[linux-2.6-block.git] / fs / afs / callback.c

/*
 * 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);

		spin_lock(&vnode->lock);

		_debug("break callback");

		if (list_empty(&vnode->granted_locks) &&
		    !list_empty(&vnode->pending_locks))
			afs_lock_may_be_available(vnode);
		spin_unlock(&vnode->lock);
	}

	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_break_lock);
			volume->cb_v_break++;
			write_unlock(&volume->cb_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;
	}
}
Commit	Line	Data
1da177e4	1	/*
08e0e7c8	2	* Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
1da177e4 LT	3	*
	4	* This software may be freely redistributed under the terms of the
	5	* GNU General Public License.
	6	*
	7	* You should have received a copy of the GNU General Public License
	8	* along with this program; if not, write to the Free Software
	9	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	10	*
44d1b980	11	* Authors: David Woodhouse <dwmw2@infradead.org>
1da177e4 LT	12	* David Howells <dhowells@redhat.com>
	13	*
	14	*/
	15
	16	#include <linux/kernel.h>
	17	#include <linux/module.h>
	18	#include <linux/init.h>
08e0e7c8	19	#include <linux/circ_buf.h>
e8edc6e0	20	#include <linux/sched.h>
1da177e4	21	#include "internal.h"
08e0e7c8	22
47ea0f2e DH	23	/*
	24	* Create volume and callback interests on a server.
	25	*/
	26	static struct afs_cb_interest afs_create_interest(struct afs_server server,
	27	struct afs_vnode *vnode)
	28	{
	29	struct afs_vol_interest new_vi, vi;
	30	struct afs_cb_interest *new;
	31	struct hlist_node **pp;
	32
	33	new_vi = kzalloc(sizeof(struct afs_vol_interest), GFP_KERNEL);
	34	if (!new_vi)
	35	return NULL;
	36
	37	new = kzalloc(sizeof(struct afs_cb_interest), GFP_KERNEL);
	38	if (!new) {
	39	kfree(new_vi);
	40	return NULL;
	41	}
	42
	43	new_vi->usage = 1;
	44	new_vi->vid = vnode->volume->vid;
	45	INIT_HLIST_NODE(&new_vi->srv_link);
	46	INIT_HLIST_HEAD(&new_vi->cb_interests);
	47
	48	refcount_set(&new->usage, 1);
	49	new->sb = vnode->vfs_inode.i_sb;
	50	new->vid = vnode->volume->vid;
	51	new->server = afs_get_server(server);
	52	INIT_HLIST_NODE(&new->cb_vlink);
	53
	54	write_lock(&server->cb_break_lock);
	55
	56	for (pp = &server->cb_volumes.first; pp; pp = &(pp)->next) {
	57	vi = hlist_entry(*pp, struct afs_vol_interest, srv_link);
	58	if (vi->vid < new_vi->vid)
	59	continue;
	60	if (vi->vid > new_vi->vid)
	61	break;
	62	vi->usage++;
	63	goto found_vi;
	64	}
	65
	66	new_vi->srv_link.pprev = pp;
	67	new_vi->srv_link.next = *pp;
	68	if (*pp)
	69	(*pp)->pprev = &new_vi->srv_link.next;
	70	*pp = &new_vi->srv_link;
	71	vi = new_vi;
	72	new_vi = NULL;
	73	found_vi:
	74
	75	new->vol_interest = vi;
	76	hlist_add_head(&new->cb_vlink, &vi->cb_interests);
	77
	78	write_unlock(&server->cb_break_lock);
	79	kfree(new_vi);
	80	return new;
	81	}
	82
1da177e4	83	/*
c435ee34 DH	84	* Set up an interest-in-callbacks record for a volume on a server and
c435ee34 DH	85	* register it with the server.
d4a96bec	86	* - Called with vnode->io_lock held.
1da177e4	87	*/
c435ee34	88	int afs_register_server_cb_interest(struct afs_vnode *vnode,
d4a96bec DH	89	struct afs_server_list *slist,
d4a96bec DH	90	unsigned int index)
1da177e4	91	{
d4a96bec DH	92	struct afs_server_entry *entry = &slist->servers[index];
d4a96bec DH	93	struct afs_cb_interest cbi, vcbi, new, old;
d2ddc776	94	struct afs_server *server = entry->server;
c435ee34 DH	95
c435ee34 DH	96	again:
d4a96bec DH	97	if (vnode->cb_interest &&
	98	likely(vnode->cb_interest == entry->cb_interest))
	99	return 0;
	100
	101	read_lock(&slist->lock);
	102	cbi = afs_get_cb_interest(entry->cb_interest);
	103	read_unlock(&slist->lock);
	104
c435ee34 DH	105	vcbi = vnode->cb_interest;
