[fs/lustre-release.git] / lustre / ofd / ofd_obd.c

/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/ofd/ofd_obd.c
 *
 * This file contains OBD API methods for OBD Filter Device (OFD) which are
 * used for export handling, configuration purposes and recovery.
 * Several methods are used by ECHO client only since it still uses OBD API.
 * Such methods have _echo_ prefix in name.
 *
 * Author: Andreas Dilger <andreas.dilger@intel.com>
 * Author: Alexey Zhuravlev <alexey.zhuravlev@intel.com>
 * Author: Mikhail Pershin <mike.pershin@intel.com>
 */

#define DEBUG_SUBSYSTEM S_FILTER

#include <lustre/lustre_idl.h>
#include "ofd_internal.h"
#include <obd_cksum.h>
#include <lustre_ioctl.h>
#include <lustre_quota.h>
#include <lustre_lfsck.h>
#include <lustre_nodemap.h>

/**
 * Initialize OFD per-export statistics.
 *
 * This function sets up procfs entries for various OFD export counters. These
 * counters are for per-client statistics tracked on the server.
 *
 * \param[in] ofd        OFD device
 * \param[in] exp        OBD export
 * \param[in] client_nid NID of client
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_export_stats_init(struct ofd_device *ofd,
                                 struct obd_export *exp,
                                 lnet_nid_t *client_nid)
{
        struct obd_device       *obd = ofd_obd(ofd);
        struct nid_stat         *stats;
        int                      rc;
        ENTRY;

        LASSERT(obd->obd_uses_nid_stats);

        if (obd_uuid_equals(&exp->exp_client_uuid, &obd->obd_uuid))
                /* Self-export gets no proc entry */
                RETURN(0);

        rc = lprocfs_exp_setup(exp, client_nid);
        if (rc != 0)
                /* Mask error for already created /proc entries */
                RETURN(rc == -EALREADY ? 0 : rc);

        stats = exp->exp_nid_stats;
        stats->nid_stats = lprocfs_alloc_stats(NUM_OBD_STATS +
                                                LPROC_OFD_STATS_LAST,
                                                LPROCFS_STATS_FLAG_NOPERCPU);
        if (stats->nid_stats == NULL)
                RETURN(-ENOMEM);

        lprocfs_init_ops_stats(LPROC_OFD_STATS_LAST, stats->nid_stats);

        ofd_stats_counter_init(stats->nid_stats);

        rc = lprocfs_register_stats(stats->nid_proc, "stats", stats->nid_stats);
        if (rc != 0) {
                lprocfs_free_stats(&stats->nid_stats);
                GOTO(out, rc);
        }

        rc = lprocfs_nid_ldlm_stats_init(stats);
        if (rc != 0)
                GOTO(out, rc);

out:
        RETURN(rc);
}

/**
 * Match client and OST server connection feature flags.
 *
 * Compute the compatibility flags for a connection request based on
 * features mutually supported by client and server.
 *
 * The obd_export::exp_connect_data.ocd_connect_flags field in \a exp
 * must not be updated here, otherwise a partially initialized value may
 * be exposed. After the connection request is successfully processed,
 * the top-level tgt_connect() request handler atomically updates the export
 * connect flags from the obd_connect_data::ocd_connect_flags field of the
 * reply. \see tgt_connect().
 *
 * \param[in] env               execution environment
 * \param[in] exp               the obd_export associated with this
 *                              client/target pair
 * \param[in] data              stores data for this connect request
 * \param[in] new_connection    is this connection new or not
 *
 * \retval              0 if success
 * \retval              -EPROTO client and server feature requirements are
 *                      incompatible
 * \retval              -EBADF  OST index in connect request doesn't match
 *                      real OST index
 */
static int ofd_parse_connect_data(const struct lu_env *env,
                                  struct obd_export *exp,
                                  struct obd_connect_data *data,
                                  bool new_connection)
{
        struct ofd_device                *ofd = ofd_exp(exp);
        struct filter_export_data        *fed = &exp->exp_filter_data;

        if (!data)
                RETURN(0);

        CDEBUG(D_RPCTRACE, "%s: cli %s/%p ocd_connect_flags: %#llx"
               " ocd_version: %x ocd_grant: %d ocd_index: %u"
               " ocd_group %u\n",
               exp->exp_obd->obd_name, exp->exp_client_uuid.uuid, exp,
               data->ocd_connect_flags, data->ocd_version,
               data->ocd_grant, data->ocd_index, data->ocd_group);

        if (fed->fed_group != 0 && fed->fed_group != data->ocd_group) {
                CWARN("!!! This export (nid %s) used object group %d "
                      "earlier; now it's trying to use group %d!  This could "
                      "be a bug in the MDS. Please report to "
                      "https://jira.hpdd.intel.com/\n",
                      obd_export_nid2str(exp), fed->fed_group,
                      data->ocd_group);
                RETURN(-EPROTO);
        }
        fed->fed_group = data->ocd_group;

        data->ocd_connect_flags &= OST_CONNECT_SUPPORTED;
        data->ocd_connect_flags2 &= OST_CONNECT_SUPPORTED2;
        data->ocd_version = LUSTRE_VERSION_CODE;

        /* Kindly make sure the SKIP_ORPHAN flag is from MDS. */
        if (data->ocd_connect_flags & OBD_CONNECT_MDS)
                CDEBUG(D_HA, "%s: Received MDS connection for group %u\n",
                       exp->exp_obd->obd_name, data->ocd_group);
        else if (data->ocd_connect_flags & OBD_CONNECT_SKIP_ORPHAN)
                RETURN(-EPROTO);

