path: root/file.c

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <assert.h>
#include <inttypes.h>
#include <lk/macros.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

#include "block_allocator.h"
#include "block_map.h"
#include "crypt.h"
#include "debug.h"
#include "file.h"
#include "transaction.h"

#define BIT_MASK(x) \
    (((x) >= sizeof(uint64_t) * 8) ? (~0ULL) : ((1ULL << (x)) - 1))

#define FILE_ENTRY_MAGIC (0x0066797473757274) /* trustyf\0 */

/**
 * struct file_entry - On-disk file entry
 * @iv:         initial value used for encrypt/decrypt
 * @magic:      FILE_ENTRY_MAGIC.
 * @block_map:  Block and mac of file block map root node.
 * @size:       File size in bytes.
 * @reserved:   Reserved for future use. Write 0, read ignore.
 * @path:       File path and name.
 */
struct file_entry {
    struct iv iv;
    uint64_t magic;
    struct block_mac block_map;
    struct file_info info;
};

static bool file_tree_lookup(struct block_mac* block_mac_out,
                             struct transaction* tr,
                             struct block_tree* tree,
                             struct block_tree_path* tree_path,
                             const char* file_path,
                             bool remove);

/**
 * path_hash - Convert a path string to hash value
 * @tr:         Transaction object.
 * @path:       String to calculate hash for.
 *
 * Return: non-zero hash value that fits in @tr->fs->block_num_size bytes
 * computed from @path
 */
static data_block_t path_hash(struct transaction* tr, const char* path) {
    data_block_t hash = str_hash(path);

    hash &= BIT_MASK(tr->fs->block_num_size * 8);
    if (!hash) {
        hash++; /* 0 key is not supported by block_tree */
    }

    return hash;
}

/**
 * file_block_map_init - Initialize in-memory block map state from file entry
 * @tr:         Transaction object.
 * @block_map:  Block map object.
 * @file:       Block number and mac of file entry.
 *
 * Load file entry at @file and initialize @block_map with root node stored
 * there.
 */
void file_block_map_init(struct transaction* tr,
                         struct block_map* block_map,
                         const struct block_mac* file) {
    const struct file_entry* file_entry_ro;
    struct obj_ref file_entry_ro_ref = OBJ_REF_INITIAL_VALUE(file_entry_ro_ref);

    if (!block_mac_valid(tr, file)) {
        goto err;
    }
    file_entry_ro = block_get(tr, file, NULL, &file_entry_ro_ref);
    if (!file_entry_ro) {
        goto err;
    }
    assert(file_entry_ro);
    block_map_init(tr, block_map, &file_entry_ro->block_map,
                   tr->fs->dev->block_size);
    block_put(file_entry_ro, &file_entry_ro_ref);

    return;

err:
    if (tr->failed) {
        pr_warn("can't read file entry at %" PRIu64 ", transaction failed\n",
                block_mac_to_block(tr, file));
    } else {
        pr_err("can't read file entry at %" PRIu64 "\n",
               block_mac_to_block(tr, file));
        transaction_fail(tr);
    }
}

/**
 * file_print - Print information about a file
 * @tr:         Transaction object.
 * @file:       File handle object.
 */
void file_print(struct transaction* tr,
                const struct storage_file_handle* file) {
    const struct file_entry* file_entry_ro;
    struct obj_ref file_entry_ro_ref = OBJ_REF_INITIAL_VALUE(file_entry_ro_ref);
    struct block_map block_map;

    file_block_map_init(tr, &block_map, &file->block_mac);
    file_entry_ro = block_get(tr, &file->block_mac, NULL, &file_entry_ro_ref);
    if (!file_entry_ro) {
        printf("can't read file entry at %" PRIu64 "\n",
               block_mac_to_block(tr, &file->block_mac));
        return;
    }
    assert(file_entry_ro);
    printf("file at %" PRIu64 ", path %s, size %" PRIu64 ", hash 0x%" PRIx64
           ", block map (tree)\n",
           block_mac_to_block(tr, &file->block_mac), file_entry_ro->info.path,
           file_entry_ro->info.size, path_hash(tr, file_entry_ro->info.path));
    block_put(file_entry_ro, &file_entry_ro_ref);
    block_tree_print(tr, &block_map.tree);
}

/**
 * files_print - Print information about all committed files
 * @tr:         Transaction object.
 */
void files_print(struct transaction* tr) {
    struct block_tree_path path;
    struct storage_file_handle file;

    printf("%s: files:\n", __func__);
    block_tree_print(tr, &tr->fs->files);

    block_tree_walk(tr, &tr->fs->files, 0, true, &path);
    while (block_tree_path_get_key(&path)) {
        file.block_mac = block_tree_path_get_data_block_mac(&path);
        file_print(tr, &file);
        block_tree_path_next(&path);
    }
}

/**
 * file_check - Check the file block map for errors
 * @tr:         Transaction object.
 * @file:       File handle object.
 *
 * Return: %false if an unrecoverable error was detected in the file block map,
 * %true if the block map was consistent.
 */
bool file_check(struct transaction* tr,
                const struct storage_file_handle* file) {
    struct block_map block_map;
    data_block_t file_block_size = get_file_block_size(tr->fs);

    file_block_map_init(tr, &block_map, &file->block_mac);
    return block_map_check(tr, &block_map,
                           DIV_ROUND_UP(file->size, file_block_size));
}

/**
 * file_block_map_update - Update file entry with block_map or size changes
 * @tr:         Transaction object.
 * @block_map:  Block map object.
 * @file:       File handle object.
 *
 */
static void file_block_map_update(struct transaction* tr,
                                  struct block_map* block_map,
                                  const char* new_path,
                                  struct storage_file_handle* file) {
    bool found;
    data_block_t old_block;
    data_block_t file_block;
    data_block_t new_block;
    struct block_mac block_mac;
    const struct file_entry* file_entry_ro;
    struct file_entry* file_entry_rw = NULL;
    struct obj_ref file_entry_ref = OBJ_REF_INITIAL_VALUE(file_entry_ref);
    struct obj_ref file_entry_copy_ref = OBJ_REF_INITIAL_VALUE(file_entry_ref);
    struct block_tree_path tree_path;

    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        return;
    }

    assert(block_mac_valid(tr, &file->block_mac));

    file_entry_ro = block_get(tr, &file->block_mac, NULL, &file_entry_ref);
    if (!file_entry_ro) {
        assert(tr->failed);
        pr_warn("transaction failed, abort\n");
        return;
    }
    assert(file_entry_ro);
    found = file_tree_lookup(&block_mac, tr, &tr->files_added, &tree_path,
                             file_entry_ro->info.path, !!new_path);
    if (!found) {
        found = file_tree_lookup(&block_mac, tr, &tr->fs->files, &tree_path,
                                 file_entry_ro->info.path, false);
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            goto err;
        }
        assert(found);

        if (new_path) {
            block_tree_insert_block_mac(tr, &tr->files_removed,
                                        block_mac_to_block(tr, &block_mac),
                                        block_mac);
        }

        old_block = block_mac_to_block(tr, &block_mac);
        file_block = block_mac_to_block(tr, &file->block_mac);
        if (transaction_block_need_copy(tr, file_block)) {
            if (tr->failed) {
                pr_warn("transaction failed, abort\n");
                goto err;
            }
            assert((block_map && block_map->tree.root_block_changed) ||
                   file->size != file_entry_ro->info.size || new_path);
            assert(old_block == file_block);
            new_block = block_allocate(tr);
            if (tr->failed) {
                pr_warn("transaction failed, abort\n");
                goto err;
            }
            assert(new_block);
            block_mac_set_block(tr, &block_mac, new_block);

            pr_write("copy file block %" PRIu64 " -> %" PRIu64 "\n", file_block,
                     new_block);

