[GitHub/LineageOS/android_kernel_motorola_exynos9610.git] / fs / afs / volume.c

/* AFS volume management
 *
 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/sched.h>
#include "internal.h"

static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };

/*
 * lookup a volume by name
 * - this can be one of the following:
 *	"%[cell:]volume[.]"		R/W volume
 *	"#[cell:]volume[.]"		R/O or R/W volume (rwparent=0),
 *					 or R/W (rwparent=1) volume
 *	"%[cell:]volume.readonly"	R/O volume
 *	"#[cell:]volume.readonly"	R/O volume
 *	"%[cell:]volume.backup"		Backup volume
 *	"#[cell:]volume.backup"		Backup volume
 *
 * The cell name is optional, and defaults to the current cell.
 *
 * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
 * Guide
 * - Rule 1: Explicit type suffix forces access of that type or nothing
 *           (no suffix, then use Rule 2 & 3)
 * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
 *           if not available
 * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
 *           explicitly told otherwise
 */
struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
{
	struct afs_vlocation *vlocation = NULL;
	struct afs_volume *volume = NULL;
	struct afs_server *server = NULL;
	char srvtmask;
	int ret, loop;

	_enter("{%*.*s,%d}",
	       params->volnamesz, params->volnamesz, params->volname, params->rwpath);

	/* lookup the volume location record */
	vlocation = afs_vlocation_lookup(params->cell, params->key,
					 params->volname, params->volnamesz);
	if (IS_ERR(vlocation)) {
		ret = PTR_ERR(vlocation);
		vlocation = NULL;
		goto error;
	}

	/* make the final decision on the type we want */
	ret = -ENOMEDIUM;
	if (params->force && !(vlocation->vldb.vidmask & (1 << params->type)))
		goto error;

	srvtmask = 0;
	for (loop = 0; loop < vlocation->vldb.nservers; loop++)
		srvtmask |= vlocation->vldb.srvtmask[loop];

	if (params->force) {
		if (!(srvtmask & (1 << params->type)))
			goto error;
	} else if (srvtmask & AFS_VOL_VTM_RO) {
		params->type = AFSVL_ROVOL;
	} else if (srvtmask & AFS_VOL_VTM_RW) {
		params->type = AFSVL_RWVOL;
	} else {
		goto error;
	}

	down_write(&params->cell->vl_sem);

	/* is the volume already active? */
	if (vlocation->vols[params->type]) {
		/* yes - re-use it */
		volume = vlocation->vols[params->type];
		afs_get_volume(volume);
		goto success;
	}

	/* create a new volume record */
	_debug("creating new volume record");

	ret = -ENOMEM;
	volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
	if (!volume)
		goto error_up;

	atomic_set(&volume->usage, 1);
	volume->type		= params->type;
	volume->type_force	= params->force;
	volume->cell		= params->cell;
	volume->vid		= vlocation->vldb.vid[params->type];

	init_rwsem(&volume->server_sem);

	/* look up all the applicable server records */
	for (loop = 0; loop < 8; loop++) {
		if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
			server = afs_lookup_server(
			       volume->cell, &vlocation->vldb.servers[loop]);
			if (IS_ERR(server)) {
				ret = PTR_ERR(server);
				goto error_discard;
			}

			volume->servers[volume->nservers] = server;
			volume->nservers++;
		}
	}

	/* attach the cache and volume location */
#ifdef CONFIG_AFS_FSCACHE
	volume->cache = fscache_acquire_cookie(vlocation->cache,
					       &afs_volume_cache_index_def,
					       volume, true);
#endif
	afs_get_vlocation(vlocation);
	volume->vlocation = vlocation;

	vlocation->vols[volume->type] = volume;

success:
	_debug("kAFS selected %s volume %08x",
	       afs_voltypes[volume->type], volume->vid);
	up_write(&params->cell->vl_sem);
	afs_put_vlocation(vlocation);
	_leave(" = %p", volume);
	return volume;

