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 static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  40 {
  41         int err = ext2_add_link(dentry, inode);
  42         if (!err) {
  43                 d_instantiate(dentry, inode);
  44                 return 0;
  45         }
  46         inode_dec_link_count(inode);
  47         iput(inode);
  48         return err;
  49 }
  50
  51 /*
  52  * Methods themselves.
  53  */
  54
  55 static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  56 {
  57         struct inode * inode;
  58         ino_t ino;
  59
  60         if (dentry->d_name.len > EXT2_NAME_LEN)
  61                 return ERR_PTR(-ENAMETOOLONG);
  62
  63         ino = ext2_inode_by_name(dir, &dentry->d_name);
  64         inode = NULL;
  65         if (ino) {
  66                 inode = ext2_iget(dir->i_sb, ino);
  67                 if (IS_ERR(inode))
  68                         return ERR_CAST(inode);
  69         }
  70         return d_splice_alias(inode, dentry);
  71 }
  72
  73 struct dentry *ext2_get_parent(struct dentry *child)
  74 {
  75         struct qstr dotdot = {.name = "..", .len = 2};
  76         unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
  77         if (!ino)
  78                 return ERR_PTR(-ENOENT);
  79         return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
  80 }
  81
  82 /*
  83  * By the time this is called, we already have created
  84  * the directory cache entry for the new file, but it
  85  * is so far negative - it has no inode.
  86  *
  87  * If the create succeeds, we fill in the inode information
  88  * with d_instantiate().
  89  */
  90 static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
  91 {
  92         struct inode * inode = ext2_new_inode (dir, mode);
  93         int err = PTR_ERR(inode);
  94         if (!IS_ERR(inode)) {
  95                 inode->i_op = &ext2_file_inode_operations;
  96                 if (ext2_use_xip(inode->i_sb)) {
  97                         inode->i_mapping->a_ops = &ext2_aops_xip;
  98                         inode->i_fop = &ext2_xip_file_operations;
  99                 } else if (test_opt(inode->i_sb, NOBH)) {
 100                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 101                         inode->i_fop = &ext2_file_operations;
 102                 } else {
 103                         inode->i_mapping->a_ops = &ext2_aops;
 104                         inode->i_fop = &ext2_file_operations;
 105                 }
 106                 mark_inode_dirty(inode);
 107                 err = ext2_add_nondir(dentry, inode);
 108         }
 109         return err;
 110 }
 111
 112 static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
 113 {
 114         struct inode * inode;
 115         int err;
 116
 117         if (!new_valid_dev(rdev))
 118                 return -EINVAL;
 119
 120         inode = ext2_new_inode (dir, mode);
 121         err = PTR_ERR(inode);
 122         if (!IS_ERR(inode)) {
 123                 init_special_inode(inode, inode->i_mode, rdev);
 124 #ifdef CONFIG_EXT2_FS_XATTR
 125                 inode->i_op = &ext2_special_inode_operations;
 126 #endif
 127                 mark_inode_dirty(inode);
 128                 err = ext2_add_nondir(dentry, inode);
 129         }
 130         return err;
 131 }
 132
 133 static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 134         const char * symname)
 135 {
 136         struct super_block * sb = dir->i_sb;
 137         int err = -ENAMETOOLONG;
 138         unsigned l = strlen(symname)+1;
 139         struct inode * inode;
 140
 141         if (l > sb->s_blocksize)
 142                 goto out;
 143
 144         inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO);
 145         err = PTR_ERR(inode);
 146         if (IS_ERR(inode))
 147                 goto out;
 148
 149         if (l > sizeof (EXT2_I(inode)->i_data)) {
 150                 /* slow symlink */
 151                 inode->i_op = &ext2_symlink_inode_operations;
