WSL2-Linux-Kernel/fs/afs/server.c

503 строки
12 KiB
C

/* server.c: AFS server record management
*
* Copyright (C) 2002 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 License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include <rxrpc/peer.h>
#include <rxrpc/connection.h>
#include "volume.h"
#include "cell.h"
#include "server.h"
#include "transport.h"
#include "vlclient.h"
#include "kafstimod.h"
#include "internal.h"
DEFINE_SPINLOCK(afs_server_peer_lock);
#define FS_SERVICE_ID 1 /* AFS Volume Location Service ID */
#define VL_SERVICE_ID 52 /* AFS Volume Location Service ID */
static void __afs_server_timeout(struct afs_timer *timer)
{
struct afs_server *server =
list_entry(timer, struct afs_server, timeout);
_debug("SERVER TIMEOUT [%p{u=%d}]",
server, atomic_read(&server->usage));
afs_server_do_timeout(server);
}
static const struct afs_timer_ops afs_server_timer_ops = {
.timed_out = __afs_server_timeout,
};
/*****************************************************************************/
/*
* lookup a server record in a cell
* - TODO: search the cell's server list
*/
int afs_server_lookup(struct afs_cell *cell, const struct in_addr *addr,
struct afs_server **_server)
{
struct afs_server *server, *active, *zombie;
int loop;
_enter("%p,%08x,", cell, ntohl(addr->s_addr));
/* allocate and initialise a server record */
server = kmalloc(sizeof(struct afs_server), GFP_KERNEL);
if (!server) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
memset(server, 0, sizeof(struct afs_server));
atomic_set(&server->usage, 1);
INIT_LIST_HEAD(&server->link);
init_rwsem(&server->sem);
INIT_LIST_HEAD(&server->fs_callq);
spin_lock_init(&server->fs_lock);
INIT_LIST_HEAD(&server->cb_promises);
spin_lock_init(&server->cb_lock);
for (loop = 0; loop < AFS_SERVER_CONN_LIST_SIZE; loop++)
server->fs_conn_cnt[loop] = 4;
memcpy(&server->addr, addr, sizeof(struct in_addr));
server->addr.s_addr = addr->s_addr;
afs_timer_init(&server->timeout, &afs_server_timer_ops);
/* add to the cell */
write_lock(&cell->sv_lock);
/* check the active list */
list_for_each_entry(active, &cell->sv_list, link) {
if (active->addr.s_addr == addr->s_addr)
goto use_active_server;
}
/* check the inactive list */
spin_lock(&cell->sv_gylock);
list_for_each_entry(zombie, &cell->sv_graveyard, link) {
if (zombie->addr.s_addr == addr->s_addr)
goto resurrect_server;
}
spin_unlock(&cell->sv_gylock);
afs_get_cell(cell);
server->cell = cell;
list_add_tail(&server->link, &cell->sv_list);
write_unlock(&cell->sv_lock);
*_server = server;
_leave(" = 0 (%p)", server);
return 0;
/* found a matching active server */
use_active_server:
_debug("active server");
afs_get_server(active);
write_unlock(&cell->sv_lock);
kfree(server);
*_server = active;
_leave(" = 0 (%p)", active);
return 0;
/* found a matching server in the graveyard, so resurrect it and
* dispose of the new record */
resurrect_server:
_debug("resurrecting server");
list_del(&zombie->link);
list_add_tail(&zombie->link, &cell->sv_list);
afs_get_server(zombie);
afs_kafstimod_del_timer(&zombie->timeout);
spin_unlock(&cell->sv_gylock);
write_unlock(&cell->sv_lock);
kfree(server);
*_server = zombie;
_leave(" = 0 (%p)", zombie);
return 0;
} /* end afs_server_lookup() */
/*****************************************************************************/
/*
* destroy a server record
* - removes from the cell list
*/
void afs_put_server(struct afs_server *server)
{
struct afs_cell *cell;
if (!server)
return;
_enter("%p", server);
cell = server->cell;
/* sanity check */
BUG_ON(atomic_read(&server->usage) <= 0);
/* to prevent a race, the decrement and the dequeue must be effectively
* atomic */
write_lock(&cell->sv_lock);
if (likely(!atomic_dec_and_test(&server->usage))) {
