source: mainline/uspace/lib/ext4/src/ops.c@ 805552d

/*
 * Copyright (c) 2011 Martin Sucha
 * 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 libext4
 * @{
 */
/**
 * @file  ext4fs_ops.c
 * @brief Operations for ext4 filesystem.
 */

#include <errno.h>
#include <ext4/libext4.h>
#include <fibril_synch.h>
#include <libfs.h>
#include <macros.h>
#include <malloc.h>
#include <adt/hash_table.h>
#include <adt/hash.h>
#include <ipc/loc.h>
#include "ext4/ops.h"
//#include "../../vfs/vfs.h"

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

/**
 * 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;
        ht_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 int ext4fs_size_block(service_id_t, uint32_t *);
static int ext4fs_total_block_count(service_id_t, uint64_t *);
static int ext4fs_free_block_count(service_id_t, uint64_t *);

/* 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 */

typedef struct {
        service_id_t service_id;
        fs_index_t index;
} node_key_t;

static size_t open_nodes_key_hash(void *key_arg)
{
        node_key_t *key = (node_key_t *)key_arg;
        return hash_combine(key->service_id, key->index);
}

static size_t open_nodes_hash(const ht_link_t *item)
{
        ext4fs_node_t *enode = hash_table_get_inst(item, ext4fs_node_t, link);
        return hash_combine(enode->instance->service_id, enode->inode_ref->index);      
}

static bool open_nodes_key_equal(void *key_arg, const ht_link_t *item)
{
        node_key_t *key = (node_key_t *)key_arg;
        ext4fs_node_t *enode = hash_table_get_inst(item, ext4fs_node_t, link);
        
        return key->service_id == enode->instance->service_id
                && key->index == enode->inode_ref->index;
}

static hash_table_ops_t open_nodes_ops = {
        .hash = open_nodes_hash,
        .key_hash = open_nodes_key_hash,
        .key_equal = open_nodes_key_equal,
        .equal = NULL,
        .remove_callback = NULL,
};

/** Basic initialization of the driver.
 *
 * This is only needed to create the hash table
 * for storing open nodes.
 *
 * @return Error code
 *
 */
int ext4fs_global_init(void)
{
        if (!hash_table_create(&open_nodes, 0, 0, &open_nodes_ops))
                return ENOMEM;
        
        return EOK;
}

/* Finalization of the driver.
 *
 * This is only needed to destroy the 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;
        }
        
        list_foreach(instance_list, link, ext4fs_instance_t, tmp) {
                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)
{
        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;
        int 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)
                goto exit;

exit:
        ;

        /* Destroy search result structure */
        int const rc2 = ext4_directory_destroy_result(&result);
        return rc == EOK ? rc2 : rc;
}

/** 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)
{
        ext4fs_instance_t *inst;
        int 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)
{
        fibril_mutex_lock(&open_nodes_lock);
        
        /* Check if the node is not already open */
        node_key_t key = {
                .service_id = inst->service_id,
                .index = index
        };
        
        ht_link_t *already_open = hash_table_find(&open_nodes, &key);
        ext4fs_node_t *enode = NULL;
        if (already_open) {
                enode = hash_table_get_inst(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;
        int 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;
        
        fs_node->data = enode;
        *rfn = fs_node;
        
        hash_table_insert(&open_nodes, &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)
{
        hash_table_remove_item(&open_nodes, &enode->link);
        assert(enode->instance->open_nodes_count > 0);
        enode->instance->open_nodes_count--;
        
        /* Put inode back in filesystem */
        int 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 EOK
 *
 */
int ext4fs_node_open(fs_node_t *fn)
{
        /* Stateless operation */
        return EOK;
}

/** Put previously loaded node.
 *
 * A wrapper for node_put_core operation
 *
 * @param fn Node to put back
 * @return Error code
 *
 */
int ext4fs_node_put(fs_node_t *fn)
{
        fibril_mutex_lock(&open_nodes_lock);
        
        ext4fs_node_t *enode = EXT4FS_NODE(fn);
        assert(enode->references > 0);
        enode->references--;
        if (enode->references == 0) {
                int 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)
{
        /* 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;
        int 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;
        
        fibril_mutex_lock(&open_nodes_lock);
        hash_table_insert(&open_nodes, &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)
{
        /* If directory, check for children */
        bool has_children;
        int 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_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;
        }
        
        /*
         * TODO: Sset real deletion time when it will be supported.
         * Temporary set fake deletion time.
         */
        ext4_inode_set_deletion_time(inode_ref->inode, 0xdeadbeef);
        inode_ref->dirty = true;
        
        /* Free inode */
        rc = ext4_filesystem_free_inode(inode_ref);
        if (rc != EOK) {
                ext4fs_node_put(fn);
                return rc;
        }
        
        return ext4fs_node_put(fn);
}

/** 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)
{
        /* Check maximum name length */
        if (str_size(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 */
        int 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)
{
        bool has_children;
        int 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;
        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;
        }

