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         return d_splice_alias(inode, dentry);
  87 }
  88
  89 struct dentry *ext2_get_parent(struct dentry *child)
  90 {
  91         unsigned long ino;
  92         struct dentry *parent;
  93         struct inode *inode;
  94         struct dentry dotdot;
  95
  96         dotdot.d_name.name = "..";
  97         dotdot.d_name.len = 2;
  98
  99         ino = ext2_inode_by_name(child->d_inode, &dotdot);
 100         if (!ino)
 101                 return ERR_PTR(-ENOENT);
 102         inode = iget(child->d_inode->i_sb, ino);
 103
 104         if (!inode)
 105                 return ERR_PTR(-EACCES);
 106         parent = d_alloc_anon(inode);
 107         if (!parent) {
 108                 iput(inode);
 109                 parent = ERR_PTR(-ENOMEM);
 110         }
 111         return parent;
 112 }
 113
 114 /*
 115  * By the time this is called, we already have created
 116  * the directory cache entry for the new file, but it
 117  * is so far negative - it has no inode.
 118  *
 119  * If the create succeeds, we fill in the inode information
 120  * with d_instantiate().
 121  */
 122 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
 123 {
 124         struct inode * inode = ext2_new_inode (dir, mode);
 125         int err = PTR_ERR(inode);
 126         if (!IS_ERR(inode)) {
 127                 inode->i_op = &ext2_file_inode_operations;
 128                 if (ext2_use_xip(inode->i_sb)) {
 129                         inode->i_mapping->a_ops = &ext2_aops_xip;
 130                         inode->i_fop = &ext2_xip_file_operations;
 131                 } else if (test_opt(inode->i_sb, NOBH)) {
 132                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 133                         inode->i_fop = &ext2_file_operations;
 134                 } else {
 135                         inode->i_mapping->a_ops = &ext2_aops;
 136                         inode->i_fop = &ext2_file_operations;
 137                 }
 138                 mark_inode_dirty(inode);
 139                 err = ext2_add_nondir(dentry, inode);
 140         }
 141         return err;
 142 }
 143
 144 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 145 {
 146         struct inode * inode;
 147         int err;
 148
 149         if (!new_valid_dev(rdev))
 150                 return -EINVAL;
 151
 152         inode = ext2_new_inode (dir, mode);
 153         err = PTR_ERR(inode);
 154         if (!IS_ERR(inode)) {
 155                 init_special_inode(inode, inode->i_mode, rdev);
 156 #ifdef CONFIG_EXT2_FS_XATTR
 157                 inode->i_op = &ext2_special_inode_operations;
 158 #endif
 159                 mark_inode_dirty(inode);
 160                 err = ext2_add_nondir(dentry, inode);
 161         }
 162         return err;
 163 }
 164
 165 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 166         const char * symname)
 167 {
 168         struct super_block * sb = dir->i_sb;
 169         int err = -ENAMETOOLONG;
 170         unsigned l = strlen(symname)+1;
 171         struct inode * inode;
 172
 173         if (l > sb->s_blocksize)
 174                 goto out;
 175
 176         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 177         err = PTR_ERR(inode);
 178         if (IS_ERR(inode))
 179                 goto out;
 180
 181         if (l > sizeof (EXT2_I(inode)->i_data)) {
 182                 /* slow symlink */
 183                 inode->i_op = &ext2_symlink_inode_operations;
 184                 if (test_opt(inode->i_sb, NOBH))
 185                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 186                 else
 187                         inode->i_mapping->a_ops = &ext2_aops;
 188                 err = page_symlink(inode, symname, l);
 189                 if (err)
 190                         goto out_fail;
 191         } else {
 192                 /* fast symlink */
 193                 inode->i_op = &ext2_fast_symlink_inode_operations;
 194                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 195                 inode->i_size = l-1;
 196         }
 197         mark_inode_dirty(inode);
 198
 199         err = ext2_add_nondir(dentry, inode);
 200 out:
 201         return err;
 202
 203 out_fail:
 204         ext2_dec_count(inode);
 205         iput (inode);
 206         goto out;
 207 }
 208
 209 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 210         struct dentry *dentry)
 211 {
 212         struct inode *inode = old_dentry->d_inode;
 213
 214         if (inode->i_nlink >= EXT2_LINK_MAX)
 215                 return -EMLINK;
 216
 217         inode->i_ctime = CURRENT_TIME_SEC;
 218         ext2_inc_count(inode);
 219         atomic_inc(&inode->i_count);
 220
 221         return ext2_add_nondir(dentry, inode);
 222 }
 223
 224 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 225 {
 226         struct inode * inode;
 227         int err = -EMLINK;
 228
 229         if (dir->i_nlink >= EXT2_LINK_MAX)
 230                 goto out;
 231
 232         ext2_inc_count(dir);
 233
 234         inode = ext2_new_inode (dir, S_IFDIR | mode);
 235         err = PTR_ERR(inode);
 236         if (IS_ERR(inode))
 237                 goto out_dir;
 238
 239         inode->i_op = &ext2_dir_inode_operations;
 240         inode->i_fop = &ext2_dir_operations;
 241         if (test_opt(inode->i_sb, NOBH))
 242                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 243         else
 244                 inode->i_mapping->a_ops = &ext2_aops;
 245
 246         ext2_inc_count(inode);
 247
 248         err = ext2_make_empty(inode, dir);
 249         if (err)
 250                 goto out_fail;
 251
 252         err = ext2_add_link(dentry, inode);
