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 viro@math.psu.edu
   6  *
   7  * Stuff here is basically a glue between the VFS and generic UNIXish
   8  * filesystem that keeps everything in pagecache. All knowledge of the
   9  * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
  10  * and it's easier to debug that way. In principle we might want to
  11  * generalize that a bit and turn it into a library. Or not.
  12  *
  13  * The only non-static object here is ext2_dir_inode_operations.
  14  *
  15  * TODO: get rid of kmap() use, add readahead.
  16  *
  17  * Copyright (C) 1992, 1993, 1994, 1995
  18  * Remy Card (card@masi.ibp.fr)
  19  * Laboratoire MASI - Institut Blaise Pascal
  20  * Universite Pierre et Marie Curie (Paris VI)
  21  *
  22  *  from
  23  *
  24  *  linux/fs/minix/namei.c
  25  *
  26  *  Copyright (C) 1991, 1992  Linus Torvalds
  27  *
  28  *  Big-endian to little-endian byte-swapping/bitmaps by
  29  *        David S. Miller (davem@caip.rutgers.edu), 1995
  30  */
  31
  32 #include <linux/pagemap.h>
  33 #include "ext2.h"
  34 #include "xattr.h"
  35 #include "acl.h"
  36
  37 /*
  38  * Couple of helper functions - make the code slightly cleaner.
  39  */
  40
  41 static inline void ext2_inc_count(struct inode *inode)
  42 {
  43         inode->i_nlink++;
  44         mark_inode_dirty(inode);
  45 }
  46
  47 static inline void ext2_dec_count(struct inode *inode)
  48 {
  49         inode->i_nlink--;
  50         mark_inode_dirty(inode);
  51 }
  52
  53 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  54 {
  55         int err = ext2_add_link(dentry, inode);
  56         if (!err) {
  57                 d_instantiate(dentry, inode);
  58                 return 0;
  59         }
  60         ext2_dec_count(inode);
  61         iput(inode);
  62         return err;
  63 }
  64
  65 /*
  66  * Methods themselves.
  67  */
  68
  69 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  70 {
  71         struct inode * inode;
  72         ino_t ino;
  73
  74         if (dentry->d_name.len > EXT2_NAME_LEN)
  75                 return ERR_PTR(-ENAMETOOLONG);
  76
  77         ino = ext2_inode_by_name(dir, dentry);
  78         inode = NULL;
  79         if (ino) {
  80                 inode = iget(dir->i_sb, ino);
  81                 if (!inode)
  82                         return ERR_PTR(-EACCES);
  83         }
  84         if (inode)
  85                 return d_splice_alias(inode, dentry);
  86         d_add(dentry, inode);
  87         return NULL;
  88 }
  89
  90 struct dentry *ext2_get_parent(struct dentry *child)
  91 {
  92         unsigned long ino;
  93         struct dentry *parent;
  94         struct inode *inode;
  95         struct dentry dotdot;
  96
  97         dotdot.d_name.name = "..";
  98         dotdot.d_name.len = 2;
  99
 100         ino = ext2_inode_by_name(child->d_inode, &dotdot);
 101         if (!ino)
 102                 return ERR_PTR(-ENOENT);
 103         inode = iget(child->d_inode->i_sb, ino);
 104
 105         if (!inode)
 106                 return ERR_PTR(-EACCES);
 107         parent = d_alloc_anon(inode);
 108         if (!parent) {
 109                 iput(inode);
 110                 parent = ERR_PTR(-ENOMEM);
 111         }
 112         return parent;
 113 }
 114
 115 /*
 116  * By the time this is called, we already have created
 117  * the directory cache entry for the new file, but it
 118  * is so far negative - it has no inode.
 119  *
 120  * If the create succeeds, we fill in the inode information
 121  * with d_instantiate().
