Whamcloud - gitweb
LU-6158 mdt: always shrink_capsule in getxattr_all
[fs/lustre-release.git] / lustre / fld / fld_index.c
index 2a8d314..efff9fe 100644 (file)
@@ -27,7 +27,7 @@
  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2011, 2012, Whamcloud, Inc.
+ * Copyright (c) 2011, 2014, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
 
 #define DEBUG_SUBSYSTEM S_FLD
 
-#ifdef __KERNEL__
-# include <libcfs/libcfs.h>
-# include <linux/module.h>
-# include <linux/jbd.h>
-#else /* __KERNEL__ */
-# include <liblustre.h>
-#endif
-
-#include <obd.h>
-#include <obd_class.h>
-#include <lustre_ver.h>
+#include <libcfs/libcfs.h>
+#include <linux/module.h>
 #include <obd_support.h>
-#include <lprocfs_status.h>
-
 #include <dt_object.h>
-#include <md_object.h>
-#include <lustre_mdc.h>
 #include <lustre_fid.h>
 #include <lustre_fld.h>
 #include "fld_internal.h"
 
-const char fld_index_name[] = "fld";
+static const char fld_index_name[] = "fld";
 
 static const struct lu_seq_range IGIF_FLD_RANGE = {
-        .lsr_start = 1,
-        .lsr_end   = FID_SEQ_IDIF,
-        .lsr_index   = 0,
-        .lsr_flags  = LU_SEQ_RANGE_MDT
+       .lsr_start = FID_SEQ_IGIF,
+       .lsr_end   = FID_SEQ_IGIF_MAX + 1,
+       .lsr_index = 0,
+       .lsr_flags = LU_SEQ_RANGE_MDT
 };
 
-const struct dt_index_features fld_index_features = {
-       .dif_flags       = DT_IND_UPDATE | DT_IND_RANGE,
-        .dif_keysize_min = sizeof(seqno_t),
-        .dif_keysize_max = sizeof(seqno_t),
-        .dif_recsize_min = sizeof(struct lu_seq_range),
-        .dif_recsize_max = sizeof(struct lu_seq_range),
-        .dif_ptrsize     = 4
+static const struct lu_seq_range DOT_LUSTRE_FLD_RANGE = {
+       .lsr_start = FID_SEQ_DOT_LUSTRE,
+       .lsr_end   = FID_SEQ_DOT_LUSTRE + 1,
+       .lsr_index = 0,
+       .lsr_flags = LU_SEQ_RANGE_MDT
 };
 
-extern struct lu_context_key fld_thread_key;
-
-static struct dt_key *fld_key(const struct lu_env *env, const seqno_t seq)
-{
-        struct fld_thread_info *info;
-        ENTRY;
-
-        info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
-        LASSERT(info != NULL);
-
-        info->fti_key = cpu_to_be64(seq);
-        RETURN((void *)&info->fti_key);
-}
-
-static struct dt_rec *fld_rec(const struct lu_env *env,
-                              const struct lu_seq_range *range)
-{
-        struct fld_thread_info *info;
-        struct lu_seq_range *rec;
-        ENTRY;
-
-        info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
-        LASSERT(info != NULL);
-        rec = &info->fti_rec;
-
-        range_cpu_to_be(rec, range);
-        RETURN((void *)rec);
-}
-
-struct thandle *fld_trans_create(struct lu_server_fld *fld,
-                                const struct lu_env *env)
-{
-        struct dt_device *dt_dev;
-
-        dt_dev = lu2dt_dev(fld->lsf_obj->do_lu.lo_dev);
-
-        return dt_dev->dd_ops->dt_trans_create(env, dt_dev);
-}
-
-int fld_trans_start(struct lu_server_fld *fld,
-                                const struct lu_env *env, struct thandle *th)
-{
-        struct dt_device *dt_dev;
-
-        dt_dev = lu2dt_dev(fld->lsf_obj->do_lu.lo_dev);
-
-        return dt_dev->dd_ops->dt_trans_start(env, dt_dev, th);
-}
+static const struct lu_seq_range ROOT_FLD_RANGE = {
+       .lsr_start = FID_SEQ_ROOT,
+       .lsr_end   = FID_SEQ_ROOT + 1,
+       .lsr_index = 0,
+       .lsr_flags = LU_SEQ_RANGE_MDT
+};
 
