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![David Howells](/assets/img/avatar_default.png)
At the moment, afs_break_callbacks calls afs_break_one_callback() for each separate FID it was given, and the latter looks up the volume individually for each one. However, this is inefficient if two or more FIDs have the same vid as we could reuse the volume. This is complicated by cell aliasing whereby we may have multiple cells sharing a volume and can therefore have multiple callback interests for any particular volume ID. At the moment afs_break_one_callback() scans the entire list of volumes we're getting from a server and breaks the appropriate callback in every matching volume, regardless of cell. This scan is done for every FID. Optimise callback breaking by the following means: (1) Sort the FID list by vid so that all FIDs belonging to the same volume are clumped together. This is done through the use of an indirection table as we cannot do an insertion sort on the afs_callback_break array as we decode FIDs into it as we subsequently also have to decode callback info into it that corresponds by array index only. We also don't really want to bubblesort afterwards if we can avoid it. (2) Sort the server->cb_interests array by vid so that all the matching volumes are grouped together. This permits the scan to stop after finding a record that has a higher vid. (3) When breaking FIDs, we try to keep server->cb_break_lock as long as possible, caching the start point in the array for that volume group as long as possible. It might make sense to add another layer in that list and have a refcounted volume ID anchor that has the matching interests attached to it rather than being in the list. This would allow the lock to be dropped without losing the cursor. Signed-off-by: David Howells <dhowells@redhat.com>
697 lines
17 KiB
C
697 lines
17 KiB
C
/* AFS server record management
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*
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* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include "afs_fs.h"
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#include "internal.h"
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static unsigned afs_server_gc_delay = 10; /* Server record timeout in seconds */
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static unsigned afs_server_update_delay = 30; /* Time till VLDB recheck in secs */
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static void afs_inc_servers_outstanding(struct afs_net *net)
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{
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atomic_inc(&net->servers_outstanding);
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}
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static void afs_dec_servers_outstanding(struct afs_net *net)
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{
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if (atomic_dec_and_test(&net->servers_outstanding))
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wake_up_var(&net->servers_outstanding);
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}
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/*
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* Find a server by one of its addresses.
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*/
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struct afs_server *afs_find_server(struct afs_net *net,
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const struct sockaddr_rxrpc *srx)
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{
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const struct sockaddr_in6 *a = &srx->transport.sin6, *b;
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const struct afs_addr_list *alist;
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struct afs_server *server = NULL;
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unsigned int i;
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bool ipv6 = true;
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int seq = 0, diff;
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if (srx->transport.sin6.sin6_addr.s6_addr32[0] == 0 ||
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srx->transport.sin6.sin6_addr.s6_addr32[1] == 0 ||
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srx->transport.sin6.sin6_addr.s6_addr32[2] == htonl(0xffff))
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ipv6 = false;
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rcu_read_lock();
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do {
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if (server)
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afs_put_server(net, server);
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server = NULL;
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read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
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if (ipv6) {
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hlist_for_each_entry_rcu(server, &net->fs_addresses6, addr6_link) {
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alist = rcu_dereference(server->addresses);
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for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
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b = &alist->addrs[i].transport.sin6;
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diff = ((u16 __force)a->sin6_port -
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(u16 __force)b->sin6_port);
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if (diff == 0)
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diff = memcmp(&a->sin6_addr,
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&b->sin6_addr,
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sizeof(struct in6_addr));
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if (diff == 0)
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goto found;
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}
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}
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} else {
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hlist_for_each_entry_rcu(server, &net->fs_addresses4, addr4_link) {
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alist = rcu_dereference(server->addresses);
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for (i = 0; i < alist->nr_ipv4; i++) {
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b = &alist->addrs[i].transport.sin6;
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diff = ((u16 __force)a->sin6_port -
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(u16 __force)b->sin6_port);
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if (diff == 0)
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diff = ((u32 __force)a->sin6_addr.s6_addr32[3] -
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(u32 __force)b->sin6_addr.s6_addr32[3]);
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if (diff == 0)
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goto found;
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}
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}
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}
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server = NULL;
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found:
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if (server && !atomic_inc_not_zero(&server->usage))
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server = NULL;
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} while (need_seqretry(&net->fs_addr_lock, seq));
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done_seqretry(&net->fs_addr_lock, seq);
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rcu_read_unlock();
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return server;
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}
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/*
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* Look up a server by its UUID
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*/
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struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uuid)
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{
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struct afs_server *server = NULL;
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struct rb_node *p;
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int diff, seq = 0;
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_enter("%pU", uuid);
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do {
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/* Unfortunately, rbtree walking doesn't give reliable results
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* under just the RCU read lock, so we have to check for
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* changes.
