1 files changed, 333 insertions, 0 deletions

diff --git a/fs/afs/callback.c b/fs/afs/callback.c
new file mode 100644
index 000000000..97283b04f
--- /dev/null
+++ b/fs/afs/callback.c
@@ -0,0 +1,333 @@
+/*
+ * 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"
+
+/*
+ * Create volume and callback interests on a server.
+ */
+static struct afs_cb_interest *afs_create_interest(struct afs_server *server,
+						   struct afs_vnode *vnode)
+{
+	struct afs_vol_interest *new_vi, *vi;
+	struct afs_cb_interest *new;
+	struct hlist_node **pp;
+
+	new_vi = kzalloc(sizeof(struct afs_vol_interest), GFP_KERNEL);
+	if (!new_vi)
+		return NULL;
+
+	new = kzalloc(sizeof(struct afs_cb_interest), GFP_KERNEL);
+	if (!new) {
+		kfree(new_vi);
+		return NULL;
+	}
+
+	new_vi->usage = 1;
+	new_vi->vid = vnode->volume->vid;
+	INIT_HLIST_NODE(&new_vi->srv_link);
+	INIT_HLIST_HEAD(&new_vi->cb_interests);
+
+	refcount_set(&new->usage, 1);
+	new->sb = vnode->vfs_inode.i_sb;
+	new->vid = vnode->volume->vid;
+	new->server = afs_get_server(server);
+	INIT_HLIST_NODE(&new->cb_vlink);
+
+	write_lock(&server->cb_break_lock);
+
+	for (pp = &server->cb_volumes.first; *pp; pp = &(*pp)->next) {
+		vi = hlist_entry(*pp, struct afs_vol_interest, srv_link);
+		if (vi->vid < new_vi->vid)
+			continue;
+		if (vi->vid > new_vi->vid)
+			break;
+		vi->usage++;
+		goto found_vi;
+	}
+
+	new_vi->srv_link.pprev = pp;
+	new_vi->srv_link.next = *pp;
+	if (*pp)
+		(*pp)->pprev = &new_vi->srv_link.next;
+	*pp = &new_vi->srv_link;
+	vi = new_vi;
+	new_vi = NULL;
+found_vi:
+
+	new->vol_interest = vi;
+	hlist_add_head(&new->cb_vlink, &vi->cb_interests);
+
+	write_unlock(&server->cb_break_lock);
+	kfree(new_vi);
+	return new;
+}
+
+/*
+ * Set up an interest-in-callbacks record for a volume on a server and
+ * register it with the server.
+ * - Called with vnode->io_lock held.
+ */
+int afs_register_server_cb_interest(struct afs_vnode *vnode,
+				    struct afs_server_list *slist,
+				    unsigned int index)
+{
+	struct afs_server_entry *entry = &slist->servers[index];
+	struct afs_cb_interest *cbi, *vcbi, *new, *old;
+	struct afs_server *server = entry->server;
+
+again:
+	if (vnode->cb_interest &&
+	    likely(vnode->cb_interest == entry->cb_interest))
+		return 0;
+
+	read_lock(&slist->lock);
+	cbi = afs_get_cb_interest(entry->cb_interest);
+	read_unlock(&slist->lock);
+
+	vcbi = vnode->cb_interest;
+	if (vcbi) {
+		if (vcbi == cbi) {
+			afs_put_cb_interest(afs_v2net(vnode), cbi);
+			return 0;
+		}
+
+		/* Use a new interest in the server list for the same server
+		 * rather than an old one that's still attached to a vnode.
+		 */
+		if (cbi && vcbi->server == cbi->server) {
+			write_seqlock(&vnode->cb_lock);
+			old = vnode->cb_interest;
+			vnode->cb_interest = cbi;
+			write_sequnlock(&vnode->cb_lock);
+			afs_put_cb_interest(afs_v2net(vnode), old);
+			return 0;
+		}
+
+		/* Re-use the one attached to the vnode. */
+		if (!cbi && vcbi->server == server) {
+			write_lock(&slist->lock);
+			if (entry->cb_interest) {
+				write_unlock(&slist->lock);
+				afs_put_cb_interest(afs_v2net(vnode), cbi);
+				goto again;
+			}
+
+			entry->cb_interest = cbi;
+			write_unlock(&slist->lock);
+			return 0;
+		}
+	}
+
+	if (!cbi) {
+		new = afs_create_interest(server, vnode);
+		if (!new)
+			return -ENOMEM;
+
+		write_lock(&slist->lock);
+		if (!entry->cb_interest) {
+			entry->cb_interest = afs_get_cb_interest(new);
+			cbi = new;
+			new = NULL;
+		} else {
+			cbi = afs_get_cb_interest(entry->cb_interest);
+		}
+		write_unlock(&slist->lock);
+		afs_put_cb_interest(afs_v2net(vnode), new);
+	}
+
+	ASSERT(cbi);
+
+	/* Change the server the vnode is using.  This entails scrubbing any
+	 * interest the vnode had in the previous server it was using.