 122  */
 123 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
 124 {
 125         struct inode * inode = ext2_new_inode (dir, mode);
 126         int err = PTR_ERR(inode);
 127         if (!IS_ERR(inode)) {
 128                 inode->i_op = &ext2_file_inode_operations;
 129                 inode->i_fop = &ext2_file_operations;
 130                 if (test_opt(inode->i_sb, NOBH))
 131                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 132                 else
 133                         inode->i_mapping->a_ops = &ext2_aops;
 134                 mark_inode_dirty(inode);
 135                 err = ext2_add_nondir(dentry, inode);
 136         }
 137         return err;
 138 }
 139
 140 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 141 {
 142         struct inode * inode;
 143         int err;
 144
 145         if (!new_valid_dev(rdev))
 146                 return -EINVAL;
 147
 148         inode = ext2_new_inode (dir, mode);
 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         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 173         err = PTR_ERR(inode);
 174         if (IS_ERR(inode))
 175                 goto out;
 176
 177         if (l > sizeof (EXT2_I(inode)->i_data)) {
 178                 /* slow symlink */
 179                 inode->i_op = &ext2_symlink_inode_operations;
 180                 if (test_opt(inode->i_sb, NOBH))
 181                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 182                 else
 183                         inode->i_mapping->a_ops = &ext2_aops;
 184                 err = page_symlink(inode, symname, l);
 185                 if (err)
 186                         goto out_fail;
 187         } else {
 188                 /* fast symlink */
 189                 inode->i_op = &ext2_fast_symlink_inode_operations;
 190                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 191                 inode->i_size = l-1;
 192         }
 193         mark_inode_dirty(inode);
 194
 195         err = ext2_add_nondir(dentry, inode);
 196 out:
 197         return err;
 198
 199 out_fail:
 200         ext2_dec_count(inode);
 201         iput (inode);
 202         goto out;
 203 }
 204
 205 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 206         struct dentry *dentry)
 207 {
 208         struct inode *inode = old_dentry->d_inode;
 209
 210         if (inode->i_nlink >= EXT2_LINK_MAX)
 211                 return -EMLINK;
 212
 213         inode->i_ctime = CURRENT_TIME;
 214         ext2_inc_count(inode);
 215         atomic_inc(&inode->i_count);
 216
 217         return ext2_add_nondir(dentry, inode);
 218 }
 219
 220 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 221 {
 222         struct inode * inode;
 223         int err = -EMLINK;
 224
 225         if (dir->i_nlink >= EXT2_LINK_MAX)
 226                 goto out;
 227
 228         ext2_inc_count(dir);
 229
 230         inode = ext2_new_inode (dir, S_IFDIR | mode);
 231         err = PTR_ERR(inode);
 232         if (IS_ERR(inode))
 233                 goto out_dir;
 234
 235         inode->i_op = &ext2_dir_inode_operations;
 236         inode->i_fop = &ext2_dir_operations;
 237         if (test_opt(inode->i_sb, NOBH))
 238                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 239         else
 240                 inode->i_mapping->a_ops = &ext2_aops;
 241
 242         ext2_inc_count(inode);
 243
 244         err = ext2_make_empty(inode, dir);
 245         if (err)
 246                 goto out_fail;
 247
 248         err = ext2_add_link(dentry, inode);
 249         if (err)
 250                 goto out_fail;
 251
 252         d_instantiate(dentry, inode);
 253 out:
 254         return err;
 255
 256 out_fail:
 257         ext2_dec_count(inode);
 258         ext2_dec_count(inode);
 259         iput(inode);
 260 out_dir:
 261         ext2_dec_count(dir);
 262         goto out;
 263 }
 264
 265 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 266 {
 267         struct inode * inode = dentry->d_inode;
 268         struct ext2_dir_entry_2 * de;
 269         struct page * page;
 270         int err = -ENOENT;
 271
 272         de = ext2_find_entry (dir, dentry, &page);
 273         if (!de)
 274                 goto out;
 275