            /*
             * Use block_get_copy instead of block_move since tr->fs->files
             * is still used and not updated until file_transaction_complete.
             */
            // TODO: fix
            file_entry_rw = block_get_copy(tr, file_entry_ro, new_block, false,
                                           &file_entry_copy_ref);
            block_put(file_entry_ro, &file_entry_ref);
            file_entry_ro = file_entry_rw;
            obj_ref_transfer(&file_entry_ref, &file_entry_copy_ref);
            if (tr->failed) {
                pr_warn("transaction failed, abort\n");
                goto err;
            }
            /* TODO: insert mac */
            block_tree_insert(tr, &tr->files_updated, file_block, new_block);
            block_free(tr, file_block);
            file->block_mac = block_mac;
        }
        assert(!file_tree_lookup(NULL, tr, &tr->files_added, &tree_path,
                                 file_entry_ro->info.path, false));

        /* TODO: get path from insert operation */
        block_tree_walk(tr, &tr->files_updated, old_block, false, &tree_path);
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            goto err;
        }
        assert(block_tree_path_get_key(&tree_path) == old_block);
        block_mac = block_tree_path_get_data_block_mac(&tree_path);
        assert(block_mac_to_block(tr, &block_mac) ==
               block_mac_to_block(tr, &file->block_mac));
        /* TODO: enable after insert mac TODO */
        // assert(block_mac_eq(tr, &block_mac, &file->block_mac));

        if (new_path) {
            /* TODO: remove by path or, when possible, skip insert instead */
            block_tree_remove(tr, &tr->files_updated, old_block,
                              block_mac_to_block(tr, &block_mac));
        }
    }
    if (!file_entry_rw) {
        file_entry_rw = block_dirty(tr, file_entry_ro, false);
    }

    if (block_map) {
        pr_write("file at %" PRIu64 ": update block_map %" PRIu64 " -> %" PRIu64
                 "\n",
                 block_mac_to_block(tr, &block_mac),
                 block_mac_to_block(tr, &file_entry_rw->block_map),
                 block_mac_to_block(tr, &block_map->tree.root));

        file_entry_rw->block_map = block_map->tree.root;
    }

    file_entry_rw->info.size = file->size;
    if (new_path) {
        strcpy(file_entry_rw->info.path, new_path);
        block_put_dirty(tr, file_entry_rw, &file_entry_ref, &block_mac, NULL);
        block_tree_insert_block_mac(tr, &tr->files_added,
                                    path_hash(tr, new_path), block_mac);
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            goto err;
        }
        block_mac_copy(tr, &file->block_mac, &block_mac);
    } else {
        block_tree_path_put_dirty(tr, &tree_path, tree_path.count,
                                  file_entry_rw, &file_entry_ref);
        /* TODO: add better api */
        file->block_mac = tree_path.entry[tree_path.count].block_mac;
    }

    /*
     * Move to head of list so opening the same file twice in a transaction
     * commits the changes to the file_handle that was modified. Writing to
     * both handles is not currently supported.
     */
    list_delete(&file->node);
    list_add_head(&tr->open_files, &file->node);

    return;

err:
    if (file_entry_rw) {
        block_put_dirty_discard(file_entry_rw, &file_entry_ref);
    } else {
        block_put(file_entry_ro, &file_entry_ref);
    }
}

/**
 * get_file_block_size - Get file data block size
 * @fs:         File system state object.
 *
 * Return: Get size of data block returned by file_get_block and
 * file_get_block_write for @fs.
 */
size_t get_file_block_size(struct fs* fs) {
    return fs->dev->block_size - sizeof(struct iv);
}

/**
 * file_get_block_etc - Helper function to get a file block for read or write
 * @tr:         Transaction object.
 * @file:       File handle object.
 * @file_block: File block number. 0 based.
 * @read:       %true if data should be read from disk, %false otherwise.
 * @write:      %true if returned data should be writeable, %false otherwise.
 * @ref:        Pointer to store reference in.
 *
 * Return: Const block data pointer, or NULL if no valid block is found at
 * @file_block or if @write is %true and a block could not be allocated.
 */
static const void* file_get_block_etc(struct transaction* tr,
                                      struct storage_file_handle* file,
                                      data_block_t file_block,
                                      bool read,
                                      bool write,
                                      struct obj_ref* ref) {
    bool found = false;
    const void* data = NULL;
    struct block_map block_map;
    struct block_mac block_mac;
    data_block_t old_disk_block;
    data_block_t new_block;
    bool dirty = false;

    if (tr->failed) {
        pr_warn("transaction failed, ignore\n");
        goto err;
    }

    file_block_map_init(tr, &block_map, &file->block_mac);
    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        goto err;
    }

    file->used_by_tr = true;

    found = block_map_get(tr, &block_map, file_block, &block_mac);
    if (found) {
        if (read) {
            data = block_get(tr, &block_mac, NULL, ref); /* TODO: pass iv? */
        } else {
            data = block_get_no_read(tr, block_mac_to_block(tr, &block_mac),
                                     ref);
        }
        /* TODO: handle mac mismatch better */
    }

    old_disk_block = found ? block_mac_to_block(tr, &block_mac) : 0;
    if (write && (!found || transaction_block_need_copy(tr, old_disk_block))) {
        new_block = block_allocate(tr);
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            goto err;
        }
        assert(new_block);
        block_mac_set_block(tr, &block_mac, new_block);

        if (found) {
            data = block_move(tr, data, new_block, false);
            dirty = true;
            assert(!tr->failed);
            block_free(tr, old_disk_block);
        } else {
            if (read) {
                assert(write);
                data = block_get_cleared(tr, new_block, false, ref);
                dirty = true;
            } else {
                data = block_get_no_read(tr, new_block, ref);
            }
        }
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            goto err;
        }
        /* TODO: get new mac */
        assert(!tr->failed);
        block_map_set(tr, &block_map, file_block, &block_mac);
        file_block_map_update(tr, &block_map, NULL, file);
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            goto err;
        }
    }
    if (write && !dirty) {
        data = block_dirty(tr, data, false);
    }
    if (!data) {
        return NULL;
    }
    return data + sizeof(struct iv);

err:
    if (dirty) {
        block_put_dirty_discard((void*)data, ref);
    } else if (data) {
        block_put(data, ref);
    }
    return NULL;
}

/**
 * file_get_block - Get a file block for read
 * @tr:         Transaction object.
 * @file:       File handle object.
 * @file_block: File block number. 0 based.
 * @ref:        Pointer to store reference in.
 *
 * Return: Const block data pointer, or NULL if no valid block is found at
 * @file_block.
 */
const void* file_get_block(struct transaction* tr,
                           struct storage_file_handle* file,
                           data_block_t file_block,
                           struct obj_ref* ref) {
    return file_get_block_etc(tr, file, file_block, true, false, ref);
}

