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 <linux/quotaops.h>
  35 #include "ext2.h"
  36 #include "xattr.h"
  37 #include "acl.h"
  38 #include "xip.h"
  39
  40 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  41 {
  42         int err = ext2_add_link(dentry, inode);
  43         if (!err) {
  44                 d_instantiate(dentry, inode);
  45                 unlock_new_inode(inode);
  46                 return 0;
  47         }
  48         inode_dec_link_count(inode);
  49         unlock_new_inode(inode);
  50         iput(inode);
  51         return err;
  52 }
  53
  54 /*
  55  * Methods themselves.
  56  */
  57
  58 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  59 {
  60         struct inode * inode;
  61         ino_t ino;
  62
  63         if (dentry->d_name.len > EXT2_NAME_LEN)
  64                 return ERR_PTR(-ENAMETOOLONG);
  65
  66         ino = ext2_inode_by_name(dir, &dentry->d_name);
  67         inode = NULL;
  68         if (ino) {
  69                 inode = ext2_iget(dir->i_sb, ino);
  70                 if (unlikely(IS_ERR(inode))) {
  71                         if (PTR_ERR(inode) == -ESTALE) {
  72                                 ext2_error(dir->i_sb, __func__,
  73                                                 "deleted inode referenced: %lu",
  74                                                 (unsigned long) ino);
  75                                 return ERR_PTR(-EIO);
  76                         } else {
  77                                 return ERR_CAST(inode);
  78                         }
  79                 }
  80         }
  81         return d_splice_alias(inode, dentry);
  82 }
  83
  84 struct dentry *ext2_get_parent(struct dentry *child)
  85 {
  86         struct qstr dotdot = {.name = "..", .len = 2};
  87         unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
  88         if (!ino)
  89                 return ERR_PTR(-ENOENT);
  90         return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
  91 }
  92
  93 /*
  94  * By the time this is called, we already have created
  95  * the directory cache entry for the new file, but it
  96  * is so far negative - it has no inode.
  97  *
  98  * If the create succeeds, we fill in the inode information
  99  * with d_instantiate().
 100  */
 101 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
 102 {
 103         struct inode *inode;
 104
 105         dquot_initialize(dir);
 106
 107         inode = ext2_new_inode(dir, mode);
 108         if (IS_ERR(inode))
 109                 return PTR_ERR(inode);
 110
 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         return ext2_add_nondir(dentry, inode);
 124 }
 125
 126 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 127 {
 128         struct inode * inode;
 129         int err;
 130
 131         if (!new_valid_dev(rdev))
 132                 return -EINVAL;
 133
 134         dquot_initialize(dir);
 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         dquot_initialize(dir);
 161
 162         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 163         err = PTR_ERR(inode);
 164         if (IS_ERR(inode))
 165                 goto out;
 166
 167         if (l > sizeof (EXT2_I(inode)->i_data)) {
 168                 /* slow symlink */
 169                 inode->i_op = &ext2_symlink_inode_operations;
 170                 if (test_opt(inode->i_sb, NOBH))
 171                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 172                 else
 173                         inode->i_mapping->a_ops = &ext2_aops;
 174                 err = page_symlink(inode, symname, l);
 175                 if (err)
 176                         goto out_fail;
 177         } else {
 178                 /* fast symlink */
 179                 inode->i_op = &ext2_fast_symlink_inode_operations;
 180                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 181                 inode->i_size = l-1;
 182         }
 183         mark_inode_dirty(inode);
 184
 185         err = ext2_add_nondir(dentry, inode);
 186 out:
 187         return err;
 188
 189 out_fail:
 190         inode_dec_link_count(inode);
 191         unlock_new_inode(inode);
 192         iput (inode);
 193         goto out;
 194 }
 195
 196 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 197         struct dentry *dentry)
 198 {
 199         struct inode *inode = old_dentry->d_inode;
 200         int err;
 201
 202         if (inode->i_nlink >= EXT2_LINK_MAX)
 203                 return -EMLINK;
 204
 205         dquot_initialize(dir);
 206
 207         inode->i_ctime = CURRENT_TIME_SEC;
 208         inode_inc_link_count(inode);
 209         atomic_inc(&inode->i_count);
 210
 211         err = ext2_add_link(dentry, inode);
 212         if (!err) {
 213                 d_instantiate(dentry, inode);
 214                 return 0;
 215         }
 216         inode_dec_link_count(inode);
 217         iput(inode);
 218         return err;
 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         dquot_initialize(dir);
 230
 231         inode_inc_link_count(dir);
 232
 233         inode = ext2_new_inode (dir, S_IFDIR | mode);
 234         err = PTR_ERR(inode);
 235         if (IS_ERR(inode))
 236                 goto out_dir;
 237
 238         inode->i_op = &ext2_dir_inode_operations;
 239         inode->i_fop = &ext2_dir_operations;
 240         if (test_opt(inode->i_sb, NOBH))
 241                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 242         else
 243                 inode->i_mapping->a_ops = &ext2_aops;
 244
 245         inode_inc_link_count(inode);
 246
 247         err = ext2_make_empty(inode, dir);
 248         if (err)
 249                 goto out_fail;
 250
 251         err = ext2_add_link(dentry, inode);
 252         if (err)
 253                 goto out_fail;
 254
 255         d_instantiate(dentry, inode);
 256         unlock_new_inode(inode);
 257 out:
 258         return err;
 259
 260 out_fail:
 261         inode_dec_link_count(inode);
 262         inode_dec_link_count(inode);
 263         unlock_new_inode(inode);
 264         iput(inode);
 265 out_dir:
 266         inode_dec_link_count(dir);
 267         goto out;
 268 }
 269
 270 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 271 {
 272         struct inode * inode = dentry->d_inode;
 273         struct ext2_dir_entry_2 * de;
 274         struct page * page;
 275         int err = -ENOENT;
 276
 277         dquot_initialize(dir);
 278
 279         de = ext2_find_entry (dir, &dentry->d_name, &page);
 280         if (!de)
 281                 goto out;
 282
 283         err = ext2_delete_entry (de, page);
 284         if (err)
 285                 goto out;
 286
 287         inode->i_ctime = dir->i_ctime;
 288         inode_dec_link_count(inode);
 289         err = 0;
 290 out:
 291         return err;
 292 }
 293
 294 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 295 {
 296         struct inode * inode = dentry->d_inode;
 297         int err = -ENOTEMPTY;
 298
 299         if (ext2_empty_dir(inode)) {
 300                 err = ext2_unlink(dir, dentry);
 301                 if (!err) {
 302                         inode->i_size = 0;
 303                         inode_dec_link_count(inode);
 304                         inode_dec_link_count(dir);
 305                 }
 306         }
 307         return err;
 308 }
 309
 310 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 311         struct inode * new_dir, struct dentry * new_dentry )
 312 {
 313         struct inode * old_inode = old_dentry->d_inode;
 314         struct inode * new_inode = new_dentry->d_inode;
 315         struct page * dir_page = NULL;
 316         struct ext2_dir_entry_2 * dir_de = NULL;
 317         struct page * old_page;
 318         struct ext2_dir_entry_2 * old_de;
 319         int err = -ENOENT;
 320
 321         dquot_initialize(old_dir);
 322         dquot_initialize(new_dir);
 323
 324         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 325         if (!old_de)
 326                 goto out;
 327
 328         if (S_ISDIR(old_inode->i_mode)) {
 329                 err = -EIO;
 330                 dir_de = ext2_dotdot(old_inode, &dir_page);
 331                 if (!dir_de)
 332                         goto out_old;
 333         }
 334
 335         if (new_inode) {
 336                 struct page *new_page;
 337                 struct ext2_dir_entry_2 *new_de;
 338
 339                 err = -ENOTEMPTY;
 340                 if (dir_de && !ext2_empty_dir (new_inode))
 341                         goto out_dir;
 342
 343                 err = -ENOENT;
 344                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 345                 if (!new_de)
 346                         goto out_dir;
 347                 inode_inc_link_count(old_inode);
 348                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 349                 new_inode->i_ctime = CURRENT_TIME_SEC;
 350                 if (dir_de)
 351                         drop_nlink(new_inode);
 352                 inode_dec_link_count(new_inode);
 353         } else {
 354                 if (dir_de) {
 355                         err = -EMLINK;
 356                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 357                                 goto out_dir;
 358                 }
 359                 inode_inc_link_count(old_inode);
 360                 err = ext2_add_link(new_dentry, old_inode);
 361                 if (err) {
 362                         inode_dec_link_count(old_inode);
 363                         goto out_dir;
 364                 }
 365                 if (dir_de)
 366                         inode_inc_link_count(new_dir);
 367         }
 368
 369         /*
 370          * Like most other Unix systems, set the ctime for inodes on a
 371          * rename.
 372          * inode_dec_link_count() will mark the inode dirty.
 373          */
 374         old_inode->i_ctime = CURRENT_TIME_SEC;
 375
 376         ext2_delete_entry (old_de, old_page);
 377         inode_dec_link_count(old_inode);
 378
 379         if (dir_de) {
 380                 if (old_dir != new_dir)
 381                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 382                 else {
 383                         kunmap(dir_page);
 384                         page_cache_release(dir_page);
 385                 }
 386                 inode_dec_link_count(old_dir);
 387         }
 388         return 0;
 389
 390
 391 out_dir:
 392         if (dir_de) {
 393                 kunmap(dir_page);
 394                 page_cache_release(dir_page);
 395         }
 396 out_old:
 397         kunmap(old_page);
 398         page_cache_release(old_page);
 399 out:
 400         return err;
 401 }
 402
 403 const struct inode_operations ext2_dir_inode_operations = {
 404         .create         = ext2_create,
 405         .lookup         = ext2_lookup,
 406         .link           = ext2_link,
 407         .unlink         = ext2_unlink,
 408         .symlink        = ext2_symlink,
 409         .mkdir          = ext2_mkdir,
 410         .rmdir          = ext2_rmdir,
 411         .mknod          = ext2_mknod,
 412         .rename         = ext2_rename,
 413 #ifdef CONFIG_EXT2_FS_XATTR
 414         .setxattr       = generic_setxattr,
 415         .getxattr       = generic_getxattr,
 416         .listxattr      = ext2_listxattr,
 417         .removexattr    = generic_removexattr,
 418 #endif
 419         .setattr        = ext2_setattr,
 420         .check_acl      = ext2_check_acl,
 421 };
 422
 423 const struct inode_operations ext2_special_inode_operations = {
 424 #ifdef CONFIG_EXT2_FS_XATTR
 425         .setxattr       = generic_setxattr,
 426         .getxattr       = generic_getxattr,
 427         .listxattr      = ext2_listxattr,
 428         .removexattr    = generic_removexattr,
 429 #endif
 430         .setattr        = ext2_setattr,
 431         .check_acl      = ext2_check_acl,
 432 };