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_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 123 {
 124         struct inode *inode = ext2_new_inode(dir, mode, NULL);
 125         if (IS_ERR(inode))
 126                 return PTR_ERR(inode);
 127
 128         inode->i_op = &ext2_file_inode_operations;
 129         if (ext2_use_xip(inode->i_sb)) {
 130                 inode->i_mapping->a_ops = &ext2_aops_xip;
 131                 inode->i_fop = &ext2_xip_file_operations;
 132         } else if (test_opt(inode->i_sb, NOBH)) {
 133                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 134                 inode->i_fop = &ext2_file_operations;
 135         } else {
 136                 inode->i_mapping->a_ops = &ext2_aops;
 137                 inode->i_fop = &ext2_file_operations;
 138         }
 139         mark_inode_dirty(inode);
 140         d_tmpfile(dentry, inode);
 141         unlock_new_inode(inode);
 142         return 0;
 143 }
 144
 145 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 146 {
 147         struct inode * inode;
 148         int err;
 149
 150         if (!new_valid_dev(rdev))
 151                 return -EINVAL;
 152
 153         dquot_initialize(dir);
 154
 155         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 156         err = PTR_ERR(inode);
 157         if (!IS_ERR(inode)) {
 158                 init_special_inode(inode, inode->i_mode, rdev);
 159 #ifdef CONFIG_EXT2_FS_XATTR
 160                 inode->i_op = &ext2_special_inode_operations;
 161 #endif
 162                 mark_inode_dirty(inode);
 163                 err = ext2_add_nondir(dentry, inode);
 164         }
 165         return err;
 166 }
 167
 168 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 169         const char * symname)
 170 {
 171         struct super_block * sb = dir->i_sb;
 172         int err = -ENAMETOOLONG;
 173         unsigned l = strlen(symname)+1;
 174         struct inode * inode;
 175
 176         if (l > sb->s_blocksize)
 177                 goto out;
 178
 179         dquot_initialize(dir);
 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                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 200                 inode->i_size = l-1;
 201         }
 202         mark_inode_dirty(inode);
 203
 204         err = ext2_add_nondir(dentry, inode);
 205 out:
 206         return err;
 207
 208 out_fail:
 209         inode_dec_link_count(inode);
 210         unlock_new_inode(inode);
 211         iput (inode);
 212         goto out;
 213 }
 214
 215 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 216         struct dentry *dentry)
 217 {
 218         struct inode *inode = old_dentry->d_inode;
 219         int err;
 220
 221         dquot_initialize(dir);
 222
 223         inode->i_ctime = CURRENT_TIME_SEC;
 224         inode_inc_link_count(inode);
 225         ihold(inode);
 226
 227         err = ext2_add_link(dentry, inode);
 228         if (!err) {
 229                 d_instantiate(dentry, inode);
 230                 return 0;
 231         }
 232         inode_dec_link_count(inode);
 233         iput(inode);
 234         return err;
 235 }
 236
 237 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 238 {
 239         struct inode * inode;
 240         int err;
 241
 242         dquot_initialize(dir);
 243
 244         inode_inc_link_count(dir);
 245
 246         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 247         err = PTR_ERR(inode);
 248         if (IS_ERR(inode))
 249                 goto out_dir;
 250
 251         inode->i_op = &ext2_dir_inode_operations;
 252         inode->i_fop = &ext2_dir_operations;
 253         if (test_opt(inode->i_sb, NOBH))
 254                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 255         else
 256                 inode->i_mapping->a_ops = &ext2_aops;
 257
 258         inode_inc_link_count(inode);
 259
 260         err = ext2_make_empty(inode, dir);
 261         if (err)
 262                 goto out_fail;
 263
 264         err = ext2_add_link(dentry, inode);
 265         if (err)
 266                 goto out_fail;
 267
 268         unlock_new_inode(inode);
 269         d_instantiate(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 = dentry->d_inode;
 286         struct ext2_dir_entry_2 * de;
 287         struct page * page;
 288         int err = -ENOENT;
 289
 290         dquot_initialize(dir);
 291
 292         de = ext2_find_entry (dir, &dentry->d_name, &page);
 293         if (!de)
 294                 goto out;
 295
 296         err = ext2_delete_entry (de, page);
 297         if (err)
 298                 goto out;
 299
 300         inode->i_ctime = dir->i_ctime;
 301         inode_dec_link_count(inode);
