source: mainline/uspace/srv/fs/ext4fs/ext4fs_ops.c@ bae2a79e

/*
 * Copyright (c) 2012 Frantisek Princ
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup fs
 * @{
 */ 

/**
 * @file        ext4fs_ops.c
 * @brief       VFS operations for EXT4 filesystem.
 */

#include <errno.h>
#include <fibril_synch.h>
#include <libext4.h>
#include <libfs.h>
#include <macros.h>
#include <malloc.h>
#include <string.h>
#include <adt/hash_table.h>
#include <ipc/loc.h>
#include "ext4fs.h"
#include "../../vfs/vfs.h"

#define EXT4FS_NODE(node)       ((node) ? (ext4fs_node_t *) (node)->data : NULL)

#define OPEN_NODES_KEYS 2
#define OPEN_NODES_DEV_HANDLE_KEY 0
#define OPEN_NODES_INODE_KEY 1
#define OPEN_NODES_BUCKETS 256

/**
 * Type for holding an instance of mounted partition.
 */
typedef struct ext4fs_instance {
        link_t link;
        service_id_t service_id;
        ext4_filesystem_t *filesystem;
        unsigned int open_nodes_count;
} ext4fs_instance_t;

/**
 * Type for wrapping common fs_node and add some useful pointers.
 */
typedef struct ext4fs_node {
        ext4fs_instance_t *instance;
        ext4_inode_ref_t *inode_ref;
        fs_node_t *fs_node;
        link_t link;
        unsigned int references;
} ext4fs_node_t;

// Forward declarations of auxiliary functions

static int ext4fs_read_directory(ipc_callid_t, aoff64_t, size_t,
    ext4fs_instance_t *, ext4_inode_ref_t *, size_t *);
static int ext4fs_read_file(ipc_callid_t, aoff64_t, size_t, ext4fs_instance_t *,
    ext4_inode_ref_t *, size_t *);
static bool ext4fs_is_dots(const uint8_t *, size_t);
static int ext4fs_instance_get(service_id_t, ext4fs_instance_t **);
static int ext4fs_node_get_core(fs_node_t **, ext4fs_instance_t *, fs_index_t);
static int ext4fs_node_put_core(ext4fs_node_t *);

// Forward declarations of EXT4 libfs operations.

static int ext4fs_root_get(fs_node_t **, service_id_t);
static int ext4fs_match(fs_node_t **, fs_node_t *, const char *);
static int ext4fs_node_get(fs_node_t **, service_id_t, fs_index_t);
static int ext4fs_node_open(fs_node_t *);
static int ext4fs_node_put(fs_node_t *);
static int ext4fs_create_node(fs_node_t **, service_id_t, int);
static int ext4fs_destroy_node(fs_node_t *);
static int ext4fs_link(fs_node_t *, fs_node_t *, const char *);
static int ext4fs_unlink(fs_node_t *, fs_node_t *, const char *);
static int ext4fs_has_children(bool *, fs_node_t *);
static fs_index_t ext4fs_index_get(fs_node_t *);
static aoff64_t ext4fs_size_get(fs_node_t *);
static unsigned ext4fs_lnkcnt_get(fs_node_t *);
static bool ext4fs_is_directory(fs_node_t *);
static bool ext4fs_is_file(fs_node_t *node);
static service_id_t ext4fs_service_get(fs_node_t *node);

// Static variables

static LIST_INITIALIZE(instance_list);
static FIBRIL_MUTEX_INITIALIZE(instance_list_mutex);
static hash_table_t open_nodes;
static FIBRIL_MUTEX_INITIALIZE(open_nodes_lock);

/* Hash table interface for open nodes hash table */
static hash_index_t open_nodes_hash(unsigned long key[])
{
        /* TODO: This is very simple and probably can be improved */
        return key[OPEN_NODES_INODE_KEY] % OPEN_NODES_BUCKETS;
}

/** Compare given item with values in hash table.
 *
 * @return      bool result of compare operation
 */
static int open_nodes_compare(unsigned long key[], hash_count_t keys,
    link_t *item)
{
        ext4fs_node_t *enode = hash_table_get_instance(item, ext4fs_node_t, link);
        assert(keys > 0);
        if (enode->instance->service_id !=
            ((service_id_t) key[OPEN_NODES_DEV_HANDLE_KEY])) {
                return false;
        }
        if (keys == 1) {
                return true;
        }
        assert(keys == 2);
        return (enode->inode_ref->index == key[OPEN_NODES_INODE_KEY]);
}

/** Empty callback to correct hash table initialization.
 *
 */
static void open_nodes_remove_cb(link_t *link)
{
        /* We don't use remove callback for this hash table */
}

static hash_table_operations_t open_nodes_ops = {
        .hash = open_nodes_hash,
        .compare = open_nodes_compare,
        .remove_callback = open_nodes_remove_cb,
};


/** Basic initialization of the driver.
 *
 * There is only needed to create hash table for storing open nodes.
 *
 * @return      error code
 */
int ext4fs_global_init(void)
{
        if (!hash_table_create(&open_nodes, OPEN_NODES_BUCKETS,
            OPEN_NODES_KEYS, &open_nodes_ops)) {
                return ENOMEM;
        }
        return EOK;
}

