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/* 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/slab.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->net, 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 CONFIG_AFS_FSCACHE
volume->cache = fscache_acquire_cookie(volume->cell->cache,
&afs_volume_cache_index_def,
volume, true);
#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(params->net, vlocation);
_leave(" = %p", volume);
return volume;
/* clean up */
error_up:
up_write(¶ms->cell->vl_sem);
error:
afs_put_vlocation(params->net, 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_cb_interest(params->net, volume->cb_interests[loop]);
afs_put_server(params->net, volume->servers[loop]);
}
kfree(volume);
goto error;
}
/*
* destroy a volume record
*/
void afs_put_volume(struct afs_cell *cell, 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(&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(&cell->vl_sem);
/* finish cleaning up the volume */
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(volume->cache, 0);
#endif
afs_put_vlocation(cell->net, vlocation);
for (loop = volume->nservers - 1; loop >= 0; loop--) {
afs_put_cb_interest(cell->net, volume->cb_interests[loop]);
afs_put_server(cell->net, volume->servers[loop]);
}
kfree(volume);
_leave(" [destroyed]");
}
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