[linux-2.6-block.git] / fs / afs / rotate.c

/* Handle fileserver selection and rotation.
 *
 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/sched/signal.h>
#include "internal.h"
#include "afs_fs.h"

/*
 * Begin an operation on the fileserver.
 *
 * Fileserver operations are serialised on the server by vnode, so we serialise
 * them here also using the io_lock.
 */
bool afs_begin_vnode_operation(struct afs_fs_cursor *fc, struct afs_vnode *vnode,
			       struct key *key)
{
	memset(fc, 0, sizeof(*fc));
	fc->vnode = vnode;
	fc->key = key;
	fc->ac.error = SHRT_MAX;
	fc->error = -EDESTADDRREQ;

	if (mutex_lock_interruptible(&vnode->io_lock) < 0) {
		fc->error = -EINTR;
		fc->flags |= AFS_FS_CURSOR_STOP;
		return false;
	}

	if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
		fc->flags |= AFS_FS_CURSOR_CUR_ONLY;
	return true;
}

/*
 * Begin iteration through a server list, starting with the vnode's last used
 * server if possible, or the last recorded good server if not.
 */
static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
				   struct afs_vnode *vnode)
{
	struct afs_cb_interest *cbi;
	int i;

	read_lock(&vnode->volume->servers_lock);
	fc->server_list = afs_get_serverlist(vnode->volume->servers);
	read_unlock(&vnode->volume->servers_lock);

	fc->untried = (1UL << fc->server_list->nr_servers) - 1;
	fc->index = READ_ONCE(fc->server_list->preferred);

	cbi = vnode->cb_interest;
	if (cbi) {
		/* See if the vnode's preferred record is still available */
		for (i = 0; i < fc->server_list->nr_servers; i++) {
			if (fc->server_list->servers[i].cb_interest == cbi) {
				fc->index = i;
				goto found_interest;
			}
		}

		/* If we have a lock outstanding on a server that's no longer
		 * serving this vnode, then we can't switch to another server
		 * and have to return an error.
		 */
		if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
			fc->error = -ESTALE;
			return false;
		}

		/* Note that the callback promise is effectively broken */
		write_seqlock(&vnode->cb_lock);
		ASSERTCMP(cbi, ==, vnode->cb_interest);
		vnode->cb_interest = NULL;
		if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
			vnode->cb_break++;
		write_sequnlock(&vnode->cb_lock);

		afs_put_cb_interest(afs_v2net(vnode), cbi);
		cbi = NULL;
	}

found_interest:
	return true;
}

/*
 * Post volume busy note.
 */
static void afs_busy(struct afs_volume *volume, u32 abort_code)
{
	const char *m;

	switch (abort_code) {
	case VOFFLINE:		m = "offline";		break;
	case VRESTARTING:	m = "restarting";	break;
	case VSALVAGING:	m = "being salvaged";	break;
	default:		m = "busy";		break;
	}

	pr_notice("kAFS: Volume %llu '%s' is %s\n", volume->vid, volume->name, m);
}

/*
 * Sleep and retry the operation to the same fileserver.
 */
static bool afs_sleep_and_retry(struct afs_fs_cursor *fc)
{
	msleep_interruptible(1000);
	if (signal_pending(current)) {
		fc->error = -ERESTARTSYS;
		return false;
	}

	return true;
}

/*
 * Select the fileserver to use.  May be called multiple times to rotate
 * through the fileservers.
 */
bool afs_select_fileserver(struct afs_fs_cursor *fc)
{
	struct afs_addr_list *alist;
	struct afs_server *server;
	struct afs_vnode *vnode = fc->vnode;
	struct afs_error e;
	u32 rtt;
	int error = fc->ac.error, i;

	_enter("%lx[%d],%lx[%d],%d,%d",
	       fc->untried, fc->index,
	       fc->ac.tried, fc->ac.index,
	       error, fc->ac.abort_code);

	if (fc->flags & AFS_FS_CURSOR_STOP) {
		_leave(" = f [stopped]");
		return false;
	}

	fc->nr_iterations++;

	/* Evaluate the result of the previous operation, if there was one. */
	switch (error) {
	case SHRT_MAX:
		goto start;

	case 0:
	default:
		/* Success or local failure.  Stop. */
		fc->error = error;
		fc->flags |= AFS_FS_CURSOR_STOP;
		_leave(" = f [okay/local %d]", error);
		return false;

	case -ECONNABORTED:
		/* The far side rejected the operation on some grounds.  This
		 * might involve the server being busy or the volume having been moved.
		 */
		switch (fc->ac.abort_code) {
		case VNOVOL:
			/* This fileserver doesn't know about the volume.
			 * - May indicate that the VL is wrong - retry once and compare
			 *   the results.
			 * - May indicate that the fileserver couldn't attach to the vol.
			 */
			if (fc->flags & AFS_FS_CURSOR_VNOVOL) {
				fc->error = -EREMOTEIO;
				goto next_server;
			}

			write_lock(&vnode->volume->servers_lock);
			fc->server_list->vnovol_mask |= 1 << fc->index;
			write_unlock(&vnode->volume->servers_lock);

			set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
			error = afs_check_volume_status(vnode->volume, fc->key);
			if (error < 0)
				goto failed_set_error;

			if (test_bit(AFS_VOLUME_DELETED, &vnode->volume->flags)) {
				fc->error = -ENOMEDIUM;
				goto failed;
			}

