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// SPDX-License-Identifier: GPL-2.0-or-later/* AFS server record management * * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #include <linux/sched.h>#include <linux/slab.h>#include "afs_fs.h"#include "internal.h"#include "protocol_yfs.h" static unsigned afs_server_gc_delay = 10;	/* Server record timeout in seconds */static atomic_t afs_server_debug_id; static void __afs_put_server(struct afs_net *, struct afs_server *);static void afs_server_timer(struct timer_list *timer);static void afs_server_destroyer(struct work_struct *work); /* * Find a server by one of its addresses. */struct afs_server *afs_find_server(const struct rxrpc_peer *peer){	struct afs_server *server = (struct afs_server *)rxrpc_kernel_get_peer_data(peer); 	if (!server)		return NULL;	return afs_use_server(server, false, afs_server_trace_use_cm_call);} /* * Look up a server by its UUID and mark it active.  The caller must hold * cell->fs_lock. */static struct afs_server *afs_find_server_by_uuid(struct afs_cell *cell, const uuid_t *uuid){	struct afs_server *server;	struct rb_node *p;	int diff; 	_enter("%pU", uuid); 	p = cell->fs_servers.rb_node;	while (p) {		server = rb_entry(p, struct afs_server, uuid_rb); 		diff = memcmp(uuid, &server->uuid, sizeof(*uuid));		if (diff < 0) {			p = p->rb_left;		} else if (diff > 0) {			p = p->rb_right;		} else {			if (test_bit(AFS_SERVER_FL_UNCREATED, &server->flags))				return NULL; /* Need a write lock */			afs_use_server(server, true, afs_server_trace_use_by_uuid);			return server;		}	} 	return NULL;} /* * Install a server record in the cell tree.  The caller must hold an exclusive * lock on cell->fs_lock. */static struct afs_server *afs_install_server(struct afs_cell *cell,					     struct afs_server **candidate){	struct afs_server *server;	struct afs_net *net = cell->net;	struct rb_node **pp, *p;	int diff; 	_enter("%p", candidate); 	/* Firstly install the server in the UUID lookup tree */	pp = &cell->fs_servers.rb_node;	p = NULL;	while (*pp) {		p = *pp;		_debug("- consider %p", p);		server = rb_entry(p, struct afs_server, uuid_rb);		diff = memcmp(&(*candidate)->uuid, &server->uuid, sizeof(uuid_t));		if (diff < 0)			pp = &(*pp)->rb_left;		else if (diff > 0)			pp = &(*pp)->rb_right;		else			goto exists;	} 	server = *candidate;	*candidate = NULL;	rb_link_node(&server->uuid_rb, p, pp);	rb_insert_color(&server->uuid_rb, &cell->fs_servers);	write_seqlock(&net->fs_lock);	hlist_add_head_rcu(&server->proc_link, &net->fs_proc);	write_sequnlock(&net->fs_lock); 	afs_get_cell(cell, afs_cell_trace_get_server); exists:	afs_use_server(server, true, afs_server_trace_use_install);	return server;} /* * Allocate a new server record and mark it as active but uncreated. */static struct afs_server *afs_alloc_server(struct afs_cell *cell, const uuid_t *uuid){	struct afs_server *server;	struct afs_net *net = cell->net; 	_enter(""); 	server = kzalloc_obj(struct afs_server);	if (!server)		return NULL; 	refcount_set(&server->ref, 1);	atomic_set(&server->active, 0);	__set_bit(AFS_SERVER_FL_UNCREATED, &server->flags);	server->debug_id = atomic_inc_return(&afs_server_debug_id);	server->uuid = *uuid;	rwlock_init(&server->fs_lock);	INIT_WORK(&server->destroyer, &afs_server_destroyer);	timer_setup(&server->timer, afs_server_timer, 0);	INIT_LIST_HEAD(&server->volumes);	init_waitqueue_head(&server->probe_wq);	mutex_init(&server->cm_token_lock);	INIT_LIST_HEAD(&server->probe_link);	INIT_HLIST_NODE(&server->proc_link);	spin_lock_init(&server->probe_lock);	server->cell = cell;	server->rtt = UINT_MAX;	server->service_id = FS_SERVICE;	server->probe_counter = 1;	server->probed_at = jiffies - LONG_MAX / 2; 	afs_inc_servers_outstanding(net);	_leave(" = %p", server);	return server;} /* * Look up an address record for a server */static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_server *server,						 struct key *key){	struct afs_vl_cursor vc;	struct afs_addr_list *alist = NULL;	int ret; 	ret = -ERESTARTSYS;	if (afs_begin_vlserver_operation(&vc, server->cell, key)) {		while (afs_select_vlserver(&vc)) {			if (test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags))				alist = afs_yfsvl_get_endpoints(&vc, &server->uuid);			else				alist = afs_vl_get_addrs_u(&vc, &server->uuid);		} 		ret = afs_end_vlserver_operation(&vc);	} 	return ret < 0 ? ERR_PTR(ret) : alist;} /* * Get or create a fileserver record and return it with an active-use count on * it. */struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,				     const uuid_t *uuid, u32 addr_version){	struct afs_addr_list *alist = NULL;	struct afs_server *server, *candidate = NULL;	bool creating = false;	int ret; 	_enter("%p,%pU", cell->net, uuid); 	down_read(&cell->fs_lock);	server = afs_find_server_by_uuid(cell, uuid);	/* Won't see servers marked uncreated. */	up_read(&cell->fs_lock); 	if (server) {		timer_delete_sync(&server->timer);		if (test_bit(AFS_SERVER_FL_CREATING, &server->flags))			goto wait_for_creation;		if (server->addr_version != addr_version)			set_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);		return server;	} 	candidate = afs_alloc_server(cell, uuid);	if (!candidate) {		afs_put_addrlist(alist, afs_alist_trace_put_server_oom);		return ERR_PTR(-ENOMEM);	} 	down_write(&cell->fs_lock);	server = afs_install_server(cell, &candidate);	if (test_bit(AFS_SERVER_FL_CREATING, &server->flags)) {		/* We need to wait for creation to complete. */		up_write(&cell->fs_lock);		goto wait_for_creation;	}	if (test_bit(AFS_SERVER_FL_UNCREATED, &server->flags)) {		set_bit(AFS_SERVER_FL_CREATING, &server->flags);		clear_bit(AFS_SERVER_FL_UNCREATED, &server->flags);		creating = true;	}	up_write(&cell->fs_lock);	timer_delete_sync(&server->timer); 	/* If we get to create the server, we look up the addresses and then	 * immediately dispatch an asynchronous probe to each interface on the	 * fileserver.  This will make sure the repeat-probing service is	 * started.	 */	if (creating) {		alist = afs_vl_lookup_addrs(server, key);		if (IS_ERR(alist)) {			ret = PTR_ERR(alist);			goto create_failed;		} 		ret = afs_fs_probe_fileserver(cell->net, server, alist, key);		if (ret)			goto create_failed; 		clear_and_wake_up_bit(AFS_SERVER_FL_CREATING, &server->flags);	} out:	afs_put_addrlist(alist, afs_alist_trace_put_server_create);	if (candidate) {		kfree(candidate);		afs_dec_servers_outstanding(cell->net);	}	return server ?: ERR_PTR(ret); wait_for_creation:	afs_see_server(server, afs_server_trace_wait_create);	wait_on_bit(&server->flags, AFS_SERVER_FL_CREATING, TASK_UNINTERRUPTIBLE);	if (test_bit_acquire(AFS_SERVER_FL_UNCREATED, &server->flags)) {		/* Barrier: read flag before error */		ret = READ_ONCE(server->create_error);		afs_put_server(cell->net, server, afs_server_trace_unuse_create_fail);		server = NULL;		goto out;	} 	ret = 0;	goto out; create_failed:	down_write(&cell->fs_lock); 	WRITE_ONCE(server->create_error, ret);	smp_wmb(); /* Barrier: set error before flag. */	set_bit(AFS_SERVER_FL_UNCREATED, &server->flags); 	clear_and_wake_up_bit(AFS_SERVER_FL_CREATING, &server->flags); 	if (test_bit(AFS_SERVER_FL_UNCREATED, &server->flags)) {		clear_bit(AFS_SERVER_FL_UNCREATED, &server->flags);		creating = true;	}	afs_unuse_server(cell->net, server, afs_server_trace_unuse_create_fail);	server = NULL; 	up_write(&cell->fs_lock);	goto out;} /* * Set/reduce a server's timer. */static void afs_set_server_timer(struct afs_server *server, unsigned int delay_secs){	mod_timer(&server->timer, jiffies + delay_secs * HZ);} /* * Get a reference on a server object. */struct afs_server *afs_get_server(struct afs_server *server,				  enum afs_server_trace reason){	unsigned int a;	int r; 	__refcount_inc(&server->ref, &r);	a = atomic_read(&server->active);	trace_afs_server(server->debug_id, r + 1, a, reason);	return server;} /* * Get an active count on a server object and maybe remove from the inactive * list. */struct afs_server *afs_use_server(struct afs_server *server, bool activate,				  enum afs_server_trace reason){	unsigned int a;	int r; 	__refcount_inc(&server->ref, &r);	a = atomic_inc_return(&server->active);	if (a == 1 && activate &&	    !test_bit(AFS_SERVER_FL_EXPIRED, &server->flags))		timer_delete(&server->timer); 	trace_afs_server(server->debug_id, r + 1, a, reason);	return server;} /* * Release a reference on a server record. */void afs_put_server(struct afs_net *net, struct afs_server *server,		    enum afs_server_trace reason){	unsigned int a, debug_id;	bool zero;	int r; 	if (!server)		return; 	debug_id = server->debug_id;	a = atomic_read(&server->active);	zero = __refcount_dec_and_test(&server->ref, &r);	