        /* Determine optimal brw size before calculating grant */
        if (OBD_FAIL_CHECK(OBD_FAIL_OST_BRW_SIZE)) {
                data->ocd_brw_size = 65536;
        } else if (OCD_HAS_FLAG(data, BRW_SIZE)) {
                if (data->ocd_brw_size > ofd->ofd_brw_size)
                        data->ocd_brw_size = ofd->ofd_brw_size;
                if (data->ocd_brw_size == 0) {
                        CERROR("%s: cli %s/%p ocd_connect_flags: %#llx"
                               " ocd_version: %x ocd_grant: %d ocd_index: %u "
                               "ocd_brw_size is unexpectedly zero, "
                               "network data corruption?"
                               "Refusing connection of this client\n",
                               exp->exp_obd->obd_name,
                               exp->exp_client_uuid.uuid,
                               exp, data->ocd_connect_flags, data->ocd_version,
                               data->ocd_grant, data->ocd_index);
                        RETURN(-EPROTO);
                }
        }

        if (OCD_HAS_FLAG(data, GRANT_PARAM)) {
                /* client is reporting its page size, for future use */
                exp->exp_filter_data.fed_pagebits = data->ocd_grant_blkbits;
                data->ocd_grant_blkbits  = ofd->ofd_blockbits;
                /* ddp_inodespace may not be power-of-two value, eg. for ldiskfs
                 * it's LDISKFS_DIR_REC_LEN(20) = 28. */
                data->ocd_grant_inobits =
                                       fls(ofd->ofd_dt_conf.ddp_inodespace - 1);
                /* ocd_grant_tax_kb is in 1K byte blocks */
                data->ocd_grant_tax_kb = ofd->ofd_dt_conf.ddp_extent_tax >> 10;
                data->ocd_grant_max_blks = ofd->ofd_dt_conf.ddp_max_extent_blks;
        }

        if (OCD_HAS_FLAG(data, GRANT)) {
                /* Save connect_data we have so far because ofd_grant_connect()
                 * uses it to calculate grant. */
                exp->exp_connect_data = *data;
                ofd_grant_connect(env, exp, data, new_connection);
        }

        if (data->ocd_connect_flags & OBD_CONNECT_INDEX) {
                struct lr_server_data *lsd = &ofd->ofd_lut.lut_lsd;
                int                    index = lsd->lsd_osd_index;

                if (index != data->ocd_index) {
                        LCONSOLE_ERROR_MSG(0x136, "Connection from %s to index"
                                           " %u doesn't match actual OST index"
                                           " %u in last_rcvd file, bad "
                                           "configuration?\n",
                                           obd_export_nid2str(exp), index,
                                           data->ocd_index);
                        RETURN(-EBADF);
                }
                if (!(lsd->lsd_feature_compat & OBD_COMPAT_OST)) {
                        /* this will only happen on the first connect */
                        lsd->lsd_feature_compat |= OBD_COMPAT_OST;
                        /* sync is not needed here as lut_client_add will
                         * set exp_need_sync flag */
                        tgt_server_data_update(env, &ofd->ofd_lut, 0);
                }
        }

        if (data->ocd_connect_flags & OBD_CONNECT_CKSUM) {
                __u32 cksum_types = data->ocd_cksum_types;

                /* The client set in ocd_cksum_types the checksum types it
                 * supports. We have to mask off the algorithms that we don't
                 * support */
                data->ocd_cksum_types &= cksum_types_supported_server();

                if (unlikely(data->ocd_cksum_types == 0)) {
                        CERROR("%s: Connect with checksum support but no "
                               "ocd_cksum_types is set\n",
                               exp->exp_obd->obd_name);
                        RETURN(-EPROTO);
                }

                CDEBUG(D_RPCTRACE, "%s: cli %s supports cksum type %x, return "
                       "%x\n", exp->exp_obd->obd_name, obd_export_nid2str(exp),
                       cksum_types, data->ocd_cksum_types);
        } else {
                /* This client does not support OBD_CONNECT_CKSUM
                 * fall back to CRC32 */
                CDEBUG(D_RPCTRACE, "%s: cli %s does not support "
                       "OBD_CONNECT_CKSUM, CRC32 will be used\n",
                       exp->exp_obd->obd_name, obd_export_nid2str(exp));
        }

        if (data->ocd_connect_flags & OBD_CONNECT_MAXBYTES)
                data->ocd_maxbytes = ofd->ofd_dt_conf.ddp_maxbytes;

        if (OCD_HAS_FLAG(data, PINGLESS)) {
                if (ptlrpc_pinger_suppress_pings()) {
                        spin_lock(&exp->exp_obd->obd_dev_lock);
                        list_del_init(&exp->exp_obd_chain_timed);
                        spin_unlock(&exp->exp_obd->obd_dev_lock);
                } else {
                        data->ocd_connect_flags &= ~OBD_CONNECT_PINGLESS;
                }
        }

        RETURN(0);
}

/**
 * Re-initialize export upon client reconnection.
 *
 * This function parses connection data from reconnect and resets
 * export statistics.
 *
 * \param[in] env       execution environment
 * \param[in] exp       OBD export
 * \param[in] obd       OFD device
 * \param[in] cluuid    NID of client
 * \param[in] data      connection data from request
 * \param[in] localdata client NID
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_obd_reconnect(const struct lu_env *env, struct obd_export *exp,
                             struct obd_device *obd, struct obd_uuid *cluuid,
                             struct obd_connect_data *data,
                             void *client_nid)
{
        struct ofd_device       *ofd;
        int                      rc;

        ENTRY;

        if (exp == NULL || obd == NULL || cluuid == NULL)
                RETURN(-EINVAL);

        rc = nodemap_add_member(*(lnet_nid_t *)client_nid, exp);
        if (rc != 0 && rc != -EEXIST)
                RETURN(rc);

        ofd = ofd_dev(obd->obd_lu_dev);

        rc = ofd_parse_connect_data(env, exp, data, false);
        if (rc == 0)
                ofd_export_stats_init(ofd, exp, client_nid);
        else
                nodemap_del_member(exp);

        RETURN(rc);
}

/**
 * Initialize new client connection.
 *
 * This function handles new connection to the OFD. The new export is
 * created (in context of class_connect()) and persistent client data is
 * initialized on storage.
 *
 * \param[in] env       execution environment
 * \param[out] _exp     stores pointer to new export
 * \param[in] obd       OFD device
 * \param[in] cluuid    client UUID
 * \param[in] data      connection data from request
 * \param[in] localdata client NID
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_obd_connect(const struct lu_env *env, struct obd_export **_exp,
                           struct obd_device *obd, struct obd_uuid *cluuid,
                           struct obd_connect_data *data, void *localdata)
{
        struct obd_export       *exp;
        struct ofd_device       *ofd;
        struct lustre_handle     conn = { 0 };
        int                      rc;
        ENTRY;

        if (_exp == NULL || obd == NULL || cluuid == NULL)
                RETURN(-EINVAL);

        ofd = ofd_dev(obd->obd_lu_dev);

        rc = class_connect(&conn, obd, cluuid);
        if (rc)
                RETURN(rc);

        exp = class_conn2export(&conn);
        LASSERT(exp != NULL);

        if (localdata != NULL) {
                rc = nodemap_add_member(*(lnet_nid_t *)localdata, exp);
                if (rc != 0 && rc != -EEXIST)
                        GOTO(out, rc);
        } else {
                CDEBUG(D_HA, "%s: cannot find nodemap for client %s: "
                       "nid is null\n", obd->obd_name, cluuid->uuid);
        }

        rc = ofd_parse_connect_data(env, exp, data, true);
        if (rc)
                GOTO(out, rc);

        if (obd->obd_replayable) {
                struct tg_export_data *ted = &exp->exp_target_data;

                memcpy(ted->ted_lcd->lcd_uuid, cluuid,
                       sizeof(ted->ted_lcd->lcd_uuid));
                rc = tgt_client_new(env, exp);
                if (rc != 0)
                        GOTO(out, rc);
                ofd_export_stats_init(ofd, exp, localdata);
        }

