linux/fs/ubifs/tnc.c
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   1/*
   2 * This file is part of UBIFS.
   3 *
   4 * Copyright (C) 2006-2008 Nokia Corporation.
   5 *
   6 * This program is free software; you can redistribute it and/or modify it
   7 * under the terms of the GNU General Public License version 2 as published by
   8 * the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful, but WITHOUT
  11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13 * more details.
  14 *
  15 * You should have received a copy of the GNU General Public License along with
  16 * this program; if not, write to the Free Software Foundation, Inc., 51
  17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18 *
  19 * Authors: Adrian Hunter
  20 *          Artem Bityutskiy (Битюцкий Артём)
  21 */
  22
  23/*
  24 * This file implements TNC (Tree Node Cache) which caches indexing nodes of
  25 * the UBIFS B-tree.
  26 *
  27 * At the moment the locking rules of the TNC tree are quite simple and
  28 * straightforward. We just have a mutex and lock it when we traverse the
  29 * tree. If a znode is not in memory, we read it from flash while still having
  30 * the mutex locked.
  31 */
  32
  33#include <linux/crc32.h>
  34#include <linux/slab.h>
  35#include "ubifs.h"
  36
  37/*
  38 * Returned codes of 'matches_name()' and 'fallible_matches_name()' functions.
  39 * @NAME_LESS: name corresponding to the first argument is less than second
  40 * @NAME_MATCHES: names match
  41 * @NAME_GREATER: name corresponding to the second argument is greater than
  42 *                first
  43 * @NOT_ON_MEDIA: node referred by zbranch does not exist on the media
  44 *
  45 * These constants were introduce to improve readability.
  46 */
  47enum {
  48        NAME_LESS    = 0,
  49        NAME_MATCHES = 1,
  50        NAME_GREATER = 2,
  51        NOT_ON_MEDIA = 3,
  52};
  53
  54/**
  55 * insert_old_idx - record an index node obsoleted since the last commit start.
  56 * @c: UBIFS file-system description object
  57 * @lnum: LEB number of obsoleted index node
  58 * @offs: offset of obsoleted index node
  59 *
  60 * Returns %0 on success, and a negative error code on failure.
  61 *
  62 * For recovery, there must always be a complete intact version of the index on
  63 * flash at all times. That is called the "old index". It is the index as at the
  64 * time of the last successful commit. Many of the index nodes in the old index
  65 * may be dirty, but they must not be erased until the next successful commit
  66 * (at which point that index becomes the old index).
  67 *
  68 * That means that the garbage collection and the in-the-gaps method of
  69 * committing must be able to determine if an index node is in the old index.
  70 * Most of the old index nodes can be found by looking up the TNC using the
  71 * 'lookup_znode()' function. However, some of the old index nodes may have
  72 * been deleted from the current index or may have been changed so much that
  73 * they cannot be easily found. In those cases, an entry is added to an RB-tree.
  74 * That is what this function does. The RB-tree is ordered by LEB number and
  75 * offset because they uniquely identify the old index node.
  76 */
  77static int insert_old_idx(struct ubifs_info *c, int lnum, int offs)
  78{
  79        struct ubifs_old_idx *old_idx, *o;
  80        struct rb_node **p, *parent = NULL;
  81
  82        old_idx = kmalloc(sizeof(struct ubifs_old_idx), GFP_NOFS);
  83        if (unlikely(!old_idx))
  84                return -ENOMEM;
  85        old_idx->lnum = lnum;
  86        old_idx->offs = offs;
  87
  88        p = &c->old_idx.rb_node;
  89        while (*p) {
  90                parent = *p;
  91                o = rb_entry(parent, struct ubifs_old_idx, rb);
  92                if (lnum < o->lnum)
  93                        p = &(*p)->rb_left;
  94                else if (lnum > o->lnum)
  95                        p = &(*p)->rb_right;
  96                else if (offs < o->offs)
  97                        p = &(*p)->rb_left;
  98                else if (offs > o->offs)
  99                        p = &(*p)->rb_right;
 100                else {
 101                        ubifs_err("old idx added twice!");
 102                        kfree(old_idx);
 103                        return 0;
 104                }
 105        }
 106        rb_link_node(&old_idx->rb, parent, p);
 107        rb_insert_color(&old_idx->rb, &c->old_idx);
 108        return 0;
 109}
 110
 111/**
 112 * insert_old_idx_znode - record a znode obsoleted since last commit start.
 113 * @c: UBIFS file-system description object
 114 * @znode: znode of obsoleted index node
 115 *
 116 * Returns %0 on success, and a negative error code on failure.
 117 */
 118int insert_old_idx_znode(struct ubifs_info *c, struct ubifs_znode *znode)
 119{
 120        if (znode->parent) {
 121                struct ubifs_zbranch *zbr;
 122
 123                zbr = &znode->parent->zbranch[znode->iip];
 124                if (zbr->len)
 125                        return insert_old_idx(c, zbr->lnum, zbr->offs);
 126        } else
 127                if (c->zroot.len)
 128                        return insert_old_idx(c, c->zroot.lnum,
 129                                              c->zroot.offs);
 130        return 0;
 131}
 132
 133/**
 134 * ins_clr_old_idx_znode - record a znode obsoleted since last commit start.
 135 * @c: UBIFS file-system description object
 136 * @znode: znode of obsoleted index node
 137 *
 138 * Returns %0 on success, and a negative error code on failure.
 139 */
 140static int ins_clr_old_idx_znode(struct ubifs_info *c,
 141                                 struct ubifs_znode *znode)
 142{
 143        int err;
 144
 145        if (znode->parent) {
 146                struct ubifs_zbranch *zbr;
 147
 148                zbr = &znode->parent->zbranch[znode->iip];
 149                if (zbr->len) {
 150                        err = insert_old_idx(c, zbr->lnum, zbr->offs);
 151                        if (err)
 152                                return err;
 153                        zbr->lnum = 0;
 154                        zbr->offs = 0;
 155                        zbr->len = 0;
 156                }
 157        } else
 158                if (c->zroot.len) {
 159                        err = insert_old_idx(c, c->zroot.lnum, c->zroot.offs);
 160                        if (err)
 161                                return err;
 162                        c->zroot.lnum = 0;
 163                        c->zroot.offs = 0;
 164                        c->zroot.len = 0;
 165                }
 166        return 0;
 167}
 168
 169/**
 170 * destroy_old_idx - destroy the old_idx RB-tree.
 171 * @c: UBIFS file-system description object
 172 *
 173 * During start commit, the old_idx RB-tree is used to avoid overwriting index
 174 * nodes that were in the index last commit but have since been deleted.  This
 175 * is necessary for recovery i.e. the old index must be kept intact until the
 176 * new index is successfully written.  The old-idx RB-tree is used for the
 177 * in-the-gaps method of writing index nodes and is destroyed every commit.
 178 */
 179void destroy_old_idx(struct ubifs_info *c)
 180{
 181        struct rb_node *this = c->old_idx.rb_node;
 182        struct ubifs_old_idx *old_idx;
 183
 184        while (this) {
 185                if (this->rb_left) {
 186                        this = this->rb_left;
 187                        continue;
 188                } else if (this->rb_right) {
 189                        this = this->rb_right;
 190                        continue;
 191                }
 192                old_idx = rb_entry(this, struct ubifs_old_idx, rb);
 193                this = rb_parent(this);
 194                if (this) {
 195                        if (this->rb_left == &old_idx->rb)
 196                                this->rb_left = NULL;
 197                        else
 198                                this->rb_right = NULL;
 199                }
 200                kfree(old_idx);
 201        }
 202        c->old_idx = RB_ROOT;
 203}
 204
 205/**
 206 * copy_znode - copy a dirty znode.
 207 * @c: UBIFS file-system description object
 208 * @znode: znode to copy
 209 *
 210 * A dirty znode being committed may not be changed, so it is copied.
 211 */
 212static struct ubifs_znode *copy_znode(struct ubifs_info *c,
 213                                      struct ubifs_znode *znode)
 214{
 215        struct ubifs_znode *zn;
 216
 217        zn = kmalloc(c->max_znode_sz, GFP_NOFS);
 218        if (unlikely(!zn))
 219                return ERR_PTR(-ENOMEM);
 220
 221        memcpy(zn, znode, c->max_znode_sz);
 222        zn->cnext = NULL;
 223        __set_bit(DIRTY_ZNODE, &zn->flags);
 224        __clear_bit(COW_ZNODE, &zn->flags);
 225
 226        ubifs_assert(!ubifs_zn_obsolete(znode));
 227        __set_bit(OBSOLETE_ZNODE, &znode->flags);
 228
 229        if (znode->level != 0) {
 230                int i;
 231                const int n = zn->child_cnt;
 232
 233                /* The children now have new parent */
 234                for (i = 0; i < n; i++) {
 235                        struct ubifs_zbranch *zbr = &zn->zbranch[i];
 236
 237                        if (zbr->znode)
 238                                zbr->znode->parent = zn;
 239                }
 240        }
 241
 242        atomic_long_inc(&c->dirty_zn_cnt);
 243        return zn;
 244}
 245
 246/**
 247 * add_idx_dirt - add dirt due to a dirty znode.
 248 * @c: UBIFS file-system description object
 249 * @lnum: LEB number of index node
 250 * @dirt: size of index node
 251 *
 252 * This function updates lprops dirty space and the new size of the index.
 253 */
 254static int add_idx_dirt(struct ubifs_info *c, int lnum, int dirt)
 255{
 256        c->calc_idx_sz -= ALIGN(dirt, 8);
 257        return ubifs_add_dirt(c, lnum, dirt);
 258}
 259
 260/**
 261 * dirty_cow_znode - ensure a znode is not being committed.
 262 * @c: UBIFS file-system description object
 263 * @zbr: branch of znode to check
 264 *
 265 * Returns dirtied znode on success or negative error code on failure.
 266 */
 267static struct ubifs_znode *dirty_cow_znode(struct ubifs_info *c,
 268                                           struct ubifs_zbranch *zbr)
 269{
 270        struct ubifs_znode *znode = zbr->znode;
 271        struct ubifs_znode *zn;
 272        int err;
 273
 274        if (!ubifs_zn_cow(znode)) {
 275                /* znode is not being committed */
 276                if (!test_and_set_bit(DIRTY_ZNODE, &znode->flags)) {
 277                        atomic_long_inc(&c->dirty_zn_cnt);
 278                        atomic_long_dec(&c->clean_zn_cnt);
 279                        atomic_long_dec(&ubifs_clean_zn_cnt);
 280                        err = add_idx_dirt(c, zbr->lnum, zbr->len);
 281                        if (unlikely(err))
 282                                return ERR_PTR(err);
 283                }
 284                return znode;
 285        }
 286
 287        zn = copy_znode(c, znode);
 288        if (IS_ERR(zn))
 289                return zn;
 290
 291        if (zbr->len) {
 292                err = insert_old_idx(c, zbr->lnum, zbr->offs);
 293                if (unlikely(err))
 294                        return ERR_PTR(err);
 295                err = add_idx_dirt(c, zbr->lnum, zbr->len);
 296        } else
 297                err = 0;
 298
 299        zbr->znode = zn;
 300        zbr->lnum = 0;
 301        zbr->offs = 0;
 302        zbr->len = 0;
 303
 304        if (unlikely(err))
 305                return ERR_PTR(err);
 306        return zn;
 307}
 308
 309/**
 310 * lnc_add - add a leaf node to the leaf node cache.
 311 * @c: UBIFS file-system description object
 312 * @zbr: zbranch of leaf node
 313 * @node: leaf node
 314 *
 315 * Leaf nodes are non-index nodes directory entry nodes or data nodes. The
 316 * purpose of the leaf node cache is to save re-reading the same leaf node over
 317 * and over again. Most things are cached by VFS, however the file system must
 318 * cache directory entries for readdir and for resolving hash collisions. The
 319 * present implementation of the leaf node cache is extremely simple, and
 320 * allows for error returns that are not used but that may be needed if a more
 321 * complex implementation is created.
 322 *
 323 * Note, this function does not add the @node object to LNC directly, but
 324 * allocates a copy of the object and adds the copy to LNC. The reason for this
 325 * is that @node has been allocated outside of the TNC subsystem and will be
 326 * used with @c->tnc_mutex unlock upon return from the TNC subsystem. But LNC
 327 * may be changed at any time, e.g. freed by the shrinker.
 328 */
 329static int lnc_add(struct ubifs_info *c, struct ubifs_zbranch *zbr,
 330                   const void *node)
 331{
 332        int err;
 333        void *lnc_node;
 334        const struct ubifs_dent_node *dent = node;
 335
 336        ubifs_assert(!zbr->leaf);
 337        ubifs_assert(zbr->len != 0);
 338        ubifs_assert(is_hash_key(c, &zbr->key));
 339
 340        err = ubifs_validate_entry(c, dent);
 341        if (err) {
 342                dump_stack();
 343                ubifs_dump_node(c, dent);
 344                return err;
 345        }
 346
 347        lnc_node = kmemdup(node, zbr->len, GFP_NOFS);
 348        if (!lnc_node)
 349                /* We don't have to have the cache, so no error */
 350                return 0;
 351
 352        zbr->leaf = lnc_node;
 353        return 0;
 354}
 355
 356 /**
 357 * lnc_add_directly - add a leaf node to the leaf-node-cache.
 358 * @c: UBIFS file-system description object
 359 * @zbr: zbranch of leaf node
 360 * @node: leaf node
 361 *
 362 * This function is similar to 'lnc_add()', but it does not create a copy of
 363 * @node but inserts @node to TNC directly.
 364 */
 365static int lnc_add_directly(struct ubifs_info *c, struct ubifs_zbranch *zbr,
 366                            void *node)
 367{
 368        int err;
 369
 370        ubifs_assert(!zbr->leaf);
 371        ubifs_assert(zbr->len != 0);
 372
 373        err = ubifs_validate_entry(c, node);
 374        if (err) {
 375                dump_stack();
 376                ubifs_dump_node(c, node);
 377                return err;
 378        }
 379
 380        zbr->leaf = node;
 381        return 0;
 382}
 383
 384/**
 385 * lnc_free - remove a leaf node from the leaf node cache.
 386 * @zbr: zbranch of leaf node
 387 * @node: leaf node
 388 */
 389static void lnc_free(struct ubifs_zbranch *zbr)
 390{
 391        if (!zbr->leaf)
 392                return;
 393        kfree(zbr->leaf);
 394        zbr->leaf = NULL;
 395}
 396
 397/**
 398 * tnc_read_node_nm - read a "hashed" leaf node.
 399 * @c: UBIFS file-system description object
 400 * @zbr: key and position of the node
 401 * @node: node is returned here
 402 *
 403 * This function reads a "hashed" node defined by @zbr from the leaf node cache
 404 * (in it is there) or from the hash media, in which case the node is also
 405 * added to LNC. Returns zero in case of success or a negative negative error
 406 * code in case of failure.