			/* If the server list didn't change, then assume that
			 * it's the fileserver having trouble.
			 */
			if (vnode->volume->servers == fc->server_list) {
				fc->error = -EREMOTEIO;
				goto next_server;
			}

			/* Try again */
			fc->flags |= AFS_FS_CURSOR_VNOVOL;
			_leave(" = t [vnovol]");
			return true;

		case VSALVAGE: /* TODO: Should this return an error or iterate? */
		case VVOLEXISTS:
		case VNOSERVICE:
		case VONLINE:
		case VDISKFULL:
		case VOVERQUOTA:
			fc->error = afs_abort_to_error(fc->ac.abort_code);
			goto next_server;

		case VOFFLINE:
			if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags)) {
				afs_busy(vnode->volume, fc->ac.abort_code);
				clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
			}
			if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
				fc->error = -EADV;
				goto failed;
			}
			if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
				fc->error = -ESTALE;
				goto failed;
			}
			goto busy;

		case VSALVAGING:
		case VRESTARTING:
		case VBUSY:
			/* Retry after going round all the servers unless we
			 * have a file lock we need to maintain.
			 */
			if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
				fc->error = -EBUSY;
				goto failed;
			}
			if (!test_and_set_bit(AFS_VOLUME_BUSY, &vnode->volume->flags)) {
				afs_busy(vnode->volume, fc->ac.abort_code);
				clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
			}
		busy:
			if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
				if (!afs_sleep_and_retry(fc))
					goto failed;

				 /* Retry with same server & address */
				_leave(" = t [vbusy]");
				return true;
			}

			fc->flags |= AFS_FS_CURSOR_VBUSY;
			goto next_server;

		case VMOVED:
			/* The volume migrated to another server.  We consider
			 * consider all locks and callbacks broken and request
			 * an update from the VLDB.
			 *
			 * We also limit the number of VMOVED hops we will
			 * honour, just in case someone sets up a loop.
			 */
			if (fc->flags & AFS_FS_CURSOR_VMOVED) {
				fc->error = -EREMOTEIO;
				goto failed;
			}
			fc->flags |= AFS_FS_CURSOR_VMOVED;

			set_bit(AFS_VOLUME_WAIT, &vnode->volume->flags);
			set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
			error = afs_check_volume_status(vnode->volume, fc->key);
			if (error < 0)
				goto failed_set_error;

			/* If the server list didn't change, then the VLDB is
			 * out of sync with the fileservers.  This is hopefully
			 * a temporary condition, however, so we don't want to
			 * permanently block access to the file.
			 *
			 * TODO: Try other fileservers if we can.
			 *
			 * TODO: Retry a few times with sleeps.
			 */
			if (vnode->volume->servers == fc->server_list) {
				fc->error = -ENOMEDIUM;
				goto failed;
			}

			goto restart_from_beginning;

		default:
			clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
			clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
			fc->error = afs_abort_to_error(fc->ac.abort_code);
			goto failed;
		}

	case -ETIMEDOUT:
	case -ETIME:
		if (fc->error != -EDESTADDRREQ)
			goto iterate_address;
		/* Fall through */
	case -ERFKILL:
	case -EADDRNOTAVAIL:
	case -ENETUNREACH:
	case -EHOSTUNREACH:
	case -EHOSTDOWN:
	case -ECONNREFUSED:
		_debug("no conn");
		fc->error = error;
		goto iterate_address;

	case -ECONNRESET:
		_debug("call reset");
		fc->error = error;
		goto failed;
	}

restart_from_beginning:
	_debug("restart");
	afs_end_cursor(&fc->ac);
	afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
	fc->cbi = NULL;
	afs_put_serverlist(afs_v2net(vnode), fc->server_list);
	fc->server_list = NULL;
start:
	_debug("start");
	/* See if we need to do an update of the volume record.  Note that the
	 * volume may have moved or even have been deleted.
	 */
	error = afs_check_volume_status(vnode->volume, fc->key);
	if (error < 0)
		goto failed_set_error;

	if (!afs_start_fs_iteration(fc, vnode))
		goto failed;

	_debug("__ VOL %llx __", vnode->volume->vid);
	error = afs_probe_fileservers(afs_v2net(vnode), fc->key, fc->server_list);
	if (error < 0)
		goto failed_set_error;

pick_server:
	_debug("pick [%lx]", fc->untried);

	error = afs_wait_for_fs_probes(fc->server_list, fc->untried);
	if (error < 0)
		goto failed_set_error;

	/* Pick the untried server with the lowest RTT.  If we have outstanding
	 * callbacks, we stick with the server we're already using if we can.
	 */
	if (fc->cbi) {
		_debug("cbi %u", fc->index);
		if (test_bit(fc->index, &fc->untried))
			goto selected_server;
		afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
		fc->cbi = NULL;
		_debug("nocbi");
	}

	fc->index = -1;
	rtt = U32_MAX;
	for (i = 0; i < fc->server_list->nr_servers; i++) {
		struct afs_server *s = fc->server_list->servers[i].server;

		if (!test_bit(i, &fc->untried) || !s->probe.responded)
			continue;
		if (s->probe.rtt < rtt) {
			fc->index = i;
			rtt = s->probe.rtt;
		}
	}

	if (fc->index == -1)
		goto no_more_servers;

selected_server:
	_debug("use %d", fc->index);
	__clear_bit(fc->index, &fc->untried);

