1 files changed, 262 insertions, 0 deletions
diff --git a/fs/afs/callback.c b/fs/afs/callback.c
new file mode 100644
index 000000000..61354003c
--- /dev/null
+++ b/fs/afs/callback.c
@@ -0,0 +1,262 @@
+/*
+ * 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"
+
+/*
+ * Handle invalidation of an mmap'd file.  We invalidate all the PTEs referring
+ * to the pages in this file's pagecache, forcing the kernel to go through
+ * ->fault() or ->page_mkwrite() - at which point we can handle invalidation
+ * more fully.
+ */
+void afs_invalidate_mmap_work(struct work_struct *work)
+{
+	struct afs_vnode *vnode = container_of(work, struct afs_vnode, cb_work);
+
+	unmap_mapping_pages(vnode->netfs.inode.i_mapping, 0, 0, false);
+}
+
+static void afs_volume_init_callback(struct afs_volume *volume)
+{
+	struct afs_vnode *vnode;
+
+	down_read(&volume->open_mmaps_lock);
+
+	list_for_each_entry(vnode, &volume->open_mmaps, cb_mmap_link) {
+		if (vnode->cb_v_check != atomic_read(&volume->cb_v_break)) {
+			afs_clear_cb_promise(vnode, afs_cb_promise_clear_vol_init_cb);
+			queue_work(system_dfl_wq, &vnode->cb_work);
+		}
+	}
+
+	up_read(&volume->open_mmaps_lock);
+}
+
+/*
+ * Allow the fileserver to request callback state (re-)initialisation.
+ * Unfortunately, UUIDs are not guaranteed unique.
+ */
+void afs_init_callback_state(struct afs_server *server)
+{
+	struct afs_server_entry *se;
+
+	down_read(&server->cell->vs_lock);
+
+	list_for_each_entry(se, &server->volumes, slink) {
+		se->cb_expires_at = AFS_NO_CB_PROMISE;
+		se->volume->cb_expires_at = AFS_NO_CB_PROMISE;
+		trace_afs_cb_v_break(se->volume->vid, atomic_read(&se->volume->cb_v_break),
+				     afs_cb_break_for_s_reinit);
+		if (!list_empty(&se->volume->open_mmaps))
+			afs_volume_init_callback(se->volume);
+	}
+
+	up_read(&server->cell->vs_lock);
+}
+
+/*
+ * actually break a callback
+ */
+void __afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
+{
+	_enter("");
+
+	clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
+	if (afs_clear_cb_promise(vnode, afs_cb_promise_clear_cb_break)) {
+		vnode->cb_break++;
+		vnode->cb_v_check = atomic_read(&vnode->volume->cb_v_break);
+		afs_clear_permits(vnode);
+
+		if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
+			afs_lock_may_be_available(vnode);
+
+		if (reason != afs_cb_break_for_deleted &&
+		    vnode->status.type == AFS_FTYPE_FILE &&
+		    atomic_read(&vnode->cb_nr_mmap))
+			queue_work(system_dfl_wq, &vnode->cb_work);
+
+		trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, true);
+	} else {
+		trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, false);
+	}
+}
+
+void afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
+{
+	write_seqlock(&vnode->cb_lock);
+	__afs_break_callback(vnode, reason);
+	write_sequnlock(&vnode->cb_lock);
+}
+
+/*
+ * Look up a volume by volume ID under RCU conditions.
+ */
+static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell,
+						afs_volid_t vid)
+{
+	struct afs_volume *volume = NULL;
+	struct rb_node *p;
+
+	scoped_seqlock_read(&cell->volume_lock, ss_lock) {
+		/* Unfortunately, rbtree walking doesn't give reliable results
+		 * under just the RCU read lock, so we have to check for
+		 * changes.
+		 */
+		p = rcu_dereference_raw(cell->volumes.rb_node);
+		while (p) {
+			volume = rb_entry(p, struct afs_volume, cell_node);
+
+			if (volume->vid < vid)
+				p = rcu_dereference_raw(p->rb_left);
+			else if (volume->vid > vid)
+				p = rcu_dereference_raw(p->rb_right);
+			else
+				break;
+			volume = NULL;
+		}
+
+		if (volume && afs_try_get_volume(volume, afs_volume_trace_get_callback))
+			break;
+		volume = NULL;
+	}
+
+	return volume;
+}
+
+/*
+ * Allow the fileserver to break callbacks at the volume-level.  This is
+ * typically done when, for example, a R/W volume is snapshotted to a R/O
+ * volume (the only way to change an R/O volume).  It may also, however, happen
+ * when a volserver takes control of a volume (offlining it, moving it, etc.).