-void fld_trans_stop(struct lu_server_fld *fld,
-                    const struct lu_env *env, struct thandle* th)
-{
-        struct dt_device *dt_dev;
+static const struct dt_index_features fld_index_features = {
+       .dif_flags       = DT_IND_UPDATE,
+       .dif_keysize_min = sizeof(u64),
+       .dif_keysize_max = sizeof(u64),
+       .dif_recsize_min = sizeof(struct lu_seq_range),
+       .dif_recsize_max = sizeof(struct lu_seq_range),
+       .dif_ptrsize     = 4
+};
 
-        dt_dev = lu2dt_dev(fld->lsf_obj->do_lu.lo_dev);
-        dt_dev->dd_ops->dt_trans_stop(env, th);
-}
+extern struct lu_context_key fld_thread_key;
 
-int fld_declare_index_create(struct lu_server_fld *fld,
-                             const struct lu_env *env,
-                             const struct lu_seq_range *range,
-                             struct thandle *th)
+int fld_declare_index_create(const struct lu_env *env,
+                            struct lu_server_fld *fld,
+                            const struct lu_seq_range *new_range,
+                            struct thandle *th)
 {
-        struct dt_object *dt_obj = fld->lsf_obj;
-        seqno_t start;
-        int rc;
-
-        ENTRY;
+       struct lu_seq_range     *tmp;
+       struct lu_seq_range     *range;
+       struct fld_thread_info  *info;
+       int                     rc = 0;
+
+       ENTRY;
+
+       info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
+       range = &info->fti_lrange;
+       tmp = &info->fti_irange;
+       memset(range, 0, sizeof(*range));
+
+       rc = fld_index_lookup(env, fld, new_range->lsr_start, range);
+       if (rc == 0) {
+               /* In case of duplicate entry, the location must be same */
+               LASSERT((range_compare_loc(new_range, range) == 0));
+               GOTO(out, rc = -EEXIST);
+       }
 
-       if (fld->lsf_no_range_lookup) {
-               /* Stub for underlying FS which can't lookup ranges */
-               return 0;
+       if (rc != -ENOENT) {
+               CERROR("%s: lookup range "DRANGE" error: rc = %d\n",
+                       fld->lsf_name, PRANGE(range), rc);
+               GOTO(out, rc);
        }
 
-        start = range->lsr_start;
-        LASSERT(range_is_sane(range));
+       /* Check for merge case, since the fld entry can only be increamental,
+        * so we will only check whether it can be merged from the left. */
+       if (new_range->lsr_start == range->lsr_end && range->lsr_end != 0 &&
+           range_compare_loc(new_range, range) == 0) {
+               range_cpu_to_be(tmp, range);
+               rc = dt_declare_delete(env, fld->lsf_obj,
+                                      (struct dt_key *)&tmp->lsr_start, th);
+               if (rc) {
+                       CERROR("%s: declare record "DRANGE" failed: rc = %d\n",
+                              fld->lsf_name, PRANGE(range), rc);
+                       GOTO(out, rc);
+               }
+               *tmp = *new_range;
+               tmp->lsr_start = range->lsr_start;
+       } else {
+               *tmp = *new_range;
+       }
 
-        rc = dt_obj->do_index_ops->dio_declare_insert(env, dt_obj,
-                                                      fld_rec(env, range),
-                                                      fld_key(env, start), th);
-        RETURN(rc);
+       range_cpu_to_be(tmp, tmp);
+       rc = dt_declare_insert(env, fld->lsf_obj, (struct dt_rec *)tmp,
+                              (struct dt_key *)&tmp->lsr_start, th);
+out:
+       RETURN(rc);
 }
 
