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linux/fs/afs/cmservice.c
David Howells f6cbb368bc afs: Actively poll fileservers to maintain NAT or firewall openings 
When an AFS client accesses a file, it receives a limited-duration callback
promise that the server will notify it if another client changes a file.
This callback duration can be a few hours in length.

If a client mounts a volume and then an application prevents it from being
unmounted, say by chdir'ing into it, but then does nothing for some time,
the rxrpc_peer record will expire and rxrpc-level keepalive will cease.

If there is NAT or a firewall between the client and the server, the route
back for the server may close after a comparatively short duration, meaning
that attempts by the server to notify the client may then bounce.

The client, however, may (so far as it knows) still have a valid unexpired
promise and will then rely on its cached data and will not see changes made
on the server by a third party until it incidentally rechecks the status or
the promise needs renewal.

To deal with this, the client needs to regularly probe the server.  This
has two effects: firstly, it keeps a route open back for the server, and
secondly, it causes the server to disgorge any notifications that got
queued up because they couldn't be sent.

Fix this by adding a mechanism to emit regular probes.

Two levels of probing are made available: Under normal circumstances the
'slow' queue will be used for a fileserver - this just probes the preferred
address once every 5 mins or so; however, if server fails to respond to any
probes, the server will shift to the 'fast' queue from which all its
interfaces will be probed every 30s.  When it finally responds, the record
will switch back to the slow queue.

Further notes:

 (1) Probing is now no longer driven from the fileserver rotation
     algorithm.

 (2) Probes are dispatched to all interfaces on a fileserver when that an
     afs_server object is set up to record it.

 (3) The afs_server object is removed from the probe queues when we start
     to probe it.  afs_is_probing_server() returns true if it's not listed
     - ie. it's undergoing probing.

 (4) The afs_server object is added back on to the probe queue when the
     final outstanding probe completes, but the probed_at time is set when
     we're about to launch a probe so that it's not dependent on the probe
     duration.

 (5) The timer and the work item added for this must be handed a count on
     net->servers_outstanding, which they hand on or release.  This makes
     sure that network namespace cleanup waits for them.

