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

 /* 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->net, 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(params->net, vlocation);
 	_leave(" = %p", volume);
 	return volume;

 	/* clean up */
 error_up:
 	up_write(&params->cell->vl_sem);
 error:
 	afs_put_vlocation(params->net, 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_net *net, 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(net, 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;
 }
	/* 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->net, 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(params->net, vlocation);
	_leave(" = %p", volume);
	return volume;

	/* clean up */
	error_up:
	up_write(&params->cell->vl_sem);
	error:
	afs_put_vlocation(params->net, 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_net net, 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(net, 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;
	}