| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <1211810743-18936-16-git-send-email-Artem.Bityutskiy@nokia.com>
Date: Mon, 26 May 2008 17:05:29 +0300
From: Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Adrian Hunter <ext-adrian.hunter@...ia.com>,
Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
Subject: [PATCH take 3 15/29] UBIFS: add TNC implementation
TNC - tree node cache - the central UBIFS entity. It is basically
in-RAM cache of the on-flash indexing B-tree. But TNC also indexes
the journal, so that they are not always equivalent.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@...ia.com>
---
fs/ubifs/tnc.c | 3330 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 3330 insertions(+), 0 deletions(-)
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
new file mode 100644
index 0000000..5fd1480
--- /dev/null
+++ b/fs/ubifs/tnc.c
@@ -0,0 +1,3330 @@
+/*
+ * 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 implements TNC (Tree Node Cache) which caches indexing nodes of
+ * the UBIFS B-tree.
+ *
+ * At the moment the locking rules of the TNC tree are quite simple and
+ * straightforward. We just have a mutex and lock it when we traverse the
+ * tree. If a znode is not in memory, we read it from flash while still having
+ * the mutex locked.
+ */
+
+#include <linux/crc32.h>
+#include "ubifs.h"
+
+/*
+ * Returned codes of 'matches_name()' and 'fallible_matches_name()' functions.
+ * @NAME_LESS: name corresponding to the first argument is less than second
+ * @NAME_MATCHES: names match
+ * @NAME_GREATER: name corresponding to the second argument is greater than
+ * first
+ * @NOT_ON_MEDIA: node referred by zbranch does not exist on the media
+ *
+ * These constants were introduce to improve readability.
+ */
+enum {
+ NAME_LESS = 0,
+ NAME_MATCHES = 1,
+ NAME_GREATER = 2,
+ NOT_ON_MEDIA = 3,
+};
+
+/**
+ * insert_old_idx - record an index node obsoleted since the last commit start.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number of obsoleted index node
+ * @offs: offset of obsoleted index node
+ *
+ * Returns %0 on success, and a negative error code on failure.
+ *
+ * For recovery, there must always be a complete intact version of the index on
+ * flash at all times. That is called the "old index". It is the index as at the
+ * time of the last successful commit. Many of the index nodes in the old index
+ * may be dirty, but they must not be erased until the next successful commit
+ * (at which point that index becomes the old index).
+ *
+ * That means that the garbage collection and the in-the-gaps method of
+ * committing must be able to determine if an index node is in the old index.
+ * Most of the old index nodes can be found by looking up the TNC using the
+ * 'lookup_znode()' function. However, some of the old index nodes may have
+ * been deleted from the current index or may have been changed so much that
+ * they cannot be easily found. In those cases, an entry is added to an RB-tree.
+ * That is what this function does. The RB-tree is ordered by LEB number and
+ * offset because they uniquely identify the old index node.
+ */
+static int insert_old_idx(struct ubifs_info *c, int lnum, int offs)
+{
+ struct ubifs_old_idx *old_idx, *o;
+ struct rb_node **p, *parent = NULL;
+
+ old_idx = kmalloc(sizeof(struct ubifs_old_idx), GFP_NOFS);
+ if (unlikely(!old_idx))
+ return -ENOMEM;
+ old_idx->lnum = lnum;
+ old_idx->offs = offs;
+
+ p = &c->old_idx.rb_node;
+ while (*p) {
+ parent = *p;
+ o = rb_entry(parent, struct ubifs_old_idx, rb);
+ if (lnum < o->lnum)
+ p = &(*p)->rb_left;
+ else if (lnum > o->lnum)
+ p = &(*p)->rb_right;
+ else if (offs < o->offs)
+ p = &(*p)->rb_left;
+ else if (offs > o->offs)
+ p = &(*p)->rb_right;
+ else {
+ ubifs_err("old idx added twice!");
+ kfree(old_idx);
+ return 0;
+ }
+ }
+ rb_link_node(&old_idx->rb, parent, p);
+ rb_insert_color(&old_idx->rb, &c->old_idx);
+ return 0;
+}
+
+/**
+ * insert_old_idx_znode - record a znode obsoleted since last commit start.
+ * @c: UBIFS file-system description object
+ * @znode: znode of obsoleted index node
+ *
+ * Returns %0 on success, and a negative error code on failure.
+ */
+int insert_old_idx_znode(struct ubifs_info *c, struct ubifs_znode *znode)
+{
+ if (znode->parent) {
+ struct ubifs_zbranch *zbr;
+
+ zbr = &znode->parent->zbranch[znode->iip];
+ if (zbr->len)
+ return insert_old_idx(c, zbr->lnum, zbr->offs);
+ } else
+ if (c->zroot.len)
+ return insert_old_idx(c, c->zroot.lnum,
+ c->zroot.offs);
+ return 0;
+}
+
+/**
+ * ins_clr_old_idx_znode - record a znode obsoleted since last commit start.
+ * @c: UBIFS file-system description object
+ * @znode: znode of obsoleted index node
+ *
+ * Returns %0 on success, and a negative error code on failure.
+ */
+static int ins_clr_old_idx_znode(struct ubifs_info *c,
+ struct ubifs_znode *znode)
+{
+ int err;
+
+ if (znode->parent) {
+ struct ubifs_zbranch *zbr;
+
+ zbr = &znode->parent->zbranch[znode->iip];
+ if (zbr->len) {
+ err = insert_old_idx(c, zbr->lnum, zbr->offs);
+ if (err)
+ return err;
+ zbr->lnum = 0;
+ zbr->offs = 0;
+ zbr->len = 0;
+ }
+ } else
+ if (c->zroot.len) {
+ err = insert_old_idx(c, c->zroot.lnum, c->zroot.offs);
+ if (err)
+ return err;
+ c->zroot.lnum = 0;
+ c->zroot.offs = 0;
+ c->zroot.len = 0;
+ }
+ return 0;
+}
+
+/**
+ * destroy_old_idx - destroy the old_idx RB-tree.
+ * @c: UBIFS file-system description object
+ *
+ * During start commit, the old_idx RB-tree is used to avoid overwriting index
+ * nodes that were in the index last commit but have since been deleted. This
+ * is necessary for recovery i.e. the old index must be kept intact until the
+ * new index is successfully written. The old-idx RB-tree is used for the
+ * in-the-gaps method of writing index nodes and is destroyed every commit.
+ */
+void destroy_old_idx(struct ubifs_info *c)
+{
+ struct rb_node *this = c->old_idx.rb_node;
+ struct ubifs_old_idx *old_idx;
+
+ while (this) {
+ if (this->rb_left) {
+ this = this->rb_left;
+ continue;
+ } else if (this->rb_right) {
+ this = this->rb_right;
+ continue;
+ }
+ old_idx = rb_entry(this, struct ubifs_old_idx, rb);
+ this = rb_parent(this);
+ if (this) {
+ if (this->rb_left == &old_idx->rb)
+ this->rb_left = NULL;
+ else
+ this->rb_right = NULL;
+ }
+ kfree(old_idx);
+ }
+ c->old_idx = RB_ROOT;
+}
+
+/**
+ * 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)
+ goto out;
+
+ 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) {
+ dbg_err("current fanout %d, branch count %d",
+ c->fanout, znode->child_cnt);
+ dbg_err("max levels %d, znode level %d",
+ UBIFS_MAX_LEVELS, znode->level);
+ 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) {
+ dbg_err("bad branch %d", i);
+ 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:
+ dbg_msg("bad key type at slot %d: %s", i,
+ DBGKEY(&zbr->key));
+ 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) {
+ dbg_err("bad target node (type %d) length (%d)",
+ type, zbr->len);
+ dbg_err("have to be %d", c->ranges[type].len);
+ goto out_dump;
+ }
+ } else if (zbr->len < c->ranges[type].min_len ||
+ zbr->len > c->ranges[type].max_len) {
+ dbg_err("bad target node (type %d) length (%d)",
+ type, zbr->len);
+ dbg_err("have to be in range of %d-%d",
+ c->ranges[type].min_len,
+ c->ranges[type].max_len);
+ 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) {
+ dbg_err("bad key order (keys %d and %d)", i, i + 1);
+ goto out_dump;
+ } else if (cmp == 0 && !is_hash_key(c, key1)) {
+ /* These can only be keys with colliding hash */
+ dbg_err("keys %d and %d are not hashed but equivalent",
+ i, i + 1);
+ goto out_dump;
+ }
+ }
+
+ kfree(idx);
+ return 0;
+
+out:
+ kfree(idx);
+ return err;
+
+out_dump:
+ ubifs_err("bad indexing node at LEB %d:%d", lnum, offs);
+ dbg_dump_node(c, idx);
+ kfree(idx);
+ return -EINVAL;
+}
+
+/**
+ * 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.
+ */
+static struct ubifs_znode *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);
+}
+
+/**
+ * copy_znode - copy a dirty znode.
+ * @c: UBIFS file-system description object
+ * @znode: znode to copy
+ *
+ * A dirty znode being committed may not be changed, so it is copied.
+ */
+static struct ubifs_znode *copy_znode(struct ubifs_info *c,
+ struct ubifs_znode *znode)
+{
+ struct ubifs_znode *zn;
+
+ zn = kmalloc(c->max_znode_sz, GFP_NOFS);
+ if (unlikely(!zn))
+ return ERR_PTR(-ENOMEM);
+
+ memcpy(zn, znode, c->max_znode_sz);
+ zn->cnext = NULL;
+ __set_bit(DIRTY_ZNODE, &zn->flags);
+ __clear_bit(COW_ZNODE, &zn->flags);
+
+ ubifs_assert(!test_bit(OBSOLETE_ZNODE, &znode->flags));
+ __set_bit(OBSOLETE_ZNODE, &znode->flags);
+
+ if (znode->level != 0) {
+ int i;
+ const int n = zn->child_cnt;
+
+ /* The children now have new parent */
+ for (i = 0; i < n; i++) {
+ struct ubifs_zbranch *zbr = &zn->zbranch[i];
+
+ if (zbr->znode)
+ zbr->znode->parent = zn;
+ }
+ }
+
+ atomic_long_inc(&c->dirty_zn_cnt);
+ return zn;
+}
+
+/**
+ * add_idx_dirt - add dirt due to a dirty znode.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number of index node
+ * @dirt: size of index node
+ *
+ * This function updates lprops dirty space and the new size of the index.
+ */
+static int add_idx_dirt(struct ubifs_info *c, int lnum, int dirt)
+{
+ c->calc_idx_sz -= ALIGN(dirt, 8);
+ return ubifs_add_dirt(c, lnum, dirt);
+}
+
+/**
+ * dirty_cow_znode - ensure a znode is not being committed.
+ * @c: UBIFS file-system description object
+ * @zbr: branch of znode to check
+ *
+ * Returns dirtied znode on success or negative error code on failure.
+ */
+static struct ubifs_znode *dirty_cow_znode(struct ubifs_info *c,
+ struct ubifs_zbranch *zbr)
+{
+ struct ubifs_znode *znode = zbr->znode;
+ struct ubifs_znode *zn;
+ int err;
+
+ if (!test_bit(COW_ZNODE, &znode->flags)) {
+ /* znode is not being committed */
+ if (!test_and_set_bit(DIRTY_ZNODE, &znode->flags)) {
+ atomic_long_inc(&c->dirty_zn_cnt);
+ atomic_long_dec(&c->clean_zn_cnt);
+ atomic_long_dec(&ubifs_clean_zn_cnt);
+ err = add_idx_dirt(c, zbr->lnum, zbr->len);
+ if (unlikely(err))
+ return ERR_PTR(err);
+ }
+ return znode;
+ }
+
+ zn = copy_znode(c, znode);
+ if (unlikely(IS_ERR(zn)))
+ return zn;
+
+ if (zbr->len) {
+ err = insert_old_idx(c, zbr->lnum, zbr->offs);
+ if (unlikely(err))
+ return ERR_PTR(err);
+ err = add_idx_dirt(c, zbr->lnum, zbr->len);
+ } else
+ err = 0;
+
+ zbr->znode = zn;
+ zbr->lnum = 0;
+ zbr->offs = 0;
+ zbr->len = 0;
+
+ if (unlikely(err))
+ return ERR_PTR(err);
+ return zn;
+}
+
+/**
+ * ubifs_validate_entry - validate directory or extended attribute entry node.
+ * @c: UBIFS file-system description object
+ * @dent: the node to validate
+ *
+ * This function validates directory or extended attribute entry node @dent.
+ * Returns zero if the node is all right and a %-EINVAL if not.
