linux/fs/afs/rotate.c
Gustavo A. R. Silva df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00

514 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* Handle fileserver selection and rotation.
*
* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#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 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_operation *op,
struct afs_vnode *vnode)
{
struct afs_server *server;
void *cb_server;
int i;
read_lock(&op->volume->servers_lock);
op->server_list = afs_get_serverlist(
rcu_dereference_protected(op->volume->servers,
lockdep_is_held(&op->volume->servers_lock)));
read_unlock(&op->volume->servers_lock);
op->untried = (1UL << op->server_list->nr_servers) - 1;
op->index = READ_ONCE(op->server_list->preferred);
cb_server = vnode->cb_server;
if (cb_server) {
/* See if the vnode's preferred record is still available */
for (i = 0; i < op->server_list->nr_servers; i++) {
server = op->server_list->servers[i].server;
if (server == cb_server) {
op->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 (op->flags & AFS_OPERATION_CUR_ONLY) {
op->error = -ESTALE;
return false;
}
/* Note that the callback promise is effectively broken */
write_seqlock(&vnode->cb_lock);
ASSERTCMP(cb_server, ==, vnode->cb_server);
vnode->cb_server = NULL;
if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
vnode->cb_break++;
write_sequnlock(&vnode->cb_lock);
}
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_operation *op)
{
if (!(op->flags & AFS_OPERATION_UNINTR)) {
msleep_interruptible(1000);
if (signal_pending(current)) {
op->error = -ERESTARTSYS;
return false;
}
} else {
msleep(1000);
}
return true;
}
/*
* Select the fileserver to use. May be called multiple times to rotate
* through the fileservers.
*/
bool afs_select_fileserver(struct afs_operation *op)
{
struct afs_addr_list *alist;
struct afs_server *server;
struct afs_vnode *vnode = op->file[0].vnode;
struct afs_error e;
u32 rtt;
int error = op->ac.error, i;
_enter("%lx[%d],%lx[%d],%d,%d",
op->untried, op->index,
op->ac.tried, op->ac.index,
error, op->ac.abort_code);
if (op->flags & AFS_OPERATION_STOP) {
_leave(" = f [stopped]");
return false;
}
op->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. */
op->error = error;
op->flags |= AFS_OPERATION_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 (op->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 (op->flags & AFS_OPERATION_VNOVOL) {
op->error = -EREMOTEIO;
goto next_server;
}
write_lock(&op->volume->servers_lock);
op->server_list->vnovol_mask |= 1 << op->index;
write_unlock(&op->volume->servers_lock);
set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
error = afs_check_volume_status(op->volume, op);
if (error < 0)
goto failed_set_error;
if (test_bit(AFS_VOLUME_DELETED, &op->volume->flags)) {
op->error = -ENOMEDIUM;
goto failed;
}
/* If the server list didn't change, then assume that
* it's the fileserver having trouble.
*/
if (rcu_access_pointer(op->volume->servers) == op->server_list) {
op->error = -EREMOTEIO;
goto next_server;
}
/* Try again */
op->flags |= AFS_OPERATION_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:
op->error = afs_abort_to_error(op->ac.abort_code);
goto next_server;
case VOFFLINE:
if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &op->volume->flags)) {
afs_busy(op->volume, op->ac.abort_code);
clear_bit(AFS_VOLUME_BUSY, &op->volume->flags);
}
if (op->flags & AFS_OPERATION_NO_VSLEEP) {
op->error = -EADV;
goto failed;
}
if (op->flags & AFS_OPERATION_CUR_ONLY) {
op->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 (op->flags & AFS_OPERATION_NO_VSLEEP) {
op->error = -EBUSY;
goto failed;
}
if (!test_and_set_bit(AFS_VOLUME_BUSY, &op->volume->flags)) {
afs_busy(op->volume, op->ac.abort_code);
clear_bit(AFS_VOLUME_OFFLINE, &op->volume->flags);
}
busy:
if (op->flags & AFS_OPERATION_CUR_ONLY) {
if (!afs_sleep_and_retry(op))
goto failed;
/* Retry with same server & address */
_leave(" = t [vbusy]");
return true;
}
op->flags |= AFS_OPERATION_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 (op->flags & AFS_OPERATION_VMOVED) {
op->error = -EREMOTEIO;
goto failed;
}
op->flags |= AFS_OPERATION_VMOVED;
set_bit(AFS_VOLUME_WAIT, &op->volume->flags);
set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
error = afs_check_volume_status(op->volume, op);
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 (rcu_access_pointer(op->volume->servers) == op->server_list) {
op->error = -ENOMEDIUM;
