- 根目录:
- fs
- afs
- vlocation.c
/* AFS volume location 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/slab.h>
#include <linux/init.h>
#include <linux/sched.h>
#include "internal.h"
static unsigned afs_vlocation_timeout = 10; /* volume location timeout in seconds */
static unsigned afs_vlocation_update_timeout = 10 * 60;
static void afs_vlocation_reaper(struct work_struct *);
static void afs_vlocation_updater(struct work_struct *);
static LIST_HEAD(afs_vlocation_updates);
static LIST_HEAD(afs_vlocation_graveyard);
static DEFINE_SPINLOCK(afs_vlocation_updates_lock);
static DEFINE_SPINLOCK(afs_vlocation_graveyard_lock);
static DECLARE_DELAYED_WORK(afs_vlocation_reap, afs_vlocation_reaper);
static DECLARE_DELAYED_WORK(afs_vlocation_update, afs_vlocation_updater);
static struct workqueue_struct *afs_vlocation_update_worker;
/*
* iterate through the VL servers in a cell until one of them admits knowing
* about the volume in question
*/
static int afs_vlocation_access_vl_by_name(struct afs_vlocation *vl,
struct key *key,
struct afs_cache_vlocation *vldb)
{
struct afs_cell *cell = vl->cell;
struct in_addr addr;
int count, ret;
_enter("%s,%s", cell->name, vl->vldb.name);
down_write(&vl->cell->vl_sem);
ret = -ENOMEDIUM;
for (count = cell->vl_naddrs; count > 0; count--) {
addr = cell->vl_addrs[cell->vl_curr_svix];
_debug("CellServ[%hu]: %08x", cell->vl_curr_svix, addr.s_addr);
/* attempt to access the VL server */
ret = afs_vl_get_entry_by_name(&addr, key, vl->vldb.name, vldb,
&afs_sync_call);
switch (ret) {
case 0:
goto out;
case -ENOMEM:
case -ENONET:
case -ENETUNREACH:
case -EHOSTUNREACH:
case -ECONNREFUSED:
if (ret == -ENOMEM || ret == -ENONET)
goto out;
goto rotate;
case -ENOMEDIUM:
case -EKEYREJECTED:
case -EKEYEXPIRED:
goto out;
default:
ret = -EIO;
goto rotate;
}
/* rotate the server records upon lookup failure */
rotate:
cell->vl_curr_svix++;
cell->vl_curr_svix %= cell->vl_naddrs;
}
out:
up_write(&vl->cell->vl_sem);
_leave(" = %d", ret);
return ret;
}
/*
* iterate through the VL servers in a cell until one of them admits knowing
* about the volume in question
*/
static int afs_vlocation_access_vl_by_id(struct afs_vlocation *vl,
struct key *key,
afs_volid_t volid,
afs_voltype_t voltype,
struct afs_cache_vlocation *vldb)
{
struct afs_cell *cell = vl->cell;
struct in_addr addr;
int count, ret;
_enter("%s,%x,%d,", cell->name, volid, voltype);
down_write(&vl->cell->vl_sem);
ret = -ENOMEDIUM;
for (count = cell->vl_naddrs; count > 0; count--) {
addr = cell->vl_addrs[cell->vl_curr_svix];
_debug("CellServ[%hu]: %08x", cell->vl_curr_svix, addr.s_addr);
/* attempt to access the VL server */
ret = afs_vl_get_entry_by_id(&addr, key, volid, voltype, vldb,
&afs_sync_call);
switch (ret) {
case 0:
goto out;
case -ENOMEM:
case -ENONET:
case -ENETUNREACH:
case -EHOSTUNREACH:
case -ECONNREFUSED:
if (ret == -ENOMEM || ret == -ENONET)
goto out;
goto rotate;
case -EBUSY:
vl->upd_busy_cnt++;
if (vl->upd_busy_cnt <= 3) {
if (vl->upd_busy_cnt > 1) {
/* second+ BUSY - sleep a little bit */
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(1);
__set_current_state(TASK_RUNNING);
}
continue;
}
break;
case -ENOMEDIUM:
vl->upd_rej_cnt++;
goto rotate;
default:
ret = -EIO;
goto rotate;
}
/* rotate the server records upon lookup failure */