        CDEBUG(D_HA, "%s: get connection from MDS %d\n", obd->obd_name,
               data ? data->ocd_group : -1);

out:
        if (rc != 0) {
                class_disconnect(exp);
                nodemap_del_member(exp);
                *_exp = NULL;
        } else {
                *_exp = exp;
        }
        RETURN(rc);
}

/**
 * Disconnect a connected client.
 *
 * This function terminates the client connection. The client export is
 * disconnected (cleaned up) and client data on persistent storage is removed.
 *
 * \param[in] exp       OBD export
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
int ofd_obd_disconnect(struct obd_export *exp)
{
        struct ofd_device       *ofd = ofd_exp(exp);
        struct lu_env            env;
        int                      rc;

        ENTRY;

        LASSERT(exp);
        class_export_get(exp);

        if (!(exp->exp_flags & OBD_OPT_FORCE))
                ofd_grant_sanity_check(ofd_obd(ofd), __FUNCTION__);

        rc = server_disconnect_export(exp);

        ofd_grant_discard(exp);

        /* Do not erase record for recoverable client. */
        if (exp->exp_obd->obd_replayable &&
            (!exp->exp_obd->obd_fail || exp->exp_failed)) {
                rc = lu_env_init(&env, LCT_DT_THREAD);
                if (rc)
                        GOTO(out, rc);

                tgt_client_del(&env, exp);
                lu_env_fini(&env);
        }
out:
        nodemap_del_member(exp);
        class_export_put(exp);
        RETURN(rc);
}

/**
 * Implementation of obd_ops::o_init_export.
 *
 * This function is called from class_new_export() and initializes
 * the OFD-specific data for new export.
 *
 * \param[in] exp       OBD export
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_init_export(struct obd_export *exp)
{
        int rc;

        spin_lock_init(&exp->exp_filter_data.fed_lock);
        INIT_LIST_HEAD(&exp->exp_filter_data.fed_mod_list);
        atomic_set(&exp->exp_filter_data.fed_soft_sync_count, 0);
        spin_lock(&exp->exp_lock);
        exp->exp_connecting = 1;
        spin_unlock(&exp->exp_lock);

        /* self-export doesn't need client data and ldlm initialization */
        if (unlikely(obd_uuid_equals(&exp->exp_obd->obd_uuid,
                                     &exp->exp_client_uuid)))
                return 0;

        rc = tgt_client_alloc(exp);
        if (rc == 0)
                ldlm_init_export(exp);
        if (rc)
                CERROR("%s: Can't initialize export: rc %d\n",
                       exp->exp_obd->obd_name, rc);
        return rc;
}

/**
 * Implementation of obd_ops::o_destroy_export.
 *
 * This function is called from class_export_destroy() to cleanup
 * the OFD-specific data for export being destroyed.
 *
 * \param[in] exp       OBD export
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_destroy_export(struct obd_export *exp)
{
        struct ofd_device *ofd = ofd_exp(exp);

        if (exp->exp_filter_data.fed_pending)
                CERROR("%s: cli %s/%p has %lu pending on destroyed export"
                       "\n", exp->exp_obd->obd_name, exp->exp_client_uuid.uuid,
                       exp, exp->exp_filter_data.fed_pending);

        target_destroy_export(exp);

        if (unlikely(obd_uuid_equals(&exp->exp_obd->obd_uuid,
                                     &exp->exp_client_uuid)))
                return 0;

        ldlm_destroy_export(exp);
        tgt_client_free(exp);

        ofd_fmd_cleanup(exp);

        /*
         * discard grants once we're sure no more
         * interaction with the client is possible
         */
        ofd_grant_discard(exp);
        ofd_fmd_cleanup(exp);

        if (exp_connect_flags(exp) & OBD_CONNECT_GRANT)
                ofd->ofd_tot_granted_clients--;

        if (!(exp->exp_flags & OBD_OPT_FORCE))
                ofd_grant_sanity_check(exp->exp_obd, __FUNCTION__);

        LASSERT(list_empty(&exp->exp_filter_data.fed_mod_list));
        return 0;
}

/**
 * Notify all devices in server stack about recovery completion.
 *
 * This function calls ldo_recovery_complete() for all lower devices in the
 * server stack so they will be prepared for normal operations.
 *
 * \param[in] env       execution environment
 * \param[in] ofd       OFD device
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
int ofd_postrecov(const struct lu_env *env, struct ofd_device *ofd)
{
        struct lu_device *ldev = &ofd->ofd_dt_dev.dd_lu_dev;
        int rc;

        CDEBUG(D_HA, "%s: recovery is over\n", ofd_name(ofd));

        if (!ofd->ofd_skip_lfsck) {
                struct lfsck_start_param lsp;

                lsp.lsp_start = NULL;
                lsp.lsp_index_valid = 0;
                rc = lfsck_start(env, ofd->ofd_osd, &lsp);
                if (rc != 0 && rc != -EALREADY)
                        CWARN("%s: auto trigger paused LFSCK failed: rc = %d\n",
                              ofd_name(ofd), rc);
        }

        return ldev->ld_ops->ldo_recovery_complete(env, ldev);
}

/**
 * Implementation of obd_ops::o_postrecov.
 *
 * This function is called from target_finish_recovery() upon recovery
 * completion.
 *
 * \param[in] obd       OBD device of OFD
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_obd_postrecov(struct obd_device *obd)
{
        struct lu_env            env;
        struct lu_device        *ldev = obd->obd_lu_dev;
        int                      rc;

