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 = ext2_iget(dir->i_sb, ino);
  67                 if (IS_ERR(inode))
  68                         return ERR_CAST(inode);
  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 dotdot;
  77
  78         dotdot.d_name.name = "..";
  79         dotdot.d_name.len = 2;
  80
  81         ino = ext2_inode_by_name(child->d_inode, &dotdot);
  82         if (!ino)
  83                 return ERR_PTR(-ENOENT);
  84         return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
  85 }
  86
  87 /*
  88  * By the time this is called, we already have created
  89  * the directory cache entry for the new file, but it
  90  * is so far negative - it has no inode.
  91  *
  92  * If the create succeeds, we fill in the inode information
  93  * with d_instantiate().
  94  */
  95 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
  96 {
  97         struct inode * inode = ext2_new_inode (dir, mode);
  98         int err = PTR_ERR(inode);
  99         if (!IS_ERR(inode)) {
 100                 inode->i_op = &ext2_file_inode_operations;
 101                 if (ext2_use_xip(inode->i_sb)) {
 102                         inode->i_mapping->a_ops = &ext2_aops_xip;
 103                         inode->i_fop = &ext2_xip_file_operations;
 104                 } else if (test_opt(inode->i_sb, NOBH)) {
 105                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 106                         inode->i_fop = &ext2_file_operations;
 107                 } else {
 108                         inode->i_mapping->a_ops = &ext2_aops;
 109                         inode->i_fop = &ext2_file_operations;
 110                 }
 111                 mark_inode_dirty(inode);
 112                 err = ext2_add_nondir(dentry, inode);
 113         }
 114         return err;
 115 }
 116
 117 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 118 {
 119         struct inode * inode;
 120         int err;
 121
 122         if (!new_valid_dev(rdev))
 123                 return -EINVAL;
 124
 125         inode = ext2_new_inode (dir, mode);
 126         err = PTR_ERR(inode);
 127         if (!IS_ERR(inode)) {
 128                 init_special_inode(inode, inode->i_mode, rdev);
 129 #ifdef CONFIG_EXT2_FS_XATTR
 130                 inode->i_op = &ext2_special_inode_operations;
 131 #endif
 132                 mark_inode_dirty(inode);
 133                 err = ext2_add_nondir(dentry, inode);
 134         }
 135         return err;
 136 }
 137
 138 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 139         const char * symname)
 140 {
 141         struct super_block * sb = dir->i_sb;
 142         int err = -ENAMETOOLONG;
 143         unsigned l = strlen(symname)+1;
 144         struct inode * inode;
 145
 146         if (l > sb->s_blocksize)
 147                 goto out;
 148
 149         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 150         err = PTR_ERR(inode);
 151         if (IS_ERR(inode))
 152                 goto out;
 153
 154         if (l > sizeof (EXT2_I(inode)->i_data)) {
 155                 /* slow symlink */
 156                 inode->i_op = &ext2_symlink_inode_operations;
 157                 if (test_opt(inode->i_sb, NOBH))
 158                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 159                 else
 160                         inode->i_mapping->a_ops = &ext2_aops;
 161                 err = page_symlink(inode, symname, l);
 162                 if (err)
 163                         goto out_fail;
 164         } else {
 165                 /* fast symlink */
 166                 inode->i_op = &ext2_fast_symlink_inode_operations;
 167                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 168                 inode->i_size = l-1;
 169         }
 170         mark_inode_dirty(inode);
 171
 172         err = ext2_add_nondir(dentry, inode);
 173 out:
 174         return err;
 175
 176 out_fail:
 177         inode_dec_link_count(inode);
 178         iput (inode);
 179         goto out;
 180 }
 181
 182 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 183         struct dentry *dentry)
 184 {
 185         struct inode *inode = old_dentry->d_inode;
 186
 187         if (inode->i_nlink >= EXT2_LINK_MAX)
 188                 return -EMLINK;
 189
 190         inode->i_ctime = CURRENT_TIME_SEC;
 191         inode_inc_link_count(inode);
 192         atomic_inc(&inode->i_count);
 193
 194         return ext2_add_nondir(dentry, inode);
 195 }
 196
 197 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 198 {
 199         struct inode * inode;
 200         int err = -EMLINK;
 201
 202         if (dir->i_nlink >= EXT2_LINK_MAX)
 203                 goto out;
 204
 205         inode_inc_link_count(dir);
 206
 207         inode = ext2_new_inode (dir, S_IFDIR | mode);
 208         err = PTR_ERR(inode);
 209         if (IS_ERR(inode))
 210                 goto out_dir;
 211
 212         inode->i_op = &ext2_dir_inode_operations;
 213         inode->i_fop = &ext2_dir_operations;
 214         if (test_opt(inode->i_sb, NOBH))
 215                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 216         else
 217                 inode->i_mapping->a_ops = &ext2_aops;
 218
 219         inode_inc_link_count(inode);
 220
 221         err = ext2_make_empty(inode, dir);
 222         if (err)
 223                 goto out_fail;
 224
 225         err = ext2_add_link(dentry, inode);
 226         if (err)
 227                 goto out_fail;
