fs/ext2/namei.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/ext2/namei.c
   4  *
   5  * Rewrite to pagecache. Almost all code had been changed, so blame me
   6  * if the things go wrong. Please, send bug reports to
   7  * viro@parcelfarce.linux.theplanet.co.uk
   8  *
   9  * Stuff here is basically a glue between the VFS and generic UNIXish
  10  * filesystem that keeps everything in pagecache. All knowledge of the
  11  * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
  12  * and it's easier to debug that way. In principle we might want to
  13  * generalize that a bit and turn it into a library. Or not.
  14  *
  15  * The only non-static object here is ext2_dir_inode_operations.
  16  *
  17  * TODO: get rid of kmap() use, add readahead.
  18  *
  19  * Copyright (C) 1992, 1993, 1994, 1995
  20  * Remy Card (card@masi.ibp.fr)
  21  * Laboratoire MASI - Institut Blaise Pascal
  22  * Universite Pierre et Marie Curie (Paris VI)
  23  *
  24  *  from
  25  *
  26  *  linux/fs/minix/namei.c
  27  *
  28  *  Copyright (C) 1991, 1992  Linus Torvalds
  29  *
  30  *  Big-endian to little-endian byte-swapping/bitmaps by
  31  *        David S. Miller (davem@caip.rutgers.edu), 1995
  32  */
  33
  34 #include <linux/pagemap.h>
  35 #include <linux/quotaops.h>
  36 #include "ext2.h"
  37 #include "xattr.h"
  38 #include "acl.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                 unlock_new_inode(inode);
  45                 d_instantiate(dentry, 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, unsigned int flags)
  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 (inode == ERR_PTR(-ESTALE)) {
  71                         ext2_error(dir->i_sb, __func__,
  72                                         "deleted inode referenced: %lu",
  73                                         (unsigned long) ino);
  74                         return ERR_PTR(-EIO);
  75                 }
  76         }
  77         return d_splice_alias(inode, dentry);
  78 }
  79
  80 struct dentry *ext2_get_parent(struct dentry *child)
  81 {
  82         struct qstr dotdot = QSTR_INIT("..", 2);
  83         unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
  84         if (!ino)
  85                 return ERR_PTR(-ENOENT);
  86         return d_obtain_alias(ext2_iget(child->d_sb, ino));
  87 }
  88
  89 /*
  90  * By the time this is called, we already have created
  91  * the directory cache entry for the new file, but it
  92  * is so far negative - it has no inode.
  93  *
  94  * If the create succeeds, we fill in the inode information
  95  * with d_instantiate().
  96  */
  97 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
  98 {
  99         struct inode *inode;
 100         int err;
 101
 102         err = dquot_initialize(dir);
 103         if (err)
 104                 return err;
 105
 106         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 107         if (IS_ERR(inode))
 108                 return PTR_ERR(inode);
 109
 110         inode->i_op = &ext2_file_inode_operations;
 111         if (test_opt(inode->i_sb, NOBH)) {
 112                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 113                 inode->i_fop = &ext2_file_operations;
 114         } else {
 115                 inode->i_mapping->a_ops = &ext2_aops;
 116                 inode->i_fop = &ext2_file_operations;
 117         }
 118         mark_inode_dirty(inode);
 119         return ext2_add_nondir(dentry, inode);
 120 }
 121
 122 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 123 {
 124         struct inode *inode = ext2_new_inode(dir, mode, NULL);
 125         if (IS_ERR(inode))
 126                 return PTR_ERR(inode);
 127
 128         inode->i_op = &ext2_file_inode_operations;
 129         if (test_opt(inode->i_sb, NOBH)) {
 130                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 131                 inode->i_fop = &ext2_file_operations;
 132         } else {
 133                 inode->i_mapping->a_ops = &ext2_aops;
 134                 inode->i_fop = &ext2_file_operations;
 135         }
 136         mark_inode_dirty(inode);
 137         d_tmpfile(dentry, inode);
 138         unlock_new_inode(inode);
 139         return 0;
 140 }
 141
 142 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 143 {
 144         struct inode * inode;
 145         int err;
 146
 147         err = dquot_initialize(dir);
 148         if (err)
 149                 return err;
 150
 151         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 152         err = PTR_ERR(inode);
 153         if (!IS_ERR(inode)) {
 154                 init_special_inode(inode, inode->i_mode, rdev);
 155 #ifdef CONFIG_EXT2_FS_XATTR
 156                 inode->i_op = &ext2_special_inode_operations;
