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         int res;
  61
  62         if (dentry->d_name.len > EXT2_NAME_LEN)
  63                 return ERR_PTR(-ENAMETOOLONG);
  64
  65         res = ext2_inode_by_name(dir, &dentry->d_name, &ino);
  66         if (res) {
  67                 if (res != -ENOENT)
  68                         return ERR_PTR(res);
  69                 inode = NULL;
  70         } else {
  71                 inode = ext2_iget(dir->i_sb, ino);
  72                 if (inode == ERR_PTR(-ESTALE)) {
  73                         ext2_error(dir->i_sb, __func__,
  74                                         "deleted inode referenced: %lu",
  75                                         (unsigned long) ino);
  76                         return ERR_PTR(-EIO);
  77                 }
  78         }
  79         return d_splice_alias(inode, dentry);
  80 }
  81
  82 struct dentry *ext2_get_parent(struct dentry *child)
  83 {
  84         ino_t ino;
  85         int res;
  86
  87         res = ext2_inode_by_name(d_inode(child), &dotdot_name, &ino);
  88         if (res)
  89                 return ERR_PTR(res);
  90
  91         return d_obtain_alias(ext2_iget(child->d_sb, ino));
  92 }
  93
  94 /*
  95  * By the time this is called, we already have created
  96  * the directory cache entry for the new file, but it
  97  * is so far negative - it has no inode.
  98  *
  99  * If the create succeeds, we fill in the inode information
 100  * with d_instantiate().
 101  */
 102 static int ext2_create (struct mnt_idmap * idmap,
 103                         struct inode * dir, struct dentry * dentry,
 104                         umode_t mode, bool excl)
 105 {
 106         struct inode *inode;
 107         int err;
 108
 109         err = dquot_initialize(dir);
 110         if (err)
 111                 return err;
 112
 113         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 114         if (IS_ERR(inode))
 115                 return PTR_ERR(inode);
 116
 117         ext2_set_file_ops(inode);
 118         mark_inode_dirty(inode);
 119         return ext2_add_nondir(dentry, inode);
 120 }
 121
 122 static int ext2_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
 123                         struct file *file, umode_t mode)
 124 {
 125         struct inode *inode = ext2_new_inode(dir, mode, NULL);
 126         if (IS_ERR(inode))
 127                 return PTR_ERR(inode);
 128
 129         ext2_set_file_ops(inode);
 130         mark_inode_dirty(inode);
 131         d_tmpfile(file, inode);
 132         unlock_new_inode(inode);
 133         return finish_open_simple(file, 0);
 134 }
 135
 136 static int ext2_mknod (struct mnt_idmap * idmap, struct inode * dir,
 137         struct dentry *dentry, umode_t mode, dev_t rdev)
 138 {
 139         struct inode * inode;
 140         int err;
 141
 142         err = dquot_initialize(dir);
 143         if (err)
 144                 return err;
 145
 146         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 147         err = PTR_ERR(inode);
 148         if (!IS_ERR(inode)) {
 149                 init_special_inode(inode, inode->i_mode, rdev);
 150                 inode->i_op = &ext2_special_inode_operations;
 151                 mark_inode_dirty(inode);
 152                 err = ext2_add_nondir(dentry, inode);
 153         }
 154         return err;
 155 }
 156
 157 static int ext2_symlink (struct mnt_idmap * idmap, struct inode * dir,
 158         struct dentry * dentry, const char * symname)
 159 {
 160         struct super_block * sb = dir->i_sb;
 161         int err = -ENAMETOOLONG;
 162         unsigned l = strlen(symname)+1;
 163         struct inode * inode;
 164
 165         if (l > sb->s_blocksize)
 166                 goto out;
 167
 168         err = dquot_initialize(dir);
 169         if (err)
 170                 goto out;
 171
 172         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 173         err = PTR_ERR(inode);
 174         if (IS_ERR(inode))
 175                 goto out;
 176
 177         if (l > sizeof (EXT2_I(inode)->i_data)) {
 178                 /* slow symlink */