rotate:
cell->vl_curr_svix++;
cell->vl_curr_svix %= cell->vl_naddrs;
vl->upd_busy_cnt = 0;
}
out:
if (ret < 0 && vl->upd_rej_cnt > 0) {
printk(KERN_NOTICE "kAFS:"
" Active volume no longer valid '%s'\n",
vl->vldb.name);
vl->valid = 0;
ret = -ENOMEDIUM;
}
up_write(&vl->cell->vl_sem);
_leave(" = %d", ret);
return ret;
}
/*
* allocate a volume location record
*/
static struct afs_vlocation *afs_vlocation_alloc(struct afs_cell *cell,
const char *name,
size_t namesz)
{
struct afs_vlocation *vl;
vl = kzalloc(sizeof(struct afs_vlocation), GFP_KERNEL);
if (vl) {
vl->cell = cell;
vl->state = AFS_VL_NEW;
atomic_set(&vl->usage, 1);
INIT_LIST_HEAD(&vl->link);
INIT_LIST_HEAD(&vl->grave);
INIT_LIST_HEAD(&vl->update);
init_waitqueue_head(&vl->waitq);
spin_lock_init(&vl->lock);
memcpy(vl->vldb.name, name, namesz);
}
_leave(" = %p", vl);
return vl;
}
/*
* update record if we found it in the cache
*/
static int afs_vlocation_update_record(struct afs_vlocation *vl,
struct key *key,
struct afs_cache_vlocation *vldb)
{
afs_voltype_t voltype;
afs_volid_t vid;
int ret;
/* try to look up a cached volume in the cell VL databases by ID */
_debug("Locally Cached: %s %02x { %08x(%x) %08x(%x) %08x(%x) }",
vl->vldb.name,
vl->vldb.vidmask,
ntohl(vl->vldb.servers[0].s_addr),
vl->vldb.srvtmask[0],
ntohl(vl->vldb.servers[1].s_addr),
vl->vldb.srvtmask[1],
ntohl(vl->vldb.servers[2].s_addr),
vl->vldb.srvtmask[2]);
_debug("Vids: %08x %08x %08x",
vl->vldb.vid[0],
vl->vldb.vid[1],
vl->vldb.vid[2]);
if (vl->vldb.vidmask & AFS_VOL_VTM_RW) {
vid = vl->vldb.vid[0];
voltype = AFSVL_RWVOL;
} else if (vl->vldb.vidmask & AFS_VOL_VTM_RO) {
vid = vl->vldb.vid[1];
voltype = AFSVL_ROVOL;
} else if (vl->vldb.vidmask & AFS_VOL_VTM_BAK) {
vid = vl->vldb.vid[2];
voltype = AFSVL_BACKVOL;
} else {
BUG();
vid = 0;
voltype = 0;
}
/* contact the server to make sure the volume is still available
* - TODO: need to handle disconnected operation here
*/
ret = afs_vlocation_access_vl_by_id(vl, key, vid, voltype, vldb);
switch (ret) {
/* net error */
default:
printk(KERN_WARNING "kAFS:"
" failed to update volume '%s' (%x) up in '%s': %d\n",
vl->vldb.name, vid, vl->cell->name, ret);
_leave(" = %d", ret);
return ret;
/* pulled from local cache into memory */
case 0:
_leave(" = 0");
return 0;
/* uh oh... looks like the volume got deleted */
case -ENOMEDIUM:
printk(KERN_ERR "kAFS:"
" volume '%s' (%x) does not exist '%s'\n",
vl->vldb.name, vid, vl->cell->name);
/* TODO: make existing record unavailable */
_leave(" = %d", ret);
return ret;
}
}
/*
* apply the update to a VL record
*/
static void afs_vlocation_apply_update(struct afs_vlocation *vl,
struct afs_cache_vlocation *vldb)
{
_debug("Done VL Lookup: %s %02x { %08x(%x) %08x(%x) %08x(%x) }",
vldb->name, vldb->vidmask,
ntohl(vldb->servers[0].s_addr), vldb->srvtmask[0],
ntohl(vldb->servers[1].s_addr), vldb->srvtmask[1],
ntohl(vldb->servers[2].s_addr), vldb->srvtmask[2]);
_debug("Vids: %08x %08x %08x",
vldb->vid[0], vldb->vid[1], vldb->vid[2]);
if (strcmp(vldb->name, vl->vldb.name) != 0)
printk(KERN_NOTICE "kAFS:"
" name of volume '%s' changed to '%s' on server\n",
vl->vldb.name, vldb->name);
vl->vldb = *vldb;
#ifdef CONFIG_AFS_FSCACHE
fscache_update_cookie(vl->cache);
#endif
}
/*
* fill in a volume location record, consulting the cache and the VL server
