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                 unlock_new_inode(inode);
  45                 return 0;
  46         }
  47         inode_dec_link_count(inode);
  48         unlock_new_inode(inode);
  49         iput(inode);
  50         return err;
  51 }
  52
  53 /*
  54  * Methods themselves.
  55  */
  56
  57 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  58 {
  59         struct inode * inode;
  60         ino_t ino;
  61
  62         if (dentry->d_name.len > EXT2_NAME_LEN)
  63                 return ERR_PTR(-ENAMETOOLONG);
  64
  65         ino = ext2_inode_by_name(dir, &dentry->d_name);
  66         inode = NULL;
  67         if (ino) {
  68                 inode = ext2_iget(dir->i_sb, ino);
  69                 if (IS_ERR(inode))
  70                         return ERR_CAST(inode);
  71         }
  72         return d_splice_alias(inode, dentry);
  73 }
  74
  75 struct dentry *ext2_get_parent(struct dentry *child)
  76 {
  77         struct qstr dotdot = {.name = "..", .len = 2};
  78         unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
  79         if (!ino)
  80                 return ERR_PTR(-ENOENT);
  81         return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
  82 }
  83
  84 /*
  85  * By the time this is called, we already have created
  86  * the directory cache entry for the new file, but it
  87  * is so far negative - it has no inode.
  88  *
  89  * If the create succeeds, we fill in the inode information
  90  * with d_instantiate().
  91  */
  92 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
  93 {
  94         struct inode * inode = ext2_new_inode (dir, mode);
  95         int err = PTR_ERR(inode);
  96         if (!IS_ERR(inode)) {
  97                 inode->i_op = &ext2_file_inode_operations;
  98                 if (ext2_use_xip(inode->i_sb)) {
  99                         inode->i_mapping->a_ops = &ext2_aops_xip;
 100                         inode->i_fop = &ext2_xip_file_operations;
 101                 } else if (test_opt(inode->i_sb, NOBH)) {
 102                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 103                         inode->i_fop = &ext2_file_operations;
 104                 } else {
 105                         inode->i_mapping->a_ops = &ext2_aops;
 106                         inode->i_fop = &ext2_file_operations;
 107                 }
 108                 mark_inode_dirty(inode);
 109                 err = ext2_add_nondir(dentry, inode);
 110         }
 111         return err;
 112 }
 113
 114 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 115 {
 116         struct inode * inode;
 117         int err;
 118
 119         if (!new_valid_dev(rdev))
 120                 return -EINVAL;
 121
 122         inode = ext2_new_inode (dir, mode);
 123         err = PTR_ERR(inode);
 124         if (!IS_ERR(inode)) {
 125                 init_special_inode(inode, inode->i_mode, rdev);
 126 #ifdef CONFIG_EXT2_FS_XATTR
 127                 inode->i_op = &ext2_special_inode_operations;
 128 #endif
 129                 mark_inode_dirty(inode);
 130                 err = ext2_add_nondir(dentry, inode);
 131         }
 132         return err;
 133 }
 134
 135 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 136         const char * symname)
 137 {
 138         struct super_block * sb = dir->i_sb;
 139         int err = -ENAMETOOLONG;
 140         unsigned l = strlen(symname)+1;
 141         struct inode * inode;
 142
 143         if (l > sb->s_blocksize)
 144                 goto out;
 145
 146         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 147         err = PTR_ERR(inode);
 148         if (IS_ERR(inode))
 149                 goto out;
 150
 151         if (l > sizeof (EXT2_I(inode)->i_data)) {
 152                 /* slow symlink */
 153                 inode->i_op = &ext2_symlink_inode_operations;
 154                 if (test_opt(inode->i_sb, NOBH))
 155                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 156                 else
 157                         inode->i_mapping->a_ops = &ext2_aops;
 158                 err = page_symlink(inode, symname, l);
 159                 if (err)
 160                         goto out_fail;
 161         } else {
 162                 /* fast symlink */
 163                 inode->i_op = &ext2_fast_symlink_inode_operations;
 164                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 165                 inode->i_size = l-1;
 166         }
 167         mark_inode_dirty(inode);
 168
 169         err = ext2_add_nondir(dentry, inode);
 170 out:
 171         return err;
 172
 173 out_fail:
 174         inode_dec_link_count(inode);
 175         unlock_new_inode(inode);
 176         iput (inode);
 177         goto out;
 178 }
 179
 180 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 181         struct dentry *dentry)
 182 {
 183         struct inode *inode = old_dentry->d_inode;
 184         int err;
 185
 186         if (inode->i_nlink >= EXT2_LINK_MAX)
 187                 return -EMLINK;
 188
 189         inode->i_ctime = CURRENT_TIME_SEC;
 190         inode_inc_link_count(inode);
 191         atomic_inc(&inode->i_count);
 192
 193         err = ext2_add_link(dentry, inode);
 194         if (!err) {
 195                 d_instantiate(dentry, inode);
 196                 return 0;
 197         }
 198         inode_dec_link_count(inode);
 199         iput(inode);
 200         return err;
 201 }
 202
 203 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 204 {
 205         struct inode * inode;
 206         int err = -EMLINK;
 207
 208         if (dir->i_nlink >= EXT2_LINK_MAX)
 209                 goto out;
 210
 211         inode_inc_link_count(dir);
 212
 213         inode = ext2_new_inode (dir, S_IFDIR | mode);
 214         err = PTR_ERR(inode);
 215         if (IS_ERR(inode))
 216                 goto out_dir;
 217
 218         inode->i_op = &ext2_dir_inode_operations;
 219         inode->i_fop = &ext2_dir_operations;
 220         if (test_opt(inode->i_sb, NOBH))
 221                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 222         else
