initial commit with v2.6.9

[linux-2.6.9-moxart.git] / fs / afs / volume.c

/* volume.c: AFS volume management
 *
 * Copyright (C) 2002 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 "volume.h"
#include "vnode.h"
#include "cell.h"
#include "cache.h"
#include "cmservice.h"
#include "fsclient.h"
#include "vlclient.h"
#include "internal.h"

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

#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_volume_cache_match(void *target,
                                                  const void *entry);
static void afs_volume_cache_update(void *source, void *entry);

struct cachefs_index_def afs_volume_cache_index_def = {
        .name           = "volume",
        .data_size      = sizeof(struct afs_cache_vhash),
        .keys[0]        = { CACHEFS_INDEX_KEYS_BIN, 1 },
        .keys[1]        = { CACHEFS_INDEX_KEYS_BIN, 1 },
        .match          = afs_volume_cache_match,
        .update         = afs_volume_cache_update,
};
#endif

/*****************************************************************************/
/*
 * 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
 */
int afs_volume_lookup(const char *name, struct afs_cell *cell, int rwpath,
                      struct afs_volume **_volume)
{
        struct afs_vlocation *vlocation = NULL;
        struct afs_volume *volume = 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 -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) {
                ret = afs_cell_lookup(cellname, cellnamesz, &cell);
                if (ret<0) {
                        printk("kAFS: unable to lookup cell '%s'\n",
                               cellname ?: "");
                        goto error;
                }
        }
        else {
                afs_get_cell(cell);
        }

        /* lookup the volume location record */
        ret = afs_vlocation_lookup(cell, volname, volnamesz, &vlocation);
        if (ret < 0)
                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 = kmalloc(sizeof(struct afs_volume), GFP_KERNEL);
        if (!volume)
                goto error_up;

        memset(volume, 0, sizeof(struct afs_volume));
        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)) {
                        ret = afs_server_lookup(
                                volume->cell,
                                &vlocation->vldb.servers[loop],
                                &volume->servers[volume->nservers]);
                        if (ret < 0)
                                goto error_discard;

                        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);
        *_volume = volume;
        ret = 0;

        /* clean up */
 error_up:
        up_write(&cell->vl_sem);
 error:
        afs_put_vlocation(vlocation);
        afs_put_cell(cell);

        _leave(" = %d (%p)", ret, volume);
        return 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;
} /* end afs_volume_lookup() */

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

        if (!volume)
                return;

        _enter("%p", volume);

        vlocation = volume->vlocation;

        /* sanity check */
        BUG_ON(atomic_read(&volume->usage) <= 0);

        /* 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]");
} /* end afs_put_volume() */

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

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

        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 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;

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

                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 ret;
} /* end afs_volume_pick_fileserver() */

/*****************************************************************************/
/*
 * 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_volume *volume,
                                  struct afs_server *server,
                                  int result)
{
        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;
                break;

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

                /* first, 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 -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;

} /* end afs_volume_release_fileserver() */

/*****************************************************************************/
/*
 * match a volume hash record stored in the cache
 */
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_volume_cache_match(void *target,
                                                  const void *entry)
{
        const struct afs_cache_vhash *vhash = entry;
        struct afs_volume *volume = target;

        _enter("{%u},{%u}", volume->type, vhash->vtype);

        if (volume->type == vhash->vtype) {
                _leave(" = SUCCESS");
                return CACHEFS_MATCH_SUCCESS;
        }

        _leave(" = FAILED");
        return CACHEFS_MATCH_FAILED;
} /* end afs_volume_cache_match() */
#endif

/*****************************************************************************/
/*
 * update a volume hash record stored in the cache
 */
#ifdef AFS_CACHING_SUPPORT
static void afs_volume_cache_update(void *source, void *entry)
{
        struct afs_cache_vhash *vhash = entry;
        struct afs_volume *volume = source;

        _enter("");

        vhash->vtype = volume->type;

} /* end afs_volume_cache_update() */
#endif