 179                 inode->i_op = &ext2_symlink_inode_operations;
 180                 inode_nohighmem(inode);
 181                 inode->i_mapping->a_ops = &ext2_aops;
 182                 err = page_symlink(inode, symname, l);
 183                 if (err)
 184                         goto out_fail;
 185         } else {
 186                 /* fast symlink */
 187                 inode->i_op = &ext2_fast_symlink_inode_operations;
 188                 inode->i_link = (char*)EXT2_I(inode)->i_data;
 189                 memcpy(inode->i_link, symname, l);
 190                 inode->i_size = l-1;
 191         }
 192         mark_inode_dirty(inode);
 193
 194         err = ext2_add_nondir(dentry, inode);
 195 out:
 196         return err;
 197
 198 out_fail:
 199         inode_dec_link_count(inode);
 200         discard_new_inode(inode);
 201         goto out;
 202 }
 203
 204 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 205         struct dentry *dentry)
 206 {
 207         struct inode *inode = d_inode(old_dentry);
 208         int err;
 209
 210         err = dquot_initialize(dir);
 211         if (err)
 212                 return err;
 213
 214         inode_set_ctime_current(inode);
 215         inode_inc_link_count(inode);
 216         ihold(inode);
 217
 218         err = ext2_add_link(dentry, inode);
 219         if (!err) {
 220                 d_instantiate(dentry, inode);
 221                 return 0;
 222         }
 223         inode_dec_link_count(inode);
 224         iput(inode);
 225         return err;
 226 }
 227
 228 static int ext2_mkdir(struct mnt_idmap * idmap,
 229         struct inode * dir, struct dentry * dentry, umode_t mode)
 230 {
 231         struct inode * inode;
 232         int err;
 233
 234         err = dquot_initialize(dir);
 235         if (err)
 236                 return err;
 237
 238         inode_inc_link_count(dir);
 239
 240         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 241         err = PTR_ERR(inode);
 242         if (IS_ERR(inode))
 243                 goto out_dir;
 244
 245         inode->i_op = &ext2_dir_inode_operations;
 246         inode->i_fop = &ext2_dir_operations;
 247         inode->i_mapping->a_ops = &ext2_aops;
 248
 249         inode_inc_link_count(inode);
 250
 251         err = ext2_make_empty(inode, dir);
 252         if (err)
 253                 goto out_fail;
 254
 255         err = ext2_add_link(dentry, inode);
 256         if (err)
 257                 goto out_fail;
 258
 259         d_instantiate_new(dentry, inode);
 260 out:
 261         return err;
 262
 263 out_fail:
 264         inode_dec_link_count(inode);
 265         inode_dec_link_count(inode);
 266         discard_new_inode(inode);
 267 out_dir:
 268         inode_dec_link_count(dir);
 269         goto out;
 270 }
 271
 272 static int ext2_unlink(struct inode *dir, struct dentry *dentry)
 273 {
 274         struct inode *inode = d_inode(dentry);
 275         struct ext2_dir_entry_2 *de;
 276         struct folio *folio;
 277         int err;
 278
 279         err = dquot_initialize(dir);
 280         if (err)
 281                 goto out;
 282
 283         de = ext2_find_entry(dir, &dentry->d_name, &folio);
 284         if (IS_ERR(de)) {
 285                 err = PTR_ERR(de);
 286                 goto out;
 287         }
 288
 289         err = ext2_delete_entry(de, folio);
 290         folio_release_kmap(folio, de);
 291         if (err)
 292                 goto out;
 293
 294         inode_set_ctime_to_ts(inode, inode_get_ctime(dir));
 295         inode_dec_link_count(inode);
 296         err = 0;
 297 out:
 298         return err;
 299 }
 300
 301 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 302 {
 303         struct inode * inode = d_inode(dentry);
 304         int err = -ENOTEMPTY;
 305
 306         if (ext2_empty_dir(inode)) {
 307                 err = ext2_unlink(dir, dentry);
 308                 if (!err) {
 309                         inode->i_size = 0;
 310                         inode_dec_link_count(inode);
 311                         inode_dec_link_count(dir);
 312                 }
 313         }
 314         return err;
