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-rw-r--r--fs/ubifs/tnc_misc.c494
1 files changed, 494 insertions, 0 deletions
diff --git a/fs/ubifs/tnc_misc.c b/fs/ubifs/tnc_misc.c
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+++ b/fs/ubifs/tnc_misc.c
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+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Authors: Adrian Hunter
+ * Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * This file contains miscelanious TNC-related functions shared betweend
+ * different files. This file does not form any logically separate TNC
+ * sub-system. The file was created because there is a lot of TNC code and
+ * putting it all in one file would make that file too big and unreadable.
+ */
+
+#include "ubifs.h"
+
+/**
+ * ubifs_tnc_levelorder_next - next TNC tree element in levelorder traversal.
+ * @zr: root of the subtree to traverse
+ * @znode: previous znode
+ *
+ * This function implements levelorder TNC traversal. The LNC is ignored.
+ * Returns the next element or %NULL if @znode is already the last one.
+ */
+struct ubifs_znode *ubifs_tnc_levelorder_next(struct ubifs_znode *zr,
+ struct ubifs_znode *znode)
+{
+ int level, iip, level_search = 0;
+ struct ubifs_znode *zn;
+
+ ubifs_assert(zr);
+
+ if (unlikely(!znode))
+ return zr;
+
+ if (unlikely(znode == zr)) {
+ if (znode->level == 0)
+ return NULL;
+ return ubifs_tnc_find_child(zr, 0);
+ }
+
+ level = znode->level;
+
+ iip = znode->iip;
+ while (1) {
+ ubifs_assert(znode->level <= zr->level);
+
+ /*
+ * First walk up until there is a znode with next branch to
+ * look at.
+ */
+ while (znode->parent != zr && iip >= znode->parent->child_cnt) {
+ znode = znode->parent;
+ iip = znode->iip;
+ }
+
+ if (unlikely(znode->parent == zr &&
+ iip >= znode->parent->child_cnt)) {
+ /* This level is done, switch to the lower one */
+ level -= 1;
+ if (level_search || level < 0)
+ /*
+ * We were already looking for znode at lower
+ * level ('level_search'). As we are here
+ * again, it just does not exist. Or all levels
+ * were finished ('level < 0').
+ */
+ return NULL;
+
+ level_search = 1;
+ iip = -1;
+ znode = ubifs_tnc_find_child(zr, 0);
+ ubifs_assert(znode);
+ }
+
+ /* Switch to the next index */
+ zn = ubifs_tnc_find_child(znode->parent, iip + 1);
+ if (!zn) {
+ /* No more children to look at, we have walk up */
+ iip = znode->parent->child_cnt;
+ continue;
+ }
+
+ /* Walk back down to the level we came from ('level') */
+ while (zn->level != level) {
+ znode = zn;
+ zn = ubifs_tnc_find_child(zn, 0);
+ if (!zn) {
+ /*
+ * This path is not too deep so it does not
+ * reach 'level'. Try next path.
+ */
+ iip = znode->iip;
+ break;
+ }
+ }
+
+ if (zn) {
+ ubifs_assert(zn->level >= 0);
+ return zn;
+ }
+ }
+}
+
+/**
+ * ubifs_search_zbranch - search znode branch.
+ * @c: UBIFS file-system description object
+ * @znode: znode to search in
+ * @key: key to search for
+ * @n: znode branch slot number is returned here
+ *
+ * This is a helper function which search branch with key @key in @znode using
+ * binary search. The result of the search may be:
+ * o exact match, then %1 is returned, and the slot number of the branch is
+ * stored in @n;
+ * o no exact match, then %0 is returned and the slot number of the left
+ * closest branch is returned in @n; the slot if all keys in this znode are
+ * greater than @key, then %-1 is returned in @n.
+ */
+int ubifs_search_zbranch(const struct ubifs_info *c,
+ const struct ubifs_znode *znode,
+ const union ubifs_key *key, int *n)
+{
+ int beg = 0, end = znode->child_cnt, uninitialized_var(mid);
+ int uninitialized_var(cmp);
+ const struct ubifs_zbranch *zbr = &znode->zbranch[0];
+
+ ubifs_assert(end > beg);
+
+ while (end > beg) {
+ mid = (beg + end) >> 1;
+ cmp = keys_cmp(c, key, &zbr[mid].key);
+ if (cmp > 0)
+ beg = mid + 1;
+ else if (cmp < 0)
+ end = mid;
+ else {
+ *n = mid;
+ return 1;
+ }
+ }
+
+ *n = end - 1;
+
+ /* The insert point is after *n */
+ ubifs_assert(*n >= -1 && *n < znode->child_cnt);
+ if (*n == -1)
+ ubifs_assert(keys_cmp(c, key, &zbr[0].key) < 0);
+ else
+ ubifs_assert(keys_cmp(c, key, &zbr[*n].key) > 0);
+ if (*n + 1 < znode->child_cnt)
+ ubifs_assert(keys_cmp(c, key, &zbr[*n + 1].key) < 0);
+
+ return 0;
+}
+
+/**
+ * ubifs_tnc_postorder_first - find first znode to do postorder tree traversal.
