if (IS_ERR(inode))
 161                 goto out;
 162
 163         if (l > sizeof (EXT2_I(inode)->i_data)) {
 164                 /* slow symlink */
 165                 inode->i_op = &ext2_symlink_inode_operations;
 166                 if (test_opt(inode->i_sb, NOBH))
 167                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 168                 else
 169                         inode->i_mapping->a_ops = &ext2_aops;
 170                 err = page_symlink(inode, symname, l);
 171                 if (err)
 172                         goto out_fail;
 173         } else {
 174                 /* fast symlink */
 175                 inode->i_op = &ext2_fast_symlink_inode_operations;
 176                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 177                 inode->i_size = l-1;
 178         }
 179         mark_inode_dirty(inode);
 180
 181         err = ext2_add_nondir(dentry, inode);
 182 out:
 183         return err;
 184
 185 out_fail:
 186         inode_dec_link_count(inode);
 187         unlock_new_inode(inode);
 188         iput (inode);
 189         goto out;
 190 }
 191
 192 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 193         struct dentry *dentry)
 194 {
 195         struct inode *inode = old_dentry->d_inode;
 196         int err;
 197
 198         dquot_initialize(dir);
 199
 200         inode->i_ctime = CURRENT_TIME_SEC;
 201         inode_inc_link_count(inode);
 202         ihold(inode);
 203
 204         err = ext2_add_link(dentry, inode);
 205         if (!err) {
 206                 d_instantiate(dentry, inode);
 207                 return 0;
 208         }
 209         inode_dec_link_count(inode);
 210         iput(inode);
 211         return err;
 212 }
 213
 214 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 215 {
 216         struct inode * inode;
 217         int err;
 218
 219         dquot_initialize(dir);
 220
 221         inode_inc_link_count(dir);
 222
 223         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 224         err = PTR_ERR(inode);
 225         if (IS_ERR(inode))
 226                 goto out_dir;
 227
 228         inode->i_op = &ext2_dir_inode_operations;
 229         inode->i_fop = &ext2_dir_operations;
 230         if (test_opt(inode->i_sb, NOBH))
 231                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 232         else
 233                 inode->i_mapping->a_ops = &ext2_aops;
 234
 235         inode_inc_link_count(inode);
 236
 237         err = ext2_make_empty(inode, dir);
 238         if (err)
 239                 goto out_fail;
 240
 241         err = ext2_add_link(dentry, inode);
 242         if (err)
 243                 goto out_fail;
 244
 245         unlock_new_inode(inode);
 246         d_instantiate(dentry, inode);
 247 out:
 248         return err;
 249
 250 out_fail:
 251         inode_dec_link_count(inode);
 252         inode_dec_link_count(inode);
 253         unlock_new_inode(inode);
 254         iput(inode);
 255 out_dir:
 256         inode_dec_link_count(dir);
 257         goto out;
 258 }
 259
 260 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 261 {
 262         struct inode * inode = dentry->d_inode;
 263         struct ext2_dir_entry_2 * de;
 264         struct page * page;
 265         int err = -ENOENT;
 266
 267         dquot_initialize(dir);
 268
 269         de = ext2_find_entry (dir, &dentry->d_name, &page);
 270         if (!de)
 271                 goto out;
 272
 273         err = ext2_delete_entry (de, page);
 274         if (err)
 275                 goto out;
 276
 277         inode->i_ctime = dir->i_ctime;
 278         inode_dec_link_count(inode);
 279         err = 0;
 280 out:
 281         return err;
 282 }
 283
 284 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 285 {
 286         struct inode * inode = dentry->d_inode;
 287         int err = -ENOTEMPTY;
 288
 289         if (ext2_empty_dir(inode)) {
 290                 err = ext2_unlink(dir, dentry);
 291                 if (!err) {
 292                         inode->i_size = 0;
 293                         inode_dec_link_count(inode);
 294                         inode_dec_link_count(dir);