c435ee34 DH	106	if (vcbi) {
d4a96bec DH	107	if (vcbi == cbi) {
d4a96bec DH	108	afs_put_cb_interest(afs_v2net(vnode), cbi);
c435ee34	109	return 0;
d4a96bec	110	}
c435ee34	111
d4a96bec DH	112	/* Use a new interest in the server list for the same server
	113	* rather than an old one that's still attached to a vnode.
	114	*/
c435ee34 DH	115	if (cbi && vcbi->server == cbi->server) {
c435ee34 DH	116	write_seqlock(&vnode->cb_lock);
d4a96bec DH	117	old = vnode->cb_interest;
d4a96bec DH	118	vnode->cb_interest = cbi;
c435ee34	119	write_sequnlock(&vnode->cb_lock);
d4a96bec	120	afs_put_cb_interest(afs_v2net(vnode), old);
c435ee34 DH	121	return 0;
c435ee34 DH	122	}
1da177e4	123
d4a96bec	124	/* Re-use the one attached to the vnode. */
c435ee34	125	if (!cbi && vcbi->server == server) {
d4a96bec DH	126	write_lock(&slist->lock);
	127	if (entry->cb_interest) {
	128	write_unlock(&slist->lock);
	129	afs_put_cb_interest(afs_v2net(vnode), cbi);
c435ee34 DH	130	goto again;
c435ee34 DH	131	}
d4a96bec DH	132
	133	entry->cb_interest = cbi;
	134	write_unlock(&slist->lock);
c435ee34 DH	135	return 0;
	136	}
	137	}
1da177e4	138
c435ee34	139	if (!cbi) {
47ea0f2e	140	new = afs_create_interest(server, vnode);
c435ee34 DH	141	if (!new)
	142	return -ENOMEM;
	143
d4a96bec DH	144	write_lock(&slist->lock);
	145	if (!entry->cb_interest) {
	146	entry->cb_interest = afs_get_cb_interest(new);
c435ee34	147	cbi = new;
d4a96bec	148	new = NULL;
c435ee34	149	} else {
d4a96bec	150	cbi = afs_get_cb_interest(entry->cb_interest);
c435ee34	151	}
d4a96bec DH	152	write_unlock(&slist->lock);
d4a96bec DH	153	afs_put_cb_interest(afs_v2net(vnode), new);
08e0e7c8	154	}
1da177e4	155
c435ee34 DH	156	ASSERT(cbi);
	157
	158	/* Change the server the vnode is using. This entails scrubbing any
	159	* interest the vnode had in the previous server it was using.
	160	*/
	161	write_seqlock(&vnode->cb_lock);
	162
d4a96bec DH	163	old = vnode->cb_interest;
d4a96bec DH	164	vnode->cb_interest = cbi;
c435ee34	165	vnode->cb_s_break = cbi->server->cb_s_break;
68251f0a	166	vnode->cb_v_break = vnode->volume->cb_v_break;
c435ee34 DH	167	clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
	168
	169	write_sequnlock(&vnode->cb_lock);
d4a96bec	170	afs_put_cb_interest(afs_v2net(vnode), old);
c435ee34	171	return 0;
08e0e7c8	172	}
1da177e4	173
c435ee34 DH	174	/*
	175	* Remove an interest on a server.
	176	*/
	177	void afs_put_cb_interest(struct afs_net net, struct afs_cb_interest cbi)
	178	{
47ea0f2e DH	179	struct afs_vol_interest *vi;
47ea0f2e DH	180
c435ee34	181	if (cbi && refcount_dec_and_test(&cbi->usage)) {
47ea0f2e	182	if (!hlist_unhashed(&cbi->cb_vlink)) {
c435ee34	183	write_lock(&cbi->server->cb_break_lock);
47ea0f2e DH	184
	185	hlist_del_init(&cbi->cb_vlink);
	186	vi = cbi->vol_interest;
	187	cbi->vol_interest = NULL;
	188	if (--vi->usage == 0)
	189	hlist_del(&vi->srv_link);
	190	else
	191	vi = NULL;
	192
c435ee34	193	write_unlock(&cbi->server->cb_break_lock);
47ea0f2e	194	kfree(vi);
c435ee34 DH	195	afs_put_server(net, cbi->server);
	196	}
	197	kfree(cbi);
08e0e7c8	198	}
c435ee34 DH	199	}
	200
	201	/*
	202	* allow the fileserver to request callback state (re-)initialisation
	203	*/
	204	void afs_init_callback_state(struct afs_server *server)
	205	{
d2ddc776	206	if (!test_and_clear_bit(AFS_SERVER_FL_NEW, &server->flags))
c435ee34	207	server->cb_s_break++;
08e0e7c8 DH	208	}
	209
	210	/*
	211	* actually break a callback
	212	*/
c435ee34	213	void afs_break_callback(struct afs_vnode *vnode)
08e0e7c8 DH	214	{
	215	_enter("");
	216
c435ee34 DH	217	write_seqlock(&vnode->cb_lock);
c435ee34 DH	218
5a813276	219	clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
