linux/fs/ext2/namei.c
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   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 <linux/quotaops.h>
  35#include "ext2.h"
  36#include "xattr.h"
  37#include "acl.h"
  38#include "xip.h"
  39
  40static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  41{
  42        int err = ext2_add_link(dentry, inode);
  43        if (!err) {
  44                unlock_new_inode(inode);
  45                d_instantiate(dentry, inode);
  46                return 0;
  47        }
  48        inode_dec_link_count(inode);
  49        unlock_new_inode(inode);
  50        iput(inode);
  51        return err;
  52}
  53
  54/*
  55 * Methods themselves.
  56 */
  57
  58static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
  59{
  60        struct inode * inode;
  61        ino_t ino;
  62        
  63        if (dentry->d_name.len > EXT2_NAME_LEN)
  64                return ERR_PTR(-ENAMETOOLONG);
  65
  66        ino = ext2_inode_by_name(dir, &dentry->d_name);
  67        inode = NULL;
  68        if (ino) {
  69                inode = ext2_iget(dir->i_sb, ino);
  70                if (inode == ERR_PTR(-ESTALE)) {
  71                        ext2_error(dir->i_sb, __func__,
  72                                        "deleted inode referenced: %lu",
  73                                        (unsigned long) ino);
  74                        return ERR_PTR(-EIO);
  75                }
  76        }
  77        return d_splice_alias(inode, dentry);
  78}
  79
  80struct dentry *ext2_get_parent(struct dentry *child)
  81{
  82        struct qstr dotdot = QSTR_INIT("..", 2);
  83        unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
  84        if (!ino)
  85                return ERR_PTR(-ENOENT);
  86        return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));
  87} 
  88
  89/*
  90 * By the time this is called, we already have created
  91 * the directory cache entry for the new file, but it
  92 * is so far negative - it has no inode.
  93 *
  94 * If the create succeeds, we fill in the inode information
  95 * with d_instantiate(). 
  96 */
  97static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
  98{
  99        struct inode *inode;
 100
 101        dquot_initialize(dir);
 102
 103        inode = ext2_new_inode(dir, mode, &dentry->d_name);
 104        if (IS_ERR(inode))
 105                return PTR_ERR(inode);
 106
 107        inode->i_op = &ext2_file_inode_operations;
 108        if (ext2_use_xip(inode->i_sb)) {
 109                inode->i_mapping->a_ops = &ext2_aops_xip;
 110                inode->i_fop = &ext2_xip_file_operations;
 111        } else if (test_opt(inode->i_sb, NOBH)) {
 112                inode->i_mapping->a_ops = &ext2_nobh_aops;
 113                inode->i_fop = &ext2_file_operations;
 114        } else {
 115                inode->i_mapping->a_ops = &ext2_aops;
 116                inode->i_fop = &ext2_file_operations;
 117        }
 118        mark_inode_dirty(inode);
 119        return ext2_add_nondir(dentry, inode);
 120}
 121
 122static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 123{
 124        struct inode * inode;
 125        int err;
 126
 127        if (!new_valid_dev(rdev))
 128                return -EINVAL;
 129
 130        dquot_initialize(dir);
 131
 132        inode = ext2_new_inode (dir, mode, &dentry->d_name);
 133        err = PTR_ERR(inode);
 134        if (!IS_ERR(inode)) {
 135                init_special_inode(inode, inode->i_mode, rdev);
 136#ifdef CONFIG_EXT2_FS_XATTR
 137                inode->i_op = &ext2_special_inode_operations;
 138#endif
 139                mark_inode_dirty(inode);
 140                err = ext2_add_nondir(dentry, inode);
 141        }
 142        return err;
 143}
 144
 145static int ext2_symlink (struct inode * dir, struct dentry * dentry,
 146        const char * symname)
 147{
 148        struct super_block * sb = dir->i_sb;
 149        int err = -ENAMETOOLONG;
 150        unsigned l = strlen(symname)+1;
 151        struct inode * inode;
 152
 153        if (l > sb->s_blocksize)
 154                goto out;
