Whamcloud - gitweb
LU-6142 fld: Fix style issues for fld_request.c
[fs/lustre-release.git] / lustre / fld / fld_request.c
index 64eef6c..123bc97 100644 (file)
  *
  * You should have received a copy of the GNU General Public License
  * version 2 along with this program; If not, see
- * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * http://www.gnu.org/licenses/gpl-2.0.html
  *
  * GPL HEADER END
  */
@@ -27,7 +23,7 @@
  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2011, Whamcloud, Inc.
+ * Copyright (c) 2011, 2017, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
  * Author: Yury Umanets <umka@clusterfs.com>
  */
 
-#ifndef EXPORT_SYMTAB
-# define EXPORT_SYMTAB
-#endif
 #define DEBUG_SUBSYSTEM S_FLD
 
-#ifdef __KERNEL__
-# include <libcfs/libcfs.h>
-# include <linux/module.h>
-# include <linux/jbd.h>
-# include <asm/div64.h>
-#else /* __KERNEL__ */
-# include <liblustre.h>
-# include <libcfs/list.h>
-#endif
+#include <libcfs/libcfs.h>
+#include <linux/module.h>
+#include <linux/math64.h>
 
 #include <obd.h>
 #include <obd_class.h>
-#include <lustre_ver.h>
 #include <obd_support.h>
 #include <lprocfs_status.h>
-
-#include <dt_object.h>
-#include <md_object.h>
 #include <lustre_req_layout.h>
 #include <lustre_fld.h>
 #include <lustre_mdc.h>
 #include "fld_internal.h"
 
-/* TODO: these 3 functions are copies of flow-control code from mdc_lib.c
- * It should be common thing. The same about mdc RPC lock */
-static int fld_req_avail(struct client_obd *cli, struct mdc_cache_waiter *mcw)
-{
-        int rc;
-        ENTRY;
-        client_obd_list_lock(&cli->cl_loi_list_lock);
-        rc = cfs_list_empty(&mcw->mcw_entry);
-        client_obd_list_unlock(&cli->cl_loi_list_lock);
-        RETURN(rc);
-};
-
-static void fld_enter_request(struct client_obd *cli)
-{
-        struct mdc_cache_waiter mcw;
-        struct l_wait_info lwi = { 0 };
-
-        client_obd_list_lock(&cli->cl_loi_list_lock);
-        if (cli->cl_r_in_flight >= cli->cl_max_rpcs_in_flight) {
-                cfs_list_add_tail(&mcw.mcw_entry, &cli->cl_cache_waiters);
-                cfs_waitq_init(&mcw.mcw_waitq);
-                client_obd_list_unlock(&cli->cl_loi_list_lock);
-                l_wait_event(mcw.mcw_waitq, fld_req_avail(cli, &mcw), &lwi);
-        } else {
-                cli->cl_r_in_flight++;
-                client_obd_list_unlock(&cli->cl_loi_list_lock);
-        }
-}
-
-static void fld_exit_request(struct client_obd *cli)
-{
-        cfs_list_t *l, *tmp;
-        struct mdc_cache_waiter *mcw;
-
-        client_obd_list_lock(&cli->cl_loi_list_lock);
-        cli->cl_r_in_flight--;
-        cfs_list_for_each_safe(l, tmp, &cli->cl_cache_waiters) {
-
-                if (cli->cl_r_in_flight >= cli->cl_max_rpcs_in_flight) {
-                        /* No free request slots anymore */
-                        break;
-                }
-
-                mcw = cfs_list_entry(l, struct mdc_cache_waiter, mcw_entry);
-                cfs_list_del_init(&mcw->mcw_entry);
-                cli->cl_r_in_flight++;
-                cfs_waitq_signal(&mcw->mcw_waitq);
-        }
-        client_obd_list_unlock(&cli->cl_loi_list_lock);
-}
-
-static int fld_rrb_hash(struct lu_client_fld *fld,
-                        seqno_t seq)
+static int fld_rrb_hash(struct lu_client_fld *fld, u64 seq)
 {
-        LASSERT(fld->lcf_count > 0);
-        return do_div(seq, fld->lcf_count);
+       LASSERT(fld->lcf_count > 0);
+       return do_div(seq, fld->lcf_count);
 }
 