/**
 * file_get_block_write - Helper function to get a file block for write
 * @tr:         Transaction object.
 * @file:       File handle object.
 * @file_block: File block number. 0 based.
 * @read:       %true if data should be read from disk, %false otherwise.
 * @ref:        Pointer to store reference in.
 *
 * Return: Block data pointer, or NULL if  a block could not be allocated.
 */
void* file_get_block_write(struct transaction* tr,
                           struct storage_file_handle* file,
                           data_block_t file_block,
                           bool read,
                           struct obj_ref* ref) {
    return (void*)file_get_block_etc(tr, file, file_block, read, true, ref);
}

/**
 * file_block_put - Release reference to a block returned by file_get_block
 * @data:       File block data pointer
 * @data_ref:   Reference pointer to release
 */
void file_block_put(const void* data, struct obj_ref* data_ref) {
    block_put(data - sizeof(struct iv), data_ref);
}

/**
 * file_block_put_dirty - Release reference to a dirty file block
 * @tr:         Transaction
 * @file:       File handle object.
 * @file_block: File block number. 0 based.
 * @data:       File block data pointer
 * @data_ref:   Reference pointer to release
 *
 * Release reference to a file block previously returned by
 * file_get_block_write, and update mac value in block_mac.
 */
void file_block_put_dirty(struct transaction* tr,
                          struct storage_file_handle* file,
                          data_block_t file_block,
                          void* data,
                          struct obj_ref* data_ref) {
    struct block_map block_map;

    file_block_map_init(tr, &block_map, &file->block_mac);

    block_map_put_dirty(tr, &block_map, file_block, data - sizeof(struct iv),
                        data_ref);

    file_block_map_update(tr, &block_map, NULL, file);
}

/**
 * file_get_info - Get a file informaion for read
 * @tr:         Transaction object.
 * @block_mac:  File entry block_mac.
 * @ref:        Pointer to store reference in.
 *
 * Return: Const file info pointer, or NULL if no valid block is found at
 * @block_mac.
 */
const struct file_info* file_get_info(struct transaction* tr,
                                      const struct block_mac* block_mac,
                                      struct obj_ref* ref) {
    const struct file_entry* file_entry;

    file_entry = block_get(tr, block_mac, NULL, ref);
    if (!file_entry) {
        assert(tr->failed);
        pr_warn("transaction failed, abort\n");
        return NULL;
    }
    assert(file_entry);
    assert(file_entry->magic == FILE_ENTRY_MAGIC);

    return &file_entry->info;
}

/**
 * file_info_put - Release reference to a block returned by file_get_info
 * @data:       File info data pointer
 * @data_ref:   Reference pointer to release
 */
void file_info_put(const struct file_info* data, struct obj_ref* data_ref) {
    const struct file_entry* entry = containerof(data, struct file_entry, info);
    assert(entry->magic == FILE_ENTRY_MAGIC);
    block_put(entry, data_ref);
}

/**
 * file_get_size - Get file size
 * @tr:         Transaction
 * @file:       File handle object.
 * @size:       Pointer to return size in.
 *
 * Return: %true if @size was set, %false if @size was not set because @file is
 * invalid or @tr has failed.
 */
bool file_get_size(struct transaction* tr,
                   struct storage_file_handle* file,
                   data_block_t* size) {
    if (tr->failed) {
        pr_warn("transaction failed, ignore\n");
        return false;
    }

    if (!block_mac_valid(tr, &file->block_mac)) {
        pr_warn("invalid file handle\n");
        return false;
    }

    file->used_by_tr = true;
    *size = file->size;

    return true;
}

/**
 * file_set_size - Set file size
 * @tr:         Transaction
 * @file:       File handle object.
 * @size:       New file size.
 *
 * Set file size and free blocks that are not longer needed. Does not clear any
 * partial block data.
 */
void file_set_size(struct transaction* tr,
                   struct storage_file_handle* file,
                   data_block_t size) {
    data_block_t file_block;
    struct block_map block_map;
    size_t file_block_size = get_file_block_size(tr->fs);

    if (tr->failed) {
        pr_warn("transaction failed, ignore\n");
        return;
    }

    file_block_map_init(tr, &block_map, &file->block_mac);
    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        return;
    }
    if (size == file->size) {
        return;
    }
    if (size < file->size) {
        file_block = DIV_ROUND_UP(size, file_block_size);
        block_map_truncate(tr, &block_map, file_block);
    }
    file->size = size;
    file_block_map_update(tr, &block_map, NULL, file);
}

/**
 * file_tree_lookup - Helper function to search for a file in a specific tree
 * @block_mac_out:  Block-mac object to return block number and mac in.
 * @tr:             Transaction object.
 * @tree:           Tree object.
 * @tree_path:      Tree path object.
 * @file_path:      File path string.
 * @remove:         %true if found entry should be removed, %false otherwise.
 *
 * Return: %true if @file_path was found in @tree, %false otherwise.
 */
static bool file_tree_lookup(struct block_mac* block_mac_out,
                             struct transaction* tr,
                             struct block_tree* tree,
                             struct block_tree_path* tree_path,
                             const char* file_path,
                             bool remove) {
    struct block_mac block_mac;
    data_block_t hash = path_hash(tr, file_path);
    const struct file_entry* file_entry;
    struct obj_ref file_entry_ref = OBJ_REF_INITIAL_VALUE(file_entry_ref);
    bool found = false;

    assert(strlen(file_path) < sizeof(file_entry->info.path));
    assert(sizeof(*file_entry) <= tr->fs->dev->block_size);

    block_tree_walk(tr, tree, hash - 1, false, tree_path);
    while (block_tree_path_get_key(tree_path) &&
           block_tree_path_get_key(tree_path) < hash) {
        block_tree_path_next(tree_path);
    }
    while (block_tree_path_get_key(tree_path) == hash) {
        block_mac = block_tree_path_get_data_block_mac(tree_path);
        if (!block_mac_to_block(tr, &block_mac)) {
            if (LOCAL_TRACE >= TRACE_LEVEL_WARNING) {
                pr_warn("got 0 block pointer for hash %" PRIu64
                        " while looking for %s, hash 0x%" PRIx64 "\n",
                        block_tree_path_get_key(tree_path), file_path, hash);
                block_tree_print(tr, tree);
            }
            block_tree_path_next(tree_path);
            block_mac = block_tree_path_get_data_block_mac(tree_path);
            pr_warn("next %" PRIu64 ", hash 0x%" PRIx64 "\n",
                    block_mac_to_block(tr, &block_mac),
                    block_tree_path_get_key(tree_path));
        }
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            return false;
        }
        assert(block_mac_to_block(tr, &block_mac));
        file_entry = block_get(tr, &block_mac, NULL, &file_entry_ref);
        if (!file_entry) {
            assert(tr->failed);
            pr_warn("transaction failed, abort\n");
            return false;
        }
        assert(file_entry);
        assert(file_entry->magic == FILE_ENTRY_MAGIC);
        found = !strcmp(file_path, file_entry->info.path);

        pr_read("block %" PRIu64 ", hash 0x%" PRIx64 " match, found %d\n",
                block_mac_to_block(tr, &block_mac), hash, found);

        block_put(file_entry, &file_entry_ref);
        if (found) {
            if (remove) {
                /* TODO: remove by path */
                // block_tree_remove_path(tr, tree_path);
                /* TODO: pass mac */
                block_tree_remove(tr, tree, hash,
                                  block_mac_to_block(tr, &block_mac));
            }
            *block_mac_out = block_mac;
            return true;
        }
        block_tree_path_next(tree_path);
    }
    if (LOCAL_TRACE >= TRACE_LEVEL_READ) {
        pr_read("%s: hash 0x%" PRIx64 " does not match 0x%" PRIx64 "\n",
                __func__, hash, block_tree_path_get_key(tree_path));
        block_tree_print(tr, tree);
    }
    return false;
}