trace_afs_server(debug_id, r - 1, a, reason);	if (unlikely(zero))		__afs_put_server(net, server);} /* * Drop an active count on a server object without updating the last-unused * time. */void afs_unuse_server_notime(struct afs_net *net, struct afs_server *server,			     enum afs_server_trace reason){	if (!server)		return; 	if (atomic_dec_and_test(&server->active)) {		if (test_bit(AFS_SERVER_FL_EXPIRED, &server->flags) ||		    READ_ONCE(server->cell->state) >= AFS_CELL_REMOVING)			schedule_work(&server->destroyer);	} 	afs_put_server(net, server, reason);} /* * Drop an active count on a server object. */void afs_unuse_server(struct afs_net *net, struct afs_server *server,		      enum afs_server_trace reason){	if (!server)		return; 	if (atomic_dec_and_test(&server->active)) {		if (!test_bit(AFS_SERVER_FL_EXPIRED, &server->flags) &&		    READ_ONCE(server->cell->state) < AFS_CELL_REMOVING) {			time64_t unuse_time = ktime_get_real_seconds(); 			server->unuse_time = unuse_time;			afs_set_server_timer(server, afs_server_gc_delay);		} else {			schedule_work(&server->destroyer);		}	} 	afs_put_server(net, server, reason);} static void afs_server_rcu(struct rcu_head *rcu){	struct afs_server *server = container_of(rcu, struct afs_server, rcu); 	trace_afs_server(server->debug_id, refcount_read(&server->ref),			 atomic_read(&server->active), afs_server_trace_free);	afs_put_endpoint_state(rcu_access_pointer(server->endpoint_state),			       afs_estate_trace_put_server);	afs_put_cell(server->cell, afs_cell_trace_put_server);	kfree(server->cm_rxgk_appdata.data);	kfree(server);} static void __afs_put_server(struct afs_net *net, struct afs_server *server){	call_rcu(&server->rcu, afs_server_rcu);	afs_dec_servers_outstanding(net);} static void afs_give_up_callbacks(struct afs_net *net, struct afs_server *server){	struct afs_endpoint_state *estate = rcu_access_pointer(server->endpoint_state);	struct afs_addr_list *alist = estate->addresses; 	afs_fs_give_up_all_callbacks(net, server, &alist->addrs[alist->preferred], NULL);} /* * Check to see if the server record has expired. */static bool afs_has_server_expired(const struct afs_server *server){	time64_t expires_at; 	if (atomic_read(&server->active))		return false; 	if (server->cell->net->live ||	    server->cell->state >= AFS_CELL_REMOVING) {		trace_afs_server(server->debug_id, refcount_read(&server->ref),				 0, afs_server_trace_purging);		return true;	} 	expires_at = server->unuse_time;	if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) &&	    !test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags))		expires_at += afs_server_gc_delay; 	return ktime_get_real_seconds() > expires_at;} /* * Remove a server record from it's parent cell's database. */static bool afs_remove_server_from_cell(struct afs_server *server){	struct afs_cell *cell = server->cell; 	down_write(&cell->fs_lock); 	if (!afs_has_server_expired(server)) {		up_write(&cell->fs_lock);		return false;	} 	set_bit(AFS_SERVER_FL_EXPIRED, &server->flags);	_debug("expire %pU %u", &server->uuid, atomic_read(&server->active));	afs_see_server(server, afs_server_trace_see_expired);	rb_erase(&server->uuid_rb, &cell->fs_servers);	up_write(&cell->fs_lock);	return true;} static void afs_server_destroyer(struct work_struct *work){	struct afs_endpoint_state *estate;	struct afs_server *server = container_of(work, struct afs_server, destroyer);	struct afs_net *net = server->cell->net; 	afs_see_server(server, afs_server_trace_see_destroyer); 	if (test_bit(AFS_SERVER_FL_EXPIRED, &server->flags))		return; 	if (!afs_remove_server_from_cell(server))		return; 	timer_shutdown_sync(&server->timer);	cancel_work(&server->destroyer); 	if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))		afs_give_up_callbacks(net, server); 	/* Unbind the rxrpc_peer records from the server. */	estate = rcu_access_pointer(server->endpoint_state);	if (estate)		afs_set_peer_appdata(server, estate->addresses, NULL); 	write_seqlock(&net->fs_lock);	list_del_init(&server->probe_link);	if (!hlist_unhashed(&server->proc_link))		hlist_del_rcu(&server->proc_link);	write_sequnlock(&net->fs_lock); 	afs_put_server(net, server, afs_server_trace_destroy);} static void afs_server_timer(struct timer_list *timer){

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