+ *
+ * Every file in that volume will need to be reevaluated.
+ */
+static void afs_break_volume_callback(struct afs_server *server,
+				      struct afs_volume *volume)
+	__releases(RCU)
+{
+	struct afs_server_list *slist = rcu_dereference(volume->servers);
+	unsigned int i, cb_v_break;
+
+	write_lock(&volume->cb_v_break_lock);
+
+	for (i = 0; i < slist->nr_servers; i++)
+		if (slist->servers[i].server == server)
+			slist->servers[i].cb_expires_at = AFS_NO_CB_PROMISE;
+	volume->cb_expires_at = AFS_NO_CB_PROMISE;
+
+	cb_v_break = atomic_inc_return_release(&volume->cb_v_break);
+	trace_afs_cb_v_break(volume->vid, cb_v_break, afs_cb_break_for_volume_callback);
+
+	write_unlock(&volume->cb_v_break_lock);
+	rcu_read_unlock();
+
+	if (!list_empty(&volume->open_mmaps))
+		afs_volume_init_callback(volume);
+}
+
+/*
+ * 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_volume *volume,
+				   struct afs_fid *fid)
+{
+	struct super_block *sb;
+	struct afs_vnode *vnode;
+	struct inode *inode;
+
+	/* See if we can find a matching inode - even an I_NEW inode needs to
+	 * be marked as it can have its callback broken before we finish
+	 * setting up the local inode.
+	 */
+	sb = rcu_dereference(volume->sb);
+	if (!sb)
+		return;
+
+	inode = find_inode_rcu(sb, fid->vnode, afs_ilookup5_test_by_fid, fid);
+	if (inode) {
+		vnode = AFS_FS_I(inode);
+		afs_break_callback(vnode, afs_cb_break_for_callback);
+	} else {
+		trace_afs_cb_miss(fid, afs_cb_break_for_callback);
+	}
+}
+
+static void afs_break_some_callbacks(struct afs_server *server,
+				     struct afs_callback_break *cbb,
+				     size_t *_count)
+{
+	struct afs_callback_break *residue = cbb;
+	struct afs_volume *volume;
+	afs_volid_t vid = cbb->fid.vid;
+	size_t i;
+
+	rcu_read_lock();
+	volume = afs_lookup_volume_rcu(server->cell, vid);
+	if (!volume) {
+		/* Ignore breaks on unknown volumes. */
+		rcu_read_unlock();
+		*_count = 0;
+	} else if (cbb->fid.vnode == 0 && cbb->fid.unique == 0) {
+		afs_break_volume_callback(server, volume);
+		*_count -= 1;
+		if (*_count)
+			memmove(cbb, cbb + 1, sizeof(*cbb) * *_count);
+	} else {
+		/* TODO: Find all matching volumes if we couldn't match the server and
+		 * break them anyway.
+		 */
+
+		for (i = *_count; i > 0; cbb++, i--) {
+			if (cbb->fid.vid == vid) {
+				_debug("- Fid { vl=%08llx n=%llu u=%u }",
+				       cbb->fid.vid,
+				       cbb->fid.vnode,
+				       cbb->fid.unique);
+				--*_count;
+				if (volume)
+					afs_break_one_callback(server, volume, &cbb->fid);
+			} else {
+				*residue++ = *cbb;
+			}
+		}
+		rcu_read_unlock();
+	}
+
+	afs_put_volume(volume, afs_volume_trace_put_callback);
+}
+
+/*
+ * allow the fileserver to break callback promises
+ */
+void afs_break_callbacks(struct afs_server *server, size_t count,
+			 struct afs_callback_break *callbacks)
+{
+	_enter("%p,%zu,", server, count);
+
+	ASSERT(server != NULL);
+
+	while (count > 0)
+		afs_break_some_callbacks(server, callbacks, &count);
+}