// SPDX-License-Identifier: GPL-2.0-or-later
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/* AFS volume management
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*
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* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include "internal.h"
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unsigned __read_mostly afs_volume_gc_delay = 10;
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unsigned __read_mostly afs_volume_record_life = 60 * 60;
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/*
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* Insert a volume into a cell. If there's an existing volume record, that is
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* returned instead with a ref held.
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*/
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static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
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struct afs_volume *volume)
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{
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struct afs_volume *p;
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struct rb_node *parent = NULL, **pp;
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write_seqlock(&cell->volume_lock);
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pp = &cell->volumes.rb_node;
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while (*pp) {
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parent = *pp;
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p = rb_entry(parent, struct afs_volume, cell_node);
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if (p->vid < volume->vid) {
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pp = &(*pp)->rb_left;
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} else if (p->vid > volume->vid) {
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pp = &(*pp)->rb_right;
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} else {
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volume = afs_get_volume(p, afs_volume_trace_get_cell_insert);
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goto found;
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}
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}
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rb_link_node_rcu(&volume->cell_node, parent, pp);
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rb_insert_color(&volume->cell_node, &cell->volumes);
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hlist_add_head_rcu(&volume->proc_link, &cell->proc_volumes);
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found:
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write_sequnlock(&cell->volume_lock);
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return volume;
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}
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static void afs_remove_volume_from_cell(struct afs_volume *volume)
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{
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struct afs_cell *cell = volume->cell;
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if (!hlist_unhashed(&volume->proc_link)) {
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trace_afs_volume(volume->vid, atomic_read(&volume->usage),
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afs_volume_trace_remove);
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write_seqlock(&cell->volume_lock);
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hlist_del_rcu(&volume->proc_link);
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rb_erase(&volume->cell_node, &cell->volumes);
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write_sequnlock(&cell->volume_lock);
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}
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}
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/*
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* Allocate a volume record and load it up from a vldb record.
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*/
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static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
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struct afs_vldb_entry *vldb,
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unsigned long type_mask)
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{
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struct afs_server_list *slist;
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struct afs_volume *volume;
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int ret = -ENOMEM, nr_servers = 0, i;
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for (i = 0; i < vldb->nr_servers; i++)
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if (vldb->fs_mask[i] & type_mask)
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nr_servers++;
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volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
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if (!volume)
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goto error_0;
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volume->vid = vldb->vid[params->type];
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volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
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volume->cell = afs_get_cell(params->cell, afs_cell_trace_get_vol);
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volume->type = params->type;
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volume->type_force = params->force;
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volume->name_len = vldb->name_len;
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atomic_set(&volume->usage, 1);
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INIT_HLIST_NODE(&volume->proc_link);
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rwlock_init(&volume->servers_lock);
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rwlock_init(&volume->cb_v_break_lock);
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memcpy(volume->name, vldb->name, vldb->name_len + 1);
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slist = afs_alloc_server_list(params->cell, params->key, vldb, type_mask);
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if (IS_ERR(slist)) {
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ret = PTR_ERR(slist);
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goto error_1;
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}
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refcount_set(&slist->usage, 1);
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rcu_assign_pointer(volume->servers, slist);
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trace_afs_volume(volume->vid, 1, afs_volume_trace_alloc);
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return volume;
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error_1:
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afs_put_cell(volume->cell, afs_cell_trace_put_vol);
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kfree(volume);
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error_0:
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return ERR_PTR(ret);
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}
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/*
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* Look up or allocate a volume record.
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*/
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static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
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struct afs_vldb_entry *vldb,
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unsigned long type_mask)
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{
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struct afs_volume *candidate, *volume;
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candidate = afs_alloc_volume(params, vldb, type_mask);
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if (IS_ERR(candidate))
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return candidate;
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volume = afs_insert_volume_into_cell(params->cell, candidate);
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if (volume != candidate)
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afs_put_volume(params->net, candidate, afs_volume_trace_put_cell_dup);
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return volume;
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}
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/*
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* Look up a VLDB record for a volume.
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*/
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static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
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struct key *key,
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const char *volname,
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size_t volnamesz)
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{
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struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
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struct afs_vl_cursor vc;
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int ret;
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if (!afs_begin_vlserver_operation(&vc, cell, key))
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return ERR_PTR(-ERESTARTSYS);
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while (afs_select_vlserver(&vc)) {
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vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
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}
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ret = afs_end_vlserver_operation(&vc);
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return ret < 0 ? ERR_PTR(ret) : vldb;
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}
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/*
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* Look up a volume in the VL server and create a candidate volume record for
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* it.
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*
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* The volume name can be one of the following:
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* "%[cell:]volume[.]" R/W volume
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* "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
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* or R/W (rwparent=1) volume
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* "%[cell:]volume.readonly" R/O volume
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* "#[cell:]volume.readonly" R/O volume
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* "%[cell:]volume.backup" Backup volume
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* "#[cell:]volume.backup" Backup volume
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*
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* The cell name is optional, and defaults to the current cell.