* both
*/
static int afs_vlocation_fill_in_record(struct afs_vlocation *vl,
struct key *key)
{
struct afs_cache_vlocation vldb;
int ret;
_enter("");
ASSERTCMP(vl->valid, ==, 0);
memset(&vldb, 0, sizeof(vldb));
/* see if we have an in-cache copy (will set vl->valid if there is) */
#ifdef CONFIG_AFS_FSCACHE
vl->cache = fscache_acquire_cookie(vl->cell->cache,
&afs_vlocation_cache_index_def, vl);
#endif
if (vl->valid) {
/* try to update a known volume in the cell VL databases by
* ID as the name may have changed */
_debug("found in cache");
ret = afs_vlocation_update_record(vl, key, &vldb);
} else {
/* try to look up an unknown volume in the cell VL databases by
* name */
ret = afs_vlocation_access_vl_by_name(vl, key, &vldb);
if (ret < 0) {
printk("kAFS: failed to locate '%s' in cell '%s'\n",
vl->vldb.name, vl->cell->name);
return ret;
}
}
afs_vlocation_apply_update(vl, &vldb);
_leave(" = 0");
return 0;
}
/*
* queue a vlocation record for updates
*/
static void afs_vlocation_queue_for_updates(struct afs_vlocation *vl)
{
struct afs_vlocation *xvl;
/* wait at least 10 minutes before updating... */
vl->update_at = get_seconds() + afs_vlocation_update_timeout;
spin_lock(&afs_vlocation_updates_lock);
if (!list_empty(&afs_vlocation_updates)) {
/* ... but wait at least 1 second more than the newest record
* already queued so that we don't spam the VL server suddenly
* with lots of requests
*/
xvl = list_entry(afs_vlocation_updates.prev,
struct afs_vlocation, update);
if (vl->update_at <= xvl->update_at)
vl->update_at = xvl->update_at + 1;
} else {
queue_delayed_work(afs_vlocation_update_worker,
&afs_vlocation_update,
afs_vlocation_update_timeout * HZ);
}
list_add_tail(&vl->update, &afs_vlocation_updates);
spin_unlock(&afs_vlocation_updates_lock);
}
/*
* lookup volume location
* - iterate through the VL servers in a cell until one of them admits knowing
* about the volume in question
* - lookup in the local cache if not able to find on the VL server
* - insert/update in the local cache if did get a VL response
*/
struct afs_vlocation *afs_vlocation_lookup(struct afs_cell *cell,
struct key *key,
const char *name,
size_t namesz)
{
struct afs_vlocation *vl;
int ret;
_enter("{%s},{%x},%*.*s,%zu",
cell->name, key_serial(key),
(int) namesz, (int) namesz, name, namesz);
if (namesz >= sizeof(vl->vldb.name)) {
_leave(" = -ENAMETOOLONG");
return ERR_PTR(-ENAMETOOLONG);
}
/* see if we have an in-memory copy first */
down_write(&cell->vl_sem);
spin_lock(&cell->vl_lock);
list_for_each_entry(vl, &cell->vl_list, link) {
if (vl->vldb.name[namesz] != '\0')
continue;
if (memcmp(vl->vldb.name, name, namesz) == 0)
goto found_in_memory;
}
spin_unlock(&cell->vl_lock);
/* not in the cell's in-memory lists - create a new record */
vl = afs_vlocation_alloc(cell, name, namesz);
if (!vl) {
up_write(&cell->vl_sem);
return ERR_PTR(-ENOMEM);
}
afs_get_cell(cell);
list_add_tail(&vl->link, &cell->vl_list);
vl->state = AFS_VL_CREATING;
up_write(&cell->vl_sem);
fill_in_record:
ret = afs_vlocation_fill_in_record(vl, key);
if (ret < 0)
goto error_abandon;
spin_lock(&vl->lock);
vl->state = AFS_VL_VALID;
spin_unlock(&vl->lock);
wake_up(&vl->waitq);
/* update volume entry in local cache */
#ifdef CONFIG_AFS_FSCACHE
fscache_update_cookie(vl->cache);