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*/
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if (server)
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afs_put_server(net, server);
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server = NULL;
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read_seqbegin_or_lock(&net->fs_lock, &seq);
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p = net->fs_servers.rb_node;
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while (p) {
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server = rb_entry(p, struct afs_server, uuid_rb);
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diff = memcmp(uuid, &server->uuid, sizeof(*uuid));
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if (diff < 0) {
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p = p->rb_left;
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} else if (diff > 0) {
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p = p->rb_right;
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} else {
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afs_get_server(server);
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break;
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}
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server = NULL;
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}
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} while (need_seqretry(&net->fs_lock, seq));
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done_seqretry(&net->fs_lock, seq);
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_leave(" = %p", server);
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return server;
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}
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/*
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* Install a server record in the namespace tree
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*/
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static struct afs_server *afs_install_server(struct afs_net *net,
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struct afs_server *candidate)
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{
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const struct afs_addr_list *alist;
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struct afs_server *server;
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struct rb_node **pp, *p;
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int ret = -EEXIST, diff;
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_enter("%p", candidate);
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write_seqlock(&net->fs_lock);
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/* Firstly install the server in the UUID lookup tree */
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pp = &net->fs_servers.rb_node;
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p = NULL;
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while (*pp) {
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p = *pp;
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_debug("- consider %p", p);
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server = rb_entry(p, struct afs_server, uuid_rb);
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diff = memcmp(&candidate->uuid, &server->uuid, sizeof(uuid_t));
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if (diff < 0)
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pp = &(*pp)->rb_left;
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else if (diff > 0)
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pp = &(*pp)->rb_right;
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else
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goto exists;
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}
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server = candidate;
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rb_link_node(&server->uuid_rb, p, pp);
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rb_insert_color(&server->uuid_rb, &net->fs_servers);
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hlist_add_head_rcu(&server->proc_link, &net->fs_proc);
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write_seqlock(&net->fs_addr_lock);
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alist = rcu_dereference_protected(server->addresses,
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lockdep_is_held(&net->fs_addr_lock.lock));
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/* Secondly, if the server has any IPv4 and/or IPv6 addresses, install
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* it in the IPv4 and/or IPv6 reverse-map lists.
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*
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* TODO: For speed we want to use something other than a flat list
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* here; even sorting the list in terms of lowest address would help a
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* bit, but anything we might want to do gets messy and memory
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* intensive.
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*/
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if (alist->nr_ipv4 > 0)
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hlist_add_head_rcu(&server->addr4_link, &net->fs_addresses4);
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if (alist->nr_addrs > alist->nr_ipv4)
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hlist_add_head_rcu(&server->addr6_link, &net->fs_addresses6);
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write_sequnlock(&net->fs_addr_lock);
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ret = 0;
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exists:
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afs_get_server(server);
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write_sequnlock(&net->fs_lock);
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return server;
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}
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/*
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* allocate a new server record
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*/
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static struct afs_server *afs_alloc_server(struct afs_net *net,
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const uuid_t *uuid,
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struct afs_addr_list *alist)
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{
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struct afs_server *server;
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_enter("");
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server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
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if (!server)
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goto enomem;
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atomic_set(&server->usage, 1);
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RCU_INIT_POINTER(server->addresses, alist);
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server->addr_version = alist->version;
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server->uuid = *uuid;
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server->flags = (1UL << AFS_SERVER_FL_NEW);
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server->update_at = ktime_get_real_seconds() + afs_server_update_delay;
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rwlock_init(&server->fs_lock);
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INIT_HLIST_HEAD(&server->cb_volumes);
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rwlock_init(&server->cb_break_lock);
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afs_inc_servers_outstanding(net);
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_leave(" = %p", server);
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return server;
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enomem:
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_leave(" = NULL [nomem]");
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return NULL;
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}
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/*
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* Look up an address record for a server
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*/
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static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell,
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struct key *key, const uuid_t *uuid)
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{
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struct afs_addr_cursor ac;
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struct afs_addr_list *alist;
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int ret;
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ret = afs_set_vl_cursor(&ac, cell);
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if (ret < 0)
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return ERR_PTR(ret);
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while (afs_iterate_addresses(&ac)) {
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if (test_bit(ac.index, &ac.alist->yfs))
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alist = afs_yfsvl_get_endpoints(cell->net, &ac, key, uuid);
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else
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alist = afs_vl_get_addrs_u(cell->net, &ac, key, uuid);
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switch (ac.error) {
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case 0:
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afs_end_cursor(&ac);
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return alist;
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case -ECONNABORTED:
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ac.error = afs_abort_to_error(ac.abort_code);
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goto error;
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case -ENOMEM:
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case -ENONET:
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goto error;
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case -ENETUNREACH:
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case -EHOSTUNREACH:
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case -ECONNREFUSED:
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break;
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default:
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ac.error = -EIO;
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goto error;
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}
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}
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error:
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return ERR_PTR(afs_end_cursor(&ac));
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}
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/*
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* Get or create a fileserver record.
