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         struct qstr dotdot = QSTR_INIT("..", 2);
  85         ino_t ino;
  86         int res;
  87
  88         res = ext2_inode_by_name(d_inode(child), &dotdot, &ino);
  89         if (res)
  90                 return ERR_PTR(res);
  91
  92         return d_obtain_alias(ext2_iget(child->d_sb, ino));
  93 }
  94
  95 /*
  96  * By the time this is called, we already have created
  97  * the directory cache entry for the new file, but it
  98  * is so far negative - it has no inode.
  99  *
 100  * If the create succeeds, we fill in the inode information
 101  * with d_instantiate().
 102  */
 103 static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
 104 {
 105         struct inode *inode;
 106         int err;
 107
 108         err = dquot_initialize(dir);
 109         if (err)
 110                 return err;
 111
 112         inode = ext2_new_inode(dir, mode, &dentry->d_name);
 113         if (IS_ERR(inode))
 114                 return PTR_ERR(inode);
 115
 116         ext2_set_file_ops(inode);
 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         ext2_set_file_ops(inode);
 128         mark_inode_dirty(inode);
 129         d_tmpfile(dentry, inode);
 130         unlock_new_inode(inode);
 131         return 0;
 132 }
 133
 134 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 135 {
 136         struct inode * inode;
 137         int err;
 138
 139         err = dquot_initialize(dir);
 140         if (err)
 141                 return err;
 142
 143         inode = ext2_new_inode (dir, mode, &dentry->d_name);
 144         err = PTR_ERR(inode);
 145         if (!IS_ERR(inode)) {
 146                 init_special_inode(inode, inode->i_mode, rdev);
 147                 inode->i_op = &ext2_special_inode_operations;
 148                 mark_inode_dirty(inode);
 149                 err = ext2_add_nondir(dentry, inode);
 150         }
 151         return err;
 152 }
 153
 154 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 155         const char * symname)
 156 {
 157         struct super_block * sb = dir->i_sb;
 158         int err = -ENAMETOOLONG;
 159         unsigned l = strlen(symname)+1;
 160         struct inode * inode;
 161
 162         if (l > sb->s_blocksize)
 163                 goto out;
 164
 165         err = dquot_initialize(dir);
 166         if (err)
 167                 goto out;
 168
 169         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 170         err = PTR_ERR(inode);
 171         if (IS_ERR(inode))
 172                 goto out;
 173
 174         if (l > sizeof (EXT2_I(inode)->i_data)) {
 175                 /* slow symlink */
 176                 inode->i_op = &ext2_symlink_inode_operations;
 177                 inode_nohighmem(inode);
 178                 if (test_opt(inode->i_sb, NOBH))
 179                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 180                 else
 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->i_ctime = current_time(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 inode * dir, struct dentry * dentry, umode_t mode)
 229 {
 230         struct inode * inode;
 231         int err;
 232
 233         err = dquot_initialize(dir);
 234         if (err)
 235                 return err;
 236
 237         inode_inc_link_count(dir);
 238
 239         inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 240         err = PTR_ERR(inode);
 241         if (IS_ERR(inode))
 242                 goto out_dir;
 243
 244         inode->i_op = &ext2_dir_inode_operations;
 245         inode->i_fop = &ext2_dir_operations;
 246         if (test_opt(inode->i_sb, NOBH))
 247                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 248         else
 249                 inode->i_mapping->a_ops = &ext2_aops;
 250
 251         inode_inc_link_count(inode);
 252
 253         err = ext2_make_empty(inode, dir);
 254         if (err)
 255                 goto out_fail;
 256
 257         err = ext2_add_link(dentry, inode);
 258         if (err)
 259                 goto out_fail;
 260
 261         d_instantiate_new(dentry, inode);
 262 out:
 263         return err;
 264
 265 out_fail:
 266         inode_dec_link_count(inode);
 267         inode_dec_link_count(inode);
 268         discard_new_inode(inode);
 269 out_dir:
 270         inode_dec_link_count(dir);
 271         goto out;
 272 }
 273
 274 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 275 {
 276         struct inode * inode = d_inode(dentry);
 277         struct ext2_dir_entry_2 * de;
 278         struct page * page;
 279         int err;
 280
 281         err = dquot_initialize(dir);
 282         if (err)
 283                 goto out;
 284
 285         de = ext2_find_entry(dir, &dentry->d_name, &page);
 286         if (IS_ERR(de)) {
 287                 err = PTR_ERR(de);
 288                 goto out;
