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         discard_new_inode(inode);
  49         return err;
  50 }
  51
  52 /*
  53  * Methods themselves.
  54  */
  55
  56 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
  57 {
  58         struct inode * inode;
  59         ino_t ino;
  60
  61         if (dentry->d_name.len > EXT2_NAME_LEN)
  62                 return ERR_PTR(-ENAMETOOLONG);
  63
  64         ino = ext2_inode_by_name(dir, &dentry->d_name);
  65         inode = NULL;
  66         if (ino) {
  67                 inode = ext2_iget(dir->i_sb, ino);
  68                 if (inode == ERR_PTR(-ESTALE)) {
  69                         ext2_error(dir->i_sb, __func__,
  70                                         "deleted inode referenced: %lu",
  71                                         (unsigned long) ino);
  72                         return ERR_PTR(-EIO);
  73                 }
  74         }
  75         return d_splice_alias(inode, dentry);
  76 }
  77
  78 struct dentry *ext2_get_parent(struct dentry *child)
  79 {
  80         struct qstr dotdot = QSTR_INIT("..", 2);
  81         unsigned long ino = ext2_inode_by_name(d_inode(child), &dotdot);
  82         if (!ino)
  83                 return ERR_PTR(-ENOENT);
  84         return d_obtain_alias(ext2_iget(child->d_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, umode_t mode, bool excl)
  96 {
  97         struct inode *inode;
  98         int err;
  99
 100         err = dquot_initialize(dir);
 101         if (err)
 102                 return err;
 103
 104         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 105         if (IS_ERR(inode))
 106                 return PTR_ERR(inode);
 107
 108         ext2_set_file_ops(inode);
 109         mark_inode_dirty(inode);
 110         return ext2_add_nondir(dentry, inode);
 111 }
 112
 113 static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 114 {
 115         struct inode *inode = ext2_new_inode(dir, mode, NULL);
 116         if (IS_ERR(inode))
 117                 return PTR_ERR(inode);
 118
 119         ext2_set_file_ops(inode);
 120         mark_inode_dirty(inode);
 121         d_tmpfile(dentry, inode);
 122         unlock_new_inode(inode);
 123         return 0;
 124 }
 125
 126 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 127 {
 128         struct inode * inode;
 129         int err;
 130
 131         err = dquot_initialize(dir);
 132         if (err)
 133                 return err;
 134
 135         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 136         err = PTR_ERR(inode);
 137         if (!IS_ERR(inode)) {
 138                 init_special_inode(inode, inode->i_mode, rdev);
 139 #ifdef CONFIG_EXT2_FS_XATTR
 140                 inode->i_op = &ext2_special_inode_operations;
 141 #endif
 142                 mark_inode_dirty(inode);
 143                 err = ext2_add_nondir(dentry, inode);
 144         }
 145         return err;
 146 }
 147
 148 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 149         const char * symname)
 150 {
 151         struct super_block * sb = dir->i_sb;
 152         int err = -ENAMETOOLONG;
 153         unsigned l = strlen(symname)+1;
 154         struct inode * inode;
 155
 156         if (l > sb->s_blocksize)
 157                 goto out;
 158
 159         err = dquot_initialize(dir);
 160         if (err)
 161                 goto out;
 162
 163         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 164         err = PTR_ERR(inode);
 165         if (IS_ERR(inode))
 166                 goto out;
 167
 168         if (l > sizeof (EXT2_I(inode)->i_data)) {
 169                 /* slow symlink */
 170                 inode->i_op = &ext2_symlink_inode_operations;
 171                 inode_nohighmem(inode);
 172                 if (test_opt(inode->i_sb, NOBH))
 173                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 174                 else
 175                         inode->i_mapping->a_ops = &ext2_aops;
 176                 err = page_symlink(inode, symname, l);
 177                 if (err)
 178                         goto out_fail;
 179         } else {
 180                 /* fast symlink */
 181                 inode->i_op = &ext2_fast_symlink_inode_operations;
 182                 inode->i_link = (char*)EXT2_I(inode)->i_data;
 183                 memcpy(inode->i_link, symname, l);
 184                 inode->i_size = l-1;
 185         }
 186         mark_inode_dirty(inode);
 187
 188         err = ext2_add_nondir(dentry, inode);
 189 out:
 190         return err;
 191
 192 out_fail:
 193         inode_dec_link_count(inode);
 194         discard_new_inode(inode);
 195         goto out;
 196 }
 197
 198 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 199         struct dentry *dentry)
 200 {
 201         struct inode *inode = d_inode(old_dentry);
 202         int err;
 203
 204         err = dquot_initialize(dir);
 205         if (err)
 206                 return err;
 207
 208         inode->i_ctime = current_time(inode);
 209         inode_inc_link_count(inode);
 210         ihold(inode);
 211
 212         err = ext2_add_link(dentry, inode);
 213         if (!err) {
 214                 d_instantiate(dentry, inode);
 215                 return 0;
 216         }
 217         inode_dec_link_count(inode);
 218         iput(inode);
 219         return err;
 220 }
 221
 222 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 223 {
 224         struct inode * inode;
 225         int err;
 226
 227         err = dquot_initialize(dir);
 228         if (err)
 229                 return err;
 230
 231         inode_inc_link_count(dir);
 232
 233         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 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_new(dentry, inode);
 256 out:
 257         return err;