Fixes: d2ddc776a4 ("afs: Overhaul volume and server record caching and fileserver rotation")
Reported-by: Dave Botsch <botsch@cnf.cornell.edu>
Signed-off-by: David Howells <dhowells@redhat.com>
2020-05-31 15:19:51 +01:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS Cache Manager Service
*
* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/ip.h>
#include "internal.h"
#include "afs_cm.h"
#include "protocol_yfs.h"
static int afs_deliver_cb_init_call_back_state(struct afs_call *);
static int afs_deliver_cb_init_call_back_state3(struct afs_call *);
static int afs_deliver_cb_probe(struct afs_call *);
static int afs_deliver_cb_callback(struct afs_call *);
static int afs_deliver_cb_probe_uuid(struct afs_call *);
static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *);
static void afs_cm_destructor(struct afs_call *);
static void SRXAFSCB_CallBack(struct work_struct *);
static void SRXAFSCB_InitCallBackState(struct work_struct *);
static void SRXAFSCB_Probe(struct work_struct *);
static void SRXAFSCB_ProbeUuid(struct work_struct *);
static void SRXAFSCB_TellMeAboutYourself(struct work_struct *);
static int afs_deliver_yfs_cb_callback(struct afs_call *);
#define CM_NAME(name) \
char afs_SRXCB##name##_name[] __tracepoint_string = \
"CB." #name
/*
* CB.CallBack operation type
*/
static CM_NAME(CallBack);
static const struct afs_call_type afs_SRXCBCallBack = {
.name = afs_SRXCBCallBack_name,
.deliver = afs_deliver_cb_callback,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_CallBack,
};
/*
* CB.InitCallBackState operation type
*/
static CM_NAME(InitCallBackState);
static const struct afs_call_type afs_SRXCBInitCallBackState = {
.name = afs_SRXCBInitCallBackState_name,
.deliver = afs_deliver_cb_init_call_back_state,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_InitCallBackState,
};
/*
* CB.InitCallBackState3 operation type
*/
static CM_NAME(InitCallBackState3);
static const struct afs_call_type afs_SRXCBInitCallBackState3 = {
.name = afs_SRXCBInitCallBackState3_name,
.deliver = afs_deliver_cb_init_call_back_state3,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_InitCallBackState,
};
/*
* CB.Probe operation type
*/
static CM_NAME(Probe);
static const struct afs_call_type afs_SRXCBProbe = {
.name = afs_SRXCBProbe_name,
.deliver = afs_deliver_cb_probe,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_Probe,
};
/*
* CB.ProbeUuid operation type
*/
static CM_NAME(ProbeUuid);
static const struct afs_call_type afs_SRXCBProbeUuid = {
.name = afs_SRXCBProbeUuid_name,
.deliver = afs_deliver_cb_probe_uuid,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_ProbeUuid,
};
/*
* CB.TellMeAboutYourself operation type
*/
static CM_NAME(TellMeAboutYourself);
static const struct afs_call_type afs_SRXCBTellMeAboutYourself = {
.name = afs_SRXCBTellMeAboutYourself_name,
.deliver = afs_deliver_cb_tell_me_about_yourself,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_TellMeAboutYourself,
};
/*
* YFS CB.CallBack operation type
*/
static CM_NAME(YFS_CallBack);
static const struct afs_call_type afs_SRXYFSCB_CallBack = {
.name = afs_SRXCBYFS_CallBack_name,
.deliver = afs_deliver_yfs_cb_callback,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_CallBack,
};
/*
* route an incoming cache manager call
* - return T if supported, F if not
*/
bool afs_cm_incoming_call(struct afs_call *call)
{
_enter("{%u, CB.OP %u}", call->service_id, call->operation_ID);
call->epoch = rxrpc_kernel_get_epoch(call->net->socket, call->rxcall);
switch (call->operation_ID) {
case CBCallBack:
call->type = &afs_SRXCBCallBack;
return true;
case CBInitCallBackState:
call->type = &afs_SRXCBInitCallBackState;
return true;
case CBInitCallBackState3:
call->type = &afs_SRXCBInitCallBackState3;
return true;
case CBProbe:
call->type = &afs_SRXCBProbe;
return true;
case CBProbeUuid:
call->type = &afs_SRXCBProbeUuid;
return true;
case CBTellMeAboutYourself:
call->type = &afs_SRXCBTellMeAboutYourself;
return true;
case YFSCBCallBack:
if (call->service_id != YFS_CM_SERVICE)
return false;
call->type = &afs_SRXYFSCB_CallBack;
return true;
default:
return false;