 276         err = ext2_delete_entry (de, page);
 277         if (err)
 278                 goto out;
 279
 280         inode->i_ctime = dir->i_ctime;
 281         ext2_dec_count(inode);
 282         err = 0;
 283 out:
 284         return err;
 285 }
 286
 287 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 288 {
 289         struct inode * inode = dentry->d_inode;
 290         int err = -ENOTEMPTY;
 291
 292         if (ext2_empty_dir(inode)) {
 293                 err = ext2_unlink(dir, dentry);
 294                 if (!err) {
 295                         inode->i_size = 0;
 296                         ext2_dec_count(inode);
 297                         ext2_dec_count(dir);
 298                 }
 299         }
 300         return err;
 301 }
 302
 303 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 304         struct inode * new_dir, struct dentry * new_dentry )
 305 {
 306         struct inode * old_inode = old_dentry->d_inode;
 307         struct inode * new_inode = new_dentry->d_inode;
 308         struct page * dir_page = NULL;
 309         struct ext2_dir_entry_2 * dir_de = NULL;
 310         struct page * old_page;
 311         struct ext2_dir_entry_2 * old_de;
 312         int err = -ENOENT;
 313
 314         old_de = ext2_find_entry (old_dir, old_dentry, &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, &new_page);
 335                 if (!new_de)
 336                         goto out_dir;
 337                 ext2_inc_count(old_inode);
 338                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 339                 new_inode->i_ctime = CURRENT_TIME;
 340                 if (dir_de)
 341                         new_inode->i_nlink--;
 342                 ext2_dec_count(new_inode);
 343         } else {
 344                 if (dir_de) {
 345                         err = -EMLINK;
 346                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 347                                 goto out_dir;
 348                 }
 349                 ext2_inc_count(old_inode);
 350                 err = ext2_add_link(new_dentry, old_inode);
 351                 if (err) {
 352                         ext2_dec_count(old_inode);
 353                         goto out_dir;
 354                 }
 355                 if (dir_de)
 356                         ext2_inc_count(new_dir);
 357         }
 358
 359         /*
 360          * Like most other Unix systems, set the ctime for inodes on a
 361          * rename.
 362          * ext2_dec_count() will mark the inode dirty.
 363          */
 364         old_inode->i_ctime = CURRENT_TIME;
 365
 366         ext2_delete_entry (old_de, old_page);
 367         ext2_dec_count(old_inode);
 368
 369         if (dir_de) {
 370                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 371                 ext2_dec_count(old_dir);
 372         }
 373         return 0;
 374
 375
 376 out_dir:
 377         if (dir_de) {
 378                 kunmap(dir_page);
 379                 page_cache_release(dir_page);
 380         }
 381 out_old:
 382         kunmap(old_page);
 383         page_cache_release(old_page);
 384 out:
 385         return err;
 386 }
 387
 388 struct inode_operations ext2_dir_inode_operations = {
 389         .create         = ext2_create,
 390         .lookup         = ext2_lookup,
 391         .link           = ext2_link,
 392         .unlink         = ext2_unlink,
 393         .symlink        = ext2_symlink,
 394         .mkdir          = ext2_mkdir,
 395         .rmdir          = ext2_rmdir,
 396         .mknod          = ext2_mknod,
 397         .rename         = ext2_rename,
 398         .setxattr       = ext2_setxattr,
 399         .getxattr       = ext2_getxattr,
 400         .listxattr      = ext2_listxattr,
 401         .removexattr    = ext2_removexattr,
 402         .setattr        = ext2_setattr,
 403         .permission     = ext2_permission,
 404 };
 405
 406 struct inode_operations ext2_special_inode_operations = {
 407         .setxattr       = ext2_setxattr,
 408         .getxattr       = ext2_getxattr,
 409         .listxattr      = ext2_listxattr,
 410         .removexattr    = ext2_removexattr,
 411         .setattr        = ext2_setattr,
 412         .permission     = ext2_permission,
 413 };