+	 */
+	write_seqlock(&vnode->cb_lock);
+
+	old = vnode->cb_interest;
+	vnode->cb_interest = cbi;
+	vnode->cb_s_break = cbi->server->cb_s_break;
+	vnode->cb_v_break = vnode->volume->cb_v_break;
+	clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
+
+	write_sequnlock(&vnode->cb_lock);
+	afs_put_cb_interest(afs_v2net(vnode), old);
+	return 0;
+}
+
+/*
+ * Remove an interest on a server.
+ */
+void afs_put_cb_interest(struct afs_net *net, struct afs_cb_interest *cbi)
+{
+	struct afs_vol_interest *vi;
+
+	if (cbi && refcount_dec_and_test(&cbi->usage)) {
+		if (!hlist_unhashed(&cbi->cb_vlink)) {
+			write_lock(&cbi->server->cb_break_lock);
+
+			hlist_del_init(&cbi->cb_vlink);
+			vi = cbi->vol_interest;
+			cbi->vol_interest = NULL;
+			if (--vi->usage == 0)
+				hlist_del(&vi->srv_link);
+			else
+				vi = NULL;
+
+			write_unlock(&cbi->server->cb_break_lock);
+			kfree(vi);
+			afs_put_server(net, cbi->server);
+		}
+		kfree(cbi);
+	}
+}
+
+/*
+ * allow the fileserver to request callback state (re-)initialisation
+ */
+void afs_init_callback_state(struct afs_server *server)
+{
+	if (!test_and_clear_bit(AFS_SERVER_FL_NEW, &server->flags))
+		server->cb_s_break++;
+}
+
+/*
+ * actually break a callback
+ */
+void afs_break_callback(struct afs_vnode *vnode)
+{
+	_enter("");
+
+	write_seqlock(&vnode->cb_lock);
+
+	clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
+	if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
+		vnode->cb_break++;
+		afs_clear_permits(vnode);
+
+		if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
+			afs_lock_may_be_available(vnode);
+	}
+
+	write_sequnlock(&vnode->cb_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_vol_interest *vi;
+	struct afs_cb_interest *cbi;
+	struct afs_iget_data data;
+	struct afs_vnode *vnode;
+	struct inode *inode;
+
+	read_lock(&server->cb_break_lock);
+	hlist_for_each_entry(vi, &server->cb_volumes, srv_link) {
+		if (vi->vid < fid->vid)
+			continue;
+		if (vi->vid > fid->vid) {
+			vi = NULL;
+			break;
+		}
+		//atomic_inc(&vi->usage);
+		break;
+	}
+
+	/* TODO: Find all matching volumes if we couldn't match the server and
+	 * break them anyway.
+	 */
+	if (!vi)
+		goto out;
+
+	/* Step through all interested superblocks.  There may be more than one
+	 * because of cell aliasing.
+	 */
+	hlist_for_each_entry(cbi, &vi->cb_interests, cb_vlink) {
+		if (fid->vnode == 0 && fid->unique == 0) {
+			/* The callback break applies to an entire volume. */
+			struct afs_super_info *as = AFS_FS_S(cbi->sb);
+			struct afs_volume *volume = as->volume;
+
+			write_lock(&volume->cb_v_break_lock);
+			volume->cb_v_break++;
+			write_unlock(&volume->cb_v_break_lock);
+		} else {
+			data.volume = NULL;
+			data.fid = *fid;
+			inode = ilookup5_nowait(cbi->sb, fid->vnode,
+						afs_iget5_test, &data);
+			if (inode) {
+				vnode = AFS_FS_I(inode);
+				afs_break_callback(vnode);
+				iput(inode);
+			}
+		}
+	}
+
+out:
+	read_unlock(&server->cb_break_lock);
+}
+
+/*
+ * 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);
+	ASSERTCMP(count, <=, AFSCBMAX);
+
+	/* TODO: Sort the callback break list by volume ID */
+
+	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->cb.version,
+		       callbacks->cb.expiry,
+		       callbacks->cb.type
+		       );
+		afs_break_one_callback(server, &callbacks->fid);
+	}
+
+	_leave("");
+	return;
+}
+
+/*
+ * Clear the callback interests in a server list.
+ */
+void afs_clear_callback_interests(struct afs_net *net, struct afs_server_list *slist)
+{
+	int i;
+
+	for (i = 0; i < slist->nr_servers; i++) {
+		afs_put_cb_interest(net, slist->servers[i].cb_interest);
+		slist->servers[i].cb_interest = NULL;
+	}
+}