// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS volume management
 *
 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include "internal.h"

unsigned __read_mostly afs_volume_gc_delay = 10;
unsigned __read_mostly afs_volume_record_life = 60 * 60;

static const char *const afs_voltypes[] = { "R/W", "R/O", "BAK" };

/*
 * Allocate a volume record and load it up from a vldb record.
 */
static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
                                           struct afs_vldb_entry *vldb,
                                           unsigned long type_mask)
{
        struct afs_server_list *slist;
        struct afs_volume *volume;
        int ret = -ENOMEM, nr_servers = 0, i;

        for (i = 0; i < vldb->nr_servers; i++)
                if (vldb->fs_mask[i] & type_mask)
                        nr_servers++;

        volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
        if (!volume)
                goto error_0;

        volume->vid             = vldb->vid[params->type];
        volume->update_at       = ktime_get_real_seconds() + afs_volume_record_life;
        volume->cell            = afs_get_cell(params->cell);
        volume->type            = params->type;
        volume->type_force      = params->force;
        volume->name_len        = vldb->name_len;

        atomic_set(&volume->usage, 1);
        INIT_LIST_HEAD(&volume->proc_link);
        rwlock_init(&volume->servers_lock);
        rwlock_init(&volume->cb_v_break_lock);
        memcpy(volume->name, vldb->name, vldb->name_len + 1);

        slist = afs_alloc_server_list(params->cell, params->key, vldb, type_mask);
        if (IS_ERR(slist)) {
                ret = PTR_ERR(slist);
                goto error_1;
        }

        refcount_set(&slist->usage, 1);
        volume->servers = slist;
        return volume;

error_1:
        afs_put_cell(params->net, volume->cell);
        kfree(volume);
error_0:
        return ERR_PTR(ret);
}

/*
 * Look up a VLDB record for a volume.
 */
static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
                                                 struct key *key,
                                                 const char *volname,
                                                 size_t volnamesz)
{
        struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
        struct afs_vl_cursor vc;
        int ret;

        if (!afs_begin_vlserver_operation(&vc, cell, key))
                return ERR_PTR(-ERESTARTSYS);

        while (afs_select_vlserver(&vc)) {
                vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
        }

        ret = afs_end_vlserver_operation(&vc);
        return ret < 0 ? ERR_PTR(ret) : vldb;
}

/*
 * Look up a volume in the VL server and create a candidate volume record for
 * it.
 *
 * The volume name can be one of the following:
 *      "%[cell:]volume[.]"             R/W volume
 *      "#[cell:]volume[.]"             R/O or R/W volume (rwparent=0),
 *                                       or R/W (rwparent=1) volume
 *      "%[cell:]volume.readonly"       R/O volume
 *      "#[cell:]volume.readonly"       R/O volume
 *      "%[cell:]volume.backup"         Backup volume
 *      "#[cell:]volume.backup"         Backup volume
 *
 * The cell name is optional, and defaults to the current cell.
 *
 * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
 * Guide
 * - Rule 1: Explicit type suffix forces access of that type or nothing
 *           (no suffix, then use Rule 2 & 3)
 * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
 *           if not available
 * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
 *           explicitly told otherwise
 */
struct afs_volume *afs_create_volume(struct afs_fs_context *params)
{
        struct afs_vldb_entry *vldb;
        struct afs_volume *volume;
        unsigned long type_mask = 1UL << params->type;

        vldb = afs_vl_lookup_vldb(params->cell, params->key,
                                  params->volname, params->volnamesz);
        if (IS_ERR(vldb))
                return ERR_CAST(vldb);

        if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
                volume = ERR_PTR(vldb->error);
                goto error;
        }

        /* Make the final decision on the type we want */
        volume = ERR_PTR(-ENOMEDIUM);
        if (params->force) {
                if (!(vldb->flags & type_mask))
                        goto error;
        } else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
                params->type = AFSVL_ROVOL;
        } else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
                params->type = AFSVL_RWVOL;
        } else {
                goto error;
        }

        type_mask = 1UL << params->type;
        volume = afs_alloc_volume(params, vldb, type_mask);

error:
        kfree(vldb);
        return volume;
}

/*
 * Destroy a volume record
 */
static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
{
        _enter("%p", volume);

