- 根目录:
- fs
- afs
- callback.c
/*
* Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
*
* This software may be freely redistributed under the terms of the
* GNU General Public License.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Authors: David Woodhouse <dwmw2@infradead.org>
* David Howells <dhowells@redhat.com>
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/circ_buf.h>
#include <linux/sched.h>
#include "internal.h"
#if 0
unsigned afs_vnode_update_timeout = 10;
#endif /* 0 */
#define afs_breakring_space(server) \
CIRC_SPACE((server)->cb_break_head, (server)->cb_break_tail, \
ARRAY_SIZE((server)->cb_break))
//static void afs_callback_updater(struct work_struct *);
static struct workqueue_struct *afs_callback_update_worker;
/*
* allow the fileserver to request callback state (re-)initialisation
*/
void afs_init_callback_state(struct afs_server *server)
{
struct afs_vnode *vnode;
_enter("{%p}", server);
spin_lock(&server->cb_lock);
/* kill all the promises on record from this server */
while (!RB_EMPTY_ROOT(&server->cb_promises)) {
vnode = rb_entry(server->cb_promises.rb_node,
struct afs_vnode, cb_promise);
_debug("UNPROMISE { vid=%x:%u uq=%u}",
vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
rb_erase(&vnode->cb_promise, &server->cb_promises);
vnode->cb_promised = false;
}
spin_unlock(&server->cb_lock);
_leave("");
}
/*
* handle the data invalidation side of a callback being broken
*/
void afs_broken_callback_work(struct work_struct *work)
{
struct afs_vnode *vnode =
container_of(work, struct afs_vnode, cb_broken_work);
_enter("");
if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
return;
/* we're only interested in dealing with a broken callback on *this*
* vnode and only if no-one else has dealt with it yet */
if (!mutex_trylock(&vnode->validate_lock))
return; /* someone else is dealing with it */
if (test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) {
if (S_ISDIR(vnode->vfs_inode.i_mode))
afs_clear_permits(vnode);
if (afs_vnode_fetch_status(vnode, NULL, NULL) < 0)
goto out;
if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
goto out;
/* if the vnode's data version number changed then its contents
* are different */
if (test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags))
afs_zap_data(vnode);
}
out:
mutex_unlock(&vnode->validate_lock);
/* avoid the potential race whereby the mutex_trylock() in this
* function happens again between the clear_bit() and the
* mutex_unlock() */
if (test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) {
_debug("requeue");
queue_work(afs_callback_update_worker, &vnode->cb_broken_work);
}
_leave("");
}
/*
* actually break a callback
*/
static void afs_break_callback(struct afs_server *server,
struct afs_vnode *vnode)
{
_enter("");
set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
if (vnode->cb_promised) {
spin_lock(&vnode->lock);
_debug("break callback");
spin_lock(&server->cb_lock);
if (vnode->cb_promised) {
rb_erase(&vnode->cb_promise, &server->cb_promises);
vnode->cb_promised = false;
}
spin_unlock(&server->cb_lock);
queue_work(afs_callback_update_worker, &vnode->cb_broken_work);
if (list_empty(&vnode->granted_locks) &&
!list_empty(&vnode->pending_locks))
afs_lock_may_be_available(vnode);
spin_unlock(&vnode->lock);
}
}
/*
* allow the fileserver to explicitly break one callback
* - happens when
* - the backing file is changed
* - a lock is released
*/
static void afs_break_one_callback(struct afs_server *server,
struct afs_fid *fid)
{
struct afs_vnode *vnode;
struct rb_node *p;
_debug("find");
spin_lock(&server->fs_lock);