 /**
@@ -172,71 +147,76 @@ int fld_declare_index_create(struct lu_server_fld *fld,
  *
  *      \retval  0  success
  *      \retval  -ve error
- */
-
-int fld_index_create(struct lu_server_fld *fld,
-                     const struct lu_env *env,
-                     const struct lu_seq_range *range,
-                     struct thandle *th)
-{
-        struct dt_object *dt_obj = fld->lsf_obj;
-        seqno_t start;
-        int rc;
-
-        ENTRY;
-
-       if (fld->lsf_no_range_lookup) {
-               /* Stub for underlying FS which can't lookup ranges */
-               if (range->lsr_index != 0) {
-                       CERROR("%s: FLD backend does not support range"
-                              "lookups, so DNE and FIDs-on-OST are not"
-                              "supported in this configuration\n",
-                              fld->lsf_name);
-                       return -EINVAL;
-               }
-       }
-
-        start = range->lsr_start;
-        LASSERT(range_is_sane(range));
-
-        rc = dt_obj->do_index_ops->dio_insert(env, dt_obj,
-                                              fld_rec(env, range),
-                                              fld_key(env, start),
-                                              th, BYPASS_CAPA, 1);
-
-        CDEBUG(D_INFO, "%s: insert given range : "DRANGE" rc = %d\n",
-               fld->lsf_name, PRANGE(range), rc);
-        RETURN(rc);
-}
-
-/**
- * delete range in fld store.
  *
- *      \param  range range to be deleted
- *      \param  th     transaction
+ * The whole fld index insertion is protected by seq->lss_mutex (see
+ * seq_server_alloc_super), i.e. only one thread will access fldb each
+ * time, so we do not need worry the fld file and cache will being
+ * changed between declare and create.
+ * Because the fld entry can only be increamental, so we will only check
+ * whether it can be merged from the left.
  *
- *      \retval  0  success
- *      \retval  -ve error
- */
-
-int fld_index_delete(struct lu_server_fld *fld,
-                     const struct lu_env *env,
-                     struct lu_seq_range *range,
-                     struct thandle   *th)
+ * Caller must hold fld->lsf_lock
+ **/
+int fld_index_create(const struct lu_env *env, struct lu_server_fld *fld,
+                    const struct lu_seq_range *new_range, struct thandle *th)
 {
-        struct dt_object *dt_obj = fld->lsf_obj;
-        seqno_t seq = range->lsr_start;
-        int rc;
-
-        ENTRY;
+       struct lu_seq_range     *range;
+       struct lu_seq_range     *tmp;
+       struct fld_thread_info  *info;
+       int                     rc = 0;
+       int                     deleted = 0;
+       struct fld_cache_entry  *flde;
+       ENTRY;
+
+       info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
+
+       LASSERT(mutex_is_locked(&fld->lsf_lock));
+
+       range = &info->fti_lrange;
+       memset(range, 0, sizeof(*range));
+       tmp = &info->fti_irange;
+       rc = fld_index_lookup(env, fld, new_range->lsr_start, range);
+       if (rc != -ENOENT) {
+               rc = rc == 0 ? -EEXIST : rc;
+               GOTO(out, rc);
+       }
 
-        rc = dt_obj->do_index_ops->dio_delete(env, dt_obj, fld_key(env, seq),
-                                              th, BYPASS_CAPA);
+       if (new_range->lsr_start == range->lsr_end && range->lsr_end != 0 &&
+           range_compare_loc(new_range, range) == 0) {
+               range_cpu_to_be(tmp, range);
+               rc = dt_delete(env, fld->lsf_obj,
+                              (struct dt_key *)&tmp->lsr_start, th);
+               if (rc != 0)
+                       GOTO(out, rc);
+               *tmp = *new_range;
+               tmp->lsr_start = range->lsr_start;
+               deleted = 1;
+       } else {
+               *tmp = *new_range;
+       }
 