+ * @znode: znode to start at (root of the sub-tree to traverse)
+ *
+ * Find the lowest leftmost znode in a subtree of the TNC tree. The LNC is
+ * ignored.
+ */
+struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode)
+{
+ if (unlikely(!znode))
+ return NULL;
+
+ while (znode->level > 0) {
+ struct ubifs_znode *child;
+
+ child = ubifs_tnc_find_child(znode, 0);
+ if (!child)
+ return znode;
+ znode = child;
+ }
+
+ return znode;
+}
+
+/**
+ * ubifs_tnc_postorder_next - next TNC tree element in postorder traversal.
+ * @znode: previous znode
+ *
+ * This function implements postorder TNC traversal. The LNC is ignored.
+ * Returns the next element or %NULL if @znode is already the last one.
+ */
+struct ubifs_znode *ubifs_tnc_postorder_next(struct ubifs_znode *znode)
+{
+ struct ubifs_znode *zn;
+
+ ubifs_assert(znode);
+ if (unlikely(!znode->parent))
+ return NULL;
+
+ /* Switch to the next index in the parent */
+ zn = ubifs_tnc_find_child(znode->parent, znode->iip + 1);
+ if (!zn)
+ /* This is in fact the last child, return parent */
+ return znode->parent;
+
+ /* Go to the first znode in this new subtree */
+ return ubifs_tnc_postorder_first(zn);
+}
+
+/**
+ * ubifs_destroy_tnc_subtree - destroy all znodes connected to a subtree.
+ * @znode: znode defining subtree to destroy
+ *
+ * This function destroys subtree of the TNC tree. Returns number of clean
+ * znodes in the subtree.
+ */
+long ubifs_destroy_tnc_subtree(struct ubifs_znode *znode)
+{
+ struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
+ long clean_freed = 0;
+ int n;
+
+ ubifs_assert(zn);
+ while (1) {
+ for (n = 0; n < zn->child_cnt; n++) {
+ if (!zn->zbranch[n].znode)
+ continue;
+
+ if (zn->level > 0 &&
+ !ubifs_zn_dirty(zn->zbranch[n].znode))
+ clean_freed += 1;
+
+ cond_resched();
+ kfree(zn->zbranch[n].znode);
+ }
+
+ if (zn == znode) {
+ if (!ubifs_zn_dirty(zn))
+ clean_freed += 1;
+ kfree(zn);
+ return clean_freed;
+ }
+
+ zn = ubifs_tnc_postorder_next(zn);
+ }
+}
+
+/**
+ * read_znode - read an indexing node from flash and fill znode.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB of the indexing node to read
+ * @offs: node offset
+ * @len: node length
+ * @znode: znode to read to
+ *
+ * This function reads an indexing node from the flash media and fills znode
+ * with the read data. Returns zero in case of success and a negative error
+ * code in case of failure. The read indexing node is validated and if anything
+ * is wrong with it, this function prints complaint messages and returns
+ * %-EINVAL.
+ */
+static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
+ struct ubifs_znode *znode)
+{
+ int i, err, type, cmp;
+ struct ubifs_idx_node *idx;
+
+ idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
+ if (!idx)
+ return -ENOMEM;
+
+ err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
+ if (err < 0) {
+ kfree(idx);
+ return err;
+ }
+
+ znode->child_cnt = le16_to_cpu(idx->child_cnt);
+ znode->level = le16_to_cpu(idx->level);
+
+ dbg_tnc("LEB %d:%d, level %d, %d branch",
+ lnum, offs, znode->level, znode->child_cnt);
+
+ if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
+ ubifs_err(c, "current fanout %d, branch count %d",
+ c->fanout, znode->child_cnt);
+ ubifs_err(c, "max levels %d, znode level %d",
+ UBIFS_MAX_LEVELS, znode->level);
+ err = 1;
+ goto out_dump;
+ }
+
+ for (i = 0; i < znode->child_cnt; i++) {
+ const struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
+ struct ubifs_zbranch *zbr = &znode->zbranch[i];
+
+ key_read(c, &br->key, &zbr->key);
+ zbr->lnum = le32_to_cpu(br->lnum);
+ zbr->offs = le32_to_cpu(br->offs);
+ zbr->len = le32_to_cpu(br->len);
+ zbr->znode = NULL;
+
+ /* Validate branch */
+
+ if (zbr->lnum < c->main_first ||
+ zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
+ zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
+ ubifs_err(c, "bad branch %d", i);
+ err = 2;
+ goto out_dump;
+ }
+
+ switch (key_type(c, &zbr->key)) {
+ case UBIFS_INO_KEY:
+ case UBIFS_DATA_KEY:
+ case UBIFS_DENT_KEY:
+ case UBIFS_XENT_KEY:
+ break;
+ default:
+ ubifs_err(c, "bad key type at slot %d: %d",
+ i, key_type(c, &zbr->key));
+ err = 3;
+ goto out_dump;
+ }
+
+ if (znode->level)
+ continue;
+
+ type = key_type(c, &zbr->key);
+ if (c->ranges[type].max_len == 0) {
+ if (zbr->len != c->ranges[type].len) {
+ ubifs_err(c, "bad target node (type %d) length (%d)",
+ type, zbr->len);
+ ubifs_err(c, "have to be %d", c->ranges[type].len);
+ err = 4;
+ goto out_dump;
+ }
+ } else if (zbr->len < c->ranges[type].min_len ||
+ zbr->len > c->ranges[type].max_len) {
+ ubifs_err(c, "bad target node (type %d) length (%d)",
+ type, zbr->len);
+ ubifs_err(c, "have to be in range of %d-%d",
+ c->ranges[type].min_len,
+ c->ranges[type].max_len);
+ err = 5;
+ goto out_dump;
+ }
+ }
+
+ /*
+ * Ensure that the next key is greater or equivalent to the
+ * previous one.