        /*
         * TODO: Update timestamps of the parent
         * (when we have wall-clock time).
         *
         * 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: Update 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)
{
        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;
        int 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;
}

int ext4fs_size_block(service_id_t service_id, uint32_t *size)
{
        ext4fs_instance_t *inst;
        int rc = ext4fs_instance_get(service_id, &inst);
        if (rc != EOK)
                return rc;

        if (NULL == inst)
                return ENOENT;

        ext4_superblock_t *sb = inst->filesystem->superblock;
        *size = ext4_superblock_get_block_size(sb);

        return EOK;
}

int ext4fs_total_block_count(service_id_t service_id, uint64_t *count)
{
        ext4fs_instance_t *inst;
        int rc = ext4fs_instance_get(service_id, &inst);
        if (rc != EOK)
                return rc;

        if (NULL == inst)
                return ENOENT;

        ext4_superblock_t *sb = inst->filesystem->superblock;
        *count = ext4_superblock_get_blocks_count(sb);

        return EOK;
}

int ext4fs_free_block_count(service_id_t service_id, uint64_t *count)
{
        ext4fs_instance_t *inst;
        int rc = ext4fs_instance_get(service_id, &inst);
        if (rc != EOK)
                return rc;

        ext4_superblock_t *sb = inst->filesystem->superblock;
        *count = ext4_superblock_get_free_blocks_count(sb);

        return EOK;
}

/*
 * 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,
        .size_block = ext4fs_size_block,
        .total_block_count = ext4fs_total_block_count,
        .free_block_count = ext4fs_free_block_count
};

/*
 * VFS operations.
 */

/** Probe operation.
 *
 * Try to get information about specified filesystem from device.
 *
 * @param sevice_id Service ID
 * @param info Place to store information
 *
 * @return Error code
 */
static int ext4fs_fsprobe(service_id_t service_id, vfs_fs_probe_info_t *info)
{
        return ENOTSUP;
}

/** 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)
{
        /* Allocate libext4 filesystem structure */
        ext4_filesystem_t *fs = (ext4_filesystem_t *)
            malloc(sizeof(ext4_filesystem_t));
        if (fs == NULL)
                return ENOMEM;
        
        /* Allocate instance structure */
        ext4fs_instance_t *inst = (ext4fs_instance_t *)
            malloc(sizeof(ext4fs_instance_t));
        if (inst == NULL) {
                free(fs);
                return ENOMEM;
        }
        
        enum cache_mode cmode;
        if (str_cmp(opts, "wtcache") == 0)
                cmode = CACHE_MODE_WT;
        else
                cmode = CACHE_MODE_WB;
        
        /* Initialize the filesystem */
        int rc = ext4_filesystem_init(fs, service_id, cmode);
        if (rc != EOK) {
                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);
                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);
                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;
        
        return ext4fs_node_put(root_node);
}

/** 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)
{
        ext4fs_instance_t *inst;
        int 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);
}

/** 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)
{
        /*
         * 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;
        int 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;
        }
        
        int const rc2 = ext4_filesystem_put_inode_ref(inode_ref);
        
        return rc == EOK ? rc2 : 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)
{
        ext4_directory_iterator_t it;
        int 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)
{
        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;
        int 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);
                
                rc = async_data_read_finalize(callid, buffer, bytes);
                *rbytes = bytes;
                
                free(buffer);
                return rc;
        }
        
        /* 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);
        rc = async_data_read_finalize(callid, block->data + offset_in_block, bytes);
        if (rc != EOK) {
                block_put(block);
                return rc;
        }
        
        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)
{
        fs_node_t *fn;
        int 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;
                async_answer_0(callid, rc);
                goto exit;
        }
        
        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) {
                async_answer_0(callid, rc);
                goto exit;
        }
        
        /* 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 last_iblock =
                            ext4_inode_get_size(fs->superblock, inode_ref->inode) /
                            block_size;
                        
                        while (last_iblock < iblock) {
                                rc = ext4_extent_append_block(inode_ref, &last_iblock,
                                    &fblock, true);
                                if (rc != EOK) {
                                        async_answer_0(callid, rc);
                                        goto exit;
                                }
                        }
                        
                        rc = ext4_extent_append_block(inode_ref, &last_iblock,
                            &fblock, false);
                        if (rc != EOK) {
                                async_answer_0(callid, rc);
                                goto exit;
                        }
                } else {
                        rc = ext4_balloc_alloc_block(inode_ref, &fblock);
                        if (rc != EOK) {
                                async_answer_0(callid, rc);
                                goto exit;
                        }
                        
                        rc = ext4_filesystem_set_inode_data_block_index(inode_ref,
                            iblock, fblock);
                        if (rc != EOK) {
                                ext4_balloc_free_block(inode_ref, fblock);
                                async_answer_0(callid, rc);
                                goto exit;
                        }
                }
                
                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) {
                async_answer_0(callid, rc);
                goto exit;
        }
        
        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) {
                block_put(write_block);
                goto exit;
        }

        write_block->dirty = true;

        rc = block_put(write_block);
        if (rc != EOK)
                goto exit;

        /* 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;

exit:
        ;

        int const rc2 = ext4fs_node_put(fn);
        return rc == EOK ? rc2 : rc;
}

/** 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)
{
        fs_node_t *fn;
        int 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);
        int const rc2 = ext4fs_node_put(fn);
        
        return rc == EOK ? rc2 : 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      I-node to destroy
 *
 * @return Error code
 *
 */
static int ext4fs_destroy(service_id_t service_id, fs_index_t index)
{
        fs_node_t *fn;
        int 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)
{
        fs_node_t *fn;
        int 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 = {
        .fsprobe = ext4fs_fsprobe,
        .mounted = ext4fs_mounted,
        .unmounted = ext4fs_unmounted,
        .read = ext4fs_read,
        .write = ext4fs_write,
        .truncate = ext4fs_truncate,
        .close = ext4fs_close,
        .destroy = ext4fs_destroy,
        .sync = ext4fs_sync
};

/**
 * @}
 */