 407 */
 408static int tnc_read_node_nm(struct ubifs_info *c, struct ubifs_zbranch *zbr,
 409                            void *node)
 410{
 411        int err;
 412
 413        ubifs_assert(is_hash_key(c, &zbr->key));
 414
 415        if (zbr->leaf) {
 416                /* Read from the leaf node cache */
 417                ubifs_assert(zbr->len != 0);
 418                memcpy(node, zbr->leaf, zbr->len);
 419                return 0;
 420        }
 421
 422        err = ubifs_tnc_read_node(c, zbr, node);
 423        if (err)
 424                return err;
 425
 426        /* Add the node to the leaf node cache */
 427        err = lnc_add(c, zbr, node);
 428        return err;
 429}
 430
 431/**
 432 * try_read_node - read a node if it is a node.
 433 * @c: UBIFS file-system description object
 434 * @buf: buffer to read to
 435 * @type: node type
 436 * @len: node length (not aligned)
 437 * @lnum: LEB number of node to read
 438 * @offs: offset of node to read
 439 *
 440 * This function tries to read a node of known type and length, checks it and
 441 * stores it in @buf. This function returns %1 if a node is present and %0 if
 442 * a node is not present. A negative error code is returned for I/O errors.
 443 * This function performs that same function as ubifs_read_node except that
 444 * it does not require that there is actually a node present and instead
 445 * the return code indicates if a node was read.
 446 *
 447 * Note, this function does not check CRC of data nodes if @c->no_chk_data_crc
 448 * is true (it is controlled by corresponding mount option). However, if
 449 * @c->mounting or @c->remounting_rw is true (we are mounting or re-mounting to
 450 * R/W mode), @c->no_chk_data_crc is ignored and CRC is checked. This is
 451 * because during mounting or re-mounting from R/O mode to R/W mode we may read
 452 * journal nodes (when replying the journal or doing the recovery) and the
 453 * journal nodes may potentially be corrupted, so checking is required.
 454 */
 455static int try_read_node(const struct ubifs_info *c, void *buf, int type,
 456                         int len, int lnum, int offs)
 457{
 458        int err, node_len;
 459        struct ubifs_ch *ch = buf;
 460        uint32_t crc, node_crc;
 461
 462        dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
 463
 464        err = ubifs_leb_read(c, lnum, buf, offs, len, 1);
 465        if (err) {
 466                ubifs_err("cannot read node type %d from LEB %d:%d, error %d",
 467                          type, lnum, offs, err);
 468                return err;
 469        }
 470
 471        if (le32_to_cpu(ch->magic) != UBIFS_NODE_MAGIC)
 472                return 0;
 473
 474        if (ch->node_type != type)
 475                return 0;
 476
 477        node_len = le32_to_cpu(ch->len);
 478        if (node_len != len)
 479                return 0;
 480
 481        if (type == UBIFS_DATA_NODE && c->no_chk_data_crc && !c->mounting &&
 482            !c->remounting_rw)
 483                return 1;
 484
 485        crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
 486        node_crc = le32_to_cpu(ch->crc);
 487        if (crc != node_crc)
 488                return 0;
 489
 490        return 1;
 491}
 492
 493/**
 494 * fallible_read_node - try to read a leaf node.
 495 * @c: UBIFS file-system description object
 496 * @key:  key of node to read
 497 * @zbr:  position of node
 498 * @node: node returned
 499 *
 500 * This function tries to read a node and returns %1 if the node is read, %0
 501 * if the node is not present, and a negative error code in the case of error.
 502 */
 503static int fallible_read_node(struct ubifs_info *c, const union ubifs_key *key,
 504                              struct ubifs_zbranch *zbr, void *node)
 505{
 506        int ret;
 507
 508        dbg_tnck(key, "LEB %d:%d, key ", zbr->lnum, zbr->offs);
 509
 510        ret = try_read_node(c, node, key_type(c, key), zbr->len, zbr->lnum,
 511                            zbr->offs);
 512        if (ret == 1) {
 513                union ubifs_key node_key;
 514                struct ubifs_dent_node *dent = node;
 515
 516                /* All nodes have key in the same place */
 517                key_read(c, &dent->key, &node_key);
 518                if (keys_cmp(c, key, &node_key) != 0)
 519                        ret = 0;
 520        }
 521        if (ret == 0 && c->replaying)
 522                dbg_mntk(key, "dangling branch LEB %d:%d len %d, key ",
 523                        zbr->lnum, zbr->offs, zbr->len);
 524        return ret;
 525}
 526
 527/**
 528 * matches_name - determine if a direntry or xattr entry matches a given name.
 529 * @c: UBIFS file-system description object
 530 * @zbr: zbranch of dent
 531 * @nm: name to match
 532 *
 533 * This function checks if xentry/direntry referred by zbranch @zbr matches name
 534 * @nm. Returns %NAME_MATCHES if it does, %NAME_LESS if the name referred by
 535 * @zbr is less than @nm, and %NAME_GREATER if it is greater than @nm. In case
 536 * of failure, a negative error code is returned.
 537 */
 538static int matches_name(struct ubifs_info *c, struct ubifs_zbranch *zbr,
 539                        const struct qstr *nm)
 540{
 541        struct ubifs_dent_node *dent;
 542        int nlen, err;
 543
 544        /* If possible, match against the dent in the leaf node cache */
 545        if (!zbr->leaf) {
 546                dent = kmalloc(zbr->len, GFP_NOFS);
 547                if (!dent)
 548                        return -ENOMEM;
 549
 550                err = ubifs_tnc_read_node(c, zbr, dent);
 551                if (err)
 552                        goto out_free;
 553
 554                /* Add the node to the leaf node cache */
 555                err = lnc_add_directly(c, zbr, dent);
 556                if (err)
 557                        goto out_free;
 558        } else
 559                dent = zbr->leaf;
 560
 561        nlen = le16_to_cpu(dent->nlen);
 562        err = memcmp(dent->name, nm->name, min_t(int, nlen, nm->len));
 563        if (err == 0) {
 564                if (nlen == nm->len)
 565                        return NAME_MATCHES;
 566                else if (nlen < nm->len)
 567                        return NAME_LESS;
 568                else
 569                        return NAME_GREATER;
 570        } else if (err < 0)
 571                return NAME_LESS;
 572        else
 573                return NAME_GREATER;
 574
 575out_free:
 576        kfree(dent);
 577        return err;
 578}
 579
 580/**
 581 * get_znode - get a TNC znode that may not be loaded yet.
 582 * @c: UBIFS file-system description object
 583 * @znode: parent znode
 584 * @n: znode branch slot number
 585 *
 586 * This function returns the znode or a negative error code.
 587 */
 588static struct ubifs_znode *get_znode(struct ubifs_info *c,
 589                                     struct ubifs_znode *znode, int n)
 590{
 591        struct ubifs_zbranch *zbr;
 592
 593        zbr = &znode->zbranch[n];
 594        if (zbr->znode)
 595                znode = zbr->znode;
 596        else
 597                znode = ubifs_load_znode(c, zbr, znode, n);
 598        return znode;
 599}
 600
 601/**
 602 * tnc_next - find next TNC entry.
 603 * @c: UBIFS file-system description object
 604 * @zn: znode is passed and returned here
 605 * @n: znode branch slot number is passed and returned here
 606 *
 607 * This function returns %0 if the next TNC entry is found, %-ENOENT if there is
 608 * no next entry, or a negative error code otherwise.
 609 */
 610static int tnc_next(struct ubifs_info *c, struct ubifs_znode **zn, int *n)
 611{
 612        struct ubifs_znode *znode = *zn;
 613        int nn = *n;
 614
 615        nn += 1;
 616        if (nn < znode->child_cnt) {
 617                *n = nn;
 618                return 0;
 619        }
 620        while (1) {
 621                struct ubifs_znode *zp;
 622
 623                zp = znode->parent;
 624                if (!zp)
 625                        return -ENOENT;
 626                nn = znode->iip + 1;
 627                znode = zp;
 628                if (nn < znode->child_cnt) {
 629                        znode = get_znode(c, znode, nn);
 630                        if (IS_ERR(znode))
 631                                return PTR_ERR(znode);
 632                        while (znode->level != 0) {
 633                                znode = get_znode(c, znode, 0);
 634                                if (IS_ERR(znode))
 635                                        return PTR_ERR(znode);
 636                        }
 637                        nn = 0;
 638                        break;
 639                }
 640        }
 641        *zn = znode;
 642        *n = nn;
 643        return 0;
 644}
 645
 646/**
 647 * tnc_prev - find previous TNC entry.
 648 * @c: UBIFS file-system description object
 649 * @zn: znode is returned here
 650 * @n: znode branch slot number is passed and returned here
 651 *
 652 * This function returns %0 if the previous TNC entry is found, %-ENOENT if
 653 * there is no next entry, or a negative error code otherwise.
 654 */
 655static int tnc_prev(struct ubifs_info *c, struct ubifs_znode **zn, int *n)
 656{
 657        struct ubifs_znode *znode = *zn;
 658        int nn = *n;
 659
 660        if (nn > 0) {
 661                *n = nn - 1;
 662                return 0;
 663        }
 664        while (1) {
 665                struct ubifs_znode *zp;
 666
 667                zp = znode->parent;
 668                if (!zp)
 669                        return -ENOENT;
 670                nn = znode->iip - 1;
 671                znode = zp;
 672                if (nn >= 0) {
 673                        znode = get_znode(c, znode, nn);
 674                        if (IS_ERR(znode))
 675                                return PTR_ERR(znode);
 676                        while (znode->level != 0) {
 677                                nn = znode->child_cnt - 1;
 678                                znode = get_znode(c, znode, nn);
 679                                if (IS_ERR(znode))
 680                                        return PTR_ERR(znode);
 681                        }
 682                        nn = znode->child_cnt - 1;
 683                        break;
 684                }
 685        }
 686        *zn = znode;
 687        *n = nn;
 688        return 0;
 689}
 690
 691/**
 692 * resolve_collision - resolve a collision.
 693 * @c: UBIFS file-system description object
 694 * @key: key of a directory or extended attribute entry
 695 * @zn: znode is returned here
 696 * @n: zbranch number is passed and returned here
 697 * @nm: name of the entry
 698 *
 699 * This function is called for "hashed" keys to make sure that the found key
 700 * really corresponds to the looked up node (directory or extended attribute
 701 * entry). It returns %1 and sets @zn and @n if the collision is resolved.
 702 * %0 is returned if @nm is not found and @zn and @n are set to the previous
 703 * entry, i.e. to the entry after which @nm could follow if it were in TNC.
 704 * This means that @n may be set to %-1 if the leftmost key in @zn is the
 705 * previous one. A negative error code is returned on failures.
 706 */
 707static int resolve_collision(struct ubifs_info *c, const union ubifs_key *key,
 708                             struct ubifs_znode **zn, int *n,
 709                             const struct qstr *nm)
 710{
 711        int err;
 712
 713        err = matches_name(c, &(*zn)->zbranch[*n], nm);
 714        if (unlikely(err < 0))
 715                return err;
 716        if (err == NAME_MATCHES)
 717                return 1;
 718
 719        if (err == NAME_GREATER) {
 720                /* Look left */
 721                while (1) {
 722                        err = tnc_prev(c, zn, n);
 723                        if (err == -ENOENT) {
 724                                ubifs_assert(*n == 0);
 725                                *n = -1;
 726                                return 0;
 727                        }
 728                        if (err < 0)
 729                                return err;
 730                        if (keys_cmp(c, &(*zn)->zbranch[*n].key, key)) {
 731                                /*
 732                                 * We have found the branch after which we would
 733                                 * like to insert, but inserting in this znode
 734                                 * may still be wrong. Consider the following 3
 735                                 * znodes, in the case where we are resolving a
 736                                 * collision with Key2.
 737                                 *
 738                                 *                  znode zp
 739                                 *            ----------------------
 740                                 * level 1     |  Key0  |  Key1  |
 741                                 *            -----------------------
 742                                 *                 |            |
 743                                 *       znode za  |            |  znode zb
 744                                 *          ------------      ------------
 745                                 * level 0  |  Key0  |        |  Key2  |
 746                                 *          ------------      ------------
 747                                 *
 748                                 * The lookup finds Key2 in znode zb. Lets say
 749                                 * there is no match and the name is greater so
 750                                 * we look left. When we find Key0, we end up
 751                                 * here. If we return now, we will insert into
 752                                 * znode za at slot n = 1.  But that is invalid
 753                                 * according to the parent's keys.  Key2 must
 754                                 * be inserted into znode zb.
 755                                 *
 756                                 * Note, this problem is not relevant for the
 757                                 * case when we go right, because
 758                                 * 'tnc_insert()' would correct the parent key.
 759                                 */
 760                                if (*n == (*zn)->child_cnt - 1) {
 761                                        err = tnc_next(c, zn, n);
 762                                        if (err) {
 763                                                /* Should be impossible */
 764                                                ubifs_assert(0);
 765                                                if (err == -ENOENT)
 766                                                        err = -EINVAL;
 767                                                return err;
 768                                        }
 769                                        ubifs_assert(*n == 0);
 770                                        *n = -1;
 771                                }
 772                                return 0;
 773                        }
 774                        err = matches_name(c, &(*zn)->zbranch[*n], nm);
 775                        if (err < 0)
 776                                return err;
 777                        if (err == NAME_LESS)
 778                                return 0;
 779                        if (err == NAME_MATCHES)
 780                                return 1;
 781                        ubifs_assert(err == NAME_GREATER);
 782                }
 783        } else {
 784                int nn = *n;
 785                struct ubifs_znode *znode = *zn;
 786
 787                /* Look right */
 788                while (1) {
 789                        err = tnc_next(c, &znode, &nn);
 790                        if (err == -ENOENT)
 791                                return 0;
 792                        if (err < 0)
 793                                return err;
 794                        if (keys_cmp(c, &znode->zbranch[nn].key, key))
 795                                return 0;
 796                        err = matches_name(c, &znode->zbranch[nn], nm);
 797                        if (err < 0)
 798                                return err;
 799                        if (err == NAME_GREATER)
 800                                return 0;
 801                        *zn = znode;
 802                        *n = nn;
 803                        if (err == NAME_MATCHES)
 804                                return 1;
 805                        ubifs_assert(err == NAME_LESS);
 806                }
 807        }
 808}
 809
 810/**
 811 * fallible_matches_name - determine if a dent matches a given name.
 812 * @c: UBIFS file-system description object
 813 * @zbr: zbranch of dent
 814 * @nm: name to match
 815 *
 816 * This is a "fallible" version of 'matches_name()' function which does not
 817 * panic if the direntry/xentry referred by @zbr does not exist on the media.
 818 *
 819 * This function checks if xentry/direntry referred by zbranch @zbr matches name
 820 * @nm. Returns %NAME_MATCHES it does, %NAME_LESS if the name referred by @zbr
 821 * is less than @nm, %NAME_GREATER if it is greater than @nm, and @NOT_ON_MEDIA
 822 * if xentry/direntry referred by @zbr does not exist on the media. A negative
 823 * error code is returned in case of failure.