 static struct lu_fld_target *
-fld_rrb_scan(struct lu_client_fld *fld, seqno_t seq)
+fld_rrb_scan(struct lu_client_fld *fld, u64 seq)
 {
-        struct lu_fld_target *target;
-        int hash;
-        ENTRY;
-
-        hash = fld_rrb_hash(fld, seq);
-
-        cfs_list_for_each_entry(target, &fld->lcf_targets, ft_chain) {
-                if (target->ft_idx == hash)
-                        RETURN(target);
-        }
-
-        CERROR("%s: Can't find target by hash %d (seq "LPX64"). "
-               "Targets (%d):\n", fld->lcf_name, hash, seq,
-               fld->lcf_count);
-
-        cfs_list_for_each_entry(target, &fld->lcf_targets, ft_chain) {
-                const char *srv_name = target->ft_srv != NULL  ?
-                        target->ft_srv->lsf_name : "<null>";
-                const char *exp_name = target->ft_exp != NULL ?
-                        (char *)target->ft_exp->exp_obd->obd_uuid.uuid :
-                        "<null>";
-
-                CERROR("  exp: 0x%p (%s), srv: 0x%p (%s), idx: "LPU64"\n",
-                       target->ft_exp, exp_name, target->ft_srv,
-                       srv_name, target->ft_idx);
-        }
-
-        /*
-         * If target is not found, there is logical error anyway, so here is
-         * LBUG() to catch this situation.
-         */
-        LBUG();
-        RETURN(NULL);
+       struct lu_fld_target *target;
+       int hash;
+
+       ENTRY;
+
+       /*
+        * Because almost all of special sequence located in MDT0,
+        * it should go to index 0 directly, instead of calculating
+        * hash again, and also if other MDTs is not being connected,
+        * the fld lookup requests(for seq on MDT0) should not be
+        * blocked because of other MDTs
+        */
+       if (fid_seq_is_norm(seq))
+               hash = fld_rrb_hash(fld, seq);
+       else
+               hash = 0;
+
+again:
+       list_for_each_entry(target, &fld->lcf_targets, ft_chain) {
+               if (target->ft_idx == hash)
+                       RETURN(target);
+       }
+
+       if (hash != 0) {
+               /*
+                * It is possible the remote target(MDT) are not connected to
+                * with client yet, so we will refer this to MDT0, which should
+                * be connected during mount
+                */
+               hash = 0;
+               goto again;
+       }
+
+       CERROR("%s: Can't find target by hash %d (seq %#llx). Targets (%d):\n",
+              fld->lcf_name, hash, seq, fld->lcf_count);
+
+       list_for_each_entry(target, &fld->lcf_targets, ft_chain) {
+               const char *srv_name = target->ft_srv != NULL  ?
+                       target->ft_srv->lsf_name : "<null>";
+               const char *exp_name = target->ft_exp != NULL ?
+                       (char *)target->ft_exp->exp_obd->obd_uuid.uuid :
+                       "<null>";
+
+               CERROR("  exp: 0x%p (%s), srv: 0x%p (%s), idx: %llu\n",
+                      target->ft_exp, exp_name, target->ft_srv,
+                      srv_name, target->ft_idx);
+       }
+
+       /*
+        * If target is not found, there is logical error anyway, so here is
+        * LBUG() to catch this situation.
+        */
+       LBUG();
+       RETURN(NULL);
 }
 
 struct lu_fld_hash fld_hash[] = {
-        {
-                .fh_name = "RRB",
-                .fh_hash_func = fld_rrb_hash,
-                .fh_scan_func = fld_rrb_scan
-        },
-        {
-                0,
-        }
+       {
+               .fh_name = "RRB",
+               .fh_hash_func = fld_rrb_hash,
+               .fh_scan_func = fld_rrb_scan
+       },
+       {
+               NULL,
+       }
 };
 
 static struct lu_fld_target *
-fld_client_get_target(struct lu_client_fld *fld,
-                      seqno_t seq)
+fld_client_get_target(struct lu_client_fld *fld, u64 seq)
 {
-        struct lu_fld_target *target;
-        ENTRY;
+       struct lu_fld_target *target;
 
-        LASSERT(fld->lcf_hash != NULL);
+       ENTRY;
 
-        cfs_spin_lock(&fld->lcf_lock);
-        target = fld->lcf_hash->fh_scan_func(fld, seq);
-        cfs_spin_unlock(&fld->lcf_lock);
+       LASSERT(fld->lcf_hash != NULL);
 