/* Finalization of the driver.
 *
 * There is only needed to destroy hash table.
 *
 * @return      error code
 */
int ext4fs_global_fini(void)
{
        hash_table_destroy(&open_nodes);
        return EOK;
}


/*
 * EXT4 libfs operations.
 */

/** Get instance from internal table by service_id.
 *
 * @param service_id    device identifier
 * @param inst          output instance if successful operation
 * @return              error code
 */
int ext4fs_instance_get(service_id_t service_id, ext4fs_instance_t **inst)
{
        fibril_mutex_lock(&instance_list_mutex);

        if (list_empty(&instance_list)) {
                fibril_mutex_unlock(&instance_list_mutex);
                return EINVAL;
        }

        ext4fs_instance_t *tmp;
        list_foreach(instance_list, link) {
                tmp = list_get_instance(link, ext4fs_instance_t, link);

                if (tmp->service_id == service_id) {
                        *inst = tmp;
                        fibril_mutex_unlock(&instance_list_mutex);
                        return EOK;
                }
        }

        fibril_mutex_unlock(&instance_list_mutex);
        return EINVAL;
}


/** Get root node of filesystem specified by service_id.
 * 
 * @param rfn           output pointer to loaded node
 * @param service_id    device to load root node from
 * @return              error code
 */
int ext4fs_root_get(fs_node_t **rfn, service_id_t service_id)
{
        return ext4fs_node_get(rfn, service_id, EXT4_INODE_ROOT_INDEX);
}

/** Check if specified name (component) matches with any directory entry.
 * 
 * If match is found, load and return matching node.
 *
 * @param rfn           output pointer to node if operation successful
 * @param pfn           parent directory node
 * @param component     name to check directory for
 * @return              error code
 */
int ext4fs_match(fs_node_t **rfn, fs_node_t *pfn, const char *component)
{
        int rc;

        ext4fs_node_t *eparent = EXT4FS_NODE(pfn);
        ext4_filesystem_t *fs = eparent->instance->filesystem;

        if (!ext4_inode_is_type(fs->superblock, eparent->inode_ref->inode,
            EXT4_INODE_MODE_DIRECTORY)) {
                return ENOTDIR;
        }

        // Try to find entry
        ext4_directory_search_result_t result;
        rc = ext4_directory_find_entry(&result, eparent->inode_ref, component);
        if (rc != EOK) {
                if (rc == ENOENT) {
                        *rfn = NULL;
                        return EOK;
                }
                return rc;
        }

        // Load node from search result
        uint32_t inode = ext4_directory_entry_ll_get_inode(result.dentry);
        rc = ext4fs_node_get_core(rfn, eparent->instance, inode);
        if (rc != EOK) {
                return rc;
        }

        // Destroy search result structure
        rc = ext4_directory_destroy_result(&result);
        if (rc != EOK) {
                return rc;
        }

        return EOK;
}

/** Get node specified by index
 *
 * It's wrapper for node_put_core operation
 *
 * @param rfn           output pointer to loaded node if operation successful
 * @param service_id    device identifier
 * @param index         node index (here i-node number)
 * @return              error code
 */
int ext4fs_node_get(fs_node_t **rfn, service_id_t service_id, fs_index_t index)
{
        int rc;

        ext4fs_instance_t *inst;
        rc = ext4fs_instance_get(service_id, &inst);
        if (rc != EOK) {
                return rc;
        }

        return ext4fs_node_get_core(rfn, inst, index);
}

/** Main function for getting node from the filesystem. 
 *
 * @param rfn           output point to loaded node if operation successful
 * @param inst          instance of filesystem
 * @param index         index of node (i-node number)
 * @return              error code
 */
int ext4fs_node_get_core(fs_node_t **rfn, ext4fs_instance_t *inst,
                fs_index_t index)
{
        int rc;

        fibril_mutex_lock(&open_nodes_lock);

        /* Check if the node is not already open */
        unsigned long key[] = {
                [OPEN_NODES_DEV_HANDLE_KEY] = inst->service_id,
                [OPEN_NODES_INODE_KEY] = index,
        };

        link_t *already_open = hash_table_find(&open_nodes, key);
        ext4fs_node_t *enode = NULL;
        if (already_open) {
                enode = hash_table_get_instance(already_open, ext4fs_node_t, link);
                *rfn = enode->fs_node;
                enode->references++;

                fibril_mutex_unlock(&open_nodes_lock);
                return EOK;
        }

        // Prepare new enode
        enode = malloc(sizeof(ext4fs_node_t));
        if (enode == NULL) {
                fibril_mutex_unlock(&open_nodes_lock);
                return ENOMEM;
        }

        // Prepare new fs_node and initialize
        fs_node_t *fs_node = malloc(sizeof(fs_node_t));
        if (fs_node == NULL) {
                free(enode);
                fibril_mutex_unlock(&open_nodes_lock);
                return ENOMEM;
        }
        fs_node_initialize(fs_node);

        // Load i-node from filesystem
        ext4_inode_ref_t *inode_ref;
        rc = ext4_filesystem_get_inode_ref(inst->filesystem, index, &inode_ref);
        if (rc != EOK) {
                free(enode);
                free(fs_node);
                fibril_mutex_unlock(&open_nodes_lock);
                return rc;
        }

