--- /dev/null
+/* AFS server record 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/sched.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+static unsigned afs_server_timeout = 10; /* server timeout in seconds */
+
+static void afs_reap_server(struct work_struct *);
+
+/* tree of all the servers, indexed by IP address */
+static struct rb_root afs_servers = RB_ROOT;
+static DEFINE_RWLOCK(afs_servers_lock);
+
+/* LRU list of all the servers not currently in use */
+static LIST_HEAD(afs_server_graveyard);
+static DEFINE_SPINLOCK(afs_server_graveyard_lock);
+static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);
+
+/*
+ * install a server record in the master tree
+ */
+static int afs_install_server(struct afs_server *server)
+{
+ struct afs_server *xserver;
+ struct rb_node **pp, *p;
+ int ret;
+
+ _enter("%p", server);
+
+ write_lock(&afs_servers_lock);
+
+ ret = -EEXIST;
+ pp = &afs_servers.rb_node;
+ p = NULL;
+ while (*pp) {
+ p = *pp;
+ _debug("- consider %p", p);
+ xserver = rb_entry(p, struct afs_server, master_rb);
+ if (server->addr.s_addr < xserver->addr.s_addr)
+ pp = &(*pp)->rb_left;
+ else if (server->addr.s_addr > xserver->addr.s_addr)
+ pp = &(*pp)->rb_right;
+ else
+ goto error;
+ }
+
+ rb_link_node(&server->master_rb, p, pp);
+ rb_insert_color(&server->master_rb, &afs_servers);
+ ret = 0;
+
+error:
+ write_unlock(&afs_servers_lock);
+ return ret;
+}
+
+/*
+ * allocate a new server record
+ */
+static struct afs_server *afs_alloc_server(struct afs_cell *cell,
+ const struct in_addr *addr)
+{
+ struct afs_server *server;
+
+ _enter("");
+
+ server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
+ if (server) {
+ atomic_set(&server->usage, 1);
+ server->cell = cell;
+
+ INIT_LIST_HEAD(&server->link);
+ INIT_LIST_HEAD(&server->grave);
+ init_rwsem(&server->sem);
+ spin_lock_init(&server->fs_lock);
+ server->fs_vnodes = RB_ROOT;
+ server->cb_promises = RB_ROOT;
+ spin_lock_init(&server->cb_lock);
+ init_waitqueue_head(&server->cb_break_waitq);
+ INIT_DELAYED_WORK(&server->cb_break_work,
+ afs_dispatch_give_up_callbacks);
+
+ memcpy(&server->addr, addr, sizeof(struct in_addr));
+ server->addr.s_addr = addr->s_addr;
+ _leave(" = %p{%d}", server, atomic_read(&server->usage));
+ } else {
+ _leave(" = NULL [nomem]");
+ }
+ return server;
+}
+
+/*
+ * get an FS-server record for a cell
+ */
+struct afs_server *afs_lookup_server(struct afs_cell *cell,
+ const struct in_addr *addr)
+{
+ struct afs_server *server, *candidate;
+
+ _enter("%p,%pI4", cell, &addr->s_addr);
+
+ /* quick scan of the list to see if we already have the server */
+ read_lock(&cell->servers_lock);
+
+ list_for_each_entry(server, &cell->servers, link) {
+ if (server->addr.s_addr == addr->s_addr)
+ goto found_server_quickly;
+ }
+ read_unlock(&cell->servers_lock);
+
+ candidate = afs_alloc_server(cell, addr);
+ if (!candidate) {
+ _leave(" = -ENOMEM");
+ return ERR_PTR(-ENOMEM);
+ }
+
+ write_lock(&cell->servers_lock);
+
+ /* check the cell's server list again */
+ list_for_each_entry(server, &cell->servers, link) {
+ if (server->addr.s_addr == addr->s_addr)
+ goto found_server;
+ }
+
+ _debug("new");
+ server = candidate;
+ if (afs_install_server(server) < 0)
+ goto server_in_two_cells;
+
+ afs_get_cell(cell);
+ list_add_tail(&server->link, &cell->servers);
+
+ write_unlock(&cell->servers_lock);
+ _leave(" = %p{%d}", server, atomic_read(&server->usage));
+ return server;
+
+ /* found a matching server quickly */
+found_server_quickly:
+ _debug("found quickly");
+ afs_get_server(server);
+ read_unlock(&cell->servers_lock);
+no_longer_unused:
+ if (!list_empty(&server->grave)) {
+ spin_lock(&afs_server_graveyard_lock);
+ list_del_init(&server->grave);
+ spin_unlock(&afs_server_graveyard_lock);
+ }
+ _leave(" = %p{%d}", server, atomic_read(&server->usage));
+ return server;
+
+ /* found a matching server on the second pass */
+found_server:
+ _debug("found");
+ afs_get_server(server);
+ write_unlock(&cell->servers_lock);
+ kfree(candidate);
+ goto no_longer_unused;
+
+ /* found a server that seems to be in two cells */
+server_in_two_cells:
+ write_unlock(&cell->servers_lock);
+ kfree(candidate);
+ printk(KERN_NOTICE "kAFS: Server %pI4 appears to be in two cells\n",
+ addr);
+ _leave(" = -EEXIST");
+ return ERR_PTR(-EEXIST);
+}
+
+/*
+ * look up a server by its IP address
+ */
+struct afs_server *afs_find_server(const struct in_addr *_addr)
+{
+ struct afs_server *server = NULL;
+ struct rb_node *p;
+ struct in_addr addr = *_addr;
+
+ _enter("%pI4", &addr.s_addr);
+
+ read_lock(&afs_servers_lock);
+
+ p = afs_servers.rb_node;
+ while (p) {
+ server = rb_entry(p, struct afs_server, master_rb);
+
+ _debug("- consider %p", p);
+
+ if (addr.s_addr < server->addr.s_addr) {
+ p = p->rb_left;
+ } else if (addr.s_addr > server->addr.s_addr) {
+ p = p->rb_right;
+ } else {
+ afs_get_server(server);
+ goto found;
+ }
+ }
+
+ server = NULL;
+found:
+ read_unlock(&afs_servers_lock);
+ ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
+ _leave(" = %p", server);
+ return server;
+}
+
+/*
+ * destroy a server record
+ * - removes from the cell list
+ */
+void afs_put_server(struct afs_server *server)
+{
+ if (!server)
+ return;
+
+ _enter("%p{%d}", server, atomic_read(&server->usage));
+
+ _debug("PUT SERVER %d", atomic_read(&server->usage));
+
+ ASSERTCMP(atomic_read(&server->usage), >, 0);
+
+ if (likely(!atomic_dec_and_test(&server->usage))) {
+ _leave("");
+ return;
+ }
+
+ afs_flush_callback_breaks(server);
+
+ spin_lock(&afs_server_graveyard_lock);
+ if (atomic_read(&server->usage) == 0) {
+ list_move_tail(&server->grave, &afs_server_graveyard);
+ server->time_of_death = get_seconds();
+ queue_delayed_work(afs_wq, &afs_server_reaper,
+ afs_server_timeout * HZ);
+ }
+ spin_unlock(&afs_server_graveyard_lock);
+ _leave(" [dead]");
+}
+
+/*
+ * destroy a dead server
+ */
+static void afs_destroy_server(struct afs_server *server)
+{
+ _enter("%p", server);
+
+ ASSERTIF(server->cb_break_head != server->cb_break_tail,
+ delayed_work_pending(&server->cb_break_work));
+
+ ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
+ ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
+ ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
+ ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
+
+ afs_put_cell(server->cell);
+ kfree(server);
+}
+
+/*
+ * reap dead server records
+ */
+static void afs_reap_server(struct work_struct *work)
+{
+ LIST_HEAD(corpses);
+ struct afs_server *server;
+ unsigned long delay, expiry;
+ time_t now;
+
+ now = get_seconds();
+ spin_lock(&afs_server_graveyard_lock);
+
+ while (!list_empty(&afs_server_graveyard)) {
+ server = list_entry(afs_server_graveyard.next,
+ struct afs_server, grave);
+
+ /* the queue is ordered most dead first */
+ expiry = server->time_of_death + afs_server_timeout;
+ if (expiry > now) {
+ delay = (expiry - now) * HZ;
+ mod_delayed_work(afs_wq, &afs_server_reaper, delay);
+ break;
+ }
+
+ write_lock(&server->cell->servers_lock);
+ write_lock(&afs_servers_lock);
+ if (atomic_read(&server->usage) > 0) {
+ list_del_init(&server->grave);
+ } else {
+ list_move_tail(&server->grave, &corpses);
+ list_del_init(&server->link);
+ rb_erase(&server->master_rb, &afs_servers);
+ }
+ write_unlock(&afs_servers_lock);
+ write_unlock(&server->cell->servers_lock);
+ }
+
+ spin_unlock(&afs_server_graveyard_lock);
+
+ /* now reap the corpses we've extracted */
+ while (!list_empty(&corpses)) {
+ server = list_entry(corpses.next, struct afs_server, grave);
+ list_del(&server->grave);
+ afs_destroy_server(server);
+ }
+}
+
+/*
+ * discard all the server records for rmmod
+ */
+void __exit afs_purge_servers(void)
+{
+ afs_server_timeout = 0;
+ mod_delayed_work(afs_wq, &afs_server_reaper, 0);
+}
Code Review / kvmfornfv.git / blobdiff