+ */
+int ubifs_validate_entry(struct ubifs_info *c,
+ const struct ubifs_dent_node *dent)
+{
+ int key_type = key_type_flash(c, dent->key);
+ int nlen = le16_to_cpu(dent->nlen);
+
+ if (le32_to_cpu(dent->ch.len) != nlen + UBIFS_DENT_NODE_SZ + 1 ||
+ dent->type >= UBIFS_ITYPES_CNT ||
+ nlen > UBIFS_MAX_NLEN || dent->name[nlen] != 0 ||
+ strnlen(dent->name, nlen) != nlen ||
+ le64_to_cpu(dent->inum) > MAX_INUM) {
+ ubifs_err("bad %s node", key_type == UBIFS_DENT_KEY ?
+ "directory entry" : "extended attribute entry");
+ return -EINVAL;
+ }
+
+ if (key_type != UBIFS_DENT_KEY && key_type != UBIFS_XENT_KEY) {
+ ubifs_err("bad key type %d", key_type);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * lnc_add - add a leaf node to the leaf node cache.
+ * @c: UBIFS file-system description object
+ * @zbr: zbranch of leaf node
+ * @node: leaf node
+ *
+ * Leaf nodes are non-index nodes directory entry nodes or data nodes. The
+ * purpose of the leaf node cache is to save re-reading the same leaf node over
+ * and over again. Most things are cached by VFS, however the file system must
+ * cache directory entries for readdir and for resolving hash collisions. The
+ * present implementation of the leaf node cache is extremely simple, and
+ * allows for error returns that are not used but that may be needed if a more
+ * complex implementation is created.
+ *
+ * Note, this function does not add the @node object to LNC directly, but
+ * allocates a copy of the object and adds the copy to LNC. The reason for this
+ * is that @node has been allocated outside of the TNC subsystem and will be
+ * used with @c->tnc_mutex unlock upon return from the TNC subsystem. But LNC
+ * may be changed at any time, e.g. freed by the shrinker.
+ */
+static int lnc_add(struct ubifs_info *c, struct ubifs_zbranch *zbr,
+ const void *node)
+{
+ int err;
+ void *lnc_node;
+ const struct ubifs_dent_node *dent = node;
+
+ ubifs_assert(!zbr->leaf);
+ ubifs_assert(zbr->len != 0);
+ ubifs_assert(is_hash_key(c, &zbr->key));
+
+ err = ubifs_validate_entry(c, dent);
+ if (err) {
+ dbg_dump_node(c, dent);
+ return err;
+ }
+
+ lnc_node = kmalloc(zbr->len, GFP_NOFS);
+ if (!lnc_node)
+ /* We don't have to have the cache, so no error */
+ return 0;
+
+ memcpy(lnc_node, node, zbr->len);
+ zbr->leaf = lnc_node;
+ return 0;
+}
+
+ /**
+ * lnc_add_directly - add a leaf node to the leaf-node-cache.
+ * @c: UBIFS file-system description object
+ * @zbr: zbranch of leaf node
+ * @node: leaf node
+ *
+ * This function is similar to 'lnc_add()', but it does not create a copy of
+ * @node but inserts @node to TNC directly.
+ */
+static int lnc_add_directly(struct ubifs_info *c, struct ubifs_zbranch *zbr,
+ void *node)
+{
+ int err;
+
+ ubifs_assert(!zbr->leaf);
+ ubifs_assert(zbr->len != 0);
+
+ err = ubifs_validate_entry(c, node);
+ if (err) {
+ dbg_dump_node(c, node);
+ return err;
+ }
+
+ zbr->leaf = node;
+ return 0;
+}
+
+/**
+ * lnc_free - remove a leaf node from the leaf node cache.
+ * @zbr: zbranch of leaf node
+ * @node: leaf node
+ */
+static void lnc_free(struct ubifs_zbranch *zbr)
+{
+ if (!zbr->leaf)
+ return;
+ kfree(zbr->leaf);
+ zbr->leaf = NULL;
+}
+
+/**
+ * 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.
+ */
+static int 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;
+
+ ubifs_assert(!zbr->leaf);
+
+ /*
+ * '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_tnc("key %s", DBGKEY(key));
+ return err;
+ }
+
+ /* Make sure the key of the read node is correct */
+ key_read(c, key, &key1);
+ if (memcmp(node + UBIFS_KEY_OFFSET, &key1, c->key_len)) {
+ ubifs_err("bad key in node at LEB %d:%d",
+ zbr->lnum, zbr->offs);
+ dbg_tnc("looked for key %s found node's key %s",
+ DBGKEY(key), DBGKEY1(&key1));
+ dbg_dump_node(c, node);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * tnc_read_node_nm - read a "hashed" leaf node.
+ * @c: UBIFS file-system description object
+ * @zbr: key and position of the node
+ * @node: node is returned here
+ *
+ * This function reads a "hashed" node defined by @zbr from the leaf node cache
+ * (in it is there) or from the hash media, in which case the node is also
+ * added to LNC. Returns zero in case of success or a negative negative error
+ * code in case of failure.
+ */
+static int tnc_read_node_nm(struct ubifs_info *c, struct ubifs_zbranch *zbr,
+ void *node)
+{
+ int err;
+
+ ubifs_assert(is_hash_key(c, &zbr->key));
+
+ if (zbr->leaf) {
+ /* Read from the leaf node cache */
+ ubifs_assert(zbr->len != 0);
+ memcpy(node, zbr->leaf, zbr->len);
+ return 0;
+ }
+
+ err = tnc_read_node(c, zbr, node);
+ if (err)
+ return err;
+
+ /* Add the node to the leaf node cache */
+ err = lnc_add(c, zbr, node);
+ return err;
+}
+
+/**
+ * try_read_node - read a node if it is a node.
+ * @c: UBIFS file-system description object
+ * @buf: buffer to read to
+ * @type: node type
+ * @len: node length (not aligned)
+ * @lnum: LEB number of node to read
+ * @offs: offset of node to read
+ *
+ * This function tries to read a node of known type and length, checks it and
+ * stores it in @buf. This function returns %1 if a node is present and %0 if
+ * a node is not present. A negative error code is returned for I/O errors.
+ * This function performs that same function as ubifs_read_node except that
+ * it does not require that there is actually a node present and instead
+ * the return code indicates if a node was read.
+ */
+static int try_read_node(const struct ubifs_info *c, void *buf, int type,
+ int len, int lnum, int offs)
+{
+ int err, node_len;
+ struct ubifs_ch *ch = buf;
+ uint32_t crc, node_crc;
+
+ dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
+
+ err = ubi_read(c->ubi, lnum, buf, offs, len);
+ if (err) {
+ ubifs_err("cannot read node type %d from LEB %d:%d, error %d",
+ type, lnum, offs, err);
+ return err;
+ }
+
+ if (le32_to_cpu(ch->magic) != UBIFS_NODE_MAGIC)
+ return 0;
+
+ if (ch->node_type != type)
+ return 0;
+
+ node_len = le32_to_cpu(ch->len);
+ if (node_len != len)
+ return 0;
+
+ crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
+ node_crc = le32_to_cpu(ch->crc);
+ if (crc != node_crc)
+ return 0;
+
+ return 1;
+}
+
+/**
+ * fallible_read_node - try to read a leaf node.
+ * @c: UBIFS file-system description object
+ * @key: key of node to read
+ * @zbr: position of node
+ * @node: node returned
+ *
+ * This function tries to read a node and returns %1 if the node is read, %0
+ * if the node is not present, and a negative error code in the case of error.
+ */
+static int fallible_read_node(struct ubifs_info *c, const union ubifs_key *key,
+ struct ubifs_zbranch *zbr, void *node)
+{
+ int ret;
+
+ dbg_tnc("LEB %d:%d, key %s", zbr->lnum, zbr->offs, DBGKEY(key));
+
+ ret = try_read_node(c, node, key_type(c, key), zbr->len, zbr->lnum,
+ zbr->offs);
+ if (ret == 1) {
+ union ubifs_key node_key;
+ struct ubifs_dent_node *dent = node;
+
+ /* All nodes have key in the same place */
+ key_read(c, &dent->key, &node_key);
+ if (keys_cmp(c, key, &node_key) != 0)
+ ret = 0;
+ }
+ if (ret == 0)
+ dbg_mnt("dangling branch LEB %d:%d len %d, key %s",
+ zbr->lnum, zbr->offs, zbr->len, DBGKEY(key));
+ return ret;
+}
+
+/**
+ * matches_name - determine if a directory or extended attribute entry matches
+ * a given name.
+ * @c: UBIFS file-system description object
+ * @zbr: zbranch of dent
+ * @nm: name to match
+ *
+ * This function checks if xentry/direntry referred by zbranch @zbr matches name
+ * @nm. Returns %NAME_MATCHES if it does, %NAME_LESS if the name referred by
+ * @zbr is less than @nm, and %NAME_GREATER if it is greater than @nm. In case
+ * of failure, a negative error code is returned.
+ */
+static int matches_name(struct ubifs_info *c, struct ubifs_zbranch *zbr,
+ const struct qstr *nm)
+{
+ struct ubifs_dent_node *dent;
+ int nlen, err;
+
+ /* If possible, match against the dent in the leaf node cache */
+ if (!zbr->leaf) {
+ dent = kmalloc(zbr->len, GFP_NOFS);
+ if (!dent)
+ return -ENOMEM;
+
+ err = tnc_read_node(c, zbr, dent);
+ if (err)
+ goto out_free;
+
+ /* Add the node to the leaf node cache */
+ err = lnc_add_directly(c, zbr, dent);
+ if (err)
+ goto out_free;
+ } else
+ dent = zbr->leaf;
+
+ nlen = le16_to_cpu(dent->nlen);
+ err = memcmp(dent->name, nm->name, min_t(int, nlen, nm->len));
+ if (err == 0) {
+ if (nlen == nm->len)
+ return NAME_MATCHES;
+ else if (nlen < nm->len)
+ return NAME_LESS;
+ else
+ return NAME_GREATER;
+ } else if (err < 0)
+ return NAME_LESS;
+ else
+ return NAME_GREATER;
+
+out_free:
+ kfree(dent);
+ return err;
+}
+
+/**
+ * get_znode - get a TNC znode that may not be loaded yet.
+ * @c: UBIFS file-system description object
+ * @znode: parent znode
+ * @n: znode branch slot number
+ *
+ * This function returns the znode or a negative error code.
+ */
+static struct ubifs_znode *get_znode(struct ubifs_info *c,
+ struct ubifs_znode *znode, int n)
+{
+ struct ubifs_zbranch *zbr;
+
+ zbr = &znode->zbranch[n];
+ if (zbr->znode)
+ znode = zbr->znode;
+ else
+ znode = load_znode(c, zbr, znode, n);
+ return znode;
+}
+
+/**
+ * tnc_next - find next TNC entry.
+ * @c: UBIFS file-system description object
+ * @zn: znode is passed and returned here
+ * @n: znode branch slot number is passed and returned here
+ *
+ * This function returns %0 if the next TNC entry is found, %-ENOENT if there is
+ * no next entry, or a negative error code otherwise.
+ */
+static int tnc_next(struct ubifs_info *c, struct ubifs_znode **zn, int *n)
+{
+ struct ubifs_znode *znode = *zn;
+ int nn = *n;
+
+ nn += 1;
+ if (nn < znode->child_cnt) {
+ *n = nn;
+ return 0;
+ }
+ while (1) {
+ struct ubifs_znode *zp;
+
+ zp = znode->parent;
+ if (!zp)
+ return -ENOENT;
+ nn = znode->iip + 1;
+ znode = zp;
+ if (nn < znode->child_cnt) {
+ znode = get_znode(c, znode, nn);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ while (znode->level != 0) {
+ znode = get_znode(c, znode, 0);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ }
+ nn = 0;
+ break;
+ }
+ }
+ *zn = znode;
+ *n = nn;
+ return 0;
+}
+
+/**
+ * tnc_prev - find previous TNC entry.
+ * @c: UBIFS file-system description object
+ * @zn: znode is returned here
+ * @n: znode branch slot number is passed and returned here
+ *
+ * This function returns %0 if the previous TNC entry is found, %-ENOENT if
+ * there is no next entry, or a negative error code otherwise.
+ */
+static int tnc_prev(struct ubifs_info *c, struct ubifs_znode **zn, int *n)
+{
+ struct ubifs_znode *znode = *zn;
+ int nn = *n;
+
+ if (nn > 0) {
+ *n = nn - 1;
+ return 0;
+ }
+ while (1) {
+ struct ubifs_znode *zp;
+
+ zp = znode->parent;
+ if (!zp)
+ return -ENOENT;
+ nn = znode->iip - 1;
+ znode = zp;
+ if (nn >= 0) {
+ znode = get_znode(c, znode, nn);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ while (znode->level != 0) {
+ nn = znode->child_cnt - 1;
+ znode = get_znode(c, znode, nn);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ }
+ nn = znode->child_cnt - 1;
+ break;
+ }
+ }
+ *zn = znode;
+ *n = nn;
+ return 0;
+}
+
+/**
+ * resolve_collision - resolve a collision.
