source: mainline/uspace/srv/volsrv/volume.c@ d51cca8

/*
 * Copyright (c) 2018 Jiri Svoboda
 * 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 volsrv
 * @{
 */
/**
 * @file Volume handling
 * @brief
 *
 * Volumes are the file systems (or similar) contained in partitions.
 * Each vol_volume_t can be considered the configuration entry
 * for a volume. Each partition has an associated vol_volume_t.
 *
 * If there is any non-default configuration to be remembered for a
 * volume, the vol_volume_t structure is kept around even after the partition
 * is disassociated from it. Otherwise it is deleted once no longer
 * referenced.
 */

#include <adt/list.h>
#include <errno.h>
#include <fibril_synch.h>
#include <io/log.h>
#include <stdbool.h>
#include <stdlib.h>
#include <str.h>

#include "volume.h"
#include "types/volume.h"

static void vol_volume_delete(vol_volume_t *);
static void vol_volume_add_locked(vol_volumes_t *, vol_volume_t *);
static errno_t vol_volume_lookup_ref_locked(vol_volumes_t *, const char *,
    vol_volume_t **);
static errno_t vol_volumes_load(sif_node_t *, vol_volumes_t *);

/** Allocate new volume structure.
 *
 * @return Pointer to new volume structure
 */
static vol_volume_t *vol_volume_new(void)
{
        vol_volume_t *volume = calloc(1, sizeof(vol_volume_t));

        if (volume == NULL) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Failed allocating volume "
                    "structure. Out of memory.");
                return NULL;
        }

        volume->label = str_dup("");
        volume->mountp = str_dup("");

        if (volume->label == NULL || volume->mountp == NULL) {
                vol_volume_delete(volume);
                return NULL;
        }

        refcount_init(&volume->refcnt);
        link_initialize(&volume->lvolumes);
        volume->volumes = NULL;

        return volume;
}

/** Delete volume structure.
 *
 * @param volume Volume structure
 */
static void vol_volume_delete(vol_volume_t *volume)
{
        log_msg(LOG_DEFAULT, LVL_NOTE, "Freeing volume %p", volume);

        free(volume->label);
        free(volume->mountp);
        free(volume);
}

/** Create list of volumes.
 *
 * @param cfg_path Path to file containing configuration repository in SIF
 * @param rvolumes Place to store pointer to list of volumes.
 * @return EOK on success, ENOMEM if out of memory
 */
errno_t vol_volumes_create(const char *cfg_path,
    vol_volumes_t **rvolumes)
{
        vol_volumes_t *volumes;
        sif_sess_t *repo = NULL;
        sif_trans_t *trans = NULL;
        sif_node_t *node;
        const char *ntype;
        errno_t rc;

        volumes = calloc(1, sizeof(vol_volumes_t));
        if (volumes == NULL)
                return ENOMEM;

        fibril_mutex_initialize(&volumes->lock);
        list_initialize(&volumes->volumes);

        /* Try opening existing repository */
        rc = sif_open(cfg_path, &repo);
        if (rc != EOK) {
                /* Failed to open existing, create new repository */
                rc = sif_create(cfg_path, &repo);
                if (rc != EOK)
                        goto error;

                rc = sif_trans_begin(repo, &trans);
                if (rc != EOK)
                        goto error;

                /* Create 'volumes' node. */
                rc = sif_node_append_child(trans, sif_get_root(repo),
                    "volumes", &volumes->nvolumes);
                if (rc != EOK)
                        goto error;

                rc = sif_trans_end(trans);
                if (rc != EOK)
                        goto error;

                trans = NULL;
        } else {
                /*
                 * Opened existing repo. Find 'volumes' node, should be
                 * the first child of the root node.
                 */
                node = sif_node_first_child(sif_get_root(repo));