p = server->fs_vnodes.rb_node;
while (p) {
vnode = rb_entry(p, struct afs_vnode, server_rb);
if (fid->vid < vnode->fid.vid)
p = p->rb_left;
else if (fid->vid > vnode->fid.vid)
p = p->rb_right;
else if (fid->vnode < vnode->fid.vnode)
p = p->rb_left;
else if (fid->vnode > vnode->fid.vnode)
p = p->rb_right;
else if (fid->unique < vnode->fid.unique)
p = p->rb_left;
else if (fid->unique > vnode->fid.unique)
p = p->rb_right;
else
goto found;
}
/* not found so we just ignore it (it may have moved to another
* server) */
not_available:
_debug("not avail");
spin_unlock(&server->fs_lock);
_leave("");
return;
found:
_debug("found");
ASSERTCMP(server, ==, vnode->server);
if (!igrab(AFS_VNODE_TO_I(vnode)))
goto not_available;
spin_unlock(&server->fs_lock);
afs_break_callback(server, vnode);
iput(&vnode->vfs_inode);
_leave("");
}
/*
* allow the fileserver to break callback promises
*/
void afs_break_callbacks(struct afs_server *server, size_t count,
struct afs_callback callbacks[])
{
_enter("%p,%zu,", server, count);
ASSERT(server != NULL);
ASSERTCMP(count, <=, AFSCBMAX);
for (; count > 0; callbacks++, count--) {
_debug("- Fid { vl=%08x n=%u u=%u } CB { v=%u x=%u t=%u }",
callbacks->fid.vid,
callbacks->fid.vnode,
callbacks->fid.unique,
callbacks->version,
callbacks->expiry,
callbacks->type
);
afs_break_one_callback(server, &callbacks->fid);
}
_leave("");
return;
}
/*
* record the callback for breaking
* - the caller must hold server->cb_lock
*/
static void afs_do_give_up_callback(struct afs_server *server,
struct afs_vnode *vnode)
{
struct afs_callback *cb;
_enter("%p,%p", server, vnode);
cb = &server->cb_break[server->cb_break_head];
cb->fid = vnode->fid;
cb->version = vnode->cb_version;
cb->expiry = vnode->cb_expiry;
cb->type = vnode->cb_type;
smp_wmb();
server->cb_break_head =
(server->cb_break_head + 1) &
(ARRAY_SIZE(server->cb_break) - 1);
/* defer the breaking of callbacks to try and collect as many as
* possible to ship in one operation */
switch (atomic_inc_return(&server->cb_break_n)) {
case 1 ... AFSCBMAX - 1:
queue_delayed_work(afs_callback_update_worker,
&server->cb_break_work, HZ * 2);
break;
case AFSCBMAX:
afs_flush_callback_breaks(server);
break;
default:
break;
}
ASSERT(server->cb_promises.rb_node != NULL);
rb_erase(&vnode->cb_promise, &server->cb_promises);
vnode->cb_promised = false;
_leave("");
}
/*
* discard the callback on a deleted item
*/
void afs_discard_callback_on_delete(struct afs_vnode *vnode)
{
struct afs_server *server = vnode->server;
_enter("%d", vnode->cb_promised);
if (!vnode->cb_promised) {
_leave(" [not promised]");
return;
}
ASSERT(server != NULL);
spin_lock(&server->cb_lock);
if (vnode->cb_promised) {
ASSERT(server->cb_promises.rb_node != NULL);
rb_erase(&vnode->cb_promise, &server->cb_promises);
vnode->cb_promised = false;
}
spin_unlock(&server->cb_lock);
_leave("");
}
/*
* give up the callback registered for a vnode on the file server when the
* inode is being cleared
*/
void afs_give_up_callback(struct afs_vnode *vnode)
{
struct afs_server *server = vnode->server;
DECLARE_WAITQUEUE(myself, current);
_enter("%d", vnode->cb_promised);
_debug("GIVE UP INODE %p", &vnode->vfs_inode);
if (!vnode->cb_promised) {
_leave(" [not promised]");
return;
}
ASSERT(server != NULL);
spin_lock(&server->cb_lock);
if (vnode->cb_promised && afs_breakring_space(server) == 0) {
add_wait_queue(&server->cb_break_waitq, &myself);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!vnode->cb_promised ||
afs_breakring_space(server) != 0)
break;
spin_unlock(&server->cb_lock);
schedule();
