// 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;

/*
 * Insert a volume into a cell.  If there's an existing volume record, that is
 * returned instead with a ref held.
 */
static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
                                                      struct afs_volume *volume)
{
        struct afs_volume *p;
        struct rb_node *parent = NULL, **pp;

        write_seqlock(&cell->volume_lock);

        pp = &cell->volumes.rb_node;
        while (*pp) {
                parent = *pp;
                p = rb_entry(parent, struct afs_volume, cell_node);
                if (p->vid < volume->vid) {
                        pp = &(*pp)->rb_left;
                } else if (p->vid > volume->vid) {
                        pp = &(*pp)->rb_right;
                } else {
                        volume = afs_get_volume(p, afs_volume_trace_get_cell_insert);
                        goto found;
                }
        }

        rb_link_node_rcu(&volume->cell_node, parent, pp);
        rb_insert_color(&volume->cell_node, &cell->volumes);
        hlist_add_head_rcu(&volume->proc_link, &cell->proc_volumes);

found:
        write_sequnlock(&cell->volume_lock);
        return volume;

}

static void afs_remove_volume_from_cell(struct afs_volume *volume)
{
        struct afs_cell *cell = volume->cell;

        if (!hlist_unhashed(&volume->proc_link)) {
                trace_afs_volume(volume->vid, atomic_read(&volume->usage),
                                 afs_volume_trace_remove);
                write_seqlock(&cell->volume_lock);
                hlist_del_rcu(&volume->proc_link);
                rb_erase(&volume->cell_node, &cell->volumes);
                write_sequnlock(&cell->volume_lock);
        }
}

/*
 * 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, afs_cell_trace_get_vol);
        volume->type            = params->type;
        volume->type_force      = params->force;
        volume->name_len        = vldb->name_len;

        atomic_set(&volume->usage, 1);
        INIT_HLIST_NODE(&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);
        rcu_assign_pointer(volume->servers, slist);
        trace_afs_volume(volume->vid, 1, afs_volume_trace_alloc);
        return volume;

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

/*
 * Look up or allocate a volume record.
 */
static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
                                            struct afs_vldb_entry *vldb,
                                            unsigned long type_mask)
{
        struct afs_volume *candidate, *volume;

        candidate = afs_alloc_volume(params, vldb, type_mask);
        if (IS_ERR(candidate))
                return candidate;

        volume = afs_insert_volume_into_cell(params->cell, candidate);
        if (volume != candidate)
                afs_put_volume(params->net, candidate, afs_volume_trace_put_cell_dup);
        return volume;
}

/*
 * 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_lookup_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_remove_volume_from_cell(volume);
        afs_put_serverlist(net, rcu_access_pointer(volume->servers));
        afs_put_cell(volume->cell, afs_cell_trace_put_vol);
        trace_afs_volume(volume->vid, atomic_read(&volume->usage),
                         afs_volume_trace_free);
        kfree_rcu(volume, rcu);

        _leave(" [destroyed]");
}

/*
 * Get a reference on a volume record.
 */
struct afs_volume *afs_get_volume(struct afs_volume *volume,
                                  enum afs_volume_trace reason)
{
        if (volume) {
                int u = atomic_inc_return(&volume->usage);
                trace_afs_volume(volume->vid, u, reason);
        }
        return volume;
}


/*
 * Drop a reference on a volume record.
 */
void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
                    enum afs_volume_trace reason)
{
        if (volume) {
                afs_volid_t vid = volume->vid;
                int u = atomic_dec_return(&volume->usage);
                trace_afs_volume(vid, u, reason);
                if (u == 0)
                        afs_destroy_volume(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
}

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

#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 = rcu_dereference_protected(volume->servers,
                                        lockdep_is_held(&volume->servers_lock));
        if (afs_annotate_server_list(new, old)) {
                new->seq = volume->servers_seq + 1;
                rcu_assign_pointer(volume->servers, new);
                smp_wmb();
                volume->servers_seq++;
                discard = old;
        }

        volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
        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 afs_operation *op)
{
        int ret, retries = 0;

        _enter("");

retry:
        if (test_bit(AFS_VOLUME_WAIT, &volume->flags))
                goto wait;
        if (volume->update_at <= ktime_get_real_seconds() ||
            test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags))
                goto update;
        _leave(" = 0");
        return 0;

update:
        if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
                clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
                ret = afs_update_volume_status(volume, op->key);
                if (ret < 0)
                        set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
                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;
        }

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

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

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