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linux-next/fs/afs/callback.c
David Howells 5cf9dd55a0 afs: Prospectively look up extra files when doing a single lookup
When afs_lookup() is called, prospectively look up the next 50 uncached
fids also from that same directory and cache the results, rather than just
looking up the one file requested.

This allows us to use the FS.InlineBulkStatus RPC op to increase efficiency
by fetching up to 50 file statuses at a time.

Signed-off-by: David Howells <dhowells@redhat.com>
2018-04-09 21:12:31 +01:00

225 lines
5.3 KiB
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"
/*
* 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_break *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->cb.version,
callbacks->cb.expiry,
callbacks->cb.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;
}
}