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*/
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struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
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const uuid_t *uuid)
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{
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struct afs_addr_list *alist;
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struct afs_server *server, *candidate;
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_enter("%p,%pU", cell->net, uuid);
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server = afs_find_server_by_uuid(cell->net, uuid);
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if (server)
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return server;
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alist = afs_vl_lookup_addrs(cell, key, uuid);
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if (IS_ERR(alist))
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return ERR_CAST(alist);
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candidate = afs_alloc_server(cell->net, uuid, alist);
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if (!candidate) {
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afs_put_addrlist(alist);
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return ERR_PTR(-ENOMEM);
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}
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server = afs_install_server(cell->net, candidate);
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if (server != candidate) {
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afs_put_addrlist(alist);
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kfree(candidate);
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}
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_leave(" = %p{%d}", server, atomic_read(&server->usage));
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return server;
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}
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/*
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* Set the server timer to fire after a given delay, assuming it's not already
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* set for an earlier time.
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*/
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static void afs_set_server_timer(struct afs_net *net, time64_t delay)
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{
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if (net->live) {
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afs_inc_servers_outstanding(net);
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if (timer_reduce(&net->fs_timer, jiffies + delay * HZ))
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afs_dec_servers_outstanding(net);
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}
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}
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/*
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* Server management timer. We have an increment on fs_outstanding that we
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* need to pass along to the work item.
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*/
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void afs_servers_timer(struct timer_list *timer)
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{
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struct afs_net *net = container_of(timer, struct afs_net, fs_timer);
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_enter("");
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if (!queue_work(afs_wq, &net->fs_manager))
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afs_dec_servers_outstanding(net);
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}
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/*
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* Release a reference on a server record.
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*/
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void afs_put_server(struct afs_net *net, struct afs_server *server)
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{
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unsigned int usage;
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if (!server)
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return;
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server->put_time = ktime_get_real_seconds();
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usage = atomic_dec_return(&server->usage);
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_enter("{%u}", usage);
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if (likely(usage > 0))
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return;
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afs_set_server_timer(net, afs_server_gc_delay);
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}
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static void afs_server_rcu(struct rcu_head *rcu)
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{
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struct afs_server *server = container_of(rcu, struct afs_server, rcu);
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afs_put_addrlist(rcu_access_pointer(server->addresses));
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kfree(server);
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}
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/*
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* destroy a dead server
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*/
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static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
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{
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struct afs_addr_list *alist = rcu_access_pointer(server->addresses);
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struct afs_addr_cursor ac = {
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.alist = alist,
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.start = alist->index,
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.index = 0,
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.addr = &alist->addrs[alist->index],
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.error = 0,
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};
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_enter("%p", server);
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if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))
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afs_fs_give_up_all_callbacks(net, server, &ac, NULL);
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call_rcu(&server->rcu, afs_server_rcu);
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afs_dec_servers_outstanding(net);
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}
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/*
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* Garbage collect any expired servers.
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*/
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static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
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{
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struct afs_server *server;
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bool deleted;
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int usage;
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while ((server = gc_list)) {
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gc_list = server->gc_next;
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write_seqlock(&net->fs_lock);
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usage = 1;
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deleted = atomic_try_cmpxchg(&server->usage, &usage, 0);
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if (deleted) {
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rb_erase(&server->uuid_rb, &net->fs_servers);
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hlist_del_rcu(&server->proc_link);
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}
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write_sequnlock(&net->fs_lock);
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if (deleted) {
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write_seqlock(&net->fs_addr_lock);
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if (!hlist_unhashed(&server->addr4_link))
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hlist_del_rcu(&server->addr4_link);
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if (!hlist_unhashed(&server->addr6_link))
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hlist_del_rcu(&server->addr6_link);
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write_sequnlock(&net->fs_addr_lock);
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afs_destroy_server(net, server);
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}
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}
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}
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/*
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* Manage the records of servers known to be within a network namespace. This
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* includes garbage collecting unused servers.
