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                 d_instantiate_new(dentry, 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, unsigned int flags)
  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 (inode == ERR_PTR(-ESTALE)) {
  70                         ext2_error(dir->i_sb, __func__,
  71                                         "deleted inode referenced: %lu",
  72                                         (unsigned long) ino);
  73                         return ERR_PTR(-EIO);
  74                 }
  75         }
  76         return d_splice_alias(inode, dentry);
  77 }
  78
  79 struct dentry *ext2_get_parent(struct dentry *child)
  80 {
  81         struct qstr dotdot = QSTR_INIT("..", 2);
  82         unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
  83         if (!ino)
  84                 return ERR_PTR(-ENOENT);
  85         return d_obtain_alias(ext2_iget(child->d_sb, ino));
  86 }
  87
  88 /*
  89  * By the time this is called, we already have created
  90  * the directory cache entry for the new file, but it
  91  * is so far negative - it has no inode.
  92  *
  93  * If the create succeeds, we fill in the inode information
  94  * with d_instantiate().
  95  */
  96 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
  97 {
  98         struct inode *inode;
  99         int err;
 100
 101         err = dquot_initialize(dir);
 102         if (err)
 103                 return err;
 104
 105         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 106         if (IS_ERR(inode))
 107                 return PTR_ERR(inode);
 108
 109         inode->i_op = &ext2_file_inode_operations;
 110         if (test_opt(inode->i_sb, NOBH)) {
 111                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 112                 inode->i_fop = &ext2_file_operations;
 113         } else {
 114                 inode->i_mapping->a_ops = &ext2_aops;
 115                 inode->i_fop = &ext2_file_operations;
 116         }
 117         mark_inode_dirty(inode);
 118         return ext2_add_nondir(dentry, inode);
 119 }
 120
 121 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 122 {
 123         struct inode *inode = ext2_new_inode(dir, mode, NULL);
 124         if (IS_ERR(inode))
 125                 return PTR_ERR(inode);
 126
 127         inode->i_op = &ext2_file_inode_operations;
 128         if (test_opt(inode->i_sb, NOBH)) {
 129                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 130                 inode->i_fop = &ext2_file_operations;
 131         } else {
 132                 inode->i_mapping->a_ops = &ext2_aops;
 133                 inode->i_fop = &ext2_file_operations;
 134         }
 135         mark_inode_dirty(inode);
 136         d_tmpfile(dentry, inode);
 137         unlock_new_inode(inode);
 138         return 0;
 139 }
 140
 141 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 142 {
 143         struct inode * inode;
 144         int err;
 145
 146         err = dquot_initialize(dir);
 147         if (err)
 148                 return err;
 149
 150         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 151         err = PTR_ERR(inode);
 152         if (!IS_ERR(inode)) {
 153                 init_special_inode(inode, inode->i_mode, rdev);
 154 #ifdef CONFIG_EXT2_FS_XATTR
 155                 inode->i_op = &ext2_special_inode_operations;
 156 #endif
 157                 mark_inode_dirty(inode);
 158                 err = ext2_add_nondir(dentry, inode);
 159         }
 160         return err;
 161 }
 162
 163 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 164         const char * symname)
 165 {
 166         struct super_block * sb = dir->i_sb;
 167         int err = -ENAMETOOLONG;
 168         unsigned l = strlen(symname)+1;
 169         struct inode * inode;
 170
 171         if (l > sb->s_blocksize)
 172                 goto out;
 173
 174         err = dquot_initialize(dir);
 175         if (err)
 176                 goto out;
 177
 178         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 179         err = PTR_ERR(inode);
 180         if (IS_ERR(inode))
 181                 goto out;
 182
 183         if (l > sizeof (EXT2_I(inode)->i_data)) {
 184                 /* slow symlink */
 185                 inode->i_op = &ext2_symlink_inode_operations;