        ENTRY;

        rc = lu_env_init(&env, LCT_DT_THREAD);
        if (rc)
                RETURN(rc);
        ofd_info_init(&env, obd->obd_self_export);

        rc = ofd_postrecov(&env, ofd_dev(ldev));

        lu_env_fini(&env);
        RETURN(rc);
}

/**
 * Implementation of obd_ops::o_set_info_async.
 *
 * This function is not called from request handler, it is only used by
 * class_notify_sptlrpc_conf() locally by direct obd_set_info_async() call.
 * \see  ofd_set_info_hdl() for request handler function.
 *
 * \param[in] env       execution environment
 * \param[in] exp       OBD export of OFD device
 * \param[in] keylen    length of \a key
 * \param[in] key       key name
 * \param[in] vallen    length of \a val
 * \param[in] val       the \a key value
 * \param[in] set       not used in OFD
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_set_info_async(const struct lu_env *env, struct obd_export *exp,
                              __u32 keylen, void *key, __u32 vallen, void *val,
                              struct ptlrpc_request_set *set)
{
        int rc = 0;

        ENTRY;

        if (exp->exp_obd == NULL) {
                CDEBUG(D_IOCTL, "invalid export %p\n", exp);
                RETURN(-EINVAL);
        }

        if (KEY_IS(KEY_SPTLRPC_CONF)) {
                rc = tgt_adapt_sptlrpc_conf(class_exp2tgt(exp), 0);
        } else {
                CERROR("%s: Unsupported key %s\n",
                       exp->exp_obd->obd_name, (char*)key);
                rc = -EOPNOTSUPP;
        }
        RETURN(rc);
}

/**
 * Implementation of obd_ops::o_get_info.
 *
 * This function is not called from request handler, it is only used by
 * direct call from nrs_orr_range_fill_physical() in ptlrpc, see LU-3239.
 *
 * \see  ofd_get_info_hdl() for request handler function.
 *
 * \param[in]  env      execution environment
 * \param[in]  exp      OBD export of OFD device
 * \param[in]  keylen   length of \a key
 * \param[in]  key      key name
 * \param[out] vallen   length of key value
 * \param[out] val      the key value to return
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_get_info(const struct lu_env *env, struct obd_export *exp,
                        __u32 keylen, void *key, __u32 *vallen, void *val)
{
        struct ofd_thread_info          *info;
        struct ofd_device               *ofd;
        struct ll_fiemap_info_key       *fm_key = key;
        struct fiemap                   *fiemap = val;
        int                              rc = 0;

        ENTRY;

        if (exp->exp_obd == NULL) {
                CDEBUG(D_IOCTL, "invalid client export %p\n", exp);
                RETURN(-EINVAL);
        }

        ofd = ofd_exp(exp);

        if (KEY_IS(KEY_FIEMAP)) {
                info = ofd_info_init(env, exp);

                rc = ostid_to_fid(&info->fti_fid, &fm_key->lfik_oa.o_oi,
                                  ofd->ofd_lut.lut_lsd.lsd_osd_index);
                if (rc != 0)
                        RETURN(rc);

                rc = ofd_fiemap_get(env, ofd, &info->fti_fid, fiemap);
        } else {
                CERROR("%s: not supported key %s\n", ofd_name(ofd), (char*)key);
                rc = -EOPNOTSUPP;
        }

        RETURN(rc);
}

/**
 * Get file system statistics of OST server.
 *
 * Helper function for ofd_statfs(), also used by grant code.
 * Implements caching for statistics to avoid calling OSD device each time.
 *
 * \param[in]  env        execution environment
 * \param[in]  ofd        OFD device
 * \param[out] osfs       statistic data to return
 * \param[in]  max_age    maximum age for cached data
 * \param[in]  from_cache show that data was get from cache or not
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
int ofd_statfs_internal(const struct lu_env *env, struct ofd_device *ofd,
                        struct obd_statfs *osfs, __u64 max_age, int *from_cache)
{
        int rc = 0;
        ENTRY;

        spin_lock(&ofd->ofd_osfs_lock);
        if (cfs_time_before_64(ofd->ofd_osfs_age, max_age) || max_age == 0) {
                u64 unstable;

                /* statfs data are too old, get up-to-date one.
                 * we must be cautious here since multiple threads might be
                 * willing to update statfs data concurrently and we must
                 * grant that cached statfs data are always consistent */

                if (ofd->ofd_statfs_inflight == 0)
                        /* clear inflight counter if no users, although it would
                         * take a while to overflow this 64-bit counter ... */
                        ofd->ofd_osfs_inflight = 0;
                /* notify ofd_grant_commit() that we want to track writes
                 * completed as of now */
                ofd->ofd_statfs_inflight++;
                /* record value of inflight counter before running statfs to
                 * compute the diff once statfs is completed */
                unstable = ofd->ofd_osfs_inflight;
                spin_unlock(&ofd->ofd_osfs_lock);

                /* statfs can sleep ... hopefully not for too long since we can
                 * call it fairly often as space fills up */
                rc = dt_statfs(env, ofd->ofd_osd, osfs);
                if (unlikely(rc))
                        GOTO(out, rc);

                spin_lock(&ofd->ofd_grant_lock);
                spin_lock(&ofd->ofd_osfs_lock);
                /* calculate how much space was written while we released the
                 * ofd_osfs_lock */
                unstable = ofd->ofd_osfs_inflight - unstable;
                ofd->ofd_osfs_unstable = 0;
                if (unstable) {
                        /* some writes committed while we were running statfs
                         * w/o the ofd_osfs_lock. Those ones got added to
                         * the cached statfs data that we are about to crunch.
                         * Take them into account in the new statfs data */
                        osfs->os_bavail -= min_t(u64, osfs->os_bavail,
                                               unstable >> ofd->ofd_blockbits);
                        /* However, we don't really know if those writes got
                         * accounted in the statfs call, so tell
                         * ofd_grant_space_left() there is some uncertainty
                         * on the accounting of those writes.
                         * The purpose is to prevent spurious error messages in
                         * ofd_grant_space_left() since those writes might be
                         * accounted twice. */
                        ofd->ofd_osfs_unstable += unstable;
                }
                /* similarly, there is some uncertainty on write requests
                 * between prepare & commit */
                ofd->ofd_osfs_unstable += ofd->ofd_tot_pending;
                spin_unlock(&ofd->ofd_grant_lock);