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*
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* Note also that we were given an increment on net->servers_outstanding by
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* whoever queued us that we need to deal with before returning.
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*/
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void afs_manage_servers(struct work_struct *work)
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{
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struct afs_net *net = container_of(work, struct afs_net, fs_manager);
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struct afs_server *gc_list = NULL;
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struct rb_node *cursor;
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time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX;
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bool purging = !net->live;
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_enter("");
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/* Trawl the server list looking for servers that have expired from
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* lack of use.
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*/
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read_seqlock_excl(&net->fs_lock);
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for (cursor = rb_first(&net->fs_servers); cursor; cursor = rb_next(cursor)) {
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struct afs_server *server =
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rb_entry(cursor, struct afs_server, uuid_rb);
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int usage = atomic_read(&server->usage);
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_debug("manage %pU %u", &server->uuid, usage);
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ASSERTCMP(usage, >=, 1);
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ASSERTIFCMP(purging, usage, ==, 1);
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if (usage == 1) {
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time64_t expire_at = server->put_time;
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if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) &&
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!test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags))
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expire_at += afs_server_gc_delay;
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if (purging || expire_at <= now) {
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server->gc_next = gc_list;
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gc_list = server;
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} else if (expire_at < next_manage) {
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next_manage = expire_at;
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}
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}
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}
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read_sequnlock_excl(&net->fs_lock);
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/* Update the timer on the way out. We have to pass an increment on
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* servers_outstanding in the namespace that we are in to the timer or
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* the work scheduler.
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*/
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if (!purging && next_manage < TIME64_MAX) {
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now = ktime_get_real_seconds();
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|
|
if (next_manage - now <= 0) {
|
|
if (queue_work(afs_wq, &net->fs_manager))
|
|
afs_inc_servers_outstanding(net);
|
|
} else {
|
|
afs_set_server_timer(net, next_manage - now);
|
|
}
|
|
}
|
|
|
|
afs_gc_servers(net, gc_list);
|
|
|
|
afs_dec_servers_outstanding(net);
|
|
_leave(" [%d]", atomic_read(&net->servers_outstanding));
|
|
}
|
|
|
|
static void afs_queue_server_manager(struct afs_net *net)
|
|
{
|
|
afs_inc_servers_outstanding(net);
|
|
if (!queue_work(afs_wq, &net->fs_manager))
|
|
afs_dec_servers_outstanding(net);
|
|
}
|
|
|
|
/*
|
|
* Purge list of servers.
|
|
*/
|
|
void afs_purge_servers(struct afs_net *net)
|
|
{
|
|
_enter("");
|
|
|
|
if (del_timer_sync(&net->fs_timer))
|
|
atomic_dec(&net->servers_outstanding);
|
|
|
|
afs_queue_server_manager(net);
|
|
|
|
_debug("wait");
|
|
wait_var_event(&net->servers_outstanding,
|
|
!atomic_read(&net->servers_outstanding));
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* Probe a fileserver to find its capabilities.
|
|
*
|
|
* TODO: Try service upgrade.
|
|
*/
|
|
static bool afs_do_probe_fileserver(struct afs_fs_cursor *fc)
|
|
{
|
|
_enter("");
|
|
|
|
fc->ac.addr = NULL;
|
|
fc->ac.start = READ_ONCE(fc->ac.alist->index);
|
|
fc->ac.index = fc->ac.start;
|
|
fc->ac.error = 0;
|
|
fc->ac.begun = false;
|
|
|
|
while (afs_iterate_addresses(&fc->ac)) {
|
|
afs_fs_get_capabilities(afs_v2net(fc->vnode), fc->cbi->server,
|
|
&fc->ac, fc->key);
|
|
switch (fc->ac.error) {
|
|
case 0:
|
|
afs_end_cursor(&fc->ac);
|
|
set_bit(AFS_SERVER_FL_PROBED, &fc->cbi->server->flags);
|
|
return true;
|
|
case -ECONNABORTED:
|
|
fc->ac.error = afs_abort_to_error(fc->ac.abort_code);
|
|
goto error;
|
|
case -ENOMEM:
|
|
case -ENONET:
|
|
goto error;
|
|
case -ENETUNREACH:
|
|
case -EHOSTUNREACH:
|
|
case -ECONNREFUSED:
|
|
case -ETIMEDOUT:
|
|
case -ETIME:
|
|
break;
|
|
default:
|
|
fc->ac.error = -EIO;
|
|
goto error;
|
|
}
|
|
}
|
|
|
|
error:
|
|
afs_end_cursor(&fc->ac);
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* If we haven't already, try probing the fileserver to get its capabilities.
