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 viro@math.psu.edu
   6  *
   7  * Stuff here is basically a glue between the VFS and generic UNIXish
   8  * filesystem that keeps everything in pagecache. All knowledge of the
   9  * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
  10  * and it's easier to debug that way. In principle we might want to
  11  * generalize that a bit and turn it into a library. Or not.
  12  *
  13  * The only non-static object here is ext2_dir_inode_operations.
  14  *
  15  * TODO: get rid of kmap() use, add readahead.
  16  *
  17  * Copyright (C) 1992, 1993, 1994, 1995
  18  * Remy Card (card@masi.ibp.fr)
  19  * Laboratoire MASI - Institut Blaise Pascal
  20  * Universite Pierre et Marie Curie (Paris VI)
  21  *
  22  *  from
  23  *
  24  *  linux/fs/minix/namei.c
  25  *
  26  *  Copyright (C) 1991, 1992  Linus Torvalds
  27  *
  28  *  Big-endian to little-endian byte-swapping/bitmaps by
  29  *        David S. Miller (davem@caip.rutgers.edu), 1995
  30  */
  31
  32 #include "ext2.h"
  33 #include <linux/pagemap.h>
  34
  35 /*
  36  * Couple of helper functions - make the code slightly cleaner.
  37  */
  38
  39 static inline void ext2_inc_count(struct inode *inode)
  40 {
  41         inode->i_nlink++;
  42         mark_inode_dirty(inode);
  43 }
  44
  45 static inline void ext2_dec_count(struct inode *inode)
  46 {
  47         inode->i_nlink--;
  48         mark_inode_dirty(inode);
  49 }
  50
  51 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  52 {
  53         int err = ext2_add_link(dentry, inode);
  54         if (!err) {
  55                 d_instantiate(dentry, inode);
  56                 return 0;
  57         }
  58         ext2_dec_count(inode);
  59         iput(inode);
  60         return err;
  61 }
  62
  63 /*
  64  * Methods themselves.
  65  */
  66
  67 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry)
  68 {
  69         struct inode * inode;
  70         ino_t ino;
  71
  72         if (dentry->d_name.len > EXT2_NAME_LEN)
  73                 return ERR_PTR(-ENAMETOOLONG);
  74
  75         ino = ext2_inode_by_name(dir, dentry);
  76         inode = NULL;
  77         if (ino) {
  78                 inode = iget(dir->i_sb, ino);
  79                 if (!inode)
  80                         return ERR_PTR(-EACCES);
  81         }
  82         if (inode)
  83                 return d_splice_alias(inode, dentry);
  84         d_add(dentry, inode);
  85         return NULL;
  86 }
  87
  88 struct dentry *ext2_get_parent(struct dentry *child)
  89 {
  90         unsigned long ino;
  91         struct dentry *parent;
  92         struct inode *inode;
  93         struct dentry dotdot;
  94
  95         dotdot.d_name.name = "..";
  96         dotdot.d_name.len = 2;
  97
  98         ino = ext2_inode_by_name(child->d_inode, &dotdot);
  99         if (!ino)
 100                 return ERR_PTR(-ENOENT);
 101         inode = iget(child->d_inode->i_sb, ino);
 102
 103         if (!inode)
 104                 return ERR_PTR(-EACCES);
 105         parent = d_alloc_anon(inode);
 106         if (!parent) {
 107                 iput(inode);
 108                 parent = ERR_PTR(-ENOMEM);
 109         }
 110         return parent;
 111 }
 112
 113 /*
 114  * By the time this is called, we already have created
 115  * the directory cache entry for the new file, but it
 116  * is so far negative - it has no inode.
 117  *
 118  * If the create succeeds, we fill in the inode information
 119  * with d_instantiate().
 120  */
 121 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode)
 122 {
 123         struct inode * inode = ext2_new_inode (dir, mode);
 124         int err = PTR_ERR(inode);
 125         if (!IS_ERR(inode)) {
 126                 inode->i_op = &ext2_file_inode_operations;
 127                 inode->i_fop = &ext2_file_operations;
 128                 inode->i_mapping->a_ops = &ext2_aops;
 129                 mark_inode_dirty(inode);
 130                 err = ext2_add_nondir(dentry, inode);
 131         }
 132         return err;
 133 }
 134
 135 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, int rdev)
 136 {
 137         struct inode * inode = ext2_new_inode (dir, mode);
 138         int err = PTR_ERR(inode);
 139         if (!IS_ERR(inode)) {
 140                 init_special_inode(inode, mode, rdev);
 141                 mark_inode_dirty(inode);
 142                 err = ext2_add_nondir(dentry, inode);
 143         }
 144         return err;
 145 }
 146
 147 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 148         const char * symname)
 149 {
 150         struct super_block * sb = dir->i_sb;
 151         int err = -ENAMETOOLONG;
 152         unsigned l = strlen(symname)+1;
 153         struct inode * inode;
 154
 155         if (l > sb->s_blocksize)
 156                 goto out;
 157
 158         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 159         err = PTR_ERR(inode);
 160         if (IS_ERR(inode))
 161                 goto out;
 162
 163         if (l > sizeof (EXT2_I(inode)->i_data)) {
 164                 /* slow symlink */
 165                 inode->i_op = &page_symlink_inode_operations;
 166                 inode->i_mapping->a_ops = &ext2_aops;
 167                 err = page_symlink(inode, symname, l);
 168                 if (err)
 169                         goto out_fail;
 170         } else {
 171                 /* fast symlink */
 172                 inode->i_op = &ext2_fast_symlink_inode_operations;
 173                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 174                 inode->i_size = l-1;
 175         }
 176         mark_inode_dirty(inode);
 177
 178         err = ext2_add_nondir(dentry, inode);
 179 out:
 180         return err;
 181
 182 out_fail:
 183         ext2_dec_count(inode);
 184         iput (inode);
 185         goto out;
 186 }
 187