-        if (target != NULL) {
-                CDEBUG(D_INFO, "%s: Found target (idx "LPU64
-                       ") by seq "LPX64"\n", fld->lcf_name,
-                       target->ft_idx, seq);
-        }
+       spin_lock(&fld->lcf_lock);
+       target = fld->lcf_hash->fh_scan_func(fld, seq);
+       spin_unlock(&fld->lcf_lock);
 
-        RETURN(target);
+       if (target) {
+               CDEBUG(D_INFO, "%s: Found target (idx %llu) by seq %#llx\n",
+                      fld->lcf_name, target->ft_idx, seq);
+       }
+
+       RETURN(target);
 }
 
 /*
@@ -202,319 +153,404 @@ fld_client_get_target(struct lu_client_fld *fld,
  * of FLD module.
  */
 int fld_client_add_target(struct lu_client_fld *fld,
-                          struct lu_fld_target *tar)
+                         struct lu_fld_target *tar)
 {
-        const char *name = fld_target_name(tar);
-        struct lu_fld_target *target, *tmp;
-        ENTRY;
-
-        LASSERT(tar != NULL);
-        LASSERT(name != NULL);
-        LASSERT(tar->ft_srv != NULL || tar->ft_exp != NULL);
-
-        if (fld->lcf_flags != LUSTRE_FLD_INIT) {
-                CERROR("%s: Attempt to add target %s (idx "LPU64") "
-                       "on fly - skip it\n", fld->lcf_name, name,
-                       tar->ft_idx);
-                RETURN(0);
-        } else {
-                CDEBUG(D_INFO, "%s: Adding target %s (idx "
-                       LPU64")\n", fld->lcf_name, name, tar->ft_idx);
-        }
-
-        OBD_ALLOC_PTR(target);
-        if (target == NULL)
-                RETURN(-ENOMEM);
-
-        cfs_spin_lock(&fld->lcf_lock);
-        cfs_list_for_each_entry(tmp, &fld->lcf_targets, ft_chain) {
-                if (tmp->ft_idx == tar->ft_idx) {
-                        cfs_spin_unlock(&fld->lcf_lock);
-                        OBD_FREE_PTR(target);
-                        CERROR("Target %s exists in FLD and known as %s:#"LPU64"\n",
-                               name, fld_target_name(tmp), tmp->ft_idx);
-                        RETURN(-EEXIST);
-                }
-        }
-
-        target->ft_exp = tar->ft_exp;
-        if (target->ft_exp != NULL)
-                class_export_get(target->ft_exp);
-        target->ft_srv = tar->ft_srv;
-        target->ft_idx = tar->ft_idx;
-
-        cfs_list_add_tail(&target->ft_chain,
-                          &fld->lcf_targets);
-
-        fld->lcf_count++;
-        cfs_spin_unlock(&fld->lcf_lock);
-
-        RETURN(0);
+       const char *name;
+       struct lu_fld_target *target, *tmp;
+
+       ENTRY;
+
+       LASSERT(tar != NULL);
+       name = fld_target_name(tar);
+       LASSERT(name != NULL);
+       LASSERT(tar->ft_srv != NULL || tar->ft_exp != NULL);
+
+       CDEBUG(D_INFO, "%s: Adding target %s (idx %llu)\n", fld->lcf_name,
+              name, tar->ft_idx);
+
+       OBD_ALLOC_PTR(target);
+       if (!target)
+               RETURN(-ENOMEM);
+
+       spin_lock(&fld->lcf_lock);
+       list_for_each_entry(tmp, &fld->lcf_targets, ft_chain) {
+               if (tmp->ft_idx == tar->ft_idx) {
+                       spin_unlock(&fld->lcf_lock);
+                       OBD_FREE_PTR(target);
+                       CERROR("Target %s exists in FLD and known as %s:#%llu\n",
+                              name, fld_target_name(tmp), tmp->ft_idx);
+                       RETURN(-EEXIST);
+               }
+       }
+
+       target->ft_exp = tar->ft_exp;
+       if (target->ft_exp)
+               class_export_get(target->ft_exp);
+       target->ft_srv = tar->ft_srv;
+       target->ft_idx = tar->ft_idx;
+
+       list_add_tail(&target->ft_chain, &fld->lcf_targets);
+
+       fld->lcf_count++;
+       spin_unlock(&fld->lcf_lock);
+
+       RETURN(0);
 }
 EXPORT_SYMBOL(fld_client_add_target);
 