 295                 }
 296         }
 297         return err;
 298 }
 299
 300 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 301         struct inode * new_dir, struct dentry * new_dentry )
 302 {
 303         struct inode * old_inode = old_dentry->d_inode;
 304         struct inode * new_inode = new_dentry->d_inode;
 305         struct page * dir_page = NULL;
 306         struct ext2_dir_entry_2 * dir_de = NULL;
 307         struct page * old_page;
 308         struct ext2_dir_entry_2 * old_de;
 309         int err = -ENOENT;
 310
 311         dquot_initialize(old_dir);
 312         dquot_initialize(new_dir);
 313
 314         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 315         if (!old_de)
 316                 goto out;
 317
 318         if (S_ISDIR(old_inode->i_mode)) {
 319                 err = -EIO;
 320                 dir_de = ext2_dotdot(old_inode, &dir_page);
 321                 if (!dir_de)
 322                         goto out_old;
 323         }
 324
 325         if (new_inode) {
 326                 struct page *new_page;
 327                 struct ext2_dir_entry_2 *new_de;
 328
 329                 err = -ENOTEMPTY;
 330                 if (dir_de && !ext2_empty_dir (new_inode))
 331                         goto out_dir;
 332
 333                 err = -ENOENT;
 334                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 335                 if (!new_de)
 336                         goto out_dir;
 337                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 338                 new_inode->i_ctime = CURRENT_TIME_SEC;
 339                 if (dir_de)
 340                         drop_nlink(new_inode);
 341                 inode_dec_link_count(new_inode);
 342         } else {
 343                 err = ext2_add_link(new_dentry, old_inode);
 344                 if (err)
 345                         goto out_dir;
 346                 if (dir_de)
 347                         inode_inc_link_count(new_dir);
 348         }
 349
 350         /*
 351          * Like most other Unix systems, set the ctime for inodes on a
 352          * rename.
 353          */
 354         old_inode->i_ctime = CURRENT_TIME_SEC;
 355         mark_inode_dirty(old_inode);
 356
 357         ext2_delete_entry (old_de, old_page);
 358
 359         if (dir_de) {
 360                 if (old_dir != new_dir)
 361                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 362                 else {
 363                         kunmap(dir_page);
 364                         page_cache_release(dir_page);
 365                 }
 366                 inode_dec_link_count(old_dir);
 367         }
 368         return 0;
 369
 370
 371 out_dir:
 372         if (dir_de) {
 373                 kunmap(dir_page);
 374                 page_cache_release(dir_page);
 375         }
 376 out_old:
 377         kunmap(old_page);
 378         page_cache_release(old_page);
 379 out:
 380         return err;
 381 }
 382
 383 const struct inode_operations ext2_dir_inode_operations = {
 384         .create         = ext2_create,
 385         .lookup         = ext2_lookup,
 386         .link           = ext2_link,
 387         .unlink         = ext2_unlink,
 388         .symlink        = ext2_symlink,
 389         .mkdir          = ext2_mkdir,
 390         .rmdir          = ext2_rmdir,
 391         .mknod          = ext2_mknod,
 392         .rename         = ext2_rename,
 393 #ifdef CONFIG_EXT2_FS_XATTR
 394         .setxattr       = generic_setxattr,
 395         .getxattr       = generic_getxattr,
 396         .listxattr      = ext2_listxattr,
 397         .removexattr    = generic_removexattr,
 398 #endif
 399         .setattr        = ext2_setattr,
 400         .get_acl        = ext2_get_acl,
 401 };
 402
 403 const struct inode_operations ext2_special_inode_operations = {
 404 #ifdef CONFIG_EXT2_FS_XATTR
 405         .setxattr       = generic_setxattr,
 406         .getxattr       = generic_getxattr,
 407         .listxattr      = ext2_listxattr,
 408         .removexattr    = generic_removexattr,
 409 #endif
 410         .setattr        = ext2_setattr,
 411         .get_acl        = ext2_get_acl,
 412 };