	/* We're starting on a different fileserver from the list.  We need to
	 * check it, create a callback intercept, find its address list and
	 * probe its capabilities before we use it.
	 */
	ASSERTCMP(fc->ac.alist, ==, NULL);
	server = fc->server_list->servers[fc->index].server;

	if (!afs_check_server_record(fc, server))
		goto failed;

	_debug("USING SERVER: %pU", &server->uuid);

	/* Make sure we've got a callback interest record for this server.  We
	 * have to link it in before we send the request as we can be sent a
	 * break request before we've finished decoding the reply and
	 * installing the vnode.
	 */
	error = afs_register_server_cb_interest(vnode, fc->server_list,
						fc->index);
	if (error < 0)
		goto failed_set_error;

	fc->cbi = afs_get_cb_interest(vnode->cb_interest);

	read_lock(&server->fs_lock);
	alist = rcu_dereference_protected(server->addresses,
					  lockdep_is_held(&server->fs_lock));
	afs_get_addrlist(alist);
	read_unlock(&server->fs_lock);

	memset(&fc->ac, 0, sizeof(fc->ac));

	if (!fc->ac.alist)
		fc->ac.alist = alist;
	else
		afs_put_addrlist(alist);

	fc->ac.index = -1;

iterate_address:
	ASSERT(fc->ac.alist);
	/* Iterate over the current server's address list to try and find an
	 * address on which it will respond to us.
	 */
	if (!afs_iterate_addresses(&fc->ac))
		goto next_server;

	_debug("address [%u] %u/%u", fc->index, fc->ac.index, fc->ac.alist->nr_addrs);

	_leave(" = t");
	return true;

next_server:
	_debug("next");
	afs_end_cursor(&fc->ac);
	goto pick_server;

no_more_servers:
	/* That's all the servers poked to no good effect.  Try again if some
	 * of them were busy.
	 */
	if (fc->flags & AFS_FS_CURSOR_VBUSY)
		goto restart_from_beginning;

	e.error = -EDESTADDRREQ;
	e.responded = false;
	for (i = 0; i < fc->server_list->nr_servers; i++) {
		struct afs_server *s = fc->server_list->servers[i].server;

		afs_prioritise_error(&e, READ_ONCE(s->probe.error),
				     s->probe.abort_code);
	}

failed_set_error:
	fc->error = error;
failed:
	fc->flags |= AFS_FS_CURSOR_STOP;
	afs_end_cursor(&fc->ac);
	_leave(" = f [failed %d]", fc->error);
	return false;
}

/*
 * Select the same fileserver we used for a vnode before and only that
 * fileserver.  We use this when we have a lock on that file, which is backed
 * only by the fileserver we obtained it from.
 */
bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
{
	struct afs_vnode *vnode = fc->vnode;
	struct afs_cb_interest *cbi = vnode->cb_interest;
	struct afs_addr_list *alist;
	int error = fc->ac.error;

	_enter("");

	switch (error) {
	case SHRT_MAX:
		if (!cbi) {
			fc->error = -ESTALE;
			fc->flags |= AFS_FS_CURSOR_STOP;
			return false;
		}

		fc->cbi = afs_get_cb_interest(vnode->cb_interest);

		read_lock(&cbi->server->fs_lock);
		alist = rcu_dereference_protected(cbi->server->addresses,
						  lockdep_is_held(&cbi->server->fs_lock));
		afs_get_addrlist(alist);
		read_unlock(&cbi->server->fs_lock);
		if (!alist) {
			fc->error = -ESTALE;
			fc->flags |= AFS_FS_CURSOR_STOP;
			return false;
		}

		memset(&fc->ac, 0, sizeof(fc->ac));
		fc->ac.alist = alist;
		fc->ac.index = -1;
		goto iterate_address;

	case 0:
	default:
		/* Success or local failure.  Stop. */
		fc->error = error;
		fc->flags |= AFS_FS_CURSOR_STOP;
		_leave(" = f [okay/local %d]", error);
		return false;

	case -ECONNABORTED:
		fc->error = afs_abort_to_error(fc->ac.abort_code);
		fc->flags |= AFS_FS_CURSOR_STOP;
		_leave(" = f [abort]");
		return false;

	case -ERFKILL:
	case -EADDRNOTAVAIL:
	case -ENETUNREACH:
	case -EHOSTUNREACH:
	case -EHOSTDOWN:
	case -ECONNREFUSED:
	case -ETIMEDOUT:
	case -ETIME:
		_debug("no conn");
		fc->error = error;
		goto iterate_address;
	}

iterate_address:
	/* Iterate over the current server's address list to try and find an
	 * address on which it will respond to us.
	 */
	if (afs_iterate_addresses(&fc->ac)) {
		_leave(" = t");
		return true;
	}

	afs_end_cursor(&fc->ac);
	return false;
}

/*
 * Dump cursor state in the case of the error being EDESTADDRREQ.
 */
static void afs_dump_edestaddrreq(const struct afs_fs_cursor *fc)
{
	static int count;
	int i;

	if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)
		return;
	count++;

	rcu_read_lock();

	pr_notice("EDESTADDR occurred\n");
	pr_notice("FC: cbb=%x cbb2=%x fl=%hx err=%hd\n",
		  fc->cb_break, fc->cb_break_2, fc->flags, fc->error);
	pr_notice("FC: ut=%lx ix=%d ni=%u\n",
		  fc->untried, fc->index, fc->nr_iterations);