        // Initialize enode
        enode->inode_ref = inode_ref;
        enode->instance = inst;
        enode->references = 1;
        enode->fs_node = fs_node;
        link_initialize(&enode->link);

        fs_node->data = enode;
        *rfn = fs_node;

        hash_table_insert(&open_nodes, key, &enode->link);
        inst->open_nodes_count++;

        fibril_mutex_unlock(&open_nodes_lock);

        return EOK;
}

/** Put previously loaded node.
 *
 * @param enode         node to put back
 * @return              error code
 */
int ext4fs_node_put_core(ext4fs_node_t *enode)
{
        int rc;
        unsigned long key[] = {
                [OPEN_NODES_DEV_HANDLE_KEY] = enode->instance->service_id,
                [OPEN_NODES_INODE_KEY] = enode->inode_ref->index,
        };

        hash_table_remove(&open_nodes, key, OPEN_NODES_KEYS);
        assert(enode->instance->open_nodes_count > 0);
        enode->instance->open_nodes_count--;

        // Put inode back in filesystem
        rc = ext4_filesystem_put_inode_ref(enode->inode_ref);
        if (rc != EOK) {
                return rc;
        }

        // Destroy data structure
        free(enode->fs_node);
        free(enode);

        return EOK;
}


/** Open node.
 *
 * This operation is stateless in this driver.
 *
 * @param fn    node to open
 * @return      error code (EOK)
 */
int ext4fs_node_open(fs_node_t *fn)
{
        // Stateless operation
        return EOK;
}


/** Put previously loaded node.
 *
 * It's wrapper for node_put_core operation
 *
 * @param fn    node to put back
 * @return      error code
 */
int ext4fs_node_put(fs_node_t *fn)
{
        int rc;

        fibril_mutex_lock(&open_nodes_lock);

        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        assert(enode->references > 0);
        enode->references--;
        if (enode->references == 0) {
                rc = ext4fs_node_put_core(enode);
                if (rc != EOK) {
                        fibril_mutex_unlock(&open_nodes_lock);
                        return rc;
                }
        }

        fibril_mutex_unlock(&open_nodes_lock);

        return EOK;
}


/** Create new node in filesystem.
 *
 * @param rfn           output pointer to newly created node if successful
 * @param service_id    device identifier, where the filesystem is
 * @param flags         flags for specification of new node parameters
 * @return              error code
 */
int ext4fs_create_node(fs_node_t **rfn, service_id_t service_id, int flags)
{
        int rc;

        // Allocate enode
        ext4fs_node_t *enode;
        enode = malloc(sizeof(ext4fs_node_t));
        if (enode == NULL) {
                return ENOMEM;
        }

        // Allocate fs_node
        fs_node_t *fs_node;
        fs_node = malloc(sizeof(fs_node_t));
        if (fs_node == NULL) {
                free(enode);
                return ENOMEM;
        }

        // Load instance
        ext4fs_instance_t *inst;
        rc = ext4fs_instance_get(service_id, &inst);
        if (rc != EOK) {
                free(enode);
                free(fs_node);
                return rc;
        }

        // Allocate new i-node in filesystem
        ext4_inode_ref_t *inode_ref;
        rc = ext4_filesystem_alloc_inode(inst->filesystem, &inode_ref, flags);
        if (rc != EOK) {
                free(enode);
                free(fs_node);
                return rc;
        }

        // Do some interconnections in references
        enode->inode_ref = inode_ref;
        enode->instance = inst;
        enode->references = 1;

        link_initialize(&enode->link);

        unsigned long key[] = {
                [OPEN_NODES_DEV_HANDLE_KEY] = inst->service_id,
                [OPEN_NODES_INODE_KEY] = inode_ref->index,
        };

        fibril_mutex_lock(&open_nodes_lock);
        hash_table_insert(&open_nodes, key, &enode->link);
        fibril_mutex_unlock(&open_nodes_lock);
        inst->open_nodes_count++;

        enode->inode_ref->dirty = true;

        fs_node_initialize(fs_node);
        fs_node->data = enode;
        enode->fs_node = fs_node;
        *rfn = fs_node;

        return EOK;
}


/** Destroy existing node.
 *
 * @param fs    node to destroy
 * @return      error code
 */
int ext4fs_destroy_node(fs_node_t *fn)
{
        int rc;

        // If directory, check for children
        bool has_children;
        rc = ext4fs_has_children(&has_children, fn);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                return rc;
        }

        if (has_children) {
                ext4fs_node_put(fn);
                return EINVAL;
        }

        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        ext4_filesystem_t *fs = enode->instance->filesystem;
        ext4_inode_ref_t *inode_ref = enode->inode_ref;

        // Release data blocks
        rc = ext4_filesystem_truncate_inode(inode_ref, 0);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                return rc;
        }

        // Handle orphans
        uint32_t rev_level = ext4_superblock_get_rev_level(fs->superblock);
        if (rev_level > 0) {
                ext4_filesystem_delete_orphan(inode_ref);
        }

        // TODO set real deletion time when it will be supported,
        // temporary set fake time
//      time_t now = time(NULL);
        ext4_inode_set_deletion_time(inode_ref->inode, 12345678);
        inode_ref->dirty = true;