                /* Verify it's the correct node type */
                ntype = sif_node_get_type(node);
                if (str_cmp(ntype, "volumes") != 0) {
                        rc = EIO;
                        goto error;
                }

                rc = vol_volumes_load(node, volumes);
                if (rc != EOK)
                        goto error;
        }

        volumes->repo = repo;
        *rvolumes = volumes;

        return EOK;
error:
        if (trans != NULL)
                sif_trans_abort(trans);
        if (repo != NULL)
                (void) sif_close(repo);
        if (volumes != NULL)
                free(volumes);

        return rc;
}

/** Destroy list of volumes.
 *
 * @param volumes List of volumes or @c NULL
 */
void vol_volumes_destroy(vol_volumes_t *volumes)
{
        link_t *link;
        vol_volume_t *volume;

        if (volumes == NULL)
                return;

        link = list_first(&volumes->volumes);
        while (link != NULL) {
                volume = list_get_instance(link, vol_volume_t, lvolumes);

                list_remove(&volume->lvolumes);
                vol_volume_delete(volume);

                link = list_first(&volumes->volumes);
        }

        free(volumes);
}

/** Add new volume structure to list of volumes.
 *
 * @param volumes List of volumes
 * @param volume Volume structure
 */
static void vol_volume_add_locked(vol_volumes_t *volumes,
    vol_volume_t *volume)
{
        assert(fibril_mutex_is_locked(&volumes->lock));
        log_msg(LOG_DEFAULT, LVL_NOTE, "vol_volume_add_locked(%p)", volume);

        volume->volumes = volumes;
        list_append(&volume->lvolumes, &volumes->volumes);
}

/** Look up volume structure with locked volumes lock.
 *
 * If a matching existing volume is found, it is returned. Otherwise
 * a new volume structure is created.
 *
 * @param volumes List of volumes
 * @param label Volume label
 * @param rvolume Place to store pointer to volume structure (existing or new)
 *
 * @return EOK on success, ENOMEM if out of memory
 */
static errno_t vol_volume_lookup_ref_locked(vol_volumes_t *volumes,
    const char *label, vol_volume_t **rvolume)
{
        vol_volume_t *volume;

        assert(fibril_mutex_is_locked(&volumes->lock));

        list_foreach(volumes->volumes, lvolumes, vol_volume_t, volume) {
                if (str_cmp(volume->label, label) == 0 &&
                    str_size(label) > 0) {
                        /* Add reference */
                        refcount_up(&volume->refcnt);
                        *rvolume = volume;
                        return EOK;
                }
        }

        /* No existing volume found. Create a new one. */
        volume = vol_volume_new();
        if (volume == NULL)
                return ENOMEM;

        free(volume->label);
        volume->label = str_dup(label);

        if (volume->label == NULL) {
                vol_volume_delete(volume);
                return ENOMEM;
        }

        vol_volume_add_locked(volumes, volume);

        *rvolume = volume;
        return EOK;
}

/** Look up volume structure.
 *
 * If a matching existing volume is found, it is returned. Otherwise
 * a new volume structure is created.
 *
 * @param volumes List of volumes
 * @param label Volume label
 * @param rvolume Place to store pointer to volume structure (existing or new)
 *
 * @return EOK on success, ENOMEM if out of memory
 */
errno_t vol_volume_lookup_ref(vol_volumes_t *volumes, const char *label,
    vol_volume_t **rvolume)
{
        errno_t rc;

        fibril_mutex_lock(&volumes->lock);
        rc = vol_volume_lookup_ref_locked(volumes, label, rvolume);
        fibril_mutex_unlock(&volumes->lock);

        return rc;
}

/** Determine if volume has non-default settings that need to persist.
 *
 * @param volume Volume
 * @return @c true iff volume has settings that need to persist
 */
static bool vol_volume_is_persist(vol_volume_t *volume)
{
        return str_size(volume->mountp) > 0;
}

/** Delete reference to volume.
 *
 * @param volume Volume
 */
void vol_volume_del_ref(vol_volume_t *volume)
{
        if (refcount_down(&volume->refcnt)) {
                /* No more references. Check if volume is persistent. */
                if (!vol_volume_is_persist(volume)) {
                        list_remove(&volume->lvolumes);
                        vol_volume_delete(volume);
                }
        }
}