 228
 229         d_instantiate(dentry, inode);
 230 out:
 231         return err;
 232
 233 out_fail:
 234         inode_dec_link_count(inode);
 235         inode_dec_link_count(inode);
 236         iput(inode);
 237 out_dir:
 238         inode_dec_link_count(dir);
 239         goto out;
 240 }
 241
 242 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 243 {
 244         struct inode * inode = dentry->d_inode;
 245         struct ext2_dir_entry_2 * de;
 246         struct page * page;
 247         int err = -ENOENT;
 248
 249         de = ext2_find_entry (dir, dentry, &page);
 250         if (!de)
 251                 goto out;
 252
 253         err = ext2_delete_entry (de, page);
 254         if (err)
 255                 goto out;
 256
 257         inode->i_ctime = dir->i_ctime;
 258         inode_dec_link_count(inode);
 259         err = 0;
 260 out:
 261         return err;
 262 }
 263
 264 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 265 {
 266         struct inode * inode = dentry->d_inode;
 267         int err = -ENOTEMPTY;
 268
 269         if (ext2_empty_dir(inode)) {
 270                 err = ext2_unlink(dir, dentry);
 271                 if (!err) {
 272                         inode->i_size = 0;
 273                         inode_dec_link_count(inode);
 274                         inode_dec_link_count(dir);
 275                 }
 276         }
 277         return err;
 278 }
 279
 280 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 281         struct inode * new_dir, struct dentry * new_dentry )
 282 {
 283         struct inode * old_inode = old_dentry->d_inode;
 284         struct inode * new_inode = new_dentry->d_inode;
 285         struct page * dir_page = NULL;
 286         struct ext2_dir_entry_2 * dir_de = NULL;
 287         struct page * old_page;
 288         struct ext2_dir_entry_2 * old_de;
 289         int err = -ENOENT;
 290
 291         old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
 292         if (!old_de)
 293                 goto out;
 294
 295         if (S_ISDIR(old_inode->i_mode)) {
 296                 err = -EIO;
 297                 dir_de = ext2_dotdot(old_inode, &dir_page);
 298                 if (!dir_de)
 299                         goto out_old;
 300         }
 301
 302         if (new_inode) {
 303                 struct page *new_page;
 304                 struct ext2_dir_entry_2 *new_de;
 305
 306                 err = -ENOTEMPTY;
 307                 if (dir_de && !ext2_empty_dir (new_inode))
 308                         goto out_dir;
 309
 310                 err = -ENOENT;
 311                 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
 312                 if (!new_de)
 313                         goto out_dir;
 314                 inode_inc_link_count(old_inode);
 315                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 316                 new_inode->i_ctime = CURRENT_TIME_SEC;
 317                 if (dir_de)
 318                         drop_nlink(new_inode);
 319                 inode_dec_link_count(new_inode);
 320         } else {
 321                 if (dir_de) {
 322                         err = -EMLINK;
 323                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 324                                 goto out_dir;
 325                 }
 326                 inode_inc_link_count(old_inode);
 327                 err = ext2_add_link(new_dentry, old_inode);
 328                 if (err) {
 329                         inode_dec_link_count(old_inode);
 330                         goto out_dir;
 331                 }
 332                 if (dir_de)
 333                         inode_inc_link_count(new_dir);
 334         }
 335
 336         /*
 337          * Like most other Unix systems, set the ctime for inodes on a
 338          * rename.
 339          * inode_dec_link_count() will mark the inode dirty.
 340          */
 341         old_inode->i_ctime = CURRENT_TIME_SEC;
 342
 343         ext2_delete_entry (old_de, old_page);
 344         inode_dec_link_count(old_inode);
 345
 346         if (dir_de) {
 347                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 348                 inode_dec_link_count(old_dir);
 349         }
 350         return 0;
 351
 352
 353 out_dir:
 354         if (dir_de) {
 355                 kunmap(dir_page);
 356                 page_cache_release(dir_page);
 357         }
 358 out_old:
 359         kunmap(old_page);
 360         page_cache_release(old_page);
 361 out:
 362         return err;
 363 }
 364
 365 const struct inode_operations ext2_dir_inode_operations = {
 366         .create         = ext2_create,
 367         .lookup         = ext2_lookup,
 368         .link           = ext2_link,
 369         .unlink         = ext2_unlink,
 370         .symlink        = ext2_symlink,
 371         .mkdir          = ext2_mkdir,
 372         .rmdir          = ext2_rmdir,
 373         .mknod          = ext2_mknod,
 374         .rename         = ext2_rename,
 375 #ifdef CONFIG_EXT2_FS_XATTR
 376         .setxattr       = generic_setxattr,
 377         .getxattr       = generic_getxattr,
 378         .listxattr      = ext2_listxattr,
 379         .removexattr    = generic_removexattr,
 380 #endif
 381         .setattr        = ext2_setattr,
 382         .permission     = ext2_permission,
 383 };
 384
 385 const struct inode_operations ext2_special_inode_operations = {
 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 };