 186                 inode_nohighmem(inode);
 187                 if (test_opt(inode->i_sb, NOBH))
 188                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 189                 else
 190                         inode->i_mapping->a_ops = &ext2_aops;
 191                 err = page_symlink(inode, symname, l);
 192                 if (err)
 193                         goto out_fail;
 194         } else {
 195                 /* fast symlink */
 196                 inode->i_op = &ext2_fast_symlink_inode_operations;
 197                 inode->i_link = (char*)EXT2_I(inode)->i_data;
 198                 memcpy(inode->i_link, symname, l);
 199                 inode->i_size = l-1;
 200         }
 201         mark_inode_dirty(inode);
 202
 203         err = ext2_add_nondir(dentry, inode);
 204 out:
 205         return err;
 206
 207 out_fail:
 208         inode_dec_link_count(inode);
 209         unlock_new_inode(inode);
 210         iput (inode);
 211         goto out;
 212 }
 213
 214 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 215         struct dentry *dentry)
 216 {
 217         struct inode *inode = d_inode(old_dentry);
 218         int err;
 219
 220         err = dquot_initialize(dir);
 221         if (err)
 222                 return err;
 223
 224         inode->i_ctime = current_time(inode);
 225         inode_inc_link_count(inode);
 226         ihold(inode);
 227
 228         err = ext2_add_link(dentry, inode);
 229         if (!err) {
 230                 d_instantiate(dentry, inode);
 231                 return 0;
 232         }
 233         inode_dec_link_count(inode);
 234         iput(inode);
 235         return err;
 236 }
 237
 238 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 239 {
 240         struct inode * inode;
 241         int err;
 242
 243         err = dquot_initialize(dir);
 244         if (err)
 245                 return err;
 246
 247         inode_inc_link_count(dir);
 248
 249         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 250         err = PTR_ERR(inode);
 251         if (IS_ERR(inode))
 252                 goto out_dir;
 253
 254         inode->i_op = &ext2_dir_inode_operations;
 255         inode->i_fop = &ext2_dir_operations;
 256         if (test_opt(inode->i_sb, NOBH))
 257                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 258         else
 259                 inode->i_mapping->a_ops = &ext2_aops;
 260
 261         inode_inc_link_count(inode);
 262
 263         err = ext2_make_empty(inode, dir);
 264         if (err)
 265                 goto out_fail;
 266
 267         err = ext2_add_link(dentry, inode);
 268         if (err)
 269                 goto out_fail;
 270
 271         d_instantiate_new(dentry, inode);
 272 out:
 273         return err;
 274
 275 out_fail:
 276         inode_dec_link_count(inode);
 277         inode_dec_link_count(inode);
 278         unlock_new_inode(inode);
 279         iput(inode);
 280 out_dir:
 281         inode_dec_link_count(dir);
 282         goto out;
 283 }
 284
 285 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 286 {
 287         struct inode * inode = d_inode(dentry);
 288         struct ext2_dir_entry_2 * de;
 289         struct page * page;
 290         int err;
 291
 292         err = dquot_initialize(dir);
 293         if (err)
 294                 goto out;
 295
 296         de = ext2_find_entry (dir, &dentry->d_name, &page);
 297         if (!de) {
 298                 err = -ENOENT;
 299                 goto out;
 300         }
 301
 302         err = ext2_delete_entry (de, page);
 303         if (err)
 304                 goto out;
 305
 306         inode->i_ctime = dir->i_ctime;
 307         inode_dec_link_count(inode);
 308         err = 0;
 309 out:
 310         return err;
 311 }
 312
 313 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 314 {
 315         struct inode * inode = d_inode(dentry);
 316         int err = -ENOTEMPTY;
 317
 318         if (ext2_empty_dir(inode)) {
 319                 err = ext2_unlink(dir, dentry);
 320                 if (!err) {
 321                         inode->i_size = 0;
 322                         inode_dec_link_count(inode);
 323                         inode_dec_link_count(dir);
 324                 }