+ * @c: UBIFS file-system description object
+ * @key: key of a directory or extended attribute entry
+ * @zn: znode is returned here
+ * @n: zbranch number is passed and returned here
+ * @nm: name of the entry
+ *
+ * This function is called for "hashed" keys to make sure that the found key
+ * really corresponds to the looked up node (directory or extended attribute
+ * entry). It returns %1 and sets @zn and @n if the collision is resolved.
+ * %0 is returned if @nm is not found and @zn and @n are set to the previous
+ * entry, i.e. to the entry after which @nm could follow if it were in TNC.
+ * This means that @n may be set to %-1 if the leftmost key in @zn is the
+ * previous one. A negative error code is returned on failures.
+ */
+static int resolve_collision(struct ubifs_info *c, const union ubifs_key *key,
+ struct ubifs_znode **zn, int *n,
+ const struct qstr *nm)
+{
+ int err;
+
+ err = matches_name(c, &(*zn)->zbranch[*n], nm);
+ if (unlikely(err < 0))
+ return err;
+ if (err == NAME_MATCHES)
+ return 1;
+
+ if (err == NAME_GREATER) {
+ /* Look left */
+ while (1) {
+ err = tnc_prev(c, zn, n);
+ if (err == -ENOENT) {
+ ubifs_assert(*n == 0);
+ *n = -1;
+ return 0;
+ }
+ if (err < 0)
+ return err;
+ if (keys_cmp(c, &(*zn)->zbranch[*n].key, key)) {
+ /*
+ * We have found the branch after which we would
+ * like to insert, but inserting in this znode
+ * may still be wrong. Consider the following 3
+ * znodes, in the case where we are resolving a
+ * collision with Key2.
+ *
+ * znode zp
+ * ----------------------
+ * level 1 | Key0 | Key1 |
+ * -----------------------
+ * | |
+ * znode za | | znode zb
+ * ------------ ------------
+ * level 0 | Key0 | | Key2 |
+ * ------------ ------------
+ *
+ * The lookup finds Key2 in znode zb. Lets say
+ * there is no match and the name is greater so
+ * we look left. When we find Key0, we end up
+ * here. If we return now, we will insert into
+ * znode za at slot n = 1. But that is invalid
+ * according to the parent's keys. Key2 must
+ * be inserted into znode zb.
+ *
+ * Note, this problem is not relevant for the
+ * case when we go right, because
+ * 'tnc_insert()' would correct the parent key.
+ */
+ if (*n == (*zn)->child_cnt - 1) {
+ err = tnc_next(c, zn, n);
+ if (err) {
+ /* Should be impossible */
+ ubifs_assert(0);
+ if (err == -ENOENT)
+ err = -EINVAL;
+ return err;
+ }
+ ubifs_assert(*n == 0);
+ *n = -1;
+ }
+ return 0;
+ }
+ err = matches_name(c, &(*zn)->zbranch[*n], nm);
+ if (err < 0)
+ return err;
+ if (err == NAME_LESS)
+ return 0;
+ if (err == NAME_MATCHES)
+ return 1;
+ ubifs_assert(err == NAME_GREATER);
+ }
+ } else {
+ int nn = *n;
+ struct ubifs_znode *znode = *zn;
+
+ /* Look right */
+ while (1) {
+ err = tnc_next(c, &znode, &nn);
+ if (err == -ENOENT)
+ return 0;
+ if (err < 0)
+ return err;
+ if (keys_cmp(c, &znode->zbranch[nn].key, key))
+ return 0;
+ err = matches_name(c, &znode->zbranch[nn], nm);
+ if (err < 0)
+ return err;
+ if (err == NAME_GREATER)
+ return 0;
+ *zn = znode;
+ *n = nn;
+ if (err == NAME_MATCHES)
+ return 1;
+ ubifs_assert(err == NAME_LESS);
+ }
+ }
+}
+
+/**
+ * fallible_matches_name - determine if a dent matches a given name.
+ * @c: UBIFS file-system description object
+ * @zbr: zbranch of dent
+ * @nm: name to match
+ *
+ * This is a "fallible" version of 'matches_name()' function which does not
+ * panic if the direntry/xentry referred by @zbr does not exist on the media.
+ *
+ * This function checks if xentry/direntry referred by zbranch @zbr matches name
+ * @nm. Returns %NAME_MATCHES it does, %NAME_LESS if the name referred by @zbr
+ * is less than @nm, %NAME_GREATER if it is greater than @nm, and @NOT_ON_MEDIA
+ * if xentry/direntry referred by @zbr does not exist on the media. A negative
+ * error code is returned in case of failure.
+ */
+static int fallible_matches_name(struct ubifs_info *c,
+ struct ubifs_zbranch *zbr,
+ const struct qstr *nm)
+{
+ struct ubifs_dent_node *dent;
+ int nlen, err;
+
+ /* If possible, match against the dent in the leaf node cache */
+ if (!zbr->leaf) {
+ dent = kmalloc(zbr->len, GFP_NOFS);
+ if (!dent)
+ return -ENOMEM;
+
+ err = fallible_read_node(c, &zbr->key, zbr, dent);
+ if (err < 0)
+ goto out_free;
+ if (err == 0) {
+ /* The node was not present */
+ err = NOT_ON_MEDIA;
+ goto out_free;
+ }
+ ubifs_assert(err == 1);
+
+ err = lnc_add_directly(c, zbr, dent);
+ if (err)
+ goto out_free;
+ } else
+ dent = zbr->leaf;
+
+ nlen = le16_to_cpu(dent->nlen);
+ err = memcmp(dent->name, nm->name, min_t(int, nlen, nm->len));
+ if (err == 0) {
+ if (nlen == nm->len)
+ return NAME_MATCHES;
+ else if (nlen < nm->len)
+ return NAME_LESS;
+ else
+ return NAME_GREATER;
+ } else if (err < 0)
+ return NAME_LESS;
+ else
+ return NAME_GREATER;
+
+out_free:
+ kfree(dent);
+ return err;
+}
+
+/**
+ * fallible_resolve_collision - resolve a collision even if nodes are missing.
+ * @c: UBIFS file-system description object
+ * @key: key
+ * @zn: znode is returned here
+ * @n: branch number is passed and returned here
+ * @nm: name of directory entry
+ * @adding: indicates caller is adding a key to the TNC
+ *
+ * This is a "fallible" version of the 'resolve_collision()' function which
+ * does not panic if one of the nodes referred to by TNC does not exist on the
+ * media. This may happen when replaying the journal if a deleted node was
+ * Garbage-collected and the commit was not done. A branch that refers to a node
+ * that is not present is called a dangling branch. The following are the return
+ * codes for this function:
+ * o if @nm was found, %1 is returned and @zn and @n are set to the found
+ * branch;
+ * o if we are @adding and @nm was not found, %0 is returned;
+ * o if we are not @adding and @nm was not found, but a dangling branch was
+ * found, then %1 is returned and @zn and @n are set to the dangling branch;
+ * o a negative error code is returned in case of failure.
+ */
+static int fallible_resolve_collision(struct ubifs_info *c,
+ const union ubifs_key *key,
+ struct ubifs_znode **zn, int *n,
+ const struct qstr *nm, int adding)
+{
+ struct ubifs_znode *o_znode = NULL, *znode = *zn;
+ int uninitialized_var(o_n), err, cmp, unsure = 0, nn = *n;
+
+ cmp = fallible_matches_name(c, &znode->zbranch[nn], nm);
+ if (unlikely(cmp < 0))
+ return cmp;
+ if (cmp == NAME_MATCHES)
+ return 1;
+ if (cmp == NOT_ON_MEDIA) {
+ o_znode = znode;
+ o_n = nn;
+ /*
+ * We are unlucky and hit a dangling branch straight away.
+ * Now we do not really know where to go to find the needed
+ * branch - to the left or to the right. Well, let's try left.
+ */
+ unsure = 1;
+ } else if (!adding)
+ unsure = 1; /* Remove a dangling branch wherever it is */
+
+ if (cmp == NAME_GREATER || unsure) {
+ /* Look left */
+ while (1) {
+ err = tnc_prev(c, zn, n);
+ if (err == -ENOENT) {
+ ubifs_assert(*n == 0);
+ *n = -1;
+ break;
+ }
+ if (err < 0)
+ return err;
+ if (keys_cmp(c, &(*zn)->zbranch[*n].key, key)) {
+ /* See comments in 'resolve_collision()' */
+ if (*n == (*zn)->child_cnt - 1) {
+ err = tnc_next(c, zn, n);
+ if (err) {
+ /* Should be impossible */
+ ubifs_assert(0);
+ if (err == -ENOENT)
+ err = -EINVAL;
+ return err;
+ }
+ ubifs_assert(*n == 0);
+ *n = -1;
+ }
+ break;
+ }
+ err = fallible_matches_name(c, &(*zn)->zbranch[*n], nm);
+ if (err < 0)
+ return err;
+ if (err == NAME_MATCHES)
+ return 1;
+ if (err == NOT_ON_MEDIA) {
+ o_znode = *zn;
+ o_n = *n;
+ continue;
+ }
+ if (!adding)
+ continue;
+ if (err == NAME_LESS)
+ break;
+ else
+ unsure = 0;
+ }
+ }
+
+ if (cmp == NAME_LESS || unsure) {
+ /* Look right */
+ *zn = znode;
+ *n = nn;
+ while (1) {
+ err = tnc_next(c, &znode, &nn);
+ if (err == -ENOENT)
+ break;
+ if (err < 0)
+ return err;
+ if (keys_cmp(c, &znode->zbranch[nn].key, key))
+ break;
+ err = fallible_matches_name(c, &znode->zbranch[nn], nm);
+ if (err < 0)
+ return err;
+ if (err == NAME_GREATER)
+ break;
+ *zn = znode;
+ *n = nn;
+ if (err == NAME_MATCHES)
+ return 1;
+ if (err == NOT_ON_MEDIA) {
+ o_znode = znode;
+ o_n = nn;
+ }
+ }
+ }
+
+ /* Never match a dangling branch when adding */
+ if (adding || !o_znode)
+ return 0;
+
+ dbg_mnt("dangling match LEB %d:%d len %d %s",
+ o_znode->zbranch[o_n].lnum, o_znode->zbranch[o_n].offs,
+ o_znode->zbranch[o_n].len, DBGKEY(key));
+ *zn = o_znode;
+ *n = o_n;
+ return 1;
+}
+
+/**
+ * matches_position - determine if a zbranch matches a given position.
+ * @zbr: zbranch of dent
+ * @lnum: LEB number of dent to match
+ * @offs: offset of dent to match
+ *
+ * This function returns %1 if @lnum:@offs matches, and %0 otherwise.
+ */
+static int matches_position(struct ubifs_zbranch *zbr, int lnum, int offs)
+{
+ if (zbr->lnum == lnum && zbr->offs == offs)
+ return 1;
+ else
+ return 0;
+}
+
+/**
+ * resolve_collision_directly - resolve a collision directly.
+ * @c: UBIFS file-system description object
+ * @key: key of directory entry
+ * @zn: znode is passed and returned here
+ * @n: zbranch number is passed and returned here
+ * @lnum: LEB number of dent node to match
+ * @offs: offset of dent node to match
+ *
+ * This function is used for "hashed" keys to make sure the found directory or
+ * extended attribute entry node is what was looked for. It is used when the
+ * flash address of the right node is known (@lnum:@offs) which makes it much
+ * easier to resolve collisions (no need to read entries and match full
+ * names). This function returns %1 and sets @zn and @n if the collision is
+ * resolved, %0 if @lnum:@offs is not found and @zn and @n are set to the
+ * previous directory entry. Otherwise a negative error code is returned.
+ */
+static int resolve_collision_directly(struct ubifs_info *c,
+ const union ubifs_key *key,
+ struct ubifs_znode **zn, int *n,
+ int lnum, int offs)
+{
+ struct ubifs_znode *znode;
+ int nn, err;
+
+ znode = *zn;
+ nn = *n;
+ if (matches_position(&znode->zbranch[nn], lnum, offs))
+ return 1;
+
+ /* Look left */
+ while (1) {
+ err = tnc_prev(c, &znode, &nn);
+ if (err == -ENOENT)
+ break;
+ if (err < 0)
+ return err;
+ if (keys_cmp(c, &znode->zbranch[nn].key, key))
+ break;
+ if (matches_position(&znode->zbranch[nn], lnum, offs)) {
+ *zn = znode;
+ *n = nn;
+ return 1;
+ }
+ }
+
+ /* Look right */
+ znode = *zn;
+ nn = *n;
+ while (1) {
+ err = tnc_next(c, &znode, &nn);
+ if (err == -ENOENT)
+ return 0;
+ if (err < 0)
+ return err;
+ if (keys_cmp(c, &znode->zbranch[nn].key, key))
+ return 0;
+ *zn = znode;
+ *n = nn;
+ if (matches_position(&znode->zbranch[nn], lnum, offs))
+ return 1;
+ }
+}
+
+/**
+ * dirty_cow_bottom_up - dirty a znode and its ancestors.
