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 "ext2.h"
  35 #include "xattr.h"
  36 #include "acl.h"
  37
  38 /*
  39  * Couple of helper functions - make the code slightly cleaner.
  40  */
  41
  42 static inline void ext2_inc_count(struct inode *inode)
  43 {
  44         inode->i_nlink++;
  45         mark_inode_dirty(inode);
  46 }
  47
  48 static inline void ext2_dec_count(struct inode *inode)
  49 {
  50         inode->i_nlink--;
  51         mark_inode_dirty(inode);
  52 }
  53
  54 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  55 {
  56         int err = ext2_add_link(dentry, inode);
  57         if (!err) {
  58                 d_instantiate(dentry, inode);
  59                 return 0;
  60         }
  61         ext2_dec_count(inode);
  62         iput(inode);
  63         return err;
  64 }
  65
  66 /*
  67  * Methods themselves.
  68  */
  69
  70 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  71 {
  72         struct inode * inode;
  73         ino_t ino;
  74
  75         if (dentry->d_name.len > EXT2_NAME_LEN)
  76                 return ERR_PTR(-ENAMETOOLONG);
  77
  78         ino = ext2_inode_by_name(dir, dentry);
  79         inode = NULL;
  80         if (ino) {
  81                 inode = iget(dir->i_sb, ino);
  82                 if (!inode)
  83                         return ERR_PTR(-EACCES);
  84         }
  85         if (inode)
  86                 return d_splice_alias(inode, dentry);
  87         d_add(dentry, inode);
  88         return NULL;
  89 }
  90
  91 struct dentry *ext2_get_parent(struct dentry *child)
  92 {
  93         unsigned long ino;
  94         struct dentry *parent;
  95         struct inode *inode;
  96         struct dentry dotdot;
  97
  98         dotdot.d_name.name = "..";
  99         dotdot.d_name.len = 2;
 100
 101         ino = ext2_inode_by_name(child->d_inode, &dotdot);
 102         if (!ino)
 103                 return ERR_PTR(-ENOENT);
 104         inode = iget(child->d_inode->i_sb, ino);
 105
 106         if (!inode)
 107                 return ERR_PTR(-EACCES);
 108         parent = d_alloc_anon(inode);
 109         if (!parent) {
 110                 iput(inode);
 111                 parent = ERR_PTR(-ENOMEM);
 112         }
 113         return parent;
 114 }
 115
 116 /*
 117  * By the time this is called, we already have created
 118  * the directory cache entry for the new file, but it
 119  * is so far negative - it has no inode.
 120  *
 121  * If the create succeeds, we fill in the inode information
 122  * with d_instantiate().
 123  */
 124 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
 125 {
 126         struct inode * inode = ext2_new_inode (dir, mode);
 127         int err = PTR_ERR(inode);
 128         if (!IS_ERR(inode)) {
 129                 inode->i_op = &ext2_file_inode_operations;
 130                 inode->i_fop = &ext2_file_operations;
 131                 if (test_opt(inode->i_sb, NOBH))
 132                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 133                 else
 134                         inode->i_mapping->a_ops = &ext2_aops;
 135                 mark_inode_dirty(inode);
 136                 err = ext2_add_nondir(dentry, inode);
 137         }
 138         return err;
 139 }
 140
 141 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 142 {
 143         struct inode * inode;
 144         int err;
 145
 146         if (!new_valid_dev(rdev))
 147                 return -EINVAL;
 148
 149         inode = ext2_new_inode (dir, mode);
 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         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 174         err = PTR_ERR(inode);
 175         if (IS_ERR(inode))
 176                 goto out;
 177
 178         if (l > sizeof (EXT2_I(inode)->i_data)) {
 179                 /* slow symlink */
 180                 inode->i_op = &ext2_symlink_inode_operations;
 181                 if (test_opt(inode->i_sb, NOBH))
 182                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 183                 else
 184                         inode->i_mapping->a_ops = &ext2_aops;
 185                 err = page_symlink(inode, symname, l);
 186                 if (err)
 187                         goto out_fail;
 188         } else {
 189                 /* fast symlink */
 190                 inode->i_op = &ext2_fast_symlink_inode_operations;
 191                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 192                 inode->i_size = l-1;
 193         }
 194         mark_inode_dirty(inode);
 195
 196         err = ext2_add_nondir(dentry, inode);
 197 out:
 198         return err;
 199
 200 out_fail:
 201         ext2_dec_count(inode);
 202         iput (inode);
 203         goto out;
 204 }
 205
 206 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 207         struct dentry *dentry)
 208 {
 209         struct inode *inode = old_dentry->d_inode;
 210
 211         if (inode->i_nlink >= EXT2_LINK_MAX)
 212                 return -EMLINK;
 213
 214         inode->i_ctime = CURRENT_TIME_SEC;
 215         ext2_inc_count(inode);
 216         atomic_inc(&inode->i_count);
 217
 218         return ext2_add_nondir(dentry, inode);
 219 }
 220
 221 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 222 {
 223         struct inode * inode;
 224         int err = -EMLINK;
 225
 226         if (dir->i_nlink >= EXT2_LINK_MAX)
 227                 goto out;
 228
 229         ext2_inc_count(dir);
 230
 231         inode = ext2_new_inode (dir, S_IFDIR | mode);
 232         err = PTR_ERR(inode);
 233         if (IS_ERR(inode))
 234                 goto out_dir;
 235
 236         inode->i_op = &ext2_dir_inode_operations;
 237         inode->i_fop = &ext2_dir_operations;
 238         if (test_opt(inode->i_sb, NOBH))