 824 */
 825static int fallible_matches_name(struct ubifs_info *c,
 826                                 struct ubifs_zbranch *zbr,
 827                                 const struct qstr *nm)
 828{
 829        struct ubifs_dent_node *dent;
 830        int nlen, err;
 831
 832        /* If possible, match against the dent in the leaf node cache */
 833        if (!zbr->leaf) {
 834                dent = kmalloc(zbr->len, GFP_NOFS);
 835                if (!dent)
 836                        return -ENOMEM;
 837
 838                err = fallible_read_node(c, &zbr->key, zbr, dent);
 839                if (err < 0)
 840                        goto out_free;
 841                if (err == 0) {
 842                        /* The node was not present */
 843                        err = NOT_ON_MEDIA;
 844                        goto out_free;
 845                }
 846                ubifs_assert(err == 1);
 847
 848                err = lnc_add_directly(c, zbr, dent);
 849                if (err)
 850                        goto out_free;
 851        } else
 852                dent = zbr->leaf;
 853
 854        nlen = le16_to_cpu(dent->nlen);
 855        err = memcmp(dent->name, nm->name, min_t(int, nlen, nm->len));
 856        if (err == 0) {
 857                if (nlen == nm->len)
 858                        return NAME_MATCHES;
 859                else if (nlen < nm->len)
 860                        return NAME_LESS;
 861                else
 862                        return NAME_GREATER;
 863        } else if (err < 0)
 864                return NAME_LESS;
 865        else
 866                return NAME_GREATER;
 867
 868out_free:
 869        kfree(dent);
 870        return err;
 871}
 872
 873/**
 874 * fallible_resolve_collision - resolve a collision even if nodes are missing.
 875 * @c: UBIFS file-system description object
 876 * @key: key
 877 * @zn: znode is returned here
 878 * @n: branch number is passed and returned here
 879 * @nm: name of directory entry
 880 * @adding: indicates caller is adding a key to the TNC
 881 *
 882 * This is a "fallible" version of the 'resolve_collision()' function which
 883 * does not panic if one of the nodes referred to by TNC does not exist on the
 884 * media. This may happen when replaying the journal if a deleted node was
 885 * Garbage-collected and the commit was not done. A branch that refers to a node
 886 * that is not present is called a dangling branch. The following are the return
 887 * codes for this function:
 888 *  o if @nm was found, %1 is returned and @zn and @n are set to the found
 889 *    branch;
 890 *  o if we are @adding and @nm was not found, %0 is returned;
 891 *  o if we are not @adding and @nm was not found, but a dangling branch was
 892 *    found, then %1 is returned and @zn and @n are set to the dangling branch;
 893 *  o a negative error code is returned in case of failure.
 894 */
 895static int fallible_resolve_collision(struct ubifs_info *c,
 896                                      const union ubifs_key *key,
 897                                      struct ubifs_znode **zn, int *n,
 898                                      const struct qstr *nm, int adding)
 899{
 900        struct ubifs_znode *o_znode = NULL, *znode = *zn;
 901        int uninitialized_var(o_n), err, cmp, unsure = 0, nn = *n;
 902
 903        cmp = fallible_matches_name(c, &znode->zbranch[nn], nm);
 904        if (unlikely(cmp < 0))
 905                return cmp;
 906        if (cmp == NAME_MATCHES)
 907                return 1;
 908        if (cmp == NOT_ON_MEDIA) {
 909                o_znode = znode;
 910                o_n = nn;
 911                /*
 912                 * We are unlucky and hit a dangling branch straight away.
 913                 * Now we do not really know where to go to find the needed
 914                 * branch - to the left or to the right. Well, let's try left.
 915                 */
 916                unsure = 1;
 917        } else if (!adding)
 918                unsure = 1; /* Remove a dangling branch wherever it is */
 919
 920        if (cmp == NAME_GREATER || unsure) {
 921                /* Look left */
 922                while (1) {
 923                        err = tnc_prev(c, zn, n);
 924                        if (err == -ENOENT) {
 925                                ubifs_assert(*n == 0);
 926                                *n = -1;
 927                                break;
 928                        }
 929                        if (err < 0)
 930                                return err;
 931                        if (keys_cmp(c, &(*zn)->zbranch[*n].key, key)) {
 932                                /* See comments in 'resolve_collision()' */
 933                                if (*n == (*zn)->child_cnt - 1) {
 934                                        err = tnc_next(c, zn, n);
 935                                        if (err) {
 936                                                /* Should be impossible */
 937                                                ubifs_assert(0);
 938                                                if (err == -ENOENT)
 939                                                        err = -EINVAL;
 940                                                return err;
 941                                        }
 942                                        ubifs_assert(*n == 0);
 943                                        *n = -1;
 944                                }
 945                                break;
 946                        }
 947                        err = fallible_matches_name(c, &(*zn)->zbranch[*n], nm);
 948                        if (err < 0)
 949                                return err;
 950                        if (err == NAME_MATCHES)
 951                                return 1;
 952                        if (err == NOT_ON_MEDIA) {
 953                                o_znode = *zn;
 954                                o_n = *n;
 955                                continue;
 956                        }
 957                        if (!adding)
 958                                continue;
 959                        if (err == NAME_LESS)
 960                                break;
 961                        else
 962                                unsure = 0;
 963                }
 964        }
 965
 966        if (cmp == NAME_LESS || unsure) {
 967                /* Look right */
 968                *zn = znode;
 969                *n = nn;
 970                while (1) {
 971                        err = tnc_next(c, &znode, &nn);
 972                        if (err == -ENOENT)
 973                                break;
 974                        if (err < 0)
 975                                return err;
 976                        if (keys_cmp(c, &znode->zbranch[nn].key, key))
 977                                break;
 978                        err = fallible_matches_name(c, &znode->zbranch[nn], nm);
 979                        if (err < 0)
 980                                return err;
 981                        if (err == NAME_GREATER)
 982                                break;
 983                        *zn = znode;
 984                        *n = nn;
 985                        if (err == NAME_MATCHES)
 986                                return 1;
 987                        if (err == NOT_ON_MEDIA) {
 988                                o_znode = znode;
 989                                o_n = nn;
 990                        }
 991                }
 992        }
 993
 994        /* Never match a dangling branch when adding */
 995        if (adding || !o_znode)
 996                return 0;
 997
 998        dbg_mntk(key, "dangling match LEB %d:%d len %d key ",
 999                o_znode->zbranch[o_n].lnum, o_znode->zbranch[o_n].offs,
1000                o_znode->zbranch[o_n].len);
1001        *zn = o_znode;
1002        *n = o_n;
1003        return 1;
1004}
1005
1006/**
1007 * matches_position - determine if a zbranch matches a given position.
1008 * @zbr: zbranch of dent
1009 * @lnum: LEB number of dent to match
1010 * @offs: offset of dent to match
1011 *
1012 * This function returns %1 if @lnum:@offs matches, and %0 otherwise.
1013 */
1014static int matches_position(struct ubifs_zbranch *zbr, int lnum, int offs)
1015{
1016        if (zbr->lnum == lnum && zbr->offs == offs)
1017                return 1;
1018        else
1019                return 0;
1020}
1021
1022/**
1023 * resolve_collision_directly - resolve a collision directly.
1024 * @c: UBIFS file-system description object
1025 * @key: key of directory entry
1026 * @zn: znode is passed and returned here
1027 * @n: zbranch number is passed and returned here
1028 * @lnum: LEB number of dent node to match
1029 * @offs: offset of dent node to match
1030 *
1031 * This function is used for "hashed" keys to make sure the found directory or
1032 * extended attribute entry node is what was looked for. It is used when the
1033 * flash address of the right node is known (@lnum:@offs) which makes it much
1034 * easier to resolve collisions (no need to read entries and match full
1035 * names). This function returns %1 and sets @zn and @n if the collision is
1036 * resolved, %0 if @lnum:@offs is not found and @zn and @n are set to the
1037 * previous directory entry. Otherwise a negative error code is returned.
1038 */
1039static int resolve_collision_directly(struct ubifs_info *c,
1040                                      const union ubifs_key *key,
1041                                      struct ubifs_znode **zn, int *n,
1042                                      int lnum, int offs)
1043{
1044        struct ubifs_znode *znode;
1045        int nn, err;
1046
1047        znode = *zn;
1048        nn = *n;
1049        if (matches_position(&znode->zbranch[nn], lnum, offs))
1050                return 1;
1051
1052        /* Look left */
1053        while (1) {
1054                err = tnc_prev(c, &znode, &nn);
1055                if (err == -ENOENT)
1056                        break;
1057                if (err < 0)
1058                        return err;
1059                if (keys_cmp(c, &znode->zbranch[nn].key, key))
1060                        break;
1061                if (matches_position(&znode->zbranch[nn], lnum, offs)) {
1062                        *zn = znode;
1063                        *n = nn;
1064                        return 1;
1065                }
1066        }
1067
1068        /* Look right */
1069        znode = *zn;
1070        nn = *n;
1071        while (1) {
1072                err = tnc_next(c, &znode, &nn);
1073                if (err == -ENOENT)
1074                        return 0;
1075                if (err < 0)
1076                        return err;
1077                if (keys_cmp(c, &znode->zbranch[nn].key, key))
1078                        return 0;
1079                *zn = znode;
1080                *n = nn;
1081                if (matches_position(&znode->zbranch[nn], lnum, offs))
1082                        return 1;
1083        }
1084}
1085
1086/**
1087 * dirty_cow_bottom_up - dirty a znode and its ancestors.
1088 * @c: UBIFS file-system description object
1089 * @znode: znode to dirty
1090 *
1091 * If we do not have a unique key that resides in a znode, then we cannot
1092 * dirty that znode from the top down (i.e. by using lookup_level0_dirty)
1093 * This function records the path back to the last dirty ancestor, and then
1094 * dirties the znodes on that path.
1095 */
1096static struct ubifs_znode *dirty_cow_bottom_up(struct ubifs_info *c,
1097                                               struct ubifs_znode *znode)
1098{
1099        struct ubifs_znode *zp;
1100        int *path = c->bottom_up_buf, p = 0;
1101
1102        ubifs_assert(c->zroot.znode);
1103        ubifs_assert(znode);
1104        if (c->zroot.znode->level > BOTTOM_UP_HEIGHT) {
1105                kfree(c->bottom_up_buf);
1106                c->bottom_up_buf = kmalloc(c->zroot.znode->level * sizeof(int),
1107                                           GFP_NOFS);
1108                if (!c->bottom_up_buf)
1109                        return ERR_PTR(-ENOMEM);
1110                path = c->bottom_up_buf;
1111        }
1112        if (c->zroot.znode->level) {
1113                /* Go up until parent is dirty */
1114                while (1) {
1115                        int n;
1116
1117                        zp = znode->parent;
1118                        if (!zp)
1119                                break;
1120                        n = znode->iip;
1121                        ubifs_assert(p < c->zroot.znode->level);
1122                        path[p++] = n;
1123                        if (!zp->cnext && ubifs_zn_dirty(znode))
1124                                break;
1125                        znode = zp;
1126                }
1127        }
1128
1129        /* Come back down, dirtying as we go */
1130        while (1) {
1131                struct ubifs_zbranch *zbr;
1132
1133                zp = znode->parent;
1134                if (zp) {
1135                        ubifs_assert(path[p - 1] >= 0);
1136                        ubifs_assert(path[p - 1] < zp->child_cnt);
1137                        zbr = &zp->zbranch[path[--p]];
1138                        znode = dirty_cow_znode(c, zbr);
1139                } else {
1140                        ubifs_assert(znode == c->zroot.znode);
1141                        znode = dirty_cow_znode(c, &c->zroot);
1142                }
1143                if (IS_ERR(znode) || !p)
1144                        break;
1145                ubifs_assert(path[p - 1] >= 0);
1146                ubifs_assert(path[p - 1] < znode->child_cnt);
1147                znode = znode->zbranch[path[p - 1]].znode;
1148        }
1149
1150        return znode;
1151}
1152
1153/**
1154 * ubifs_lookup_level0 - search for zero-level znode.
1155 * @c: UBIFS file-system description object
1156 * @key:  key to lookup
1157 * @zn: znode is returned here
1158 * @n: znode branch slot number is returned here
1159 *
1160 * This function looks up the TNC tree and search for zero-level znode which
1161 * refers key @key. The found zero-level znode is returned in @zn. There are 3
1162 * cases:
1163 *   o exact match, i.e. the found zero-level znode contains key @key, then %1
1164 *     is returned and slot number of the matched branch is stored in @n;
1165 *   o not exact match, which means that zero-level znode does not contain
1166 *     @key, then %0 is returned and slot number of the closest branch is stored
1167 *     in @n;
1168 *   o @key is so small that it is even less than the lowest key of the
1169 *     leftmost zero-level node, then %0 is returned and %0 is stored in @n.
1170 *
1171 * Note, when the TNC tree is traversed, some znodes may be absent, then this
1172 * function reads corresponding indexing nodes and inserts them to TNC. In
1173 * case of failure, a negative error code is returned.
1174 */
1175int ubifs_lookup_level0(struct ubifs_info *c, const union ubifs_key *key,
1176                        struct ubifs_znode **zn, int *n)
1177{
1178        int err, exact;
1179        struct ubifs_znode *znode;
1180        unsigned long time = get_seconds();
1181
1182        dbg_tnck(key, "search key ");
1183        ubifs_assert(key_type(c, key) < UBIFS_INVALID_KEY);
1184
1185        znode = c->zroot.znode;
1186        if (unlikely(!znode)) {
1187                znode = ubifs_load_znode(c, &c->zroot, NULL, 0);
1188                if (IS_ERR(znode))
1189                        return PTR_ERR(znode);
1190        }
1191
1192        znode->time = time;
1193
1194        while (1) {
1195                struct ubifs_zbranch *zbr;
1196
1197                exact = ubifs_search_zbranch(c, znode, key, n);
1198
1199                if (znode->level == 0)
1200                        break;
1201
1202                if (*n < 0)
1203                        *n = 0;
1204                zbr = &znode->zbranch[*n];
1205
1206                if (zbr->znode) {
1207                        znode->time = time;
1208                        znode = zbr->znode;
1209                        continue;
1210                }
1211
1212                /* znode is not in TNC cache, load it from the media */
1213                znode = ubifs_load_znode(c, zbr, znode, *n);
1214                if (IS_ERR(znode))
1215                        return PTR_ERR(znode);
1216        }
1217
1218        *zn = znode;
1219        if (exact || !is_hash_key(c, key) || *n != -1) {
1220                dbg_tnc("found %d, lvl %d, n %d", exact, znode->level, *n);
1221                return exact;
1222        }
1223
1224        /*
1225         * Here is a tricky place. We have not found the key and this is a
1226         * "hashed" key, which may collide. The rest of the code deals with
1227         * situations like this:
1228         *
1229         *                  | 3 | 5 |
1230         *                  /       \
1231         *          | 3 | 5 |      | 6 | 7 | (x)
1232         *
1233         * Or more a complex example:
1234         *
1235         *                | 1 | 5 |
1236         *                /       \
1237         *       | 1 | 3 |         | 5 | 8 |
1238         *              \           /
1239         *          | 5 | 5 |   | 6 | 7 | (x)
1240         *
1241         * In the examples, if we are looking for key "5", we may reach nodes
1242         * marked with "(x)". In this case what we have do is to look at the
1243         * left and see if there is "5" key there. If there is, we have to
1244         * return it.