+ * @c: UBIFS file-system description object
+ * @znode: znode to dirty
+ *
+ * If we do not have a unique key that resides in a znode, then we cannot
+ * dirty that znode from the top down (i.e. by using lookup_level0_dirty)
+ * This function records the path back to the last dirty ancestor, and then
+ * dirties the znodes on that path.
+ */
+static struct ubifs_znode *dirty_cow_bottom_up(struct ubifs_info *c,
+ struct ubifs_znode *znode)
+{
+ struct ubifs_znode *zp;
+ int *path = c->bottom_up_buf, p = 0;
+
+ ubifs_assert(c->zroot.znode);
+ ubifs_assert(znode);
+ if (c->zroot.znode->level > BOTTOM_UP_HEIGHT) {
+ kfree(c->bottom_up_buf);
+ c->bottom_up_buf = kmalloc(c->zroot.znode->level * sizeof(int),
+ GFP_NOFS);
+ if (!c->bottom_up_buf)
+ return ERR_PTR(-ENOMEM);
+ path = c->bottom_up_buf;
+ }
+ if (c->zroot.znode->level) {
+ /* Go up until parent is dirty */
+ while (1) {
+ int n;
+
+ zp = znode->parent;
+ if (!zp)
+ break;
+ n = znode->iip;
+ ubifs_assert(p < c->zroot.znode->level);
+ path[p++] = n;
+ if (!zp->cnext && ubifs_zn_dirty(znode))
+ break;
+ znode = zp;
+ }
+ }
+
+ /* Come back down, dirtying as we go */
+ while (1) {
+ struct ubifs_zbranch *zbr;
+
+ zp = znode->parent;
+ if (zp) {
+ ubifs_assert(path[p - 1] >= 0);
+ ubifs_assert(path[p - 1] < zp->child_cnt);
+ zbr = &zp->zbranch[path[--p]];
+ znode = dirty_cow_znode(c, zbr);
+ } else {
+ ubifs_assert(znode == c->zroot.znode);
+ znode = dirty_cow_znode(c, &c->zroot);
+ }
+ if (unlikely(IS_ERR(znode)) || !p)
+ break;
+ ubifs_assert(path[p - 1] >= 0);
+ ubifs_assert(path[p - 1] < znode->child_cnt);
+ znode = znode->zbranch[path[p - 1]].znode;
+ }
+
+ return znode;
+}
+
+/**
+ * lookup_level0 - search for zero-level znode.
+ * @c: UBIFS file-system description object
+ * @key: key to lookup
+ * @zn: znode is returned here
+ * @n: znode branch slot number is returned here
+ *
+ * This function looks up the TNC tree and search for zero-level znode which
+ * refers key @key. The found zero-level znode is returned in @zn. There are 3
+ * cases:
+ * o exact match, i.e. the found zero-level znode contains key @key, then %1
+ * is returned and slot number of the matched branch is stored in @n;
+ * o not exact match, which means that zero-level znode does not contain
+ * @key, then %0 is returned and slot number of the closed branch is stored
+ * in @n;
+ * o @key is so small that it is even less than the lowest key of the
+ * leftmost zero-level node, then %0 is returned and %0 is stored in @n.
+ *
+ * Note, when the TNC tree is traversed, some znodes may be absent, then this
+ * function reads corresponding indexing nodes and inserts them to TNC. In
+ * case of failure, a negative error code is returned.
+ */
+static int lookup_level0(struct ubifs_info *c, const union ubifs_key *key,
+ struct ubifs_znode **zn, int *n)
+{
+ int err, exact;
+ struct ubifs_znode *znode;
+ unsigned long time = get_seconds();
+
+ dbg_tnc("search key %s", DBGKEY(key));
+
+ znode = c->zroot.znode;
+ if (unlikely(!znode)) {
+ znode = load_znode(c, &c->zroot, NULL, 0);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ }
+
+ znode->time = time;
+
+ while (1) {
+ struct ubifs_zbranch *zbr;
+
+ exact = ubifs_search_zbranch(c, znode, key, n);
+
+ if (znode->level == 0)
+ break;
+
+ if (*n < 0)
+ *n = 0;
+ zbr = &znode->zbranch[*n];
+
+ if (zbr->znode) {
+ znode->time = time;
+ znode = zbr->znode;
+ continue;
+ }
+
+ /* znode is not in TNC cache, load it from the media */
+ znode = load_znode(c, zbr, znode, *n);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ }
+
+ *zn = znode;
+ if (exact || !is_hash_key(c, key) || *n != -1) {
+ dbg_tnc("found %d, lvl %d, n %d", exact, znode->level, *n);
+ return exact;
+ }
+
+ /*
+ * Here is a tricky place. We have not found the key and this is a
+ * "hashed" key, which may collide. The rest of the code deals with
+ * situations like this:
+ *
+ * | 3 | 5 |
+ * / \
+ * | 3 | 5 | | 6 | 7 | (x)
+ *
+ * Or more a complex example:
+ *
+ * | 1 | 5 |
+ * / \
+ * | 1 | 3 | | 5 | 8 |
+ * \ /
+ * | 5 | 5 | | 6 | 7 | (x)
+ *
+ * In the examples, if we are looking for key "5", we may reach nodes
+ * marked with "(x)". In this case what we have do is to look at the
+ * left and see if there is "5" key there. If there is, we have to
+ * return it.
+ *
+ * Note, this whole situation is possible because we allow to have
+ * elements which are equivalent to the next key in the parent in the
+ * children of current znode. For example, this happens if we split a
+ * znode like this: | 3 | 5 | 5 | 6 | 7 |, which results in something
+ * like this:
+ * | 3 | 5 |
+ * / \
+ * | 3 | 5 | | 5 | 6 | 7 |
+ * ^
+ * And this becomes what is at the first "picture" after key "5" marked
+ * with "^" is removed. What could be done is we could prohibit
+ * splitting in the middle of the colliding sequence. Also, when
+ * removing the leftmost key, we would have to correct the key of the
+ * parent node, which would introduce additional complications. Namely,
+ * if we changed the the leftmost key of the parent znode, the garbage
+ * collector would be unable to find it (GC is doing this when GC'ing
+ * indexing LEBs). Although we already have an additional RB-tree where
+ * we save such changed znodes (see 'ins_clr_old_idx_znode()') until
+ * after the commit. But anyway, this does not look easy to implement
+ * so we did not try this.
+ */
+ err = tnc_prev(c, &znode, n);
+ if (err == -ENOENT) {
+ dbg_tnc("found 0, lvl %d, n -1", znode->level);
+ *n = -1;
+ return 0;
+ }
+ if (unlikely(err < 0))
+ return err;
+ if (keys_cmp(c, key, &znode->zbranch[*n].key)) {
+ dbg_tnc("found 0, lvl %d, n -1", znode->level);
+ *n = -1;
+ return 0;
+ }
+
+ dbg_tnc("found 1, lvl %d, n %d", znode->level, *n);
+ *zn = znode;
+ return 1;
+}
+
+/**
+ * lookup_level0_dirty - search for zero-level znode dirtying.
+ * @c: UBIFS file-system description object
+ * @key: key to lookup
+ * @zn: znode is returned here
+ * @n: znode branch slot number is returned here
+ *
+ * This function looks up the TNC tree and search for zero-level znode which
+ * refers key @key. The found zero-level znode is returned in @zn. There are 3
+ * cases:
+ * o exact match, i.e. the found zero-level znode contains key @key, then %1
+ * is returned and slot number of the matched branch is stored in @n;
+ * o not exact match, which means that zero-level znode does not contain @key
+ * then %0 is returned and slot number of the closed branch is stored in
+ * @n;
+ * o @key is so small that it is even less than the lowest key of the
+ * leftmost zero-level node, then %0 is returned and %-1 is stored in @n.
+ *
+ * Additionally all znodes in the path from the root to the located zero-level
+ * znode are marked as dirty.
+ *
+ * Note, when the TNC tree is traversed, some znodes may be absent, then this
+ * function reads corresponding indexing nodes and inserts them to TNC. In
+ * case of failure, a negative error code is returned.
+ */
+static int lookup_level0_dirty(struct ubifs_info *c, const union ubifs_key *key,
+ struct ubifs_znode **zn, int *n)
+{
+ int err, exact;
+ struct ubifs_znode *znode;
+ unsigned long time = get_seconds();
+
+ dbg_tnc("search and dirty key %s", DBGKEY(key));
+
+ znode = c->zroot.znode;
+ if (unlikely(!znode)) {
+ znode = load_znode(c, &c->zroot, NULL, 0);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ }
+
+ znode = dirty_cow_znode(c, &c->zroot);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+
+ znode->time = time;
+
+ while (1) {
+ struct ubifs_zbranch *zbr;
+
+ exact = ubifs_search_zbranch(c, znode, key, n);
+
+ if (znode->level == 0)
+ break;
+
+ if (*n < 0)
+ *n = 0;
+ zbr = &znode->zbranch[*n];
+
+ if (zbr->znode) {
+ znode->time = time;
+ znode = dirty_cow_znode(c, zbr);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ continue;
+ }
+
+ /* znode is not in TNC cache, load it from the media */
+ znode = load_znode(c, zbr, znode, *n);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ znode = dirty_cow_znode(c, zbr);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ }
+
+ *zn = znode;
+ if (exact || !is_hash_key(c, key) || *n != -1) {
+ dbg_tnc("found %d, lvl %d, n %d", exact, znode->level, *n);
+ return exact;
+ }
+
+ /*
+ * See huge comment at 'lookup_level0_dirty()' what is the rest of the
+ * code.
+ */
+ err = tnc_prev(c, &znode, n);
+ if (err == -ENOENT) {
+ *n = -1;
+ dbg_tnc("found 0, lvl %d, n -1", znode->level);
+ return 0;
+ }
+ if (unlikely(err < 0))
+ return err;
+ if (keys_cmp(c, key, &znode->zbranch[*n].key)) {
+ *n = -1;
+ dbg_tnc("found 0, lvl %d, n -1", znode->level);
+ return 0;
+ }
+
+ if (znode->cnext || !ubifs_zn_dirty(znode)) {
+ znode = dirty_cow_bottom_up(c, znode);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ }
+
+ dbg_tnc("found 1, lvl %d, n %d", znode->level, *n);
+ *zn = znode;
+ return 1;
+}
+
+/**
+ * ubifs_tnc_lookup - look up a file-system node.
+ * @c: UBIFS file-system description object
+ * @key: node key to lookup
+ * @node: the node is returned here
+ *
+ * This function look up and reads node with key @key. The caller has to make
+ * sure the @node buffer is large enough to fit the node. Returns zero in case
+ * of success, %-ENOENT if the node was not found, and a negative error code in
+ * case of failure.
+ */
+int ubifs_tnc_lookup(struct ubifs_info *c, const union ubifs_key *key,
+ void *node)
+{
+ int found, n, err;
+ struct ubifs_znode *znode;
+ struct ubifs_zbranch zbr, *zt;
+
+ mutex_lock(&c->tnc_mutex);
+ found = lookup_level0(c, key, &znode, &n);
+ if (!found) {
+ err = -ENOENT;
+ goto out;
+ } else if (found < 0) {
+ err = found;
+ goto out;
+ }
+ zt = &znode->zbranch[n];
+ if (is_hash_key(c, key)) {
+ /*
+ * In this case the leaf node cache gets used, so we pass the
+ * address of the zbranch and keep the mutex locked
+ */
+ err = tnc_read_node_nm(c, zt, node);
+ goto out;
+ }
+ zbr = znode->zbranch[n];
+ mutex_unlock(&c->tnc_mutex);
+
+ err = tnc_read_node(c, &zbr, node);
+ return err;
+
+out:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * ubifs_tnc_locate - look up a file-system node and return it and its location.
+ * @c: UBIFS file-system description object
+ * @key: node key to lookup
+ * @node: the node is returned here
+ * @lnum: LEB number is returned here
+ * @offs: offset is returned here
+ *
+ * This function is the same as 'ubifs_tnc_lookup()' but it returns the node
+ * location also. See 'ubifs_tnc_lookup()'.
+ */
+int ubifs_tnc_locate(struct ubifs_info *c, const union ubifs_key *key,
+ void *node, int *lnum, int *offs)
+{
+ int found, n, err;
+ struct ubifs_znode *znode;
+ struct ubifs_zbranch zbr, *zt;
+
+ mutex_lock(&c->tnc_mutex);
+ found = lookup_level0(c, key, &znode, &n);
+ if (!found) {
+ err = -ENOENT;
+ goto out;
+ } else if (found < 0) {
+ err = found;
+ goto out;
+ }
+ zt = &znode->zbranch[n];
+ if (is_hash_key(c, key)) {
+ /*
+ * In this case the leaf node cache gets used, so we pass the
+ * address of the zbranch and keep the mutex locked
+ */
+ *lnum = zt->lnum;
+ *offs = zt->offs;
+ err = tnc_read_node_nm(c, zt, node);
+ goto out;
+ }
+ zbr = znode->zbranch[n];
+ mutex_unlock(&c->tnc_mutex);
+
+ *lnum = zbr.lnum;
+ *offs = zbr.offs;
+
+ err = tnc_read_node(c, &zbr, node);
+ return err;
+
+out:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * do_lookup_nm- look up a "hashed" node.