 253         if (err)
 254                 goto out_fail;
 255
 256         d_instantiate(dentry, inode);
 257 out:
 258         return err;
 259
 260 out_fail:
 261         ext2_dec_count(inode);
 262         ext2_dec_count(inode);
 263         iput(inode);
 264 out_dir:
 265         ext2_dec_count(dir);
 266         goto out;
 267 }
 268
 269 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 270 {
 271         struct inode * inode = dentry->d_inode;
 272         struct ext2_dir_entry_2 * de;
 273         struct page * page;
 274         int err = -ENOENT;
 275
 276         de = ext2_find_entry (dir, dentry, &page);
 277         if (!de)
 278                 goto out;
 279
 280         err = ext2_delete_entry (de, page);
 281         if (err)
 282                 goto out;
 283
 284         inode->i_ctime = dir->i_ctime;
 285         ext2_dec_count(inode);
 286         err = 0;
 287 out:
 288         return err;
 289 }
 290
 291 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 292 {
 293         struct inode * inode = dentry->d_inode;
 294         int err = -ENOTEMPTY;
 295
 296         if (ext2_empty_dir(inode)) {
 297                 err = ext2_unlink(dir, dentry);
 298                 if (!err) {
 299                         inode->i_size = 0;
 300                         ext2_dec_count(inode);
 301                         ext2_dec_count(dir);
 302                 }
 303         }
 304         return err;
 305 }
 306
 307 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 308         struct inode * new_dir, struct dentry * new_dentry )
 309 {
 310         struct inode * old_inode = old_dentry->d_inode;
 311         struct inode * new_inode = new_dentry->d_inode;
 312         struct page * dir_page = NULL;
 313         struct ext2_dir_entry_2 * dir_de = NULL;
 314         struct page * old_page;
 315         struct ext2_dir_entry_2 * old_de;
 316         int err = -ENOENT;
 317
 318         old_de = ext2_find_entry (old_dir, old_dentry, &old_page);
 319         if (!old_de)
 320                 goto out;
 321
 322         if (S_ISDIR(old_inode->i_mode)) {
 323                 err = -EIO;
 324                 dir_de = ext2_dotdot(old_inode, &dir_page);
 325                 if (!dir_de)
 326                         goto out_old;
 327         }
 328
 329         if (new_inode) {
 330                 struct page *new_page;
 331                 struct ext2_dir_entry_2 *new_de;
 332
 333                 err = -ENOTEMPTY;
 334                 if (dir_de && !ext2_empty_dir (new_inode))
 335                         goto out_dir;
 336
 337                 err = -ENOENT;
 338                 new_de = ext2_find_entry (new_dir, new_dentry, &new_page);
 339                 if (!new_de)
 340                         goto out_dir;
 341                 ext2_inc_count(old_inode);
 342                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 343                 new_inode->i_ctime = CURRENT_TIME_SEC;
 344                 if (dir_de)
 345                         new_inode->i_nlink--;
 346                 ext2_dec_count(new_inode);
 347         } else {
 348                 if (dir_de) {
 349                         err = -EMLINK;
 350                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 351                                 goto out_dir;
 352                 }
 353                 ext2_inc_count(old_inode);
 354                 err = ext2_add_link(new_dentry, old_inode);
 355                 if (err) {
 356                         ext2_dec_count(old_inode);
 357                         goto out_dir;
 358                 }
 359                 if (dir_de)
 360                         ext2_inc_count(new_dir);
 361         }
 362
 363         /*
 364          * Like most other Unix systems, set the ctime for inodes on a
 365          * rename.
 366          * ext2_dec_count() will mark the inode dirty.
 367          */
 368         old_inode->i_ctime = CURRENT_TIME_SEC;
 369
 370         ext2_delete_entry (old_de, old_page);
 371         ext2_dec_count(old_inode);
 372
 373         if (dir_de) {
 374                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 375                 ext2_dec_count(old_dir);
 376         }
 377         return 0;
 378
 379
 380 out_dir:
 381         if (dir_de) {
 382                 kunmap(dir_page);
 383                 page_cache_release(dir_page);
 384         }
 385 out_old:
 386         kunmap(old_page);
 387         page_cache_release(old_page);
 388 out:
 389         return err;
 390 }
 391
 392 struct inode_operations ext2_dir_inode_operations = {
 393         .create         = ext2_create,
 394         .lookup         = ext2_lookup,
 395         .link           = ext2_link,
 396         .unlink         = ext2_unlink,
 397         .symlink        = ext2_symlink,
 398         .mkdir          = ext2_mkdir,
 399         .rmdir          = ext2_rmdir,
 400         .mknod          = ext2_mknod,
 401         .rename         = ext2_rename,
 402 #ifdef CONFIG_EXT2_FS_XATTR
 403         .setxattr       = generic_setxattr,
 404         .getxattr       = generic_getxattr,
 405         .listxattr      = ext2_listxattr,
 406         .removexattr    = generic_removexattr,
 407 #endif
 408         .setattr        = ext2_setattr,
 409         .permission     = ext2_permission,
 410 };
 411
 412 struct inode_operations ext2_special_inode_operations = {
 413 #ifdef CONFIG_EXT2_FS_XATTR
 414         .setxattr       = generic_setxattr,
 415         .getxattr       = generic_getxattr,
 416         .listxattr      = ext2_listxattr,
 417         .removexattr    = generic_removexattr,
 418 #endif
 419         .setattr        = ext2_setattr,
 420         .permission     = ext2_permission,
 421 };