 /* Remove export from FLD */
-int fld_client_del_target(struct lu_client_fld *fld,
-                          __u64 idx)
+int fld_client_del_target(struct lu_client_fld *fld, u64 idx)
 {
-        struct lu_fld_target *target, *tmp;
-        ENTRY;
-
-        cfs_spin_lock(&fld->lcf_lock);
-        cfs_list_for_each_entry_safe(target, tmp,
-                                     &fld->lcf_targets, ft_chain) {
-                if (target->ft_idx == idx) {
-                        fld->lcf_count--;
-                        cfs_list_del(&target->ft_chain);
-                        cfs_spin_unlock(&fld->lcf_lock);
-
-                        if (target->ft_exp != NULL)
-                                class_export_put(target->ft_exp);
-
-                        OBD_FREE_PTR(target);
-                        RETURN(0);
-                }
-        }
-        cfs_spin_unlock(&fld->lcf_lock);
-        RETURN(-ENOENT);
+       struct lu_fld_target *target, *tmp;
+
+       ENTRY;
+
+       spin_lock(&fld->lcf_lock);
+       list_for_each_entry_safe(target, tmp, &fld->lcf_targets, ft_chain) {
+               if (target->ft_idx == idx) {
+                       fld->lcf_count--;
+                       list_del(&target->ft_chain);
+                       spin_unlock(&fld->lcf_lock);
+
+                       if (target->ft_exp)
+                               class_export_put(target->ft_exp);
+
+                       OBD_FREE_PTR(target);
+                       RETURN(0);
+               }
+       }
+       spin_unlock(&fld->lcf_lock);
+       RETURN(-ENOENT);
 }
-EXPORT_SYMBOL(fld_client_del_target);
 
-#ifdef LPROCFS
-static int fld_client_proc_init(struct lu_client_fld *fld)
-{
-        int rc;
-        ENTRY;
-
-        fld->lcf_proc_dir = lprocfs_register(fld->lcf_name,
-                                             fld_type_proc_dir,
-                                             NULL, NULL);
-
-        if (IS_ERR(fld->lcf_proc_dir)) {
-                CERROR("%s: LProcFS failed in fld-init\n",
-                       fld->lcf_name);
-                rc = PTR_ERR(fld->lcf_proc_dir);
-                RETURN(rc);
-        }
-
-        rc = lprocfs_add_vars(fld->lcf_proc_dir,
-                              fld_client_proc_list, fld);
-        if (rc) {
-                CERROR("%s: Can't init FLD proc, rc %d\n",
-                       fld->lcf_name, rc);
-                GOTO(out_cleanup, rc);
-        }
-
-        RETURN(0);
-
-out_cleanup:
-        fld_client_proc_fini(fld);
-        return rc;
-}
+struct dentry *fld_debugfs_dir;
 
-void fld_client_proc_fini(struct lu_client_fld *fld)
+static int fld_client_debugfs_init(struct lu_client_fld *fld)
 {
-        ENTRY;
-        if (fld->lcf_proc_dir) {
-                if (!IS_ERR(fld->lcf_proc_dir))
-                        lprocfs_remove(&fld->lcf_proc_dir);
-                fld->lcf_proc_dir = NULL;
-        }
-        EXIT;
-}
-#else
-static int fld_client_proc_init(struct lu_client_fld *fld)
-{
-        return 0;
+       int rc;
+
+       ENTRY;
+       fld->lcf_debugfs_entry = ldebugfs_register(fld->lcf_name,
+                                                  fld_debugfs_dir,
+                                                  fld_client_debugfs_list,
+                                                  fld);
+       if (IS_ERR_OR_NULL(fld->lcf_debugfs_entry)) {
+               CERROR("%s: LdebugFS failed in fld-init\n", fld->lcf_name);
+               rc = fld->lcf_debugfs_entry ? PTR_ERR(fld->lcf_debugfs_entry)
+                                           : -ENOMEM;
+               fld->lcf_debugfs_entry = NULL;
+               RETURN(rc);
+       }
+
+       return 0;
 }
 
