/* * 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" #if 0 unsigned afs_vnode_update_timeout = 10; #endif /* 0 */ #define afs_breakring_space(server) \ CIRC_SPACE((server)->cb_break_head, (server)->cb_break_tail, \ ARRAY_SIZE((server)->cb_break)) //static void afs_callback_updater(struct work_struct *); static struct workqueue_struct *afs_callback_update_worker; /* * allow the fileserver to request callback state (re-)initialisation */ void afs_init_callback_state(struct afs_server *server) { struct afs_vnode *vnode; _enter("{%p}", server); spin_lock(&server->cb_lock); /* kill all the promises on record from this server */ while (!RB_EMPTY_ROOT(&server->cb_promises)) { vnode = rb_entry(server->cb_promises.rb_node, struct afs_vnode, cb_promise); _debug("UNPROMISE { vid=%x:%u uq=%u}", vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique); rb_erase(&vnode->cb_promise, &server->cb_promises); vnode->cb_promised = false; } spin_unlock(&server->cb_lock); _leave(""); } /* * handle the data invalidation side of a callback being broken */ void afs_broken_callback_work(struct work_struct *work) { struct afs_vnode *vnode = container_of(work, struct afs_vnode, cb_broken_work); _enter(""); if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) return; /* we're only interested in dealing with a broken callback on *this* * vnode and only if no-one else has dealt with it yet */ if (!mutex_trylock(&vnode->validate_lock)) return; /* someone else is dealing with it */ if (test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) { if (S_ISDIR(vnode->vfs_inode.i_mode)) afs_clear_permits(vnode); if (afs_vnode_fetch_status(vnode, NULL, NULL) < 0) goto out; if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) goto out; /* if the vnode's data version number changed then its contents * are different */ if (test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) afs_zap_data(vnode); } out: mutex_unlock(&vnode->validate_lock); /* avoid the potential race whereby the mutex_trylock() in this * function happens again between the clear_bit() and the * mutex_unlock() */ if (test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) { _debug("requeue"); queue_work(afs_callback_update_worker, &vnode->cb_broken_work); } _leave(""); } /* * actually break a callback */ static void afs_break_callback(struct afs_server *server, struct afs_vnode *vnode) { _enter(""); set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags); if (vnode->cb_promised) { spin_lock(&vnode->lock); _debug("break callback"); spin_lock(&server->cb_lock); if (vnode->cb_promised) { rb_erase(&vnode->cb_promise, &server->cb_promises); vnode->cb_promised = false; } spin_unlock(&server->cb_lock); queue_work(afs_callback_update_worker, &vnode->cb_broken_work); if (list_empty(&vnode->granted_locks) && !list_empty(&vnode->pending_locks)) afs_lock_may_be_available(vnode); spin_unlock(&vnode->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_vnode *vnode; struct rb_node *p; _debug("find"); spin_lock(&server->fs_lock); p = server->fs_vnodes.rb_node; while (p) { vnode = rb_entry(p, struct afs_vnode, server_rb); if (fid->vid < vnode->fid.vid) p = p->rb_left; else if (fid->vid > vnode->fid.vid) p = p->rb_right; else if (fid->vnode < vnode->fid.vnode) p = p->rb_left; else if (fid->vnode > vnode->fid.vnode) p = p->rb_right; else if (fid->unique < vnode->fid.unique) p = p->rb_left; else if (fid->unique > vnode->fid.unique) p = p->rb_right; else goto found; } /* not found so we just ignore it (it may have moved to another * server) */ not_available: _debug("not avail"); spin_unlock(&server->fs_lock); _leave(""); return; found: _debug("found"); ASSERTCMP(server, ==, vnode->server); if (!igrab(AFS_VNODE_TO_I(vnode))) goto not_available; spin_unlock(&server->fs_lock); afs_break_callback(server, vnode); iput(&vnode->vfs_inode); _leave(""); } /* * allow the fileserver to break callback promises */ void afs_break_callbacks(struct afs_server *server, size_t count, struct afs_callback 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->version, callbacks->expiry, callbacks->type ); afs_break_one_callback(server, &callbacks->fid); } _leave(""); return; } /* * record the callback for breaking * - the caller must hold server->cb_lock */ static void afs_do_give_up_callback(struct afs_server *server, struct afs_vnode *vnode) { struct afs_callback *cb; _enter("%p,%p", server, vnode); cb = &server->cb_break[server->cb_break_head]; cb->fid = vnode->fid; cb->version = vnode->cb_version; cb->expiry = vnode->cb_expiry; cb->type = vnode->cb_type; smp_wmb(); server->cb_break_head = (server->cb_break_head + 1) & (ARRAY_SIZE(server->cb_break) - 1); /* defer the breaking of callbacks to try and collect as many as * possible to ship in one operation */ switch (atomic_inc_return(&server->cb_break_n)) { case 1 ... AFSCBMAX - 1: queue_delayed_work(afs_callback_update_worker, &server->cb_break_work, HZ * 2); break; case AFSCBMAX: afs_flush_callback_breaks(server); break; default: break; } ASSERT(server->cb_promises.rb_node != NULL); rb_erase(&vnode->cb_promise, &server->cb_promises); vnode->cb_promised = false; _leave(""); } /* * discard the callback on a deleted item */ void afs_discard_callback_on_delete(struct afs_vnode *vnode) { struct afs_server *server = vnode->server; _enter("%d", vnode->cb_promised); if (!vnode->cb_promised) { _leave(" [not promised]"); return; } ASSERT(server != NULL); spin_lock(&server->cb_lock); if (vnode->cb_promised) { ASSERT(server->cb_promises.rb_node != NULL); rb_erase(&vnode->cb_promise, &server->cb_promises); vnode->cb_promised = false; } spin_unlock(&server->cb_lock); _leave(""); } /* * give up the callback registered for a vnode on the file server when the * inode is being cleared */ void afs_give_up_callback(struct afs_vnode *vnode) { struct afs_server *server = vnode->server; DECLARE_WAITQUEUE(myself, current); _enter("%d", vnode->cb_promised); _debug("GIVE UP INODE %p", &vnode->vfs_inode); if (!vnode->cb_promised) { _leave(" [not promised]"); return; } ASSERT(server != NULL); spin_lock(&server->cb_lock); if (vnode->cb_promised && afs_breakring_space(server) == 0) { add_wait_queue(&server->cb_break_waitq, &myself); for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (!vnode->cb_promised || afs_breakring_space(server) != 0) break; spin_unlock(&server->cb_lock); schedule(); spin_lock(&server->cb_lock); } remove_wait_queue(&server->cb_break_waitq, &myself); __set_current_state(TASK_RUNNING); } /* of course, it's always possible for the server to break this vnode's * callback first... */ if (vnode->cb_promised) afs_do_give_up_callback(server, vnode); spin_unlock(&server->cb_lock); _leave(""); } /* * dispatch a deferred give up callbacks operation */ void afs_dispatch_give_up_callbacks(struct work_struct *work) { struct afs_server *server = container_of(work, struct afs_server, cb_break_work.work); _enter(""); /* tell the fileserver to discard the callback promises it has * - in the event of ENOMEM or some other error, we just forget that we * had callbacks entirely, and the server will call us later to break * them */ afs_fs_give_up_callbacks(server, &afs_async_call); } /* * flush the outstanding callback breaks on a server */ void afs_flush_callback_breaks(struct afs_server *server) { cancel_delayed_work(&server->cb_break_work); queue_delayed_work(afs_callback_update_worker, &server->cb_break_work, 0); } #if 0 /* * update a bunch of callbacks */ static void afs_callback_updater(struct work_struct *work) { struct afs_server *server; struct afs_vnode *vnode, *xvnode; time_t now; long timeout; int ret; server = container_of(work, struct afs_server, updater); _enter(""); now = get_seconds(); /* find the first vnode to update */ spin_lock(&server->cb_lock); for (;;) { if (RB_EMPTY_ROOT(&server->cb_promises)) { spin_unlock(&server->cb_lock); _leave(" [nothing]"); return; } vnode = rb_entry(rb_first(&server->cb_promises), struct afs_vnode, cb_promise); if (atomic_read(&vnode->usage) > 0) break; rb_erase(&vnode->cb_promise, &server->cb_promises); vnode->cb_promised = false; } timeout = vnode->update_at - now; if (timeout > 0) { queue_delayed_work(afs_vnode_update_worker, &afs_vnode_update, timeout * HZ); spin_unlock(&server->cb_lock); _leave(" [nothing]"); return; } list_del_init(&vnode->update); atomic_inc(&vnode->usage); spin_unlock(&server->cb_lock); /* we can now perform the update */ _debug("update %s", vnode->vldb.name); vnode->state = AFS_VL_UPDATING; vnode->upd_rej_cnt = 0; vnode->upd_busy_cnt = 0; ret = afs_vnode_update_record(vl, &vldb); switch (ret) { case 0: afs_vnode_apply_update(vl, &vldb); vnode->state = AFS_VL_UPDATING; break; case -ENOMEDIUM: vnode->state = AFS_VL_VOLUME_DELETED; break; default: vnode->state = AFS_VL_UNCERTAIN; break; } /* and then reschedule */ _debug("reschedule"); vnode->update_at = get_seconds() + afs_vnode_update_timeout; spin_lock(&server->cb_lock); if (!list_empty(&server->cb_promises)) { /* next update in 10 minutes, but wait at least 1 second more * than the newest record already queued so that we don't spam * the VL server suddenly with lots of requests */ xvnode = list_entry(server->cb_promises.prev, struct afs_vnode, update); if (vnode->update_at <= xvnode->update_at) vnode->update_at = xvnode->update_at + 1; xvnode = list_entry(server->cb_promises.next, struct afs_vnode, update); timeout = xvnode->update_at - now; if (timeout < 0) timeout = 0; } else { timeout = afs_vnode_update_timeout; } list_add_tail(&vnode->update, &server->cb_promises); _debug("timeout %ld", timeout); queue_delayed_work(afs_vnode_update_worker, &afs_vnode_update, timeout * HZ); spin_unlock(&server->cb_lock); afs_put_vnode(vl); } #endif /* * initialise the callback update process */ int __init afs_callback_update_init(void) { afs_callback_update_worker = create_singlethread_workqueue("kafs_callbackd"); return afs_callback_update_worker ? 0 : -ENOMEM; } /* * shut down the callback update process */ void afs_callback_update_kill(void) { destroy_workqueue(afs_callback_update_worker); }