 239                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 240         else
 241                 inode->i_mapping->a_ops = &ext2_aops;
 242
 243         ext2_inc_count(inode);
 244
 245         err = ext2_make_empty(inode, dir);
 246         if (err)
 247                 goto out_fail;
 248
 249         err = ext2_add_link(dentry, inode);
 250         if (err)
 251                 goto out_fail;
 252
 253         d_instantiate(dentry, inode);
 254 out:
 255         return err;
 256
 257 out_fail:
 258         ext2_dec_count(inode);
 259         ext2_dec_count(inode);
 260         iput(inode);
 261 out_dir:
 262         ext2_dec_count(dir);
 263         goto out;
 264 }
 265
 266 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 267 {
 268         struct inode * inode = dentry->d_inode;
 269         struct ext2_dir_entry_2 * de;
 270         struct page * page;
 271         int err = -ENOENT;
 272
 273         de = ext2_find_entry (dir, dentry, &page);
 274         if (!de)
 275                 goto out;
 276
 277         err = ext2_delete_entry (de, page);
 278         if (err)
 279                 goto out;
 280
 281         inode->i_ctime = dir->i_ctime;
 282         ext2_dec_count(inode);
 283         err = 0;
 284 out:
 285         return err;
 286 }
 287
 288 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 289 {
 290         struct inode * inode = dentry->d_inode;
 291         int err = -ENOTEMPTY;
 292
 293         if (ext2_empty_dir(inode)) {
 294                 err = ext2_unlink(dir, dentry);
 295                 if (!err) {
 296                         inode->i_size = 0;
 297                         ext2_dec_count(inode);
 298                         ext2_dec_count(dir);
 299                 }
 300         }
 301         return err;
 302 }
 303
 304 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 305         struct inode * new_dir, struct dentry * new_dentry )
 306 {
 307         struct inode * old_inode = old_dentry->d_inode;
 308         struct inode * new_inode = new_dentry->d_inode;
 309         struct page * dir_page = NULL;
 310         struct ext2_dir_entry_2 * dir_de = NULL;
 311         struct page * old_page;
 312         struct ext2_dir_entry_2 * old_de;
 313         int err = -ENOENT;
 314
 315         old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
 316         if (!old_de)
 317                 goto out;
 318
 319         if (S_ISDIR(old_inode->i_mode)) {
 320                 err = -EIO;
 321                 dir_de = ext2_dotdot(old_inode, &dir_page);
 322                 if (!dir_de)
 323                         goto out_old;
 324         }
 325
 326         if (new_inode) {
 327                 struct page *new_page;
 328                 struct ext2_dir_entry_2 *new_de;
 329
 330                 err = -ENOTEMPTY;
 331                 if (dir_de && !ext2_empty_dir (new_inode))
 332                         goto out_dir;
 333
 334                 err = -ENOENT;
 335                 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
 336                 if (!new_de)
 337                         goto out_dir;
 338                 ext2_inc_count(old_inode);
 339                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 340                 new_inode->i_ctime = CURRENT_TIME_SEC;
 341                 if (dir_de)
 342                         new_inode->i_nlink--;
 343                 ext2_dec_count(new_inode);
 344         } else {
 345                 if (dir_de) {
 346                         err = -EMLINK;
 347                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 348                                 goto out_dir;
 349                 }
 350                 ext2_inc_count(old_inode);
 351                 err = ext2_add_link(new_dentry, old_inode);
 352                 if (err) {
 353                         ext2_dec_count(old_inode);
 354                         goto out_dir;
 355                 }
 356                 if (dir_de)
 357                         ext2_inc_count(new_dir);
 358         }
 359
 360         /*
 361          * Like most other Unix systems, set the ctime for inodes on a
 362          * rename.
 363          * ext2_dec_count() will mark the inode dirty.
 364          */
 365         old_inode->i_ctime = CURRENT_TIME_SEC;
 366
 367         ext2_delete_entry (old_de, old_page);
 368         ext2_dec_count(old_inode);
 369
 370         if (dir_de) {
 371                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 372                 ext2_dec_count(old_dir);
 373         }
 374         return 0;
 375
 376
 377 out_dir:
 378         if (dir_de) {
 379                 kunmap(dir_page);
 380                 page_cache_release(dir_page);
 381         }
 382 out_old:
 383         kunmap(old_page);
 384         page_cache_release(old_page);
 385 out:
 386         return err;
 387 }
 388
 389 struct inode_operations ext2_dir_inode_operations = {
 390         .create         = ext2_create,
 391         .lookup         = ext2_lookup,
 392         .link           = ext2_link,
 393         .unlink         = ext2_unlink,
 394         .symlink        = ext2_symlink,
 395         .mkdir          = ext2_mkdir,
 396         .rmdir          = ext2_rmdir,
 397         .mknod          = ext2_mknod,
 398         .rename         = ext2_rename,
 399 #ifdef CONFIG_EXT2_FS_XATTR
 400         .setxattr       = generic_setxattr,
 401         .getxattr       = generic_getxattr,
 402         .listxattr      = ext2_listxattr,
 403         .removexattr    = generic_removexattr,
 404 #endif
 405         .setattr        = ext2_setattr,
 406         .permission     = ext2_permission,
 407 };
 408
 409 struct inode_operations ext2_special_inode_operations = {
 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         .permission     = ext2_permission,
 418 };