-void fld_client_proc_fini(struct lu_client_fld *fld)
+void fld_client_debugfs_fini(struct lu_client_fld *fld)
 {
-        return;
+       if (!IS_ERR_OR_NULL(fld->lcf_debugfs_entry))
+               ldebugfs_remove(&fld->lcf_debugfs_entry);
 }
-#endif
-
-EXPORT_SYMBOL(fld_client_proc_fini);
+EXPORT_SYMBOL(fld_client_debugfs_fini);
 
 static inline int hash_is_sane(int hash)
 {
-        return (hash >= 0 && hash < ARRAY_SIZE(fld_hash));
+       return (hash >= 0 && hash < ARRAY_SIZE(fld_hash));
 }
 
 int fld_client_init(struct lu_client_fld *fld,
-                    const char *prefix, int hash)
+                   const char *prefix, int hash)
 {
-        int cache_size, cache_threshold;
-        int rc;
-        ENTRY;
-
-        LASSERT(fld != NULL);
-
-        snprintf(fld->lcf_name, sizeof(fld->lcf_name),
-                 "cli-%s", prefix);
-
-        if (!hash_is_sane(hash)) {
-                CERROR("%s: Wrong hash function %#x\n",
-                       fld->lcf_name, hash);
-                RETURN(-EINVAL);
-        }
-
-        fld->lcf_count = 0;
-        cfs_spin_lock_init(&fld->lcf_lock);
-        fld->lcf_hash = &fld_hash[hash];
-        fld->lcf_flags = LUSTRE_FLD_INIT;
-        CFS_INIT_LIST_HEAD(&fld->lcf_targets);
-
-        cache_size = FLD_CLIENT_CACHE_SIZE /
-                sizeof(struct fld_cache_entry);
-
-        cache_threshold = cache_size *
-                FLD_CLIENT_CACHE_THRESHOLD / 100;
-
-        fld->lcf_cache = fld_cache_init(fld->lcf_name,
-                                        cache_size, cache_threshold);
-        if (IS_ERR(fld->lcf_cache)) {
-                rc = PTR_ERR(fld->lcf_cache);
-                fld->lcf_cache = NULL;
-                GOTO(out, rc);
-        }
-
-        rc = fld_client_proc_init(fld);
-        if (rc)
-                GOTO(out, rc);
-        EXIT;
+       int cache_size, cache_threshold;
+       int rc;
+
+       ENTRY;
+       snprintf(fld->lcf_name, sizeof(fld->lcf_name),
+                "cli-%s", prefix);
+
+       if (!hash_is_sane(hash)) {
+               CERROR("%s: Wrong hash function %#x\n",
+                      fld->lcf_name, hash);
+               RETURN(-EINVAL);
+       }
+
+       fld->lcf_count = 0;
+       spin_lock_init(&fld->lcf_lock);
+       fld->lcf_hash = &fld_hash[hash];
+       INIT_LIST_HEAD(&fld->lcf_targets);
+
+       cache_size = FLD_CLIENT_CACHE_SIZE /
+               sizeof(struct fld_cache_entry);
+
+       cache_threshold = cache_size *
+               FLD_CLIENT_CACHE_THRESHOLD / 100;
+
+       fld->lcf_cache = fld_cache_init(fld->lcf_name,
+                                       cache_size, cache_threshold);
+       if (IS_ERR(fld->lcf_cache)) {
+               rc = PTR_ERR(fld->lcf_cache);
+               fld->lcf_cache = NULL;
+               GOTO(out, rc);
+       }
+
+       rc = fld_client_debugfs_init(fld);
+       if (rc)
+               GOTO(out, rc);
+       EXIT;
 out:
-        if (rc)
-                fld_client_fini(fld);
-        else
-                CDEBUG(D_INFO, "%s: Using \"%s\" hash\n",
-                       fld->lcf_name, fld->lcf_hash->fh_name);
-        return rc;
+       if (rc)
+               fld_client_fini(fld);
+       else
+               CDEBUG(D_INFO, "%s: Using \"%s\" hash\n",
+                      fld->lcf_name, fld->lcf_hash->fh_name);
+       return rc;
 }
 EXPORT_SYMBOL(fld_client_init);
 
