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 #include "xip.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(dentry, inode);
  44                 return 0;
  45         }
  46         inode_dec_link_count(inode);
  47         iput(inode);
  48         return err;
  49 }
  50
  51 /*
  52  * Methods themselves.
  53  */
  54
  55 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  56 {
  57         struct inode * inode;
  58         ino_t ino;
  59
  60         if (dentry->d_name.len > EXT2_NAME_LEN)
  61                 return ERR_PTR(-ENAMETOOLONG);
  62
  63         ino = ext2_inode_by_name(dir, dentry);
  64         inode = NULL;
  65         if (ino) {
  66                 inode = iget(dir->i_sb, ino);
  67                 if (!inode)
  68                         return ERR_PTR(-EACCES);
  69         }
  70         return d_splice_alias(inode, dentry);
  71 }
  72
  73 struct dentry *ext2_get_parent(struct dentry *child)
  74 {
  75         unsigned long ino;
  76         struct dentry *parent;
  77         struct inode *inode;
  78         struct dentry dotdot;
  79
  80         dotdot.d_name.name = "..";
  81         dotdot.d_name.len = 2;
  82
  83         ino = ext2_inode_by_name(child->d_inode, &dotdot);
  84         if (!ino)
  85                 return ERR_PTR(-ENOENT);
  86         inode = iget(child->d_inode->i_sb, ino);
  87
  88         if (!inode)
  89                 return ERR_PTR(-EACCES);
  90         parent = d_alloc_anon(inode);
  91         if (!parent) {
  92                 iput(inode);
  93                 parent = ERR_PTR(-ENOMEM);
  94         }
  95         return parent;
  96 }
  97
  98 /*
  99  * By the time this is called, we already have created
 100  * the directory cache entry for the new file, but it
 101  * is so far negative - it has no inode.
 102  *
 103  * If the create succeeds, we fill in the inode information
 104  * with d_instantiate().
 105  */
 106 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
 107 {
 108         struct inode * inode = ext2_new_inode (dir, mode);
 109         int err = PTR_ERR(inode);
 110         if (!IS_ERR(inode)) {
 111                 inode->i_op = &ext2_file_inode_operations;
 112                 if (ext2_use_xip(inode->i_sb)) {
 113                         inode->i_mapping->a_ops = &ext2_aops_xip;
 114                         inode->i_fop = &ext2_xip_file_operations;
 115                 } else if (test_opt(inode->i_sb, NOBH)) {
 116                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 117                         inode->i_fop = &ext2_file_operations;
 118                 } else {
 119                         inode->i_mapping->a_ops = &ext2_aops;
 120                         inode->i_fop = &ext2_file_operations;
 121                 }
 122                 mark_inode_dirty(inode);
 123                 err = ext2_add_nondir(dentry, inode);
 124         }
 125         return err;
 126 }
 127
 128 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 129 {
 130         struct inode * inode;
 131         int err;
 132
 133         if (!new_valid_dev(rdev))
 134                 return -EINVAL;
 135
 136         inode = ext2_new_inode (dir, mode);
 137         err = PTR_ERR(inode);
 138         if (!IS_ERR(inode)) {
 139                 init_special_inode(inode, inode->i_mode, rdev);
 140 #ifdef CONFIG_EXT2_FS_XATTR
 141                 inode->i_op = &ext2_special_inode_operations;
 142 #endif
 143                 mark_inode_dirty(inode);
 144                 err = ext2_add_nondir(dentry, inode);
 145         }
 146         return err;
 147 }
 148
 149 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 150         const char * symname)
 151 {
 152         struct super_block * sb = dir->i_sb;
 153         int err = -ENAMETOOLONG;
 154         unsigned l = strlen(symname)+1;
 155         struct inode * inode;
 156
 157         if (l > sb->s_blocksize)
 158                 goto out;
 159
 160         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 161         err = PTR_ERR(inode);
 162         if (IS_ERR(inode))
 163                 goto out;