/**
 * file_create - Helper function to create a new file
 * @block_mac_out:  Block-mac object to return block number and mac in.
 * @tr:             Transaction object.
 * @path:           File path string.
 *
 * Create a new file and insert it into &tr->files_added. Caller must make
 * a file matching @path does not already exist.
 *
 * Return: %true if file was created, %false otherwise.
 */
static bool file_create(struct block_mac* block_mac_out,
                        struct transaction* tr,
                        const char* path) {
    data_block_t block;
    struct file_entry* file_entry;
    struct obj_ref file_entry_ref = OBJ_REF_INITIAL_VALUE(file_entry_ref);
    data_block_t hash;

    hash = path_hash(tr, path);

    block = block_allocate(tr);

    pr_write("create file, %s, hash 0x%" PRIx64 ", at block %" PRIu64 "\n",
             path, hash, block);

    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        goto err;
    }

    assert(block);
    block_mac_set_block(tr, block_mac_out, block);

    file_entry = block_get_cleared(tr, block, false, &file_entry_ref);
    assert(file_entry);
    file_entry->magic = FILE_ENTRY_MAGIC;
    strcpy(file_entry->info.path, path);
    block_put_dirty(tr, file_entry, &file_entry_ref, block_mac_out, NULL);
    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        goto err;
    }
    block_tree_insert_block_mac(tr, &tr->files_added, hash, *block_mac_out);
    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        goto err;
    }
    return true;

err:
    return false;
}

/**
 * file_is_removed - Helper function to check if transaction deletes file
 * @tr:         Transaction object.
 * @block:      Block number for file.
 *
 * Return: %true if file is removed in @tr, %false otherwise.
 */
static bool file_is_removed(struct transaction* tr, data_block_t block) {
    struct block_tree_path tree_path;

    block_tree_walk(tr, &tr->files_removed, block, false, &tree_path);

    return block_tree_path_get_key(&tree_path) == block;
}

/**
 * file_check_updated - Helper function to check if transaction updated file
 * @tr:                     Transaction object.
 * @committed_block_mac:    Block-mac object to check.
 * @block_mac_out:          Block-mac object to return block number and mac in
 *                          for the current state of the file in @tr.
 *
 * Return: %true if file is updated in @tr, %false otherwise.
 */
static bool file_check_updated(struct transaction* tr,
                               const struct block_mac* committed_block_mac,
                               struct block_mac* block_mac_out) {
    struct block_tree_path tree_path;
    data_block_t block = block_mac_to_block(tr, committed_block_mac);

    block_tree_walk(tr, &tr->files_updated, block, false, &tree_path);
    if (block_tree_path_get_key(&tree_path) == block) {
        pr_read("%" PRIu64
                ", already updated in this transaction, use new copy %" PRIu64
                "\n",
                block, block_tree_path_get_data(&tree_path));
        *block_mac_out = block_tree_path_get_data_block_mac(&tree_path);
        return true;
    }

    return false;
}

/**
 * file_lookup_not_removed - Helper function to search for a file
 * @block_mac_out:              Block-mac object to return block number and mac
 *                              in for the current state of the file.
 * @committed_block_mac_out:    Block-mac object to return block number and mac
 *                              in for the committed state of the file.
 * @tr:                         Transaction object.
 * @tree_path:                  Tree path object.
 * @file_path:                  File path string.
 *
 * Helper function to search for a file that existed before @tr was activated.
 *
 * Return: %true if @file_path was found in @tr->fs->files but not found in
 * @tr->files_removed, %false otherwise.
 */
static bool file_lookup_not_removed(struct block_mac* block_mac_out,
                                    struct block_mac* committed_block_mac_out,
                                    struct transaction* tr,
                                    struct block_tree_path* tree_path,
                                    const char* file_path) {
    bool found;
    struct block_mac block_mac;

    found = file_tree_lookup(&block_mac, tr, &tr->fs->files, tree_path,
                             file_path, false);
    if (!found || file_is_removed(tr, block_mac_to_block(tr, &block_mac))) {
        if (found) {
            pr_read("file %s, %" PRIu64 " in removed\n", file_path,
                    block_mac_to_block(tr, &block_mac));
        } else {
            pr_read("file %s not in tr->fs->files\n", file_path);
        }
        return false;
    }
    *committed_block_mac_out = block_mac;

    block_tree_walk(tr, &tr->files_updated, block_mac_to_block(tr, &block_mac),
                    false, tree_path);
    if (block_tree_path_get_key(tree_path) ==
        block_mac_to_block(tr, &block_mac)) {
        pr_read("file %s, %" PRIu64
                ", already updated in this transaction, use new copy %" PRIu64
                "\n",
                file_path, block_mac_to_block(tr, &block_mac),
                block_tree_path_get_data(tree_path));
        block_mac = block_tree_path_get_data_block_mac(tree_path);
    }
    pr_read("file %s, %" PRIu64 ", found in tr->fs->files\n", file_path,
            block_mac_to_block(tr, &block_mac));

    /*
     * TODO: mark file (or blocks) in_use so other writers to the same file
     * will cause this transaction to fail. Currently conflicts are only
     * detected after each transaction writes to the file.
     */

    *block_mac_out = block_mac;
    return true;
}

/**
 * file_find_open - Check if transaction has file open and return it
 * @tr:         Transaction object.
 * @block_mac:  Current block and mac value for open file.
 *
 * Return: file handle of open file if file is open in @tr, NULL otherwise.
 */
static struct storage_file_handle* file_find_open(
        struct transaction* tr,
        const struct block_mac* block_mac) {
    struct storage_file_handle* file;

    list_for_every_entry(&tr->open_files, file, struct storage_file_handle,
                         node) {
        if (block_mac_same_block(tr, &file->block_mac, block_mac)) {
            return file;
        }
    }

    return NULL;
}

/**
 * file_iterate - Iterate over all files
 * @tr:         Transaction object.
 * @start_path: First file to not iterate over.
 * @added:      %false to iterate over committed files, %true to iterate over
 *              uncommitted files added by @tr.
 * @state:      client state object containing function to call for each file.
 * @allow_repaired: Accept a repaired file system state.
 *
 * Return: %FILE_OP_ERR_FS_REPAIRED if the file system has been repaired and
 * @allow_repaired was false, %FILE_OP_ERR_FAILED if the file system is not
 * readable or an internal error occurred, and %FILE_OP_SUCCESS otherwise.
 */
enum file_op_result file_iterate(struct transaction* tr,
                                 const char* start_path,
                                 bool added,
                                 struct file_iterate_state* state,
                                 bool allow_repaired) {
    struct block_tree_path tree_path;
    struct block_mac block_mac;
    struct block_tree* tree = added ? &tr->files_added : &tr->fs->files;
    bool found;
    bool stop;
    bool removed = false;