 void fld_client_fini(struct lu_client_fld *fld)
 {
-        struct lu_fld_target *target, *tmp;
-        ENTRY;
-
-        cfs_spin_lock(&fld->lcf_lock);
-        cfs_list_for_each_entry_safe(target, tmp,
-                                     &fld->lcf_targets, ft_chain) {
-                fld->lcf_count--;
-                cfs_list_del(&target->ft_chain);
-                if (target->ft_exp != NULL)
-                        class_export_put(target->ft_exp);
-                OBD_FREE_PTR(target);
-        }
-        cfs_spin_unlock(&fld->lcf_lock);
-
-        if (fld->lcf_cache != NULL) {
-                if (!IS_ERR(fld->lcf_cache))
-                        fld_cache_fini(fld->lcf_cache);
-                fld->lcf_cache = NULL;
-        }
-
-        EXIT;
+       struct lu_fld_target *target, *tmp;
+
+       ENTRY;
+
+       spin_lock(&fld->lcf_lock);
+       list_for_each_entry_safe(target, tmp, &fld->lcf_targets, ft_chain) {
+               fld->lcf_count--;
+               list_del(&target->ft_chain);
+               if (target->ft_exp)
+                       class_export_put(target->ft_exp);
+               OBD_FREE_PTR(target);
+       }
+       spin_unlock(&fld->lcf_lock);
+
+       if (fld->lcf_cache) {
+               if (!IS_ERR(fld->lcf_cache))
+                       fld_cache_fini(fld->lcf_cache);
+               fld->lcf_cache = NULL;
+       }
+
+       EXIT;
 }
 EXPORT_SYMBOL(fld_client_fini);
 
