[people/ms/linux.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 "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(const char *name, struct afs_cell *cell,
				     int rwpath)
{
	struct afs_vlocation *vlocation = NULL;
	struct afs_volume *volume = NULL;
	struct afs_server *server = NULL;
	afs_voltype_t type;
	const char *cellname, *volname, *suffix;
	char srvtmask;
	int force, ret, loop, cellnamesz, volnamesz;

	_enter("%s,,%d,", name, rwpath);

	if (!name || (name[0] != '%' && name[0] != '#') || !name[1]) {
		printk("kAFS: unparsable volume name\n");
		return ERR_PTR(-EINVAL);
	}

	/* determine the type of volume we're looking for */
	force = 0;
	type = AFSVL_ROVOL;

	if (rwpath || name[0] == '%') {
		type = AFSVL_RWVOL;
		force = 1;
	}

	suffix = strrchr(name, '.');
	if (suffix) {
		if (strcmp(suffix, ".readonly") == 0) {
			type = AFSVL_ROVOL;
			force = 1;
		} else if (strcmp(suffix, ".backup") == 0) {
			type = AFSVL_BACKVOL;
			force = 1;
		} else if (suffix[1] == 0) {
		} else {
			suffix = NULL;
		}
	}

	/* split the cell and volume names */
	name++;
	volname = strchr(name, ':');
	if (volname) {
		cellname = name;
		cellnamesz = volname - name;
		volname++;
	} else {
		volname = name;
		cellname = NULL;
		cellnamesz = 0;
	}

	volnamesz = suffix ? suffix - volname : strlen(volname);

	_debug("CELL:%*.*s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
	       cellnamesz, cellnamesz, cellname ?: "", cell,
	       volnamesz, volnamesz, volname, suffix ?: "-",
	       type,
	       force ? " FORCE" : "");

	/* lookup the cell record */
	if (cellname || !cell) {
		cell = afs_cell_lookup(cellname, cellnamesz);
		if (IS_ERR(cell)) {
			ret = PTR_ERR(cell);
			printk("kAFS: unable to lookup cell '%s'\n",
			       cellname ?: "");
			goto error;
		}
	} else {
		afs_get_cell(cell);
	}

	/* lookup the volume location record */
	vlocation = afs_vlocation_lookup(cell, volname, 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 (force && !(vlocation->vldb.vidmask & (1 << type)))
		goto error;

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

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

	down_write(&cell->vl_sem);

	/* is the volume already active? */
	if (vlocation->vols[type]) {
		/* yes - re-use it */
		volume = vlocation->vols[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		= type;
	volume->type_force	= force;
	volume->cell		= cell;
	volume->vid		= vlocation->vldb.vid[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 AFS_CACHING_SUPPORT
	cachefs_acquire_cookie(vlocation->cache,
			       &afs_vnode_cache_index_def,
			       volume,
			       &volume->cache);
#endif

	afs_get_vlocation(vlocation);
	volume->vlocation = vlocation;

	vlocation->vols[type] = volume;

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

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

error_discard:
	up_write(&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 AFS_CACHING_SUPPORT
	cachefs_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
 */
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;
		break;