    assert(tr->fs);
    if (!fs_is_readable(tr->fs)) {
        return FILE_OP_ERR_FAILED;
    }
    if (!allow_repaired && (tr->repaired || fs_is_repaired(tr->fs))) {
        return FILE_OP_ERR_FS_REPAIRED;
    }

    if (start_path == NULL) {
        block_tree_walk(tr, tree, 0, true, &tree_path);
    } else {
        found = file_tree_lookup(&block_mac, tr, tree, &tree_path, start_path,
                                 false);
        if (!found) {
            return FILE_OP_ERR_FAILED;
        }
        block_tree_path_next(&tree_path);
    }
    if (tr->failed) {
        return FILE_OP_ERR_FAILED;
    }

    while (block_tree_path_get_key(&tree_path)) {
        block_mac = block_tree_path_get_data_block_mac(&tree_path);
        if (!added) {
            removed = file_is_removed(tr, block_mac_to_block(tr, &block_mac));
            file_check_updated(tr, &block_mac, &block_mac);
        }
        if (tr->failed) {
            return FILE_OP_ERR_FAILED;
        }

        stop = state->file(state, tr, &block_mac, added, removed);
        if (stop) {
            return FILE_OP_SUCCESS;
        }
        block_tree_path_next(&tree_path);
    }
    return FILE_OP_SUCCESS;
}

/**
 * file_open - Open file
 * @tr:         Transaction object.
 * @path:       Path to find or create file at.
 * @file:       File handle object.
 * @create:     FILE_OPEN_NO_CREATE, FILE_OPEN_CREATE or
 *              FILE_OPEN_CREATE_EXCLUSIVE.
 * @allow_repaired: Accept a repaired file system state. If the file system has
 *                  been repaired, missing files may have previously existed and
 *                  are now rolled back.
 *
 * Return: %FILE_OP_ERR_FS_REPAIRED if the file system has been repaired and
 * @allow_repaired was false, &enum file_op_result.FILE_OP_SUCCESS if file was
 * opened, or an error describing the failure to open the file.
 */
enum file_op_result file_open(struct transaction* tr,
                              const char* path,
                              struct storage_file_handle* file,
                              enum file_create_mode create,
                              bool allow_repaired) {
    bool found;
    struct block_mac block_mac;
    struct block_mac committed_block_mac =
            BLOCK_MAC_INITIAL_VALUE(committed_block_mac);
    struct block_tree_path tree_path;
    const struct file_entry* file_entry_ro;
    struct obj_ref file_entry_ref = OBJ_REF_INITIAL_VALUE(file_entry_ref);

    assert(tr->fs);
    if (!allow_repaired && (tr->repaired || fs_is_repaired(tr->fs))) {
        return FILE_OP_ERR_FS_REPAIRED;
    }

    if (!fs_is_readable(tr->fs)) {
        return FILE_OP_ERR_FAILED;
    }

    found = file_tree_lookup(&block_mac, tr, &tr->files_added, &tree_path, path,
                             false);
    if (found) {
        goto found;
    }

    found = file_lookup_not_removed(&block_mac, &committed_block_mac, tr,
                                    &tree_path, path);
    if (found) {
        goto found;
    }
    if (tr->failed) {
        return FILE_OP_ERR_FAILED;
    }

    if (create != FILE_OPEN_NO_CREATE) {
        found = file_create(&block_mac, tr, path);
    }
    if (found) {
        goto created;
    }
    if (tr->failed) {
        return FILE_OP_ERR_FAILED;
    } else {
        return FILE_OP_ERR_NOT_FOUND;
    }

found:
    if (create == FILE_OPEN_CREATE_EXCLUSIVE) {
        return FILE_OP_ERR_EXIST;
    }
    if (file_find_open(tr, &block_mac)) {
        pr_warn("%s already open\n", path);
        return FILE_OP_ERR_ALREADY_OPEN;
    }
created:
    file_entry_ro = block_get(tr, &block_mac, NULL, &file_entry_ref);
    if (!file_entry_ro) {
        assert(tr->failed);
        pr_warn("transaction failed, abort\n");
        return FILE_OP_ERR_FAILED;
    }
    assert(file_entry_ro);
    list_add_head(&tr->open_files, &file->node);
    file->to_commit_block_mac = committed_block_mac;
    file->committed_block_mac = committed_block_mac;
    file->block_mac = block_mac;
    file->size = file_entry_ro->info.size;
    file->used_by_tr = false;
    block_put(file_entry_ro, &file_entry_ref);

    return FILE_OP_SUCCESS;
}

/**
 * file_close - Close file
 * @file:       File handle object.
 *
 * Must be called before freeing @file after a successful file_open call.
 */
void file_close(struct storage_file_handle* file) {
    list_delete(&file->node);
}

/**
 * file_delete - Delete file
 * @tr:         Transaction object.
 * @path:       Path to find file at.
 * @allow_repaired: Accept a repaired file system state.
 *
 * Return: %FILE_OP_ERR_FS_REPAIRED if the file system has been repaired and
 * @allow_repaired was false, %FILE_OP_SUCCESS if the file existed and was
 * deleted, %FILE_OP_ERR_NOT_FOUND if the file did not exist, and
 * %FILE_OP_ERR_FAILED if some other error occurred.
 */
enum file_op_result file_delete(struct transaction* tr,
                                const char* path,
                                bool allow_repaired) {
    bool found;
    struct block_mac block_mac;
    struct block_mac old_block_mac;
    bool in_files = false;
    const struct file_entry* file_entry;
    struct obj_ref file_entry_ref = OBJ_REF_INITIAL_VALUE(file_entry_ref);
    struct block_map block_map = BLOCK_MAP_INITIAL_VALUE(block_map);
    struct block_tree_path tree_path;
    struct storage_file_handle* open_file;

    assert(tr->fs);
    if (!fs_is_readable(tr->fs)) {
        return FILE_OP_ERR_FAILED;
    }
    if (!allow_repaired && (tr->repaired || fs_is_repaired(tr->fs))) {
        return FILE_OP_ERR_FS_REPAIRED;
    }

    found = file_tree_lookup(&block_mac, tr, &tr->files_added, &tree_path, path,
                             true);
    if (!found) {
        pr_read("file %s not in tr->files_added\n", path);
        found = file_lookup_not_removed(&block_mac, &old_block_mac, tr,
                                        &tree_path, path);
        if (!found) {
            pr_warn("file %s not found\n", path);
            return tr->failed ? FILE_OP_ERR_FAILED : FILE_OP_ERR_NOT_FOUND;
        }
        in_files = true;
    }

    pr_write("delete file, %s, at block %" PRIu64 "\n", path,
             block_mac_to_block(tr, &block_mac));