	if (fc->server_list) {
		const struct afs_server_list *sl = fc->server_list;
		pr_notice("FC: SL nr=%u pr=%u vnov=%hx\n",
			  sl->nr_servers, sl->preferred, sl->vnovol_mask);
		for (i = 0; i < sl->nr_servers; i++) {
			const struct afs_server *s = sl->servers[i].server;
			pr_notice("FC: server fl=%lx av=%u %pU\n",
				  s->flags, s->addr_version, &s->uuid);
			if (s->addresses) {
				const struct afs_addr_list *a =
					rcu_dereference(s->addresses);
				pr_notice("FC:  - av=%u nr=%u/%u/%u pr=%u\n",
					  a->version,
					  a->nr_ipv4, a->nr_addrs, a->max_addrs,
					  a->preferred);
				pr_notice("FC:  - pr=%lx R=%lx F=%lx\n",
					  a->probed, a->responded, a->failed);
				if (a == fc->ac.alist)
					pr_notice("FC:  - current\n");
			}
		}
	}

	pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
		  fc->ac.tried, fc->ac.index, fc->ac.abort_code, fc->ac.error,
		  fc->ac.responded, fc->ac.nr_iterations);
	rcu_read_unlock();
}

/*
 * Tidy up a filesystem cursor and unlock the vnode.
 */
int afs_end_vnode_operation(struct afs_fs_cursor *fc)
{
	struct afs_net *net = afs_v2net(fc->vnode);

	if (fc->error == -EDESTADDRREQ ||
	    fc->error == -EADDRNOTAVAIL ||
	    fc->error == -ENETUNREACH ||
	    fc->error == -EHOSTUNREACH)
		afs_dump_edestaddrreq(fc);

	mutex_unlock(&fc->vnode->io_lock);

	afs_end_cursor(&fc->ac);
	afs_put_cb_interest(net, fc->cbi);
	afs_put_serverlist(net, fc->server_list);

	if (fc->error == -ECONNABORTED)
		fc->error = afs_abort_to_error(fc->ac.abort_code);