 164
 165         if (l > sizeof (EXT2_I(inode)->i_data)) {
 166                 /* slow symlink */
 167                 inode->i_op = &ext2_symlink_inode_operations;
 168                 if (test_opt(inode->i_sb, NOBH))
 169                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 170                 else
 171                         inode->i_mapping->a_ops = &ext2_aops;
 172                 err = page_symlink(inode, symname, l);
 173                 if (err)
 174                         goto out_fail;
 175         } else {
 176                 /* fast symlink */
 177                 inode->i_op = &ext2_fast_symlink_inode_operations;
 178                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 179                 inode->i_size = l-1;
 180         }
 181         mark_inode_dirty(inode);
 182
 183         err = ext2_add_nondir(dentry, inode);
 184 out:
 185         return err;
 186
 187 out_fail:
 188         inode_dec_link_count(inode);
 189         iput (inode);
 190         goto out;
 191 }
 192
 193 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 194         struct dentry *dentry)
 195 {
 196         struct inode *inode = old_dentry->d_inode;
 197
 198         if (inode->i_nlink >= EXT2_LINK_MAX)
 199                 return -EMLINK;
 200
 201         inode->i_ctime = CURRENT_TIME_SEC;
 202         inode_inc_link_count(inode);
 203         atomic_inc(&inode->i_count);
 204
 205         return ext2_add_nondir(dentry, inode);
 206 }
 207
 208 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 209 {
 210         struct inode * inode;
 211         int err = -EMLINK;
 212
 213         if (dir->i_nlink >= EXT2_LINK_MAX)
 214                 goto out;
 215
 216         inode_inc_link_count(dir);
 217
 218         inode = ext2_new_inode (dir, S_IFDIR | mode);
 219         err = PTR_ERR(inode);
 220         if (IS_ERR(inode))
 221                 goto out_dir;
 222
 223         inode->i_op = &ext2_dir_inode_operations;
 224         inode->i_fop = &ext2_dir_operations;
 225         if (test_opt(inode->i_sb, NOBH))
 226                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 227         else
 228                 inode->i_mapping->a_ops = &ext2_aops;
 229
 230         inode_inc_link_count(inode);
 231
 232         err = ext2_make_empty(inode, dir);
 233         if (err)
 234                 goto out_fail;
 235
 236         err = ext2_add_link(dentry, inode);
 237         if (err)
 238                 goto out_fail;
 239
 240         d_instantiate(dentry, inode);
 241 out:
 242         return err;
 243
 244 out_fail:
 245         inode_dec_link_count(inode);
 246         inode_dec_link_count(inode);
 247         iput(inode);
 248 out_dir:
 249         inode_dec_link_count(dir);
 250         goto out;
 251 }
 252
 253 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 254 {
 255         struct inode * inode = dentry->d_inode;
 256         struct ext2_dir_entry_2 * de;
 257         struct page * page;
 258         int err = -ENOENT;
 259
 260         de = ext2_find_entry (dir, dentry, &page);
 261         if (!de)
 262                 goto out;
 263
 264         err = ext2_delete_entry (de, page);
 265         if (err)
 266                 goto out;
 267
 268         inode->i_ctime = dir->i_ctime;
 269         inode_dec_link_count(inode);
 270         err = 0;
 271 out:
 272         return err;
 273 }
 274
 275 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 276 {
 277         struct inode * inode = dentry->d_inode;
 278         int err = -ENOTEMPTY;
 279
 280         if (ext2_empty_dir(inode)) {
 281                 err = ext2_unlink(dir, dentry);
 282                 if (!err) {
 283                         inode->i_size = 0;
 284                         inode_dec_link_count(inode);
 285                         inode_dec_link_count(dir);
 286                 }
 287         }
 288         return err;
 289 }
 290
 291 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 292         struct inode * new_dir, struct dentry * new_dentry )
 293 {
 294         struct inode * old_inode = old_dentry->d_inode;