 258
 259 out_fail:
 260         inode_dec_link_count(inode);
 261         inode_dec_link_count(inode);
 262         discard_new_inode(inode);
 263 out_dir:
 264         inode_dec_link_count(dir);
 265         goto out;
 266 }
 267
 268 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 269 {
 270         struct inode * inode = d_inode(dentry);
 271         struct ext2_dir_entry_2 * de;
 272         struct page * page;
 273         int err;
 274
 275         err = dquot_initialize(dir);
 276         if (err)
 277                 goto out;
 278
 279         de = ext2_find_entry (dir, &dentry->d_name, &page);
 280         if (!de) {
 281                 err = -ENOENT;
 282                 goto out;
 283         }
 284
 285         err = ext2_delete_entry (de, page);
 286         if (err)
 287                 goto out;
 288
 289         inode->i_ctime = dir->i_ctime;
 290         inode_dec_link_count(inode);
 291         err = 0;
 292 out:
 293         return err;
 294 }
 295
 296 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 297 {
 298         struct inode * inode = d_inode(dentry);
 299         int err = -ENOTEMPTY;
 300
 301         if (ext2_empty_dir(inode)) {
 302                 err = ext2_unlink(dir, dentry);
 303                 if (!err) {
 304                         inode->i_size = 0;
 305                         inode_dec_link_count(inode);
 306                         inode_dec_link_count(dir);
 307                 }
 308         }
 309         return err;
 310 }
 311
 312 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 313                         struct inode * new_dir, struct dentry * new_dentry,
 314                         unsigned int flags)
 315 {
 316         struct inode * old_inode = d_inode(old_dentry);
 317         struct inode * new_inode = d_inode(new_dentry);
 318         struct page * dir_page = NULL;
 319         struct ext2_dir_entry_2 * dir_de = NULL;
 320         struct page * old_page;
 321         struct ext2_dir_entry_2 * old_de;
 322         int err;
 323
 324         if (flags & ~RENAME_NOREPLACE)
 325                 return -EINVAL;
 326
 327         err = dquot_initialize(old_dir);
 328         if (err)
 329                 goto out;
 330
 331         err = dquot_initialize(new_dir);
 332         if (err)
 333                 goto out;
 334
 335         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 336         if (!old_de) {
 337                 err = -ENOENT;
 338                 goto out;
 339         }
 340
 341         if (S_ISDIR(old_inode->i_mode)) {
 342                 err = -EIO;
 343                 dir_de = ext2_dotdot(old_inode, &dir_page);
 344                 if (!dir_de)
 345                         goto out_old;
 346         }
 347
 348         if (new_inode) {
 349                 struct page *new_page;
 350                 struct ext2_dir_entry_2 *new_de;
 351
 352                 err = -ENOTEMPTY;
 353                 if (dir_de && !ext2_empty_dir (new_inode))
 354                         goto out_dir;
 355
 356                 err = -ENOENT;
 357                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 358                 if (!new_de)
 359                         goto out_dir;
 360                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 361                 new_inode->i_ctime = current_time(new_inode);
 362                 if (dir_de)
 363                         drop_nlink(new_inode);
 364                 inode_dec_link_count(new_inode);
 365         } else {
 366                 err = ext2_add_link(new_dentry, old_inode);
 367                 if (err)
 368                         goto out_dir;
 369                 if (dir_de)
 370                         inode_inc_link_count(new_dir);
 371         }
 372
 373         /*
 374          * Like most other Unix systems, set the ctime for inodes on a
 375          * rename.
 376          */
 377         old_inode->i_ctime = current_time(old_inode);
 378         mark_inode_dirty(old_inode);
 379
 380         ext2_delete_entry (old_de, old_page);
 381
 382         if (dir_de) {
 383                 if (old_dir != new_dir)
 384                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 385                 else {
 386                         kunmap(dir_page);
 387                         put_page(dir_page);
 388                 }
 389                 inode_dec_link_count(old_dir);
 390         }
 391         return 0;
 392
 393
 394 out_dir:
 395         if (dir_de) {
 396                 kunmap(dir_page);
 397                 put_page(dir_page);
 398         }
 399 out_old:
 400         kunmap(old_page);
 401         put_page(old_page);
 402 out:
 403         return err;
 404 }
 405
 406 const struct inode_operations ext2_dir_inode_operations = {
 407         .create         = ext2_create,
 408         .lookup         = ext2_lookup,
 409         .link           = ext2_link,
 410         .unlink         = ext2_unlink,
 411         .symlink        = ext2_symlink,
 412         .mkdir          = ext2_mkdir,
 413         .rmdir          = ext2_rmdir,
 414         .mknod          = ext2_mknod,
 415         .rename         = ext2_rename,
 416 #ifdef CONFIG_EXT2_FS_XATTR
 417         .listxattr      = ext2_listxattr,
 418 #endif
 419         .getattr        = ext2_getattr,
 420         .setattr        = ext2_setattr,
 421         .get_acl        = ext2_get_acl,
 422         .set_acl        = ext2_set_acl,
 423         .tmpfile        = ext2_tmpfile,
 424 };
 425
 426 const struct inode_operations ext2_special_inode_operations = {
 427 #ifdef CONFIG_EXT2_FS_XATTR
 428         .listxattr      = ext2_listxattr,
 429 #endif
 430         .getattr        = ext2_getattr,
 431         .setattr        = ext2_setattr,
 432         .get_acl        = ext2_get_acl,
 433         .set_acl        = ext2_set_acl,
 434 };