 152                 if (test_opt(inode->i_sb, NOBH))
 153                         inode->i_mapping->a_ops = &ext2_nobh_aops;
 154                 else
 155                         inode->i_mapping->a_ops = &ext2_aops;
 156                 err = page_symlink(inode, symname, l);
 157                 if (err)
 158                         goto out_fail;
 159         } else {
 160                 /* fast symlink */
 161                 inode->i_op = &ext2_fast_symlink_inode_operations;
 162                 memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 163                 inode->i_size = l-1;
 164         }
 165         mark_inode_dirty(inode);
 166
 167         err = ext2_add_nondir(dentry, inode);
 168 out:
 169         return err;
 170
 171 out_fail:
 172         inode_dec_link_count(inode);
 173         iput (inode);
 174         goto out;
 175 }
 176
 177 static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 178         struct dentry *dentry)
 179 {
 180         struct inode *inode = old_dentry->d_inode;
 181
 182         if (inode->i_nlink >= EXT2_LINK_MAX)
 183                 return -EMLINK;
 184
 185         inode->i_ctime = CURRENT_TIME_SEC;
 186         inode_inc_link_count(inode);
 187         atomic_inc(&inode->i_count);
 188
 189         return ext2_add_nondir(dentry, inode);
 190 }
 191
 192 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
 193 {
 194         struct inode * inode;
 195         int err = -EMLINK;
 196
 197         if (dir->i_nlink >= EXT2_LINK_MAX)
 198                 goto out;
 199
 200         inode_inc_link_count(dir);
 201
 202         inode = ext2_new_inode (dir, S_IFDIR | mode);
 203         err = PTR_ERR(inode);
 204         if (IS_ERR(inode))
 205                 goto out_dir;
 206
 207         inode->i_op = &ext2_dir_inode_operations;
 208         inode->i_fop = &ext2_dir_operations;
 209         if (test_opt(inode->i_sb, NOBH))
 210                 inode->i_mapping->a_ops = &ext2_nobh_aops;
 211         else
 212                 inode->i_mapping->a_ops = &ext2_aops;
 213
 214         inode_inc_link_count(inode);
 215
 216         err = ext2_make_empty(inode, dir);
 217         if (err)
 218                 goto out_fail;
 219
 220         err = ext2_add_link(dentry, inode);
 221         if (err)
 222                 goto out_fail;
 223
 224         d_instantiate(dentry, inode);
 225 out:
 226         return err;
 227
 228 out_fail:
 229         inode_dec_link_count(inode);
 230         inode_dec_link_count(inode);
 231         iput(inode);
 232 out_dir:
 233         inode_dec_link_count(dir);
 234         goto out;
 235 }
 236
 237 static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 238 {
 239         struct inode * inode = dentry->d_inode;
 240         struct ext2_dir_entry_2 * de;
 241         struct page * page;
 242         int err = -ENOENT;
 243
 244         de = ext2_find_entry (dir, &dentry->d_name, &page);
 245         if (!de)
 246                 goto out;
 247
 248         err = ext2_delete_entry (de, page);
 249         if (err)
 250                 goto out;
 251
 252         inode->i_ctime = dir->i_ctime;
 253         inode_dec_link_count(inode);
 254         err = 0;
 255 out:
 256         return err;
 257 }
 258
 259 static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 260 {
 261         struct inode * inode = dentry->d_inode;
 262         int err = -ENOTEMPTY;
 263
 264         if (ext2_empty_dir(inode)) {
 265                 err = ext2_unlink(dir, dentry);
 266                 if (!err) {
 267                         inode->i_size = 0;
 268                         inode_dec_link_count(inode);
 269                         inode_dec_link_count(dir);
 270                 }
 271         }
 272         return err;
 273 }
 274
 275 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 276         struct inode * new_dir, struct dentry * new_dentry )
 277 {
 278         struct inode * old_inode = old_dentry->d_inode;
 279         struct inode * new_inode = new_dentry->d_inode;
 280         struct page * dir_page = NULL;