+ * directory entry file-system node.
+ * @c: UBIFS file-system description object
+ * @key: node key to lookup
+ * @node: the node is returned here
+ * @nm: node name
+ *
+ * This function look up and reads a node which contains name hash in the key.
+ * Since the hash may have collisions, there may be many nodes with the same
+ * key, so we have to sequentially look to all of them until the needed one is
+ * found. This function returns zero in case of success, %-ENOENT if the node
+ * was not found, and a negative error code in case of failure.
+ */
+static int do_lookup_nm(struct ubifs_info *c, const union ubifs_key *key,
+ void *node, const struct qstr *nm)
+{
+ int found, n, err;
+ struct ubifs_znode *znode;
+ struct ubifs_zbranch zbr;
+
+ dbg_tnc("name '%.*s' key %s", nm->len, nm->name, DBGKEY(key));
+ mutex_lock(&c->tnc_mutex);
+ found = lookup_level0(c, key, &znode, &n);
+ if (!found) {
+ err = -ENOENT;
+ goto out_unlock;
+ } else if (found < 0) {
+ err = found;
+ goto out_unlock;
+ }
+
+ ubifs_assert(n >= 0);
+
+ err = resolve_collision(c, key, &znode, &n, nm);
+ dbg_tnc("rc returned %d, znode %p, n %d", err, znode, n);
+ if (unlikely(err < 0))
+ goto out_unlock;
+ if (err == 0) {
+ err = -ENOENT;
+ goto out_unlock;
+ }
+
+ zbr = znode->zbranch[n];
+ mutex_unlock(&c->tnc_mutex);
+
+ err = tnc_read_node_nm(c, &zbr, node);
+ return err;
+
+out_unlock:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * ubifs_tnc_lookup_nm- look up a "hashed" node.
+ * directory entry file-system node.
+ * @c: UBIFS file-system description object
+ * @key: node key to lookup
+ * @node: the node is returned here
+ * @nm: node name
+ *
+ * This function look up and reads a node which contains name hash in the key.
+ * Since the hash may have collisions, there may be many nodes with the same
+ * key, so we have to sequentially look to all of them until the needed one is
+ * found. This function returns zero in case of success, %-ENOENT if the node
+ * was not found, and a negative error code in case of failure.
+ */
+int ubifs_tnc_lookup_nm(struct ubifs_info *c, const union ubifs_key *key,
+ void *node, const struct qstr *nm)
+{
+ int err, len;
+ const struct ubifs_dent_node *dent = node;
+
+ /*
+ * We assume that in most of the cases there are no name collisions and
+ * 'ubifs_tnc_lookup()' returns us the right direntry.
+ */
+ err = ubifs_tnc_lookup(c, key, node);
+ if (err)
+ return err;
+
+ len = le16_to_cpu(dent->nlen);
+ if (nm->len == len && !memcmp(dent->name, nm->name, len))
+ return 0;
+
+ /*
+ * Unluckily, there are hash collisions and we have to iterate over
+ * them look at each direntry with colliding name hash sequentially.
+ */
+ return do_lookup_nm(c, key, node, nm);
+}
+
+/**
+ * correct_parent_keys - correct parent znodes' keys.
+ * @c: UBIFS file-system description object
+ * @znode: znode to correct parent znodes for
+ *
+ * This is a helper function for 'tnc_insert()'. When the key of the leftmost
+ * zbranch changes, keys of parent znodes have to be corrected. This helper
+ * function is called in such situations and corrects the keys if needed.
+ */
+static void correct_parent_keys(const struct ubifs_info *c,
+ struct ubifs_znode *znode)
+{
+ union ubifs_key *key, *key1;
+
+ ubifs_assert(znode->parent);
+ ubifs_assert(znode->iip == 0);
+
+ key = &znode->zbranch[0].key;
+ key1 = &znode->parent->zbranch[0].key;
+
+ while (keys_cmp(c, key, key1) < 0) {
+ key_copy(c, key, key1);
+ znode = znode->parent;
+ if (!znode->parent || znode->iip)
+ break;
+ key1 = &znode->parent->zbranch[0].key;
+ }
+}
+
+/**
+ * insert_zbranch - insert a zbranch into a znode.
+ * @znode: znode into which to insert
+ * @zbr: zbranch to insert
+ * @n: slot number to insert to
+ *
+ * This is a helper function for 'tnc_insert()'. UBIFS does not allow "gaps" in
+ * znode's array of zbranches and keeps zbranches consolidated, so when a new
+ * zbranch has to be inserted to the @znode->zbranches[]' array at the @n-th
+ * slot, zbranches starting from @n have to be moved right.
+ */
+static void insert_zbranch(struct ubifs_znode *znode,
+ const struct ubifs_zbranch *zbr, int n)
+{
+ int i;
+
+ ubifs_assert(ubifs_zn_dirty(znode));
+
+ if (znode->level) {
+ for (i = znode->child_cnt; i > n; i--) {
+ znode->zbranch[i] = znode->zbranch[i - 1];
+ if (znode->zbranch[i].znode)
+ znode->zbranch[i].znode->iip = i;
+ }
+ if (zbr->znode)
+ zbr->znode->iip = n;
+ } else
+ for (i = znode->child_cnt; i > n; i--)
+ znode->zbranch[i] = znode->zbranch[i - 1];
+
+ znode->zbranch[n] = *zbr;
+ znode->child_cnt += 1;
+
+ /*
+ * After inserting at slot zero, the lower bound of the key range of
+ * this znode may have changed. If this znode is subsequently split
+ * then the upper bound of the key range may change, and furthermore
+ * it could change to be lower than the original lower bound. If that
+ * happens, then it will no longer be possible to find this znode in the
+ * TNC using the key from the index node on flash. That is bad because
+ * if it is not found, we will assume it is obsolete and may overwrite
+ * it. Then if there is an unclean unmount, we will start using the
+ * old index which will be broken.
+ *
+ * So we first mark znodes that have insertions at slot zero, and then
+ * if they are split we add their lnum/offs to the old_idx tree.
+ */
+ if (n == 0)
+ znode->alt = 1;
+}
+
+/**
+ * tnc_insert - insert a node into TNC.
+ * @c: UBIFS file-system description object
+ * @znode: znode to insert into
+ * @zbr: branch to insert
+ * @n: slot number to insert new zbranch to
+ *
+ * This function inserts a new node described by @zbr into znode @znode. If
+ * znode does not have a free slot for new zbranch, it is split. Parent znodes
+ * are splat as well if needed. Returns zero in case of success or a negative
+ * error code in case of failure.
+ */
+static int tnc_insert(struct ubifs_info *c, struct ubifs_znode *znode,
+ struct ubifs_zbranch *zbr, int n)
+{
+ struct ubifs_znode *zn, *zi, *zp;
+ int i, keep, move, appending = 0;
+ union ubifs_key *key = &zbr->key;
+
+ ubifs_assert(n >= 0 && n <= c->fanout);
+
+ /* Implement naive insert for now */
+again:
+ zp = znode->parent;
+ if (znode->child_cnt < c->fanout) {
+ ubifs_assert(n != c->fanout);
+ dbg_tnc("inserted at %d level %d, key %s", n, znode->level,
+ DBGKEY(key));
+
+ insert_zbranch(znode, zbr, n);
+
+ /* Ensure parent's key is correct */
+ if (n == 0 && zp && znode->iip == 0)
+ correct_parent_keys(c, znode);
+
+ return 0;
+ }
+
+ /*
+ * Unfortunately, @znode does not have more empty slots and we have to
+ * split it.
+ */
+ dbg_tnc("splitting level %d, key %s", znode->level, DBGKEY(key));
+
+ if (znode->alt)
+ /*
+ * We can no longer be sure of finding this znode by key, so we
+ * record it in the old_idx tree.
+ */
+ ins_clr_old_idx_znode(c, znode);
+
+ zn = kzalloc(c->max_znode_sz, GFP_NOFS);
+ if (!zn)
+ return -ENOMEM;
+ zn->parent = zp;
+ zn->level = znode->level;
+
+ /* Decide where to split */
+ if (znode->level == 0 && n == c->fanout &&
+ key_type(c, key) == UBIFS_DATA_KEY) {
+ union ubifs_key *key1;
+
+ /*
+ * If this is an inode which is being appended - do not split
+ * it because no other zbranches can be inserted between
+ * zbranches of consecutive data nodes anyway.
+ */
+ key1 = &znode->zbranch[n - 1].key;
+ if (key_ino(c, key1) == key_ino(c, key) &&
+ key_type(c, key1) == UBIFS_DATA_KEY &&
+ key_block(c, key1) == key_block(c, key) - 1)
+ appending = 1;
+ }
+
+ if (appending) {
+ keep = c->fanout;
+ move = 0;
+ } else {
+ keep = (c->fanout + 1) / 2;
+ move = c->fanout - keep;
+ }
+
+ /*
+ * Although we don't at present, we could look at the neighbors and see
+ * if we can move some zbranches there.
+ */
+
+ if (n < keep) {
+ /* Insert into existing znode */
+ zi = znode;
+ move += 1;
+ keep -= 1;
+ } else {
+ /* Insert into new znode */
+ zi = zn;
+ n -= keep;
+ /* Re-parent */
+ if (zn->level != 0)
+ zbr->znode->parent = zn;
+ }
+
+ __set_bit(DIRTY_ZNODE, &zn->flags);
+ atomic_long_inc(&c->dirty_zn_cnt);
+
+ zn->child_cnt = move;
+ znode->child_cnt = keep;
+
+ dbg_tnc("moving %d, keeping %d", move, keep);
+
+ /* Move zbranch */
+ for (i = 0; i < move; i++) {
+ zn->zbranch[i] = znode->zbranch[keep + i];
+ /* Re-parent */
+ if (zn->level != 0)
+ if (zn->zbranch[i].znode) {
+ zn->zbranch[i].znode->parent = zn;
+ zn->zbranch[i].znode->iip = i;
+ }
+ }
+
+ /* Insert new key and branch */
+ dbg_tnc("inserting at %d level %d, key %s", n, zn->level, DBGKEY(key));
+
+ insert_zbranch(zi, zbr, n);
+
+ /* Insert new znode (produced by spitting) into the parent */
+ if (zp) {
+ i = n;
+ /* Locate insertion point */
+ n = znode->iip + 1;
+ if (appending && n != c->fanout)
+ appending = 0;
+
+ if (i == 0 && zi == znode && znode->iip == 0)
+ correct_parent_keys(c, znode);
+
+ /* Tail recursion */
+ zbr->key = zn->zbranch[0].key;
+ zbr->znode = zn;
+ zbr->lnum = 0;
+ zbr->offs = 0;
+ zbr->len = 0;
+ znode = zp;
+
+ goto again;
+ }
+
+ /* We have to split root znode */
+ dbg_tnc("creating new zroot at level %d", znode->level + 1);
+
+ zi = kzalloc(c->max_znode_sz, GFP_NOFS);
+ if (!zi)
+ return -ENOMEM;
+
+ zi->child_cnt = 2;
+ zi->level = znode->level + 1;
+
+ __set_bit(DIRTY_ZNODE, &zi->flags);
+ atomic_long_inc(&c->dirty_zn_cnt);
+
+ zi->zbranch[0].key = znode->zbranch[0].key;
+ zi->zbranch[0].znode = znode;
+ zi->zbranch[0].lnum = c->zroot.lnum;
+ zi->zbranch[0].offs = c->zroot.offs;
+ zi->zbranch[0].len = c->zroot.len;
+ zi->zbranch[1].key = zn->zbranch[0].key;
+ zi->zbranch[1].znode = zn;
+
+ c->zroot.lnum = 0;
+ c->zroot.offs = 0;
+ c->zroot.len = 0;
+ c->zroot.znode = zi;
+
+ zn->parent = zi;
+ zn->iip = 1;
+ znode->parent = zi;
+ znode->iip = 0;
+
+ return 0;
+}
+
+/**
+ * ubifs_tnc_add - add a node to TNC.
+ * @c: UBIFS file-system description object
+ * @key: key to add
+ * @lnum: LEB number of node
+ * @offs: node offset
+ * @len: node length
+ *
+ * This function adds a node with key @key to TNC. The node may be new or it may
+ * obsolete some existing one. Returns %0 on success or negative error code on
+ * failure.