        // Free inode
        rc = ext4_filesystem_free_inode(inode_ref);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                return rc;
        }

        ext4fs_node_put(fn);
        return EOK;
}


/** Link the specfied node to directory.
 *
 * @param pfn           parent node to link in
 * @param cfn           node to be linked
 * @param name          name which will be assigned to directory entry
 * @return              error code
 */
int ext4fs_link(fs_node_t *pfn, fs_node_t *cfn, const char *name)
{
        int rc;

        // Check maximum name length
        if (strlen(name) > EXT4_DIRECTORY_FILENAME_LEN) {
                return ENAMETOOLONG;
        }
        ext4fs_node_t *parent = EXT4FS_NODE(pfn);
        ext4fs_node_t *child = EXT4FS_NODE(cfn);
        ext4_filesystem_t *fs = parent->instance->filesystem;

        // Add entry to parent directory
        rc = ext4_directory_add_entry(parent->inode_ref, name, child->inode_ref);
        if (rc != EOK) {
                return rc;
        }

        // Fill new dir -> add '.' and '..' entries
        if (ext4_inode_is_type(fs->superblock, child->inode_ref->inode, EXT4_INODE_MODE_DIRECTORY)) {

                rc = ext4_directory_add_entry(child->inode_ref, ".", child->inode_ref);
                if (rc != EOK) {
                        ext4_directory_remove_entry(parent->inode_ref, name);
                        return rc;
                }

                rc = ext4_directory_add_entry(child->inode_ref, "..", parent->inode_ref);
                if (rc != EOK) {
                        ext4_directory_remove_entry(parent->inode_ref, name);
                        ext4_directory_remove_entry(child->inode_ref, ".");
                        return rc;
                }

                // Initialize directory index if supported
                if (ext4_superblock_has_feature_compatible(
                                fs->superblock, EXT4_FEATURE_COMPAT_DIR_INDEX)) {

                        rc = ext4_directory_dx_init(child->inode_ref);
                        if (rc != EOK) {
                                return rc;
                        }

                        ext4_inode_set_flag(child->inode_ref->inode, EXT4_INODE_FLAG_INDEX);
                        child->inode_ref->dirty = true;
                }

                uint16_t parent_links = ext4_inode_get_links_count(parent->inode_ref->inode);
                parent_links++;
                ext4_inode_set_links_count(parent->inode_ref->inode, parent_links);

                parent->inode_ref->dirty = true;

        }

        uint16_t child_links = ext4_inode_get_links_count(child->inode_ref->inode);
        child_links++;
        ext4_inode_set_links_count(child->inode_ref->inode, child_links);

        child->inode_ref->dirty = true;

        return EOK;
}


/** Unlink node from specified directory.
 *
 * @param pfn           parent node to delete node from
 * @param cfn           child node to be unlinked from directory
 * @param name          name of entry that will be removed
 * @return              error code
 */
int ext4fs_unlink(fs_node_t *pfn, fs_node_t *cfn, const char *name)
{
        int rc;

        bool has_children;
        rc = ext4fs_has_children(&has_children, cfn);
        if (rc != EOK) {
                return rc;
        }

        // Cannot unlink non-empty node
        if (has_children) {
                return ENOTEMPTY;
        }

        // Remove entry from parent directory
        ext4_inode_ref_t *parent = EXT4FS_NODE(pfn)->inode_ref;
        ext4_filesystem_t *fs = EXT4FS_NODE(pfn)->instance->filesystem;
        rc = ext4_directory_remove_entry(parent, name);
        if (rc != EOK) {
                return rc;
        }

        // Decrement links count
        ext4_inode_ref_t * child_inode_ref = EXT4FS_NODE(cfn)->inode_ref;

        uint32_t lnk_count = ext4_inode_get_links_count(child_inode_ref->inode);
        lnk_count--;

        // If directory - handle links from parent
        if (lnk_count <= 1 && ext4fs_is_directory(cfn)) {

                assert(lnk_count == 1);
                lnk_count--;

                ext4_inode_ref_t *parent_inode_ref = EXT4FS_NODE(pfn)->inode_ref;

                uint32_t parent_lnk_count = ext4_inode_get_links_count(
                                parent_inode_ref->inode);

                parent_lnk_count--;
                ext4_inode_set_links_count(parent_inode_ref->inode, parent_lnk_count);

                parent->dirty = true;
        }

        uint32_t rev_level = ext4_superblock_get_rev_level(fs->superblock);
        if ((rev_level > 0) && (lnk_count == 0)) {
                ext4_filesystem_add_orphan(child_inode_ref);
        }

        // TODO set timestamps for parent (when we have wall-clock time)
//      time_t now = time(NULL);
//      ext4_inode_set_change_inode_time(parent->inode, (uint32_t)now);
//      ext4_inode_set_modification_time(parent->inode, (uint32_t)now);
//      parent->dirty = true;

        // TODO set timestamp for inode
//      ext4_inode_set_change_inode_time(child_inode_ref->inode, (uint32_t)now);
        ext4_inode_set_links_count(child_inode_ref->inode, lnk_count);
        child_inode_ref->dirty = true;

        return EOK;
}


/** Check if specified node has children.
 * 
 * For files is response allways false and check is executed only for directories.
 *
 * @param has_children          output value for response
 * @param fn                    node to check
 * @return                      error code
 */
int ext4fs_has_children(bool *has_children, fs_node_t *fn)
{
        int rc;

