fs/ext2/namei.c

   1 /*
   2  * linux/fs/ext2/namei.c
   3  *
   4  * Rewrite to pagecache. Almost all code had been changed, so blame me
   5  * if the things go wrong. Please, send bug reports to
   6  * viro@parcelfarce.linux.theplanet.co.uk
   7  *
   8  * Stuff here is basically a glue between the VFS and generic UNIXish
   9  * filesystem that keeps everything in pagecache. All knowledge of the
  10  * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
  11  * and it's easier to debug that way. In principle we might want to
  12  * generalize that a bit and turn it into a library. Or not.
  13  *
  14  * The only non-static object here is ext2_dir_inode_operations.
  15  *
  16  * TODO: get rid of kmap() use, add readahead.
  17  *
  18  * Copyright (C) 1992, 1993, 1994, 1995
  19  * Remy Card (card@masi.ibp.fr)
  20  * Laboratoire MASI - Institut Blaise Pascal
  21  * Universite Pierre et Marie Curie (Paris VI)
  22  *
  23  *  from
  24  *
  25  *  linux/fs/minix/namei.c
  26  *
  27  *  Copyright (C) 1991, 1992  Linus Torvalds
  28  *
  29  *  Big-endian to little-endian byte-swapping/bitmaps by
  30  *        David S. Miller (davem@caip.rutgers.edu), 1995
  31  */
  32
  33 #include <linux/pagemap.h>
  34 #include "ext2.h"
  35 #include "xattr.h"
  36 #include "acl.h"
  37 #include "xip.h"
  38
  39 /*
  40  * Couple of helper functions - make the code slightly cleaner.
  41  */
  42
  43 static inline void ext2_inc_count(struct inode *inode)
  44 {
  45         inode->i_nlink++;
  46         mark_inode_dirty(inode);
  47 }
  48
  49 static inline void ext2_dec_count(struct inode *inode)
  50 {
  51         inode->i_nlink--;
  52         mark_inode_dirty(inode);
  53 }
  54
  55 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  56 {
  57         int err = ext2_add_link(dentry, inode);
  58         if (!err) {
  59                 d_instantiate(dentry, inode);
  60                 return 0;
  61         }
  62         ext2_dec_count(inode);
  63         iput(inode);
  64         return err;
  65 }
  66
  67 /*
  68  * Methods themselves.
  69  */
  70
  71 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  72 {
  73         struct inode * inode;
  74         ino_t ino;
  75
  76         if (dentry->d_name.len > EXT2_NAME_LEN)
  77                 return ERR_PTR(-ENAMETOOLONG);
  78
  79         ino = ext2_inode_by_name(dir, dentry);
  80         inode = NULL;
  81         if (ino) {
  82                 inode = iget(dir->i_sb, ino);
  83                 if (!inode)
  84                         return ERR_PTR(-EACCES);
  85         }
  86         if (inode)
  87                 return d_splice_alias(inode, dentry);
  88         d_add(dentry, inode);
  89         return NULL;
  90 }
  91
  92 struct dentry *ext2_get_parent(struct dentry *child)
  93 {
  94         unsigned long ino;
  95         struct dentry *parent;
  96         struct inode *inode;
  97         struct dentry dotdot;
  98
  99         dotdot.d_name.name = "..";
 100         dotdot.d_name.len = 2;
 101
 102         ino = ext2_inode_by_name(child->d_inode, &dotdot);
 103         if (!ino)
 104                 return ERR_PTR(-ENOENT);
 105         inode = iget(child->d_inode->i_sb, ino);
 106
 107         if (!inode)
 108                 return ERR_PTR(-EACCES);
 109         parent = d_alloc_anon(inode);
 110         if (!parent) {
 111                 iput(inode);
 112                 parent = ERR_PTR(-ENOMEM);
 113         }
 114         return parent;
 115 }
 116
 117 /*
 118  * By the time this is called, we already have created
 119  * the directory cache entry for the new file, but it
 120  * is so far negative - it has no inode.
 121  *
 122  * If the create succeeds, we fill in the inode information
 123  * with d_instantiate().