+ */
+int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
+ int offs, int len)
+{
+ int found, n, err = 0;
+ struct ubifs_znode *znode;
+
+ mutex_lock(&c->tnc_mutex);
+ dbg_tnc("%d:%d, len %d, key %s", lnum, offs, len, DBGKEY(key));
+ found = lookup_level0_dirty(c, key, &znode, &n);
+ if (!found) {
+ struct ubifs_zbranch zbr;
+
+ zbr.znode = NULL;
+ zbr.lnum = lnum;
+ zbr.offs = offs;
+ zbr.len = len;
+ key_copy(c, key, &zbr.key);
+ err = tnc_insert(c, znode, &zbr, n + 1);
+ } else if (found == 1) {
+ struct ubifs_zbranch *zbr = &znode->zbranch[n];
+
+ lnc_free(zbr);
+ err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
+ zbr->lnum = lnum;
+ zbr->offs = offs;
+ zbr->len = len;
+ } else
+ err = found;
+ if (!err)
+ err = dbg_check_tnc(c, 0);
+ mutex_unlock(&c->tnc_mutex);
+
+ return err;
+}
+
+/**
+ * ubifs_tnc_replace - replace a node in the TNC only if the old node is found.
+ * @c: UBIFS file-system description object
+ * @key: key to add
+ * @old_lnum: LEB number of old node
+ * @old_offs: old node offset
+ * @lnum: LEB number of node
+ * @offs: node offset
+ * @len: node length
+ *
+ * This function replaces a node with key @key in the TNC only if the old node
+ * is found. This function is called by garbage collection when node are moved.
+ * Returns %0 on success or negative error code on failure.
+ */
+int ubifs_tnc_replace(struct ubifs_info *c, const union ubifs_key *key,
+ int old_lnum, int old_offs, int lnum, int offs, int len)
+{
+ int found, n, err = 0;
+ struct ubifs_znode *znode;
+
+ mutex_lock(&c->tnc_mutex);
+ dbg_tnc("old LEB %d:%d, new LEB %d:%d, len %d, key %s", old_lnum,
+ old_offs, lnum, offs, len, DBGKEY(key));
+ found = lookup_level0_dirty(c, key, &znode, &n);
+ if (found < 0) {
+ err = found;
+ goto out_unlock;
+ }
+
+ if (found == 1) {
+ struct ubifs_zbranch *zbr = &znode->zbranch[n];
+
+ found = 0;
+ if (zbr->lnum == old_lnum && zbr->offs == old_offs) {
+ lnc_free(zbr);
+ err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
+ if (err)
+ goto out_unlock;
+ zbr->lnum = lnum;
+ zbr->offs = offs;
+ zbr->len = len;
+ found = 1;
+ } else if (is_hash_key(c, key)) {
+ found = resolve_collision_directly(c, key, &znode, &n,
+ old_lnum, old_offs);
+ dbg_tnc("rc returned %d, znode %p, n %d, LEB %d:%d",
+ found, znode, n, old_lnum, old_offs);
+ if (found < 0) {
+ err = found;
+ goto out_unlock;
+ }
+
+ if (found) {
+ /* Ensure the znode is dirtied */
+ if (znode->cnext || !ubifs_zn_dirty(znode)) {
+ znode = dirty_cow_bottom_up(c,
+ znode);
+ if (IS_ERR(znode)) {
+ err = PTR_ERR(znode);
+ goto out_unlock;
+ }
+ }
+ zbr = &znode->zbranch[n];
+ lnc_free(zbr);
+ err = ubifs_add_dirt(c, zbr->lnum,
+ zbr->len);
+ if (err)
+ goto out_unlock;
+ zbr->lnum = lnum;
+ zbr->offs = offs;
+ zbr->len = len;
+ }
+ }
+ }
+
+ if (!found)
+ err = ubifs_add_dirt(c, lnum, len);
+
+ if (!err)
+ err = dbg_check_tnc(c, 0);
+
+out_unlock:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * ubifs_tnc_add_nm - add a "hashed" node to TNC.
+ * @c: UBIFS file-system description object
+ * @key: key to add
+ * @lnum: LEB number of node
+ * @offs: node offset
+ * @len: node length
+ * @nm: node name
+ *
+ * This is the same as 'ubifs_tnc_add()' but it should be used with keys which
+ * may have collisions, like directory entry keys.
+ */
+int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
+ int lnum, int offs, int len, const struct qstr *nm)
+{
+ int found, n, err = 0;
+ struct ubifs_znode *znode;
+
+ mutex_lock(&c->tnc_mutex);
+ dbg_tnc("LEB %d:%d, name '%.*s', key %s", lnum, offs, nm->len, nm->name,
+ DBGKEY(key));
+ found = lookup_level0_dirty(c, key, &znode, &n);
+ if (found < 0) {
+ err = found;
+ goto out_unlock;
+ }
+
+ if (found == 1) {
+ if (c->replaying)
+ found = fallible_resolve_collision(c, key, &znode, &n,
+ nm, 1);
+ else
+ found = resolve_collision(c, key, &znode, &n, nm);
+ dbg_tnc("rc returned %d, znode %p, n %d", found, znode, n);
+ if (found < 0) {
+ err = found;
+ goto out_unlock;
+ }
+
+ /* Ensure the znode is dirtied */
+ if (znode->cnext || !ubifs_zn_dirty(znode)) {
+ znode = dirty_cow_bottom_up(c, znode);
+ if (IS_ERR(znode)) {
+ err = PTR_ERR(znode);
+ goto out_unlock;
+ }
+ }
+
+ if (found == 1) {
+ struct ubifs_zbranch *zbr = &znode->zbranch[n];
+
+ lnc_free(zbr);
+ err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
+ zbr->lnum = lnum;
+ zbr->offs = offs;
+ zbr->len = len;
+ goto out_unlock;
+ }
+ }
+
+ if (!found) {
+ struct ubifs_zbranch zbr;
+
+ zbr.znode = NULL;
+ zbr.lnum = lnum;
+ zbr.offs = offs;
+ zbr.len = len;
+ key_copy(c, key, &zbr.key);
+ err = tnc_insert(c, znode, &zbr, n + 1);
+ if (err)
+ goto out_unlock;
+ if (c->replaying && c->replay_sqnum < c->cs_sqnum) {
+ /*
+ * This node was moved by garbage collection. We can
+ * tell because it is in the journal but it has a
+ * sequence number earlier than the last commit-start.
+ * We did not find it in the index so there may be a
+ * dangling branch still in the index. So we remove it
+ * by passing 'ubifs_tnc_remove_nm()' the same key but
+ * an unmatchable name.
+ */
+ struct qstr noname = { .len = 0, .name = "" };
+
+ err = dbg_check_tnc(c, 0);
+ mutex_unlock(&c->tnc_mutex);
+ if (err)
+ return err;
+ return ubifs_tnc_remove_nm(c, key, &noname);
+ }
+ }
+
+out_unlock:
+ if (!err)
+ err = dbg_check_tnc(c, 0);
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * tnc_delete - delete a znode form TNC.
+ * @c: UBIFS file-system description object
+ * @znode: znode to delete from
+ * @n: zbranch slot number to delete
+ *
+ * This function deletes a leaf node from @n-th slot of @znode. Returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+static int tnc_delete(struct ubifs_info *c, struct ubifs_znode *znode, int n)
+{
+ struct ubifs_zbranch *zbr;
+ struct ubifs_znode *zp;
+ int i, err;
+
+ /* Delete without merge for now */
+ ubifs_assert(znode->level == 0);
+ ubifs_assert(n >= 0 && n < c->fanout);
+ dbg_tnc("deleting %s", DBGKEY(&znode->zbranch[n].key));
+
+ zbr = &znode->zbranch[n];
+ lnc_free(zbr);
+
+ err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
+ if (err) {
+ dbg_dump_znode(c, znode);
+ return err;
+ }
+
+ /* We do not "gap" zbranch slots */
+ for (i = n; i < znode->child_cnt - 1; i++)
+ znode->zbranch[i] = znode->zbranch[i + 1];
+ znode->child_cnt -= 1;
+
+ if (znode->child_cnt > 0)
+ return 0;
+
+ /*
+ * This was the last zbranch, we have to delete this znode from the
+ * parent.
+ */
+
+ do {
+ ubifs_assert(!test_bit(OBSOLETE_ZNODE, &znode->flags));
+ ubifs_assert(ubifs_zn_dirty(znode));
+
+ zp = znode->parent;
+ n = znode->iip;
+
+ atomic_long_dec(&c->dirty_zn_cnt);
+
+ err = insert_old_idx_znode(c, znode);
+ if (err)
+ return err;
+
+ if (znode->cnext) {
+ __set_bit(OBSOLETE_ZNODE, &znode->flags);
+ atomic_long_inc(&c->clean_zn_cnt);
+ atomic_long_inc(&ubifs_clean_zn_cnt);
+ } else
+ kfree(znode);
+ znode = zp;
+ } while (znode->child_cnt == 1); /* while removing last child */
+
+ /* Remove from znode, entry n - 1 */
+ znode->child_cnt -= 1;
+ ubifs_assert(znode->level != 0);
+ for (i = n; i < znode->child_cnt; i++) {
+ znode->zbranch[i] = znode->zbranch[i + 1];
+ if (znode->zbranch[i].znode)
+ znode->zbranch[i].znode->iip = i;
+ }
+
+ /*
+ * If this is the root and it has only 1 child then
+ * collapse the tree.
+ */
+ if (!znode->parent) {
+ while (znode->child_cnt == 1 && znode->level != 0) {
+ zp = znode;
+ zbr = &znode->zbranch[0];
+ znode = get_znode(c, znode, 0);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ znode = dirty_cow_znode(c, zbr);
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+ znode->parent = NULL;
+ znode->iip = 0;
+ if (c->zroot.len) {
+ err = insert_old_idx(c, c->zroot.lnum,
+ c->zroot.offs);
+ if (err)
+ return err;
+ }
+ c->zroot.lnum = zbr->lnum;
+ c->zroot.offs = zbr->offs;
+ c->zroot.len = zbr->len;
+ c->zroot.znode = znode;
+ ubifs_assert(!test_bit(OBSOLETE_ZNODE,
+ &zp->flags));
+ ubifs_assert(test_bit(DIRTY_ZNODE, &zp->flags));
+ atomic_long_dec(&c->dirty_zn_cnt);
+
+ if (zp->cnext) {
+ __set_bit(OBSOLETE_ZNODE, &zp->flags);
+ atomic_long_inc(&c->clean_zn_cnt);
+ atomic_long_inc(&ubifs_clean_zn_cnt);
+ } else
+ kfree(zp);
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * ubifs_tnc_remove - remove an index entry of a node.
+ * @c: UBIFS file-system description object
+ * @key: key of node
+ *
+ * Returns %0 on success or negative error code on failure.
+ */
+int ubifs_tnc_remove(struct ubifs_info *c, const union ubifs_key *key)
+{
+ int found, n, err = 0;
+ struct ubifs_znode *znode;
+
+ mutex_lock(&c->tnc_mutex);
+ dbg_tnc("key %s", DBGKEY(key));
+ found = lookup_level0_dirty(c, key, &znode, &n);
+ if (found < 0) {
+ err = found;
+ goto out_unlock;
+ }
+ if (found == 1)
+ err = tnc_delete(c, znode, n);
+ if (!err)
+ err = dbg_check_tnc(c, 0);
+
+out_unlock:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * ubifs_tnc_remove_nm - remove an index entry for a "hashed" node.
+ * @c: UBIFS file-system description object
+ * @key: key of node
+ * @nm: directory entry name
+ *
+ * Returns %0 on success or negative error code on failure.
+ */
+int ubifs_tnc_remove_nm(struct ubifs_info *c, const union ubifs_key *key,
+ const struct qstr *nm)
+{
+ int n, err;
+ struct ubifs_znode *znode;
+
+ mutex_lock(&c->tnc_mutex);
+ dbg_tnc("%.*s, key %s", nm->len, nm->name, DBGKEY(key));
+ err = lookup_level0_dirty(c, key, &znode, &n);
+ if (err < 0)
+ goto out_unlock;
+
+ if (err) {
+ if (c->replaying)
+ err = fallible_resolve_collision(c, key, &znode, &n,
+ nm, 0);
+ else
+ err = resolve_collision(c, key, &znode, &n, nm);
+ dbg_tnc("rc returned %d, znode %p, n %d", err, znode, n);
+ if (err < 0)
+ goto out_unlock;
+ if (err) {
+ /* Ensure the znode is dirtied */
+ if (znode->cnext || !ubifs_zn_dirty(znode)) {
+ znode = dirty_cow_bottom_up(c, znode);
+ if (IS_ERR(znode)) {
+ err = PTR_ERR(znode);
+ goto out_unlock;
+ }
+ }
+ err = tnc_delete(c, znode, n);
+ }
+ }
+
+out_unlock:
+ if (!err)
+ err = dbg_check_tnc(c, 0);
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * key_in_range - determine if a key falls within a range of keys.
