1 files changed, 322 insertions, 0 deletions
diff --git a/fs/afs/server.c b/fs/afs/server.c
new file mode 100644
index 000000000..f342acf35
--- /dev/null
+++ b/fs/afs/server.c
@@ -0,0 +1,322 @@
+/* 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);
+}