#ifdef CONFIG_AFS_FSCACHE
        ASSERTCMP(volume->cache, ==, NULL);
#endif

        afs_put_serverlist(net, volume->servers);
        afs_put_cell(net, volume->cell);
        kfree(volume);

        _leave(" [destroyed]");
}

/*
 * Drop a reference on a volume record.
 */
void afs_put_volume(struct afs_cell *cell, struct afs_volume *volume)
{
        if (volume) {
                _enter("%s", volume->name);

                if (atomic_dec_and_test(&volume->usage))
                        afs_destroy_volume(cell->net, volume);
        }
}

/*
 * Activate a volume.
 */
void afs_activate_volume(struct afs_volume *volume)
{
#ifdef CONFIG_AFS_FSCACHE
        volume->cache = fscache_acquire_cookie(volume->cell->cache,
                                               &afs_volume_cache_index_def,
                                               &volume->vid, sizeof(volume->vid),
                                               NULL, 0,
                                               volume, 0, true);
#endif

        write_lock(&volume->cell->proc_lock);
        list_add_tail(&volume->proc_link, &volume->cell->proc_volumes);
        write_unlock(&volume->cell->proc_lock);
}

/*
 * Deactivate a volume.
 */
void afs_deactivate_volume(struct afs_volume *volume)
{
        _enter("%s", volume->name);

        write_lock(&volume->cell->proc_lock);
        list_del_init(&volume->proc_link);
        write_unlock(&volume->cell->proc_lock);

#ifdef CONFIG_AFS_FSCACHE
        fscache_relinquish_cookie(volume->cache, NULL,
                                  test_bit(AFS_VOLUME_DELETED, &volume->flags));
        volume->cache = NULL;
#endif

        _leave("");
}

/*
 * Query the VL service to update the volume status.
 */
static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
{
        struct afs_server_list *new, *old, *discard;
        struct afs_vldb_entry *vldb;
        char idbuf[16];
        int ret, idsz;

        _enter("");

        /* We look up an ID by passing it as a decimal string in the
         * operation's name parameter.
         */
        idsz = sprintf(idbuf, "%llu", volume->vid);

        vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
        if (IS_ERR(vldb)) {
                ret = PTR_ERR(vldb);
                goto error;
        }

        /* See if the volume got renamed. */
        if (vldb->name_len != volume->name_len ||
            memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
                /* TODO: Use RCU'd string. */
                memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
                volume->name_len = vldb->name_len;
        }

        /* See if the volume's server list got updated. */
        new = afs_alloc_server_list(volume->cell, key,
                                    vldb, (1 << volume->type));
        if (IS_ERR(new)) {
                ret = PTR_ERR(new);
                goto error_vldb;
        }

        write_lock(&volume->servers_lock);

        discard = new;
        old = volume->servers;
        if (afs_annotate_server_list(new, old)) {
                new->seq = volume->servers_seq + 1;
                volume->servers = new;
                smp_wmb();
                volume->servers_seq++;
                discard = old;
        }

        volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
        clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
        write_unlock(&volume->servers_lock);
        ret = 0;

        afs_put_serverlist(volume->cell->net, discard);
error_vldb:
        kfree(vldb);
error:
        _leave(" = %d", ret);
        return ret;
}

/*
 * Make sure the volume record is up to date.
 */
int afs_check_volume_status(struct afs_volume *volume, struct key *key)
{
        time64_t now = ktime_get_real_seconds();
        int ret, retries = 0;

        _enter("");

        if (volume->update_at <= now)
                set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);

retry:
        if (!test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags) &&
            !test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
                _leave(" = 0");
                return 0;
        }

        if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
                ret = afs_update_volume_status(volume, key);
                clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
                clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
                wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
                _leave(" = %d", ret);
                return ret;
        }

        if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
                _leave(" = 0 [no wait]");
                return 0;
        }

        ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT, TASK_INTERRUPTIBLE);
        if (ret == -ERESTARTSYS) {
                _leave(" = %d", ret);
                return ret;
        }

        retries++;
        if (retries == 4) {
                _leave(" = -ESTALE");
                return -ESTALE;
        }
        goto retry;
}