    file_entry = block_get(tr, &block_mac, NULL, &file_entry_ref);
    if (!file_entry) {
        assert(tr->failed);
        pr_warn("transaction failed, abort\n");
        return FILE_OP_ERR_FAILED;
    }
    assert(file_entry);
    assert(!strcmp(file_entry->info.path, path));
    block_map_init(tr, &block_map, &file_entry->block_map,
                   tr->fs->dev->block_size);
    if (!in_files || !block_mac_same_block(tr, &block_mac, &old_block_mac)) {
        block_discard_dirty(file_entry);
    }
    block_put(file_entry, &file_entry_ref);
    if (in_files) {
        if (!block_mac_same_block(tr, &block_mac, &old_block_mac)) {
            /* TODO: pass mac */
            block_tree_remove(tr, &tr->files_updated,
                              block_mac_to_block(tr, &old_block_mac),
                              block_mac_to_block(tr, &block_mac));
            if (tr->failed) {
                pr_warn("transaction failed, abort\n");
                return FILE_OP_ERR_FAILED;
            }
        }
        block_tree_insert_block_mac(tr, &tr->files_removed,
                                    block_mac_to_block(tr, &old_block_mac),
                                    old_block_mac);
    }
    block_free(tr, block_mac_to_block(tr, &block_mac));
    block_map_free(tr, &block_map);

    open_file = file_find_open(tr, &block_mac);
    if (open_file) {
        struct block_mac clear = BLOCK_MAC_INITIAL_VALUE(clear);
        open_file->block_mac = clear;
        open_file->size = 0;
    }
    return FILE_OP_SUCCESS;
}

/**
 * file_move - Move a file to a new path, optionally replacing an existing file
 * @tr:             Transaction object.
 * @file:           File handle object.
 * @dest_path:      Path to move file to.
 * @dest_create:    FILE_OPEN_NO_CREATE, FILE_OPEN_CREATE or
 *                  FILE_OPEN_CREATE_EXCLUSIVE.
 * @allow_repaired: Accept a repaired file system state.
 *
 * Return: %FILE_OP_SUCCESS if the operation was successful,
 * %FILE_OP_ERR_FS_REPAIRED if the file system has been repaired and
 * @allow_repaired was false, %FILE_OP_ERR_EXIST if the destination file already
 * exists and %FILE_OPEN_CREATE_EXCLUSIVE was requested, %FILE_OP_ERR_NOT_FOUND
 * if the destination file did not exist but %FILE_OPEN_NO_CREATE was required,
 * and %FILE_OP_ERR_FAILED if some other error occurred.
 */
enum file_op_result file_move(struct transaction* tr,
                              struct storage_file_handle* file,
                              const char* dest_path,
                              enum file_create_mode dest_create,
                              bool allow_repaired) {
    assert(tr->fs);
    struct block_mac block_mac;
    struct block_mac committed_block_mac;
    struct block_tree_path tree_path;
    bool dest_found;

    if (!fs_is_readable(tr->fs)) {
        return FILE_OP_ERR_FAILED;
    }
    if (!allow_repaired && (tr->repaired || fs_is_repaired(tr->fs))) {
        return FILE_OP_ERR_FS_REPAIRED;
    }

    dest_found = file_tree_lookup(&block_mac, tr, &tr->files_added, &tree_path,
                                  dest_path, false);
    if (!dest_found) {
        dest_found = file_lookup_not_removed(&block_mac, &committed_block_mac,
                                             tr, &tree_path, dest_path);
    }
    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        return FILE_OP_ERR_FAILED;
    }

    if (dest_found) {
        if (dest_create == FILE_OPEN_CREATE_EXCLUSIVE) {
            return FILE_OP_ERR_EXIST;
        }
        if (block_mac_eq(tr, &file->block_mac, &block_mac)) {
            return FILE_OP_SUCCESS;
        }
        file_delete(tr, dest_path, allow_repaired);
    } else {
        if (dest_create == FILE_OPEN_NO_CREATE) {
            return FILE_OP_ERR_NOT_FOUND;
        }
    }

    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        return FILE_OP_ERR_FAILED;
    }
    file_block_map_update(tr, NULL, dest_path, file);
    if (tr->failed) {
        pr_warn("transaction failed, abort\n");
        return FILE_OP_ERR_FAILED;
    }
    return FILE_OP_SUCCESS;
}

/**
 * file_for_each_open - Call function for every open file in every transaction
 * @tr:         Transaction object.
 * @func:       Function to call.
 */
static void file_for_each_open(struct transaction* tr,
                               void (*func)(struct transaction* tr,
                                            struct transaction* file_tr,
                                            struct storage_file_handle* file)) {
    struct transaction* tmp_tr;
    struct transaction* other_tr;
    struct storage_file_handle* file;

    list_for_every_entry_safe(&tr->fs->transactions, other_tr, tmp_tr,
                              struct transaction, node) {
        list_for_every_entry(&other_tr->open_files, file,
                             struct storage_file_handle, node) {
            func(tr, other_tr, file);
        }
    }
}

/**
 * file_restore_to_commit - Restore to_commit state to commited state
 * @tr:         Current transaction.
 * @file_tr:    Transaction that @file was found in.
 * @file:       File handle object.
 */
static void file_restore_to_commit(struct transaction* tr,
                                   struct transaction* file_tr,
                                   struct storage_file_handle* file) {
    struct block_mac* src = &file->committed_block_mac;
    struct block_mac* dest = &file->to_commit_block_mac;
    if (block_mac_same_block(tr, src, dest)) {
        assert(block_mac_eq(tr, src, dest));
        return;
    }
    pr_write("abort block %" PRIu64 "/%" PRIu64 " -> %" PRIu64 ", size %" PRIu64
             " -> %" PRIu64 "\n",
             block_mac_to_block(tr, &file->committed_block_mac),
             block_mac_to_block(tr, &file->block_mac),
             block_mac_to_block(tr, &file->to_commit_block_mac), file->size,
             file->to_commit_size);
    block_mac_copy(tr, dest, src);
}

/**
 * file_apply_to_commit - Apply to_commit state
 * @tr:         Current transaction.
 * @file_tr:    Transaction that @file was found in.
 * @file:       File handle object.
 *
 * Copies to_commit to commited and current state and fails conflicting
 * transactions.
 */
static void file_apply_to_commit(struct transaction* tr,
                                 struct transaction* file_tr,
                                 struct storage_file_handle* file) {
    struct block_mac* src = &file->to_commit_block_mac;
    struct block_mac* dest = &file->committed_block_mac;

    if (tr == file_tr) {
        file->used_by_tr = false;
    }

    if (block_mac_same_block(tr, src, dest)) {
        assert(block_mac_eq(tr, src, dest));
        pr_write("file handle %p, unchanged file at %" PRIu64 "\n", file,
                 block_mac_to_block(tr, &file->committed_block_mac));
        return;
    }

    if (file_tr != tr) {
        if (file->used_by_tr) {
            pr_warn("conflict %" PRIu64 " != %" PRIu64 " || used_by_tr %d\n",
                    block_mac_to_block(tr, &file->committed_block_mac),
                    block_mac_to_block(tr, &file->block_mac), file->used_by_tr);
            assert(!file_tr->failed);
            transaction_fail(file_tr);
        }
        assert(block_mac_same_block(tr, dest, &file->block_mac));
    }

    pr_write("file handle %p, apply block %" PRIu64 "/%" PRIu64 " -> %" PRIu64
             ", size %" PRIu64 " -> %" PRIu64 "\n",
             file, block_mac_to_block(tr, &file->committed_block_mac),
             block_mac_to_block(tr, &file->block_mac),
             block_mac_to_block(tr, &file->to_commit_block_mac), file->size,
             file->to_commit_size);

    block_mac_copy(tr, dest, src);
    if (tr == file_tr) {
        assert(block_mac_eq(tr, &file->block_mac, src));
        assert(file->size == file->to_commit_size);
    } else {
        block_mac_copy(tr, &file->block_mac, src);
        file->size = file->to_commit_size;
    }
}