-        CDEBUG(D_INFO, "%s: delete given range : "DRANGE" rc = %d\n",
-               fld->lsf_name, PRANGE(range), rc);
+       range_cpu_to_be(tmp, tmp);
+       rc = dt_insert(env, fld->lsf_obj, (struct dt_rec *)tmp,
+                      (struct dt_key *)&tmp->lsr_start, th, 1);
+       if (rc != 0) {
+               CERROR("%s: insert range "DRANGE" failed: rc = %d\n",
+                      fld->lsf_name, PRANGE(new_range), rc);
+               GOTO(out, rc);
+       }
 
-        RETURN(rc);
+       flde = fld_cache_entry_create(new_range);
+       if (IS_ERR(flde))
+               GOTO(out, rc = PTR_ERR(flde));
+
+       write_lock(&fld->lsf_cache->fci_lock);
+       if (deleted)
+               fld_cache_delete_nolock(fld->lsf_cache, new_range);
+       rc = fld_cache_insert_nolock(fld->lsf_cache, flde);
+       write_unlock(&fld->lsf_cache->fci_lock);
+       if (rc)
+               OBD_FREE_PTR(flde);
+out:
+       RETURN(rc);
 }
 
 /**
@@ -250,40 +230,20 @@ int fld_index_delete(struct lu_server_fld *fld,
  * \retval -ENOENT      not found, \a range is the left-side range;
  * \retval  -ve         other error;
  */
-
-int fld_index_lookup(struct lu_server_fld *fld,
-                     const struct lu_env *env,
-                     seqno_t seq,
-                     struct lu_seq_range *range)
+int fld_index_lookup(const struct lu_env *env, struct lu_server_fld *fld,
+                    u64 seq, struct lu_seq_range *range)
 {
-        struct dt_object        *dt_obj = fld->lsf_obj;
         struct lu_seq_range     *fld_rec;
-        struct dt_key           *key = fld_key(env, seq);
         struct fld_thread_info  *info;
         int rc;
 
         ENTRY;
 
-       if (fld->lsf_no_range_lookup) {
-               /* Stub for underlying FS which can't lookup ranges */
-               range->lsr_start = 0;
-               range->lsr_end = ~0;
-               range->lsr_index = 0;
-               range->lsr_flags = LU_SEQ_RANGE_MDT;
-
-               range_cpu_to_be(range, range);
-               return 0;
-       }
-
-        info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
-        fld_rec = &info->fti_rec;
+       info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
+       fld_rec = &info->fti_rec;
 
-        rc = dt_obj->do_index_ops->dio_lookup(env, dt_obj,
-                                              (struct dt_rec*) fld_rec,
-                                              key, BYPASS_CAPA);
-
-        if (rc >= 0) {
-                range_be_to_cpu(fld_rec, fld_rec);
+       rc = fld_cache_lookup(fld->lsf_cache, seq, fld_rec);
+       if (rc == 0) {
                 *range = *fld_rec;
                 if (range_within(range, seq))
                         rc = 0;
@@ -297,102 +257,256 @@ int fld_index_lookup(struct lu_server_fld *fld,
         RETURN(rc);
 }
 
-static int fld_insert_igif_fld(struct lu_server_fld *fld,
-                               const struct lu_env *env)
+/**
+ * insert entry in fld store.
+ *
+ * \param  env    relevant lu_env
+ * \param  fld    fld store
+ * \param  range  range to be inserted
+ *
+ * \retval  0  success
+ * \retval  -ve error
+ *
+ * Caller must hold fld->lsf_lock
+ **/
+
+int fld_insert_entry(const struct lu_env *env,
+                    struct lu_server_fld *fld,
+                    const struct lu_seq_range *range)
 {
-        struct thandle *th;
-        int rc;
-        ENTRY;
+       struct thandle *th;
+       int rc;
+       ENTRY;
 