 295         struct inode * new_inode = new_dentry->d_inode;
 296         struct page * dir_page = NULL;
 297         struct ext2_dir_entry_2 * dir_de = NULL;
 298         struct page * old_page;
 299         struct ext2_dir_entry_2 * old_de;
 300         int err = -ENOENT;
 301
 302         old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
 303         if (!old_de)
 304                 goto out;
 305
 306         if (S_ISDIR(old_inode->i_mode)) {
 307                 err = -EIO;
 308                 dir_de = ext2_dotdot(old_inode, &dir_page);
 309                 if (!dir_de)
 310                         goto out_old;
 311         }
 312
 313         if (new_inode) {
 314                 struct page *new_page;
 315                 struct ext2_dir_entry_2 *new_de;
 316
 317                 err = -ENOTEMPTY;
 318                 if (dir_de && !ext2_empty_dir (new_inode))
 319                         goto out_dir;
 320
 321                 err = -ENOENT;
 322                 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
 323                 if (!new_de)
 324                         goto out_dir;
 325                 inode_inc_link_count(old_inode);
 326                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 327                 new_inode->i_ctime = CURRENT_TIME_SEC;
 328                 if (dir_de)
 329                         drop_nlink(new_inode);
 330                 inode_dec_link_count(new_inode);
 331         } else {
 332                 if (dir_de) {
 333                         err = -EMLINK;
 334                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 335                                 goto out_dir;
 336                 }
 337                 inode_inc_link_count(old_inode);
 338                 err = ext2_add_link(new_dentry, old_inode);
 339                 if (err) {
 340                         inode_dec_link_count(old_inode);
 341                         goto out_dir;
 342                 }
 343                 if (dir_de)
 344                         inode_inc_link_count(new_dir);
 345         }
 346
 347         /*
 348          * Like most other Unix systems, set the ctime for inodes on a
 349          * rename.
 350          * inode_dec_link_count() will mark the inode dirty.
 351          */
 352         old_inode->i_ctime = CURRENT_TIME_SEC;
 353
 354         ext2_delete_entry (old_de, old_page);
 355         inode_dec_link_count(old_inode);
 356
 357         if (dir_de) {
 358                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 359                 inode_dec_link_count(old_dir);
 360         }
 361         return 0;
 362
 363
 364 out_dir:
 365         if (dir_de) {
 366                 kunmap(dir_page);
 367                 page_cache_release(dir_page);
 368         }
 369 out_old:
 370         kunmap(old_page);
 371         page_cache_release(old_page);
 372 out:
 373         return err;
 374 }
 375
 376 struct inode_operations ext2_dir_inode_operations = {
 377         .create         = ext2_create,
 378         .lookup         = ext2_lookup,
 379         .link           = ext2_link,
 380         .unlink         = ext2_unlink,
 381         .symlink        = ext2_symlink,
 382         .mkdir          = ext2_mkdir,
 383         .rmdir          = ext2_rmdir,
 384         .mknod          = ext2_mknod,
 385         .rename         = ext2_rename,
 386 #ifdef CONFIG_EXT2_FS_XATTR
 387         .setxattr       = generic_setxattr,
 388         .getxattr       = generic_getxattr,
 389         .listxattr      = ext2_listxattr,
 390         .removexattr    = generic_removexattr,
 391 #endif
 392         .setattr        = ext2_setattr,
 393         .permission     = ext2_permission,
 394 };
 395
 396 struct inode_operations ext2_special_inode_operations = {
 397 #ifdef CONFIG_EXT2_FS_XATTR
 398         .setxattr       = generic_setxattr,
 399         .getxattr       = generic_getxattr,
 400         .listxattr      = ext2_listxattr,
 401         .removexattr    = generic_removexattr,
 402 #endif
 403         .setattr        = ext2_setattr,
 404         .permission     = ext2_permission,
 405 };