1245         *
1246         * Note, this whole situation is possible because we allow to have
1247         * elements which are equivalent to the next key in the parent in the
1248         * children of current znode. For example, this happens if we split a
1249         * znode like this: | 3 | 5 | 5 | 6 | 7 |, which results in something
1250         * like this:
1251         *                      | 3 | 5 |
1252         *                       /     \
1253         *                | 3 | 5 |   | 5 | 6 | 7 |
1254         *                              ^
1255         * And this becomes what is at the first "picture" after key "5" marked
1256         * with "^" is removed. What could be done is we could prohibit
1257         * splitting in the middle of the colliding sequence. Also, when
1258         * removing the leftmost key, we would have to correct the key of the
1259         * parent node, which would introduce additional complications. Namely,
1260         * if we changed the leftmost key of the parent znode, the garbage
1261         * collector would be unable to find it (GC is doing this when GC'ing
1262         * indexing LEBs). Although we already have an additional RB-tree where
1263         * we save such changed znodes (see 'ins_clr_old_idx_znode()') until
1264         * after the commit. But anyway, this does not look easy to implement
1265         * so we did not try this.
1266         */
1267        err = tnc_prev(c, &znode, n);
1268        if (err == -ENOENT) {
1269                dbg_tnc("found 0, lvl %d, n -1", znode->level);
1270                *n = -1;
1271                return 0;
1272        }
1273        if (unlikely(err < 0))
1274                return err;
1275        if (keys_cmp(c, key, &znode->zbranch[*n].key)) {
1276                dbg_tnc("found 0, lvl %d, n -1", znode->level);
1277                *n = -1;
1278                return 0;
1279        }
1280
1281        dbg_tnc("found 1, lvl %d, n %d", znode->level, *n);
1282        *zn = znode;
1283        return 1;
1284}
1285
1286/**
1287 * lookup_level0_dirty - search for zero-level znode dirtying.
1288 * @c: UBIFS file-system description object
1289 * @key:  key to lookup
1290 * @zn: znode is returned here
1291 * @n: znode branch slot number is returned here
1292 *
1293 * This function looks up the TNC tree and search for zero-level znode which
1294 * refers key @key. The found zero-level znode is returned in @zn. There are 3
1295 * cases:
1296 *   o exact match, i.e. the found zero-level znode contains key @key, then %1
1297 *     is returned and slot number of the matched branch is stored in @n;
1298 *   o not exact match, which means that zero-level znode does not contain @key
1299 *     then %0 is returned and slot number of the closed branch is stored in
1300 *     @n;
1301 *   o @key is so small that it is even less than the lowest key of the
1302 *     leftmost zero-level node, then %0 is returned and %-1 is stored in @n.
1303 *
1304 * Additionally all znodes in the path from the root to the located zero-level
1305 * znode are marked as dirty.
1306 *
1307 * Note, when the TNC tree is traversed, some znodes may be absent, then this
1308 * function reads corresponding indexing nodes and inserts them to TNC. In
1309 * case of failure, a negative error code is returned.
1310 */
1311static int lookup_level0_dirty(struct ubifs_info *c, const union ubifs_key *key,
1312                               struct ubifs_znode **zn, int *n)
1313{
1314        int err, exact;
1315        struct ubifs_znode *znode;
1316        unsigned long time = get_seconds();
1317
1318        dbg_tnck(key, "search and dirty key ");
1319
1320        znode = c->zroot.znode;
1321        if (unlikely(!znode)) {
1322                znode = ubifs_load_znode(c, &c->zroot, NULL, 0);
1323                if (IS_ERR(znode))
1324                        return PTR_ERR(znode);
1325        }
1326
1327        znode = dirty_cow_znode(c, &c->zroot);
1328        if (IS_ERR(znode))
1329                return PTR_ERR(znode);
1330
1331        znode->time = time;
1332
1333        while (1) {
1334                struct ubifs_zbranch *zbr;
1335
1336                exact = ubifs_search_zbranch(c, znode, key, n);
1337
1338                if (znode->level == 0)
1339                        break;
1340
1341                if (*n < 0)
1342                        *n = 0;
1343                zbr = &znode->zbranch[*n];
1344
1345                if (zbr->znode) {
1346                        znode->time = time;
1347                        znode = dirty_cow_znode(c, zbr);
1348                        if (IS_ERR(znode))
1349                                return PTR_ERR(znode);
1350                        continue;
1351                }
1352
1353                /* znode is not in TNC cache, load it from the media */
1354                znode = ubifs_load_znode(c, zbr, znode, *n);
1355                if (IS_ERR(znode))
1356                        return PTR_ERR(znode);
1357                znode = dirty_cow_znode(c, zbr);
1358                if (IS_ERR(znode))
1359                        return PTR_ERR(znode);
1360        }
1361
1362        *zn = znode;
1363        if (exact || !is_hash_key(c, key) || *n != -1) {
1364                dbg_tnc("found %d, lvl %d, n %d", exact, znode->level, *n);
1365                return exact;
1366        }
1367
1368        /*
1369         * See huge comment at 'lookup_level0_dirty()' what is the rest of the
1370         * code.
1371         */
1372        err = tnc_prev(c, &znode, n);
1373        if (err == -ENOENT) {
1374                *n = -1;
1375                dbg_tnc("found 0, lvl %d, n -1", znode->level);
1376                return 0;
1377        }
1378        if (unlikely(err < 0))
1379                return err;
1380        if (keys_cmp(c, key, &znode->zbranch[*n].key)) {
1381                *n = -1;
1382                dbg_tnc("found 0, lvl %d, n -1", znode->level);
1383                return 0;
1384        }
1385
1386        if (znode->cnext || !ubifs_zn_dirty(znode)) {
1387                znode = dirty_cow_bottom_up(c, znode);
1388                if (IS_ERR(znode))
1389                        return PTR_ERR(znode);
1390        }
1391
1392        dbg_tnc("found 1, lvl %d, n %d", znode->level, *n);
1393        *zn = znode;
1394        return 1;
1395}
1396
1397/**
1398 * maybe_leb_gced - determine if a LEB may have been garbage collected.
1399 * @c: UBIFS file-system description object
1400 * @lnum: LEB number
1401 * @gc_seq1: garbage collection sequence number
1402 *
1403 * This function determines if @lnum may have been garbage collected since
1404 * sequence number @gc_seq1. If it may have been then %1 is returned, otherwise
1405 * %0 is returned.
1406 */
1407static int maybe_leb_gced(struct ubifs_info *c, int lnum, int gc_seq1)
1408{
1409        int gc_seq2, gced_lnum;
1410
1411        gced_lnum = c->gced_lnum;
1412        smp_rmb();
1413        gc_seq2 = c->gc_seq;
1414        /* Same seq means no GC */
1415        if (gc_seq1 == gc_seq2)
1416                return 0;
1417        /* Different by more than 1 means we don't know */
1418        if (gc_seq1 + 1 != gc_seq2)
1419                return 1;
1420        /*
1421         * We have seen the sequence number has increased by 1. Now we need to
1422         * be sure we read the right LEB number, so read it again.
1423         */
1424        smp_rmb();
1425        if (gced_lnum != c->gced_lnum)
1426                return 1;
1427        /* Finally we can check lnum */
1428        if (gced_lnum == lnum)
1429                return 1;
1430        return 0;
1431}
1432
1433/**
1434 * ubifs_tnc_locate - look up a file-system node and return it and its location.
1435 * @c: UBIFS file-system description object
1436 * @key: node key to lookup
1437 * @node: the node is returned here
1438 * @lnum: LEB number is returned here
1439 * @offs: offset is returned here
1440 *
1441 * This function looks up and reads node with key @key. The caller has to make
1442 * sure the @node buffer is large enough to fit the node. Returns zero in case
1443 * of success, %-ENOENT if the node was not found, and a negative error code in
1444 * case of failure. The node location can be returned in @lnum and @offs.
1445 */
1446int ubifs_tnc_locate(struct ubifs_info *c, const union ubifs_key *key,
1447                     void *node, int *lnum, int *offs)
1448{
1449        int found, n, err, safely = 0, gc_seq1;
1450        struct ubifs_znode *znode;
1451        struct ubifs_zbranch zbr, *zt;
1452
1453again:
1454        mutex_lock(&c->tnc_mutex);
1455        found = ubifs_lookup_level0(c, key, &znode, &n);
1456        if (!found) {
1457                err = -ENOENT;
1458                goto out;
1459        } else if (found < 0) {
1460                err = found;
1461                goto out;
1462        }
1463        zt = &znode->zbranch[n];
1464        if (lnum) {
1465                *lnum = zt->lnum;
1466                *offs = zt->offs;
1467        }
1468        if (is_hash_key(c, key)) {
1469                /*
1470                 * In this case the leaf node cache gets used, so we pass the
1471                 * address of the zbranch and keep the mutex locked
1472                 */
1473                err = tnc_read_node_nm(c, zt, node);
1474                goto out;
1475        }
1476        if (safely) {
1477                err = ubifs_tnc_read_node(c, zt, node);
1478                goto out;
1479        }
1480        /* Drop the TNC mutex prematurely and race with garbage collection */
1481        zbr = znode->zbranch[n];
1482        gc_seq1 = c->gc_seq;
1483        mutex_unlock(&c->tnc_mutex);
1484
1485        if (ubifs_get_wbuf(c, zbr.lnum)) {
1486                /* We do not GC journal heads */
1487                err = ubifs_tnc_read_node(c, &zbr, node);
1488                return err;
1489        }
1490
1491        err = fallible_read_node(c, key, &zbr, node);
1492        if (err <= 0 || maybe_leb_gced(c, zbr.lnum, gc_seq1)) {
1493                /*
1494                 * The node may have been GC'ed out from under us so try again
1495                 * while keeping the TNC mutex locked.
1496                 */
1497                safely = 1;
1498                goto again;
1499        }
1500        return 0;
1501
1502out:
1503        mutex_unlock(&c->tnc_mutex);
1504        return err;
1505}
1506
1507/**
1508 * ubifs_tnc_get_bu_keys - lookup keys for bulk-read.
1509 * @c: UBIFS file-system description object
1510 * @bu: bulk-read parameters and results
1511 *
1512 * Lookup consecutive data node keys for the same inode that reside
1513 * consecutively in the same LEB. This function returns zero in case of success
1514 * and a negative error code in case of failure.
1515 *
1516 * Note, if the bulk-read buffer length (@bu->buf_len) is known, this function
1517 * makes sure bulk-read nodes fit the buffer. Otherwise, this function prepares
1518 * maximum possible amount of nodes for bulk-read.
1519 */
1520int ubifs_tnc_get_bu_keys(struct ubifs_info *c, struct bu_info *bu)
1521{
1522        int n, err = 0, lnum = -1, uninitialized_var(offs);
1523        int uninitialized_var(len);
1524        unsigned int block = key_block(c, &bu->key);
1525        struct ubifs_znode *znode;
1526
1527        bu->cnt = 0;
1528        bu->blk_cnt = 0;
1529        bu->eof = 0;
1530
1531        mutex_lock(&c->tnc_mutex);
1532        /* Find first key */
1533        err = ubifs_lookup_level0(c, &bu->key, &znode, &n);
1534        if (err < 0)
1535                goto out;
1536        if (err) {
1537                /* Key found */
1538                len = znode->zbranch[n].len;
1539                /* The buffer must be big enough for at least 1 node */
1540                if (len > bu->buf_len) {
1541                        err = -EINVAL;
1542                        goto out;
1543                }
1544                /* Add this key */
1545                bu->zbranch[bu->cnt++] = znode->zbranch[n];
1546                bu->blk_cnt += 1;
1547                lnum = znode->zbranch[n].lnum;
1548                offs = ALIGN(znode->zbranch[n].offs + len, 8);
1549        }
1550        while (1) {
1551                struct ubifs_zbranch *zbr;
1552                union ubifs_key *key;
1553                unsigned int next_block;
1554
1555                /* Find next key */
1556                err = tnc_next(c, &znode, &n);
1557                if (err)
1558                        goto out;
1559                zbr = &znode->zbranch[n];
1560                key = &zbr->key;
1561                /* See if there is another data key for this file */
1562                if (key_inum(c, key) != key_inum(c, &bu->key) ||
1563                    key_type(c, key) != UBIFS_DATA_KEY) {
1564                        err = -ENOENT;
1565                        goto out;
1566                }
1567                if (lnum < 0) {
1568                        /* First key found */
1569                        lnum = zbr->lnum;
1570                        offs = ALIGN(zbr->offs + zbr->len, 8);
1571                        len = zbr->len;
1572                        if (len > bu->buf_len) {
1573                                err = -EINVAL;
1574                                goto out;
1575                        }
1576                } else {
1577                        /*
1578                         * The data nodes must be in consecutive positions in
1579                         * the same LEB.
1580                         */
1581                        if (zbr->lnum != lnum || zbr->offs != offs)
1582                                goto out;
1583                        offs += ALIGN(zbr->len, 8);
1584                        len = ALIGN(len, 8) + zbr->len;
1585                        /* Must not exceed buffer length */
1586                        if (len > bu->buf_len)
1587                                goto out;
1588                }
1589                /* Allow for holes */
1590                next_block = key_block(c, key);
1591                bu->blk_cnt += (next_block - block - 1);
1592                if (bu->blk_cnt >= UBIFS_MAX_BULK_READ)
1593                        goto out;
1594                block = next_block;
1595                /* Add this key */
1596                bu->zbranch[bu->cnt++] = *zbr;
1597                bu->blk_cnt += 1;
1598                /* See if we have room for more */
1599                if (bu->cnt >= UBIFS_MAX_BULK_READ)
1600                        goto out;
1601                if (bu->blk_cnt >= UBIFS_MAX_BULK_READ)
1602                        goto out;
1603        }
1604out:
1605        if (err == -ENOENT) {
1606                bu->eof = 1;
1607                err = 0;
1608        }
1609        bu->gc_seq = c->gc_seq;
1610        mutex_unlock(&c->tnc_mutex);
1611        if (err)
1612                return err;
1613        /*
1614         * An enormous hole could cause bulk-read to encompass too many
1615         * page cache pages, so limit the number here.
1616         */
1617        if (bu->blk_cnt > UBIFS_MAX_BULK_READ)
1618                bu->blk_cnt = UBIFS_MAX_BULK_READ;
1619        /*
1620         * Ensure that bulk-read covers a whole number of page cache
1621         * pages.
1622         */
1623        if (UBIFS_BLOCKS_PER_PAGE == 1 ||
1624            !(bu->blk_cnt & (UBIFS_BLOCKS_PER_PAGE - 1)))
1625                return 0;
1626        if (bu->eof) {
1627                /* At the end of file we can round up */
1628                bu->blk_cnt += UBIFS_BLOCKS_PER_PAGE - 1;
1629                return 0;
1630        }
1631        /* Exclude data nodes that do not make up a whole page cache page */
1632        block = key_block(c, &bu->key) + bu->blk_cnt;
1633        block &= ~(UBIFS_BLOCKS_PER_PAGE - 1);
1634        while (bu->cnt) {
1635                if (key_block(c, &bu->zbranch[bu->cnt - 1].key) < block)
1636                        break;
1637                bu->cnt -= 1;
1638        }
1639        return 0;
1640}
1641
1642/**
1643 * read_wbuf - bulk-read from a LEB with a wbuf.
