fs/afs/callback.c - linux - Git at Google

 /*
  * 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, afs_server_trace_get_new_cbi);
 	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:
 	vcbi = rcu_dereference_protected(vnode->cb_interest,
 					 lockdep_is_held(&vnode->io_lock));
 	if (vcbi && likely(vcbi == entry->cb_interest))
 		return 0;

 	read_lock(&slist->lock);
 	cbi = afs_get_cb_interest(entry->cb_interest);
 	read_unlock(&slist->lock);

 	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 = rcu_dereference_protected(vnode->cb_interest,
 							lockdep_is_held(&vnode->cb_lock.lock));
 			rcu_assign_pointer(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 = rcu_dereference_protected(vnode->cb_interest,
 					lockdep_is_held(&vnode->cb_lock.lock));
 	rcu_assign_pointer(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);
 			if (vi)
 				kfree_rcu(vi, rcu);
 			afs_put_server(net, cbi->server, afs_server_trace_put_cbi);
 		}
 		kfree_rcu(cbi, rcu);
 	}
 }

 /*
  * allow the fileserver to request callback state (re-)initialisation
  */
 void afs_init_callback_state(struct afs_server *server)
 {
 	server->cb_s_break++;
 }

 /*
  * 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);
 }

 /*
  * 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++;
 			trace_afs_cb_break(fid, volume->cb_v_break,
 					   afs_cb_break_for_volume_callback, false);
 			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, afs_cb_break_for_callback);
 				iput(inode);
 			} else {
 				trace_afs_cb_miss(fid, afs_cb_break_for_callback);
 			}
 		}
 	}

 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);

 	/* TODO: Sort the callback break list by volume ID */

 	for (; count > 0; callbacks++, count--) {
 		_debug("- Fid { vl=%08llx n=%llu u=%u }",
 		       callbacks->fid.vid,
 		       callbacks->fid.vnode,
 		       callbacks->fid.unique);
 		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;
 	}
 }
	/*
	* 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, afs_server_trace_get_new_cbi);
	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:
	vcbi = rcu_dereference_protected(vnode->cb_interest,
	lockdep_is_held(&vnode->io_lock));
	if (vcbi && likely(vcbi == entry->cb_interest))
	return 0;

	read_lock(&slist->lock);
	cbi = afs_get_cb_interest(entry->cb_interest);
	read_unlock(&slist->lock);

	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 = rcu_dereference_protected(vnode->cb_interest,
	lockdep_is_held(&vnode->cb_lock.lock));
	rcu_assign_pointer(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 = rcu_dereference_protected(vnode->cb_interest,
	lockdep_is_held(&vnode->cb_lock.lock));
	rcu_assign_pointer(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);
	if (vi)
	kfree_rcu(vi, rcu);
	afs_put_server(net, cbi->server, afs_server_trace_put_cbi);
	}
	kfree_rcu(cbi, rcu);
	}
	}

	/*
	* allow the fileserver to request callback state (re-)initialisation
	*/
	void afs_init_callback_state(struct afs_server *server)
	{
	server->cb_s_break++;
	}

	/*
	* 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);
	}

	/*
	* 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++;
	trace_afs_cb_break(fid, volume->cb_v_break,
	afs_cb_break_for_volume_callback, false);
	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, afs_cb_break_for_callback);
	iput(inode);
	} else {
	trace_afs_cb_miss(fid, afs_cb_break_for_callback);
	}
	}
	}

	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);

	/* TODO: Sort the callback break list by volume ID */

	for (; count > 0; callbacks++, count--) {
	_debug("- Fid { vl=%08llx n=%llu u=%u }",
	callbacks->fid.vid,
	callbacks->fid.vnode,
	callbacks->fid.unique);
	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;
	}
	}