 int fld_client_rpc(struct obd_export *exp,
-                   struct lu_seq_range *range, __u32 fld_op)
+                  struct lu_seq_range *range, u32 fld_op,
+                  struct ptlrpc_request **reqp)
 {
-        struct ptlrpc_request *req;
-        struct lu_seq_range      *prange;
-        __u32                 *op;
-        int                    rc;
-        ENTRY;
-
-        LASSERT(exp != NULL);
-
-        req = ptlrpc_request_alloc_pack(class_exp2cliimp(exp), &RQF_FLD_QUERY,
-                                        LUSTRE_MDS_VERSION, FLD_QUERY);
-        if (req == NULL)
-                RETURN(-ENOMEM);
-
-        op = req_capsule_client_get(&req->rq_pill, &RMF_FLD_OPC);
-        *op = fld_op;
-
-        prange = req_capsule_client_get(&req->rq_pill, &RMF_FLD_MDFLD);
-        *prange = *range;
-
-        ptlrpc_request_set_replen(req);
-        req->rq_request_portal = FLD_REQUEST_PORTAL;
-        ptlrpc_at_set_req_timeout(req);
-
-        if (fld_op != FLD_LOOKUP)
-                mdc_get_rpc_lock(exp->exp_obd->u.cli.cl_rpc_lock, NULL);
-        fld_enter_request(&exp->exp_obd->u.cli);
-        rc = ptlrpc_queue_wait(req);
-        fld_exit_request(&exp->exp_obd->u.cli);
-        if (fld_op != FLD_LOOKUP)
-                mdc_put_rpc_lock(exp->exp_obd->u.cli.cl_rpc_lock, NULL);
-        if (rc)
-                GOTO(out_req, rc);
-
-        prange = req_capsule_server_get(&req->rq_pill, &RMF_FLD_MDFLD);
-        if (prange == NULL)
-                GOTO(out_req, rc = -EFAULT);
-        *range = *prange;
-        EXIT;
+       struct ptlrpc_request *req = NULL;
+       struct lu_seq_range *prange;
+       u32 *op;
+       int rc = 0;
+       struct obd_import *imp;
+
+       ENTRY;
+
+       LASSERT(exp != NULL);
+
+again:
+       imp = class_exp2cliimp(exp);
+       switch (fld_op) {
+       case FLD_QUERY:
+               req = ptlrpc_request_alloc_pack(imp, &RQF_FLD_QUERY,
+                                               LUSTRE_MDS_VERSION, FLD_QUERY);
+               if (!req)
+                       RETURN(-ENOMEM);
+
+               /*
+                * XXX: only needed when talking to old server(< 2.6), it should
+                * be removed when < 2.6 server is not supported
+                */
+               op = req_capsule_client_get(&req->rq_pill, &RMF_FLD_OPC);
+               *op = FLD_LOOKUP;
+
+               /*
+                * For MDS_MDS seq lookup, it will always use LWP connection,
+                * but LWP will be evicted after restart, so cause the error.
+                * so we will set no_delay for seq lookup request, once the
+                * request fails because of the eviction. always retry here
+                */
+               if (imp->imp_connect_flags_orig & OBD_CONNECT_MDS_MDS) {
+                       req->rq_allow_replay = 1;
+                       req->rq_no_delay = 1;
+               }
+               break;
+       case FLD_READ:
+               req = ptlrpc_request_alloc_pack(imp, &RQF_FLD_READ,
+                                               LUSTRE_MDS_VERSION, FLD_READ);
+               if (!req)
+                       RETURN(-ENOMEM);
+
+               req_capsule_set_size(&req->rq_pill, &RMF_GENERIC_DATA,
+                                    RCL_SERVER, PAGE_SIZE);
+               break;
+       default:
+               rc = -EINVAL;
+               break;
+       }
+
+       if (rc != 0)
+               RETURN(rc);
+
+       prange = req_capsule_client_get(&req->rq_pill, &RMF_FLD_MDFLD);
+       *prange = *range;
+       ptlrpc_request_set_replen(req);
+       req->rq_request_portal = FLD_REQUEST_PORTAL;
+       req->rq_reply_portal = MDC_REPLY_PORTAL;
+       ptlrpc_at_set_req_timeout(req);
+
+       obd_get_request_slot(&exp->exp_obd->u.cli);
+       rc = ptlrpc_queue_wait(req);
+       obd_put_request_slot(&exp->exp_obd->u.cli);
+
+       if (rc == -ENOENT) {
+               /* Don't loop forever on non-existing FID sequences. */
+               GOTO(out_req, rc);
+       }
+
+       if (rc != 0) {
+               if (imp->imp_state != LUSTRE_IMP_CLOSED &&
+                   !imp->imp_deactive &&
+                   imp->imp_connect_flags_orig & OBD_CONNECT_MDS_MDS &&
+                   OCD_HAS_FLAG(&imp->imp_connect_data, LIGHTWEIGHT) &&
+                   rc != -ENOTSUPP) {
+                       /*
+                        * Since LWP is not replayable, so it will keep
+                        * trying unless umount happens or the remote
+                        * target does not support the operation, otherwise
+                        * it would cause unecessary failure of the
+                        * application.
+                        */
+                       ptlrpc_req_finished(req);
+                       rc = 0;
+                       goto again;
+               }
+               GOTO(out_req, rc);
+       }
+
+       if (fld_op == FLD_QUERY) {
+               prange = req_capsule_server_get(&req->rq_pill,
+                                               &RMF_FLD_MDFLD);
+               if (!prange)
+                       GOTO(out_req, rc = -EFAULT);
+               *range = *prange;
+       }
+
+       EXIT;
 out_req:
-        ptlrpc_req_finished(req);
-        return rc;
+       if (rc != 0 || !reqp) {
+               ptlrpc_req_finished(req);
+               req = NULL;
+       }
+
+       if (reqp)
+               *reqp = req;
+
+       return rc;
 }
 