		/* 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:
		break;
	}

	/* tell the caller to accept the result */
	afs_put_server(server);
	_leave("");
	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
ec26815a	1	/* AFS volume management
1da177e4	2	*
08e0e7c8	3	* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
1da177e4 LT	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>
1da177e4 LT	18	#include "internal.h"
1da177e4 LT	19
1da177e4	20	static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
1da177e4	21
1da177e4 LT	22	/*
	23	* lookup a volume by name
	24	* - this can be one of the following:
	25	* "%[cell:]volume[.]" R/W volume
	26	* "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
	27	* or R/W (rwparent=1) volume
	28	* "%[cell:]volume.readonly" R/O volume
	29	* "#[cell:]volume.readonly" R/O volume
	30	* "%[cell:]volume.backup" Backup volume
	31	* "#[cell:]volume.backup" Backup volume
	32	*
	33	* The cell name is optional, and defaults to the current cell.
	34	*
	35	* See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
	36	* Guide
	37	* - Rule 1: Explicit type suffix forces access of that type or nothing
	38	* (no suffix, then use Rule 2 & 3)
	39	* - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
	40	* if not available
	41	* - Rule 3: If parent volume is R/W, then only mount R/W volume unless
	42	* explicitly told otherwise
	43	*/
08e0e7c8 DH	44	struct afs_volume afs_volume_lookup(const char name, struct afs_cell *cell,
08e0e7c8 DH	45	int rwpath)
1da177e4 LT	46	{
	47	struct afs_vlocation *vlocation = NULL;
	48	struct afs_volume *volume = NULL;
08e0e7c8	49	struct afs_server *server = NULL;
1da177e4 LT	50	afs_voltype_t type;
	51	const char cellname, volname, *suffix;
	52	char srvtmask;
	53	int force, ret, loop, cellnamesz, volnamesz;
	54
	55	_enter("%s,,%d,", name, rwpath);
	56
	57	if (!name \|\| (name[0] != '%' && name[0] != '#') \|\| !name[1]) {
	58	printk("kAFS: unparsable volume name\n");
08e0e7c8	59	return ERR_PTR(-EINVAL);
1da177e4 LT	60	}
	61
	62	/* determine the type of volume we're looking for */
	63	force = 0;
	64	type = AFSVL_ROVOL;
	65
	66	if (rwpath \|\| name[0] == '%') {
	67	type = AFSVL_RWVOL;
	68	force = 1;
	69	}
	70
	71	suffix = strrchr(name, '.');
	72	if (suffix) {
	73	if (strcmp(suffix, ".readonly") == 0) {
	74	type = AFSVL_ROVOL;
	75	force = 1;
ec26815a	76	} else if (strcmp(suffix, ".backup") == 0) {
1da177e4 LT	77	type = AFSVL_BACKVOL;
1da177e4 LT	78	force = 1;
ec26815a DH	79	} else if (suffix[1] == 0) {
ec26815a DH	80	} else {
1da177e4 LT	81	suffix = NULL;
	82	}
	83	}
	84
	85	/* split the cell and volume names */
	86	name++;
	87	volname = strchr(name, ':');
	88	if (volname) {
	89	cellname = name;
	90	cellnamesz = volname - name;
	91	volname++;
ec26815a	92	} else {
1da177e4 LT	93	volname = name;
	94	cellname = NULL;
	95	cellnamesz = 0;
	96	}
	97
	98	volnamesz = suffix ? suffix - volname : strlen(volname);
	99
	100	_debug("CELL:%.s [%p] VOLUME:%.s SUFFIX:%s TYPE:%d%s",
	101	cellnamesz, cellnamesz, cellname ?: "", cell,
	102	volnamesz, volnamesz, volname, suffix ?: "-",
	103	type,
	104	force ? " FORCE" : "");
	105
	106	/* lookup the cell record */
	107	if (cellname \|\| !cell) {
08e0e7c8 DH	108	cell = afs_cell_lookup(cellname, cellnamesz);
	109	if (IS_ERR(cell)) {
	110	ret = PTR_ERR(cell);