}
}
/*
* Record a probe to the cache manager from a server.
*/
static int afs_record_cm_probe(struct afs_call *call, struct afs_server *server)
{
_enter("");
if (test_bit(AFS_SERVER_FL_HAVE_EPOCH, &server->flags) &&
!afs_is_probing_server(server)) {
if (server->cm_epoch == call->epoch)
return 0;
if (!server->probe.said_rebooted) {
pr_notice("kAFS: FS rebooted %pU\n", &server->uuid);
server->probe.said_rebooted = true;
}
}
spin_lock(&server->probe_lock);
if (!test_and_set_bit(AFS_SERVER_FL_HAVE_EPOCH, &server->flags)) {
server->cm_epoch = call->epoch;
server->probe.cm_epoch = call->epoch;
goto out;
}
if (server->probe.cm_probed &&
call->epoch != server->probe.cm_epoch &&
!server->probe.said_inconsistent) {
pr_notice("kAFS: FS endpoints inconsistent %pU\n",
&server->uuid);
server->probe.said_inconsistent = true;
}
if (!server->probe.cm_probed || call->epoch == server->cm_epoch)
server->probe.cm_epoch = server->cm_epoch;
out:
server->probe.cm_probed = true;
spin_unlock(&server->probe_lock);
return 0;
}
/*
* Find the server record by peer address and record a probe to the cache
* manager from a server.
*/
static int afs_find_cm_server_by_peer(struct afs_call *call)
{
struct sockaddr_rxrpc srx;
struct afs_server *server;
rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);
server = afs_find_server(call->net, &srx);
if (!server) {
trace_afs_cm_no_server(call, &srx);
return 0;
}
call->server = server;
return afs_record_cm_probe(call, server);
}
/*
* Find the server record by server UUID and record a probe to the cache
* manager from a server.
*/
static int afs_find_cm_server_by_uuid(struct afs_call *call,
struct afs_uuid *uuid)
{
struct afs_server *server;
rcu_read_lock();
server = afs_find_server_by_uuid(call->net, call->request);
rcu_read_unlock();
if (!server) {
trace_afs_cm_no_server_u(call, call->request);
return 0;
}
call->server = server;
return afs_record_cm_probe(call, server);
}
/*
* Clean up a cache manager call.
*/
static void afs_cm_destructor(struct afs_call *call)
{
kfree(call->buffer);
call->buffer = NULL;
}
/*
* Abort a service call from within an action function.
*/
static void afs_abort_service_call(struct afs_call *call, u32 abort_code, int error,
const char *why)
{
rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
abort_code, error, why);
afs_set_call_complete(call, error, 0);
}
/*
* The server supplied a list of callbacks that it wanted to break.
*/
static void SRXAFSCB_CallBack(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
_enter("");
/* We need to break the callbacks before sending the reply as the
* server holds up change visibility till it receives our reply so as
* to maintain cache coherency.
*/
if (call->server) {
trace_afs_server(call->server,
atomic_read(&call->server->ref),
atomic_read(&call->server->active),
afs_server_trace_callback);
afs_break_callbacks(call->server, call->count, call->request);
}
afs_send_empty_reply(call);
afs_put_call(call);
_leave("");
}
/*
* deliver request data to a CB.CallBack call
*/
static int afs_deliver_cb_callback(struct afs_call *call)
{
struct afs_callback_break *cb;
__be32 *bp;
int ret, loop;
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
afs_extract_to_tmp(call);
call->unmarshall++;
/* extract the FID array and its count in two steps */
/* fall through */
case 1:
_debug("extract FID count");
ret = afs_extract_data(call, true);
if (ret < 0)
return ret;
call->count = ntohl(call->tmp);
_debug("FID count: %u", call->count);
if (call->count > AFSCBMAX)
return afs_protocol_error(call, -EBADMSG,
afs_eproto_cb_fid_count);
call->buffer = kmalloc(array3_size(call->count, 3, 4),
GFP_KERNEL);
if (!call->buffer)
return -ENOMEM;
afs_extract_to_buf(call, call->count * 3 * 4);
call->unmarshall++;
/* Fall through */
case 2:
_debug("extract FID array");
ret = afs_extract_data(call, true);
if (ret < 0)
return ret;
_debug("unmarshall FID array");
call->request = kcalloc(call->count,
sizeof(struct afs_callback_break),
GFP_KERNEL);
if (!call->request)
return -ENOMEM;
cb = call->request;
bp = call->buffer;
for (loop = call->count; loop > 0; loop--, cb++) {