write_unlock(&cell->sv_lock);
_leave("");
return;
}
spin_lock(&cell->sv_gylock);
list_del(&server->link);
list_add_tail(&server->link, &cell->sv_graveyard);
/* time out in 10 secs */
afs_kafstimod_add_timer(&server->timeout, 10 * HZ);
spin_unlock(&cell->sv_gylock);
write_unlock(&cell->sv_lock);
_leave(" [killed]");
} /* end afs_put_server() */
/*****************************************************************************/
/*
* timeout server record
* - removes from the cell's graveyard if the usage count is zero
*/
void afs_server_do_timeout(struct afs_server *server)
{
struct rxrpc_peer *peer;
struct afs_cell *cell;
int loop;
_enter("%p", server);
cell = server->cell;
BUG_ON(atomic_read(&server->usage) < 0);
/* remove from graveyard if still dead */
spin_lock(&cell->vl_gylock);
if (atomic_read(&server->usage) == 0)
list_del_init(&server->link);
else
server = NULL;
spin_unlock(&cell->vl_gylock);
if (!server) {
_leave("");
return; /* resurrected */
}
/* we can now destroy it properly */
afs_put_cell(cell);
/* uncross-point the structs under a global lock */
spin_lock(&afs_server_peer_lock);
peer = server->peer;
if (peer) {
server->peer = NULL;
peer->user = NULL;
}
spin_unlock(&afs_server_peer_lock);
/* finish cleaning up the server */
for (loop = AFS_SERVER_CONN_LIST_SIZE - 1; loop >= 0; loop--)
if (server->fs_conn[loop])
rxrpc_put_connection(server->fs_conn[loop]);
if (server->vlserver)
rxrpc_put_connection(server->vlserver);
kfree(server);
_leave(" [destroyed]");
} /* end afs_server_do_timeout() */
/*****************************************************************************/
/*
* get a callslot on a connection to the fileserver on the specified server
*/
int afs_server_request_callslot(struct afs_server *server,
struct afs_server_callslot *callslot)
{
struct afs_server_callslot *pcallslot;
struct rxrpc_connection *conn;
int nconn, ret;
_enter("%p,",server);
INIT_LIST_HEAD(&callslot->link);
callslot->task = current;
callslot->conn = NULL;
callslot->nconn = -1;
callslot->ready = 0;
ret = 0;
conn = NULL;
/* get hold of a callslot first */
spin_lock(&server->fs_lock);
/* resurrect the server if it's death timeout has expired */
if (server->fs_state) {
if (time_before(jiffies, server->fs_dead_jif)) {
ret = server->fs_state;
spin_unlock(&server->fs_lock);
_leave(" = %d [still dead]", ret);
return ret;
}
server->fs_state = 0;
}
/* try and find a connection that has spare callslots */
for (nconn = 0; nconn < AFS_SERVER_CONN_LIST_SIZE; nconn++) {
if (server->fs_conn_cnt[nconn] > 0) {
server->fs_conn_cnt[nconn]--;
spin_unlock(&server->fs_lock);
callslot->nconn = nconn;
goto obtained_slot;
}
}
/* none were available - wait interruptibly for one to become
* available */
set_current_state(TASK_INTERRUPTIBLE);
list_add_tail(&callslot->link, &server->fs_callq);
spin_unlock(&server->fs_lock);
while (!callslot->ready && !signal_pending(current)) {
schedule();
set_current_state(TASK_INTERRUPTIBLE);
}
set_current_state(TASK_RUNNING);
/* even if we were interrupted we may still be queued */
if (!callslot->ready) {
spin_lock(&server->fs_lock);
list_del_init(&callslot->link);
spin_unlock(&server->fs_lock);
}
nconn = callslot->nconn;
/* if interrupted, we must release any slot we also got before
* returning an error */
if (signal_pending(current)) {
ret = -EINTR;
goto error_release;
}
/* if we were woken up with an error, then pass that error back to the
* called */
if (nconn < 0) {
_leave(" = %d", callslot->errno);
return callslot->errno;
}
/* were we given a connection directly? */
if (callslot->conn) {
/* yes - use it */
_leave(" = 0 (nc=%d)", nconn);
return 0;
}
/* got a callslot, but no connection */
obtained_slot:
/* need to get hold of the RxRPC connection */
down_write(&server->sem);
