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DEFINITIONS
This source file includes following definitions.
- afs_volume_lookup
- afs_put_volume
- afs_volume_pick_fileserver
- afs_volume_release_fileserver
/* AFS volume management
*
* Copyright (C) 2002, 2007 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/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/sched.h>
#include "internal.h"
static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
/*
* lookup a volume by name
* - this can be one of the following:
* "%[cell:]volume[.]" R/W volume
* "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
* or R/W (rwparent=1) volume
* "%[cell:]volume.readonly" R/O volume
* "#[cell:]volume.readonly" R/O volume
* "%[cell:]volume.backup" Backup volume
* "#[cell:]volume.backup" Backup volume
*
* The cell name is optional, and defaults to the current cell.
*
* See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
* Guide
* - Rule 1: Explicit type suffix forces access of that type or nothing
* (no suffix, then use Rule 2 & 3)
* - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
* if not available
* - Rule 3: If parent volume is R/W, then only mount R/W volume unless
* explicitly told otherwise
*/
struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
{
struct afs_vlocation *vlocation = NULL;
struct afs_volume *volume = NULL;
struct afs_server *server = NULL;
char srvtmask;
int ret, loop;
_enter("{%*.*s,%d}",
params->volnamesz, params->volnamesz, params->volname, params->rwpath);
/* lookup the volume location record */
vlocation = afs_vlocation_lookup(params->cell, params->key,
params->volname, params->volnamesz);
if (IS_ERR(vlocation)) {
ret = PTR_ERR(vlocation);
vlocation = NULL;
goto error;
}
/* make the final decision on the type we want */
ret = -ENOMEDIUM;
if (params->force && !(vlocation->vldb.vidmask & (1 << params->type)))
goto error;
srvtmask = 0;
for (loop = 0; loop < vlocation->vldb.nservers; loop++)
srvtmask |= vlocation->vldb.srvtmask[loop];
if (params->force) {
if (!(srvtmask & (1 << params->type)))
goto error;
} else if (srvtmask & AFS_VOL_VTM_RO) {
params->type = AFSVL_ROVOL;
} else if (srvtmask & AFS_VOL_VTM_RW) {
params->type = AFSVL_RWVOL;
} else {
goto error;
}
down_write(¶ms->cell->vl_sem);
/* is the volume already active? */
if (vlocation->vols[params->type]) {
/* yes - re-use it */
volume = vlocation->vols[params->type];
afs_get_volume(volume);
goto success;
}
/* create a new volume record */
_debug("creating new volume record");
ret = -ENOMEM;
volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
if (!volume)
goto error_up;
atomic_set(&volume->usage, 1);
volume->type = params->type;
volume->type_force = params->force;
volume->cell = params->cell;
volume->vid = vlocation->vldb.vid[params->type];
init_rwsem(&volume->server_sem);
/* look up all the applicable server records */
for (loop = 0; loop < 8; loop++) {
if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
server = afs_lookup_server(
volume->cell, &vlocation->vldb.servers[loop]);
if (IS_ERR(server)) {
ret = PTR_ERR(server);
goto error_discard;
}
volume->servers[volume->nservers] = server;
volume->nservers++;
}
}
/* attach the cache and volume location */
#ifdef AFS_CACHING_SUPPORT
cachefs_acquire_cookie(vlocation->cache,
&afs_vnode_cache_index_def,
volume,
&volume->cache);
#endif
afs_get_vlocation(vlocation);
volume->vlocation = vlocation;
vlocation->vols[volume->type] = volume;
success:
_debug("kAFS selected %s volume %08x",
afs_voltypes[volume->type], volume->vid);
up_write(¶ms->cell->vl_sem);
afs_put_vlocation(vlocation);
_leave(" = %p", volume);
return volume;
/* clean up */
error_up:
up_write(¶ms->cell->vl_sem);
error:
afs_put_vlocation(vlocation);
_leave(" = %d", ret);
return ERR_PTR(ret);
error_discard:
up_write(¶ms->cell->vl_sem);
for (loop = volume->nservers - 1; loop >= 0; loop--)
afs_put_server(volume->servers[loop]);
kfree(volume);
goto error;
}
/*
* destroy a volume record
*/
void afs_put_volume(struct afs_volume *volume)
{
struct afs_vlocation *vlocation;
int loop;
if (!volume)
return;
_enter("%p", volume);
ASSERTCMP(atomic_read(&volume->usage), >, 0);
vlocation = volume->vlocation;
/* to prevent a race, the decrement and the dequeue must be effectively
* atomic */
down_write(&vlocation->cell->vl_sem);
if (likely(!atomic_dec_and_test(&volume->usage))) {
up_write(&vlocation->cell->vl_sem);
_leave("");
return;
}
vlocation->vols[volume->type] = NULL;
up_write(&vlocation->cell->vl_sem);
/* finish cleaning up the volume */