cb->fid.vid = ntohl(*bp++);
cb->fid.vnode = ntohl(*bp++);
cb->fid.unique = ntohl(*bp++);
}
afs_extract_to_tmp(call);
call->unmarshall++;
/* extract the callback array and its count in two steps */
/* fall through */
case 3:
_debug("extract CB count");
ret = afs_extract_data(call, true);
if (ret < 0)
return ret;
call->count2 = ntohl(call->tmp);
_debug("CB count: %u", call->count2);
if (call->count2 != call->count && call->count2 != 0)
return afs_protocol_error(call, -EBADMSG,
afs_eproto_cb_count);
call->iter = &call->def_iter;
iov_iter_discard(&call->def_iter, READ, call->count2 * 3 * 4);
call->unmarshall++;
/* Fall through */
case 4:
_debug("extract discard %zu/%u",
iov_iter_count(call->iter), call->count2 * 3 * 4);
ret = afs_extract_data(call, false);
if (ret < 0)
return ret;
call->unmarshall++;
case 5:
break;
}
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return afs_io_error(call, afs_io_error_cm_reply);
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
return afs_find_cm_server_by_peer(call);
}
/*
* allow the fileserver to request callback state (re-)initialisation
*/
static void SRXAFSCB_InitCallBackState(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
_enter("{%p}", call->server);
if (call->server)
afs_init_callback_state(call->server);
afs_send_empty_reply(call);
afs_put_call(call);
_leave("");
}
/*
* deliver request data to a CB.InitCallBackState call
*/
static int afs_deliver_cb_init_call_back_state(struct afs_call *call)
{
int ret;
_enter("");
afs_extract_discard(call, 0);
ret = afs_extract_data(call, false);
if (ret < 0)
return ret;
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
return afs_find_cm_server_by_peer(call);
}
/*
* deliver request data to a CB.InitCallBackState3 call
*/
static int afs_deliver_cb_init_call_back_state3(struct afs_call *call)
{
struct afs_uuid *r;
unsigned loop;
__be32 *b;
int ret;
_enter("");
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
call->buffer = kmalloc_array(11, sizeof(__be32), GFP_KERNEL);
if (!call->buffer)
return -ENOMEM;
afs_extract_to_buf(call, 11 * sizeof(__be32));
call->unmarshall++;
/* Fall through */
case 1:
_debug("extract UUID");
ret = afs_extract_data(call, false);
switch (ret) {
case 0: break;
case -EAGAIN: return 0;
default: return ret;
}
_debug("unmarshall UUID");
call->request = kmalloc(sizeof(struct afs_uuid), GFP_KERNEL);
if (!call->request)
return -ENOMEM;
b = call->buffer;
r = call->request;
r->time_low = b[0];
r->time_mid = htons(ntohl(b[1]));
r->time_hi_and_version = htons(ntohl(b[2]));
r->clock_seq_hi_and_reserved = ntohl(b[3]);
r->clock_seq_low = ntohl(b[4]);
for (loop = 0; loop < 6; loop++)
r->node[loop] = ntohl(b[loop + 5]);
call->unmarshall++;
case 2:
break;
}
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return afs_io_error(call, afs_io_error_cm_reply);
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
return afs_find_cm_server_by_uuid(call, call->request);
}
/*
* allow the fileserver to see if the cache manager is still alive
*/
static void SRXAFSCB_Probe(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
_enter("");
afs_send_empty_reply(call);
afs_put_call(call);
_leave("");
}
/*
* deliver request data to a CB.Probe call
*/
static int afs_deliver_cb_probe(struct afs_call *call)
{
int ret;
_enter("");
afs_extract_discard(call, 0);
ret = afs_extract_data(call, false);
if (ret < 0)
return ret;
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return afs_io_error(call, afs_io_error_cm_reply);
return afs_find_cm_server_by_peer(call);
}
/*
* allow the fileserver to quickly find out if the fileserver has been rebooted
*/
static void SRXAFSCB_ProbeUuid(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
struct afs_uuid *r = call->request;
_enter("");
if (memcmp(r, &call->net->uuid, sizeof(call->net->uuid)) == 0)
afs_send_empty_reply(call);
else
afs_abort_service_call(call, 1, 1, "K-1");
afs_put_call(call);
_leave("");
}
/*
* deliver request data to a CB.ProbeUuid call
*/
static int afs_deliver_cb_probe_uuid(struct afs_call *call)
{
struct afs_uuid *r;
unsigned loop;
__be32 *b;
int ret;