/* quick check to see if there's an outstanding error */
ret = server->fs_state;
if (ret)
goto error_release_upw;
if (server->fs_conn[nconn]) {
/* reuse an existing connection */
rxrpc_get_connection(server->fs_conn[nconn]);
callslot->conn = server->fs_conn[nconn];
}
else {
/* create a new connection */
ret = rxrpc_create_connection(afs_transport,
htons(7000),
server->addr.s_addr,
FS_SERVICE_ID,
NULL,
&server->fs_conn[nconn]);
if (ret < 0)
goto error_release_upw;
callslot->conn = server->fs_conn[0];
rxrpc_get_connection(callslot->conn);
}
up_write(&server->sem);
_leave(" = 0");
return 0;
/* handle an error occurring */
error_release_upw:
up_write(&server->sem);
error_release:
/* either release the callslot or pass it along to another deserving
* task */
spin_lock(&server->fs_lock);
if (nconn < 0) {
/* no callslot allocated */
}
else if (list_empty(&server->fs_callq)) {
/* no one waiting */
server->fs_conn_cnt[nconn]++;
spin_unlock(&server->fs_lock);
}
else {
/* someone's waiting - dequeue them and wake them up */
pcallslot = list_entry(server->fs_callq.next,
struct afs_server_callslot, link);
list_del_init(&pcallslot->link);
pcallslot->errno = server->fs_state;
if (!pcallslot->errno) {
/* pass them out callslot details */
callslot->conn = xchg(&pcallslot->conn,
callslot->conn);
pcallslot->nconn = nconn;
callslot->nconn = nconn = -1;
}
pcallslot->ready = 1;
wake_up_process(pcallslot->task);
spin_unlock(&server->fs_lock);
}
rxrpc_put_connection(callslot->conn);
callslot->conn = NULL;
_leave(" = %d", ret);
return ret;
} /* end afs_server_request_callslot() */
/*****************************************************************************/
/*
* release a callslot back to the server
* - transfers the RxRPC connection to the next pending callslot if possible
*/
void afs_server_release_callslot(struct afs_server *server,
struct afs_server_callslot *callslot)
{
struct afs_server_callslot *pcallslot;
_enter("{ad=%08x,cnt=%u},{%d}",
ntohl(server->addr.s_addr),
server->fs_conn_cnt[callslot->nconn],
callslot->nconn);
BUG_ON(callslot->nconn < 0);
spin_lock(&server->fs_lock);
if (list_empty(&server->fs_callq)) {
/* no one waiting */
server->fs_conn_cnt[callslot->nconn]++;
spin_unlock(&server->fs_lock);
}
else {
/* someone's waiting - dequeue them and wake them up */
pcallslot = list_entry(server->fs_callq.next,
struct afs_server_callslot, link);
list_del_init(&pcallslot->link);
pcallslot->errno = server->fs_state;
if (!pcallslot->errno) {
/* pass them out callslot details */
callslot->conn = xchg(&pcallslot->conn, callslot->conn);
pcallslot->nconn = callslot->nconn;
callslot->nconn = -1;
}
pcallslot->ready = 1;
wake_up_process(pcallslot->task);
spin_unlock(&server->fs_lock);
}
rxrpc_put_connection(callslot->conn);
_leave("");
} /* end afs_server_release_callslot() */
/*****************************************************************************/
/*
* get a handle to a connection to the vlserver (volume location) on the
* specified server
*/
int afs_server_get_vlconn(struct afs_server *server,
struct rxrpc_connection **_conn)
{
struct rxrpc_connection *conn;
int ret;
_enter("%p,", server);
ret = 0;
conn = NULL;
down_read(&server->sem);
if (server->vlserver) {
/* reuse an existing connection */
rxrpc_get_connection(server->vlserver);
conn = server->vlserver;
up_read(&server->sem);
}
else {
/* create a new connection */
up_read(&server->sem);
down_write(&server->sem);
if (!server->vlserver) {
ret = rxrpc_create_connection(afs_transport,
htons(7003),
server->addr.s_addr,
VL_SERVICE_ID,
NULL,
&server->vlserver);
}
if (ret == 0) {
rxrpc_get_connection(server->vlserver);
conn = server->vlserver;
}
up_write(&server->sem);
}
*_conn = conn;
_leave(" = %d", ret);
return ret;
} /* end afs_server_get_vlconn() */