-        /* FLD_TXN_INDEX_INSERT_CREDITS */
-        th = fld_trans_create(fld, env);
-        if (IS_ERR(th))
-                RETURN(PTR_ERR(th));
-        rc = fld_declare_index_create(fld, env, &IGIF_FLD_RANGE, th);
-        if (rc) {
-                fld_trans_stop(fld, env, th);
-                RETURN(rc);
-        }
-        rc = fld_trans_start(fld, env, th);
-        if (rc) {
-                fld_trans_stop(fld, env, th);
-                RETURN(rc);
-        }
+       LASSERT(mutex_is_locked(&fld->lsf_lock));
 
-        rc = fld_index_create(fld, env, &IGIF_FLD_RANGE, th);
-        fld_trans_stop(fld, env, th);
-        if (rc == -EEXIST)
-                rc = 0;
-        RETURN(rc);
+       th = dt_trans_create(env, lu2dt_dev(fld->lsf_obj->do_lu.lo_dev));
+       if (IS_ERR(th))
+               RETURN(PTR_ERR(th));
+
+       rc = fld_declare_index_create(env, fld, range, th);
+       if (rc != 0) {
+               if (rc == -EEXIST)
+                       rc = 0;
+               GOTO(out, rc);
+       }
+
+       rc = dt_trans_start_local(env, lu2dt_dev(fld->lsf_obj->do_lu.lo_dev),
+                                 th);
+       if (rc)
+               GOTO(out, rc);
+
+       rc = fld_index_create(env, fld, range, th);
+       if (rc == -EEXIST)
+               rc = 0;
+out:
+       dt_trans_stop(env, lu2dt_dev(fld->lsf_obj->do_lu.lo_dev), th);
+       RETURN(rc);
 }
+EXPORT_SYMBOL(fld_insert_entry);
 
-int fld_index_init(struct lu_server_fld *fld,
-                   const struct lu_env *env,
-                   struct dt_device *dt)
+static int fld_insert_special_entries(const struct lu_env *env,
+                                     struct lu_server_fld *fld)
 {
-        struct dt_object *dt_obj;
-        struct lu_fid fid;
-       struct lu_attr attr;
-       struct dt_object_format dof;
-        int rc;
-        ENTRY;
+       int rc;
+
+       rc = fld_insert_entry(env, fld, &IGIF_FLD_RANGE);
+       if (rc != 0)
+               RETURN(rc);
+
+       rc = fld_insert_entry(env, fld, &DOT_LUSTRE_FLD_RANGE);
+       if (rc != 0)
+               RETURN(rc);
+
+       rc = fld_insert_entry(env, fld, &ROOT_FLD_RANGE);
+
+       RETURN(rc);
+}
+
+int fld_index_init(const struct lu_env *env, struct lu_server_fld *fld,
+                  struct dt_device *dt, int type)
+{
+       struct dt_object        *dt_obj = NULL;
+       struct lu_fid           fid;
+       struct lu_attr          *attr = NULL;
+       struct lu_seq_range     *range = NULL;
+       struct fld_thread_info  *info;
+       struct dt_object_format dof;
+       struct dt_it            *it;
+       const struct dt_it_ops  *iops;
+       int                     rc;
+       __u32                   index;
+       ENTRY;
+
+       info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
+       LASSERT(info != NULL);
 
        lu_local_obj_fid(&fid, FLD_INDEX_OID);
+       OBD_ALLOC_PTR(attr);
+       if (attr == NULL)
+               RETURN(-ENOMEM);
 
-       memset(&attr, 0, sizeof(attr));
-       attr.la_valid = LA_MODE;
-       attr.la_mode = S_IFREG | 0666;
+       memset(attr, 0, sizeof(*attr));
+       attr->la_valid = LA_MODE;
+       attr->la_mode = S_IFREG | 0666;
        dof.dof_type = DFT_INDEX;
        dof.u.dof_idx.di_feat = &fld_index_features;
 