spin_lock(&server->cb_lock);
}
remove_wait_queue(&server->cb_break_waitq, &myself);
__set_current_state(TASK_RUNNING);
}
/* of course, it's always possible for the server to break this vnode's
* callback first... */
if (vnode->cb_promised)
afs_do_give_up_callback(server, vnode);
spin_unlock(&server->cb_lock);
_leave("");
}
/*
* dispatch a deferred give up callbacks operation
*/
void afs_dispatch_give_up_callbacks(struct work_struct *work)
{
struct afs_server *server =
container_of(work, struct afs_server, cb_break_work.work);
_enter("");
/* tell the fileserver to discard the callback promises it has
* - in the event of ENOMEM or some other error, we just forget that we
* had callbacks entirely, and the server will call us later to break
* them
*/
afs_fs_give_up_callbacks(server, &afs_async_call);
}
/*
* flush the outstanding callback breaks on a server
*/
void afs_flush_callback_breaks(struct afs_server *server)
{
cancel_delayed_work(&server->cb_break_work);
queue_delayed_work(afs_callback_update_worker,
&server->cb_break_work, 0);
}
#if 0
/*
* update a bunch of callbacks
*/
static void afs_callback_updater(struct work_struct *work)
{
struct afs_server *server;
struct afs_vnode *vnode, *xvnode;
time_t now;
long timeout;
int ret;
server = container_of(work, struct afs_server, updater);
_enter("");
now = get_seconds();
/* find the first vnode to update */
spin_lock(&server->cb_lock);
for (;;) {
if (RB_EMPTY_ROOT(&server->cb_promises)) {
spin_unlock(&server->cb_lock);
_leave(" [nothing]");
return;
}
vnode = rb_entry(rb_first(&server->cb_promises),
struct afs_vnode, cb_promise);
if (atomic_read(&vnode->usage) > 0)
break;
rb_erase(&vnode->cb_promise, &server->cb_promises);
vnode->cb_promised = false;
}
timeout = vnode->update_at - now;
if (timeout > 0) {
queue_delayed_work(afs_vnode_update_worker,
&afs_vnode_update, timeout * HZ);
spin_unlock(&server->cb_lock);
_leave(" [nothing]");
return;
}
list_del_init(&vnode->update);
atomic_inc(&vnode->usage);
spin_unlock(&server->cb_lock);
/* we can now perform the update */
_debug("update %s", vnode->vldb.name);
vnode->state = AFS_VL_UPDATING;
vnode->upd_rej_cnt = 0;
vnode->upd_busy_cnt = 0;
ret = afs_vnode_update_record(vl, &vldb);
switch (ret) {
case 0:
afs_vnode_apply_update(vl, &vldb);
vnode->state = AFS_VL_UPDATING;
break;
case -ENOMEDIUM:
vnode->state = AFS_VL_VOLUME_DELETED;
break;
default:
vnode->state = AFS_VL_UNCERTAIN;
break;
}
/* and then reschedule */
_debug("reschedule");
vnode->update_at = get_seconds() + afs_vnode_update_timeout;
spin_lock(&server->cb_lock);
if (!list_empty(&server->cb_promises)) {
/* 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
*/
xvnode = list_entry(server->cb_promises.prev,
struct afs_vnode, update);
if (vnode->update_at <= xvnode->update_at)
vnode->update_at = xvnode->update_at + 1;
xvnode = list_entry(server->cb_promises.next,
struct afs_vnode, update);
timeout = xvnode->update_at - now;
if (timeout < 0)
timeout = 0;
} else {
timeout = afs_vnode_update_timeout;
}
list_add_tail(&vnode->update, &server->cb_promises);
_debug("timeout %ld", timeout);
queue_delayed_work(afs_vnode_update_worker,
&afs_vnode_update, timeout * HZ);
spin_unlock(&server->cb_lock);
afs_put_vnode(vl);
}
#endif
/*
* initialise the callback update process
*/
int __init afs_callback_update_init(void)
{
afs_callback_update_worker =
create_singlethread_workqueue("kafs_callbackd");
return afs_callback_update_worker ? 0 : -ENOMEM;
}
/*
* shut down the callback update process
*/
void afs_callback_update_kill(void)
{
destroy_workqueue(afs_callback_update_worker);
}