        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        ext4_filesystem_t *fs = enode->instance->filesystem;

        // Check if node is directory
        if (!ext4_inode_is_type(fs->superblock, enode->inode_ref->inode,
            EXT4_INODE_MODE_DIRECTORY)) {
                *has_children = false;
                return EOK;
        }

        ext4_directory_iterator_t it;
        rc = ext4_directory_iterator_init(&it, enode->inode_ref, 0);
        if (rc != EOK) {
                return rc;
        }

        /* Find a non-empty directory entry */
        bool found = false;
        while (it.current != NULL) {
                if (it.current->inode != 0) {
                        uint16_t name_size = ext4_directory_entry_ll_get_name_length(fs->superblock,
                                it.current);
                        if (!ext4fs_is_dots(it.current->name, name_size)) {
                                found = true;
                                break;
                        }
                }

                rc = ext4_directory_iterator_next(&it);
                if (rc != EOK) {
                        ext4_directory_iterator_fini(&it);
                        return rc;
                }
        }

        rc = ext4_directory_iterator_fini(&it);
        if (rc != EOK) {
                return rc;
        }

        *has_children = found;

        return EOK;
}


/** Unpack index number from node.
 *      
 * @param fn    node to load index from
 * @return      index number of i-node
 */
fs_index_t ext4fs_index_get(fs_node_t *fn)
{
        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        return enode->inode_ref->index;
}


/** Get real size of file / directory.
 *
 * @param fn    node to get size of
 * @return      real size of node
 */
aoff64_t ext4fs_size_get(fs_node_t *fn)
{
        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        ext4_superblock_t *sb = enode->instance->filesystem->superblock;
        return ext4_inode_get_size(sb, enode->inode_ref->inode);
}


/** Get number of links to specified node.
 *
 * @param fn    node to get links to
 * @return      number of links
 */
unsigned ext4fs_lnkcnt_get(fs_node_t *fn)
{
        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        uint32_t lnkcnt = ext4_inode_get_links_count(enode->inode_ref->inode);

        if (ext4fs_is_directory(fn)) {
                if (lnkcnt > 1) {
                        return 1;
                } else {
                        return 0;
                }
        }

        // For regular files return real links count
        return lnkcnt;
}


/** Check if node is directory.
 *
 * @param fn    node to check
 * @return      result of check
 */
bool ext4fs_is_directory(fs_node_t *fn)
{
        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        ext4_superblock_t *sb = enode->instance->filesystem->superblock;
        return ext4_inode_is_type(
                        sb, enode->inode_ref->inode, EXT4_INODE_MODE_DIRECTORY);
}


/** Check if node is regular file.
 *
 * @param fn    node to check
 * @return      result of check
 */
bool ext4fs_is_file(fs_node_t *fn)
{
        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        ext4_superblock_t *sb = enode->instance->filesystem->superblock;
        return ext4_inode_is_type(
                        sb, enode->inode_ref->inode, EXT4_INODE_MODE_FILE);
}

/** Extract device identifier from node.
 *
 * @param node  node to extract id from
 * @return      id of device, where is the filesystem
 */
service_id_t ext4fs_service_get(fs_node_t *fn)
{
        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        return enode->instance->service_id;
}

/*
 * libfs operations.
 */
libfs_ops_t ext4fs_libfs_ops = {
        .root_get = ext4fs_root_get,
        .match = ext4fs_match,
        .node_get = ext4fs_node_get,
        .node_open = ext4fs_node_open,
        .node_put = ext4fs_node_put,
        .create = ext4fs_create_node,
        .destroy = ext4fs_destroy_node,
        .link = ext4fs_link,
        .unlink = ext4fs_unlink,
        .has_children = ext4fs_has_children,
        .index_get = ext4fs_index_get,
        .size_get = ext4fs_size_get,
        .lnkcnt_get = ext4fs_lnkcnt_get,
        .is_directory = ext4fs_is_directory,
        .is_file = ext4fs_is_file,
        .service_get = ext4fs_service_get
};


/*
 * VFS operations.
 */

/** Mount operation. 
 *
 * Try to mount specified filesystem from device.
 * 
 * @param service_id    identifier of device
 * @param opts          mount options
 * @param index         output value - index of root node
 * @param size          output value - size of root node
 * @param lnkcnt        output value - link count of root node
 * @return              error code
 */
static int ext4fs_mounted(service_id_t service_id, const char *opts,
   fs_index_t *index, aoff64_t *size, unsigned *lnkcnt)
{
        int rc;

        /* Allocate libext4 filesystem structure */
        ext4_filesystem_t *fs;
        fs = (ext4_filesystem_t *) malloc(sizeof(ext4_filesystem_t));
        if (fs == NULL) {
                return ENOMEM;
        }

        /* Allocate instance structure */
        ext4fs_instance_t *inst;
        inst = (ext4fs_instance_t *) malloc(sizeof(ext4fs_instance_t));
        if (inst == NULL) {
                free(fs);
                return ENOMEM;
        }