+ * @c: UBIFS file-system description object
+ * @key: key to check
+ * @from_key: lowest key in range
+ * @to_key: highest key in range
+ *
+ * This function returns %1 if the key is in range and %0 otherwise.
+ */
+static int key_in_range(struct ubifs_info *c, union ubifs_key *key,
+ union ubifs_key *from_key, union ubifs_key *to_key)
+{
+ if (keys_cmp(c, key, from_key) < 0)
+ return 0;
+ if (keys_cmp(c, key, to_key) > 0)
+ return 0;
+ return 1;
+}
+
+/**
+ * ubifs_tnc_remove_range - remove index entries in range.
+ * @c: UBIFS file-system description object
+ * @from_key: lowest key to remove
+ * @to_key: highest key to remove
+ *
+ * This function removes index entries starting at @from_key and ending at
+ * @to_key. This function returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+int ubifs_tnc_remove_range(struct ubifs_info *c, union ubifs_key *from_key,
+ union ubifs_key *to_key)
+{
+ int i, n, k, err = 0;
+ struct ubifs_znode *znode;
+ union ubifs_key *key;
+
+ mutex_lock(&c->tnc_mutex);
+ while (1) {
+ /* Find first level 0 znode that contains keys to remove */
+ err = lookup_level0(c, from_key, &znode, &n);
+ if (err < 0)
+ goto out_unlock;
+
+ if (err)
+ key = from_key;
+ else {
+ err = tnc_next(c, &znode, &n);
+ if (err == -ENOENT) {
+ err = 0;
+ goto out_unlock;
+ }
+ if (err < 0)
+ goto out_unlock;
+ key = &znode->zbranch[n].key;
+ if (!key_in_range(c, key, from_key, to_key)) {
+ err = 0;
+ goto out_unlock;
+ }
+ }
+
+ /* Ensure the znode is dirtied */
+ if (znode->cnext || !ubifs_zn_dirty(znode)) {
+ znode = dirty_cow_bottom_up(c, znode);
+ if (IS_ERR(znode)) {
+ err = PTR_ERR(znode);
+ goto out_unlock;
+ }
+ }
+
+ /* Remove all keys in range except the first */
+ for (i = n + 1, k = 0; i < znode->child_cnt; i++, k++) {
+ key = &znode->zbranch[i].key;
+ if (!key_in_range(c, key, from_key, to_key))
+ break;
+ lnc_free(&znode->zbranch[i]);
+ err = ubifs_add_dirt(c, znode->zbranch[i].lnum,
+ znode->zbranch[i].len);
+ if (err) {
+ dbg_dump_znode(c, znode);
+ goto out_unlock;
+ }
+ dbg_tnc("removing %s", DBGKEY(key));
+ }
+ if (k) {
+ for (i = n + 1 + k; i < znode->child_cnt; i++)
+ znode->zbranch[i - k] = znode->zbranch[i];
+ znode->child_cnt -= k;
+ }
+
+ /* Now delete the first */
+ err = tnc_delete(c, znode, n);
+ if (err)
+ goto out_unlock;
+ }
+
+out_unlock:
+ if (!err)
+ err = dbg_check_tnc(c, 0);
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * ubifs_tnc_remove_ino - remove an inode from TNC.
+ * @c: UBIFS file-system description object
+ * @inum: inode number to remove
+ *
+ * This function remove inode @inum and all the extended attributes associated
+ * with the anode from TNC and returns zero in case of success or a negative
+ * error code in case of failure.
+ */
+int ubifs_tnc_remove_ino(struct ubifs_info *c, ino_t inum)
+{
+ union ubifs_key key1, key2;
+ struct ubifs_dent_node *xent, *pxent = NULL;
+ struct qstr nm = { .name = NULL };
+
+ dbg_tnc("ino %lu", inum);
+
+ /*
+ * Walk all extended attribute entries and remove them together with
+ * corresponding extended attribute inodes.
+ */
+ lowest_xent_key(c, &key1, inum);
+ while (1) {
+ ino_t xattr_inum;
+ int err;
+
+ xent = ubifs_tnc_next_ent(c, &key1, &nm);
+ if (IS_ERR(xent)) {
+ err = PTR_ERR(xent);
+ if (err == -ENOENT)
+ break;
+ return err;
+ }
+
+ xattr_inum = le64_to_cpu(xent->inum);
+ dbg_tnc("xent '%s', ino %lu", xent->name, xattr_inum);
+
+ nm.name = xent->name;
+ nm.len = le16_to_cpu(xent->nlen);
+ err = ubifs_tnc_remove_nm(c, &key1, &nm);
+ if (err) {
+ kfree(xent);
+ return err;
+ }
+
+ lowest_ino_key(c, &key1, xattr_inum);
+ highest_ino_key(c, &key2, xattr_inum);
+ err = ubifs_tnc_remove_range(c, &key1, &key2);
+ if (err) {
+ kfree(xent);
+ return err;
+ }
+
+ kfree(pxent);
+ pxent = xent;
+ key_read(c, &xent->key, &key1);
+ }
+
+ kfree(pxent);
+ lowest_ino_key(c, &key1, inum);
+ highest_ino_key(c, &key2, inum);
+
+ return ubifs_tnc_remove_range(c, &key1, &key2);
+}
+
+/**
+ * ubifs_tnc_next_ent - walk directory or extended attribute entries.
+ * @c: UBIFS file-system description object
+ * @key: key of last entry
+ * @nm: name of last entry found or %NULL
+ *
+ * This function finds and reads the next directory or extended attribute entry
+ * after the given key (@key) if there is one. @nm is used to resolve
+ * collisions.
+ *
+ * If the name of the current entry is not known and only the key is known,
+ * @nm->name has to be %NULL. In this case the semantics of this function is a
+ * little bit different and it returns the entry corresponding to this key, not
+ * the next one. If the key was not found, the closest "right" entry is
+ * returned.
+ *
+ * If the fist entry has to be found, @key has to contain the lowest possible
+ * key value for this inode and @name has to be %NULL.
+ *
+ * This function returns the found directory or extended attribute entry node
+ * in case of success, %-ENOENT is returned if no entry was found, and a
+ * negative error code is returned in case of failure.
+ */
+struct ubifs_dent_node *ubifs_tnc_next_ent(struct ubifs_info *c,
+ union ubifs_key *key,
+ const struct qstr *nm)
+{
+ int n, err, type = key_type(c, key);
+ struct ubifs_znode *znode;
+ struct ubifs_dent_node *dent;
+ struct ubifs_zbranch *zbr;
+ union ubifs_key *dkey;
+
+ dbg_tnc("%s %s", nm->name ? (char *)nm->name : "(lowest)", DBGKEY(key));
+ ubifs_assert(is_hash_key(c, key));
+
+ mutex_lock(&c->tnc_mutex);
+ err = lookup_level0(c, key, &znode, &n);
+ if (unlikely(err < 0))
+ goto out_unlock;
+
+ if (nm->name) {
+ if (err) {
+ /* Handle collisions */
+ err = resolve_collision(c, key, &znode, &n, nm);
+ dbg_tnc("rc returned %d, znode %p, n %d",
+ err, znode, n);
+ if (unlikely(err < 0))
+ goto out_unlock;
+ }
+
+ /* Now find next entry */
+ err = tnc_next(c, &znode, &n);
+ if (unlikely(err))
+ goto out_unlock;
+ } else {
+ /*
+ * The full name of the entry was not given, in which case the
+ * behavior of this function is a little different and it
+ * returns current entry, not the next one.
+ */
+ if (!err) {
+ /*
+ * However, the given key does not exist in the TNC
+ * tree and @znode/@n variables contain the closest
+ * "preceding" element. Switch to the next one.
+ */
+ err = tnc_next(c, &znode, &n);
+ if (err)
+ goto out_unlock;
+ }
+ }
+
+ zbr = &znode->zbranch[n];
+ dent = kmalloc(zbr->len, GFP_NOFS);
+ if (unlikely(!dent)) {
+ err = -ENOMEM;
+ goto out_unlock;
+ }
+
+ /*
+ * The above 'tnc_next()' call could lead us to the next inode, check
+ * this.
+ */
+ dkey = &zbr->key;
+ if (key_ino(c, dkey) != key_ino(c, key) ||
+ key_type(c, dkey) != type) {
+ err = -ENOENT;
+ goto out_free;
+ }
+
+ err = tnc_read_node_nm(c, zbr, dent);
+ if (unlikely(err))
+ goto out_free;
+
+ mutex_unlock(&c->tnc_mutex);
+ return dent;
+
+out_free:
+ kfree(dent);
+out_unlock:
+ mutex_unlock(&c->tnc_mutex);
+ return ERR_PTR(err);
+}
+
+/**
+ * tnc_destroy_cnext - destroy left-over obsolete znodes from a failed commit.
+ * @c: UBIFS file-system description object
+ *
+ * Destroy left-over obsolete znodes from a failed commit.
+ */
+static void tnc_destroy_cnext(struct ubifs_info *c)
+{
+ struct ubifs_znode *cnext;
+
+ if (!c->cnext)
+ return;
+ ubifs_assert(c->cmt_state == COMMIT_BROKEN);
+ cnext = c->cnext;
+ do {
+ struct ubifs_znode *znode = cnext;
+
+ cnext = cnext->cnext;
+ if (test_bit(OBSOLETE_ZNODE, &znode->flags))
+ kfree(znode);
+ } while (cnext && cnext != c->cnext);
+}
+
+/**
+ * ubifs_tnc_close - close TNC subsystem and free all related resources.
+ * @c: UBIFS file-system description object
+ */
+void ubifs_tnc_close(struct ubifs_info *c)
+{
+ long clean_freed;
+
+ tnc_destroy_cnext(c);
+ if (c->zroot.znode) {
+ clean_freed = ubifs_destroy_tnc_subtree(c->zroot.znode);
+ atomic_long_sub(clean_freed, &ubifs_clean_zn_cnt);
+ }
+ kfree(c->gap_lebs);
+ kfree(c->ilebs);
+ destroy_old_idx(c);
+}
+
+/**
+ * left_znode - get the znode to the left.
+ * @c: UBIFS file-system description object
+ * @znode: znode
+ *
+ * This function returns a pointer to the znode to the left of @znode or NULL if
+ * there is not one. A negative error code is returned on failure.
+ */
+static struct ubifs_znode *left_znode(struct ubifs_info *c,
+ struct ubifs_znode *znode)
+{
+ int level = znode->level;
+
+ while (1) {
+ int n = znode->iip - 1;
+
+ /* Go up until we can go left */
+ znode = znode->parent;
+ if (!znode)
+ return NULL;
+ if (n >= 0) {
+ /* Now go down the rightmost branch to 'level' */
+ znode = get_znode(c, znode, n);
+ if (IS_ERR(znode))
+ return znode;
+ while (znode->level != level) {
+ n = znode->child_cnt - 1;
+ znode = get_znode(c, znode, n);
+ if (IS_ERR(znode))
+ return znode;
+ }
+ break;
+ }
+ }
+ return znode;
+}
+
+/**
+ * right_znode - get the znode to the right.
+ * @c: UBIFS file-system description object
+ * @znode: znode
+ *
+ * This function returns a pointer to the znode to the right of @znode or NULL
+ * if there is not one. A negative error code is returned on failure.
+ */
+static struct ubifs_znode *right_znode(struct ubifs_info *c,
+ struct ubifs_znode *znode)
+{
+ int level = znode->level;
+
+ while (1) {
+ int n = znode->iip + 1;
+
+ /* Go up until we can go right */
+ znode = znode->parent;
+ if (!znode)
+ return NULL;
+ if (n < znode->child_cnt) {
+ /* Now go down the leftmost branch to 'level' */
+ znode = get_znode(c, znode, n);
+ if (IS_ERR(znode))
+ return znode;
+ while (znode->level != level) {
+ znode = get_znode(c, znode, 0);
+ if (IS_ERR(znode))
+ return znode;
+ }
+ break;
+ }
+ }
+ return znode;
+}
+
+/**
+ * lookup_znode - find a particular indexing node from TNC.
+ * @c: UBIFS file-system description object
+ * @key: index node key to lookup
+ * @level: index node level
+ * @lnum: index node LEB number
+ * @offs: index node offset
+ *
+ * This function searches an indexing node by its first key @key and its
+ * address @lnum:@offs. It looks up the indexing tree by pulling all indexing
+ * nodes it traverses to TNC. This function is called fro indexing nodes which
+ * were found on the media by scanning, for example when garbage-collecting or
+ * when doing in-the-gaps commit. This means that the indexing node which is
+ * looked for does not have to have exactly the same leftmost key @key, because
+ * the leftmost key may have been changed, in which case TNC will contain a
+ * dirty znode which still refers the same @lnum:@offs. This function is clever
+ * enough to recognize such indexing nodes.