                /* finally udpate cached statfs data */
                ofd->ofd_osfs = *osfs;
                ofd->ofd_osfs_age = cfs_time_current_64();

                ofd->ofd_statfs_inflight--; /* stop tracking */
                if (ofd->ofd_statfs_inflight == 0)
                        ofd->ofd_osfs_inflight = 0;
                spin_unlock(&ofd->ofd_osfs_lock);

                if (from_cache)
                        *from_cache = 0;
        } else {
                /* use cached statfs data */
                *osfs = ofd->ofd_osfs;
                spin_unlock(&ofd->ofd_osfs_lock);
                if (from_cache)
                        *from_cache = 1;
        }
        GOTO(out, rc);

out:
        return rc;
}

/**
 * Implementation of obd_ops::o_statfs.
 *
 * This function returns information about a storage file system.
 * It is called from several places by using the OBD API as well as
 * by direct call, e.g. from request handler.
 *
 * \see  ofd_statfs_hdl() for request handler function.
 *
 * Report also the state of the OST to the caller in osfs->os_state
 * (OS_STATE_READONLY, OS_STATE_DEGRADED).
 *
 * \param[in]  env      execution environment
 * \param[in]  exp      OBD export of OFD device
 * \param[out] osfs     statistic data to return
 * \param[in]  max_age  maximum age for cached data
 * \param[in]  flags    not used in OFD
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
int ofd_statfs(const struct lu_env *env,  struct obd_export *exp,
               struct obd_statfs *osfs, __u64 max_age, __u32 flags)
{
        struct obd_device       *obd = class_exp2obd(exp);
        struct ofd_device       *ofd = ofd_exp(exp);
        int                      rc;

        ENTRY;

        rc = ofd_statfs_internal(env, ofd, osfs, max_age, NULL);
        if (unlikely(rc))
                GOTO(out, rc);

        /* at least try to account for cached pages.  its still racy and
         * might be under-reporting if clients haven't announced their
         * caches with brw recently */

        CDEBUG(D_SUPER | D_CACHE, "blocks cached %llu granted %llu"
               " pending %llu free %llu avail %llu\n",
               ofd->ofd_tot_dirty, ofd->ofd_tot_granted, ofd->ofd_tot_pending,
               osfs->os_bfree << ofd->ofd_blockbits,
               osfs->os_bavail << ofd->ofd_blockbits);

        osfs->os_bavail -= min_t(u64, osfs->os_bavail,
                                 ((ofd->ofd_tot_dirty + ofd->ofd_tot_pending +
                                   osfs->os_bsize - 1) >> ofd->ofd_blockbits));

        /* The QoS code on the MDS does not care about space reserved for
         * precreate, so take it out. */
        if (exp_connect_flags(exp) & OBD_CONNECT_MDS) {
                struct filter_export_data *fed;

                fed = &obd->obd_self_export->exp_filter_data;
                osfs->os_bavail -= min_t(u64, osfs->os_bavail,
                                         fed->fed_grant >> ofd->ofd_blockbits);
        }

        ofd_grant_sanity_check(obd, __FUNCTION__);
        CDEBUG(D_CACHE, "%llu blocks: %llu free, %llu avail; "
               "%llu objects: %llu free; state %x\n",
               osfs->os_blocks, osfs->os_bfree, osfs->os_bavail,
               osfs->os_files, osfs->os_ffree, osfs->os_state);

        if (OBD_FAIL_CHECK_VALUE(OBD_FAIL_OST_ENOINO,
                                 ofd->ofd_lut.lut_lsd.lsd_osd_index))
                osfs->os_ffree = 0;

        /* OS_STATE_READONLY can be set by OSD already */
        if (ofd->ofd_raid_degraded)
                osfs->os_state |= OS_STATE_DEGRADED;

        if (obd->obd_self_export != exp && !ofd_grant_param_supp(exp) &&
            ofd->ofd_blockbits > COMPAT_BSIZE_SHIFT) {
                /* clients which don't support OBD_CONNECT_GRANT_PARAM
                 * should not see a block size > page size, otherwise
                 * cl_lost_grant goes mad. Therefore, we emulate a 4KB (=2^12)
                 * block size which is the biggest block size known to work
                 * with all client's page size. */
                osfs->os_blocks <<= ofd->ofd_blockbits - COMPAT_BSIZE_SHIFT;
                osfs->os_bfree  <<= ofd->ofd_blockbits - COMPAT_BSIZE_SHIFT;
                osfs->os_bavail <<= ofd->ofd_blockbits - COMPAT_BSIZE_SHIFT;
                osfs->os_bsize    = 1 << COMPAT_BSIZE_SHIFT;
        }

        if (OBD_FAIL_CHECK_VALUE(OBD_FAIL_OST_ENOSPC,
                                 ofd->ofd_lut.lut_lsd.lsd_osd_index))
                osfs->os_bfree = osfs->os_bavail = 2;

        EXIT;
out:
        return rc;
}

/**
 * Implementation of obd_ops::o_setattr.
 *
 * This function is only used by ECHO client when it is run on top of OFD,
 * \see  ofd_setattr_hdl() for request handler function.

 * \param[in] env       execution environment
 * \param[in] exp       OBD export of OFD device
 * \param[in] oa        setattr parameters
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_echo_setattr(const struct lu_env *env, struct obd_export *exp,
                            struct obdo *oa)
{
        struct ofd_thread_info  *info;
        struct ofd_device       *ofd = ofd_exp(exp);
        struct ldlm_namespace   *ns = ofd->ofd_namespace;
        struct ldlm_resource    *res;
        struct ofd_object       *fo;
        struct lu_fid           *fid = &oa->o_oi.oi_fid;
        struct filter_fid       *ff = NULL;
        int                      rc = 0;

        ENTRY;

        info = ofd_info_init(env, exp);

        ost_fid_build_resid(fid, &info->fti_resid);

        /* This would be very bad - accidentally truncating a file when
         * changing the time or similar - bug 12203. */
        if (oa->o_valid & OBD_MD_FLSIZE) {
                static char mdsinum[48];

                if (oa->o_valid & OBD_MD_FLFID)
                        snprintf(mdsinum, sizeof(mdsinum) - 1,
                                 "of parent "DFID, oa->o_parent_seq,
                                 oa->o_parent_oid, 0);
                else
                        mdsinum[0] = '\0';

                CERROR("%s: setattr from %s trying to truncate object "DFID
                       " %s\n", ofd_name(ofd), obd_export_nid2str(exp),
                       PFID(fid), mdsinum);
                GOTO(out, rc = -EPERM);
        }

        fo = ofd_object_find_exists(env, ofd, fid);
        if (IS_ERR(fo)) {
                CERROR("%s: can't find object "DFID"\n",
                       ofd_name(ofd), PFID(fid));
                GOTO(out, rc = PTR_ERR(fo));
        }

        la_from_obdo(&info->fti_attr, oa, oa->o_valid);
        info->fti_attr.la_valid &= ~LA_TYPE;

        if (oa->o_valid & OBD_MD_FLFID) {
                ff = &info->fti_mds_fid;
                ofd_prepare_fidea(ff, oa);
        }