#ifdef AFS_CACHING_SUPPORT
cachefs_relinquish_cookie(volume->cache, 0);
#endif
afs_put_vlocation(vlocation);
for (loop = volume->nservers - 1; loop >= 0; loop--)
afs_put_server(volume->servers[loop]);
kfree(volume);
_leave(" [destroyed]");
}
/*
* pick a server to use to try accessing this volume
* - returns with an elevated usage count on the server chosen
*/
struct afs_server *afs_volume_pick_fileserver(struct afs_vnode *vnode)
{
struct afs_volume *volume = vnode->volume;
struct afs_server *server;
int ret, state, loop;
_enter("%s", volume->vlocation->vldb.name);
/* stick with the server we're already using if we can */
if (vnode->server && vnode->server->fs_state == 0) {
afs_get_server(vnode->server);
_leave(" = %p [current]", vnode->server);
return vnode->server;
}
down_read(&volume->server_sem);
/* handle the no-server case */
if (volume->nservers == 0) {
ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
up_read(&volume->server_sem);
_leave(" = %d [no servers]", ret);
return ERR_PTR(ret);
}
/* basically, just search the list for the first live server and use
* that */
ret = 0;
for (loop = 0; loop < volume->nservers; loop++) {
server = volume->servers[loop];
state = server->fs_state;
_debug("consider %d [%d]", loop, state);
switch (state) {
/* found an apparently healthy server */
case 0:
afs_get_server(server);
up_read(&volume->server_sem);
_leave(" = %p (picked %08x)",
server, ntohl(server->addr.s_addr));
return server;
case -ENETUNREACH:
if (ret == 0)
ret = state;
break;
case -EHOSTUNREACH:
if (ret == 0 ||
ret == -ENETUNREACH)
ret = state;
break;
case -ECONNREFUSED:
if (ret == 0 ||
ret == -ENETUNREACH ||
ret == -EHOSTUNREACH)
ret = state;
break;
default:
case -EREMOTEIO:
if (ret == 0 ||
ret == -ENETUNREACH ||
ret == -EHOSTUNREACH ||
ret == -ECONNREFUSED)
ret = state;
break;
}
}
/* no available servers
* - TODO: handle the no active servers case better
*/
up_read(&volume->server_sem);
_leave(" = %d", ret);
return ERR_PTR(ret);
}
/*
* release a server after use
* - releases the ref on the server struct that was acquired by picking
* - records result of using a particular server to access a volume
* - return 0 to try again, 1 if okay or to issue error
* - the caller must release the server struct if result was 0
*/
int afs_volume_release_fileserver(struct afs_vnode *vnode,
struct afs_server *server,
int result)
{
struct afs_volume *volume = vnode->volume;
unsigned loop;
_enter("%s,%08x,%d",
volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
result);
switch (result) {
/* success */
case 0:
server->fs_act_jif = jiffies;
server->fs_state = 0;
_leave("");
return 1;
/* the fileserver denied all knowledge of the volume */
case -ENOMEDIUM:
server->fs_act_jif = jiffies;
down_write(&volume->server_sem);
/* firstly, find where the server is in the active list (if it
* is) */
for (loop = 0; loop < volume->nservers; loop++)
if (volume->servers[loop] == server)
goto present;
/* no longer there - may have been discarded by another op */
goto try_next_server_upw;
present:
volume->nservers--;
memmove(&volume->servers[loop],
&volume->servers[loop + 1],
sizeof(volume->servers[loop]) *
(volume->nservers - loop));
volume->servers[volume->nservers] = NULL;
afs_put_server(server);
volume->rjservers++;
if (volume->nservers > 0)
/* another server might acknowledge its existence */
goto try_next_server_upw;
/* handle the case where all the fileservers have rejected the
* volume
* - TODO: try asking the fileservers for volume information
* - TODO: contact the VL server again to see if the volume is
* no longer registered
*/
up_write(&volume->server_sem);
afs_put_server(server);
_leave(" [completely rejected]");
return 1;
/* problem reaching the server */
case -ENETUNREACH:
case -EHOSTUNREACH:
case -ECONNREFUSED:
case -ETIME:
case -ETIMEDOUT:
case -EREMOTEIO:
/* mark the server as dead
* TODO: vary dead timeout depending on error
*/
spin_lock(&server->fs_lock);
if (!server->fs_state) {
server->fs_dead_jif = jiffies + HZ * 10;
server->fs_state = result;
printk("kAFS: SERVER DEAD state=%d\n", result);
}
spin_unlock(&server->fs_lock);
goto try_next_server;
/* miscellaneous error */
default:
server->fs_act_jif = jiffies;
case -ENOMEM:
case -ENONET:
/* tell the caller to accept the result */
afs_put_server(server);
_leave(" [local failure]");
return 1;
}
/* tell the caller to loop around and try the next server */
try_next_server_upw:
up_write(&volume->server_sem);
try_next_server:
afs_put_server(server);
_leave(" [try next server]");
return 0;
}