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/*
* 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"
/*
* Set up an interest-in-callbacks record for a volume on a server and
* register it with the server.
* - Called with volume->server_sem held.
*/
int afs_register_server_cb_interest(struct afs_vnode *vnode,
struct afs_server_entry *entry)
{
struct afs_cb_interest *cbi = entry->cb_interest, *vcbi, *new, *x;
struct afs_server *server = entry->server;
again:
vcbi = vnode->cb_interest;
if (vcbi) {
if (vcbi == cbi)
return 0;
if (cbi && vcbi->server == cbi->server) {
write_seqlock(&vnode->cb_lock);
vnode->cb_interest = afs_get_cb_interest(cbi);
write_sequnlock(&vnode->cb_lock);
afs_put_cb_interest(afs_v2net(vnode), cbi);
return 0;
}
if (!cbi && vcbi->server == server) {
afs_get_cb_interest(vcbi);
x = cmpxchg(&entry->cb_interest, cbi, vcbi);
if (x != cbi) {
cbi = x;
afs_put_cb_interest(afs_v2net(vnode), vcbi);
goto again;
}
return 0;
}
}
if (!cbi) {
new = kzalloc(sizeof(struct afs_cb_interest), GFP_KERNEL);
if (!new)
return -ENOMEM;
refcount_set(&new->usage, 1);
new->sb = vnode->vfs_inode.i_sb;
new->vid = vnode->volume->vid;
new->server = afs_get_server(server);
INIT_LIST_HEAD(&new->cb_link);
write_lock(&server->cb_break_lock);
list_add_tail(&new->cb_link, &server->cb_interests);
write_unlock(&server->cb_break_lock);
x = cmpxchg(&entry->cb_interest, cbi, new);
if (x == cbi) {
cbi = new;
} else {
cbi = x;
afs_put_cb_interest(afs_v2net(vnode), new);
}
}
ASSERT(cbi);
/* Change the server the vnode is using. This entails scrubbing any
* interest the vnode had in the previous server it was using.
*/
write_seqlock(&vnode->cb_lock);
vnode->cb_interest = afs_get_cb_interest(cbi);
vnode->cb_s_break = cbi->server->cb_s_break;
clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
write_sequnlock(&vnode->cb_lock);
return 0;
}
/*
* Remove an interest on a server.
*/
void afs_put_cb_interest(struct afs_net *net, struct afs_cb_interest *cbi)
{
if (cbi && refcount_dec_and_test(&cbi->usage)) {
if (!list_empty(&cbi->cb_link)) {
write_lock(&cbi->server->cb_break_lock);
list_del_init(&cbi->cb_link);
write_unlock(&cbi->server->cb_break_lock);
afs_put_server(net, cbi->server);
}
kfree(cbi);
}
}
/*
* allow the fileserver to request callback state (re-)initialisation
*/
void afs_init_callback_state(struct afs_server *server)
{
if (!test_and_clear_bit(AFS_SERVER_FL_NEW, &server->flags))
server->cb_s_break++;
}
/*
* actually break a callback
*/
void afs_break_callback(struct afs_vnode *vnode)
{
_enter("");
write_seqlock(&vnode->cb_lock);
if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
vnode->cb_break++;
afs_clear_permits(vnode);
spin_lock(&vnode->lock);
_debug("break callback");
if (list_empty(&vnode->granted_locks) &&
!list_empty(&vnode->pending_locks))
afs_lock_may_be_available(vnode);
spin_unlock(&vnode->lock);
}
write_sequnlock(&vnode->cb_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_cb_interest *cbi;
struct afs_iget_data data;
struct afs_vnode *vnode;
struct inode *inode;
read_lock(&server->cb_break_lock);
/* Step through all interested superblocks. There may be more than one
* because of cell aliasing.
*/
list_for_each_entry(cbi, &server->cb_interests, cb_link) {
if (cbi->vid != fid->vid)
continue;
data.volume = NULL;
data.fid = *fid;
inode = ilookup5_nowait(cbi->sb, fid->vnode, afs_iget5_test, &data);
if (inode) {
vnode = AFS_FS_I(inode);
afs_break_callback(vnode);
iput(inode);
}
}
read_unlock(&server->cb_break_lock);
}
/*
* 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;
}
/*
* Clear the callback interests in a server list.
*/
void afs_clear_callback_interests(struct afs_net *net, struct afs_server_list *slist)
{
int i;
for (i = 0; i < slist->nr_servers; i++) {
afs_put_cb_interest(net, slist->servers[i].cb_interest);
slist->servers[i].cb_interest = NULL;
}
}
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