 289         }
 290
 291         err = ext2_delete_entry (de, page);
 292         if (err)
 293                 goto out;
 294
 295         inode->i_ctime = dir->i_ctime;
 296         inode_dec_link_count(inode);
 297         err = 0;
 298 out:
 299         return err;
 300 }
 301
 302 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 303 {
 304         struct inode * inode = d_inode(dentry);
 305         int err = -ENOTEMPTY;
 306
 307         if (ext2_empty_dir(inode)) {
 308                 err = ext2_unlink(dir, dentry);
 309                 if (!err) {
 310                         inode->i_size = 0;
 311                         inode_dec_link_count(inode);
 312                         inode_dec_link_count(dir);
 313                 }
 314         }
 315         return err;
 316 }
 317
 318 static int ext2_rename (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 page * dir_page = NULL;
 325         struct ext2_dir_entry_2 * dir_de = NULL;
 326         struct page * old_page;
 327         struct ext2_dir_entry_2 * old_de;
 328         int err;
 329
 330         if (flags & ~RENAME_NOREPLACE)
 331                 return -EINVAL;
 332
 333         err = dquot_initialize(old_dir);
 334         if (err)
 335                 goto out;
 336
 337         err = dquot_initialize(new_dir);
 338         if (err)
 339                 goto out;
 340
 341         old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_page);
 342         if (IS_ERR(old_de)) {
 343                 err = PTR_ERR(old_de);
 344                 goto out;
 345         }
 346
 347         if (S_ISDIR(old_inode->i_mode)) {
 348                 err = -EIO;
 349                 dir_de = ext2_dotdot(old_inode, &dir_page);
 350                 if (!dir_de)
 351                         goto out_old;
 352         }
 353
 354         if (new_inode) {
 355                 struct page *new_page;
 356                 struct ext2_dir_entry_2 *new_de;
 357
 358                 err = -ENOTEMPTY;
 359                 if (dir_de && !ext2_empty_dir (new_inode))
 360                         goto out_dir;
 361
 362                 new_de = ext2_find_entry(new_dir, &new_dentry->d_name, &new_page);
 363                 if (IS_ERR(new_de)) {
 364                         err = PTR_ERR(new_de);
 365                         goto out_dir;
 366                 }
 367                 ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 368                 new_inode->i_ctime = current_time(new_inode);
 369                 if (dir_de)
 370                         drop_nlink(new_inode);
 371                 inode_dec_link_count(new_inode);
 372         } else {
 373                 err = ext2_add_link(new_dentry, old_inode);
 374                 if (err)
 375                         goto out_dir;
 376                 if (dir_de)
 377                         inode_inc_link_count(new_dir);
 378         }
 379
 380         /*
 381          * Like most other Unix systems, set the ctime for inodes on a
 382          * rename.
 383          */
 384         old_inode->i_ctime = current_time(old_inode);
 385         mark_inode_dirty(old_inode);
 386
 387         ext2_delete_entry (old_de, old_page);
 388
 389         if (dir_de) {
 390                 if (old_dir != new_dir)
 391                         ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 392                 else {
 393                         kunmap(dir_page);
 394                         put_page(dir_page);
 395                 }
 396                 inode_dec_link_count(old_dir);
 397         }
 398         return 0;
 399
 400
 401 out_dir:
 402         if (dir_de) {
 403                 kunmap(dir_page);
 404                 put_page(dir_page);
 405         }
 406 out_old:
 407         kunmap(old_page);
 408         put_page(old_page);
 409 out:
 410         return err;
 411 }
 412
 413 const struct inode_operations ext2_dir_inode_operations = {
 414         .create         = ext2_create,
 415         .lookup         = ext2_lookup,
 416         .link           = ext2_link,
 417         .unlink         = ext2_unlink,
 418         .symlink        = ext2_symlink,
 419         .mkdir          = ext2_mkdir,
 420         .rmdir          = ext2_rmdir,
 421         .mknod          = ext2_mknod,
 422         .rename         = ext2_rename,
 423         .listxattr      = ext2_listxattr,
 424         .getattr        = ext2_getattr,
 425         .setattr        = ext2_setattr,
 426         .get_acl        = ext2_get_acl,
 427         .set_acl        = ext2_set_acl,
 428         .tmpfile        = ext2_tmpfile,
 429 };
 430
 431 const struct inode_operations ext2_special_inode_operations = {
 432         .listxattr      = ext2_listxattr,
 433         .getattr        = ext2_getattr,
 434         .setattr        = ext2_setattr,
 435         .get_acl        = ext2_get_acl,
 436         .set_acl        = ext2_set_acl,
 437 };