        /* Initialize the filesystem */
        rc = ext4_filesystem_init(fs, service_id);
        if (rc != EOK) {
                free(fs);
                free(inst);
                return rc;
        }

        /* Do some sanity checking */
        rc = ext4_filesystem_check_sanity(fs);
        if (rc != EOK) {
                ext4_filesystem_fini(fs, false);
                free(fs);
                free(inst);
                return rc;
        }

        /* Check flags */
        bool read_only;
        rc = ext4_filesystem_check_features(fs, &read_only);
        if (rc != EOK) {
                ext4_filesystem_fini(fs, false);
                free(fs);
                free(inst);
                return rc;
        }

        /* Initialize instance */
        link_initialize(&inst->link);
        inst->service_id = service_id;
        inst->filesystem = fs;
        inst->open_nodes_count = 0;

        /* Read root node */
        fs_node_t *root_node;
        rc = ext4fs_node_get_core(&root_node, inst, EXT4_INODE_ROOT_INDEX);
        if (rc != EOK) {
                ext4_filesystem_fini(fs, false);
                free(fs);
                free(inst);
                return rc;
        }

        /* Add instance to the list */
        fibril_mutex_lock(&instance_list_mutex);
        list_append(&inst->link, &instance_list);
        fibril_mutex_unlock(&instance_list_mutex);

        ext4fs_node_t *enode = EXT4FS_NODE(root_node);

        *index = EXT4_INODE_ROOT_INDEX;
        *size = ext4_inode_get_size(fs->superblock, enode->inode_ref->inode);
        *lnkcnt = 1;

        ext4fs_node_put(root_node);

        return EOK;
}

/** Unmount operation.
 *
 * Correctly release the filesystem.
 *
 * @param service_id    device to be unmounted
 * @return              error code
 */
static int ext4fs_unmounted(service_id_t service_id)
{
        int rc;

        ext4fs_instance_t *inst;
        rc = ext4fs_instance_get(service_id, &inst);
        if (rc != EOK) {
                return rc;
        }

        fibril_mutex_lock(&open_nodes_lock);

        if (inst->open_nodes_count != 0) {
                fibril_mutex_unlock(&open_nodes_lock);
                return EBUSY;
        }

        /* Remove the instance from the list */
        fibril_mutex_lock(&instance_list_mutex);
        list_remove(&inst->link);
        fibril_mutex_unlock(&instance_list_mutex);

        fibril_mutex_unlock(&open_nodes_lock);

        return ext4_filesystem_fini(inst->filesystem, true);
}


/** Read bytes from node.
 *
 * @param service_id    device to read data from
 * @param index         number of node to read from
 * @param pos           position where the read should be started
 * @param rbytes        output value, where the real size was returned
 * @return              error code
 */
static int ext4fs_read(service_id_t service_id, fs_index_t index,
                aoff64_t pos, size_t *rbytes)
{
        int rc;

        /*
         * Receive the read request.
         */
        ipc_callid_t callid;
        size_t size;
        if (!async_data_read_receive(&callid, &size)) {
                async_answer_0(callid, EINVAL);
                return EINVAL;
        }

        ext4fs_instance_t *inst;
        rc = ext4fs_instance_get(service_id, &inst);
        if (rc != EOK) {
                async_answer_0(callid, rc);
                return rc;
        }

        // Load i-node
        ext4_inode_ref_t *inode_ref;
        rc = ext4_filesystem_get_inode_ref(inst->filesystem, index, &inode_ref);
        if (rc != EOK) {
                async_answer_0(callid, rc);
                return rc;
        }

        // Read from i-node by type
        if (ext4_inode_is_type(inst->filesystem->superblock, inode_ref->inode,
                        EXT4_INODE_MODE_FILE)) {
                rc = ext4fs_read_file(callid, pos, size, inst, inode_ref,
                                rbytes);
        } else if (ext4_inode_is_type(inst->filesystem->superblock,
                        inode_ref->inode, EXT4_INODE_MODE_DIRECTORY)) {
                rc = ext4fs_read_directory(callid, pos, size, inst, inode_ref,
                                rbytes);
        } else {
                /* Other inode types not supported */
                async_answer_0(callid, ENOTSUP);
                rc = ENOTSUP;
        }

        ext4_filesystem_put_inode_ref(inode_ref);

        return rc;
}

/** Check if filename is dot or dotdot (reserved names).
 *
 * @param name          name to check
 * @param name_size     length of string name
 * @return              result of the check
 */
bool ext4fs_is_dots(const uint8_t *name, size_t name_size)
{
        if (name_size == 1 && name[0] == '.') {
                return true;
        }

        if (name_size == 2 && name[0] == '.' && name[1] == '.') {
                return true;
        }

        return false;
}

/** Read data from directory.
 *
 * @param callid        IPC id of call (for communication)
 * @param pos           position to start reading from
 * @param size          how many bytes to read
 * @param inst          filesystem instance
 * @param inode_ref     node to read data from
 * @param rbytes        output value to return real number of bytes was read
 * @return              error code
 */
int ext4fs_read_directory(ipc_callid_t callid, aoff64_t pos, size_t size,
    ext4fs_instance_t *inst, ext4_inode_ref_t *inode_ref, size_t *rbytes)
{
        int rc;

        ext4_directory_iterator_t it;
        rc = ext4_directory_iterator_init(&it, inode_ref, pos);
        if (rc != EOK) {
                async_answer_0(callid, rc);
                return rc;
        }