1da177e4 LT	111	printk("kAFS: unable to lookup cell '%s'\n",
	112	cellname ?: "");
	113	goto error;
	114	}
ec26815a	115	} else {
1da177e4 LT	116	afs_get_cell(cell);
	117	}
	118
	119	/* lookup the volume location record */
08e0e7c8 DH	120	vlocation = afs_vlocation_lookup(cell, volname, volnamesz);
	121	if (IS_ERR(vlocation)) {
	122	ret = PTR_ERR(vlocation);
	123	vlocation = NULL;
1da177e4	124	goto error;
08e0e7c8	125	}
1da177e4 LT	126
	127	/* make the final decision on the type we want */
	128	ret = -ENOMEDIUM;
	129	if (force && !(vlocation->vldb.vidmask & (1 << type)))
	130	goto error;
	131
	132	srvtmask = 0;
	133	for (loop = 0; loop < vlocation->vldb.nservers; loop++)
	134	srvtmask \|= vlocation->vldb.srvtmask[loop];
	135
	136	if (force) {
	137	if (!(srvtmask & (1 << type)))
	138	goto error;
ec26815a	139	} else if (srvtmask & AFS_VOL_VTM_RO) {
1da177e4	140	type = AFSVL_ROVOL;
ec26815a	141	} else if (srvtmask & AFS_VOL_VTM_RW) {
1da177e4	142	type = AFSVL_RWVOL;
ec26815a	143	} else {
1da177e4 LT	144	goto error;
	145	}
	146
	147	down_write(&cell->vl_sem);
	148
	149	/* is the volume already active? */
	150	if (vlocation->vols[type]) {
	151	/* yes - re-use it */
	152	volume = vlocation->vols[type];
	153	afs_get_volume(volume);
	154	goto success;
	155	}
	156
	157	/* create a new volume record */
	158	_debug("creating new volume record");
	159
	160	ret = -ENOMEM;
f8314dc6	161	volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
1da177e4 LT	162	if (!volume)
	163	goto error_up;
	164
1da177e4 LT	165	atomic_set(&volume->usage, 1);
	166	volume->type = type;
	167	volume->type_force = force;
	168	volume->cell = cell;
	169	volume->vid = vlocation->vldb.vid[type];
	170
	171	init_rwsem(&volume->server_sem);
	172
	173	/* look up all the applicable server records */
	174	for (loop = 0; loop < 8; loop++) {
	175	if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
08e0e7c8 DH	176	server = afs_lookup_server(
	177	volume->cell, &vlocation->vldb.servers[loop]);
	178	if (IS_ERR(server)) {
	179	ret = PTR_ERR(server);
1da177e4	180	goto error_discard;
08e0e7c8	181	}
1da177e4	182
08e0e7c8	183	volume->servers[volume->nservers] = server;
1da177e4 LT	184	volume->nservers++;
	185	}
	186	}
	187
	188	/* attach the cache and volume location */
	189	#ifdef AFS_CACHING_SUPPORT
	190	cachefs_acquire_cookie(vlocation->cache,
	191	&afs_vnode_cache_index_def,
	192	volume,
	193	&volume->cache);
	194	#endif
	195
	196	afs_get_vlocation(vlocation);
	197	volume->vlocation = vlocation;
	198
	199	vlocation->vols[type] = volume;
	200
ec26815a	201	success:
1da177e4 LT	202	_debug("kAFS selected %s volume %08x",
1da177e4 LT	203	afs_voltypes[volume->type], volume->vid);
08e0e7c8 DH	204	up_write(&cell->vl_sem);
	205	afs_put_vlocation(vlocation);
	206	afs_put_cell(cell);
	207	_leave(" = %p", volume);
	208	return volume;
1da177e4 LT	209
1da177e4 LT	210	/* clean up */
ec26815a	211	error_up:
1da177e4	212	up_write(&cell->vl_sem);
ec26815a	213	error:
1da177e4 LT	214	afs_put_vlocation(vlocation);
1da177e4 LT	215	afs_put_cell(cell);
08e0e7c8 DH	216	_leave(" = %d", ret);
08e0e7c8 DH	217	return ERR_PTR(ret);
1da177e4	218
ec26815a	219	error_discard:
1da177e4 LT	220	up_write(&cell->vl_sem);
	221
	222	for (loop = volume->nservers - 1; loop >= 0; loop--)
	223	afs_put_server(volume->servers[loop]);
	224