1644 * @wbuf: wbuf that may overlap the read
1645 * @buf: buffer into which to read
1646 * @len: read length
1647 * @lnum: LEB number from which to read
1648 * @offs: offset from which to read
1649 *
1650 * This functions returns %0 on success or a negative error code on failure.
1651 */
1652static int read_wbuf(struct ubifs_wbuf *wbuf, void *buf, int len, int lnum,
1653                     int offs)
1654{
1655        const struct ubifs_info *c = wbuf->c;
1656        int rlen, overlap;
1657
1658        dbg_io("LEB %d:%d, length %d", lnum, offs, len);
1659        ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
1660        ubifs_assert(!(offs & 7) && offs < c->leb_size);
1661        ubifs_assert(offs + len <= c->leb_size);
1662
1663        spin_lock(&wbuf->lock);
1664        overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
1665        if (!overlap) {
1666                /* We may safely unlock the write-buffer and read the data */
1667                spin_unlock(&wbuf->lock);
1668                return ubifs_leb_read(c, lnum, buf, offs, len, 0);
1669        }
1670
1671        /* Don't read under wbuf */
1672        rlen = wbuf->offs - offs;
1673        if (rlen < 0)
1674                rlen = 0;
1675
1676        /* Copy the rest from the write-buffer */
1677        memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
1678        spin_unlock(&wbuf->lock);
1679
1680        if (rlen > 0)
1681                /* Read everything that goes before write-buffer */
1682                return ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
1683
1684        return 0;
1685}
1686
1687/**
1688 * validate_data_node - validate data nodes for bulk-read.
1689 * @c: UBIFS file-system description object
1690 * @buf: buffer containing data node to validate
1691 * @zbr: zbranch of data node to validate
1692 *
1693 * This functions returns %0 on success or a negative error code on failure.
1694 */
1695static int validate_data_node(struct ubifs_info *c, void *buf,
1696                              struct ubifs_zbranch *zbr)
1697{
1698        union ubifs_key key1;
1699        struct ubifs_ch *ch = buf;
1700        int err, len;
1701
1702        if (ch->node_type != UBIFS_DATA_NODE) {
1703                ubifs_err("bad node type (%d but expected %d)",
1704                          ch->node_type, UBIFS_DATA_NODE);
1705                goto out_err;
1706        }
1707
1708        err = ubifs_check_node(c, buf, zbr->lnum, zbr->offs, 0, 0);
1709        if (err) {
1710                ubifs_err("expected node type %d", UBIFS_DATA_NODE);
1711                goto out;
1712        }
1713
1714        len = le32_to_cpu(ch->len);
1715        if (len != zbr->len) {
1716                ubifs_err("bad node length %d, expected %d", len, zbr->len);
1717                goto out_err;
1718        }
1719
1720        /* Make sure the key of the read node is correct */
1721        key_read(c, buf + UBIFS_KEY_OFFSET, &key1);
1722        if (!keys_eq(c, &zbr->key, &key1)) {
1723                ubifs_err("bad key in node at LEB %d:%d",
1724                          zbr->lnum, zbr->offs);
1725                dbg_tnck(&zbr->key, "looked for key ");
1726                dbg_tnck(&key1, "found node's key ");
1727                goto out_err;
1728        }
1729
1730        return 0;
1731
1732out_err:
1733        err = -EINVAL;
1734out:
1735        ubifs_err("bad node at LEB %d:%d", zbr->lnum, zbr->offs);
1736        ubifs_dump_node(c, buf);
1737        dump_stack();
1738        return err;
1739}
1740
1741/**
1742 * ubifs_tnc_bulk_read - read a number of data nodes in one go.
1743 * @c: UBIFS file-system description object
1744 * @bu: bulk-read parameters and results
1745 *
1746 * This functions reads and validates the data nodes that were identified by the
1747 * 'ubifs_tnc_get_bu_keys()' function. This functions returns %0 on success,
1748 * -EAGAIN to indicate a race with GC, or another negative error code on
1749 * failure.
1750 */
1751int ubifs_tnc_bulk_read(struct ubifs_info *c, struct bu_info *bu)
1752{
1753        int lnum = bu->zbranch[0].lnum, offs = bu->zbranch[0].offs, len, err, i;
1754        struct ubifs_wbuf *wbuf;
1755        void *buf;
1756
1757        len = bu->zbranch[bu->cnt - 1].offs;
1758        len += bu->zbranch[bu->cnt - 1].len - offs;
1759        if (len > bu->buf_len) {
1760                ubifs_err("buffer too small %d vs %d", bu->buf_len, len);
1761                return -EINVAL;
1762        }
1763
1764        /* Do the read */
1765        wbuf = ubifs_get_wbuf(c, lnum);
1766        if (wbuf)
1767                err = read_wbuf(wbuf, bu->buf, len, lnum, offs);
1768        else
1769                err = ubifs_leb_read(c, lnum, bu->buf, offs, len, 0);
1770
1771        /* Check for a race with GC */
1772        if (maybe_leb_gced(c, lnum, bu->gc_seq))
1773                return -EAGAIN;
1774
1775        if (err && err != -EBADMSG) {
1776                ubifs_err("failed to read from LEB %d:%d, error %d",
1777                          lnum, offs, err);
1778                dump_stack();
1779                dbg_tnck(&bu->key, "key ");
1780                return err;
1781        }
1782
1783        /* Validate the nodes read */
1784        buf = bu->buf;
1785        for (i = 0; i < bu->cnt; i++) {
1786                err = validate_data_node(c, buf, &bu->zbranch[i]);
1787                if (err)
1788                        return err;
1789                buf = buf + ALIGN(bu->zbranch[i].len, 8);
1790        }
1791
1792        return 0;
1793}
1794
1795/**
1796 * do_lookup_nm- look up a "hashed" node.
1797 * @c: UBIFS file-system description object
1798 * @key: node key to lookup
1799 * @node: the node is returned here
1800 * @nm: node name
1801 *
1802 * This function look up and reads a node which contains name hash in the key.
1803 * Since the hash may have collisions, there may be many nodes with the same
1804 * key, so we have to sequentially look to all of them until the needed one is
1805 * found. This function returns zero in case of success, %-ENOENT if the node
1806 * was not found, and a negative error code in case of failure.
1807 */
1808static int do_lookup_nm(struct ubifs_info *c, const union ubifs_key *key,
1809                        void *node, const struct qstr *nm)
1810{
1811        int found, n, err;
1812        struct ubifs_znode *znode;
1813
1814        dbg_tnck(key, "name '%.*s' key ", nm->len, nm->name);
1815        mutex_lock(&c->tnc_mutex);
1816        found = ubifs_lookup_level0(c, key, &znode, &n);
1817        if (!found) {
1818                err = -ENOENT;
1819                goto out_unlock;
1820        } else if (found < 0) {
1821                err = found;
1822                goto out_unlock;
1823        }
1824
1825        ubifs_assert(n >= 0);
1826
1827        err = resolve_collision(c, key, &znode, &n, nm);
1828        dbg_tnc("rc returned %d, znode %p, n %d", err, znode, n);
1829        if (unlikely(err < 0))
1830                goto out_unlock;
1831        if (err == 0) {
1832                err = -ENOENT;
1833                goto out_unlock;
1834        }
1835
1836        err = tnc_read_node_nm(c, &znode->zbranch[n], node);
1837
1838out_unlock:
1839        mutex_unlock(&c->tnc_mutex);
1840        return err;
1841}
1842
1843/**
1844 * ubifs_tnc_lookup_nm - look up a "hashed" node.
1845 * @c: UBIFS file-system description object
1846 * @key: node key to lookup
1847 * @node: the node is returned here
1848 * @nm: node name
1849 *
1850 * This function look up and reads a node which contains name hash in the key.
1851 * Since the hash may have collisions, there may be many nodes with the same
1852 * key, so we have to sequentially look to all of them until the needed one is
1853 * found. This function returns zero in case of success, %-ENOENT if the node
1854 * was not found, and a negative error code in case of failure.
1855 */
1856int ubifs_tnc_lookup_nm(struct ubifs_info *c, const union ubifs_key *key,
1857                        void *node, const struct qstr *nm)
1858{
1859        int err, len;
1860        const struct ubifs_dent_node *dent = node;
1861
1862        /*
1863         * We assume that in most of the cases there are no name collisions and
1864         * 'ubifs_tnc_lookup()' returns us the right direntry.
1865         */
1866        err = ubifs_tnc_lookup(c, key, node);
1867        if (err)
1868                return err;
1869
1870        len = le16_to_cpu(dent->nlen);
1871        if (nm->len == len && !memcmp(dent->name, nm->name, len))
1872                return 0;
1873
1874        /*
1875         * Unluckily, there are hash collisions and we have to iterate over
1876         * them look at each direntry with colliding name hash sequentially.
1877         */
1878        return do_lookup_nm(c, key, node, nm);
1879}
1880
1881/**
1882 * correct_parent_keys - correct parent znodes' keys.
1883 * @c: UBIFS file-system description object
1884 * @znode: znode to correct parent znodes for
1885 *
1886 * This is a helper function for 'tnc_insert()'. When the key of the leftmost
1887 * zbranch changes, keys of parent znodes have to be corrected. This helper
1888 * function is called in such situations and corrects the keys if needed.
1889 */
1890static void correct_parent_keys(const struct ubifs_info *c,
1891                                struct ubifs_znode *znode)
1892{
1893        union ubifs_key *key, *key1;
1894
1895        ubifs_assert(znode->parent);
1896        ubifs_assert(znode->iip == 0);
1897
1898        key = &znode->zbranch[0].key;
1899        key1 = &znode->parent->zbranch[0].key;
1900
1901        while (keys_cmp(c, key, key1) < 0) {
1902                key_copy(c, key, key1);
1903                znode = znode->parent;
1904                znode->alt = 1;
1905                if (!znode->parent || znode->iip)
1906                        break;
1907                key1 = &znode->parent->zbranch[0].key;
1908        }
1909}
1910
1911/**
1912 * insert_zbranch - insert a zbranch into a znode.
1913 * @znode: znode into which to insert
1914 * @zbr: zbranch to insert
1915 * @n: slot number to insert to
1916 *
1917 * This is a helper function for 'tnc_insert()'. UBIFS does not allow "gaps" in
1918 * znode's array of zbranches and keeps zbranches consolidated, so when a new
1919 * zbranch has to be inserted to the @znode->zbranches[]' array at the @n-th
1920 * slot, zbranches starting from @n have to be moved right.
1921 */
1922static void insert_zbranch(struct ubifs_znode *znode,
1923                           const struct ubifs_zbranch *zbr, int n)
1924{
1925        int i;
1926
1927        ubifs_assert(ubifs_zn_dirty(znode));
1928
1929        if (znode->level) {
1930                for (i = znode->child_cnt; i > n; i--) {
1931                        znode->zbranch[i] = znode->zbranch[i - 1];
1932                        if (znode->zbranch[i].znode)
1933                                znode->zbranch[i].znode->iip = i;
1934                }
1935                if (zbr->znode)
1936                        zbr->znode->iip = n;
1937        } else
1938                for (i = znode->child_cnt; i > n; i--)
1939                        znode->zbranch[i] = znode->zbranch[i - 1];
1940
1941        znode->zbranch[n] = *zbr;
1942        znode->child_cnt += 1;
1943
1944        /*
1945         * After inserting at slot zero, the lower bound of the key range of
1946         * this znode may have changed. If this znode is subsequently split
1947         * then the upper bound of the key range may change, and furthermore
1948         * it could change to be lower than the original lower bound. If that
1949         * happens, then it will no longer be possible to find this znode in the
1950         * TNC using the key from the index node on flash. That is bad because
1951         * if it is not found, we will assume it is obsolete and may overwrite
1952         * it. Then if there is an unclean unmount, we will start using the
1953         * old index which will be broken.
1954         *
1955         * So we first mark znodes that have insertions at slot zero, and then
1956         * if they are split we add their lnum/offs to the old_idx tree.
1957         */
1958        if (n == 0)
1959                znode->alt = 1;
1960}
1961
1962/**
1963 * tnc_insert - insert a node into TNC.
1964 * @c: UBIFS file-system description object
1965 * @znode: znode to insert into
1966 * @zbr: branch to insert
1967 * @n: slot number to insert new zbranch to
1968 *
1969 * This function inserts a new node described by @zbr into znode @znode. If
1970 * znode does not have a free slot for new zbranch, it is split. Parent znodes
1971 * are splat as well if needed. Returns zero in case of success or a negative
1972 * error code in case of failure.
1973 */
1974static int tnc_insert(struct ubifs_info *c, struct ubifs_znode *znode,
1975                      struct ubifs_zbranch *zbr, int n)
1976{
1977        struct ubifs_znode *zn, *zi, *zp;
1978        int i, keep, move, appending = 0;
1979        union ubifs_key *key = &zbr->key, *key1;
1980
1981        ubifs_assert(n >= 0 && n <= c->fanout);
1982
1983        /* Implement naive insert for now */
1984again:
1985        zp = znode->parent;
1986        if (znode->child_cnt < c->fanout) {
1987                ubifs_assert(n != c->fanout);
1988                dbg_tnck(key, "inserted at %d level %d, key ", n, znode->level);
1989
1990                insert_zbranch(znode, zbr, n);
1991
1992                /* Ensure parent's key is correct */
1993                if (n == 0 && zp && znode->iip == 0)
1994                        correct_parent_keys(c, znode);
1995
1996                return 0;
1997        }
1998
1999        /*
2000         * Unfortunately, @znode does not have more empty slots and we have to
2001         * split it.
2002         */
2003        dbg_tnck(key, "splitting level %d, key ", znode->level);
2004
2005        if (znode->alt)
2006                /*
2007                 * We can no longer be sure of finding this znode by key, so we
2008                 * record it in the old_idx tree.
2009                 */
2010                ins_clr_old_idx_znode(c, znode);
2011
2012        zn = kzalloc(c->max_znode_sz, GFP_NOFS);
2013        if (!zn)
2014                return -ENOMEM;
2015        zn->parent = zp;
2016        zn->level = znode->level;
2017
2018        /* Decide where to split */
2019        if (znode->level == 0 && key_type(c, key) == UBIFS_DATA_KEY) {
2020                /* Try not to split consecutive data keys */
2021                if (n == c->fanout) {
2022                        key1 = &znode->zbranch[n - 1].key;
2023                        if (key_inum(c, key1) == key_inum(c, key) &&
2024                            key_type(c, key1) == UBIFS_DATA_KEY)
2025                                appending = 1;
2026                } else
2027                        goto check_split;
2028        } else if (appending && n != c->fanout) {
2029                /* Try not to split consecutive data keys */
2030                appending = 0;
2031check_split:
2032                if (n >= (c->fanout + 1) / 2) {
2033                        key1 = &znode->zbranch[0].key;
2034                        if (key_inum(c, key1) == key_inum(c, key) &&
2035                            key_type(c, key1) == UBIFS_DATA_KEY) {
2036                                key1 = &znode->zbranch[n].key;
2037                                if (key_inum(c, key1) != key_inum(c, key) ||
2038                                    key_type(c, key1) != UBIFS_DATA_KEY) {
2039                                        keep = n;
2040                                        move = c->fanout - keep;
2041                                        zi = znode;
2042                                        goto do_split;
2043                                }
2044                        }
2045                }
2046        }
2047
2048        if (appending) {
2049                keep = c->fanout;
2050                move = 0;
2051        } else {
2052                keep = (c->fanout + 1) / 2;
2053                move = c->fanout - keep;
2054        }
2055
2056        /*
2057         * Although we don't at present, we could look at the neighbors and see
2058         * if we can move some zbranches there.