 325         }
 326         return err;
 327 }
 328
 329 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 330                         struct inode * new_dir, struct dentry * new_dentry,
 331                         unsigned int flags)
 332 {
 333         struct inode * old_inode = d_inode(old_dentry);
 334         struct inode * new_inode = d_inode(new_dentry);
 335         struct page * dir_page = NULL;
 336         struct ext2_dir_entry_2 * dir_de = NULL;
 337         struct page * old_page;
 338         struct ext2_dir_entry_2 * old_de;
 339         int err;
 340
 341         if (flags & ~RENAME_NOREPLACE)
 342                 return -EINVAL;
 343
 344         err = dquot_initialize(old_dir);
 345         if (err)
 346                 goto out;
 347
 348         err = dquot_initialize(new_dir);
 349         if (err)
 350                 goto out;
 351
 352         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 353         if (!old_de) {
 354                 err = -ENOENT;
 355                 goto out;
 356         }
 357
 358         if (S_ISDIR(old_inode->i_mode)) {
 359                 err = -EIO;
 360                 dir_de = ext2_dotdot(old_inode, &dir_page);
 361                 if (!dir_de)
 362                         goto out_old;
 363         }
 364
 365         if (new_inode) {
 366                 struct page *new_page;
 367                 struct ext2_dir_entry_2 *new_de;
 368
 369                 err = -ENOTEMPTY;
 370                 if (dir_de && !ext2_empty_dir (new_inode))
 371                         goto out_dir;
 372
 373                 err = -ENOENT;
 374                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 375                 if (!new_de)
 376                         goto out_dir;
 377                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 378                 new_inode->i_ctime = current_time(new_inode);
 379                 if (dir_de)
 380                         drop_nlink(new_inode);
 381                 inode_dec_link_count(new_inode);
 382         } else {
 383                 err = ext2_add_link(new_dentry, old_inode);
 384                 if (err)
 385                         goto out_dir;
 386                 if (dir_de)
 387                         inode_inc_link_count(new_dir);
 388         }
 389
 390         /*
 391          * Like most other Unix systems, set the ctime for inodes on a
 392          * rename.
 393          */
 394         old_inode->i_ctime = current_time(old_inode);
 395         mark_inode_dirty(old_inode);
 396
 397         ext2_delete_entry (old_de, old_page);
 398
 399         if (dir_de) {
 400                 if (old_dir != new_dir)
 401                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 402                 else {
 403                         kunmap(dir_page);
 404                         put_page(dir_page);
 405                 }
 406                 inode_dec_link_count(old_dir);
 407         }
 408         return 0;
 409
 410
 411 out_dir:
 412         if (dir_de) {
 413                 kunmap(dir_page);
 414                 put_page(dir_page);
 415         }
 416 out_old:
 417         kunmap(old_page);
 418         put_page(old_page);
 419 out:
 420         return err;
 421 }
 422
 423 const struct inode_operations ext2_dir_inode_operations = {
 424         .create         = ext2_create,
 425         .lookup         = ext2_lookup,
 426         .link           = ext2_link,
 427         .unlink         = ext2_unlink,
 428         .symlink        = ext2_symlink,
 429         .mkdir          = ext2_mkdir,
 430         .rmdir          = ext2_rmdir,
 431         .mknod          = ext2_mknod,
 432         .rename         = ext2_rename,
 433 #ifdef CONFIG_EXT2_FS_XATTR
 434         .listxattr      = ext2_listxattr,
 435 #endif
 436         .setattr        = ext2_setattr,
 437         .get_acl        = ext2_get_acl,
 438         .set_acl        = ext2_set_acl,
 439         .tmpfile        = ext2_tmpfile,
 440 };
 441
 442 const struct inode_operations ext2_special_inode_operations = {
 443 #ifdef CONFIG_EXT2_FS_XATTR
 444         .listxattr      = ext2_listxattr,
 445 #endif
 446         .setattr        = ext2_setattr,
 447         .get_acl        = ext2_get_acl,
 448         .set_acl        = ext2_set_acl,
 449 };