 155
 156        dquot_initialize(dir);
 157
 158        inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);
 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 = &ext2_symlink_inode_operations;
 166                if (test_opt(inode->i_sb, NOBH))
 167                        inode->i_mapping->a_ops = &ext2_nobh_aops;
 168                else
 169                        inode->i_mapping->a_ops = &ext2_aops;
 170                err = page_symlink(inode, symname, l);
 171                if (err)
 172                        goto out_fail;
 173        } else {
 174                /* fast symlink */
 175                inode->i_op = &ext2_fast_symlink_inode_operations;
 176                memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
 177                inode->i_size = l-1;
 178        }
 179        mark_inode_dirty(inode);
 180
 181        err = ext2_add_nondir(dentry, inode);
 182out:
 183        return err;
 184
 185out_fail:
 186        inode_dec_link_count(inode);
 187        unlock_new_inode(inode);
 188        iput (inode);
 189        goto out;
 190}
 191
 192static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 193        struct dentry *dentry)
 194{
 195        struct inode *inode = old_dentry->d_inode;
 196        int err;
 197
 198        dquot_initialize(dir);
 199
 200        inode->i_ctime = CURRENT_TIME_SEC;
 201        inode_inc_link_count(inode);
 202        ihold(inode);
 203
 204        err = ext2_add_link(dentry, inode);
 205        if (!err) {
 206                d_instantiate(dentry, inode);
 207                return 0;
 208        }
 209        inode_dec_link_count(inode);
 210        iput(inode);
 211        return err;
 212}
 213
 214static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 215{
 216        struct inode * inode;
 217        int err;
 218
 219        dquot_initialize(dir);
 220
 221        inode_inc_link_count(dir);
 222
 223        inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
 224        err = PTR_ERR(inode);
 225        if (IS_ERR(inode))
 226                goto out_dir;
 227
 228        inode->i_op = &ext2_dir_inode_operations;
 229        inode->i_fop = &ext2_dir_operations;
 230        if (test_opt(inode->i_sb, NOBH))
 231                inode->i_mapping->a_ops = &ext2_nobh_aops;
 232        else
 233                inode->i_mapping->a_ops = &ext2_aops;
 234
 235        inode_inc_link_count(inode);
 236
 237        err = ext2_make_empty(inode, dir);
 238        if (err)
 239                goto out_fail;
 240
 241        err = ext2_add_link(dentry, inode);
 242        if (err)
 243                goto out_fail;
 244
 245        unlock_new_inode(inode);
 246        d_instantiate(dentry, inode);
 247out:
 248        return err;
 249
 250out_fail:
 251        inode_dec_link_count(inode);
 252        inode_dec_link_count(inode);
 253        unlock_new_inode(inode);
 254        iput(inode);
 255out_dir:
 256        inode_dec_link_count(dir);
 257        goto out;
 258}
 259
 260static int ext2_unlink(struct inode * dir, struct dentry *dentry)
 261{
 262        struct inode * inode = dentry->d_inode;
 263        struct ext2_dir_entry_2 * de;
 264        struct page * page;
 265        int err = -ENOENT;
 266
 267        dquot_initialize(dir);
 268
 269        de = ext2_find_entry (dir, &dentry->d_name, &page);
 270        if (!de)
 271                goto out;
 272
 273        err = ext2_delete_entry (de, page);
 274        if (err)
 275                goto out;
 276
 277        inode->i_ctime = dir->i_ctime;
 278        inode_dec_link_count(inode);
 279        err = 0;
 280out:
 281        return err;
 282}
 283
 284static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 285{
 286        struct inode * inode = dentry->d_inode;
 287        int err = -ENOTEMPTY;
 288
 289        if (ext2_empty_dir(inode)) {
 290                err = ext2_unlink(dir, dentry);
 291                if (!err) {
 292                        inode->i_size = 0;
 293                        inode_dec_link_count(inode);
 294                        inode_dec_link_count(dir);
 295                }
 296        }
