// 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;

  }