        /* Find next interesting directory entry.
         * We want to skip . and .. entries
         * as these are not used in HelenOS
         */
        bool found = false;
        while (it.current != NULL) {

                if (it.current->inode == 0) {
                        goto skip;
                }

                uint16_t name_size = ext4_directory_entry_ll_get_name_length(
                    inst->filesystem->superblock, it.current);

                /* skip . and .. */
                if (ext4fs_is_dots(it.current->name, name_size)) {
                        goto skip;
                }

                /* The on-disk entry does not contain \0 at the end
                 * end of entry name, so we copy it to new buffer
                 * and add the \0 at the end
                 */
                uint8_t *buf = malloc(name_size+1);
                if (buf == NULL) {
                        ext4_directory_iterator_fini(&it);
                        async_answer_0(callid, ENOMEM);
                        return ENOMEM;
                }
                memcpy(buf, &it.current->name, name_size);
                *(buf + name_size) = 0;
                found = true;
                (void) async_data_read_finalize(callid, buf, name_size + 1);
                free(buf);
                break;

skip:
                rc = ext4_directory_iterator_next(&it);
                if (rc != EOK) {
                        ext4_directory_iterator_fini(&it);
                        async_answer_0(callid, rc);
                        return rc;
                }
        }

        uint64_t next;
        if (found) {
                rc = ext4_directory_iterator_next(&it);
                if (rc != EOK) {
                        return rc;
                }
                next = it.current_offset;
        }

        rc = ext4_directory_iterator_fini(&it);
        if (rc != EOK) {
                return rc;
        }

        // Prepare return values
        if (found) {
                *rbytes = next - pos;
                return EOK;
        } else {
                async_answer_0(callid, ENOENT);
                return ENOENT;
        }
}


/** Read data from file.
 *
 * @param callid        IPC id of call (for communication)
 * @param pos           position to start reading from
 * @param size          how many bytes to read
 * @param inst          filesystem instance
 * @param inode_ref     node to read data from
 * @param rbytes        output value to return real number of bytes was read
 * @return              error code
 */
int ext4fs_read_file(ipc_callid_t callid, aoff64_t pos, size_t size,
    ext4fs_instance_t *inst, ext4_inode_ref_t *inode_ref, size_t *rbytes)
{
        int rc;

        ext4_superblock_t *sb = inst->filesystem->superblock;
        uint64_t file_size = ext4_inode_get_size(sb, inode_ref->inode);

        if (pos >= file_size) {
                /* Read 0 bytes successfully */
                async_data_read_finalize(callid, NULL, 0);
                *rbytes = 0;
                return EOK;
        }

        /* For now, we only read data from one block at a time */
        uint32_t block_size = ext4_superblock_get_block_size(sb);
        aoff64_t file_block = pos / block_size;
        uint32_t offset_in_block = pos % block_size;
        uint32_t bytes = min(block_size - offset_in_block, size);

        /* Handle end of file */
        if (pos + bytes > file_size) {
                bytes = file_size - pos;
        }

        /* Get the real block number */
        uint32_t fs_block;
        rc = ext4_filesystem_get_inode_data_block_index(inode_ref, file_block, &fs_block);
        if (rc != EOK) {
                async_answer_0(callid, rc);
                return rc;
        }

        /* Check for sparse file
         * If ext4_filesystem_get_inode_data_block_index returned
         * fs_block == 0, it means that the given block is not allocated for the
         * file and we need to return a buffer of zeros
         */
        uint8_t *buffer;
        if (fs_block == 0) {
                buffer = malloc(bytes);
                if (buffer == NULL) {
                        async_answer_0(callid, ENOMEM);
                        return ENOMEM;
                }

                memset(buffer, 0, bytes);

                async_data_read_finalize(callid, buffer, bytes);
                *rbytes = bytes;

                free(buffer);

                return EOK;
        }

        /* Usual case - we need to read a block from device */
        block_t *block;
        rc = block_get(&block, inst->service_id, fs_block, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                async_answer_0(callid, rc);
                return rc;
        }

        assert(offset_in_block + bytes <= block_size);
        async_data_read_finalize(callid, block->data + offset_in_block, bytes);

        rc = block_put(block);
        if (rc != EOK) {
                return rc;
        }

        *rbytes = bytes;
        return EOK;
}


/** Write bytes to file
 *
 * @param service_id    device identifier
 * @param index         i-node number of file
 * @param pos           position in file to start reading from
 * @param wbytes        output value - real number of written bytes
 * @param nsize         output value - new size of i-node
 * @return              error code
 */
static int ext4fs_write(service_id_t service_id, fs_index_t index,
                aoff64_t pos, size_t *wbytes, aoff64_t *nsize)
{
        int rc;

        fs_node_t *fn;
        rc = ext4fs_node_get(&fn, service_id, index);
        if (rc != EOK) {
                return rc;
        }

        ipc_callid_t callid;
        size_t len;
        if (!async_data_write_receive(&callid, &len)) {
                rc = EINVAL;
                ext4fs_node_put(fn);
                async_answer_0(callid, rc);
                return rc;
        }