-       dt_obj = dt_find_or_create(env, dt, &fid, &dof, &attr);
-        if (!IS_ERR(dt_obj)) {
-                fld->lsf_obj = dt_obj;
-                rc = dt_obj->do_ops->do_index_try(env, dt_obj,
-                                                  &fld_index_features);
-                if (rc == 0) {
-                        LASSERT(dt_obj->do_index_ops != NULL);
-                        rc = fld_insert_igif_fld(fld, env);
-
-                        if (rc != 0) {
-                                CERROR("insert igif in fld! = %d\n", rc);
-                                lu_object_put(env, &dt_obj->do_lu);
-                                fld->lsf_obj = NULL;
-                        }
-               } else if (rc == -ERANGE) {
-                       CWARN("%s: File \"%s\" doesn't support range lookup, "
-                             "using stub. DNE and FIDs on OST will not work "
-                             "with this backend\n",
-                             fld->lsf_name, fld_index_name);
-
-                       LASSERT(dt_obj->do_index_ops == NULL);
-                       fld->lsf_no_range_lookup = 1;
-                       rc = 0;
-               } else {
-                       CERROR("%s: File \"%s\" is not index, rc %d!\n",
-                              fld->lsf_name, fld_index_name, rc);
-                       lu_object_put(env, &fld->lsf_obj->do_lu);
-                       fld->lsf_obj = NULL;
+       dt_obj = dt_locate(env, dt, &fid);
+       if (IS_ERR(dt_obj)) {
+               rc = PTR_ERR(dt_obj);
+               dt_obj = NULL;
+               GOTO(out, rc);
+       }
+
+       LASSERT(dt_obj != NULL);
+       if (!dt_object_exists(dt_obj)) {
+               lu_object_put(env, &dt_obj->do_lu);
+               dt_obj = dt_find_or_create(env, dt, &fid, &dof, attr);
+               fld->lsf_new = 1;
+               if (IS_ERR(dt_obj)) {
+                       rc = PTR_ERR(dt_obj);
+                       CERROR("%s: Can't find \"%s\" obj %d\n", fld->lsf_name,
+                               fld_index_name, rc);
+                       dt_obj = NULL;
+                       GOTO(out, rc);
                }
+       }
 
+       fld->lsf_obj = dt_obj;
+       rc = dt_obj->do_ops->do_index_try(env, dt_obj, &fld_index_features);
+       if (rc != 0) {
+               CERROR("%s: File \"%s\" is not an index: rc = %d!\n",
+                      fld->lsf_name, fld_index_name, rc);
+               GOTO(out, rc);
+       }
 
-        } else {
-                CERROR("%s: Can't find \"%s\" obj %d\n",
-                       fld->lsf_name, fld_index_name, (int)PTR_ERR(dt_obj));
-                rc = PTR_ERR(dt_obj);
-        }
+       range = &info->fti_rec;
+       /* Load fld entry to cache */
+       iops = &dt_obj->do_index_ops->dio_it;
+       it = iops->init(env, dt_obj, 0);
+       if (IS_ERR(it))
+               GOTO(out, rc = PTR_ERR(it));
+
+       rc = iops->load(env, it, 0);
+       if (rc < 0)
+               GOTO(out_it_fini, rc);
+
+       if (rc > 0) {
+               /* Load FLD entry into server cache */
+               do {
+                       rc = iops->rec(env, it, (struct dt_rec *)range, 0);
+                       if (rc != 0)
+                               GOTO(out_it_put, rc);
+                       LASSERT(range != NULL);
+                       range_be_to_cpu(range, range);
+                       rc = fld_cache_insert(fld->lsf_cache, range);
+                       if (rc != 0)
+                               GOTO(out_it_put, rc);
+                       rc = iops->next(env, it);
+               } while (rc == 0);
+       } else {
+               fld->lsf_new = 1;
+       }
 