 297        return err;
 298}
 299
 300static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 301        struct inode * new_dir, struct dentry * new_dentry )
 302{
 303        struct inode * old_inode = old_dentry->d_inode;
 304        struct inode * new_inode = new_dentry->d_inode;
 305        struct page * dir_page = NULL;
 306        struct ext2_dir_entry_2 * dir_de = NULL;
 307        struct page * old_page;
 308        struct ext2_dir_entry_2 * old_de;
 309        int err = -ENOENT;
 310
 311        dquot_initialize(old_dir);
 312        dquot_initialize(new_dir);
 313
 314        old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);
 315        if (!old_de)
 316                goto out;
 317
 318        if (S_ISDIR(old_inode->i_mode)) {
 319                err = -EIO;
 320                dir_de = ext2_dotdot(old_inode, &dir_page);
 321                if (!dir_de)
 322                        goto out_old;
 323        }
 324
 325        if (new_inode) {
 326                struct page *new_page;
 327                struct ext2_dir_entry_2 *new_de;
 328
 329                err = -ENOTEMPTY;
 330                if (dir_de && !ext2_empty_dir (new_inode))
 331                        goto out_dir;
 332
 333                err = -ENOENT;
 334                new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);
 335                if (!new_de)
 336                        goto out_dir;
 337                ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
 338                new_inode->i_ctime = CURRENT_TIME_SEC;
 339                if (dir_de)
 340                        drop_nlink(new_inode);
 341                inode_dec_link_count(new_inode);
 342        } else {
 343                err = ext2_add_link(new_dentry, old_inode);
 344                if (err)
 345                        goto out_dir;
 346                if (dir_de)
 347                        inode_inc_link_count(new_dir);
 348        }
 349
 350        /*
 351         * Like most other Unix systems, set the ctime for inodes on a
 352         * rename.
 353         */
 354        old_inode->i_ctime = CURRENT_TIME_SEC;
 355        mark_inode_dirty(old_inode);
 356
 357        ext2_delete_entry (old_de, old_page);
 358
 359        if (dir_de) {
 360                if (old_dir != new_dir)
 361                        ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
 362                else {
 363                        kunmap(dir_page);
 364                        page_cache_release(dir_page);
 365                }
 366                inode_dec_link_count(old_dir);
 367        }
 368        return 0;
 369
 370
 371out_dir:
 372        if (dir_de) {
 373                kunmap(dir_page);
 374                page_cache_release(dir_page);
 375        }
 376out_old:
 377        kunmap(old_page);
 378        page_cache_release(old_page);
 379out:
 380        return err;
 381}
 382
 383const struct inode_operations ext2_dir_inode_operations = {
 384        .create         = ext2_create,
 385        .lookup         = ext2_lookup,
 386        .link           = ext2_link,
 387        .unlink         = ext2_unlink,
 388        .symlink        = ext2_symlink,
 389        .mkdir          = ext2_mkdir,
 390        .rmdir          = ext2_rmdir,
 391        .mknod          = ext2_mknod,
 392        .rename         = ext2_rename,
 393#ifdef CONFIG_EXT2_FS_XATTR
 394        .setxattr       = generic_setxattr,
 395        .getxattr       = generic_getxattr,
 396        .listxattr      = ext2_listxattr,
 397        .removexattr    = generic_removexattr,
 398#endif
 399        .setattr        = ext2_setattr,
 400        .get_acl        = ext2_get_acl,
 401};
 402
 403const struct inode_operations ext2_special_inode_operations = {
 404#ifdef CONFIG_EXT2_FS_XATTR
 405        .setxattr       = generic_setxattr,
 406        .getxattr       = generic_getxattr,
 407        .listxattr      = ext2_listxattr,
 408        .removexattr    = generic_removexattr,
 409#endif
 410        .setattr        = ext2_setattr,
 411        .get_acl        = ext2_get_acl,
 412};
 413
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