-int fld_client_lookup(struct lu_client_fld *fld, seqno_t seq, mdsno_t *mds,
-                      __u32 flags, const struct lu_env *env)
+int fld_client_lookup(struct lu_client_fld *fld, u64 seq, u32 *mds,
+                     u32 flags, const struct lu_env *env)
 {
-        struct lu_seq_range res;
-        struct lu_fld_target *target;
-        int rc;
-        ENTRY;
-
-        fld->lcf_flags |= LUSTRE_FLD_RUN;
-
-        rc = fld_cache_lookup(fld->lcf_cache, seq, &res);
-        if (rc == 0) {
-                *mds = res.lsr_index;
-                RETURN(0);
-        }
-
-        /* Can not find it in the cache */
-        target = fld_client_get_target(fld, seq);
-        LASSERT(target != NULL);
-
-        CDEBUG(D_INFO, "%s: Lookup fld entry (seq: "LPX64") on "
-               "target %s (idx "LPU64")\n", fld->lcf_name, seq,
-               fld_target_name(target), target->ft_idx);
-
-        res.lsr_start = seq;
-        res.lsr_flags = flags;
-#ifdef __KERNEL__
-        if (target->ft_srv != NULL) {
-                LASSERT(env != NULL);
-                rc = fld_server_lookup(target->ft_srv,
-                                       env, seq, &res);
-        } else {
-#endif
-                rc = fld_client_rpc(target->ft_exp,
-                                    &res, FLD_LOOKUP);
-#ifdef __KERNEL__
-        }
-#endif
-
-        if (rc == 0) {
-                *mds = res.lsr_index;
-
-                fld_cache_insert(fld->lcf_cache, &res);
-        }
-        RETURN(rc);
+       struct lu_seq_range res = { 0 };
+       struct lu_fld_target *target;
+       struct lu_fld_target *origin;
+       int rc;
+
+       ENTRY;
+
+       rc = fld_cache_lookup(fld->lcf_cache, seq, &res);
+       if (rc == 0) {
+               *mds = res.lsr_index;
+               RETURN(0);
+       }
+
+       /* Can not find it in the cache */
+       target = fld_client_get_target(fld, seq);
+       LASSERT(target != NULL);
+       origin = target;
+again:
+       CDEBUG(D_INFO, "%s: Lookup fld entry (seq: %#llx) on target %s (idx %llu)\n",
+              fld->lcf_name, seq, fld_target_name(target), target->ft_idx);
+
+       res.lsr_start = seq;
+       fld_range_set_type(&res, flags);
+
+#ifdef HAVE_SERVER_SUPPORT
+       if (target->ft_srv) {
+               LASSERT(env != NULL);
+               rc = fld_server_lookup(env, target->ft_srv, seq, &res);
+       } else
+#endif /* HAVE_SERVER_SUPPORT */
+       {
+               rc = fld_client_rpc(target->ft_exp, &res, FLD_QUERY, NULL);
+       }
+
+       if (rc == -ESHUTDOWN) {
+               /*
+                * If fld lookup failed because the target has been shutdown,
+                * then try next target in the list, until trying all targets
+                * or fld lookup succeeds
+                */
+               spin_lock(&fld->lcf_lock);
+               /*
+                * If the next entry in the list is the head of the list,
+                * move to the next entry after the head and retrieve
+                * the target. Else retreive the next target entry.
+                */
+               if (target->ft_chain.next == &fld->lcf_targets)
+                       target = list_entry(target->ft_chain.next->next,
+                                           struct lu_fld_target, ft_chain);
+               else
+                       target = list_entry(target->ft_chain.next,
+                                                struct lu_fld_target,
+                                                ft_chain);
+               spin_unlock(&fld->lcf_lock);
+               if (target != origin)
+                       goto again;
+       }
+       if (rc == 0) {
+               *mds = res.lsr_index;
+               fld_cache_insert(fld->lcf_cache, &res);
+       }
+
+       RETURN(rc);
 }
 EXPORT_SYMBOL(fld_client_lookup);
 
 void fld_client_flush(struct lu_client_fld *fld)
 {
-        fld_cache_flush(fld->lcf_cache);
+       fld_cache_flush(fld->lcf_cache);
+}
+
+static int __init fld_init(void)
+{
+#ifdef HAVE_SERVER_SUPPORT
+       int rc;
+
+       rc = fld_server_mod_init();
+       if (rc)
+               return rc;
+#endif /* HAVE_SERVER_SUPPORT */
+
+       fld_debugfs_dir = ldebugfs_register(LUSTRE_FLD_NAME,
+                                           debugfs_lustre_root,
+                                           NULL, NULL);
+       return PTR_ERR_OR_ZERO(fld_debugfs_dir);
 }
-EXPORT_SYMBOL(fld_client_flush);
+
+static void __exit fld_exit(void)
+{
+#ifdef HAVE_SERVER_SUPPORT
+       fld_server_mod_exit();
+#endif /* HAVE_SERVER_SUPPORT */
+
+       if (!IS_ERR_OR_NULL(fld_debugfs_dir))
+               ldebugfs_remove(&fld_debugfs_dir);
+}
+
+MODULE_AUTHOR("OpenSFS, Inc. <http://www.lustre.org/>");
+MODULE_DESCRIPTION("Lustre FID Location Database");
+MODULE_VERSION(LUSTRE_VERSION_STRING);
+MODULE_LICENSE("GPL");
+
+module_init(fld_init);
+module_exit(fld_exit);