	return fc->error;
}
Commit	Line	Data
9cc6fc50 DH	1	/* Handle fileserver selection and rotation.
	2	*
	3	* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/kernel.h>
	13	#include <linux/slab.h>
d2ddc776 DH	14	#include <linux/fs.h>
	15	#include <linux/sched.h>
	16	#include <linux/delay.h>
	17	#include <linux/sched/signal.h>
9cc6fc50	18	#include "internal.h"
d2ddc776	19	#include "afs_fs.h"
9cc6fc50	20
d2ddc776 DH	21	/*
	22	* Begin an operation on the fileserver.
	23	*
	24	* Fileserver operations are serialised on the server by vnode, so we serialise
	25	* them here also using the io_lock.
	26	*/
	27	bool afs_begin_vnode_operation(struct afs_fs_cursor fc, struct afs_vnode vnode,
	28	struct key *key)
	29	{
3bf0fb6f	30	memset(fc, 0, sizeof(*fc));
d2ddc776 DH	31	fc->vnode = vnode;
	32	fc->key = key;
	33	fc->ac.error = SHRT_MAX;
e7f680f4	34	fc->error = -EDESTADDRREQ;
d2ddc776 DH	35
d2ddc776 DH	36	if (mutex_lock_interruptible(&vnode->io_lock) < 0) {
e7f680f4	37	fc->error = -EINTR;
d2ddc776 DH	38	fc->flags \|= AFS_FS_CURSOR_STOP;
	39	return false;
	40	}
	41
0fafdc9f	42	if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
d2ddc776 DH	43	fc->flags \|= AFS_FS_CURSOR_CUR_ONLY;
	44	return true;
	45	}
	46
	47	/*
	48	* Begin iteration through a server list, starting with the vnode's last used
	49	* server if possible, or the last recorded good server if not.
	50	*/
	51	static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
	52	struct afs_vnode *vnode)
	53	{
	54	struct afs_cb_interest *cbi;
	55	int i;
	56
	57	read_lock(&vnode->volume->servers_lock);
	58	fc->server_list = afs_get_serverlist(vnode->volume->servers);
	59	read_unlock(&vnode->volume->servers_lock);
	60
3bf0fb6f DH	61	fc->untried = (1UL << fc->server_list->nr_servers) - 1;
	62	fc->index = READ_ONCE(fc->server_list->preferred);
	63
d2ddc776 DH	64	cbi = vnode->cb_interest;
	65	if (cbi) {
	66	/* See if the vnode's preferred record is still available */
	67	for (i = 0; i < fc->server_list->nr_servers; i++) {
	68	if (fc->server_list->servers[i].cb_interest == cbi) {
3bf0fb6f	69	fc->index = i;
d2ddc776 DH	70	goto found_interest;
	71	}
	72	}
	73
	74	/* If we have a lock outstanding on a server that's no longer
	75	* serving this vnode, then we can't switch to another server
	76	* and have to return an error.
	77	*/
	78	if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
e7f680f4	79	fc->error = -ESTALE;
d2ddc776 DH	80	return false;
	81	}
	82
	83	/* Note that the callback promise is effectively broken */
	84	write_seqlock(&vnode->cb_lock);
	85	ASSERTCMP(cbi, ==, vnode->cb_interest);
	86	vnode->cb_interest = NULL;
	87	if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
	88	vnode->cb_break++;
	89	write_sequnlock(&vnode->cb_lock);
	90
	91	afs_put_cb_interest(afs_v2net(vnode), cbi);
	92	cbi = NULL;
d2ddc776 DH	93	}
	94
	95	found_interest:
d2ddc776 DH	96	return true;
	97	}
	98
	99	/*
	100	* Post volume busy note.
	101	*/
	102	static void afs_busy(struct afs_volume *volume, u32 abort_code)
	103	{
	104	const char *m;
	105
	106	switch (abort_code) {
	107	case VOFFLINE: m = "offline"; break;
	108	case VRESTARTING: m = "restarting"; break;
	109	case VSALVAGING: m = "being salvaged"; break;
	110	default: m = "busy"; break;
	111	}
0fafdc9f	112
3b6492df	113	pr_notice("kAFS: Volume %llu '%s' is %s\n", volume->vid, volume->name, m);
d2ddc776 DH	114	}
	115
	116	/*
	117	* Sleep and retry the operation to the same fileserver.
	118	*/
	119	static bool afs_sleep_and_retry(struct afs_fs_cursor *fc)
	120	{
	121	msleep_interruptible(1000);
	122	if (signal_pending(current)) {
e7f680f4	123	fc->error = -ERESTARTSYS;
d2ddc776 DH	124	return false;
	125	}
	126
	127	return true;
	128	}
	129
	130	/*
	131	* Select the fileserver to use. May be called multiple times to rotate
	132	* through the fileservers.
	133	*/
	134	bool afs_select_fileserver(struct afs_fs_cursor *fc)
	135	{
	136	struct afs_addr_list *alist;
	137	struct afs_server *server;
	138	struct afs_vnode *vnode = fc->vnode;
4584ae96 DH	139	struct afs_error e;
4584ae96 DH	140	u32 rtt;
3bf0fb6f	141	int error = fc->ac.error, i;
d2ddc776	142
3bf0fb6f DH	143	_enter("%lx[%d],%lx[%d],%d,%d",
	144	fc->untried, fc->index,
	145	fc->ac.tried, fc->ac.index,
e7f680f4	146	error, fc->ac.abort_code);
d2ddc776 DH	147
	148	if (fc->flags & AFS_FS_CURSOR_STOP) {
	149	_leave(" = f [stopped]");
	150	return false;
	151	}
	152
744bcd71 DH	153	fc->nr_iterations++;
744bcd71 DH	154
d2ddc776	155	/* Evaluate the result of the previous operation, if there was one. */
e7f680f4	156	switch (error) {
d2ddc776 DH	157	case SHRT_MAX:
	158	goto start;
	159
	160	case 0:
	161	default:
	162	/* Success or local failure. Stop. */
e7f680f4	163	fc->error = error;
d2ddc776	164	fc->flags \|= AFS_FS_CURSOR_STOP;
e7f680f4	165	_leave(" = f [okay/local %d]", error);
d2ddc776 DH	166	return false;
	167
	168	case -ECONNABORTED:
	169	/* The far side rejected the operation on some grounds. This