c435ee34 DH	220	if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
	221	vnode->cb_break++;
	222	afs_clear_permits(vnode);
08e0e7c8	223
08e0e7c8 DH	224	spin_lock(&vnode->lock);
	225
	226	_debug("break callback");
	227
e8d6c554 DH	228	if (list_empty(&vnode->granted_locks) &&
	229	!list_empty(&vnode->pending_locks))
	230	afs_lock_may_be_available(vnode);
08e0e7c8 DH	231	spin_unlock(&vnode->lock);
08e0e7c8 DH	232	}
c435ee34 DH	233
c435ee34 DH	234	write_sequnlock(&vnode->cb_lock);
08e0e7c8 DH	235	}
	236
	237	/*
	238	* allow the fileserver to explicitly break one callback
	239	* - happens when
	240	* - the backing file is changed
	241	* - a lock is released
	242	*/
	243	static void afs_break_one_callback(struct afs_server *server,
	244	struct afs_fid *fid)
	245	{
47ea0f2e	246	struct afs_vol_interest *vi;
c435ee34 DH	247	struct afs_cb_interest *cbi;
c435ee34 DH	248	struct afs_iget_data data;
08e0e7c8	249	struct afs_vnode *vnode;
c435ee34	250	struct inode *inode;
08e0e7c8	251
c435ee34	252	read_lock(&server->cb_break_lock);
47ea0f2e DH	253	hlist_for_each_entry(vi, &server->cb_volumes, srv_link) {
	254	if (vi->vid < fid->vid)
	255	continue;
	256	if (vi->vid > fid->vid) {
	257	vi = NULL;
	258	break;
	259	}
	260	//atomic_inc(&vi->usage);
	261	break;
	262	}
	263
	264	/* TODO: Find all matching volumes if we couldn't match the server and
	265	* break them anyway.
	266	*/
	267	if (!vi)
	268	goto out;
08e0e7c8	269
c435ee34 DH	270	/* Step through all interested superblocks. There may be more than one
	271	* because of cell aliasing.
	272	*/
47ea0f2e	273	hlist_for_each_entry(cbi, &vi->cb_interests, cb_vlink) {
68251f0a DH	274	if (fid->vnode == 0 && fid->unique == 0) {
	275	/* The callback break applies to an entire volume. */
	276	struct afs_super_info *as = AFS_FS_S(cbi->sb);
	277	struct afs_volume *volume = as->volume;
	278
	279	write_lock(&volume->cb_break_lock);
	280	volume->cb_v_break++;
	281	write_unlock(&volume->cb_break_lock);
	282	} else {
	283	data.volume = NULL;
	284	data.fid = *fid;
	285	inode = ilookup5_nowait(cbi->sb, fid->vnode,
	286	afs_iget5_test, &data);
	287	if (inode) {
	288	vnode = AFS_FS_I(inode);
	289	afs_break_callback(vnode);
	290	iput(inode);
	291	}
c435ee34 DH	292	}
c435ee34 DH	293	}
08e0e7c8	294
47ea0f2e	295	out:
c435ee34	296	read_unlock(&server->cb_break_lock);
ec26815a	297	}
1da177e4	298
1da177e4 LT	299	/*
	300	* allow the fileserver to break callback promises
	301	*/
08e0e7c8	302	void afs_break_callbacks(struct afs_server *server, size_t count,
5cf9dd55	303	struct afs_callback_break *callbacks)
1da177e4	304	{
08e0e7c8	305	_enter("%p,%zu,", server, count);
1da177e4	306
08e0e7c8 DH	307	ASSERT(server != NULL);
08e0e7c8 DH	308	ASSERTCMP(count, <=, AFSCBMAX);
1da177e4	309
68251f0a DH	310	/* TODO: Sort the callback break list by volume ID */
68251f0a DH	311
08e0e7c8	312	for (; count > 0; callbacks++, count--) {
1da177e4 LT	313	_debug("- Fid { vl=%08x n=%u u=%u } CB { v=%u x=%u t=%u }",
	314	callbacks->fid.vid,
	315	callbacks->fid.vnode,
	316	callbacks->fid.unique,
5cf9dd55 DH	317	callbacks->cb.version,
	318	callbacks->cb.expiry,
	319	callbacks->cb.type
1da177e4	320	);
08e0e7c8 DH	321	afs_break_one_callback(server, &callbacks->fid);
	322	}
	323
	324	_leave("");
	325	return;
	326	}
1da177e4	327
08e0e7c8	328	/*
c435ee34	329	* Clear the callback interests in a server list.
08e0e7c8	330	*/
d2ddc776	331	void afs_clear_callback_interests(struct afs_net net, struct afs_server_list slist)
08e0e7c8	332	{
c435ee34	333	int i;
08e0e7c8	334
d2ddc776 DH	335	for (i = 0; i < slist->nr_servers; i++) {
	336	afs_put_cb_interest(net, slist->servers[i].cb_interest);
	337	slist->servers[i].cb_interest = NULL;
08e0e7c8	338	}
08e0e7c8	339	}