/* * 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" /* * Allow the fileserver to request callback state (re-)initialisation. * Unfortunately, UUIDs are not guaranteed unique. */void afs_init_callback_state(struct afs_server *server){	rcu_read_lock();	do {		server->cb_s_break++;		server = rcu_dereference(server->uuid_next);	} while (0);	rcu_read_unlock();} /* * 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 (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); 		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;	int seq = 0; 	do {		/* Unfortunately, rbtree walking doesn't give reliable results		 * under just the RCU read lock, so we have to check for		 * changes.		 */		read_seqbegin_or_lock(&cell->volume_lock, &seq); 		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;		} 	} while (need_seqretry(&cell->volume_lock, seq)); 	done_seqretry(&cell->volume_lock, seq);	return 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_volume *volume,				   struct afs_fid *fid){	struct super_block *sb;	struct afs_vnode *vnode;	struct inode *inode; 	if (fid->vnode == 0 && fid->unique == 0) {		/* The callback break applies to an entire volume. */		write_lock(&volume->cb_v_break_lock);		volume->cb_v_break++;		trace_afs_cb_break(fid, volume->cb_v_break,				   afs_cb_break_for_volume_callback, false);		write_unlock(&volume->cb_v_break_lock);		return;	} 	/* 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; 	volume = afs_lookup_volume_rcu(server->cell, vid); 	/* 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(volume, &cbb->fid);		} else {			*residue++ = *cbb;		}	}} /* * 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); 	rcu_read_lock(); 	while (count > 0)		afs_break_some_callbacks(server, callbacks, &count); 	rcu_read_unlock();	return;}