 124  */
 125 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
 126 {
 127         struct inode * inode = ext2_new_inode (dir, mode);
 128         int err = PTR_ERR(inode);
 129         if (!IS_ERR(inode)) {
 130                 inode->i_op = &ext2_file_inode_operations;
 131                 if (ext2_use_xip(inode->i_sb)) {
 132                         inode->i_mapping->a_ops = &ext2_aops_xip;
 133                         inode->i_fop = &ext2_xip_file_operations;
 134                 } else if (test_opt(inode->i_sb, NOBH)) {
 135                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 136                         inode->i_fop = &ext2_file_operations;
 137                 } else {
 138                         inode->i_mapping->a_ops = &ext2_aops;
 139                         inode->i_fop = &ext2_file_operations;
 140                 }
 141                 mark_inode_dirty(inode);
 142                 err = ext2_add_nondir(dentry, inode);
 143         }
 144         return err;
 145 }
 146
 147 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 148 {
 149         struct inode * inode;
 150         int err;
 151
 152         if (!new_valid_dev(rdev))
 153                 return -EINVAL;
 154
 155         inode = ext2_new_inode (dir, mode);
 156         err = PTR_ERR(inode);
 157         if (!IS_ERR(inode)) {
 158                 init_special_inode(inode, inode->i_mode, rdev);
 159 #ifdef CONFIG_EXT2_FS_XATTR
 160                 inode->i_op = &ext2_special_inode_operations;
 161 #endif
 162                 mark_inode_dirty(inode);
 163                 err = ext2_add_nondir(dentry, inode);
 164         }
 165         return err;
 166 }
 167
 168 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 169         const char * symname)
 170 {
 171         struct super_block * sb = dir->i_sb;
 172         int err = -ENAMETOOLONG;
 173         unsigned l = strlen(symname)+1;
 174         struct inode * inode;
 175
 176         if (l > sb->s_blocksize)
 177                 goto out;
 178
 179         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 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                 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                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 198                 inode->i_size = l-1;
 199         }
 200         mark_inode_dirty(inode);
 201
 202         err = ext2_add_nondir(dentry, inode);
 203 out:
 204         return err;
 205
 206 out_fail:
 207         ext2_dec_count(inode);
 208         iput (inode);
 209         goto out;
 210 }
 211
 212 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 213         struct dentry *dentry)
 214 {
 215         struct inode *inode = old_dentry->d_inode;
 216
 217         if (inode->i_nlink >= EXT2_LINK_MAX)
 218                 return -EMLINK;
 219
 220         inode->i_ctime = CURRENT_TIME_SEC;
 221         ext2_inc_count(inode);
 222         atomic_inc(&inode->i_count);
 223
 224         return ext2_add_nondir(dentry, inode);
 225 }
 226
 227 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 228 {
 229         struct inode * inode;
 230         int err = -EMLINK;
 231
 232         if (dir->i_nlink >= EXT2_LINK_MAX)
 233                 goto out;
 234
 235         ext2_inc_count(dir);
 236
 237         inode = ext2_new_inode (dir, S_IFDIR | mode);
 238         err = PTR_ERR(inode);
 239         if (IS_ERR(inode))
 240                 goto out_dir;
 241
 242         inode->i_op = &ext2_dir_inode_operations;
 243         inode->i_fop = &ext2_dir_operations;
 244         if (test_opt(inode->i_sb, NOBH))
 245                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 246         else
 247                 inode->i_mapping->a_ops = &ext2_aops;
 248
 249         ext2_inc_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(dentry, inode);
 260 out:
 261         return err;
 262
 263 out_fail:
 264         ext2_dec_count(inode);
 265         ext2_dec_count(inode);
 266         iput(inode);
 267 out_dir:
 268         ext2_dec_count(dir);
 269         goto out;
 270 }
 271
 272 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 273 {
 274         struct inode * inode = dentry->d_inode;
 275         struct ext2_dir_entry_2 * de;
 276         struct page * page;
 277         int err = -ENOENT;
 278
 279         de = ext2_find_entry (dir, dentry, &page);
 280         if (!de)
 281                 goto out;
 282
 283         err = ext2_delete_entry (de, page);
 284         if (err)
 285                 goto out;
 286
 287         inode->i_ctime = dir->i_ctime;
 288         ext2_dec_count(inode);
 289         err = 0;
 290 out:
 291         return err;
 292 }
 293
 294 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 295 {