	170	* might involve the server being busy or the volume having been moved.
	171	*/
	172	switch (fc->ac.abort_code) {
	173	case VNOVOL:
	174	/* This fileserver doesn't know about the volume.
	175	* - May indicate that the VL is wrong - retry once and compare
	176	* the results.
	177	* - May indicate that the fileserver couldn't attach to the vol.
	178	*/
	179	if (fc->flags & AFS_FS_CURSOR_VNOVOL) {
e7f680f4	180	fc->error = -EREMOTEIO;
3d9fa911	181	goto next_server;
d2ddc776 DH	182	}
	183
	184	write_lock(&vnode->volume->servers_lock);
	185	fc->server_list->vnovol_mask \|= 1 << fc->index;
	186	write_unlock(&vnode->volume->servers_lock);
	187
	188	set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
e7f680f4 DH	189	error = afs_check_volume_status(vnode->volume, fc->key);
	190	if (error < 0)
	191	goto failed_set_error;
d2ddc776 DH	192
d2ddc776 DH	193	if (test_bit(AFS_VOLUME_DELETED, &vnode->volume->flags)) {
e7f680f4	194	fc->error = -ENOMEDIUM;
d2ddc776 DH	195	goto failed;
	196	}
	197
	198	/* If the server list didn't change, then assume that
	199	* it's the fileserver having trouble.
	200	*/
	201	if (vnode->volume->servers == fc->server_list) {
e7f680f4	202	fc->error = -EREMOTEIO;
3d9fa911	203	goto next_server;
d2ddc776 DH	204	}
	205
	206	/* Try again */
	207	fc->flags \|= AFS_FS_CURSOR_VNOVOL;
	208	_leave(" = t [vnovol]");
	209	return true;
	210
	211	case VSALVAGE: /* TODO: Should this return an error or iterate? */
	212	case VVOLEXISTS:
	213	case VNOSERVICE:
	214	case VONLINE:
	215	case VDISKFULL:
	216	case VOVERQUOTA:
e7f680f4	217	fc->error = afs_abort_to_error(fc->ac.abort_code);
d2ddc776 DH	218	goto next_server;
	219
	220	case VOFFLINE:
	221	if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags)) {
	222	afs_busy(vnode->volume, fc->ac.abort_code);
	223	clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
	224	}
	225	if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
e7f680f4	226	fc->error = -EADV;
d2ddc776 DH	227	goto failed;
	228	}
	229	if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
e7f680f4	230	fc->error = -ESTALE;
d2ddc776 DH	231	goto failed;
	232	}
	233	goto busy;
	234
	235	case VSALVAGING:
	236	case VRESTARTING:
	237	case VBUSY:
	238	/* Retry after going round all the servers unless we
	239	* have a file lock we need to maintain.
	240	*/
	241	if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
e7f680f4	242	fc->error = -EBUSY;
d2ddc776 DH	243	goto failed;
	244	}
	245	if (!test_and_set_bit(AFS_VOLUME_BUSY, &vnode->volume->flags)) {
	246	afs_busy(vnode->volume, fc->ac.abort_code);
	247	clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
	248	}
	249	busy:
	250	if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
	251	if (!afs_sleep_and_retry(fc))
	252	goto failed;
	253
	254	/* Retry with same server & address */
	255	_leave(" = t [vbusy]");
	256	return true;
	257	}
	258
	259	fc->flags \|= AFS_FS_CURSOR_VBUSY;
	260	goto next_server;
	261
	262	case VMOVED:
	263	/* The volume migrated to another server. We consider
	264	* consider all locks and callbacks broken and request
	265	* an update from the VLDB.
	266	*
	267	* We also limit the number of VMOVED hops we will
	268	* honour, just in case someone sets up a loop.
	269	*/
	270	if (fc->flags & AFS_FS_CURSOR_VMOVED) {
e7f680f4	271	fc->error = -EREMOTEIO;
d2ddc776 DH	272	goto failed;
	273	}
	274	fc->flags \|= AFS_FS_CURSOR_VMOVED;
	275
	276	set_bit(AFS_VOLUME_WAIT, &vnode->volume->flags);
	277	set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
e7f680f4 DH	278	error = afs_check_volume_status(vnode->volume, fc->key);
	279	if (error < 0)
	280	goto failed_set_error;
d2ddc776 DH	281
	282	/* If the server list didn't change, then the VLDB is
	283	* out of sync with the fileservers. This is hopefully
	284	* a temporary condition, however, so we don't want to
	285	* permanently block access to the file.
	286	*
	287	* TODO: Try other fileservers if we can.
	288	*
	289	* TODO: Retry a few times with sleeps.
	290	*/
	291	if (vnode->volume->servers == fc->server_list) {
e7f680f4	292	fc->error = -ENOMEDIUM;
d2ddc776 DH	293	goto failed;
	294	}
	295
	296	goto restart_from_beginning;
	297
	298	default:
	299	clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
	300	clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
e7f680f4	301	fc->error = afs_abort_to_error(fc->ac.abort_code);
d2ddc776 DH	302	goto failed;
	303	}
	304
e7f680f4 DH	305	case -ETIMEDOUT:
	306	case -ETIME:
	307	if (fc->error != -EDESTADDRREQ)
	308	goto iterate_address;
	309	/* Fall through */
4584ae96 DH	310	case -ERFKILL:
4584ae96 DH	311	case -EADDRNOTAVAIL:
d2ddc776 DH	312	case -ENETUNREACH:
d2ddc776 DH	313	case -EHOSTUNREACH:
4584ae96	314	case -EHOSTDOWN:
d2ddc776	315	case -ECONNREFUSED:
d2ddc776	316	_debug("no conn");
e7f680f4	317	fc->error = error;
d2ddc776	318	goto iterate_address;
1a025028 DH	319
	320	case -ECONNRESET:
	321	_debug("call reset");
e7f680f4	322	fc->error = error;
1a025028	323	goto failed;
d2ddc776 DH	324	}
	325
	326	restart_from_beginning:
	327	_debug("restart");
	328	afs_end_cursor(&fc->ac);
	329	afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
	330	fc->cbi = NULL;
	331	afs_put_serverlist(afs_v2net(vnode), fc->server_list);
	332	fc->server_list = NULL;
	333	start:
	334	_debug("start");
	335	/* See if we need to do an update of the volume record. Note that the
	336	* volume may have moved or even have been deleted.
	337	*/
e7f680f4 DH	338	error = afs_check_volume_status(vnode->volume, fc->key);
	339	if (error < 0)
	340	goto failed_set_error;
d2ddc776 DH	341
	342	if (!afs_start_fs_iteration(fc, vnode))
	343	goto failed;
d2ddc776	344
3bf0fb6f DH	345	_debug("__ VOL %llx __", vnode->volume->vid);
	346	error = afs_probe_fileservers(afs_v2net(vnode), fc->key, fc->server_list);
	347	if (error < 0)
	348	goto failed_set_error;
	349
	350	pick_server:
	351	_debug("pick [%lx]", fc->untried);
	352
	353	error = afs_wait_for_fs_probes(fc->server_list, fc->untried);
	354	if (error < 0)
	355	goto failed_set_error;
	356
	357	/* Pick the untried server with the lowest RTT. If we have outstanding
	358	* callbacks, we stick with the server we're already using if we can.
	359	*/
	360	if (fc->cbi) {
	361	_debug("cbi %u", fc->index);
	362	if (test_bit(fc->index, &fc->untried))
	363	goto selected_server;
	364	afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
	365	fc->cbi = NULL;
	366	_debug("nocbi");
	367	}
	368
	369	fc->index = -1;
	370	rtt = U32_MAX;
	371	for (i = 0; i < fc->server_list->nr_servers; i++) {
	372	struct afs_server *s = fc->server_list->servers[i].server;
	373
	374	if (!test_bit(i, &fc->untried) \|\| !s->probe.responded)
	375	continue;
	376	if (s->probe.rtt < rtt) {
	377	fc->index = i;
	378	rtt = s->probe.rtt;
	379	}
	380	}
	381
	382	if (fc->index == -1)
	383	goto no_more_servers;
	384
	385	selected_server:
	386	_debug("use %d", fc->index);
	387	__clear_bit(fc->index, &fc->untried);
	388
d2ddc776 DH	389	/* We're starting on a different fileserver from the list. We need to
	390	* check it, create a callback intercept, find its address list and
	391	* probe its capabilities before we use it.
	392	*/
	393	ASSERTCMP(fc->ac.alist, ==, NULL);
	394	server = fc->server_list->servers[fc->index].server;
	395
	396	if (!afs_check_server_record(fc, server))
	397	goto failed;
	398
	399	_debug("USING SERVER: %pU", &server->uuid);
	400
	401	/* Make sure we've got a callback interest record for this server. We
	402	* have to link it in before we send the request as we can be sent a
	403	* break request before we've finished decoding the reply and
	404	* installing the vnode.
	405	*/
e7f680f4 DH	406	error = afs_register_server_cb_interest(vnode, fc->server_list,
	407	fc->index);
	408	if (error < 0)
	409	goto failed_set_error;
d2ddc776 DH	410
	411	fc->cbi = afs_get_cb_interest(vnode->cb_interest);
	412
	413	read_lock(&server->fs_lock);
	414	alist = rcu_dereference_protected(server->addresses,
	415	lockdep_is_held(&server->fs_lock));
	416	afs_get_addrlist(alist);
	417	read_unlock(&server->fs_lock);
	418
8305e579	419	memset(&fc->ac, 0, sizeof(fc->ac));
d2ddc776	420
d2ddc776 DH	421	if (!fc->ac.alist)
	422	fc->ac.alist = alist;
	423	else
	424	afs_put_addrlist(alist);
	425
3bf0fb6f	426	fc->ac.index = -1;
d2ddc776 DH	427
	428	iterate_address:
	429	ASSERT(fc->ac.alist);
d2ddc776 DH	430	/* Iterate over the current server's address list to try and find an
	431	* address on which it will respond to us.
	432	*/
fe4d774c DH	433	if (!afs_iterate_addresses(&fc->ac))
fe4d774c DH	434	goto next_server;
d2ddc776	435
3bf0fb6f DH	436	_debug("address [%u] %u/%u", fc->index, fc->ac.index, fc->ac.alist->nr_addrs);
3bf0fb6f DH	437
fe4d774c DH	438	_leave(" = t");
fe4d774c DH	439	return true;
d2ddc776	440
16280a15 DH	441	next_server:
	442	_debug("next");
	443	afs_end_cursor(&fc->ac);
3bf0fb6f	444	goto pick_server;
16280a15	445
3bf0fb6f	446	no_more_servers:
16280a15 DH	447	/* That's all the servers poked to no good effect. Try again if some
	448	* of them were busy.
	449	*/
	450	if (fc->flags & AFS_FS_CURSOR_VBUSY)
	451	goto restart_from_beginning;
	452
4584ae96 DH	453	e.error = -EDESTADDRREQ;
4584ae96 DH	454	e.responded = false;
3bf0fb6f DH	455	for (i = 0; i < fc->server_list->nr_servers; i++) {
3bf0fb6f DH	456	struct afs_server *s = fc->server_list->servers[i].server;
3bf0fb6f	457
4584ae96 DH	458	afs_prioritise_error(&e, READ_ONCE(s->probe.error),
4584ae96 DH	459	s->probe.abort_code);
3bf0fb6f DH	460	}
3bf0fb6f DH	461
e7f680f4 DH	462	failed_set_error:
e7f680f4 DH	463	fc->error = error;
d2ddc776 DH	464	failed:
d2ddc776 DH	465	fc->flags \|= AFS_FS_CURSOR_STOP;
fe4d774c	466	afs_end_cursor(&fc->ac);
e7f680f4	467	_leave(" = f [failed %d]", fc->error);
d2ddc776 DH	468	return false;
	469	}
	470
	471	/*
	472	* Select the same fileserver we used for a vnode before and only that