 315 }
 316
 317 static int ext2_rename (struct mnt_idmap * idmap,
 318                         struct inode * old_dir, struct dentry * old_dentry,
 319                         struct inode * new_dir, struct dentry * new_dentry,
 320                         unsigned int flags)
 321 {
 322         struct inode * old_inode = d_inode(old_dentry);
 323         struct inode * new_inode = d_inode(new_dentry);
 324         struct folio *dir_folio = NULL;
 325         struct ext2_dir_entry_2 * dir_de = NULL;
 326         struct folio * old_folio;
 327         struct ext2_dir_entry_2 * old_de;
 328         bool old_is_dir = S_ISDIR(old_inode->i_mode);
 329         int err;
 330
 331         if (flags & ~RENAME_NOREPLACE)
 332                 return -EINVAL;
 333
 334         err = dquot_initialize(old_dir);
 335         if (err)
 336                 return err;
 337
 338         err = dquot_initialize(new_dir);
 339         if (err)
 340                 return err;
 341
 342         old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_folio);
 343         if (IS_ERR(old_de))
 344                 return PTR_ERR(old_de);
 345
 346         if (old_is_dir && old_dir != new_dir) {
 347                 err = -EIO;
 348                 dir_de = ext2_dotdot(old_inode, &dir_folio);
 349                 if (!dir_de)
 350                         goto out_old;
 351         }
 352
 353         if (new_inode) {
 354                 struct folio *new_folio;
 355                 struct ext2_dir_entry_2 *new_de;
 356
 357                 err = -ENOTEMPTY;
 358                 if (old_is_dir && !ext2_empty_dir(new_inode))
 359                         goto out_dir;
 360
 361                 new_de = ext2_find_entry(new_dir, &new_dentry->d_name,
 362                                          &new_folio);
 363                 if (IS_ERR(new_de)) {
 364                         err = PTR_ERR(new_de);
 365                         goto out_dir;
 366                 }
 367                 err = ext2_set_link(new_dir, new_de, new_folio, old_inode, true);
 368                 folio_release_kmap(new_folio, new_de);
 369                 if (err)
 370                         goto out_dir;
 371                 inode_set_ctime_current(new_inode);
 372                 if (old_is_dir)
 373                         drop_nlink(new_inode);
 374                 inode_dec_link_count(new_inode);
 375         } else {
 376                 err = ext2_add_link(new_dentry, old_inode);
 377                 if (err)
 378                         goto out_dir;
 379                 if (old_is_dir)
 380                         inode_inc_link_count(new_dir);
 381         }
 382
 383         /*
 384          * Like most other Unix systems, set the ctime for inodes on a
 385          * rename.
 386          */
 387         inode_set_ctime_current(old_inode);
 388         mark_inode_dirty(old_inode);
 389
 390         err = ext2_delete_entry(old_de, old_folio);
 391         if (!err && old_is_dir) {
 392                 if (old_dir != new_dir)
 393                         err = ext2_set_link(old_inode, dir_de, dir_folio,
 394                                             new_dir, false);
 395
 396                 inode_dec_link_count(old_dir);
 397         }
 398 out_dir:
 399         if (dir_de)
 400                 folio_release_kmap(dir_folio, dir_de);
 401 out_old:
 402         folio_release_kmap(old_folio, old_de);
 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         .listxattr      = ext2_listxattr,
 417         .getattr        = ext2_getattr,
 418         .setattr        = ext2_setattr,
 419         .get_inode_acl  = ext2_get_acl,
 420         .set_acl        = ext2_set_acl,
 421         .tmpfile        = ext2_tmpfile,
 422         .fileattr_get   = ext2_fileattr_get,
 423         .fileattr_set   = ext2_fileattr_set,
 424 };
 425
 426 const struct inode_operations ext2_special_inode_operations = {
 427         .listxattr      = ext2_listxattr,
 428         .getattr        = ext2_getattr,
 429         .setattr        = ext2_setattr,
 430         .get_inode_acl  = ext2_get_acl,
 431         .set_acl        = ext2_set_acl,
 432 };