2059         */
2060
2061        if (n < keep) {
2062                /* Insert into existing znode */
2063                zi = znode;
2064                move += 1;
2065                keep -= 1;
2066        } else {
2067                /* Insert into new znode */
2068                zi = zn;
2069                n -= keep;
2070                /* Re-parent */
2071                if (zn->level != 0)
2072                        zbr->znode->parent = zn;
2073        }
2074
2075do_split:
2076
2077        __set_bit(DIRTY_ZNODE, &zn->flags);
2078        atomic_long_inc(&c->dirty_zn_cnt);
2079
2080        zn->child_cnt = move;
2081        znode->child_cnt = keep;
2082
2083        dbg_tnc("moving %d, keeping %d", move, keep);
2084
2085        /* Move zbranch */
2086        for (i = 0; i < move; i++) {
2087                zn->zbranch[i] = znode->zbranch[keep + i];
2088                /* Re-parent */
2089                if (zn->level != 0)
2090                        if (zn->zbranch[i].znode) {
2091                                zn->zbranch[i].znode->parent = zn;
2092                                zn->zbranch[i].znode->iip = i;
2093                        }
2094        }
2095
2096        /* Insert new key and branch */
2097        dbg_tnck(key, "inserting at %d level %d, key ", n, zn->level);
2098
2099        insert_zbranch(zi, zbr, n);
2100
2101        /* Insert new znode (produced by spitting) into the parent */
2102        if (zp) {
2103                if (n == 0 && zi == znode && znode->iip == 0)
2104                        correct_parent_keys(c, znode);
2105
2106                /* Locate insertion point */
2107                n = znode->iip + 1;
2108
2109                /* Tail recursion */
2110                zbr->key = zn->zbranch[0].key;
2111                zbr->znode = zn;
2112                zbr->lnum = 0;
2113                zbr->offs = 0;
2114                zbr->len = 0;
2115                znode = zp;
2116
2117                goto again;
2118        }
2119
2120        /* We have to split root znode */
2121        dbg_tnc("creating new zroot at level %d", znode->level + 1);
2122
2123        zi = kzalloc(c->max_znode_sz, GFP_NOFS);
2124        if (!zi)
2125                return -ENOMEM;
2126
2127        zi->child_cnt = 2;
2128        zi->level = znode->level + 1;
2129
2130        __set_bit(DIRTY_ZNODE, &zi->flags);
2131        atomic_long_inc(&c->dirty_zn_cnt);
2132
2133        zi->zbranch[0].key = znode->zbranch[0].key;
2134        zi->zbranch[0].znode = znode;
2135        zi->zbranch[0].lnum = c->zroot.lnum;
2136        zi->zbranch[0].offs = c->zroot.offs;
2137        zi->zbranch[0].len = c->zroot.len;
2138        zi->zbranch[1].key = zn->zbranch[0].key;
2139        zi->zbranch[1].znode = zn;
2140
2141        c->zroot.lnum = 0;
2142        c->zroot.offs = 0;
2143        c->zroot.len = 0;
2144        c->zroot.znode = zi;
2145
2146        zn->parent = zi;
2147        zn->iip = 1;
2148        znode->parent = zi;
2149        znode->iip = 0;
2150
2151        return 0;
2152}
2153
2154/**
2155 * ubifs_tnc_add - add a node to TNC.
2156 * @c: UBIFS file-system description object
2157 * @key: key to add
2158 * @lnum: LEB number of node
2159 * @offs: node offset
2160 * @len: node length
2161 *
2162 * This function adds a node with key @key to TNC. The node may be new or it may
2163 * obsolete some existing one. Returns %0 on success or negative error code on
2164 * failure.
2165 */
2166int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
2167                  int offs, int len)
2168{
2169        int found, n, err = 0;
2170        struct ubifs_znode *znode;
2171
2172        mutex_lock(&c->tnc_mutex);
2173        dbg_tnck(key, "%d:%d, len %d, key ", lnum, offs, len);
2174        found = lookup_level0_dirty(c, key, &znode, &n);
2175        if (!found) {
2176                struct ubifs_zbranch zbr;
2177
2178                zbr.znode = NULL;
2179                zbr.lnum = lnum;
2180                zbr.offs = offs;
2181                zbr.len = len;
2182                key_copy(c, key, &zbr.key);
2183                err = tnc_insert(c, znode, &zbr, n + 1);
2184        } else if (found == 1) {
2185                struct ubifs_zbranch *zbr = &znode->zbranch[n];
2186
2187                lnc_free(zbr);
2188                err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2189                zbr->lnum = lnum;
2190                zbr->offs = offs;
2191                zbr->len = len;
2192        } else
2193                err = found;
2194        if (!err)
2195                err = dbg_check_tnc(c, 0);
2196        mutex_unlock(&c->tnc_mutex);
2197
2198        return err;
2199}
2200
2201/**
2202 * ubifs_tnc_replace - replace a node in the TNC only if the old node is found.
2203 * @c: UBIFS file-system description object
2204 * @key: key to add
2205 * @old_lnum: LEB number of old node
2206 * @old_offs: old node offset
2207 * @lnum: LEB number of node
2208 * @offs: node offset
2209 * @len: node length
2210 *
2211 * This function replaces a node with key @key in the TNC only if the old node
2212 * is found.  This function is called by garbage collection when node are moved.
2213 * Returns %0 on success or negative error code on failure.
2214 */
2215int ubifs_tnc_replace(struct ubifs_info *c, const union ubifs_key *key,
2216                      int old_lnum, int old_offs, int lnum, int offs, int len)
2217{
2218        int found, n, err = 0;
2219        struct ubifs_znode *znode;
2220
2221        mutex_lock(&c->tnc_mutex);
2222        dbg_tnck(key, "old LEB %d:%d, new LEB %d:%d, len %d, key ", old_lnum,
2223                 old_offs, lnum, offs, len);
2224        found = lookup_level0_dirty(c, key, &znode, &n);
2225        if (found < 0) {
2226                err = found;
2227                goto out_unlock;
2228        }
2229
2230        if (found == 1) {
2231                struct ubifs_zbranch *zbr = &znode->zbranch[n];
2232
2233                found = 0;
2234                if (zbr->lnum == old_lnum && zbr->offs == old_offs) {
2235                        lnc_free(zbr);
2236                        err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2237                        if (err)
2238                                goto out_unlock;
2239                        zbr->lnum = lnum;
2240                        zbr->offs = offs;
2241                        zbr->len = len;
2242                        found = 1;
2243                } else if (is_hash_key(c, key)) {
2244                        found = resolve_collision_directly(c, key, &znode, &n,
2245                                                           old_lnum, old_offs);
2246                        dbg_tnc("rc returned %d, znode %p, n %d, LEB %d:%d",
2247                                found, znode, n, old_lnum, old_offs);
2248                        if (found < 0) {
2249                                err = found;
2250                                goto out_unlock;
2251                        }
2252
2253                        if (found) {
2254                                /* Ensure the znode is dirtied */
2255                                if (znode->cnext || !ubifs_zn_dirty(znode)) {
2256                                        znode = dirty_cow_bottom_up(c, znode);
2257                                        if (IS_ERR(znode)) {
2258                                                err = PTR_ERR(znode);
2259                                                goto out_unlock;
2260                                        }
2261                                }
2262                                zbr = &znode->zbranch[n];
2263                                lnc_free(zbr);
2264                                err = ubifs_add_dirt(c, zbr->lnum,
2265                                                     zbr->len);
2266                                if (err)
2267                                        goto out_unlock;
2268                                zbr->lnum = lnum;
2269                                zbr->offs = offs;
2270                                zbr->len = len;
2271                        }
2272                }
2273        }
2274
2275        if (!found)
2276                err = ubifs_add_dirt(c, lnum, len);
2277
2278        if (!err)
2279                err = dbg_check_tnc(c, 0);
2280
2281out_unlock:
2282        mutex_unlock(&c->tnc_mutex);
2283        return err;
2284}
2285
2286/**
2287 * ubifs_tnc_add_nm - add a "hashed" node to TNC.
2288 * @c: UBIFS file-system description object
2289 * @key: key to add
2290 * @lnum: LEB number of node
2291 * @offs: node offset
2292 * @len: node length
2293 * @nm: node name
2294 *
2295 * This is the same as 'ubifs_tnc_add()' but it should be used with keys which
2296 * may have collisions, like directory entry keys.
2297 */
2298int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
2299                     int lnum, int offs, int len, const struct qstr *nm)
2300{
2301        int found, n, err = 0;
2302        struct ubifs_znode *znode;
2303
2304        mutex_lock(&c->tnc_mutex);
2305        dbg_tnck(key, "LEB %d:%d, name '%.*s', key ",
2306                 lnum, offs, nm->len, nm->name);
2307        found = lookup_level0_dirty(c, key, &znode, &n);
2308        if (found < 0) {
2309                err = found;
2310                goto out_unlock;
2311        }
2312
2313        if (found == 1) {
2314                if (c->replaying)
2315                        found = fallible_resolve_collision(c, key, &znode, &n,
2316                                                           nm, 1);
2317                else
2318                        found = resolve_collision(c, key, &znode, &n, nm);
2319                dbg_tnc("rc returned %d, znode %p, n %d", found, znode, n);
2320                if (found < 0) {
2321                        err = found;
2322                        goto out_unlock;
2323                }
2324
2325                /* Ensure the znode is dirtied */
2326                if (znode->cnext || !ubifs_zn_dirty(znode)) {
2327                        znode = dirty_cow_bottom_up(c, znode);
2328                        if (IS_ERR(znode)) {
2329                                err = PTR_ERR(znode);
2330                                goto out_unlock;
2331                        }
2332                }
2333
2334                if (found == 1) {
2335                        struct ubifs_zbranch *zbr = &znode->zbranch[n];
2336
2337                        lnc_free(zbr);
2338                        err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2339                        zbr->lnum = lnum;
2340                        zbr->offs = offs;
2341                        zbr->len = len;
2342                        goto out_unlock;
2343                }
2344        }
2345
2346        if (!found) {
2347                struct ubifs_zbranch zbr;
2348
2349                zbr.znode = NULL;
2350                zbr.lnum = lnum;
2351                zbr.offs = offs;
2352                zbr.len = len;
2353                key_copy(c, key, &zbr.key);
2354                err = tnc_insert(c, znode, &zbr, n + 1);
2355                if (err)
2356                        goto out_unlock;
2357                if (c->replaying) {
2358                        /*
2359                         * We did not find it in the index so there may be a
2360                         * dangling branch still in the index. So we remove it
2361                         * by passing 'ubifs_tnc_remove_nm()' the same key but
2362                         * an unmatchable name.
2363                         */
2364                        struct qstr noname = { .name = "" };
2365
2366                        err = dbg_check_tnc(c, 0);
2367                        mutex_unlock(&c->tnc_mutex);
2368                        if (err)
2369                                return err;
2370                        return ubifs_tnc_remove_nm(c, key, &noname);
2371                }
2372        }
2373
2374out_unlock:
2375        if (!err)
2376                err = dbg_check_tnc(c, 0);
2377        mutex_unlock(&c->tnc_mutex);
2378        return err;
2379}
2380
2381/**
2382 * tnc_delete - delete a znode form TNC.
2383 * @c: UBIFS file-system description object
2384 * @znode: znode to delete from
2385 * @n: zbranch slot number to delete
2386 *
2387 * This function deletes a leaf node from @n-th slot of @znode. Returns zero in
2388 * case of success and a negative error code in case of failure.
2389 */
2390static int tnc_delete(struct ubifs_info *c, struct ubifs_znode *znode, int n)
2391{
2392        struct ubifs_zbranch *zbr;
2393        struct ubifs_znode *zp;
2394        int i, err;
2395
2396        /* Delete without merge for now */
2397        ubifs_assert(znode->level == 0);
2398        ubifs_assert(n >= 0 && n < c->fanout);
2399        dbg_tnck(&znode->zbranch[n].key, "deleting key ");
2400
2401        zbr = &znode->zbranch[n];
2402        lnc_free(zbr);
2403
2404        err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2405        if (err) {
2406                ubifs_dump_znode(c, znode);
2407                return err;
2408        }
2409
2410        /* We do not "gap" zbranch slots */
2411        for (i = n; i < znode->child_cnt - 1; i++)
2412                znode->zbranch[i] = znode->zbranch[i + 1];
2413        znode->child_cnt -= 1;
2414
2415        if (znode->child_cnt > 0)
2416                return 0;
2417
2418        /*
2419         * This was the last zbranch, we have to delete this znode from the
2420         * parent.
2421         */
2422
2423        do {
2424                ubifs_assert(!ubifs_zn_obsolete(znode));
2425                ubifs_assert(ubifs_zn_dirty(znode));
2426
2427                zp = znode->parent;
2428                n = znode->iip;
2429
2430                atomic_long_dec(&c->dirty_zn_cnt);
2431
2432                err = insert_old_idx_znode(c, znode);
2433                if (err)
2434                        return err;
2435
2436                if (znode->cnext) {
2437                        __set_bit(OBSOLETE_ZNODE, &znode->flags);
2438                        atomic_long_inc(&c->clean_zn_cnt);
2439                        atomic_long_inc(&ubifs_clean_zn_cnt);
2440                } else
2441                        kfree(znode);
2442                znode = zp;
2443        } while (znode->child_cnt == 1); /* while removing last child */
2444
2445        /* Remove from znode, entry n - 1 */
2446        znode->child_cnt -= 1;
2447        ubifs_assert(znode->level != 0);
2448        for (i = n; i < znode->child_cnt; i++) {
2449                znode->zbranch[i] = znode->zbranch[i + 1];
2450                if (znode->zbranch[i].znode)
2451                        znode->zbranch[i].znode->iip = i;
2452        }
2453
2454        /*
2455         * If this is the root and it has only 1 child then
2456         * collapse the tree.
2457         */
2458        if (!znode->parent) {
2459                while (znode->child_cnt == 1 && znode->level != 0) {
2460                        zp = znode;
2461                        zbr = &znode->zbranch[0];
2462                        znode = get_znode(c, znode, 0);
2463                        if (IS_ERR(znode))
2464                                return PTR_ERR(znode);
2465                        znode = dirty_cow_znode(c, zbr);
2466                        if (IS_ERR(znode))
2467                                return PTR_ERR(znode);
2468                        znode->parent = NULL;
2469                        znode->iip = 0;
2470                        if (c->zroot.len) {
2471                                err = insert_old_idx(c, c->zroot.lnum,
2472                                                     c->zroot.offs);
2473                                if (err)
2474                                        return err;
2475                        }
2476                        c->zroot.lnum = zbr->lnum;
2477                        c->zroot.offs = zbr->offs;
2478                        c->zroot.len = zbr->len;
2479                        c->zroot.znode = znode;
2480                        ubifs_assert(!ubifs_zn_obsolete(zp));
2481                        ubifs_assert(ubifs_zn_dirty(zp));
2482                        atomic_long_dec(&c->dirty_zn_cnt);
2483
2484                        if (zp->cnext) {
2485                                __set_bit(OBSOLETE_ZNODE, &zp->flags);
2486                                atomic_long_inc(&c->clean_zn_cnt);
2487                                atomic_long_inc(&ubifs_clean_zn_cnt);
2488                        } else
2489                                kfree(zp);
2490                }
2491        }
2492
2493        return 0;
2494}
2495
2496/**
2497 * ubifs_tnc_remove - remove an index entry of a node.