+ *
+ * Note, if a znode was deleted or changed too much, then this function will
+ * not find it. For situations like this UBIFS has the old index RB-tree
+ * (indexed by @lnum:@offs).
+ *
+ * This function returns a pointer to the znode found or %NULL if it is not
+ * found. A negative error code is returned on failure.
+ */
+static struct ubifs_znode *lookup_znode(struct ubifs_info *c,
+ union ubifs_key *key, int level,
+ int lnum, int offs)
+{
+ struct ubifs_znode *znode, *zn;
+ int n, nn;
+
+ /*
+ * The arguments have probably been read off flash, so don't assume
+ * they are valid.
+ */
+ if (level < 0)
+ return ERR_PTR(-EINVAL);
+
+ /* Get the root znode */
+ znode = c->zroot.znode;
+ if (!znode) {
+ znode = load_znode(c, &c->zroot, NULL, 0);
+ if (IS_ERR(znode))
+ return znode;
+ }
+ /* Check if it is the one we are looking for */
+ if (c->zroot.lnum == lnum && c->zroot.offs == offs)
+ return znode;
+ /* Descend to the parent level i.e. (level + 1) */
+ if (level >= znode->level)
+ return NULL;
+ while (1) {
+ ubifs_search_zbranch(c, znode, key, &n);
+ if (n < 0) {
+ /*
+ * We reached a znode where the leftmost key is greater
+ * than the key we are searching for. This is the same
+ * situation as the one described in a huge comment at
+ * the end of the 'lookup_level0()' function. And for
+ * exactly the same reasons we have to try to look left
+ * before giving up.
+ */
+ znode = left_znode(c, znode);
+ if (!znode)
+ return NULL;
+ if (IS_ERR(znode))
+ return znode;
+ ubifs_search_zbranch(c, znode, key, &n);
+ ubifs_assert(n >= 0);
+ }
+ if (znode->level == level + 1)
+ break;
+ znode = get_znode(c, znode, n);
+ if (IS_ERR(znode))
+ return znode;
+ }
+ /* Check if the child is the one we are looking for */
+ if (znode->zbranch[n].lnum == lnum && znode->zbranch[n].offs == offs)
+ return get_znode(c, znode, n);
+ /* If the key is unique, there is nowhere else to look */
+ if (!is_hash_key(c, key))
+ return NULL;
+ /*
+ * The key is not unique and so may be also in the znodes to either
+ * side.
+ */
+ zn = znode;
+ nn = n;
+ /* Look left */
+ while (1) {
+ /* Move one branch to the left */
+ if (n)
+ n -= 1;
+ else {
+ znode = left_znode(c, znode);
+ if (!znode)
+ break;
+ if (IS_ERR(znode))
+ return znode;
+ n = znode->child_cnt - 1;
+ }
+ /* Check it */
+ if (znode->zbranch[n].lnum == lnum &&
+ znode->zbranch[n].offs == offs)
+ return get_znode(c, znode, n);
+ /* Stop if the key is less than the one we are looking for */
+ if (keys_cmp(c, &znode->zbranch[n].key, key) < 0)
+ break;
+ }
+ /* Back to the middle */
+ znode = zn;
+ n = nn;
+ /* Look right */
+ while (1) {
+ /* Move one branch to the right */
+ if (++n >= znode->child_cnt) {
+ znode = right_znode(c, znode);
+ if (!znode)
+ break;
+ if (IS_ERR(znode))
+ return znode;
+ n = 0;
+ }
+ /* Check it */
+ if (znode->zbranch[n].lnum == lnum &&
+ znode->zbranch[n].offs == offs)
+ return get_znode(c, znode, n);
+ /* Stop if the key is greater than the one we are looking for */
+ if (keys_cmp(c, &znode->zbranch[n].key, key) > 0)
+ break;
+ }
+ return NULL;
+}
+
+/**
+ * is_idx_node_in_tnc - determine if an index node is in the TNC.
+ * @c: UBIFS file-system description object
+ * @key: key of index node
+ * @level: index node level
+ * @lnum: LEB number of index node
+ * @offs: offset of index node
+ *
+ * This function returns %0 if the index node is not referred to in the TNC, %1
+ * if the index node is referred to in the TNC and the corresponding znode is
+ * dirty, %2 if an index node is referred to in the TNC and the corresponding
+ * znode is clean, and a negative error code in case of failure.
+ *
+ * Note, the @key argument has to be the key of the first child. Also note,
+ * this function relies on the fact that 0:0 is never a valid LEB number and
+ * offset for a main-area node.
+ */
+int is_idx_node_in_tnc(struct ubifs_info *c, union ubifs_key *key, int level,
+ int lnum, int offs)
+{
+ struct ubifs_znode *znode;
+
+ znode = lookup_znode(c, key, level, lnum, offs);
+ if (!znode)
+ return 0;
+ if (IS_ERR(znode))
+ return PTR_ERR(znode);
+
+ return ubifs_zn_dirty(znode) ? 1 : 2;
+}
+
+/**
+ * is_leaf_node_in_tnc - determine if a non-indexing not is in the TNC.
+ * @c: UBIFS file-system description object
+ * @key: node key
+ * @lnum: node LEB number
+ * @offs: node offset
+ *
+ * This function returns %1 if the node is referred to in the TNC, %0 if it is
+ * not, and a negative error code in case of failure.
+ *
+ * Note, this function relies on the fact that 0:0 is never a valid LEB number
+ * and offset for a main-area node.
+ */
+static int is_leaf_node_in_tnc(struct ubifs_info *c, union ubifs_key *key,
+ int lnum, int offs)
+{
+ struct ubifs_zbranch *zbr;
+ struct ubifs_znode *znode, *zn;
+ int n, found, err, nn;
+ const int unique = !is_hash_key(c, key);
+
+ found = lookup_level0(c, key, &znode, &n);
+ if (found < 0)
+ return found; /* Error code */
+ if (!found)
+ return 0;
+ zbr = &znode->zbranch[n];
+ if (lnum == zbr->lnum && offs == zbr->offs)
+ return 1; /* Found it */
+ if (unique)
+ return 0;
+ /*
+ * Because the key is not unique, we have to look left
+ * and right as well
+ */
+ zn = znode;
+ nn = n;
+ /* Look left */
+ while (1) {
+ err = tnc_prev(c, &znode, &n);
+ if (err == -ENOENT)
+ break;
+ if (err)
+ return err;
+ if (keys_cmp(c, key, &znode->zbranch[n].key))
+ break;
+ zbr = &znode->zbranch[n];
+ if (lnum == zbr->lnum && offs == zbr->offs)
+ return 1; /* Found it */
+ }
+ /* Look right */
+ znode = zn;
+ n = nn;
+ while (1) {
+ err = tnc_next(c, &znode, &n);
+ if (err) {
+ if (err == -ENOENT)
+ return 0;
+ return err;
+ }
+ if (keys_cmp(c, key, &znode->zbranch[n].key))
+ break;
+ zbr = &znode->zbranch[n];
+ if (lnum == zbr->lnum && offs == zbr->offs)
+ return 1; /* Found it */
+ }
+ return 0;
+}
+
+/**
+ * ubifs_tnc_has_node - determine whether a node is in the TNC.
+ * @c: UBIFS file-system description object
+ * @key: node key
+ * @level: index node level (if it is an index node)
+ * @lnum: node LEB number
+ * @offs: node offset
+ * @is_idx: non-zero if the node is an index node
+ *
+ * This function returns %1 if the node is in the TNC, %0 if it is not, and a
+ * negative error code in case of failure. For index nodes, @key has to be the
+ * key of the first child. An index node is considered to be in the TNC only if
+ * the corresponding znode is clean or has not been loaded.
+ */
+int ubifs_tnc_has_node(struct ubifs_info *c, union ubifs_key *key, int level,
+ int lnum, int offs, int is_idx)
+{
+ int err;
+
+ mutex_lock(&c->tnc_mutex);
+ if (is_idx) {
+ err = is_idx_node_in_tnc(c, key, level, lnum, offs);
+ if (err < 0)
+ goto out_unlock;
+ if (err == 1)
+ /* The index node was found but it was dirty */
+ err = 0;
+ else if (err == 2)
+ /* The index node was found and it was clean */
+ err = 1;
+ else
+ BUG_ON(err != 0);
+ } else
+ err = is_leaf_node_in_tnc(c, key, lnum, offs);
+
+out_unlock:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+/**
+ * ubifs_dirty_idx_node - dirty an index node.
+ * @c: UBIFS file-system description object
+ * @key: index node key
+ * @level: index node level
+ * @lnum: index node LEB number
+ * @offs: index node offset
+ *
+ * This function loads and dirties an index node so that it can be garbage
+ * collected. The @key argument has to be the key of the first child. This
+ * function relies on the fact that 0:0 is never a valid LEB number and offset
+ * for a main-area node. Returns %0 on success and a negative error code on
+ * failure.
+ */
+int ubifs_dirty_idx_node(struct ubifs_info *c, union ubifs_key *key, int level,
+ int lnum, int offs)
+{
+ struct ubifs_znode *znode;
+ int err = 0;
+
+ mutex_lock(&c->tnc_mutex);
+ znode = lookup_znode(c, key, level, lnum, offs);
+ if (!znode)
+ goto out_unlock;
+ if (IS_ERR(znode)) {
+ err = PTR_ERR(znode);
+ goto out_unlock;
+ }
+ znode = dirty_cow_bottom_up(c, znode);
+ if (IS_ERR(znode)) {
+ err = PTR_ERR(znode);
+ goto out_unlock;
+ }
+
+out_unlock:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+
+/**
+ * dbg_walk_sub_tree - walk index subtree.
+ * @c: UBIFS file-system description object
+ * @znode: root znode of the subtree to walk
+ * @leaf_cb: called for each leaf node
+ * @znode_cb: called for each indexing node
+ * @priv: private date which is passed to callbacks
+ *
+ * This is a helper function which recursively walks the UBIFS index, reading
+ * each indexing node from the media if needed. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+static int dbg_walk_sub_tree(struct ubifs_info *c, struct ubifs_znode *znode,
+ dbg_leaf_callback leaf_cb,
+ dbg_znode_callback znode_cb, void *priv)
+{
+ int n, err;
+
+ cond_resched();
+
+ if (znode_cb) {
+ err = znode_cb(c, znode, priv);
+ if (err)
+ return err;
+ }
+
+ if (znode->level == 0) {
+ if (!leaf_cb)
+ return 0;
+
+ for (n = 0; n < znode->child_cnt; n++) {
+ struct ubifs_zbranch *zbr = &znode->zbranch[n];
+
+ err = leaf_cb(c, zbr, priv);
+ if (err)
+ return err;
+ }
+ } else
+ for (n = 0; n < znode->child_cnt; n++) {
+ struct ubifs_znode *zn;
+
+ zn = get_znode(c, znode, n);
+ if (IS_ERR(zn))
+ return PTR_ERR(zn);
+ err = dbg_walk_sub_tree(c, zn, leaf_cb, znode_cb, priv);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+/**
+ * dbg_walk_index - walk the on-flash index.
+ * @c: UBIFS file-system description object
+ * @leaf_cb: called for each leaf node
+ * @znode_cb: called for each indexing node
+ * @priv: private date which is passed to callbacks
+ *
+ * This function walks the UBIFS index and calls the @leaf_cb for each leaf
+ * node and @znode_cb for each indexing node. Returns zero in case of success
+ * and a negative error code in case of failure.
+ *
+ * Because 'dbg_walk_sub_tree()' is recursive, it runs the risk of exceeding the
+ * stack space.
+ *
+ * It would be better if this function removed every znode it pulled to into
+ * the TNC, so that the behavior more closely matched the non-debugging
+ * behavior.
+ */
+int dbg_walk_index(struct ubifs_info *c, dbg_leaf_callback leaf_cb,
+ dbg_znode_callback znode_cb, void *priv)
+{
+ int err = 0;
+
+ mutex_lock(&c->tnc_mutex);
+ if (!c->zroot.znode) {
+ c->zroot.znode = load_znode(c, &c->zroot, NULL, 0);
+ if (IS_ERR(c->zroot.znode)) {
+ err = PTR_ERR(c->zroot.znode);
+ c->zroot.znode = NULL;
+ goto out_unlock;
+ }
+ }
+
+ err = dbg_walk_sub_tree(c, c->zroot.znode, leaf_cb, znode_cb, priv);
+
+out_unlock:
+ mutex_unlock(&c->tnc_mutex);
+ return err;
+}
+
+int dbg_read_leaf_nolock(struct ubifs_info *c, struct ubifs_zbranch *zbr,
+ void *node)
+{
+ ubifs_assert(mutex_is_locked(&c->tnc_mutex));
+ if (is_hash_key(c, &zbr->key))
+ return tnc_read_node_nm(c, zbr, node);
+ return tnc_read_node(c, zbr, node);
+}
+
+#endif /* CONFIG_UBIFS_FS_DEBUG */
--
1.5.4.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists