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-rw-r--r--fs/afs/callback.c475
1 files changed, 475 insertions, 0 deletions
diff --git a/fs/afs/callback.c b/fs/afs/callback.c
new file mode 100644
index 000000000..7ef637d7f
--- /dev/null
+++ b/fs/afs/callback.c
@@ -0,0 +1,475 @@
+/*
+ * 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)
+{
+ mod_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);
+}
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