2498 * @c: UBIFS file-system description object
2499 * @key: key of node
2500 *
2501 * Returns %0 on success or negative error code on failure.
2502 */
2503int ubifs_tnc_remove(struct ubifs_info *c, const union ubifs_key *key)
2504{
2505        int found, n, err = 0;
2506        struct ubifs_znode *znode;
2507
2508        mutex_lock(&c->tnc_mutex);
2509        dbg_tnck(key, "key ");
2510        found = lookup_level0_dirty(c, key, &znode, &n);
2511        if (found < 0) {
2512                err = found;
2513                goto out_unlock;
2514        }
2515        if (found == 1)
2516                err = tnc_delete(c, znode, n);
2517        if (!err)
2518                err = dbg_check_tnc(c, 0);
2519
2520out_unlock:
2521        mutex_unlock(&c->tnc_mutex);
2522        return err;
2523}
2524
2525/**
2526 * ubifs_tnc_remove_nm - remove an index entry for a "hashed" node.
2527 * @c: UBIFS file-system description object
2528 * @key: key of node
2529 * @nm: directory entry name
2530 *
2531 * Returns %0 on success or negative error code on failure.
2532 */
2533int ubifs_tnc_remove_nm(struct ubifs_info *c, const union ubifs_key *key,
2534                        const struct qstr *nm)
2535{
2536        int n, err;
2537        struct ubifs_znode *znode;
2538
2539        mutex_lock(&c->tnc_mutex);
2540        dbg_tnck(key, "%.*s, key ", nm->len, nm->name);
2541        err = lookup_level0_dirty(c, key, &znode, &n);
2542        if (err < 0)
2543                goto out_unlock;
2544
2545        if (err) {
2546                if (c->replaying)
2547                        err = fallible_resolve_collision(c, key, &znode, &n,
2548                                                         nm, 0);
2549                else
2550                        err = resolve_collision(c, key, &znode, &n, nm);
2551                dbg_tnc("rc returned %d, znode %p, n %d", err, znode, n);
2552                if (err < 0)
2553                        goto out_unlock;
2554                if (err) {
2555                        /* Ensure the znode is dirtied */
2556                        if (znode->cnext || !ubifs_zn_dirty(znode)) {
2557                                znode = dirty_cow_bottom_up(c, znode);
2558                                if (IS_ERR(znode)) {
2559                                        err = PTR_ERR(znode);
2560                                        goto out_unlock;
2561                                }
2562                        }
2563                        err = tnc_delete(c, znode, n);
2564                }
2565        }
2566
2567out_unlock:
2568        if (!err)
2569                err = dbg_check_tnc(c, 0);
2570        mutex_unlock(&c->tnc_mutex);
2571        return err;
2572}
2573
2574/**
2575 * key_in_range - determine if a key falls within a range of keys.
2576 * @c: UBIFS file-system description object
2577 * @key: key to check
2578 * @from_key: lowest key in range
2579 * @to_key: highest key in range
2580 *
2581 * This function returns %1 if the key is in range and %0 otherwise.
2582 */
2583static int key_in_range(struct ubifs_info *c, union ubifs_key *key,
2584                        union ubifs_key *from_key, union ubifs_key *to_key)
2585{
2586        if (keys_cmp(c, key, from_key) < 0)
2587                return 0;
2588        if (keys_cmp(c, key, to_key) > 0)
2589                return 0;
2590        return 1;
2591}
2592
2593/**
2594 * ubifs_tnc_remove_range - remove index entries in range.
2595 * @c: UBIFS file-system description object
2596 * @from_key: lowest key to remove
2597 * @to_key: highest key to remove
2598 *
2599 * This function removes index entries starting at @from_key and ending at
2600 * @to_key.  This function returns zero in case of success and a negative error
2601 * code in case of failure.
2602 */
2603int ubifs_tnc_remove_range(struct ubifs_info *c, union ubifs_key *from_key,
2604                           union ubifs_key *to_key)
2605{
2606        int i, n, k, err = 0;
2607        struct ubifs_znode *znode;
2608        union ubifs_key *key;
2609
2610        mutex_lock(&c->tnc_mutex);
2611        while (1) {
2612                /* Find first level 0 znode that contains keys to remove */
2613                err = ubifs_lookup_level0(c, from_key, &znode, &n);
2614                if (err < 0)
2615                        goto out_unlock;
2616
2617                if (err)
2618                        key = from_key;
2619                else {
2620                        err = tnc_next(c, &znode, &n);
2621                        if (err == -ENOENT) {
2622                                err = 0;
2623                                goto out_unlock;
2624                        }
2625                        if (err < 0)
2626                                goto out_unlock;
2627                        key = &znode->zbranch[n].key;
2628                        if (!key_in_range(c, key, from_key, to_key)) {
2629                                err = 0;
2630                                goto out_unlock;
2631                        }
2632                }
2633
2634                /* Ensure the znode is dirtied */
2635                if (znode->cnext || !ubifs_zn_dirty(znode)) {
2636                        znode = dirty_cow_bottom_up(c, znode);
2637                        if (IS_ERR(znode)) {
2638                                err = PTR_ERR(znode);
2639                                goto out_unlock;
2640                        }
2641                }
2642
2643                /* Remove all keys in range except the first */
2644                for (i = n + 1, k = 0; i < znode->child_cnt; i++, k++) {
2645                        key = &znode->zbranch[i].key;
2646                        if (!key_in_range(c, key, from_key, to_key))
2647                                break;
2648                        lnc_free(&znode->zbranch[i]);
2649                        err = ubifs_add_dirt(c, znode->zbranch[i].lnum,
2650                                             znode->zbranch[i].len);
2651                        if (err) {
2652                                ubifs_dump_znode(c, znode);
2653                                goto out_unlock;
2654                        }
2655                        dbg_tnck(key, "removing key ");
2656                }
2657                if (k) {
2658                        for (i = n + 1 + k; i < znode->child_cnt; i++)
2659                                znode->zbranch[i - k] = znode->zbranch[i];
2660                        znode->child_cnt -= k;
2661                }
2662
2663                /* Now delete the first */
2664                err = tnc_delete(c, znode, n);
2665                if (err)
2666                        goto out_unlock;
2667        }
2668
2669out_unlock:
2670        if (!err)
2671                err = dbg_check_tnc(c, 0);
2672        mutex_unlock(&c->tnc_mutex);
2673        return err;
2674}
2675
2676/**
2677 * ubifs_tnc_remove_ino - remove an inode from TNC.
2678 * @c: UBIFS file-system description object
2679 * @inum: inode number to remove
2680 *
2681 * This function remove inode @inum and all the extended attributes associated
2682 * with the anode from TNC and returns zero in case of success or a negative
2683 * error code in case of failure.
2684 */
2685int ubifs_tnc_remove_ino(struct ubifs_info *c, ino_t inum)
2686{
2687        union ubifs_key key1, key2;
2688        struct ubifs_dent_node *xent, *pxent = NULL;
2689        struct qstr nm = { .name = NULL };
2690
2691        dbg_tnc("ino %lu", (unsigned long)inum);
2692
2693        /*
2694         * Walk all extended attribute entries and remove them together with
2695         * corresponding extended attribute inodes.
2696         */
2697        lowest_xent_key(c, &key1, inum);
2698        while (1) {
2699                ino_t xattr_inum;
2700                int err;
2701
2702                xent = ubifs_tnc_next_ent(c, &key1, &nm);
2703                if (IS_ERR(xent)) {
2704                        err = PTR_ERR(xent);
2705                        if (err == -ENOENT)
2706                                break;
2707                        return err;
2708                }
2709
2710                xattr_inum = le64_to_cpu(xent->inum);
2711                dbg_tnc("xent '%s', ino %lu", xent->name,
2712                        (unsigned long)xattr_inum);
2713
2714                nm.name = xent->name;
2715                nm.len = le16_to_cpu(xent->nlen);
2716                err = ubifs_tnc_remove_nm(c, &key1, &nm);
2717                if (err) {
2718                        kfree(xent);
2719                        return err;
2720                }
2721
2722                lowest_ino_key(c, &key1, xattr_inum);
2723                highest_ino_key(c, &key2, xattr_inum);
2724                err = ubifs_tnc_remove_range(c, &key1, &key2);
2725                if (err) {
2726                        kfree(xent);
2727                        return err;
2728                }
2729
2730                kfree(pxent);
2731                pxent = xent;
2732                key_read(c, &xent->key, &key1);
2733        }
2734
2735        kfree(pxent);
2736        lowest_ino_key(c, &key1, inum);
2737        highest_ino_key(c, &key2, inum);
2738
2739        return ubifs_tnc_remove_range(c, &key1, &key2);
2740}
2741
2742/**
2743 * ubifs_tnc_next_ent - walk directory or extended attribute entries.
2744 * @c: UBIFS file-system description object
2745 * @key: key of last entry
2746 * @nm: name of last entry found or %NULL
2747 *
2748 * This function finds and reads the next directory or extended attribute entry
2749 * after the given key (@key) if there is one. @nm is used to resolve
2750 * collisions.
2751 *
2752 * If the name of the current entry is not known and only the key is known,
2753 * @nm->name has to be %NULL. In this case the semantics of this function is a
2754 * little bit different and it returns the entry corresponding to this key, not
2755 * the next one. If the key was not found, the closest "right" entry is
2756 * returned.
2757 *
2758 * If the fist entry has to be found, @key has to contain the lowest possible
2759 * key value for this inode and @name has to be %NULL.
2760 *
2761 * This function returns the found directory or extended attribute entry node
2762 * in case of success, %-ENOENT is returned if no entry was found, and a
2763 * negative error code is returned in case of failure.
2764 */
2765struct ubifs_dent_node *ubifs_tnc_next_ent(struct ubifs_info *c,
2766                                           union ubifs_key *key,
2767                                           const struct qstr *nm)
2768{
2769        int n, err, type = key_type(c, key);
2770        struct ubifs_znode *znode;
2771        struct ubifs_dent_node *dent;
2772        struct ubifs_zbranch *zbr;
2773        union ubifs_key *dkey;
2774
2775        dbg_tnck(key, "%s ", nm->name ? (char *)nm->name : "(lowest)");
2776        ubifs_assert(is_hash_key(c, key));
2777
2778        mutex_lock(&c->tnc_mutex);
2779        err = ubifs_lookup_level0(c, key, &znode, &n);
2780        if (unlikely(err < 0))
2781                goto out_unlock;
2782
2783        if (nm->name) {
2784                if (err) {
2785                        /* Handle collisions */
2786                        err = resolve_collision(c, key, &znode, &n, nm);
2787                        dbg_tnc("rc returned %d, znode %p, n %d",
2788                                err, znode, n);
2789                        if (unlikely(err < 0))
2790                                goto out_unlock;
2791                }
2792
2793                /* Now find next entry */
2794                err = tnc_next(c, &znode, &n);
2795                if (unlikely(err))
2796                        goto out_unlock;
2797        } else {
2798                /*
2799                 * The full name of the entry was not given, in which case the
2800                 * behavior of this function is a little different and it
2801                 * returns current entry, not the next one.
2802                 */
2803                if (!err) {
2804                        /*
2805                         * However, the given key does not exist in the TNC
2806                         * tree and @znode/@n variables contain the closest
2807                         * "preceding" element. Switch to the next one.
2808                         */
2809                        err = tnc_next(c, &znode, &n);
2810                        if (err)
2811                                goto out_unlock;
2812                }
2813        }
2814
2815        zbr = &znode->zbranch[n];
2816        dent = kmalloc(zbr->len, GFP_NOFS);
2817        if (unlikely(!dent)) {
2818                err = -ENOMEM;
2819                goto out_unlock;
2820        }
2821
2822        /*
2823         * The above 'tnc_next()' call could lead us to the next inode, check
2824         * this.
2825         */
2826        dkey = &zbr->key;
2827        if (key_inum(c, dkey) != key_inum(c, key) ||
2828            key_type(c, dkey) != type) {
2829                err = -ENOENT;
2830                goto out_free;
2831        }
2832
2833        err = tnc_read_node_nm(c, zbr, dent);
2834        if (unlikely(err))
2835                goto out_free;
2836
2837        mutex_unlock(&c->tnc_mutex);
2838        return dent;
2839
2840out_free:
2841        kfree(dent);
2842out_unlock:
2843        mutex_unlock(&c->tnc_mutex);
2844        return ERR_PTR(err);
2845}
2846
2847/**
2848 * tnc_destroy_cnext - destroy left-over obsolete znodes from a failed commit.
2849 * @c: UBIFS file-system description object
2850 *
2851 * Destroy left-over obsolete znodes from a failed commit.
2852 */
2853static void tnc_destroy_cnext(struct ubifs_info *c)
2854{
2855        struct ubifs_znode *cnext;
2856
2857        if (!c->cnext)
2858                return;
2859        ubifs_assert(c->cmt_state == COMMIT_BROKEN);
2860        cnext = c->cnext;
2861        do {
2862                struct ubifs_znode *znode = cnext;
2863
2864                cnext = cnext->cnext;
2865                if (ubifs_zn_obsolete(znode))
2866                        kfree(znode);
2867        } while (cnext && cnext != c->cnext);
2868}
2869
2870/**
2871 * ubifs_tnc_close - close TNC subsystem and free all related resources.
2872 * @c: UBIFS file-system description object
2873 */
2874void ubifs_tnc_close(struct ubifs_info *c)
2875{
2876        tnc_destroy_cnext(c);
2877        if (c->zroot.znode) {
2878                long n;
2879
2880                ubifs_destroy_tnc_subtree(c->zroot.znode);
2881                n = atomic_long_read(&c->clean_zn_cnt);
2882                atomic_long_sub(n, &ubifs_clean_zn_cnt);
2883        }
2884        kfree(c->gap_lebs);
2885        kfree(c->ilebs);
2886        destroy_old_idx(c);
2887}
2888
2889/**
2890 * left_znode - get the znode to the left.
2891 * @c: UBIFS file-system description object
2892 * @znode: znode
2893 *
2894 * This function returns a pointer to the znode to the left of @znode or NULL if
2895 * there is not one. A negative error code is returned on failure.
2896 */
2897static struct ubifs_znode *left_znode(struct ubifs_info *c,
2898                                      struct ubifs_znode *znode)
2899{
2900        int level = znode->level;
2901
2902        while (1) {
2903                int n = znode->iip - 1;
2904
2905                /* Go up until we can go left */
2906                znode = znode->parent;
2907                if (!znode)
2908                        return NULL;
2909                if (n >= 0) {
2910                        /* Now go down the rightmost branch to 'level' */
2911                        znode = get_znode(c, znode, n);
2912                        if (IS_ERR(znode))
2913                                return znode;
2914                        while (znode->level != level) {
2915                                n = znode->child_cnt - 1;
2916                                znode = get_znode(c, znode, n);
2917                                if (IS_ERR(znode))
2918                                        return znode;
2919                        }
2920                        break;
2921                }
2922        }
2923        return znode;
2924}
2925
2926/**
2927 * right_znode - get the znode to the right.