 296         struct inode * inode = dentry->d_inode;
 297         int err = -ENOTEMPTY;
 298
 299         if (ext2_empty_dir(inode)) {
 300                 err = ext2_unlink(dir, dentry);
 301                 if (!err) {
 302                         inode->i_size = 0;
 303                         ext2_dec_count(inode);
 304                         ext2_dec_count(dir);
 305                 }
 306         }
 307         return err;
 308 }
 309
 310 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 311         struct inode * new_dir, struct dentry * new_dentry )
 312 {
 313         struct inode * old_inode = old_dentry->d_inode;
 314         struct inode * new_inode = new_dentry->d_inode;
 315         struct page * dir_page = NULL;
 316         struct ext2_dir_entry_2 * dir_de = NULL;
 317         struct page * old_page;
 318         struct ext2_dir_entry_2 * old_de;
 319         int err = -ENOENT;
 320
 321         old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
 322         if (!old_de)
 323                 goto out;
 324
 325         if (S_ISDIR(old_inode->i_mode)) {
 326                 err = -EIO;
 327                 dir_de = ext2_dotdot(old_inode, &dir_page);
 328                 if (!dir_de)
 329                         goto out_old;
 330         }
 331
 332         if (new_inode) {
 333                 struct page *new_page;
 334                 struct ext2_dir_entry_2 *new_de;
 335
 336                 err = -ENOTEMPTY;
 337                 if (dir_de && !ext2_empty_dir (new_inode))
 338                         goto out_dir;
 339
 340                 err = -ENOENT;
 341                 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
 342                 if (!new_de)
 343                         goto out_dir;
 344                 ext2_inc_count(old_inode);
 345                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 346                 new_inode->i_ctime = CURRENT_TIME_SEC;
 347                 if (dir_de)
 348                         new_inode->i_nlink--;
 349                 ext2_dec_count(new_inode);
 350         } else {
 351                 if (dir_de) {
 352                         err = -EMLINK;
 353                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 354                                 goto out_dir;
 355                 }
 356                 ext2_inc_count(old_inode);
 357                 err = ext2_add_link(new_dentry, old_inode);
 358                 if (err) {
 359                         ext2_dec_count(old_inode);
 360                         goto out_dir;
 361                 }
 362                 if (dir_de)
 363                         ext2_inc_count(new_dir);
 364         }
 365
 366         /*
 367          * Like most other Unix systems, set the ctime for inodes on a
 368          * rename.
 369          * ext2_dec_count() will mark the inode dirty.
 370          */
 371         old_inode->i_ctime = CURRENT_TIME_SEC;
 372
 373         ext2_delete_entry (old_de, old_page);
 374         ext2_dec_count(old_inode);
 375
 376         if (dir_de) {
 377                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 378                 ext2_dec_count(old_dir);
 379         }
 380         return 0;
 381
 382
 383 out_dir:
 384         if (dir_de) {
 385                 kunmap(dir_page);
 386                 page_cache_release(dir_page);
 387         }
 388 out_old:
 389         kunmap(old_page);
 390         page_cache_release(old_page);
 391 out:
 392         return err;
 393 }
 394
 395 struct inode_operations ext2_dir_inode_operations = {
 396         .create         = ext2_create,
 397         .lookup         = ext2_lookup,
 398         .link           = ext2_link,
 399         .unlink         = ext2_unlink,
 400         .symlink        = ext2_symlink,
 401         .mkdir          = ext2_mkdir,
 402         .rmdir          = ext2_rmdir,
 403         .mknod          = ext2_mknod,
 404         .rename         = ext2_rename,
 405 #ifdef CONFIG_EXT2_FS_XATTR
 406         .setxattr       = generic_setxattr,
 407         .getxattr       = generic_getxattr,
 408         .listxattr      = ext2_listxattr,
 409         .removexattr    = generic_removexattr,
 410 #endif
 411         .setattr        = ext2_setattr,
 412         .permission     = ext2_permission,
 413 };
 414
 415 struct inode_operations ext2_special_inode_operations = {
 416 #ifdef CONFIG_EXT2_FS_XATTR
 417         .setxattr       = generic_setxattr,
 418         .getxattr       = generic_getxattr,
 419         .listxattr      = ext2_listxattr,
 420         .removexattr    = generic_removexattr,
 421 #endif
 422         .setattr        = ext2_setattr,
 423         .permission     = ext2_permission,
 424 };