	/* clean up */
error_up:
	up_write(&params->cell->vl_sem);
error:
	afs_put_vlocation(vlocation);
	_leave(" = %d", ret);
	return ERR_PTR(ret);

error_discard:
	up_write(&params->cell->vl_sem);

	for (loop = volume->nservers - 1; loop >= 0; loop--)
		afs_put_server(volume->servers[loop]);

	kfree(volume);
	goto error;
}

/*
 * destroy a volume record
 */
void afs_put_volume(struct afs_volume *volume)
{
	struct afs_vlocation *vlocation;
	int loop;

	if (!volume)
		return;

	_enter("%p", volume);

	ASSERTCMP(atomic_read(&volume->usage), >, 0);

	vlocation = volume->vlocation;

	/* to prevent a race, the decrement and the dequeue must be effectively
	 * atomic */
	down_write(&vlocation->cell->vl_sem);

	if (likely(!atomic_dec_and_test(&volume->usage))) {
		up_write(&vlocation->cell->vl_sem);
		_leave("");
		return;
	}

	vlocation->vols[volume->type] = NULL;

	up_write(&vlocation->cell->vl_sem);

	/* finish cleaning up the volume */
#ifdef CONFIG_AFS_FSCACHE
	fscache_relinquish_cookie(volume->cache, 0);
#endif
	afs_put_vlocation(vlocation);

	for (loop = volume->nservers - 1; loop >= 0; loop--)
		afs_put_server(volume->servers[loop]);

	kfree(volume);

	_leave(" [destroyed]");
}

/*
 * pick a server to use to try accessing this volume
 * - returns with an elevated usage count on the server chosen
 */
struct afs_server *afs_volume_pick_fileserver(struct afs_vnode *vnode)
{
	struct afs_volume *volume = vnode->volume;
	struct afs_server *server;
	int ret, state, loop;

	_enter("%s", volume->vlocation->vldb.name);

	/* stick with the server we're already using if we can */
	if (vnode->server && vnode->server->fs_state == 0) {
		afs_get_server(vnode->server);
		_leave(" = %p [current]", vnode->server);
		return vnode->server;
	}

	down_read(&volume->server_sem);

	/* handle the no-server case */
	if (volume->nservers == 0) {
		ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
		up_read(&volume->server_sem);
		_leave(" = %d [no servers]", ret);
		return ERR_PTR(ret);
	}

	/* basically, just search the list for the first live server and use
	 * that */
	ret = 0;
	for (loop = 0; loop < volume->nservers; loop++) {
		server = volume->servers[loop];
		state = server->fs_state;

		_debug("consider %d [%d]", loop, state);

		switch (state) {
			/* found an apparently healthy server */
		case 0:
			afs_get_server(server);
			up_read(&volume->server_sem);
			_leave(" = %p (picked %08x)",
			       server, ntohl(server->addr.s_addr));
			return server;

		case -ENETUNREACH:
			if (ret == 0)
				ret = state;
			break;

		case -EHOSTUNREACH:
			if (ret == 0 ||
			    ret == -ENETUNREACH)
				ret = state;
			break;

		case -ECONNREFUSED:
			if (ret == 0 ||
			    ret == -ENETUNREACH ||
			    ret == -EHOSTUNREACH)
				ret = state;
			break;

		default:
		case -EREMOTEIO:
			if (ret == 0 ||
			    ret == -ENETUNREACH ||
			    ret == -EHOSTUNREACH ||
			    ret == -ECONNREFUSED)
				ret = state;
			break;
		}
	}

	/* no available servers
	 * - TODO: handle the no active servers case better
	 */
	up_read(&volume->server_sem);
	_leave(" = %d", ret);
	return ERR_PTR(ret);
}