2928 * @c: UBIFS file-system description object
2929 * @znode: znode
2930 *
2931 * This function returns a pointer to the znode to the right of @znode or NULL
2932 * if there is not one. A negative error code is returned on failure.
2933 */
2934static struct ubifs_znode *right_znode(struct ubifs_info *c,
2935                                       struct ubifs_znode *znode)
2936{
2937        int level = znode->level;
2938
2939        while (1) {
2940                int n = znode->iip + 1;
2941
2942                /* Go up until we can go right */
2943                znode = znode->parent;
2944                if (!znode)
2945                        return NULL;
2946                if (n < znode->child_cnt) {
2947                        /* Now go down the leftmost branch to 'level' */
2948                        znode = get_znode(c, znode, n);
2949                        if (IS_ERR(znode))
2950                                return znode;
2951                        while (znode->level != level) {
2952                                znode = get_znode(c, znode, 0);
2953                                if (IS_ERR(znode))
2954                                        return znode;
2955                        }
2956                        break;
2957                }
2958        }
2959        return znode;
2960}
2961
2962/**
2963 * lookup_znode - find a particular indexing node from TNC.
2964 * @c: UBIFS file-system description object
2965 * @key: index node key to lookup
2966 * @level: index node level
2967 * @lnum: index node LEB number
2968 * @offs: index node offset
2969 *
2970 * This function searches an indexing node by its first key @key and its
2971 * address @lnum:@offs. It looks up the indexing tree by pulling all indexing
2972 * nodes it traverses to TNC. This function is called for indexing nodes which
2973 * were found on the media by scanning, for example when garbage-collecting or
2974 * when doing in-the-gaps commit. This means that the indexing node which is
2975 * looked for does not have to have exactly the same leftmost key @key, because
2976 * the leftmost key may have been changed, in which case TNC will contain a
2977 * dirty znode which still refers the same @lnum:@offs. This function is clever
2978 * enough to recognize such indexing nodes.
2979 *
2980 * Note, if a znode was deleted or changed too much, then this function will
2981 * not find it. For situations like this UBIFS has the old index RB-tree
2982 * (indexed by @lnum:@offs).
2983 *
2984 * This function returns a pointer to the znode found or %NULL if it is not
2985 * found. A negative error code is returned on failure.
2986 */
2987static struct ubifs_znode *lookup_znode(struct ubifs_info *c,
2988                                        union ubifs_key *key, int level,
2989                                        int lnum, int offs)
2990{
2991        struct ubifs_znode *znode, *zn;
2992        int n, nn;
2993
2994        ubifs_assert(key_type(c, key) < UBIFS_INVALID_KEY);
2995
2996        /*
2997         * The arguments have probably been read off flash, so don't assume
2998         * they are valid.
2999         */
3000        if (level < 0)
3001                return ERR_PTR(-EINVAL);
3002
3003        /* Get the root znode */
3004        znode = c->zroot.znode;
3005        if (!znode) {
3006                znode = ubifs_load_znode(c, &c->zroot, NULL, 0);
3007                if (IS_ERR(znode))
3008                        return znode;
3009        }
3010        /* Check if it is the one we are looking for */
3011        if (c->zroot.lnum == lnum && c->zroot.offs == offs)
3012                return znode;
3013        /* Descend to the parent level i.e. (level + 1) */
3014        if (level >= znode->level)
3015                return NULL;
3016        while (1) {
3017                ubifs_search_zbranch(c, znode, key, &n);
3018                if (n < 0) {
3019                        /*
3020                         * We reached a znode where the leftmost key is greater
3021                         * than the key we are searching for. This is the same
3022                         * situation as the one described in a huge comment at
3023                         * the end of the 'ubifs_lookup_level0()' function. And
3024                         * for exactly the same reasons we have to try to look
3025                         * left before giving up.
3026                         */
3027                        znode = left_znode(c, znode);
3028                        if (!znode)
3029                                return NULL;
3030                        if (IS_ERR(znode))
3031                                return znode;
3032                        ubifs_search_zbranch(c, znode, key, &n);
3033                        ubifs_assert(n >= 0);
3034                }
3035                if (znode->level == level + 1)
3036                        break;
3037                znode = get_znode(c, znode, n);
3038                if (IS_ERR(znode))
3039                        return znode;
3040        }
3041        /* Check if the child is the one we are looking for */
3042        if (znode->zbranch[n].lnum == lnum && znode->zbranch[n].offs == offs)
3043                return get_znode(c, znode, n);
3044        /* If the key is unique, there is nowhere else to look */
3045        if (!is_hash_key(c, key))
3046                return NULL;
3047        /*
3048         * The key is not unique and so may be also in the znodes to either
3049         * side.
3050         */
3051        zn = znode;
3052        nn = n;
3053        /* Look left */
3054        while (1) {
3055                /* Move one branch to the left */
3056                if (n)
3057                        n -= 1;
3058                else {
3059                        znode = left_znode(c, znode);
3060                        if (!znode)
3061                                break;
3062                        if (IS_ERR(znode))
3063                                return znode;
3064                        n = znode->child_cnt - 1;
3065                }
3066                /* Check it */
3067                if (znode->zbranch[n].lnum == lnum &&
3068                    znode->zbranch[n].offs == offs)
3069                        return get_znode(c, znode, n);
3070                /* Stop if the key is less than the one we are looking for */
3071                if (keys_cmp(c, &znode->zbranch[n].key, key) < 0)
3072                        break;
3073        }
3074        /* Back to the middle */
3075        znode = zn;
3076        n = nn;
3077        /* Look right */
3078        while (1) {
3079                /* Move one branch to the right */
3080                if (++n >= znode->child_cnt) {
3081                        znode = right_znode(c, znode);
3082                        if (!znode)
3083                                break;
3084                        if (IS_ERR(znode))
3085                                return znode;
3086                        n = 0;
3087                }
3088                /* Check it */
3089                if (znode->zbranch[n].lnum == lnum &&
3090                    znode->zbranch[n].offs == offs)
3091                        return get_znode(c, znode, n);
3092                /* Stop if the key is greater than the one we are looking for */
3093                if (keys_cmp(c, &znode->zbranch[n].key, key) > 0)
3094                        break;
3095        }
3096        return NULL;
3097}
3098
3099/**
3100 * is_idx_node_in_tnc - determine if an index node is in the TNC.
3101 * @c: UBIFS file-system description object
3102 * @key: key of index node
3103 * @level: index node level
3104 * @lnum: LEB number of index node
3105 * @offs: offset of index node
3106 *
3107 * This function returns %0 if the index node is not referred to in the TNC, %1
3108 * if the index node is referred to in the TNC and the corresponding znode is
3109 * dirty, %2 if an index node is referred to in the TNC and the corresponding
3110 * znode is clean, and a negative error code in case of failure.
3111 *
3112 * Note, the @key argument has to be the key of the first child. Also note,
3113 * this function relies on the fact that 0:0 is never a valid LEB number and
3114 * offset for a main-area node.
3115 */
3116int is_idx_node_in_tnc(struct ubifs_info *c, union ubifs_key *key, int level,
3117                       int lnum, int offs)
3118{
3119        struct ubifs_znode *znode;
3120
3121        znode = lookup_znode(c, key, level, lnum, offs);
3122        if (!znode)
3123                return 0;
3124        if (IS_ERR(znode))
3125                return PTR_ERR(znode);
3126
3127        return ubifs_zn_dirty(znode) ? 1 : 2;
3128}
3129
3130/**
3131 * is_leaf_node_in_tnc - determine if a non-indexing not is in the TNC.
3132 * @c: UBIFS file-system description object
3133 * @key: node key
3134 * @lnum: node LEB number
3135 * @offs: node offset
3136 *
3137 * This function returns %1 if the node is referred to in the TNC, %0 if it is
3138 * not, and a negative error code in case of failure.
3139 *
3140 * Note, this function relies on the fact that 0:0 is never a valid LEB number
3141 * and offset for a main-area node.
3142 */
3143static int is_leaf_node_in_tnc(struct ubifs_info *c, union ubifs_key *key,
3144                               int lnum, int offs)
3145{
3146        struct ubifs_zbranch *zbr;
3147        struct ubifs_znode *znode, *zn;
3148        int n, found, err, nn;
3149        const int unique = !is_hash_key(c, key);
3150
3151        found = ubifs_lookup_level0(c, key, &znode, &n);
3152        if (found < 0)
3153                return found; /* Error code */
3154        if (!found)
3155                return 0;
3156        zbr = &znode->zbranch[n];
3157        if (lnum == zbr->lnum && offs == zbr->offs)
3158                return 1; /* Found it */
3159        if (unique)
3160                return 0;
3161        /*
3162         * Because the key is not unique, we have to look left
3163         * and right as well
3164         */
3165        zn = znode;
3166        nn = n;
3167        /* Look left */
3168        while (1) {
3169                err = tnc_prev(c, &znode, &n);
3170                if (err == -ENOENT)
3171                        break;
3172                if (err)
3173                        return err;
3174                if (keys_cmp(c, key, &znode->zbranch[n].key))
3175                        break;
3176                zbr = &znode->zbranch[n];
3177                if (lnum == zbr->lnum && offs == zbr->offs)
3178                        return 1; /* Found it */
3179        }
3180        /* Look right */
3181        znode = zn;
3182        n = nn;
3183        while (1) {
3184                err = tnc_next(c, &znode, &n);
3185                if (err) {
3186                        if (err == -ENOENT)
3187                                return 0;
3188                        return err;
3189                }
3190                if (keys_cmp(c, key, &znode->zbranch[n].key))
3191                        break;
3192                zbr = &znode->zbranch[n];
3193                if (lnum == zbr->lnum && offs == zbr->offs)
3194                        return 1; /* Found it */
3195        }
3196        return 0;
3197}
3198
3199/**
3200 * ubifs_tnc_has_node - determine whether a node is in the TNC.
3201 * @c: UBIFS file-system description object
3202 * @key: node key
3203 * @level: index node level (if it is an index node)
3204 * @lnum: node LEB number
3205 * @offs: node offset
3206 * @is_idx: non-zero if the node is an index node
3207 *
3208 * This function returns %1 if the node is in the TNC, %0 if it is not, and a
3209 * negative error code in case of failure. For index nodes, @key has to be the
3210 * key of the first child. An index node is considered to be in the TNC only if
3211 * the corresponding znode is clean or has not been loaded.
3212 */
3213int ubifs_tnc_has_node(struct ubifs_info *c, union ubifs_key *key, int level,
3214                       int lnum, int offs, int is_idx)
3215{
3216        int err;
3217
3218        mutex_lock(&c->tnc_mutex);
3219        if (is_idx) {
3220                err = is_idx_node_in_tnc(c, key, level, lnum, offs);
3221                if (err < 0)
3222                        goto out_unlock;
3223                if (err == 1)
3224                        /* The index node was found but it was dirty */
3225                        err = 0;
3226                else if (err == 2)
3227                        /* The index node was found and it was clean */
3228                        err = 1;
3229                else
3230                        BUG_ON(err != 0);
3231        } else
3232                err = is_leaf_node_in_tnc(c, key, lnum, offs);
3233
3234out_unlock:
3235        mutex_unlock(&c->tnc_mutex);
3236        return err;
3237}
3238
3239/**
3240 * ubifs_dirty_idx_node - dirty an index node.
3241 * @c: UBIFS file-system description object
3242 * @key: index node key
3243 * @level: index node level
3244 * @lnum: index node LEB number
3245 * @offs: index node offset
3246 *
3247 * This function loads and dirties an index node so that it can be garbage
3248 * collected. The @key argument has to be the key of the first child. This
3249 * function relies on the fact that 0:0 is never a valid LEB number and offset
3250 * for a main-area node. Returns %0 on success and a negative error code on
3251 * failure.
3252 */
3253int ubifs_dirty_idx_node(struct ubifs_info *c, union ubifs_key *key, int level,
3254                         int lnum, int offs)
3255{
3256        struct ubifs_znode *znode;
3257        int err = 0;
3258
3259        mutex_lock(&c->tnc_mutex);
3260        znode = lookup_znode(c, key, level, lnum, offs);
3261        if (!znode)
3262                goto out_unlock;
3263        if (IS_ERR(znode)) {
3264                err = PTR_ERR(znode);
3265                goto out_unlock;
3266        }
3267        znode = dirty_cow_bottom_up(c, znode);
3268        if (IS_ERR(znode)) {
3269                err = PTR_ERR(znode);
3270                goto out_unlock;
3271        }
3272
3273out_unlock:
3274        mutex_unlock(&c->tnc_mutex);
3275        return err;
3276}
3277
3278/**
3279 * dbg_check_inode_size - check if inode size is correct.
3280 * @c: UBIFS file-system description object
3281 * @inum: inode number
3282 * @size: inode size
3283 *
3284 * This function makes sure that the inode size (@size) is correct and it does
3285 * not have any pages beyond @size. Returns zero if the inode is OK, %-EINVAL
3286 * if it has a data page beyond @size, and other negative error code in case of
3287 * other errors.
3288 */
3289int dbg_check_inode_size(struct ubifs_info *c, const struct inode *inode,
3290                         loff_t size)
3291{
3292        int err, n;
3293        union ubifs_key from_key, to_key, *key;
3294        struct ubifs_znode *znode;
3295        unsigned int block;
3296
3297        if (!S_ISREG(inode->i_mode))
3298                return 0;
3299        if (!dbg_is_chk_gen(c))
3300                return 0;
3301
3302        block = (size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
3303        data_key_init(c, &from_key, inode->i_ino, block);
3304        highest_data_key(c, &to_key, inode->i_ino);
3305
3306        mutex_lock(&c->tnc_mutex);
3307        err = ubifs_lookup_level0(c, &from_key, &znode, &n);
3308        if (err < 0)
3309                goto out_unlock;
3310
3311        if (err) {
3312                err = -EINVAL;
3313                key = &from_key;
3314                goto out_dump;
3315        }
3316
3317        err = tnc_next(c, &znode, &n);
3318        if (err == -ENOENT) {
3319                err = 0;
3320                goto out_unlock;
3321        }
3322        if (err < 0)
3323                goto out_unlock;
3324
3325        ubifs_assert(err == 0);
3326        key = &znode->zbranch[n].key;
3327        if (!key_in_range(c, key, &from_key, &to_key))
3328                goto out_unlock;
3329
3330out_dump:
3331        block = key_block(c, key);
3332        ubifs_err("inode %lu has size %lld, but there are data at offset %lld",
3333                  (unsigned long)inode->i_ino, size,
3334                  ((loff_t)block) << UBIFS_BLOCK_SHIFT);
3335        mutex_unlock(&c->tnc_mutex);
3336        ubifs_dump_inode(c, inode);
3337        dump_stack();
3338        return -EINVAL;
3339
3340out_unlock:
3341        mutex_unlock(&c->tnc_mutex);
3342        return err;
3343}
3344
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