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![Tejun Heo](/assets/img/avatar_default.png)
flush_scheduled_work() is going away. afs needs to make sure all the works it has queued have finished before being unloaded and there can be arbitrary number of pending works. Add afs_wq and use it as the flush domain instead of the system workqueue. Also, convert cancel_delayed_work() + flush_scheduled_work() to cancel_delayed_work_sync() in afs_mntpt_kill_timer(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Cc: linux-afs@lists.infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
328 lines
7.9 KiB
C
328 lines
7.9 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 "internal.h"
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static unsigned afs_server_timeout = 10; /* server timeout in seconds */
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static void afs_reap_server(struct work_struct *);
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/* tree of all the servers, indexed by IP address */
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static struct rb_root afs_servers = RB_ROOT;
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static DEFINE_RWLOCK(afs_servers_lock);
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/* LRU list of all the servers not currently in use */
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static LIST_HEAD(afs_server_graveyard);
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static DEFINE_SPINLOCK(afs_server_graveyard_lock);
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static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);
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/*
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* install a server record in the master tree
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*/
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static int afs_install_server(struct afs_server *server)
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{
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struct afs_server *xserver;
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struct rb_node **pp, *p;
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int ret;
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_enter("%p", server);
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write_lock(&afs_servers_lock);
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ret = -EEXIST;
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pp = &afs_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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xserver = rb_entry(p, struct afs_server, master_rb);
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if (server->addr.s_addr < xserver->addr.s_addr)
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pp = &(*pp)->rb_left;
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else if (server->addr.s_addr > xserver->addr.s_addr)
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pp = &(*pp)->rb_right;
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else
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goto error;
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}
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rb_link_node(&server->master_rb, p, pp);
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rb_insert_color(&server->master_rb, &afs_servers);
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ret = 0;
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error:
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write_unlock(&afs_servers_lock);
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return ret;
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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_cell *cell,
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const struct in_addr *addr)
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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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atomic_set(&server->usage, 1);
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server->cell = cell;
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INIT_LIST_HEAD(&server->link);
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INIT_LIST_HEAD(&server->grave);
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init_rwsem(&server->sem);
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spin_lock_init(&server->fs_lock);
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server->fs_vnodes = RB_ROOT;
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server->cb_promises = RB_ROOT;
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spin_lock_init(&server->cb_lock);
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init_waitqueue_head(&server->cb_break_waitq);
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INIT_DELAYED_WORK(&server->cb_break_work,
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afs_dispatch_give_up_callbacks);
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memcpy(&server->addr, addr, sizeof(struct in_addr));
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server->addr.s_addr = addr->s_addr;
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_leave(" = %p{%d}", server, atomic_read(&server->usage));
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} else {
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_leave(" = NULL [nomem]");
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}
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return server;
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}
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/*
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* get an FS-server record for a cell
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*/
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struct afs_server *afs_lookup_server(struct afs_cell *cell,
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const struct in_addr *addr)
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{
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struct afs_server *server, *candidate;
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_enter("%p,%pI4", cell, &addr->s_addr);
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/* quick scan of the list to see if we already have the server */
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read_lock(&cell->servers_lock);
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list_for_each_entry(server, &cell->servers, link) {
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if (server->addr.s_addr == addr->s_addr)
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goto found_server_quickly;
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}
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read_unlock(&cell->servers_lock);
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candidate = afs_alloc_server(cell, addr);
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if (!candidate) {
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_leave(" = -ENOMEM");
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return ERR_PTR(-ENOMEM);
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}
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write_lock(&cell->servers_lock);
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/* check the cell's server list again */
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list_for_each_entry(server, &cell->servers, link) {
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if (server->addr.s_addr == addr->s_addr)
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goto found_server;
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}
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_debug("new");
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server = candidate;
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if (afs_install_server(server) < 0)
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goto server_in_two_cells;
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afs_get_cell(cell);
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list_add_tail(&server->link, &cell->servers);
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write_unlock(&cell->servers_lock);
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_leave(" = %p{%d}", server, atomic_read(&server->usage));
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return server;
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/* found a matching server quickly */
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found_server_quickly:
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_debug("found quickly");
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afs_get_server(server);
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read_unlock(&cell->servers_lock);
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no_longer_unused:
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if (!list_empty(&server->grave)) {
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spin_lock(&afs_server_graveyard_lock);
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list_del_init(&server->grave);
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spin_unlock(&afs_server_graveyard_lock);
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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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/* found a matching server on the second pass */
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found_server:
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_debug("found");
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afs_get_server(server);
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write_unlock(&cell->servers_lock);
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kfree(candidate);
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goto no_longer_unused;
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/* found a server that seems to be in two cells */
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server_in_two_cells:
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write_unlock(&cell->servers_lock);
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kfree(candidate);
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printk(KERN_NOTICE "kAFS: Server %pI4 appears to be in two cells\n",
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addr);
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_leave(" = -EEXIST");
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return ERR_PTR(-EEXIST);
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}
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/*
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* look up a server by its IP address
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*/
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struct afs_server *afs_find_server(const struct in_addr *_addr)
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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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struct in_addr addr = *_addr;
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_enter("%pI4", &addr.s_addr);
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read_lock(&afs_servers_lock);
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p = afs_servers.rb_node;
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while (p) {
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server = rb_entry(p, struct afs_server, master_rb);
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_debug("- consider %p", p);
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if (addr.s_addr < server->addr.s_addr) {
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p = p->rb_left;
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} else if (addr.s_addr > server->addr.s_addr) {
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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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goto found;
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}
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}
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server = NULL;
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found:
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read_unlock(&afs_servers_lock);
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ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
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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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* destroy a server record
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* - removes from the cell list
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*/
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void afs_put_server(struct afs_server *server)
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{
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if (!server)
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return;
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_enter("%p{%d}", server, atomic_read(&server->usage));
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_debug("PUT SERVER %d", atomic_read(&server->usage));
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ASSERTCMP(atomic_read(&server->usage), >, 0);
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if (likely(!atomic_dec_and_test(&server->usage))) {
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_leave("");
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return;
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}
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afs_flush_callback_breaks(server);
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spin_lock(&afs_server_graveyard_lock);
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if (atomic_read(&server->usage) == 0) {
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list_move_tail(&server->grave, &afs_server_graveyard);
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server->time_of_death = get_seconds();
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queue_delayed_work(afs_wq, &afs_server_reaper,
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afs_server_timeout * HZ);
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}
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spin_unlock(&afs_server_graveyard_lock);
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_leave(" [dead]");
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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_server *server)
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{
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_enter("%p", server);
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ASSERTIF(server->cb_break_head != server->cb_break_tail,
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delayed_work_pending(&server->cb_break_work));
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ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
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ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
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ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
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ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
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afs_put_cell(server->cell);
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kfree(server);
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}
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/*
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* reap dead server records
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*/
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static void afs_reap_server(struct work_struct *work)
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{
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LIST_HEAD(corpses);
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struct afs_server *server;
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unsigned long delay, expiry;
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time_t now;
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now = get_seconds();
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spin_lock(&afs_server_graveyard_lock);
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while (!list_empty(&afs_server_graveyard)) {
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server = list_entry(afs_server_graveyard.next,
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struct afs_server, grave);
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/* the queue is ordered most dead first */
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expiry = server->time_of_death + afs_server_timeout;
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if (expiry > now) {
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delay = (expiry - now) * HZ;
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if (!queue_delayed_work(afs_wq, &afs_server_reaper,
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delay)) {
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cancel_delayed_work(&afs_server_reaper);
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queue_delayed_work(afs_wq, &afs_server_reaper,
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delay);
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}
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break;
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}
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write_lock(&server->cell->servers_lock);
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write_lock(&afs_servers_lock);
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if (atomic_read(&server->usage) > 0) {
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list_del_init(&server->grave);
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} else {
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list_move_tail(&server->grave, &corpses);
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list_del_init(&server->link);
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rb_erase(&server->master_rb, &afs_servers);
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}
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write_unlock(&afs_servers_lock);
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write_unlock(&server->cell->servers_lock);
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}
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spin_unlock(&afs_server_graveyard_lock);
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/* now reap the corpses we've extracted */
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while (!list_empty(&corpses)) {
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server = list_entry(corpses.next, struct afs_server, grave);
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list_del(&server->grave);
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afs_destroy_server(server);
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}
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}
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/*
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* discard all the server records for rmmod
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*/
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void __exit afs_purge_servers(void)
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{
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afs_server_timeout = 0;
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cancel_delayed_work(&afs_server_reaper);
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queue_delayed_work(afs_wq, &afs_server_reaper, 0);
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}
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