 157 #endif
 158                 mark_inode_dirty(inode);
 159                 err = ext2_add_nondir(dentry, inode);
 160         }
 161         return err;
 162 }
 163
 164 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 165         const char * symname)
 166 {
 167         struct super_block * sb = dir->i_sb;
 168         int err = -ENAMETOOLONG;
 169         unsigned l = strlen(symname)+1;
 170         struct inode * inode;
 171
 172         if (l > sb->s_blocksize)
 173                 goto out;
 174
 175         err = dquot_initialize(dir);
 176         if (err)
 177                 goto out;
 178
 179         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 180         err = PTR_ERR(inode);
 181         if (IS_ERR(inode))
 182                 goto out;
 183
 184         if (l > sizeof (EXT2_I(inode)->i_data)) {
 185                 /* slow symlink */
 186                 inode->i_op = &ext2_symlink_inode_operations;
 187                 inode_nohighmem(inode);
 188                 if (test_opt(inode->i_sb, NOBH))
 189                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 190                 else
 191                         inode->i_mapping->a_ops = &ext2_aops;
 192                 err = page_symlink(inode, symname, l);
 193                 if (err)
 194                         goto out_fail;
 195         } else {
 196                 /* fast symlink */
 197                 inode->i_op = &ext2_fast_symlink_inode_operations;
 198                 inode->i_link = (char*)EXT2_I(inode)->i_data;
 199                 memcpy(inode->i_link, symname, l);
 200                 inode->i_size = l-1;
 201         }
 202         mark_inode_dirty(inode);
 203
 204         err = ext2_add_nondir(dentry, inode);
 205 out:
 206         return err;
 207
 208 out_fail:
 209         inode_dec_link_count(inode);
 210         unlock_new_inode(inode);
 211         iput (inode);
 212         goto out;
 213 }
 214
 215 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 216         struct dentry *dentry)
 217 {
 218         struct inode *inode = d_inode(old_dentry);
 219         int err;
 220
 221         err = dquot_initialize(dir);
 222         if (err)
 223                 return err;
 224
 225         inode->i_ctime = current_time(inode);
 226         inode_inc_link_count(inode);
 227         ihold(inode);
 228
 229         err = ext2_add_link(dentry, inode);
 230         if (!err) {
 231                 d_instantiate(dentry, inode);
 232                 return 0;
 233         }
 234         inode_dec_link_count(inode);
 235         iput(inode);
 236         return err;
 237 }
 238
 239 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 240 {
 241         struct inode * inode;
 242         int err;
 243
 244         err = dquot_initialize(dir);
 245         if (err)
 246                 return err;
 247
 248         inode_inc_link_count(dir);
 249
 250         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 251         err = PTR_ERR(inode);
 252         if (IS_ERR(inode))
 253                 goto out_dir;
 254
 255         inode->i_op = &ext2_dir_inode_operations;
 256         inode->i_fop = &ext2_dir_operations;
 257         if (test_opt(inode->i_sb, NOBH))
 258                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 259         else
 260                 inode->i_mapping->a_ops = &ext2_aops;
 261
 262         inode_inc_link_count(inode);
 263
 264         err = ext2_make_empty(inode, dir);
 265         if (err)
 266                 goto out_fail;
 267
 268         err = ext2_add_link(dentry, inode);
 269         if (err)
 270                 goto out_fail;
 271
 272         unlock_new_inode(inode);
 273         d_instantiate(dentry, inode);
 274 out:
 275         return err;
 276
 277 out_fail:
 278         inode_dec_link_count(inode);
 279         inode_dec_link_count(inode);
 280         unlock_new_inode(inode);
 281         iput(inode);
 282 out_dir:
 283         inode_dec_link_count(dir);
 284         goto out;
 285 }
 286
 287 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 288 {
 289         struct inode * inode = d_inode(dentry);
 290         struct ext2_dir_entry_2 * de;
 291         struct page * page;
 292         int err;
 293
 294         err = dquot_initialize(dir);
 295         if (err)
 296                 goto out;
 297
 298         de = ext2_find_entry (dir, &dentry->d_name, &page);
 299         if (!de) {
 300                 err = -ENOENT;
 301                 goto out;
 302         }
 303
 304         err = ext2_delete_entry (de, page);
 305         if (err)
 306                 goto out;
 307
 308         inode->i_ctime = dir->i_ctime;
 309         inode_dec_link_count(inode);
 310         err = 0;
 311 out:
 312         return err;
 313 }