 188 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 189         struct dentry *dentry)
 190 {
 191         struct inode *inode = old_dentry->d_inode;
 192
 193         if (inode->i_nlink >= EXT2_LINK_MAX)
 194                 return -EMLINK;
 195
 196         inode->i_ctime = CURRENT_TIME;
 197         ext2_inc_count(inode);
 198         atomic_inc(&inode->i_count);
 199
 200         return ext2_add_nondir(dentry, inode);
 201 }
 202
 203 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 204 {
 205         struct inode * inode;
 206         int err = -EMLINK;
 207
 208         if (dir->i_nlink >= EXT2_LINK_MAX)
 209                 goto out;
 210
 211         ext2_inc_count(dir);
 212
 213         inode = ext2_new_inode (dir, S_IFDIR | mode);
 214         err = PTR_ERR(inode);
 215         if (IS_ERR(inode))
 216                 goto out_dir;
 217
 218         inode->i_op = &ext2_dir_inode_operations;
 219         inode->i_fop = &ext2_dir_operations;
 220         inode->i_mapping->a_ops = &ext2_aops;
 221
 222         ext2_inc_count(inode);
 223
 224         err = ext2_make_empty(inode, dir);
 225         if (err)
 226                 goto out_fail;
 227
 228         err = ext2_add_link(dentry, inode);
 229         if (err)
 230                 goto out_fail;
 231
 232         d_instantiate(dentry, inode);
 233 out:
 234         return err;
 235
 236 out_fail:
 237         ext2_dec_count(inode);
 238         ext2_dec_count(inode);
 239         iput(inode);
 240 out_dir:
 241         ext2_dec_count(dir);
 242         goto out;
 243 }
 244
 245 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 246 {
 247         struct inode * inode = dentry->d_inode;
 248         struct ext2_dir_entry_2 * de;
 249         struct page * page;
 250         int err = -ENOENT;
 251
 252         de = ext2_find_entry (dir, dentry, &page);
 253         if (!de)
 254                 goto out;
 255
 256         err = ext2_delete_entry (de, page);
 257         if (err)
 258                 goto out;
 259
 260         inode->i_ctime = dir->i_ctime;
 261         ext2_dec_count(inode);
 262         err = 0;
 263 out:
 264         return err;
 265 }
 266
 267 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 268 {
 269         struct inode * inode = dentry->d_inode;
 270         int err = -ENOTEMPTY;
 271
 272         if (ext2_empty_dir(inode)) {
 273                 err = ext2_unlink(dir, dentry);
 274                 if (!err) {
 275                         inode->i_size = 0;
 276                         ext2_dec_count(inode);
 277                         ext2_dec_count(dir);
 278                 }
 279         }
 280         return err;
 281 }
 282
 283 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 284         struct inode * new_dir, struct dentry * new_dentry )
 285 {
 286         struct inode * old_inode = old_dentry->d_inode;
 287         struct inode * new_inode = new_dentry->d_inode;
 288         struct page * dir_page = NULL;
 289         struct ext2_dir_entry_2 * dir_de = NULL;
 290         struct page * old_page;
 291         struct ext2_dir_entry_2 * old_de;
 292         int err = -ENOENT;
 293
 294         old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
 295         if (!old_de)
 296                 goto out;
 297
 298         if (S_ISDIR(old_inode->i_mode)) {
 299                 err = -EIO;
 300                 dir_de = ext2_dotdot(old_inode, &dir_page);
 301                 if (!dir_de)
 302                         goto out_old;
 303         }
 304
 305         if (new_inode) {
 306                 struct page *new_page;
 307                 struct ext2_dir_entry_2 *new_de;
 308
 309                 err = -ENOTEMPTY;
 310                 if (dir_de && !ext2_empty_dir (new_inode))
 311                         goto out_dir;
 312
 313                 err = -ENOENT;
 314                 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
 315                 if (!new_de)
 316                         goto out_dir;
 317                 ext2_inc_count(old_inode);
 318                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 319                 new_inode->i_ctime = CURRENT_TIME;
 320                 if (dir_de)
 321                         new_inode->i_nlink--;
 322                 ext2_dec_count(new_inode);
 323         } else {
 324                 if (dir_de) {
 325                         err = -EMLINK;
 326                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 327                                 goto out_dir;
 328                 }
 329                 ext2_inc_count(old_inode);
 330                 err = ext2_add_link(new_dentry, old_inode);
 331                 if (err) {
 332                         ext2_dec_count(old_inode);
 333                         goto out_dir;
 334                 }
 335                 if (dir_de)
 336                         ext2_inc_count(new_dir);
 337         }
 338
 339         ext2_delete_entry (old_de, old_page);
 340         ext2_dec_count(old_inode);
 341
 342         if (dir_de) {
 343                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 344                 ext2_dec_count(old_dir);
 345         }
 346         return 0;
 347
 348
 349 out_dir:
 350         if (dir_de) {
 351                 kunmap(dir_page);
 352                 page_cache_release(dir_page);
 353         }
 354 out_old:
 355         kunmap(old_page);
 356         page_cache_release(old_page);
 357 out:
 358         return err;
 359 }
 360
 361 struct inode_operations ext2_dir_inode_operations = {
 362         .create         = ext2_create,
 363         .lookup         = ext2_lookup,
 364         .link           = ext2_link,
 365         .unlink         = ext2_unlink,
 366         .symlink        = ext2_symlink,
 367         .mkdir          = ext2_mkdir,
 368         .rmdir          = ext2_rmdir,
 369         .mknod          = ext2_mknod,
 370         .rename         = ext2_rename,
 371 };