#endif
/* schedule for regular updates */
afs_vlocation_queue_for_updates(vl);
goto success;
found_in_memory:
/* found in memory */
_debug("found in memory");
atomic_inc(&vl->usage);
spin_unlock(&cell->vl_lock);
if (!list_empty(&vl->grave)) {
spin_lock(&afs_vlocation_graveyard_lock);
list_del_init(&vl->grave);
spin_unlock(&afs_vlocation_graveyard_lock);
}
up_write(&cell->vl_sem);
/* see if it was an abandoned record that we might try filling in */
spin_lock(&vl->lock);
while (vl->state != AFS_VL_VALID) {
afs_vlocation_state_t state = vl->state;
_debug("invalid [state %d]", state);
if (state == AFS_VL_NEW || state == AFS_VL_NO_VOLUME) {
vl->state = AFS_VL_CREATING;
spin_unlock(&vl->lock);
goto fill_in_record;
}
/* must now wait for creation or update by someone else to
* complete */
_debug("wait");
spin_unlock(&vl->lock);
ret = wait_event_interruptible(vl->waitq,
vl->state == AFS_VL_NEW ||
vl->state == AFS_VL_VALID ||
vl->state == AFS_VL_NO_VOLUME);
if (ret < 0)
goto error;
spin_lock(&vl->lock);
}
spin_unlock(&vl->lock);
success:
_leave(" = %p", vl);
return vl;
error_abandon:
spin_lock(&vl->lock);
vl->state = AFS_VL_NEW;
spin_unlock(&vl->lock);
wake_up(&vl->waitq);
error:
ASSERT(vl != NULL);
afs_put_vlocation(vl);
_leave(" = %d", ret);
return ERR_PTR(ret);
}
/*
* finish using a volume location record
*/
void afs_put_vlocation(struct afs_vlocation *vl)
{
if (!vl)
return;
_enter("%s", vl->vldb.name);
ASSERTCMP(atomic_read(&vl->usage), >, 0);
if (likely(!atomic_dec_and_test(&vl->usage))) {
_leave("");
return;
}
spin_lock(&afs_vlocation_graveyard_lock);
if (atomic_read(&vl->usage) == 0) {
_debug("buried");
list_move_tail(&vl->grave, &afs_vlocation_graveyard);
vl->time_of_death = get_seconds();
queue_delayed_work(afs_wq, &afs_vlocation_reap,
afs_vlocation_timeout * HZ);
/* suspend updates on this record */
if (!list_empty(&vl->update)) {
spin_lock(&afs_vlocation_updates_lock);
list_del_init(&vl->update);
spin_unlock(&afs_vlocation_updates_lock);
}
}
spin_unlock(&afs_vlocation_graveyard_lock);
_leave(" [killed?]");
}
/*
* destroy a dead volume location record
*/
static void afs_vlocation_destroy(struct afs_vlocation *vl)
{
_enter("%p", vl);
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(vl->cache, 0);
#endif
afs_put_cell(vl->cell);
kfree(vl);
}
/*
* reap dead volume location records
*/
static void afs_vlocation_reaper(struct work_struct *work)
{
LIST_HEAD(corpses);
struct afs_vlocation *vl;
unsigned long delay, expiry;
time_t now;
_enter("");
now = get_seconds();
spin_lock(&afs_vlocation_graveyard_lock);
while (!list_empty(&afs_vlocation_graveyard)) {
vl = list_entry(afs_vlocation_graveyard.next,
struct afs_vlocation, grave);
_debug("check %p", vl);
/* the queue is ordered most dead first */
expiry = vl->time_of_death + afs_vlocation_timeout;
if (expiry > now) {
delay = (expiry - now) * HZ;
_debug("delay %lu", delay);
if (!queue_delayed_work(afs_wq, &afs_vlocation_reap,
delay)) {
cancel_delayed_work(&afs_vlocation_reap);
queue_delayed_work(afs_wq, &afs_vlocation_reap,
delay);
}
break;
}
spin_lock(&vl->cell->vl_lock);
if (atomic_read(&vl->usage) > 0) {
_debug("no reap");
list_del_init(&vl->grave);
} else {
_debug("reap");
list_move_tail(&vl->grave, &corpses);
list_del_init(&vl->link);
}
spin_unlock(&vl->cell->vl_lock);
}