/** Set volume mount point.
 *
 * @param volume Volume
 * @param mountp Mount point
 *
 * @return EOK on success or error code
 */
errno_t vol_volume_set_mountp(vol_volume_t *volume, const char *mountp)
{
        char *mp;
        char *old_mp;
        errno_t rc;
        sif_trans_t *trans = NULL;
        sif_node_t *nvolume;

        mp = str_dup(mountp);
        if (mp == NULL)
                return ENOMEM;

        old_mp = volume->mountp;
        volume->mountp = mp;

        if (vol_volume_is_persist(volume)) {
                /* Volume is now persistent */
                if (volume->nvolume == NULL) {
                        /* Create volume node */
                        rc = sif_trans_begin(volume->volumes->repo, &trans);
                        if (rc != EOK)
                                goto error;

                        rc = sif_node_append_child(trans,
                            volume->volumes->nvolumes, "volume", &nvolume);
                        if (rc != EOK)
                                goto error;

                        rc = sif_node_set_attr(trans, nvolume, "label",
                            volume->label);
                        if (rc != EOK)
                                goto error;

                        rc = sif_node_set_attr(trans, nvolume, "mountp",
                            volume->mountp);
                        if (rc != EOK)
                                goto error;

                        rc = sif_trans_end(trans);
                        if (rc != EOK)
                                goto error;

                        trans = NULL;
                        volume->nvolume = nvolume;
                } else {
                        /* Update volume node */
                        rc = sif_trans_begin(volume->volumes->repo, &trans);
                        if (rc != EOK)
                                goto error;

                        rc = sif_node_set_attr(trans, volume->nvolume,
                            "mountp", volume->mountp);
                        if (rc != EOK)
                                goto error;

                        rc = sif_trans_end(trans);
                        if (rc != EOK)
                                goto error;

                        trans = NULL;
                }
        } else {
                /* Volume is now non-persistent */
                if (volume->nvolume != NULL) {
                        /* Delete volume node */
                        rc = sif_trans_begin(volume->volumes->repo, &trans);
                        if (rc != EOK)
                                goto error;

                        sif_node_destroy(trans, volume->nvolume);

                        rc = sif_trans_end(trans);
                        if (rc != EOK)
                                goto error;

                        volume->nvolume = NULL;
                }
        }

        free(old_mp);
        return EOK;
error:
        free(mp);
        volume->mountp = old_mp;

        if (trans != NULL)
                sif_trans_abort(trans);
        return rc;
}

/** Load volumes from SIF repository.
 *
 * @param nvolumes Volumes node
 * @param volumes Volumes object
 *
 * @return EOK on success or error code
 */
static errno_t vol_volumes_load(sif_node_t *nvolumes, vol_volumes_t *volumes)
{
        sif_node_t *nvolume;
        vol_volume_t *volume = NULL;
        const char *label;
        const char *mountp;
        errno_t rc;

        volumes->nvolumes = nvolumes;

        nvolume = sif_node_first_child(nvolumes);
        while (nvolume != NULL) {
                if (str_cmp(sif_node_get_type(nvolume), "volume") != 0) {
                        rc = EIO;
                        goto error;
                }

                volume = vol_volume_new();
                if (volume == NULL) {
                        rc = ENOMEM;
                        goto error;
                }

                label = sif_node_get_attr(nvolume, "label");
                mountp = sif_node_get_attr(nvolume, "mountp");

                if (label == NULL || mountp == NULL) {
                        rc = EIO;
                        goto error;
                }

                free(volume->label);
                free(volume->mountp);

                volume->label = str_dup(label);
                volume->mountp = str_dup(mountp);

                volume->nvolume = nvolume;
                fibril_mutex_lock(&volumes->lock);
                vol_volume_add_locked(volumes, volume);
                fibril_mutex_unlock(&volumes->lock);
                nvolume = sif_node_next_child(nvolume);
        }

        return EOK;
error:
        if (volume != NULL)
                vol_volume_delete(volume);
        return rc;
}

/** @}
 */