 223                 inode->i_mapping->a_ops = &ext2_aops;
 224
 225         inode_inc_link_count(inode);
 226
 227         err = ext2_make_empty(inode, dir);
 228         if (err)
 229                 goto out_fail;
 230
 231         err = ext2_add_link(dentry, inode);
 232         if (err)
 233                 goto out_fail;
 234
 235         d_instantiate(dentry, inode);
 236         unlock_new_inode(inode);
 237 out:
 238         return err;
 239
 240 out_fail:
 241         inode_dec_link_count(inode);
 242         inode_dec_link_count(inode);
 243         unlock_new_inode(inode);
 244         iput(inode);
 245 out_dir:
 246         inode_dec_link_count(dir);
 247         goto out;
 248 }
 249
 250 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 251 {
 252         struct inode * inode = dentry->d_inode;
 253         struct ext2_dir_entry_2 * de;
 254         struct page * page;
 255         int err = -ENOENT;
 256
 257         de = ext2_find_entry (dir, &dentry->d_name, &page);
 258         if (!de)
 259                 goto out;
 260
 261         err = ext2_delete_entry (de, page);
 262         if (err)
 263                 goto out;
 264
 265         inode->i_ctime = dir->i_ctime;
 266         inode_dec_link_count(inode);
 267         err = 0;
 268 out:
 269         return err;
 270 }
 271
 272 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 273 {
 274         struct inode * inode = dentry->d_inode;
 275         int err = -ENOTEMPTY;
 276
 277         if (ext2_empty_dir(inode)) {
 278                 err = ext2_unlink(dir, dentry);
 279                 if (!err) {
 280                         inode->i_size = 0;
 281                         inode_dec_link_count(inode);
 282                         inode_dec_link_count(dir);
 283                 }
 284         }
 285         return err;
 286 }
 287
 288 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 289         struct inode * new_dir, struct dentry * new_dentry )
 290 {
 291         struct inode * old_inode = old_dentry->d_inode;
 292         struct inode * new_inode = new_dentry->d_inode;
 293         struct page * dir_page = NULL;
 294         struct ext2_dir_entry_2 * dir_de = NULL;
 295         struct page * old_page;
 296         struct ext2_dir_entry_2 * old_de;
 297         int err = -ENOENT;
 298
 299         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 300         if (!old_de)
 301                 goto out;
 302
 303         if (S_ISDIR(old_inode->i_mode)) {
 304                 err = -EIO;
 305                 dir_de = ext2_dotdot(old_inode, &dir_page);
 306                 if (!dir_de)
 307                         goto out_old;
 308         }
 309
 310         if (new_inode) {
 311                 struct page *new_page;
 312                 struct ext2_dir_entry_2 *new_de;
 313
 314                 err = -ENOTEMPTY;
 315                 if (dir_de && !ext2_empty_dir (new_inode))
 316                         goto out_dir;
 317
 318                 err = -ENOENT;
 319                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 320                 if (!new_de)
 321                         goto out_dir;
 322                 inode_inc_link_count(old_inode);
 323                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 324                 new_inode->i_ctime = CURRENT_TIME_SEC;
 325                 if (dir_de)
 326                         drop_nlink(new_inode);
 327                 inode_dec_link_count(new_inode);
 328         } else {
 329                 if (dir_de) {
 330                         err = -EMLINK;
 331                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 332                                 goto out_dir;
 333                 }
 334                 inode_inc_link_count(old_inode);
 335                 err = ext2_add_link(new_dentry, old_inode);
 336                 if (err) {
 337                         inode_dec_link_count(old_inode);
 338                         goto out_dir;
 339                 }
 340                 if (dir_de)
 341                         inode_inc_link_count(new_dir);
 342         }
 343
 344         /*
 345          * Like most other Unix systems, set the ctime for inodes on a
 346          * rename.
 347          * inode_dec_link_count() will mark the inode dirty.
 348          */
 349         old_inode->i_ctime = CURRENT_TIME_SEC;
 350
 351         ext2_delete_entry (old_de, old_page);
 352         inode_dec_link_count(old_inode);
 353
 354         if (dir_de) {
 355                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 356                 inode_dec_link_count(old_dir);
 357         }
 358         return 0;
 359
 360
 361 out_dir:
 362         if (dir_de) {
 363                 kunmap(dir_page);
 364                 page_cache_release(dir_page);
 365         }
 366 out_old:
 367         kunmap(old_page);
 368         page_cache_release(old_page);
 369 out:
 370         return err;
 371 }
 372
 373 const struct inode_operations ext2_dir_inode_operations = {
 374         .create         = ext2_create,
 375         .lookup         = ext2_lookup,
 376         .link           = ext2_link,
 377         .unlink         = ext2_unlink,
 378         .symlink        = ext2_symlink,
 379         .mkdir          = ext2_mkdir,
 380         .rmdir          = ext2_rmdir,
 381         .mknod          = ext2_mknod,
 382         .rename         = ext2_rename,
 383 #ifdef CONFIG_EXT2_FS_XATTR
 384         .setxattr       = generic_setxattr,
 385         .getxattr       = generic_getxattr,
 386         .listxattr      = ext2_listxattr,
 387         .removexattr    = generic_removexattr,
 388 #endif
 389         .setattr        = ext2_setattr,
 390         .permission     = ext2_permission,
 391 };
 392
 393 const struct inode_operations ext2_special_inode_operations = {
 394 #ifdef CONFIG_EXT2_FS_XATTR
 395         .setxattr       = generic_setxattr,
 396         .getxattr       = generic_getxattr,
 397         .listxattr      = ext2_listxattr,
 398         .removexattr    = generic_removexattr,
 399 #endif
 400         .setattr        = ext2_setattr,
 401         .permission     = ext2_permission,
 402 };