        /* setting objects attributes (including owner/group) */
        rc = ofd_attr_set(env, fo, &info->fti_attr, ff);
        if (rc)
                GOTO(out_unlock, rc);

        ofd_counter_incr(exp, LPROC_OFD_STATS_SETATTR, NULL, 1);
        EXIT;
out_unlock:
        ofd_object_put(env, fo);
out:
        if (rc == 0) {
                /* we do not call this before to avoid lu_object_find() in
                 *  ->lvbo_update() holding another reference on the object.
                 * otherwise concurrent destroy can make the object unavailable
                 * for 2nd lu_object_find() waiting for the first reference
                 * to go... deadlock! */
                res = ldlm_resource_get(ns, NULL, &info->fti_resid, LDLM_EXTENT, 0);
                if (!IS_ERR(res)) {
                        ldlm_res_lvbo_update(res, NULL, 0);
                        ldlm_resource_putref(res);
                }
        }

        return rc;
}

/**
 * Destroy OFD object by its FID.
 *
 * Supplemental function to destroy object by FID, it is used by request
 * handler and by ofd_echo_destroy() below to find object by FID, lock it
 * and call ofd_object_destroy() finally.
 *
 * \param[in] env       execution environment
 * \param[in] ofd       OFD device
 * \param[in] fid       FID of object
 * \param[in] orphan    set if object being destroyed is an orphan
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
int ofd_destroy_by_fid(const struct lu_env *env, struct ofd_device *ofd,
                       const struct lu_fid *fid, int orphan)
{
        struct ofd_thread_info *info = ofd_info(env);
        struct lustre_handle lockh;
        union ldlm_policy_data policy = { .l_extent = { 0, OBD_OBJECT_EOF } };
        struct ofd_object *fo;
        __u64 flags = LDLM_FL_AST_DISCARD_DATA;
        __u64 rc = 0;

        ENTRY;

        fo = ofd_object_find_exists(env, ofd, fid);
        if (IS_ERR(fo))
                RETURN(PTR_ERR(fo));

        /* Tell the clients that the object is gone now and that they should
         * throw away any cached pages. */
        ost_fid_build_resid(fid, &info->fti_resid);
        rc = ldlm_cli_enqueue_local(ofd->ofd_namespace, &info->fti_resid,
                                    LDLM_EXTENT, &policy, LCK_PW, &flags,
                                    ldlm_blocking_ast, ldlm_completion_ast,
                                    NULL, NULL, 0, LVB_T_NONE, NULL, &lockh);

        /* We only care about the side-effects, just drop the lock. */
        if (rc == ELDLM_OK)
                ldlm_lock_decref(&lockh, LCK_PW);

        LASSERT(fo != NULL);

        rc = ofd_object_destroy(env, fo, orphan);
        EXIT;

        ofd_object_put(env, fo);
        RETURN(rc);
}

/**
 * Implementation of obd_ops::o_destroy.
 *
 * This function is only used by ECHO client when it is run on top of OFD,
 * \see  ofd_destroy_hdl() for request handler function.

 * \param[in] env       execution environment
 * \param[in] exp       OBD export of OFD device
 * \param[in] oa        obdo structure with FID
 *
 * Note: this is OBD API method which is common API for server OBDs and
 * client OBDs. Thus some parameters used in client OBDs may not be used
 * on server OBDs and vice versa.
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_echo_destroy(const struct lu_env *env, struct obd_export *exp,
                            struct obdo *oa)
{
        struct ofd_device       *ofd = ofd_exp(exp);
        struct lu_fid           *fid = &oa->o_oi.oi_fid;
        int                      rc = 0;

        ENTRY;

        ofd_info_init(env, exp);

        CDEBUG(D_HA, "%s: Destroy object "DFID"\n", ofd_name(ofd), PFID(fid));

        rc = ofd_destroy_by_fid(env, ofd, fid, 0);
        if (rc == -ENOENT) {
                CDEBUG(D_INODE, "%s: destroying non-existent object "DFID"\n",
                       ofd_name(ofd), PFID(fid));
                GOTO(out, rc);
        } else if (rc != 0) {
                CERROR("%s: error destroying object "DFID": %d\n",
                       ofd_name(ofd), PFID(fid), rc);
                GOTO(out, rc);
        }
        EXIT;
out:
        return rc;
}

/**
 * Implementation of obd_ops::o_create.
 *
 * This function is only used by ECHO client when it is run on top of OFD
 * and just creates an object.
 * \see  ofd_create_hdl() for request handler function.
 *
 * \param[in]  env      execution environment
 * \param[in]  exp      OBD export of OFD device
 * \param[in]  oa       obdo structure with FID sequence to use
 *
 * Note: this is OBD API method which is common API for server OBDs and
 * client OBDs. Thus some parameters used in client OBDs may not be used
 * on server OBDs and vice versa.
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_echo_create(const struct lu_env *env, struct obd_export *exp,
                           struct obdo *oa)
{
        struct ofd_device       *ofd = ofd_exp(exp);
        struct ofd_thread_info  *info;
        u64                      seq = ostid_seq(&oa->o_oi);
        struct ofd_seq          *oseq;
        int                      rc = 0, diff = 1;
        long                     granted;
        u64                      next_id;
        int                      count;

        ENTRY;

        info = ofd_info_init(env, exp);

        LASSERT(seq == FID_SEQ_ECHO);
        LASSERT(oa->o_valid & OBD_MD_FLGROUP);

        CDEBUG(D_INFO, "ofd_create("DOSTID")\n", POSTID(&oa->o_oi));

        down_read(&ofd->ofd_lastid_rwsem);
        /* Currently, for safe, we do not distinguish which LAST_ID is broken,
         * we may do that in the future.
         * Return -ENOSPC until the LAST_ID rebuilt. */
        if (unlikely(ofd->ofd_lastid_rebuilding))
                GOTO(out_sem, rc = -ENOSPC);

        oseq = ofd_seq_load(env, ofd, seq);
        if (IS_ERR(oseq)) {
                CERROR("%s: Can't find FID Sequence %#llx: rc = %ld\n",
                       ofd_name(ofd), seq, PTR_ERR(oseq));
                GOTO(out_sem, rc = -EINVAL);
        }

        mutex_lock(&oseq->os_create_lock);
        granted = ofd_grant_create(env, ofd_obd(ofd)->obd_self_export, &diff);
        if (granted < 0) {
                rc = granted;
                granted = 0;
                CDEBUG(D_HA, "%s: failed to acquire grant space for "
                       "precreate (%d): rc = %d\n", ofd_name(ofd), diff, rc);
                diff = 0;
                GOTO(out, rc);
        }