/*
 * release a server after use
 * - releases the ref on the server struct that was acquired by picking
 * - records result of using a particular server to access a volume
 * - return 0 to try again, 1 if okay or to issue error
 * - the caller must release the server struct if result was 0
 */
int afs_volume_release_fileserver(struct afs_vnode *vnode,
				  struct afs_server *server,
				  int result)
{
	struct afs_volume *volume = vnode->volume;
	unsigned loop;

	_enter("%s,%08x,%d",
	       volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
	       result);

	switch (result) {
		/* success */
	case 0:
		server->fs_act_jif = jiffies;
		server->fs_state = 0;
		_leave("");
		return 1;

		/* the fileserver denied all knowledge of the volume */
	case -ENOMEDIUM:
		server->fs_act_jif = jiffies;
		down_write(&volume->server_sem);

		/* firstly, find where the server is in the active list (if it
		 * is) */
		for (loop = 0; loop < volume->nservers; loop++)
			if (volume->servers[loop] == server)
				goto present;

		/* no longer there - may have been discarded by another op */
		goto try_next_server_upw;

	present:
		volume->nservers--;
		memmove(&volume->servers[loop],
			&volume->servers[loop + 1],
			sizeof(volume->servers[loop]) *
			(volume->nservers - loop));
		volume->servers[volume->nservers] = NULL;
		afs_put_server(server);
		volume->rjservers++;

		if (volume->nservers > 0)
			/* another server might acknowledge its existence */
			goto try_next_server_upw;

		/* handle the case where all the fileservers have rejected the
		 * volume
		 * - TODO: try asking the fileservers for volume information
		 * - TODO: contact the VL server again to see if the volume is
		 *         no longer registered
		 */
		up_write(&volume->server_sem);
		afs_put_server(server);
		_leave(" [completely rejected]");
		return 1;

		/* problem reaching the server */
	case -ENETUNREACH:
	case -EHOSTUNREACH:
	case -ECONNREFUSED:
	case -ETIME:
	case -ETIMEDOUT:
	case -EREMOTEIO:
		/* mark the server as dead
		 * TODO: vary dead timeout depending on error
		 */
		spin_lock(&server->fs_lock);
		if (!server->fs_state) {
			server->fs_dead_jif = jiffies + HZ * 10;
			server->fs_state = result;
			printk("kAFS: SERVER DEAD state=%d\n", result);
		}
		spin_unlock(&server->fs_lock);
		goto try_next_server;

		/* miscellaneous error */
	default:
		server->fs_act_jif = jiffies;
	case -ENOMEM:
	case -ENONET:
		/* tell the caller to accept the result */
		afs_put_server(server);
		_leave(" [local failure]");
		return 1;
	}