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*
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* See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
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* Guide
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* - Rule 1: Explicit type suffix forces access of that type or nothing
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* (no suffix, then use Rule 2 & 3)
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* - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
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* if not available
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* - Rule 3: If parent volume is R/W, then only mount R/W volume unless
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* explicitly told otherwise
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*/
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struct afs_volume *afs_create_volume(struct afs_fs_context *params)
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{
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struct afs_vldb_entry *vldb;
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struct afs_volume *volume;
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unsigned long type_mask = 1UL << params->type;
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vldb = afs_vl_lookup_vldb(params->cell, params->key,
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params->volname, params->volnamesz);
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if (IS_ERR(vldb))
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return ERR_CAST(vldb);
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if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
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volume = ERR_PTR(vldb->error);
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goto error;
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}
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/* Make the final decision on the type we want */
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volume = ERR_PTR(-ENOMEDIUM);
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if (params->force) {
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if (!(vldb->flags & type_mask))
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goto error;
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} else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
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params->type = AFSVL_ROVOL;
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} else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
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params->type = AFSVL_RWVOL;
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} else {
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goto error;
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}
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type_mask = 1UL << params->type;
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volume = afs_lookup_volume(params, vldb, type_mask);
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error:
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kfree(vldb);
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return volume;
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}
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/*
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* Destroy a volume record
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*/
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static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
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{
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_enter("%p", volume);
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#ifdef CONFIG_AFS_FSCACHE
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ASSERTCMP(volume->cache, ==, NULL);
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#endif
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afs_remove_volume_from_cell(volume);
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afs_put_serverlist(net, rcu_access_pointer(volume->servers));
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afs_put_cell(volume->cell, afs_cell_trace_put_vol);
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trace_afs_volume(volume->vid, atomic_read(&volume->usage),
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afs_volume_trace_free);
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kfree_rcu(volume, rcu);
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_leave(" [destroyed]");
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}
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/*
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* Get a reference on a volume record.
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*/
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struct afs_volume *afs_get_volume(struct afs_volume *volume,
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enum afs_volume_trace reason)
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{
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if (volume) {
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int u = atomic_inc_return(&volume->usage);
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trace_afs_volume(volume->vid, u, reason);
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}
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return volume;
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}
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/*
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* Drop a reference on a volume record.
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*/
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void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
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enum afs_volume_trace reason)
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{
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if (volume) {
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afs_volid_t vid = volume->vid;
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int u = atomic_dec_return(&volume->usage);
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trace_afs_volume(vid, u, reason);
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if (u == 0)
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afs_destroy_volume(net, volume);
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}
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}
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/*
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* Activate a volume.
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*/
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void afs_activate_volume(struct afs_volume *volume)
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{
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#ifdef CONFIG_AFS_FSCACHE
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volume->cache = fscache_acquire_cookie(volume->cell->cache,
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&afs_volume_cache_index_def,
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&volume->vid, sizeof(volume->vid),
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NULL, 0,
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volume, 0, true);
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#endif
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}
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/*
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* Deactivate a volume.
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*/
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void afs_deactivate_volume(struct afs_volume *volume)
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{
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_enter("%s", volume->name);
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#ifdef CONFIG_AFS_FSCACHE
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fscache_relinquish_cookie(volume->cache, NULL,
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test_bit(AFS_VOLUME_DELETED, &volume->flags));
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volume->cache = NULL;
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#endif
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_leave("");
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}
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/*
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* Query the VL service to update the volume status.
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*/
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static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
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{
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struct afs_server_list *new, *old, *discard;
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struct afs_vldb_entry *vldb;
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char idbuf[16];
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int ret, idsz;
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_enter("");
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/* We look up an ID by passing it as a decimal string in the
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* operation's name parameter.
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*/
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idsz = sprintf(idbuf, "%llu", volume->vid);
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vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
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if (IS_ERR(vldb)) {
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ret = PTR_ERR(vldb);
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goto error;
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}
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/* See if the volume got renamed. */
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if (vldb->name_len != volume->name_len ||
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memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
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/* TODO: Use RCU'd string. */
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memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
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volume->name_len = vldb->name_len;
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}
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/* See if the volume's server list got updated. */
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new = afs_alloc_server_list(volume->cell, key,
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vldb, (1 << volume->type));
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if (IS_ERR(new)) {
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ret = PTR_ERR(new);
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goto error_vldb;
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}
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write_lock(&volume->servers_lock);
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discard = new;
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old = rcu_dereference_protected(volume->servers,
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lockdep_is_held(&volume->servers_lock));
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if (afs_annotate_server_list(new, old)) {
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new->seq = volume->servers_seq + 1;
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rcu_assign_pointer(volume->servers, new);
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smp_wmb();
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volume->servers_seq++;
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discard = old;
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}
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volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
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write_unlock(&volume->servers_lock);
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ret = 0;
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afs_put_serverlist(volume->cell->net, discard);
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error_vldb:
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kfree(vldb);
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error:
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* Make sure the volume record is up to date.
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*/
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int afs_check_volume_status(struct afs_volume *volume, struct afs_operation *op)
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{
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int ret, retries = 0;
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_enter("");
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retry:
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if (test_bit(AFS_VOLUME_WAIT, &volume->flags))
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goto wait;
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if (volume->update_at <= ktime_get_real_seconds() ||
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test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags))
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goto update;
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_leave(" = 0");
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return 0;
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update:
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if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
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clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
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ret = afs_update_volume_status(volume, op->key);
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if (ret < 0)
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set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
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clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
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clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
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wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
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_leave(" = %d", ret);
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return ret;
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}
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wait:
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if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
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_leave(" = 0 [no wait]");
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return 0;
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}
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ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT,
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(op->flags & AFS_OPERATION_UNINTR) ?
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TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
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if (ret == -ERESTARTSYS) {
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_leave(" = %d", ret);
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return ret;
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}
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retries++;
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if (retries == 4) {
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_leave(" = -ESTALE");
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return -ESTALE;
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}
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goto retry;
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}
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