spin_unlock(&afs_vlocation_graveyard_lock);
/* now reap the corpses we've extracted */
while (!list_empty(&corpses)) {
vl = list_entry(corpses.next, struct afs_vlocation, grave);
list_del(&vl->grave);
afs_vlocation_destroy(vl);
}
_leave("");
}
/*
* initialise the VL update process
*/
int __init afs_vlocation_update_init(void)
{
afs_vlocation_update_worker =
create_singlethread_workqueue("kafs_vlupdated");
return afs_vlocation_update_worker ? 0 : -ENOMEM;
}
/*
* discard all the volume location records for rmmod
*/
void afs_vlocation_purge(void)
{
afs_vlocation_timeout = 0;
spin_lock(&afs_vlocation_updates_lock);
list_del_init(&afs_vlocation_updates);
spin_unlock(&afs_vlocation_updates_lock);
cancel_delayed_work(&afs_vlocation_update);
queue_delayed_work(afs_vlocation_update_worker,
&afs_vlocation_update, 0);
destroy_workqueue(afs_vlocation_update_worker);
cancel_delayed_work(&afs_vlocation_reap);
queue_delayed_work(afs_wq, &afs_vlocation_reap, 0);
}
/*
* update a volume location
*/
static void afs_vlocation_updater(struct work_struct *work)
{
struct afs_cache_vlocation vldb;
struct afs_vlocation *vl, *xvl;
time_t now;
long timeout;
int ret;
_enter("");
now = get_seconds();
/* find a record to update */
spin_lock(&afs_vlocation_updates_lock);
for (;;) {
if (list_empty(&afs_vlocation_updates)) {
spin_unlock(&afs_vlocation_updates_lock);
_leave(" [nothing]");
return;
}
vl = list_entry(afs_vlocation_updates.next,
struct afs_vlocation, update);
if (atomic_read(&vl->usage) > 0)
break;
list_del_init(&vl->update);
}
timeout = vl->update_at - now;
if (timeout > 0) {
queue_delayed_work(afs_vlocation_update_worker,
&afs_vlocation_update, timeout * HZ);
spin_unlock(&afs_vlocation_updates_lock);
_leave(" [nothing]");
return;
}
list_del_init(&vl->update);
atomic_inc(&vl->usage);
spin_unlock(&afs_vlocation_updates_lock);
/* we can now perform the update */
_debug("update %s", vl->vldb.name);
vl->state = AFS_VL_UPDATING;
vl->upd_rej_cnt = 0;
vl->upd_busy_cnt = 0;
ret = afs_vlocation_update_record(vl, NULL, &vldb);
spin_lock(&vl->lock);
switch (ret) {
case 0:
afs_vlocation_apply_update(vl, &vldb);
vl->state = AFS_VL_VALID;
break;
case -ENOMEDIUM:
vl->state = AFS_VL_VOLUME_DELETED;
break;
default:
vl->state = AFS_VL_UNCERTAIN;
break;
}
spin_unlock(&vl->lock);
wake_up(&vl->waitq);
/* and then reschedule */
_debug("reschedule");
vl->update_at = get_seconds() + afs_vlocation_update_timeout;
spin_lock(&afs_vlocation_updates_lock);
if (!list_empty(&afs_vlocation_updates)) {
/* next update in 10 minutes, but wait at least 1 second more
* than the newest record already queued so that we don't spam
* the VL server suddenly with lots of requests
*/
xvl = list_entry(afs_vlocation_updates.prev,
struct afs_vlocation, update);
if (vl->update_at <= xvl->update_at)
vl->update_at = xvl->update_at + 1;
xvl = list_entry(afs_vlocation_updates.next,
struct afs_vlocation, update);
timeout = xvl->update_at - now;
if (timeout < 0)
timeout = 0;
} else {
timeout = afs_vlocation_update_timeout;
}
ASSERT(list_empty(&vl->update));
list_add_tail(&vl->update, &afs_vlocation_updates);
_debug("timeout %ld", timeout);
queue_delayed_work(afs_vlocation_update_worker,
&afs_vlocation_update, timeout * HZ);
spin_unlock(&afs_vlocation_updates_lock);
afs_put_vlocation(vl);
}