	225	kfree(volume);
	226	goto error;
ec26815a	227	}
1da177e4	228
1da177e4 LT	229	/*
	230	* destroy a volume record
	231	*/
	232	void afs_put_volume(struct afs_volume *volume)
	233	{
	234	struct afs_vlocation *vlocation;
	235	int loop;
	236
	237	if (!volume)
	238	return;
	239
	240	_enter("%p", volume);
	241
08e0e7c8	242	ASSERTCMP(atomic_read(&volume->usage), >, 0);
1da177e4	243
08e0e7c8	244	vlocation = volume->vlocation;
1da177e4 LT	245
	246	/* to prevent a race, the decrement and the dequeue must be effectively
	247	* atomic */
	248	down_write(&vlocation->cell->vl_sem);
	249
	250	if (likely(!atomic_dec_and_test(&volume->usage))) {
	251	up_write(&vlocation->cell->vl_sem);
	252	_leave("");
	253	return;
	254	}
	255
	256	vlocation->vols[volume->type] = NULL;
	257
	258	up_write(&vlocation->cell->vl_sem);
	259
	260	/* finish cleaning up the volume */
	261	#ifdef AFS_CACHING_SUPPORT
	262	cachefs_relinquish_cookie(volume->cache, 0);
	263	#endif
	264	afs_put_vlocation(vlocation);
	265
	266	for (loop = volume->nservers - 1; loop >= 0; loop--)
	267	afs_put_server(volume->servers[loop]);
	268
	269	kfree(volume);
	270
	271	_leave(" [destroyed]");
ec26815a	272	}
1da177e4	273
1da177e4 LT	274	/*
	275	* pick a server to use to try accessing this volume
	276	* - returns with an elevated usage count on the server chosen
	277	*/
08e0e7c8	278	struct afs_server afs_volume_pick_fileserver(struct afs_vnode vnode)
1da177e4	279	{
08e0e7c8	280	struct afs_volume *volume = vnode->volume;
1da177e4 LT	281	struct afs_server *server;
	282	int ret, state, loop;
	283
	284	_enter("%s", volume->vlocation->vldb.name);
	285
08e0e7c8 DH	286	/* stick with the server we're already using if we can */
	287	if (vnode->server && vnode->server->fs_state == 0) {
	288	afs_get_server(vnode->server);
	289	_leave(" = %p [current]", vnode->server);
	290	return vnode->server;
	291	}
	292
1da177e4 LT	293	down_read(&volume->server_sem);
	294
	295	/* handle the no-server case */
	296	if (volume->nservers == 0) {
	297	ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
	298	up_read(&volume->server_sem);
	299	_leave(" = %d [no servers]", ret);
08e0e7c8	300	return ERR_PTR(ret);
1da177e4 LT	301	}
	302
	303	/* basically, just search the list for the first live server and use
	304	* that */
	305	ret = 0;
	306	for (loop = 0; loop < volume->nservers; loop++) {
	307	server = volume->servers[loop];
	308	state = server->fs_state;
	309
08e0e7c8 DH	310	_debug("consider %d [%d]", loop, state);
08e0e7c8 DH	311
1da177e4 LT	312	switch (state) {
	313	/* found an apparently healthy server */
	314	case 0:
	315	afs_get_server(server);
	316	up_read(&volume->server_sem);
08e0e7c8 DH	317	_leave(" = %p (picked %08x)",
	318	server, ntohl(server->addr.s_addr));
	319	return server;
1da177e4 LT	320
	321	case -ENETUNREACH:
	322	if (ret == 0)
	323	ret = state;
	324	break;
	325
	326	case -EHOSTUNREACH:
	327	if (ret == 0 \|\|
	328	ret == -ENETUNREACH)
	329	ret = state;
	330	break;
	331
	332	case -ECONNREFUSED:
	333	if (ret == 0 \|\|
	334	ret == -ENETUNREACH \|\|
	335	ret == -EHOSTUNREACH)
	336	ret = state;
	337	break;
	338
	339	default:
	340	case -EREMOTEIO:
	341	if (ret == 0 \|\|
	342	ret == -ENETUNREACH \|\|
	343	ret == -EHOSTUNREACH \|\|
	344	ret == -ECONNREFUSED)
	345	ret = state;
	346	break;
	347	}
	348	}
	349
	350	/* no available servers