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
call->buffer = kmalloc_array(11, sizeof(__be32), GFP_KERNEL);
if (!call->buffer)
return -ENOMEM;
afs_extract_to_buf(call, 11 * sizeof(__be32));
call->unmarshall++;
/* Fall through */
case 1:
_debug("extract UUID");
ret = afs_extract_data(call, false);
switch (ret) {
case 0: break;
case -EAGAIN: return 0;
default: return ret;
}
_debug("unmarshall UUID");
call->request = kmalloc(sizeof(struct afs_uuid), GFP_KERNEL);
if (!call->request)
return -ENOMEM;
b = call->buffer;
r = call->request;
r->time_low = b[0];
r->time_mid = htons(ntohl(b[1]));
r->time_hi_and_version = htons(ntohl(b[2]));
r->clock_seq_hi_and_reserved = ntohl(b[3]);
r->clock_seq_low = ntohl(b[4]);
for (loop = 0; loop < 6; loop++)
r->node[loop] = ntohl(b[loop + 5]);
call->unmarshall++;
case 2:
break;
}
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return afs_io_error(call, afs_io_error_cm_reply);
return afs_find_cm_server_by_uuid(call, call->request);
}
/*
* allow the fileserver to ask about the cache manager's capabilities
*/
static void SRXAFSCB_TellMeAboutYourself(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
int loop;
struct {
struct /* InterfaceAddr */ {
__be32 nifs;
__be32 uuid[11];
__be32 ifaddr[32];
__be32 netmask[32];
__be32 mtu[32];
} ia;
struct /* Capabilities */ {
__be32 capcount;
__be32 caps[1];
} cap;
} reply;
_enter("");
memset(&reply, 0, sizeof(reply));
reply.ia.uuid[0] = call->net->uuid.time_low;
reply.ia.uuid[1] = htonl(ntohs(call->net->uuid.time_mid));
reply.ia.uuid[2] = htonl(ntohs(call->net->uuid.time_hi_and_version));
reply.ia.uuid[3] = htonl((s8) call->net->uuid.clock_seq_hi_and_reserved);
reply.ia.uuid[4] = htonl((s8) call->net->uuid.clock_seq_low);
for (loop = 0; loop < 6; loop++)
reply.ia.uuid[loop + 5] = htonl((s8) call->net->uuid.node[loop]);
reply.cap.capcount = htonl(1);
reply.cap.caps[0] = htonl(AFS_CAP_ERROR_TRANSLATION);
afs_send_simple_reply(call, &reply, sizeof(reply));
afs_put_call(call);
_leave("");
}
/*
* deliver request data to a CB.TellMeAboutYourself call
*/
static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call)
{
int ret;
_enter("");
afs_extract_discard(call, 0);
ret = afs_extract_data(call, false);
if (ret < 0)
return ret;
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return afs_io_error(call, afs_io_error_cm_reply);
return afs_find_cm_server_by_peer(call);
}
/*
* deliver request data to a YFS CB.CallBack call
*/
static int afs_deliver_yfs_cb_callback(struct afs_call *call)
{
struct afs_callback_break *cb;
struct yfs_xdr_YFSFid *bp;
size_t size;
int ret, loop;
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
afs_extract_to_tmp(call);
call->unmarshall++;
/* extract the FID array and its count in two steps */
/* Fall through */
case 1:
_debug("extract FID count");
ret = afs_extract_data(call, true);
if (ret < 0)
return ret;
call->count = ntohl(call->tmp);
_debug("FID count: %u", call->count);
if (call->count > YFSCBMAX)
return afs_protocol_error(call, -EBADMSG,
afs_eproto_cb_fid_count);
size = array_size(call->count, sizeof(struct yfs_xdr_YFSFid));
call->buffer = kmalloc(size, GFP_KERNEL);
if (!call->buffer)
return -ENOMEM;
afs_extract_to_buf(call, size);
call->unmarshall++;
/* Fall through */
case 2:
_debug("extract FID array");
ret = afs_extract_data(call, false);
if (ret < 0)
return ret;
_debug("unmarshall FID array");
call->request = kcalloc(call->count,
sizeof(struct afs_callback_break),
GFP_KERNEL);
if (!call->request)
return -ENOMEM;
cb = call->request;
bp = call->buffer;
for (loop = call->count; loop > 0; loop--, cb++) {
cb->fid.vid = xdr_to_u64(bp->volume);
cb->fid.vnode = xdr_to_u64(bp->vnode.lo);
cb->fid.vnode_hi = ntohl(bp->vnode.hi);
cb->fid.unique = ntohl(bp->vnode.unique);
bp++;
}
afs_extract_to_tmp(call);
call->unmarshall++;
case 3:
break;
}
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return afs_io_error(call, afs_io_error_cm_reply);
/* We'll need the file server record as that tells us which set of
* vnodes to operate upon.
*/
return afs_find_cm_server_by_peer(call);
}
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