	/* tell the caller to loop around and try the next server */
try_next_server_upw:
	up_write(&volume->server_sem);
try_next_server:
	afs_put_server(server);
	_leave(" [try next server]");
	return 0;
}
Commit	Line	Data
	1	/* AFS volume management
	2	*
	3	* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/kernel.h>
	13	#include <linux/module.h>
	14	#include <linux/init.h>
	15	#include <linux/slab.h>
	16	#include <linux/fs.h>
	17	#include <linux/pagemap.h>
	18	#include <linux/sched.h>
	19	#include "internal.h"
	20
	21	static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
	22
	23	/*
	24	* lookup a volume by name
	25	* - this can be one of the following:
	26	* "%[cell:]volume[.]" R/W volume
	27	* "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
	28	* or R/W (rwparent=1) volume
	29	* "%[cell:]volume.readonly" R/O volume
	30	* "#[cell:]volume.readonly" R/O volume
	31	* "%[cell:]volume.backup" Backup volume
	32	* "#[cell:]volume.backup" Backup volume
	33	*
	34	* The cell name is optional, and defaults to the current cell.
	35	*
	36	* See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
	37	* Guide
	38	* - Rule 1: Explicit type suffix forces access of that type or nothing
	39	* (no suffix, then use Rule 2 & 3)
	40	* - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
	41	* if not available
	42	* - Rule 3: If parent volume is R/W, then only mount R/W volume unless
	43	* explicitly told otherwise
	44	*/
	45	struct afs_volume afs_volume_lookup(struct afs_mount_params params)
	46	{
	47	struct afs_vlocation *vlocation = NULL;
	48	struct afs_volume *volume = NULL;
	49	struct afs_server *server = NULL;
	50	char srvtmask;
	51	int ret, loop;
	52
	53	_enter("{%.s,%d}",
	54	params->volnamesz, params->volnamesz, params->volname, params->rwpath);
	55
	56	/* lookup the volume location record */
	57	vlocation = afs_vlocation_lookup(params->cell, params->key,
	58	params->volname, params->volnamesz);
	59	if (IS_ERR(vlocation)) {
	60	ret = PTR_ERR(vlocation);
	61	vlocation = NULL;
	62	goto error;
	63	}
	64
	65	/* make the final decision on the type we want */
	66	ret = -ENOMEDIUM;
	67	if (params->force && !(vlocation->vldb.vidmask & (1 << params->type)))
	68	goto error;
	69
	70	srvtmask = 0;
	71	for (loop = 0; loop < vlocation->vldb.nservers; loop++)
	72	srvtmask \|= vlocation->vldb.srvtmask[loop];
	73
	74	if (params->force) {
	75	if (!(srvtmask & (1 << params->type)))
	76	goto error;
	77	} else if (srvtmask & AFS_VOL_VTM_RO) {
	78	params->type = AFSVL_ROVOL;
	79	} else if (srvtmask & AFS_VOL_VTM_RW) {
	80	params->type = AFSVL_RWVOL;
	81	} else {
	82	goto error;
	83	}
	84
	85	down_write(&params->cell->vl_sem);
	86
	87	/* is the volume already active? */
	88	if (vlocation->vols[params->type]) {
	89	/* yes - re-use it */
	90	volume = vlocation->vols[params->type];
	91	afs_get_volume(volume);
	92	goto success;
	93	}
	94
	95	/* create a new volume record */
	96	_debug("creating new volume record");
	97
	98	ret = -ENOMEM;
	99	volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
	100	if (!volume)
	101	goto error_up;
	102
	103	atomic_set(&volume->usage, 1);
	104	volume->type = params->type;
	105	volume->type_force = params->force;
	106	volume->cell = params->cell;
	107	volume->vid = vlocation->vldb.vid[params->type];
	108
	109	init_rwsem(&volume->server_sem);
	110
	111	/* look up all the applicable server records */
	112	for (loop = 0; loop < 8; loop++) {
	113	if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
	114	server = afs_lookup_server(
	115	volume->cell, &vlocation->vldb.servers[loop]);
	116	if (IS_ERR(server)) {
	117	ret = PTR_ERR(server);
	118	goto error_discard;
	119	}
	120