        next_id = ofd_seq_last_oid(oseq) + 1;
        count = ofd_precreate_batch(ofd, diff);

        rc = ofd_precreate_objects(env, ofd, next_id, oseq, count, 0);
        if (rc < 0) {
                CERROR("%s: unable to precreate: rc = %d\n",
                       ofd_name(ofd), rc);
        } else {
                ostid_set_id(&oa->o_oi, ofd_seq_last_oid(oseq));
                oa->o_valid |= OBD_MD_FLID | OBD_MD_FLGROUP;
                rc = 0;
        }

        ofd_grant_commit(ofd_obd(ofd)->obd_self_export, granted, rc);
out:
        mutex_unlock(&oseq->os_create_lock);
        ofd_seq_put(env, oseq);

out_sem:
        up_read(&ofd->ofd_lastid_rwsem);
        RETURN(rc);
}

/**
 * Implementation of obd_ops::o_getattr.
 *
 * This function is only used by ECHO client when it is run on top of OFD
 * and returns attributes of object.
 * \see  ofd_getattr_hdl() for request handler function.
 *
 * \param[in]     env   execution environment
 * \param[in]     exp   OBD export of OFD device
 * \param[in,out] oa    contains FID of object to get attributes from and
 *                      is used to return attributes back
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_echo_getattr(const struct lu_env *env, struct obd_export *exp,
                            struct obdo *oa)
{
        struct ofd_device       *ofd = ofd_exp(exp);
        struct ofd_thread_info  *info;
        struct lu_fid           *fid = &oa->o_oi.oi_fid;
        struct ofd_object       *fo;
        int                      rc = 0;

        ENTRY;

        info = ofd_info_init(env, exp);

        fo = ofd_object_find_exists(env, ofd, fid);
        if (IS_ERR(fo))
                GOTO(out, rc = PTR_ERR(fo));

        LASSERT(fo != NULL);
        rc = ofd_attr_get(env, fo, &info->fti_attr);
        oa->o_valid = OBD_MD_FLID;
        if (rc == 0) {
                __u64 curr_version;

                obdo_from_la(oa, &info->fti_attr,
                             OFD_VALID_FLAGS | LA_UID | LA_GID);

                /* Store object version in reply */
                curr_version = dt_version_get(env, ofd_object_child(fo));
                if ((__s64)curr_version != -EOPNOTSUPP) {
                        oa->o_valid |= OBD_MD_FLDATAVERSION;
                        oa->o_data_version = curr_version;
                }
        }

        ofd_object_put(env, fo);
out:
        RETURN(rc);
}

/**
 * Get object version for OBD_IOC_GET_OBJ_VERSION ioctl.
 *
 * This is supplemental function for ofd_iocontrol() to return object
 * version for lctl tool.
 *
 * \param[in]  env      execution environment
 * \param[in]  ofd      OFD device
 * \param[out] karg     ioctl data
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_ioc_get_obj_version(const struct lu_env *env,
                                   struct ofd_device *ofd, void *karg)
{
        struct obd_ioctl_data *data = karg;
        struct lu_fid          fid;
        struct ofd_object     *fo;
        dt_obj_version_t       version;
        int                    rc = 0;

        ENTRY;

        if (data->ioc_inlbuf2 == NULL || data->ioc_inllen2 != sizeof(version))
                GOTO(out, rc = -EINVAL);

        if (data->ioc_inlbuf1 != NULL && data->ioc_inllen1 == sizeof(fid)) {
                fid = *(struct lu_fid *)data->ioc_inlbuf1;
        } else if (data->ioc_inlbuf3 != NULL &&
                   data->ioc_inllen3 == sizeof(__u64) &&
                   data->ioc_inlbuf4 != NULL &&
                   data->ioc_inllen4 == sizeof(__u64)) {
                struct ost_id ostid;

                ostid_set_seq(&ostid, *(__u64 *)data->ioc_inlbuf4);
                ostid_set_id(&ostid, *(__u64 *)data->ioc_inlbuf3);
                rc = ostid_to_fid(&fid, &ostid,
                                  ofd->ofd_lut.lut_lsd.lsd_osd_index);
                if (rc != 0)
                        GOTO(out, rc);
        } else {
                GOTO(out, rc = -EINVAL);
        }

        if (!fid_is_sane(&fid))
                GOTO(out, rc = -EINVAL);

        fo = ofd_object_find(env, ofd, &fid);
        if (IS_ERR(fo))
                GOTO(out, rc = PTR_ERR(fo));

        if (!ofd_object_exists(fo))
                GOTO(out_fo, rc = -ENOENT);

        if (lu_object_remote(&fo->ofo_obj.do_lu))
                GOTO(out_fo, rc = -EREMOTE);

        version = dt_version_get(env, ofd_object_child(fo));
        if (version == 0)
                GOTO(out_fo, rc = -EIO);

        *(dt_obj_version_t *)data->ioc_inlbuf2 = version;

        EXIT;
out_fo:
        ofd_object_put(env, fo);
out:
        return rc;
}

/**
 * Implementation of obd_ops::o_iocontrol.
 *
 * This is OFD ioctl handling function which is primary interface for
 * Lustre tools like lfs, lctl and lfsck.
 *
 * \param[in]     cmd   ioctl command
 * \param[in]     exp   OBD export of OFD
 * \param[in]     len   not used
 * \param[in,out] karg  buffer with data
 * \param[in]     uarg  not used
 *
 * \retval              0 if successful
 * \retval              negative value on error
 */
static int ofd_iocontrol(unsigned int cmd, struct obd_export *exp, int len,
                         void *karg, void __user *uarg)
{
        struct lu_env            env;
        struct ofd_device       *ofd = ofd_exp(exp);
        struct obd_device       *obd = ofd_obd(ofd);
        int                      rc;

        ENTRY;