	473	* fileserver. We use this when we have a lock on that file, which is backed
	474	* only by the fileserver we obtained it from.
	475	*/
	476	bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
	477	{
	478	struct afs_vnode *vnode = fc->vnode;
	479	struct afs_cb_interest *cbi = vnode->cb_interest;
	480	struct afs_addr_list *alist;
e7f680f4	481	int error = fc->ac.error;
d2ddc776 DH	482
	483	_enter("");
	484
e7f680f4	485	switch (error) {
0fafdc9f DH	486	case SHRT_MAX:
0fafdc9f DH	487	if (!cbi) {
e7f680f4	488	fc->error = -ESTALE;
0fafdc9f DH	489	fc->flags \|= AFS_FS_CURSOR_STOP;
	490	return false;
	491	}
	492
	493	fc->cbi = afs_get_cb_interest(vnode->cb_interest);
	494
	495	read_lock(&cbi->server->fs_lock);
	496	alist = rcu_dereference_protected(cbi->server->addresses,
	497	lockdep_is_held(&cbi->server->fs_lock));
	498	afs_get_addrlist(alist);
	499	read_unlock(&cbi->server->fs_lock);
	500	if (!alist) {
e7f680f4	501	fc->error = -ESTALE;
0fafdc9f DH	502	fc->flags \|= AFS_FS_CURSOR_STOP;
	503	return false;
	504	}
	505
8305e579	506	memset(&fc->ac, 0, sizeof(fc->ac));
0fafdc9f	507	fc->ac.alist = alist;
3bf0fb6f	508	fc->ac.index = -1;
0fafdc9f DH	509	goto iterate_address;
	510
	511	case 0:
	512	default:
	513	/* Success or local failure. Stop. */
e7f680f4	514	fc->error = error;
d2ddc776	515	fc->flags \|= AFS_FS_CURSOR_STOP;
e7f680f4	516	_leave(" = f [okay/local %d]", error);
d2ddc776	517	return false;
d2ddc776	518
0fafdc9f	519	case -ECONNABORTED:
e7f680f4	520	fc->error = afs_abort_to_error(fc->ac.abort_code);
d2ddc776	521	fc->flags \|= AFS_FS_CURSOR_STOP;
0fafdc9f	522	_leave(" = f [abort]");
d2ddc776	523	return false;
0fafdc9f	524
4584ae96 DH	525	case -ERFKILL:
4584ae96 DH	526	case -EADDRNOTAVAIL:
0fafdc9f DH	527	case -ENETUNREACH:
0fafdc9f DH	528	case -EHOSTUNREACH:
4584ae96	529	case -EHOSTDOWN:
0fafdc9f DH	530	case -ECONNREFUSED:
	531	case -ETIMEDOUT:
	532	case -ETIME:
	533	_debug("no conn");
e7f680f4	534	fc->error = error;
0fafdc9f	535	goto iterate_address;
d2ddc776 DH	536	}
d2ddc776 DH	537
0fafdc9f DH	538	iterate_address:
	539	/* Iterate over the current server's address list to try and find an
	540	* address on which it will respond to us.
	541	*/
	542	if (afs_iterate_addresses(&fc->ac)) {
	543	_leave(" = t");
	544	return true;
	545	}
	546
	547	afs_end_cursor(&fc->ac);
	548	return false;
d2ddc776 DH	549	}
d2ddc776 DH	550
744bcd71 DH	551	/*
	552	* Dump cursor state in the case of the error being EDESTADDRREQ.
	553	*/
	554	static void afs_dump_edestaddrreq(const struct afs_fs_cursor *fc)
	555	{
	556	static int count;
	557	int i;
	558
	559	if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) \|\| count > 3)
	560	return;
	561	count++;
	562
	563	rcu_read_lock();
	564
	565	pr_notice("EDESTADDR occurred\n");
	566	pr_notice("FC: cbb=%x cbb2=%x fl=%hx err=%hd\n",
	567	fc->cb_break, fc->cb_break_2, fc->flags, fc->error);
3bf0fb6f DH	568	pr_notice("FC: ut=%lx ix=%d ni=%u\n",
3bf0fb6f DH	569	fc->untried, fc->index, fc->nr_iterations);
744bcd71 DH	570
	571	if (fc->server_list) {
	572	const struct afs_server_list *sl = fc->server_list;
3bf0fb6f DH	573	pr_notice("FC: SL nr=%u pr=%u vnov=%hx\n",
3bf0fb6f DH	574	sl->nr_servers, sl->preferred, sl->vnovol_mask);
744bcd71 DH	575	for (i = 0; i < sl->nr_servers; i++) {
	576	const struct afs_server *s = sl->servers[i].server;
	577	pr_notice("FC: server fl=%lx av=%u %pU\n",
	578	s->flags, s->addr_version, &s->uuid);
	579	if (s->addresses) {
	580	const struct afs_addr_list *a =
	581	rcu_dereference(s->addresses);
3bf0fb6f	582	pr_notice("FC: - av=%u nr=%u/%u/%u pr=%u\n",
744bcd71 DH	583	a->version,
744bcd71 DH	584	a->nr_ipv4, a->nr_addrs, a->max_addrs,
3bf0fb6f DH	585	a->preferred);
	586	pr_notice("FC: - pr=%lx R=%lx F=%lx\n",
	587	a->probed, a->responded, a->failed);
744bcd71 DH	588	if (a == fc->ac.alist)
	589	pr_notice("FC: - current\n");
	590	}
	591	}
	592	}
	593
3bf0fb6f DH	594	pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
	595	fc->ac.tried, fc->ac.index, fc->ac.abort_code, fc->ac.error,
	596	fc->ac.responded, fc->ac.nr_iterations);
744bcd71 DH	597	rcu_read_unlock();
	598	}
	599
d2ddc776 DH	600	/*
	601	* Tidy up a filesystem cursor and unlock the vnode.
	602	*/
	603	int afs_end_vnode_operation(struct afs_fs_cursor *fc)
	604	{
	605	struct afs_net *net = afs_v2net(fc->vnode);
d2ddc776	606
744bcd71	607	if (fc->error == -EDESTADDRREQ \|\|
4584ae96	608	fc->error == -EADDRNOTAVAIL \|\|
744bcd71 DH	609	fc->error == -ENETUNREACH \|\|
	610	fc->error == -EHOSTUNREACH)
	611	afs_dump_edestaddrreq(fc);
	612
d2ddc776 DH	613	mutex_unlock(&fc->vnode->io_lock);
	614
	615	afs_end_cursor(&fc->ac);
	616	afs_put_cb_interest(net, fc->cbi);
	617	afs_put_serverlist(net, fc->server_list);
	618
e7f680f4 DH	619	if (fc->error == -ECONNABORTED)
e7f680f4 DH	620	fc->error = afs_abort_to_error(fc->ac.abort_code);
d2ddc776	621
e7f680f4	622	return fc->error;
d2ddc776	623	}