goto failed;
}
goto restart_from_beginning;
default:
clear_bit(AFS_VOLUME_OFFLINE, &op->volume->flags);
clear_bit(AFS_VOLUME_BUSY, &op->volume->flags);
op->error = afs_abort_to_error(op->ac.abort_code);
goto failed;
}
case -ETIMEDOUT:
case -ETIME:
if (op->error != -EDESTADDRREQ)
goto iterate_address;
fallthrough;
case -ERFKILL:
case -EADDRNOTAVAIL:
case -ENETUNREACH:
case -EHOSTUNREACH:
case -EHOSTDOWN:
case -ECONNREFUSED:
_debug("no conn");
op->error = error;
goto iterate_address;
case -ECONNRESET:
_debug("call reset");
op->error = error;
goto failed;
}
restart_from_beginning:
_debug("restart");
afs_end_cursor(&op->ac);
op->server = NULL;
afs_put_serverlist(op->net, op->server_list);
op->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(op->volume, op);
if (error < 0)
goto failed_set_error;
if (!afs_start_fs_iteration(op, vnode))
goto failed;
_debug("__ VOL %llx __", op->volume->vid);
pick_server:
_debug("pick [%lx]", op->untried);
error = afs_wait_for_fs_probes(op->server_list, op->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 (op->server) {
_debug("server %u", op->index);
if (test_bit(op->index, &op->untried))
goto selected_server;
op->server = NULL;
_debug("no server");
}
op->index = -1;
rtt = U32_MAX;
for (i = 0; i < op->server_list->nr_servers; i++) {
struct afs_server *s = op->server_list->servers[i].server;
if (!test_bit(i, &op->untried) ||
!test_bit(AFS_SERVER_FL_RESPONDING, &s->flags))
continue;
if (s->probe.rtt < rtt) {
op->index = i;
rtt = s->probe.rtt;
}
}
if (op->index == -1)
goto no_more_servers;
selected_server:
_debug("use %d", op->index);
__clear_bit(op->index, &op->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(op->ac.alist, ==, NULL);
server = op->server_list->servers[op->index].server;
if (!afs_check_server_record(op, server))
goto failed;
_debug("USING SERVER: %pU", &server->uuid);
op->flags |= AFS_OPERATION_RETRY_SERVER;
op->server = server;
if (vnode->cb_server != server) {
vnode->cb_server = server;
vnode->cb_s_break = server->cb_s_break;
vnode->cb_v_break = vnode->volume->cb_v_break;
clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
}
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);
retry_server:
memset(&op->ac, 0, sizeof(op->ac));
if (!op->ac.alist)
op->ac.alist = alist;
else
afs_put_addrlist(alist);
op->ac.index = -1;
iterate_address:
ASSERT(op->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(&op->ac))
goto out_of_addresses;
_debug("address [%u] %u/%u %pISp",
op->index, op->ac.index, op->ac.alist->nr_addrs,
&op->ac.alist->addrs[op->ac.index].transport);
_leave(" = t");
return true;
out_of_addresses:
/* We've now had a failure to respond on all of a server's addresses -
* immediately probe them again and consider retrying the server.
*/
afs_probe_fileserver(op->net, op->server);
if (op->flags & AFS_OPERATION_RETRY_SERVER) {
alist = op->ac.alist;
error = afs_wait_for_one_fs_probe(
op->server, !(op->flags & AFS_OPERATION_UNINTR));
switch (error) {
case 0:
op->flags &= ~AFS_OPERATION_RETRY_SERVER;
goto retry_server;
case -ERESTARTSYS:
goto failed_set_error;
case -ETIME:
case -EDESTADDRREQ:
goto next_server;
}
}
next_server:
_debug("next");
afs_end_cursor(&op->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 (op->flags & AFS_OPERATION_VBUSY)
goto restart_from_beginning;
e.error = -EDESTADDRREQ;
e.responded = false;
for (i = 0; i < op->server_list->nr_servers; i++) {
struct afs_server *s = op->server_list->servers[i].server;
afs_prioritise_error(&e, READ_ONCE(s->probe.error),
s->probe.abort_code);
}
error = e.error;
failed_set_error:
op->error = error;
failed:
op->flags |= AFS_OPERATION_STOP;
afs_end_cursor(&op->ac);
_leave(" = f [failed %d]", op->error);
return false;
}
/*
* Dump cursor state in the case of the error being EDESTADDRREQ.
*/
void afs_dump_edestaddrreq(const struct afs_operation *op)
{
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=%x err=%hd\n",
op->file[0].cb_break_before,
op->file[1].cb_break_before, op->flags, op->error);
pr_notice("FC: ut=%lx ix=%d ni=%u\n",
op->untried, op->index, op->nr_iterations);
if (op->server_list) {
const struct afs_server_list *sl = op->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: - R=%lx F=%lx\n",
a->responded, a->failed);
if (a == op->ac.alist)
pr_notice("FC: - current\n");
}
}
}
pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
op->ac.tried, op->ac.index, op->ac.abort_code, op->ac.error,
op->ac.responded, op->ac.nr_iterations);
rcu_read_unlock();
}