 314
 315 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 316 {
 317         struct inode * inode = d_inode(dentry);
 318         int err = -ENOTEMPTY;
 319
 320         if (ext2_empty_dir(inode)) {
 321                 err = ext2_unlink(dir, dentry);
 322                 if (!err) {
 323                         inode->i_size = 0;
 324                         inode_dec_link_count(inode);
 325                         inode_dec_link_count(dir);
 326                 }
 327         }
 328         return err;
 329 }
 330
 331 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 332                         struct inode * new_dir, struct dentry * new_dentry,
 333                         unsigned int flags)
 334 {
 335         struct inode * old_inode = d_inode(old_dentry);
 336         struct inode * new_inode = d_inode(new_dentry);
 337         struct page * dir_page = NULL;
 338         struct ext2_dir_entry_2 * dir_de = NULL;
 339         struct page * old_page;
 340         struct ext2_dir_entry_2 * old_de;
 341         int err;
 342
 343         if (flags & ~RENAME_NOREPLACE)
 344                 return -EINVAL;
 345
 346         err = dquot_initialize(old_dir);
 347         if (err)
 348                 goto out;
 349
 350         err = dquot_initialize(new_dir);
 351         if (err)
 352                 goto out;
 353
 354         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 355         if (!old_de) {
 356                 err = -ENOENT;
 357                 goto out;
 358         }
 359
 360         if (S_ISDIR(old_inode->i_mode)) {
 361                 err = -EIO;
 362                 dir_de = ext2_dotdot(old_inode, &dir_page);
 363                 if (!dir_de)
 364                         goto out_old;
 365         }
 366
 367         if (new_inode) {
 368                 struct page *new_page;
 369                 struct ext2_dir_entry_2 *new_de;
 370
 371                 err = -ENOTEMPTY;
 372                 if (dir_de && !ext2_empty_dir (new_inode))
 373                         goto out_dir;
 374
 375                 err = -ENOENT;
 376                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 377                 if (!new_de)
 378                         goto out_dir;
 379                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 380                 new_inode->i_ctime = current_time(new_inode);
 381                 if (dir_de)
 382                         drop_nlink(new_inode);
 383                 inode_dec_link_count(new_inode);
 384         } else {
 385                 err = ext2_add_link(new_dentry, old_inode);
 386                 if (err)
 387                         goto out_dir;
 388                 if (dir_de)
 389                         inode_inc_link_count(new_dir);
 390         }
 391
 392         /*
 393          * Like most other Unix systems, set the ctime for inodes on a
 394          * rename.
 395          */
 396         old_inode->i_ctime = current_time(old_inode);
 397         mark_inode_dirty(old_inode);
 398
 399         ext2_delete_entry (old_de, old_page);
 400
 401         if (dir_de) {
 402                 if (old_dir != new_dir)
 403                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 404                 else {
 405                         kunmap(dir_page);
 406                         put_page(dir_page);
 407                 }
 408                 inode_dec_link_count(old_dir);
 409         }
 410         return 0;
 411
 412
 413 out_dir:
 414         if (dir_de) {
 415                 kunmap(dir_page);
 416                 put_page(dir_page);
 417         }
 418 out_old:
 419         kunmap(old_page);
 420         put_page(old_page);
 421 out:
 422         return err;
 423 }
 424
 425 const struct inode_operations ext2_dir_inode_operations = {
 426         .create         = ext2_create,
 427         .lookup         = ext2_lookup,
 428         .link           = ext2_link,
 429         .unlink         = ext2_unlink,
 430         .symlink        = ext2_symlink,
 431         .mkdir          = ext2_mkdir,
 432         .rmdir          = ext2_rmdir,
 433         .mknod          = ext2_mknod,
 434         .rename         = ext2_rename,
 435 #ifdef CONFIG_EXT2_FS_XATTR
 436         .listxattr      = ext2_listxattr,
 437 #endif
 438         .setattr        = ext2_setattr,
 439         .get_acl        = ext2_get_acl,
 440         .set_acl        = ext2_set_acl,
 441         .tmpfile        = ext2_tmpfile,
 442 };
 443
 444 const struct inode_operations ext2_special_inode_operations = {
 445 #ifdef CONFIG_EXT2_FS_XATTR
 446         .listxattr      = ext2_listxattr,
 447 #endif
 448         .setattr        = ext2_setattr,
 449         .get_acl        = ext2_get_acl,
 450         .set_acl        = ext2_set_acl,
 451 };