-        RETURN(rc);
+       rc = fld_name_to_index(fld->lsf_name, &index);
+       if (rc < 0)
+               GOTO(out_it_put, rc);
+       else
+               rc = 0;
+
+       if (index == 0 && type == LU_SEQ_RANGE_MDT) {
+               /* Note: fld_insert_entry will detect whether these
+                * special entries already exist inside FLDB */
+               mutex_lock(&fld->lsf_lock);
+               rc = fld_insert_special_entries(env, fld);
+               mutex_unlock(&fld->lsf_lock);
+               if (rc != 0) {
+                       CERROR("%s: insert special entries failed!: rc = %d\n",
+                              fld->lsf_name, rc);
+                       GOTO(out_it_put, rc);
+               }
+       }
+out_it_put:
+       iops->put(env, it);
+out_it_fini:
+       iops->fini(env, it);
+out:
+       if (attr != NULL)
+               OBD_FREE_PTR(attr);
+
+       if (rc < 0) {
+               if (dt_obj != NULL)
+                       lu_object_put(env, &dt_obj->do_lu);
+               fld->lsf_obj = NULL;
+       }
+       RETURN(rc);
 }
 
-void fld_index_fini(struct lu_server_fld *fld,
-                    const struct lu_env *env)
+void fld_index_fini(const struct lu_env *env, struct lu_server_fld *fld)
 {
-        ENTRY;
-        if (fld->lsf_obj != NULL) {
-                if (!IS_ERR(fld->lsf_obj))
-                        lu_object_put(env, &fld->lsf_obj->do_lu);
-                fld->lsf_obj = NULL;
-        }
-        EXIT;
+       ENTRY;
+       if (fld->lsf_obj != NULL) {
+               if (!IS_ERR(fld->lsf_obj))
+                       lu_object_put(env, &fld->lsf_obj->do_lu);
+               fld->lsf_obj = NULL;
+       }
+       EXIT;
+}
+
+int fld_server_read(const struct lu_env *env, struct lu_server_fld *fld,
+                   struct lu_seq_range *range, void *data, int data_len)
+{
+       struct lu_seq_range_array *lsra = data;
+       struct fld_thread_info    *info;
+       struct dt_object          *dt_obj = fld->lsf_obj;
+       struct lu_seq_range       *entry;
+       struct dt_it              *it;
+       const struct dt_it_ops    *iops;
+       int                       rc;
+
+       ENTRY;
+
+       lsra->lsra_count = 0;
+       iops = &dt_obj->do_index_ops->dio_it;
+       it = iops->init(env, dt_obj, 0);
+       if (IS_ERR(it))
+               RETURN(PTR_ERR(it));
+
+       rc = iops->load(env, it, range->lsr_end);
+       if (rc <= 0)
+               GOTO(out_it_fini, rc);
+
+       info = lu_context_key_get(&env->le_ctx, &fld_thread_key);
+       LASSERT(info != NULL);
+       entry = &info->fti_rec;
+       do {
+               rc = iops->rec(env, it, (struct dt_rec *)entry, 0);
+               if (rc != 0)
+                       GOTO(out_it_put, rc);
+
+               if (offsetof(typeof(*lsra), lsra_lsr[lsra->lsra_count + 1]) >
+                   data_len)
+                       GOTO(out, rc = -EAGAIN);
+
+               range_be_to_cpu(entry, entry);
+               if (entry->lsr_index == range->lsr_index &&
+                   entry->lsr_flags == range->lsr_flags &&
+                   entry->lsr_start > range->lsr_start) {
+                       lsra->lsra_lsr[lsra->lsra_count] = *entry;
+                       lsra->lsra_count++;
+               }
+
+               rc = iops->next(env, it);
+       } while (rc == 0);
+       if (rc > 0)
+               rc = 0;
+out:
+       range_array_cpu_to_le(lsra, lsra);
+out_it_put:
+       iops->put(env, it);
+out_it_fini:
+       iops->fini(env, it);
+
+       RETURN(rc);
 }