	121	volume->servers[volume->nservers] = server;
	122	volume->nservers++;
	123	}
	124	}
	125
	126	/* attach the cache and volume location */
	127	#ifdef CONFIG_AFS_FSCACHE
	128	volume->cache = fscache_acquire_cookie(vlocation->cache,
	129	&afs_volume_cache_index_def,
	130	volume, true);
	131	#endif
	132	afs_get_vlocation(vlocation);
	133	volume->vlocation = vlocation;
	134
	135	vlocation->vols[volume->type] = volume;
	136
	137	success:
	138	_debug("kAFS selected %s volume %08x",
	139	afs_voltypes[volume->type], volume->vid);
	140	up_write(&params->cell->vl_sem);
	141	afs_put_vlocation(vlocation);
	142	_leave(" = %p", volume);
	143	return volume;
	144
	145	/* clean up */
	146	error_up:
	147	up_write(&params->cell->vl_sem);
	148	error:
	149	afs_put_vlocation(vlocation);
	150	_leave(" = %d", ret);
	151	return ERR_PTR(ret);
	152
	153	error_discard:
	154	up_write(&params->cell->vl_sem);
	155
	156	for (loop = volume->nservers - 1; loop >= 0; loop--)
	157	afs_put_server(volume->servers[loop]);
	158
	159	kfree(volume);
	160	goto error;
	161	}
	162
	163	/*
	164	* destroy a volume record
	165	*/
	166	void afs_put_volume(struct afs_volume *volume)
	167	{
	168	struct afs_vlocation *vlocation;
	169	int loop;
	170
	171	if (!volume)
	172	return;
	173
	174	_enter("%p", volume);
	175
	176	ASSERTCMP(atomic_read(&volume->usage), >, 0);
	177
	178	vlocation = volume->vlocation;
	179
	180	/* to prevent a race, the decrement and the dequeue must be effectively
	181	* atomic */
	182	down_write(&vlocation->cell->vl_sem);
	183
	184	if (likely(!atomic_dec_and_test(&volume->usage))) {
	185	up_write(&vlocation->cell->vl_sem);
	186	_leave("");
	187	return;
	188	}
	189
	190	vlocation->vols[volume->type] = NULL;
	191
	192	up_write(&vlocation->cell->vl_sem);
	193
	194	/* finish cleaning up the volume */
	195	#ifdef CONFIG_AFS_FSCACHE
	196	fscache_relinquish_cookie(volume->cache, 0);
	197	#endif
	198	afs_put_vlocation(vlocation);
	199
	200	for (loop = volume->nservers - 1; loop >= 0; loop--)
	201	afs_put_server(volume->servers[loop]);
	202
	203	kfree(volume);
	204
	205	_leave(" [destroyed]");
	206	}
	207
	208	/*
	209	* pick a server to use to try accessing this volume
	210	* - returns with an elevated usage count on the server chosen
	211	*/
	212	struct afs_server afs_volume_pick_fileserver(struct afs_vnode vnode)
	213	{
	214	struct afs_volume *volume = vnode->volume;
	215	struct afs_server *server;
	216	int ret, state, loop;
	217
	218	_enter("%s", volume->vlocation->vldb.name);
	219
	220	/* stick with the server we're already using if we can */
	221	if (vnode->server && vnode->server->fs_state == 0) {
	222	afs_get_server(vnode->server);
	223	_leave(" = %p [current]", vnode->server);
	224	return vnode->server;
	225	}
	226
	227	down_read(&volume->server_sem);
	228
	229	/* handle the no-server case */
	230	if (volume->nservers == 0) {
	231	ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
	232	up_read(&volume->server_sem);
	233	_leave(" = %d [no servers]", ret);
	234	return ERR_PTR(ret);
	235	}
	236
	237	/* basically, just search the list for the first live server and use
	238	* that */
	239	ret = 0;
	240	for (loop = 0; loop < volume->nservers; loop++) {
	241	server = volume->servers[loop];
	242	state = server->fs_state;
	243
	244	_debug("consider %d [%d]", loop, state);
	245
	246	switch (state) {
	247	/* found an apparently healthy server */
	248	case 0:
	249	afs_get_server(server);
	250	up_read(&volume->server_sem);
	251	_leave(" = %p (picked %08x)",
	252	server, ntohl(server->addr.s_addr));
	253	return server;
	254
	255	case -ENETUNREACH:
	256	if (ret == 0)
	257	ret = state;
	258	break;
	259
	260	case -EHOSTUNREACH:
	261	if (ret == 0 \|\|
	262	ret == -ENETUNREACH)
	263	ret = state;
	264	break;
	265
	266	case -ECONNREFUSED:
	267	if (ret == 0 \|\|
	268	ret == -ENETUNREACH \|\|
	269	ret == -EHOSTUNREACH)
	270	ret = state;
	271	break;
	272
	273	default:
	274	case -EREMOTEIO:
	275	if (ret == 0 \|\|
	276	ret == -ENETUNREACH \|\|
	277	ret == -EHOSTUNREACH \|\|
	278	ret == -ECONNREFUSED)
	279	ret = state;
	280	break;
	281	}
	282	}
	283
	284	/* no available servers
	285	* - TODO: handle the no active servers case better
	286	*/
	287	up_read(&volume->server_sem);
	288	_leave(" = %d", ret);
	289	return ERR_PTR(ret);
	290	}
	291
	292	/*
	293	* release a server after use
	294	* - releases the ref on the server struct that was acquired by picking
	295	* - records result of using a particular server to access a volume
	296	* - return 0 to try again, 1 if okay or to issue error
	297	* - the caller must release the server struct if result was 0
	298	*/
	299	int afs_volume_release_fileserver(struct afs_vnode *vnode,
	300	struct afs_server *server,
	301	int result)
	302	{
	303	struct afs_volume *volume = vnode->volume;
	304	unsigned loop;
	305
	306	_enter("%s,%08x,%d",
	307	volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
	308	result);
	309
	310	switch (result) {
	311	/* success */
	312	case 0:
	313	server->fs_act_jif = jiffies;
	314	server->fs_state = 0;
	315	_leave("");
	316	return 1;
	317
	318	/* the fileserver denied all knowledge of the volume */
	319	case -ENOMEDIUM:
	320	server->fs_act_jif = jiffies;
	321	down_write(&volume->server_sem);
	322
	323	/* firstly, find where the server is in the active list (if it
	324	* is) */
	325	for (loop = 0; loop < volume->nservers; loop++)
	326	if (volume->servers[loop] == server)
	327	goto present;
	328
	329	/* no longer there - may have been discarded by another op */
	330	goto try_next_server_upw;
	331
	332	present:
	333	volume->nservers--;
	334	memmove(&volume->servers[loop],
	335	&volume->servers[loop + 1],
	336	sizeof(volume->servers[loop]) *
	337	(volume->nservers - loop));
	338	volume->servers[volume->nservers] = NULL;
	339	afs_put_server(server);
	340	volume->rjservers++;
	341
	342	if (volume->nservers > 0)
	343	/* another server might acknowledge its existence */
	344	goto try_next_server_upw;
	345
	346	/* handle the case where all the fileservers have rejected the
	347	* volume
	348	* - TODO: try asking the fileservers for volume information
	349	* - TODO: contact the VL server again to see if the volume is
	350	* no longer registered
	351	*/
	352	up_write(&volume->server_sem);
	353	afs_put_server(server);
	354	_leave(" [completely rejected]");
	355	return 1;
	356
	357	/* problem reaching the server */
	358	case -ENETUNREACH:
	359	case -EHOSTUNREACH:
	360	case -ECONNREFUSED:
	361	case -ETIME:
	362	case -ETIMEDOUT:
	363	case -EREMOTEIO:
	364	/* mark the server as dead
	365	* TODO: vary dead timeout depending on error
	366	*/
	367	spin_lock(&server->fs_lock);
	368	if (!server->fs_state) {
	369	server->fs_dead_jif = jiffies + HZ * 10;
	370	server->fs_state = result;
	371	printk("kAFS: SERVER DEAD state=%d\n", result);
	372	}
	373	spin_unlock(&server->fs_lock);
	374	goto try_next_server;
	375
	376	/* miscellaneous error */
	377	default:
	378	server->fs_act_jif = jiffies;
	379	case -ENOMEM:
	380	case -ENONET:
	381	/* tell the caller to accept the result */
	382	afs_put_server(server);
	383	_leave(" [local failure]");
	384	return 1;
	385	}
	386
	387	/* tell the caller to loop around and try the next server */
	388	try_next_server_upw:
	389	up_write(&volume->server_sem);
	390	try_next_server:
	391	afs_put_server(server);
	392	_leave(" [try next server]");
	393	return 0;
	394	}