+ */
+ for (i = 0; i < znode->child_cnt - 1; i++) {
+ const union ubifs_key *key1, *key2;
+
+ key1 = &znode->zbranch[i].key;
+ key2 = &znode->zbranch[i + 1].key;
+
+ cmp = keys_cmp(c, key1, key2);
+ if (cmp > 0) {
+ ubifs_err(c, "bad key order (keys %d and %d)", i, i + 1);
+ err = 6;
+ goto out_dump;
+ } else if (cmp == 0 && !is_hash_key(c, key1)) {
+ /* These can only be keys with colliding hash */
+ ubifs_err(c, "keys %d and %d are not hashed but equivalent",
+ i, i + 1);
+ err = 7;
+ goto out_dump;
+ }
+ }
+
+ kfree(idx);
+ return 0;
+
+out_dump:
+ ubifs_err(c, "bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
+ ubifs_dump_node(c, idx);
+ kfree(idx);
+ return -EINVAL;
+}
+
+/**
+ * ubifs_load_znode - load znode to TNC cache.
+ * @c: UBIFS file-system description object
+ * @zbr: znode branch
+ * @parent: znode's parent
+ * @iip: index in parent
+ *
+ * This function loads znode pointed to by @zbr into the TNC cache and
+ * returns pointer to it in case of success and a negative error code in case
+ * of failure.
+ */
+struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
+ struct ubifs_zbranch *zbr,
+ struct ubifs_znode *parent, int iip)
+{
+ int err;
+ struct ubifs_znode *znode;
+
+ ubifs_assert(!zbr->znode);
+ /*
+ * A slab cache is not presently used for znodes because the znode size
+ * depends on the fanout which is stored in the superblock.
+ */
+ znode = kzalloc(c->max_znode_sz, GFP_NOFS);
+ if (!znode)
+ return ERR_PTR(-ENOMEM);
+
+ err = read_znode(c, zbr->lnum, zbr->offs, zbr->len, znode);
+ if (err)
+ goto out;
+
+ atomic_long_inc(&c->clean_zn_cnt);
+
+ /*
+ * Increment the global clean znode counter as well. It is OK that
+ * global and per-FS clean znode counters may be inconsistent for some
+ * short time (because we might be preempted at this point), the global
+ * one is only used in shrinker.
+ */
+ atomic_long_inc(&ubifs_clean_zn_cnt);
+
+ zbr->znode = znode;
+ znode->parent = parent;
+ znode->time = get_seconds();
+ znode->iip = iip;
+
+ return znode;
+
+out:
+ kfree(znode);
+ return ERR_PTR(err);
+}
+
+/**
+ * ubifs_tnc_read_node - read a leaf node from the flash media.
+ * @c: UBIFS file-system description object
+ * @zbr: key and position of the node
+ * @node: node is returned here
+ *
+ * This function reads a node defined by @zbr from the flash media. Returns
+ * zero in case of success or a negative negative error code in case of
+ * failure.
+ */
+int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
+ void *node)
+{
+ union ubifs_key key1, *key = &zbr->key;
+ int err, type = key_type(c, key);
+ struct ubifs_wbuf *wbuf;
+
+ /*
+ * 'zbr' has to point to on-flash node. The node may sit in a bud and
+ * may even be in a write buffer, so we have to take care about this.
+ */
+ wbuf = ubifs_get_wbuf(c, zbr->lnum);
+ if (wbuf)
+ err = ubifs_read_node_wbuf(wbuf, node, type, zbr->len,
+ zbr->lnum, zbr->offs);
+ else
+ err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum,
+ zbr->offs);
+
+ if (err) {
+ dbg_tnck(key, "key ");
+ return err;
+ }
+
+ /* Make sure the key of the read node is correct */
+ key_read(c, node + UBIFS_KEY_OFFSET, &key1);
+ if (!keys_eq(c, key, &key1)) {
+ ubifs_err(c, "bad key in node at LEB %d:%d",
+ zbr->lnum, zbr->offs);
+ dbg_tnck(key, "looked for key ");
+ dbg_tnck(&key1, "but found node's key ");
+ ubifs_dump_node(c, node);
+ return -EINVAL;
+ }
+
+ return 0;
+}
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