 281         struct ext2_dir_entry_2 * dir_de = NULL;
 282         struct page * old_page;
 283         struct ext2_dir_entry_2 * old_de;
 284         int err = -ENOENT;
 285
 286         old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 287         if (!old_de)
 288                 goto out;
 289
 290         if (S_ISDIR(old_inode->i_mode)) {
 291                 err = -EIO;
 292                 dir_de = ext2_dotdot(old_inode, &dir_page);
 293                 if (!dir_de)
 294                         goto out_old;
 295         }
 296
 297         if (new_inode) {
 298                 struct page *new_page;
 299                 struct ext2_dir_entry_2 *new_de;
 300
 301                 err = -ENOTEMPTY;
 302                 if (dir_de && !ext2_empty_dir (new_inode))
 303                         goto out_dir;
 304
 305                 err = -ENOENT;
 306                 new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 307                 if (!new_de)
 308                         goto out_dir;
 309                 inode_inc_link_count(old_inode);
 310                 ext2_set_link(new_dir, new_de, new_page, old_inode);
 311                 new_inode->i_ctime = CURRENT_TIME_SEC;
 312                 if (dir_de)
 313                         drop_nlink(new_inode);
 314                 inode_dec_link_count(new_inode);
 315         } else {
 316                 if (dir_de) {
 317                         err = -EMLINK;
 318                         if (new_dir->i_nlink >= EXT2_LINK_MAX)
 319                                 goto out_dir;
 320                 }
 321                 inode_inc_link_count(old_inode);
 322                 err = ext2_add_link(new_dentry, old_inode);
 323                 if (err) {
 324                         inode_dec_link_count(old_inode);
 325                         goto out_dir;
 326                 }
 327                 if (dir_de)
 328                         inode_inc_link_count(new_dir);
 329         }
 330
 331         /*
 332          * Like most other Unix systems, set the ctime for inodes on a
 333          * rename.
 334          * inode_dec_link_count() will mark the inode dirty.
 335          */
 336         old_inode->i_ctime = CURRENT_TIME_SEC;
 337
 338         ext2_delete_entry (old_de, old_page);
 339         inode_dec_link_count(old_inode);
 340
 341         if (dir_de) {
 342                 ext2_set_link(old_inode, dir_de, dir_page, new_dir);
 343                 inode_dec_link_count(old_dir);
 344         }
 345         return 0;
 346
 347
 348 out_dir:
 349         if (dir_de) {
 350                 kunmap(dir_page);
 351                 page_cache_release(dir_page);
 352         }
 353 out_old:
 354         kunmap(old_page);
 355         page_cache_release(old_page);
 356 out:
 357         return err;
 358 }
 359
 360 const struct inode_operations ext2_dir_inode_operations = {
 361         .create         = ext2_create,
 362         .lookup         = ext2_lookup,
 363         .link           = ext2_link,
 364         .unlink         = ext2_unlink,
 365         .symlink        = ext2_symlink,
 366         .mkdir          = ext2_mkdir,
 367         .rmdir          = ext2_rmdir,
 368         .mknod          = ext2_mknod,
 369         .rename         = ext2_rename,
 370 #ifdef CONFIG_EXT2_FS_XATTR
 371         .setxattr       = generic_setxattr,
 372         .getxattr       = generic_getxattr,
 373         .listxattr      = ext2_listxattr,
 374         .removexattr    = generic_removexattr,
 375 #endif
 376         .setattr        = ext2_setattr,
 377         .permission     = ext2_permission,
 378 };
 379
 380 const struct inode_operations ext2_special_inode_operations = {
 381 #ifdef CONFIG_EXT2_FS_XATTR
 382         .setxattr       = generic_setxattr,
 383         .getxattr       = generic_getxattr,
 384         .listxattr      = ext2_listxattr,
 385         .removexattr    = generic_removexattr,
 386 #endif
 387         .setattr        = ext2_setattr,
 388         .permission     = ext2_permission,
 389 };