/**
 * file_transaction_complete_failed - Restore open files state
 * @tr:                     Transaction object.
 *
 * Revert open file changes done by file_transaction_complete.
 */
void file_transaction_complete_failed(struct transaction* tr) {
    file_for_each_open(tr, file_restore_to_commit);
}

/**
 * file_update_block_mac_tr - Update open files with committed changes
 * @tr:                 Current transaction object.
 * @other_tr:           Transaction object to find files in.
 * @old_block_mac:      Block and mac of committed file.
 * @old_block_no_mac:   %true if @old_block_mac->max is invalid.
 * @new_block_mac:      New block and mac.
 * @new_size:           New size.
 *
 * Prepare update of open files referring to the file at @old_block_mac.
 */
static void file_update_block_mac_tr(struct transaction* tr,
                                     struct transaction* other_tr,
                                     const struct block_mac* old_block_mac,
                                     bool old_block_no_mac,
                                     const struct block_mac* new_block_mac,
                                     data_block_t new_size) {
    struct storage_file_handle* file;

    assert(block_mac_valid(tr, old_block_mac) || other_tr == tr);
    list_for_every_entry(&other_tr->open_files, file,
                         struct storage_file_handle, node) {
        if (block_mac_valid(tr, old_block_mac)
                    ? !block_mac_same_block(tr, &file->committed_block_mac,
                                            old_block_mac)
                    : !block_mac_same_block(tr, &file->block_mac,
                                            new_block_mac)) {
            pr_write("file handle %p, unrelated %" PRIu64 " != %" PRIu64 "\n",
                     file, block_mac_to_block(tr, &file->committed_block_mac),
                     block_mac_to_block(tr, new_block_mac));
            continue; /*unrelated file */
        }
        assert(old_block_no_mac || !block_mac_valid(tr, old_block_mac) ||
               block_mac_eq(tr, &file->committed_block_mac, old_block_mac));

        pr_write("file handle %p, stage block %" PRIu64 "/%" PRIu64
                 " -> %" PRIu64 ", size %" PRIu64 " -> %" PRIu64 "\n",
                 file, block_mac_to_block(tr, &file->committed_block_mac),
                 block_mac_to_block(tr, &file->block_mac),
                 block_mac_to_block(tr, new_block_mac), file->size, new_size);

        block_mac_copy(tr, &file->to_commit_block_mac, new_block_mac);
        file->to_commit_size = new_size;
    }
}

/**
 * file_update_block_mac_all - Update open files with committed changes
 * @tr:                 Transaction object.
 * @old_block_mac:      Block and mac of committed file.
 * @old_block_no_mac:   %true if @old_block_mac->max is invalid.
 * @new_block_mac:      New block and mac.
 * @new_size:           New size.
 *
 * Update other open files referring to the same file as @src_file with the
 * size, block and mac from @src_file.
 */
static void file_update_block_mac_all(struct transaction* tr,
                                      const struct block_mac* old_block_mac,
                                      bool old_block_no_mac,
                                      const struct block_mac* new_block_mac,
                                      data_block_t new_size) {
    struct transaction* tmp_tr;
    struct transaction* other_tr;

    list_for_every_entry_safe(&tr->fs->transactions, other_tr, tmp_tr,
                              struct transaction, node) {
        file_update_block_mac_tr(tr, other_tr, old_block_mac, old_block_no_mac,
                                 new_block_mac, new_size);
    }
}

/**
 * file_transaction_complete - Update files
 * @tr:                     Transaction object.
 * @new_files_block_mac:    Object to return block and mac of updated file tree
 *
 * Create a copy of @tr->fs->files and apply all file updates from @tr to it.
 * Called by transaction_complete, which will update the super-block and
 * @tr->fs->files if the transaction succeeds.
 */
void file_transaction_complete(struct transaction* tr,
                               struct block_mac* new_files_block_mac) {
    bool found;
    const struct file_entry* file_entry_ro;
    struct obj_ref file_entry_ref = OBJ_REF_INITIAL_VALUE(file_entry_ref);
    struct block_tree_path tree_path;
    struct block_tree_path tmp_tree_path;
    struct block_mac old_file;
    struct block_mac file;
    struct block_tree new_files;
    data_block_t hash;
    const struct block_mac clear_block_mac = BLOCK_MAC_INITIAL_VALUE(clear);

    block_tree_copy(&new_files, &tr->fs->files);

    block_tree_walk(tr, &tr->files_updated, 0, true, &tree_path);
    while (true) {
        file = block_tree_path_get_data_block_mac(&tree_path);
        if (!block_mac_to_block(tr, &file)) {
            break;
        }
        file_entry_ro = block_get(tr, &file, NULL, &file_entry_ref);
        if (!file_entry_ro) {
            assert(tr->failed);
            pr_warn("transaction failed, abort\n");
            return;
        }
        assert(file_entry_ro);
        block_mac_set_block(tr, &old_file, block_tree_path_get_key(&tree_path));

        pr_write("update file at %" PRIu64 " -> %" PRIu64 ", %s\n",
                 block_mac_to_block(tr, &old_file),
                 block_mac_to_block(tr, &file), file_entry_ro->info.path);

        file_update_block_mac_all(tr, &old_file, true, &file,
                                  file_entry_ro->info.size);

        hash = path_hash(tr, file_entry_ro->info.path);

        block_put(file_entry_ro, &file_entry_ref);

        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            return;
        }

        block_tree_update_block_mac(tr, &new_files, hash, old_file, hash, file);

        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            return;
        }

        assert(block_mac_to_block(tr, &old_file) !=
               block_mac_to_block(tr, &file));
        block_tree_path_next(&tree_path);
    }

    block_tree_walk(tr, &tr->files_removed, 0, true, &tree_path);
    while (true) {
        file = block_tree_path_get_data_block_mac(&tree_path);
        if (!block_mac_to_block(tr, &file)) {
            break;
        }
        file_entry_ro = block_get(tr, &file, NULL, &file_entry_ref);
        if (!file_entry_ro) {
            assert(tr->failed);
            pr_warn("transaction failed, abort\n");
            return;
        }
        assert(file_entry_ro);

        pr_write("delete file at %" PRIu64 ", %s\n",
                 block_mac_to_block(tr, &file), file_entry_ro->info.path);

        file_update_block_mac_all(tr, &file, false, &clear_block_mac, 0);

        found = file_tree_lookup(&old_file, tr, &new_files, &tmp_tree_path,
                                 file_entry_ro->info.path, true);
        block_put(file_entry_ro, &file_entry_ref);