	351	* - TODO: handle the no active servers case better
	352	*/
	353	up_read(&volume->server_sem);
	354	_leave(" = %d", ret);
08e0e7c8	355	return ERR_PTR(ret);
ec26815a	356	}
1da177e4	357
1da177e4 LT	358	/*
	359	* release a server after use
	360	* - releases the ref on the server struct that was acquired by picking
	361	* - records result of using a particular server to access a volume
	362	* - return 0 to try again, 1 if okay or to issue error
	363	*/
08e0e7c8	364	int afs_volume_release_fileserver(struct afs_vnode *vnode,
1da177e4 LT	365	struct afs_server *server,
	366	int result)
	367	{
08e0e7c8	368	struct afs_volume *volume = vnode->volume;
1da177e4 LT	369	unsigned loop;
	370
	371	_enter("%s,%08x,%d",
	372	volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
	373	result);
	374
	375	switch (result) {
	376	/* success */
	377	case 0:
	378	server->fs_act_jif = jiffies;
08e0e7c8	379	server->fs_state = 0;
1da177e4 LT	380	break;
	381
	382	/* the fileserver denied all knowledge of the volume */
	383	case -ENOMEDIUM:
	384	server->fs_act_jif = jiffies;
	385	down_write(&volume->server_sem);
	386
08e0e7c8	387	/* firstly, find where the server is in the active list (if it
1da177e4 LT	388	* is) */
	389	for (loop = 0; loop < volume->nservers; loop++)
	390	if (volume->servers[loop] == server)
	391	goto present;
	392
	393	/* no longer there - may have been discarded by another op */
	394	goto try_next_server_upw;
	395
	396	present:
	397	volume->nservers--;
	398	memmove(&volume->servers[loop],
	399	&volume->servers[loop + 1],
	400	sizeof(volume->servers[loop]) *
	401	(volume->nservers - loop));
	402	volume->servers[volume->nservers] = NULL;
	403	afs_put_server(server);
	404	volume->rjservers++;
	405
	406	if (volume->nservers > 0)
	407	/* another server might acknowledge its existence */
	408	goto try_next_server_upw;
	409
	410	/* handle the case where all the fileservers have rejected the
	411	* volume
	412	* - TODO: try asking the fileservers for volume information
	413	* - TODO: contact the VL server again to see if the volume is
	414	* no longer registered
	415	*/
	416	up_write(&volume->server_sem);
	417	afs_put_server(server);
	418	_leave(" [completely rejected]");
	419	return 1;
	420
	421	/* problem reaching the server */
	422	case -ENETUNREACH:
	423	case -EHOSTUNREACH:
	424	case -ECONNREFUSED:
08e0e7c8	425	case -ETIME:
1da177e4 LT	426	case -ETIMEDOUT:
	427	case -EREMOTEIO:
	428	/* mark the server as dead
	429	* TODO: vary dead timeout depending on error
	430	*/
	431	spin_lock(&server->fs_lock);
	432	if (!server->fs_state) {
	433	server->fs_dead_jif = jiffies + HZ * 10;
	434	server->fs_state = result;
	435	printk("kAFS: SERVER DEAD state=%d\n", result);
	436	}
	437	spin_unlock(&server->fs_lock);
	438	goto try_next_server;
	439
	440	/* miscellaneous error */
	441	default:
	442	server->fs_act_jif = jiffies;
	443	case -ENOMEM:
	444	case -ENONET:
	445	break;
	446	}
	447
	448	/* tell the caller to accept the result */
	449	afs_put_server(server);
	450	_leave("");
	451	return 1;
	452
	453	/* tell the caller to loop around and try the next server */
ec26815a	454	try_next_server_upw:
1da177e4	455	up_write(&volume->server_sem);
ec26815a	456	try_next_server:
1da177e4 LT	457	afs_put_server(server);
	458	_leave(" [try next server]");
	459	return 0;
ec26815a	460	}