|
|
* We try not to instigate parallel probes, but it's possible that the parallel
|
|
* probes will fail due to authentication failure when ours would succeed.
|
|
*
|
|
* TODO: Try sending an anonymous probe if an authenticated probe fails.
|
|
*/
|
|
bool afs_probe_fileserver(struct afs_fs_cursor *fc)
|
|
{
|
|
bool success;
|
|
int ret, retries = 0;
|
|
|
|
_enter("");
|
|
|
|
retry:
|
|
if (test_bit(AFS_SERVER_FL_PROBED, &fc->cbi->server->flags)) {
|
|
_leave(" = t");
|
|
return true;
|
|
}
|
|
|
|
if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &fc->cbi->server->flags)) {
|
|
success = afs_do_probe_fileserver(fc);
|
|
clear_bit_unlock(AFS_SERVER_FL_PROBING, &fc->cbi->server->flags);
|
|
wake_up_bit(&fc->cbi->server->flags, AFS_SERVER_FL_PROBING);
|
|
_leave(" = t");
|
|
return success;
|
|
}
|
|
|
|
_debug("wait");
|
|
ret = wait_on_bit(&fc->cbi->server->flags, AFS_SERVER_FL_PROBING,
|
|
TASK_INTERRUPTIBLE);
|
|
if (ret == -ERESTARTSYS) {
|
|
fc->ac.error = ret;
|
|
_leave(" = f [%d]", ret);
|
|
return false;
|
|
}
|
|
|
|
retries++;
|
|
if (retries == 4) {
|
|
fc->ac.error = -ESTALE;
|
|
_leave(" = f [stale]");
|
|
return false;
|
|
}
|
|
_debug("retry");
|
|
goto retry;
|
|
}
|
|
|
|
/*
|
|
* Get an update for a server's address list.
|
|
*/
|
|
static noinline bool afs_update_server_record(struct afs_fs_cursor *fc, struct afs_server *server)
|
|
{
|
|
struct afs_addr_list *alist, *discard;
|
|
|
|
_enter("");
|
|
|
|
alist = afs_vl_lookup_addrs(fc->vnode->volume->cell, fc->key,
|
|
&server->uuid);
|
|
if (IS_ERR(alist)) {
|
|
fc->ac.error = PTR_ERR(alist);
|
|
_leave(" = f [%d]", fc->ac.error);
|
|
return false;
|
|
}
|
|
|
|
discard = alist;
|
|
if (server->addr_version != alist->version) {
|
|
write_lock(&server->fs_lock);
|
|
discard = rcu_dereference_protected(server->addresses,
|
|
lockdep_is_held(&server->fs_lock));
|
|
rcu_assign_pointer(server->addresses, alist);
|
|
server->addr_version = alist->version;
|
|
write_unlock(&server->fs_lock);
|
|
}
|
|
|
|
server->update_at = ktime_get_real_seconds() + afs_server_update_delay;
|
|
afs_put_addrlist(discard);
|
|
_leave(" = t");
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* See if a server's address list needs updating.
|
|
*/
|
|
bool afs_check_server_record(struct afs_fs_cursor *fc, struct afs_server *server)
|
|
{
|
|
time64_t now = ktime_get_real_seconds();
|
|
long diff;
|
|
bool success;
|
|
int ret, retries = 0;
|
|
|
|
_enter("");
|
|
|
|
ASSERT(server);
|
|
|
|
retry:
|
|
diff = READ_ONCE(server->update_at) - now;
|
|
if (diff > 0) {
|
|
_leave(" = t [not now %ld]", diff);
|
|
return true;
|
|
}
|
|
|
|
if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) {
|
|
success = afs_update_server_record(fc, server);
|
|
clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags);
|
|
wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING);
|
|
_leave(" = %d", success);
|
|
return success;
|
|
}
|
|
|
|
ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING,
|
|
TASK_INTERRUPTIBLE);
|
|
if (ret == -ERESTARTSYS) {
|
|
fc->ac.error = ret;
|
|
_leave(" = f [intr]");
|
|
return false;
|
|
}
|
|
|
|
retries++;
|
|
if (retries == 4) {
|
|
_leave(" = f [stale]");
|
|
ret = -ESTALE;
|
|
return false;
|
|
}
|
|
goto retry;
|
|
}
|