 302         err = 0;
 303 out:
 304         return err;
 305 }
 306
 307 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 308 {
 309         struct inode * inode = dentry->d_inode;
 310         int err = -ENOTEMPTY;
 311
 312         if (ext2_empty_dir(inode)) {
 313                 err = ext2_unlink(dir, dentry);
 314                 if (!err) {
 315                         inode->i_size = 0;
 316                         inode_dec_link_count(inode);
 317                         inode_dec_link_count(dir);
 318                 }
 319         }
 320         return err;
 321 }
 322
 323 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 324         struct inode * new_dir, struct dentry * new_dentry )
 325 {
 326         struct inode * old_inode = old_dentry->d_inode;
 327         struct inode * new_inode = new_dentry->d_inode;
 328         struct page * dir_page = NULL;
 329         struct ext2_dir_entry_2 * dir_de = NULL;
 330         struct page * old_page;
 331         struct ext2_dir_entry_2 * old_de;
 332         int err = -ENOENT;
 333
 334         dquot_initialize(old_dir);
 335         dquot_initialize(new_dir);
 336
 337         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 338         if (!old_de)
 339                 goto out;
 340
 341         if (S_ISDIR(old_inode->i_mode)) {
 342                 err = -EIO;
 343                 dir_de = ext2_dotdot(old_inode, &dir_page);
 344                 if (!dir_de)
 345                         goto out_old;
 346         }
 347
 348         if (new_inode) {
 349                 struct page *new_page;
 350                 struct ext2_dir_entry_2 *new_de;
 351
 352                 err = -ENOTEMPTY;
 353                 if (dir_de && !ext2_empty_dir (new_inode))
 354                         goto out_dir;
 355
 356                 err = -ENOENT;
 357                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 358                 if (!new_de)
 359                         goto out_dir;
 360                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 361                 new_inode->i_ctime = CURRENT_TIME_SEC;
 362                 if (dir_de)
 363                         drop_nlink(new_inode);
 364                 inode_dec_link_count(new_inode);
 365         } else {
 366                 err = ext2_add_link(new_dentry, old_inode);
 367                 if (err)
 368                         goto out_dir;
 369                 if (dir_de)
 370                         inode_inc_link_count(new_dir);
 371         }
 372
 373         /*
 374          * Like most other Unix systems, set the ctime for inodes on a
 375          * rename.
 376          */
 377         old_inode->i_ctime = CURRENT_TIME_SEC;
 378         mark_inode_dirty(old_inode);
 379
 380         ext2_delete_entry (old_de, old_page);
 381
 382         if (dir_de) {
 383                 if (old_dir != new_dir)
 384                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 385                 else {
 386                         kunmap(dir_page);
 387                         page_cache_release(dir_page);
 388                 }
 389                 inode_dec_link_count(old_dir);
 390         }
 391         return 0;
 392
 393
 394 out_dir:
 395         if (dir_de) {
 396                 kunmap(dir_page);
 397                 page_cache_release(dir_page);
 398         }
 399 out_old:
 400         kunmap(old_page);
 401         page_cache_release(old_page);
 402 out:
 403         return err;
 404 }
 405
 406 const struct inode_operations ext2_dir_inode_operations = {
 407         .create         = ext2_create,
 408         .lookup         = ext2_lookup,
 409         .link           = ext2_link,
 410         .unlink         = ext2_unlink,
 411         .symlink        = ext2_symlink,
 412         .mkdir          = ext2_mkdir,
 413         .rmdir          = ext2_rmdir,
 414         .mknod          = ext2_mknod,
 415         .rename         = ext2_rename,
 416 #ifdef CONFIG_EXT2_FS_XATTR
 417         .setxattr       = generic_setxattr,
 418         .getxattr       = generic_getxattr,
 419         .listxattr      = ext2_listxattr,
 420         .removexattr    = generic_removexattr,
 421 #endif
 422         .setattr        = ext2_setattr,
 423         .get_acl        = ext2_get_acl,
 424         .tmpfile        = ext2_tmpfile,
 425 };
 426
 427 const struct inode_operations ext2_special_inode_operations = {
 428 #ifdef CONFIG_EXT2_FS_XATTR
 429         .setxattr       = generic_setxattr,
 430         .getxattr       = generic_getxattr,
 431         .listxattr      = ext2_listxattr,
 432         .removexattr    = generic_removexattr,
 433 #endif
 434         .setattr        = ext2_setattr,
 435         .get_acl        = ext2_get_acl,
 436 };