        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        ext4_filesystem_t *fs = enode->instance->filesystem;

        uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);

        // Prevent writing to more than one block
        uint32_t bytes = min(len, block_size - (pos % block_size));

        int flags = BLOCK_FLAGS_NONE;
        if (bytes == block_size) {
                flags = BLOCK_FLAGS_NOREAD;
        }

        uint32_t iblock =  pos / block_size;
        uint32_t fblock;

        // Load inode
        ext4_inode_ref_t *inode_ref = enode->inode_ref;
        rc = ext4_filesystem_get_inode_data_block_index(inode_ref, iblock, &fblock);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                async_answer_0(callid, rc);
                return rc;
        }

        // Check for sparse file
        if (fblock == 0) {

                if (ext4_superblock_has_feature_incompatible(
                                fs->superblock, EXT4_FEATURE_INCOMPAT_EXTENTS) &&
                                (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {

                        uint32_t tmp_iblock = 0;
                        do {
                                rc = ext4_filesystem_append_inode_block(inode_ref, &fblock, &tmp_iblock);
                                if (rc != EOK) {
                                        ext4fs_node_put(fn);
                                        async_answer_0(callid, rc);
                                        return rc;
                                }
                        } while (tmp_iblock < iblock);

                } else {
                        rc =  ext4_balloc_alloc_block(inode_ref, &fblock);
                        if (rc != EOK) {
                                ext4fs_node_put(fn);
                                async_answer_0(callid, rc);
                                return rc;
                        }

                        rc = ext4_filesystem_set_inode_data_block_index(inode_ref, iblock, fblock);
                        if (rc != EOK) {
                                ext4_balloc_free_block(inode_ref, fblock);
                                ext4fs_node_put(fn);
                                async_answer_0(callid, rc);
                                return rc;
                        }
                }

                flags = BLOCK_FLAGS_NOREAD;
                inode_ref->dirty = true;
        }

        // Load target block
        block_t *write_block;
        rc = block_get(&write_block, service_id, fblock, flags);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                async_answer_0(callid, rc);
                return rc;
        }

        if (flags == BLOCK_FLAGS_NOREAD) {
                memset(write_block->data, 0, block_size);
        }

        rc = async_data_write_finalize(callid, write_block->data + (pos % block_size), bytes);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                return rc;
        }

        write_block->dirty = true;

        rc = block_put(write_block);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                return rc;
        }

        // Do some counting
        uint32_t old_inode_size = ext4_inode_get_size(fs->superblock, inode_ref->inode);
        if (pos + bytes > old_inode_size) {
                ext4_inode_set_size(inode_ref->inode, pos + bytes);
                inode_ref->dirty = true;
        }

        *nsize = ext4_inode_get_size(fs->superblock, inode_ref->inode);
        *wbytes = bytes;

        return ext4fs_node_put(fn);
}


/** Truncate file.
 *
 * Only the direction to shorter file is supported.
 *
 * @param service_id    device identifier
 * @param index         index if node to truncated
 * @param new_size      new size of file
 * @return              error code
 */
static int ext4fs_truncate(service_id_t service_id, fs_index_t index,
                aoff64_t new_size)
{
        int rc;

        fs_node_t *fn;
        rc = ext4fs_node_get(&fn, service_id, index);
        if (rc != EOK) {
                return rc;
        }

        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        ext4_inode_ref_t *inode_ref = enode->inode_ref;

        rc = ext4_filesystem_truncate_inode(inode_ref, new_size);
        ext4fs_node_put(fn);

        return rc;
}


/** Close file.
 *'
 * @param service_id    device identifier
 * @param index         i-node number
 * @return              error code
 */
static int ext4fs_close(service_id_t service_id, fs_index_t index)
{
        return EOK;
}


/** Destroy node specified by index.
 *
 * @param service_id    device identifier
 * @param index         number of i-node to destroy
 * @return              error code
 */
static int ext4fs_destroy(service_id_t service_id, fs_index_t index)
{
        int rc;

        fs_node_t *fn;
        rc = ext4fs_node_get(&fn, service_id, index);
        if (rc != EOK) {
                return rc;
        }

        /* Destroy the inode */
        return ext4fs_destroy_node(fn);
}

/** Enforce inode synchronization (write) to device. 
 *
 * @param service_id    device identifier
 * @param index         i-node number.
 */
static int ext4fs_sync(service_id_t service_id, fs_index_t index)
{
        int rc;

        fs_node_t *fn;
        rc = ext4fs_node_get(&fn, service_id, index);
        if (rc != EOK) {
                return rc;
        }

        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        enode->inode_ref->dirty = true;

        return ext4fs_node_put(fn);
}

/** VFS operations
 *
 */
vfs_out_ops_t ext4fs_ops = {
        .mounted = ext4fs_mounted,
        .unmounted = ext4fs_unmounted,
        .read = ext4fs_read,
        .write = ext4fs_write,
        .truncate = ext4fs_truncate,
        .close = ext4fs_close,
        .destroy = ext4fs_destroy,
        .sync = ext4fs_sync,
};

/**
 * @}
 */