        CDEBUG(D_IOCTL, "handling ioctl cmd %#x\n", cmd);
        rc = lu_env_init(&env, LCT_DT_THREAD);
        if (rc)
                RETURN(rc);

        switch (cmd) {
        case OBD_IOC_ABORT_RECOVERY:
                CERROR("%s: aborting recovery\n", obd->obd_name);
                obd->obd_abort_recovery = 1;
                target_stop_recovery_thread(obd);
                break;
        case OBD_IOC_SYNC:
                CDEBUG(D_RPCTRACE, "syncing ost %s\n", obd->obd_name);
                rc = dt_sync(&env, ofd->ofd_osd);
                break;
        case OBD_IOC_SET_READONLY:
                rc = dt_sync(&env, ofd->ofd_osd);
                if (rc == 0)
                        rc = dt_ro(&env, ofd->ofd_osd);
                break;
        case OBD_IOC_START_LFSCK: {
                struct obd_ioctl_data *data = karg;
                struct lfsck_start_param lsp;

                if (unlikely(data == NULL)) {
                        rc = -EINVAL;
                        break;
                }

                lsp.lsp_start = (struct lfsck_start *)(data->ioc_inlbuf1);
                lsp.lsp_index_valid = 0;
                rc = lfsck_start(&env, ofd->ofd_osd, &lsp);
                break;
        }
        case OBD_IOC_STOP_LFSCK: {
                struct obd_ioctl_data *data = karg;
                struct lfsck_stop      stop;

                stop.ls_status = LS_STOPPED;
                /* Old lfsck utils may pass NULL @stop. */
                if (data->ioc_inlbuf1 == NULL)
                        stop.ls_flags = 0;
                else
                        stop.ls_flags =
                        ((struct lfsck_stop *)(data->ioc_inlbuf1))->ls_flags;

                rc = lfsck_stop(&env, ofd->ofd_osd, &stop);
                break;
        }
        case OBD_IOC_GET_OBJ_VERSION:
                rc = ofd_ioc_get_obj_version(&env, ofd, karg);
                break;
        default:
                CERROR("%s: not supported cmd = %#x\n", obd->obd_name, cmd);
                rc = -ENOTTY;
        }

        lu_env_fini(&env);
        RETURN(rc);
}

/**
 * Implementation of obd_ops::o_precleanup.
 *
 * This function stops device activity before shutting it down. It is called
 * from a cleanup function upon forceful device cleanup. For OFD there are no
 * special actions, it just invokes target_recovery_cleanup().
 *
 * \param[in] obd       OBD device of OFD
 *
 * \retval              0
 */
static int ofd_precleanup(struct obd_device *obd)
{
        ENTRY;
        target_cleanup_recovery(obd);
        RETURN(0);
}

/**
 * Implementation of obd_ops::o_ping.
 *
 * This is OFD-specific part of OBD_PING request handling.
 * It controls Filter Modification Data (FMD) expiration each time PING is
 * received.
 *
 * \see  ofd_fmd_expire() and ofd_fmd.c for details
 *
 * \param[in] env       execution environment
 * \param[in] exp       OBD export of client
 *
 * \retval              0
 */
static int ofd_ping(const struct lu_env *env, struct obd_export *exp)
{
        ofd_fmd_expire(exp);
        return 0;
}

/**
 * Implementation of obd_ops::o_health_check.
 *
 * This function checks the OFD device health - ability to respond on
 * incoming requests. There are two health_check methods:
 * - get statfs from the OSD. It checks just responsiveness of
 *   bottom device
 * - do write attempt on bottom device to check it is fully operational and
 *   is not stuck. This is expensive method and requires special configuration
 *   option --enable-health-write while building Lustre, it is turned off
 *   by default.
 *
 * \param[in] nul       not used
 * \param[in] obd       OBD device of OFD
 *
 * \retval              0 if successful
 * \retval              negative value in case of error
 */
static int ofd_health_check(const struct lu_env *nul, struct obd_device *obd)
{
        struct ofd_device       *ofd = ofd_dev(obd->obd_lu_dev);
        struct ofd_thread_info  *info;
        struct lu_env            env;
#ifdef USE_HEALTH_CHECK_WRITE
        struct thandle          *th;
#endif
        int                      rc = 0;

        /* obd_proc_read_health pass NULL env, we need real one */
        rc = lu_env_init(&env, LCT_DT_THREAD);
        if (rc)
                RETURN(rc);

        info = ofd_info_init(&env, NULL);
        rc = dt_statfs(&env, ofd->ofd_osd, &info->fti_u.osfs);
        if (unlikely(rc))
                GOTO(out, rc);

        if (info->fti_u.osfs.os_state == OS_STATE_READONLY)
                GOTO(out, rc = -EROFS);

#ifdef USE_HEALTH_CHECK_WRITE
        OBD_ALLOC(info->fti_buf.lb_buf, PAGE_SIZE);
        if (info->fti_buf.lb_buf == NULL)
                GOTO(out, rc = -ENOMEM);

        info->fti_buf.lb_len = PAGE_SIZE;
        info->fti_off = 0;

        th = dt_trans_create(&env, ofd->ofd_osd);
        if (IS_ERR(th))
                GOTO(out, rc = PTR_ERR(th));

        rc = dt_declare_record_write(&env, ofd->ofd_health_check_file,
                                     &info->fti_buf, info->fti_off, th);
        if (rc == 0) {
                th->th_sync = 1; /* sync IO is needed */
                rc = dt_trans_start_local(&env, ofd->ofd_osd, th);
                if (rc == 0)
                        rc = dt_record_write(&env, ofd->ofd_health_check_file,
                                             &info->fti_buf, &info->fti_off,
                                             th);
        }
        dt_trans_stop(&env, ofd->ofd_osd, th);

        OBD_FREE(info->fti_buf.lb_buf, PAGE_SIZE);

        CDEBUG(D_INFO, "write 1 page synchronously for checking io rc %d\n",rc);
#endif
out:
        lu_env_fini(&env);
        return !!rc;
}

struct obd_ops ofd_obd_ops = {
        .o_owner                = THIS_MODULE,
        .o_connect              = ofd_obd_connect,
        .o_reconnect            = ofd_obd_reconnect,
        .o_disconnect           = ofd_obd_disconnect,
        .o_create               = ofd_echo_create,
        .o_statfs               = ofd_statfs,
        .o_setattr              = ofd_echo_setattr,
        .o_preprw               = ofd_preprw,
        .o_commitrw             = ofd_commitrw,
        .o_destroy              = ofd_echo_destroy,
        .o_init_export          = ofd_init_export,
        .o_destroy_export       = ofd_destroy_export,
        .o_postrecov            = ofd_obd_postrecov,
        .o_getattr              = ofd_echo_getattr,
        .o_iocontrol            = ofd_iocontrol,
        .o_precleanup           = ofd_precleanup,
        .o_ping                 = ofd_ping,
        .o_health_check         = ofd_health_check,
        .o_set_info_async       = ofd_set_info_async,
        .o_get_info             = ofd_get_info,
};