        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            return;
        }

        assert(found);
        assert(block_mac_to_block(tr, &old_file) ==
               block_mac_to_block(tr, &file));
        block_tree_path_next(&tree_path);
    }
    block_tree_walk(tr, &tr->files_added, 0, true, &tree_path);
    while (true) {
        file = block_tree_path_get_data_block_mac(&tree_path);
        if (!block_mac_valid(tr, &file)) {
            break;
        }
        file_entry_ro = block_get(tr, &file, NULL, &file_entry_ref);
        if (!file_entry_ro) {
            assert(tr->failed);
            pr_warn("transaction failed, abort\n");
            return;
        }
        assert(file_entry_ro);
        pr_write("add file at %" PRIu64 ", %s\n", block_mac_to_block(tr, &file),
                 file_entry_ro->info.path);

        if (file_tree_lookup(&old_file, tr, &new_files, &tmp_tree_path,
                             file_entry_ro->info.path, false)) {
            block_put(file_entry_ro, &file_entry_ref);
            pr_err("add file at %" PRIu64
                   ", %s, failed, conflicts with %" PRIu64 "\n",
                   block_mac_to_block(tr, &file), file_entry_ro->info.path,
                   block_mac_to_block(tr, &old_file));
            transaction_fail(tr);
            return;
        }

        file_update_block_mac_tr(tr, tr, &clear_block_mac, false, &file,
                                 file_entry_ro->info.size);

        hash = path_hash(tr, file_entry_ro->info.path);
        block_put(file_entry_ro, &file_entry_ref);

        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            return;
        }

        block_tree_insert_block_mac(tr, &new_files, hash, file);
        if (tr->failed) {
            pr_warn("transaction failed, abort\n");
            return;
        }

        block_tree_path_next(&tree_path);
    }
    *new_files_block_mac = new_files.root;
}

/**
 * transaction_changed_file - Check if file was modified by current transaction
 * @tr:         Transaction object.
 * @file:       File handle.
 *
 * Return: %true if @file was modified by @tr, %false otherwise.
 */
static bool transaction_changed_file(struct transaction* tr,
                                     struct storage_file_handle* file) {
    return !block_mac_same_block(tr, &file->committed_block_mac,
                                 &file->block_mac);
}

/**
 * file_transaction_success - Update all file handles modified by transaction
 * @tr:         Transaction object.
 */
void file_transaction_success(struct transaction* tr) {
    file_for_each_open(tr, file_apply_to_commit);
}

/**
 * file_read_size - Read file entry to get file size
 * @tr:         Transaction object.
 * @block_mac:  Block and mac of file entry to read.
 * @sz:         Pointer to store file size in.
 *
 * Return: %true if @sz was set, %false otherwise.
 */
static bool file_read_size(struct transaction* tr,
                           const struct block_mac* block_mac,
                           data_block_t* sz) {
    const struct file_entry* file_entry_ro;
    struct obj_ref ref = OBJ_REF_INITIAL_VALUE(ref);

    if (!block_mac_valid(tr, block_mac)) {
        *sz = 0;
        return true;
    }

    file_entry_ro = block_get_no_tr_fail(tr, block_mac, NULL, &ref);
    if (!file_entry_ro) {
        return false;
    }
    *sz = file_entry_ro->info.size;
    block_put(file_entry_ro, &ref);
    return true;
}

/**
 * file_transaction_failed - Restore file handles after failed transaction
 * @tr:         Transaction object.
 *
 * Revert all file handles modified by @tr to the state of the files before @tr
 * was activeted. File handles for files crreated by @tr become invalid.
 */
void file_transaction_failed(struct transaction* tr) {
    struct storage_file_handle* file;
    bool success;

    list_for_every_entry(&tr->open_files, file, struct storage_file_handle,
                         node) {
        file->used_by_tr = false;
        if (transaction_changed_file(tr, file)) {
            file->block_mac = file->committed_block_mac;
            success = file_read_size(tr, &file->block_mac, &file->size);
            if (!success) {
                pr_warn("failed to read block %" PRIu64 ", clear file handle\n",
                        block_mac_to_block(tr, &file->block_mac));
                block_mac_clear(tr, &file->block_mac);
                block_mac_clear(tr, &file->committed_block_mac);
                file->size = 0;
            }
        }
    }
}

/**
 * file_rebuild_free_set - Remove a file's blocks from the input set
 * @tr:             Transaction object
 * @new_free_set:   Free set to modify
 * @file:           File handle whose blocks should be removed from
 *                  @new_free_set
 *
 * Update @new_free_set by removing from it all blocks referenced by @file, i.e.
 * the file metadata block, file block map nodes, and file data blocks. Caller
 * must ensure that @new_free_set contained all these referenced blocks before
 * calling this function.
 */
static void file_rebuild_free_set(struct transaction* tr,
                                  struct block_set* new_free_set,
                                  struct storage_file_handle* file) {
    struct block_map block_map;
    data_block_t block;
    struct block_tree_path path;
    int i;

    block_set_remove_block(tr, new_free_set,
                           block_mac_to_block(tr, &file->block_mac));

    file_block_map_init(tr, &block_map, &file->block_mac);
    block_tree_walk(tr, &block_map.tree, 0, true, &path);
    while (block_tree_path_get_key(&path)) {
        /*
         * We only remove a tree node the first time we see it. Because we walk
         * the tree in order, the first time we see a node we will visit its
         * lowest child i.e. path.entry[i].index == 0. When index > 0 we have
         * already visited and removed all parent nodes.
         */
        for (i = path.count - 1; i >= 0 && path.entry[i].index == 0; i--) {
            block = block_mac_to_block(tr, &path.entry[i].block_mac);
            block_set_remove_block(tr, new_free_set, block);
        }
        block_set_remove_block(tr, new_free_set,
                               block_tree_path_get_data(&path));
        block_tree_path_next(&path);
    }
}

/**
 * files_rebuild_free_set - Rebuild a free set from the files tree
 * @tr:             Transaction object
 * @new_free_set:   Free set to modify
 * @files_root:     Root block and mac of the files tree
 *
 * Update @new_free_set by removing from it all blocks referenced in the file
 * tree rooted at @files_root, i.e. all files tree nodes, file metadata blocks,
 * file block map nodes, and file data blocks. Caller must ensure that
 * @new_free_set contained all these referenced blocks before calling this
 * function.
 */
void files_rebuild_free_set(struct transaction* tr,
                            struct block_set* new_free_set,
                            struct block_mac* files_root) {
    struct block_tree files;
    data_block_t block;
    struct block_tree_path path;
    int i;
    struct storage_file_handle file;

    fs_file_tree_init(tr->fs, &files);
    block_mac_copy(tr, &files.root, files_root);
    block_tree_walk(tr, &files, 0, true, &path);
    if (!block_tree_path_get_key(&path)) {
        /* No files, so we just need to track the tree root. */
        block_set_remove_block(tr, new_free_set,
                               block_mac_to_block(tr, files_root));
        return;
    }
    while (block_tree_path_get_key(&path)) {
        /*
         * We only remove a tree node the first time we see it. Because we walk
         * the tree in order, the first time we see a node we will visit its
         * lowest child i.e. path.entry[i].index == 0. When index > 0 we have
         * already visited and removed all parent nodes.
         */
        for (i = path.count - 1; i >= 0 && path.entry[i].index == 0; i--) {
            block = block_mac_to_block(tr, &path.entry[i].block_mac);
            block_set_remove_block(tr, new_free_set, block);
        }
        file.block_mac = block_tree_path_get_data_block_mac(&path);
        file_rebuild_free_set(tr, new_free_set, &file);
        block_tree_path_next(&path);
    }
}