Whamcloud - gitweb
LU-4423 style: Change comment to fit within 80 columns
[fs/lustre-release.git] / lustre / llite / statahead.c
index 537b44d..bb75469 100644 (file)
@@ -1,6 +1,4 @@
-/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
- * vim:expandtab:shiftwidth=8:tabstop=8:
- *
+/*
  * GPL HEADER START
  *
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
@@ -29,8 +27,7 @@
  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2011 Whamcloud, Inc.
- *
+ * Copyright (c) 2011, 2013, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -40,7 +37,6 @@
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
-#include <linux/smp_lock.h>
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
 
@@ -49,7 +45,6 @@
 #include <obd_support.h>
 #include <lustre_lite.h>
 #include <lustre_dlm.h>
-#include <linux/lustre_version.h>
 #include "llite_internal.h"
 
 #define SA_OMITTED_ENTRY_MAX 8ULL
@@ -63,37 +58,34 @@ typedef enum {
 } se_stat_t;
 
 struct ll_sa_entry {
-        /* link into sai->sai_entries_{sent,received,stated} */
-        cfs_list_t              se_list;
-        /* link into sai hash table locally */
-        cfs_list_t              se_hash;
-        /* entry reference count */
-        cfs_atomic_t            se_refcount;
-        /* entry index in the sai */
-        __u64                   se_index;
-        /* low layer ldlm lock handle */
-        __u64                   se_handle;
-        /* entry status */
-        se_stat_t               se_stat;
-        /* entry size, contains name */
-        int                     se_size;
-        /* pointer to async getattr enqueue info */
-        struct md_enqueue_info *se_minfo;
-        /* pointer to the async getattr request */
-        struct ptlrpc_request  *se_req;
-        /* pointer to the target inode */
-        struct inode           *se_inode;
-        /* entry name */
-        struct qstr             se_qstr;
+       /* link into sai->sai_entries */
+       cfs_list_t              se_link;
+       /* link into sai->sai_entries_{received,stated} */
+       cfs_list_t              se_list;
+       /* link into sai hash table locally */
+       cfs_list_t              se_hash;
+       /* entry reference count */
+       atomic_t            se_refcount;
+       /* entry index in the sai */
+       __u64                   se_index;
+       /* low layer ldlm lock handle */
+       __u64                   se_handle;
+       /* entry status */
+       se_stat_t               se_stat;
+       /* entry size, contains name */
+       int                     se_size;
+       /* pointer to async getattr enqueue info */
+       struct md_enqueue_info *se_minfo;
+       /* pointer to the async getattr request */
+       struct ptlrpc_request  *se_req;
+       /* pointer to the target inode */
+       struct inode           *se_inode;
+       /* entry name */
+       struct qstr             se_qstr;
 };
 
 static unsigned int sai_generation = 0;
-static cfs_spinlock_t sai_generation_lock = CFS_SPIN_LOCK_UNLOCKED;
-
-static inline int ll_sa_entry_unlinked(struct ll_sa_entry *entry)
-{
-        return cfs_list_empty(&entry->se_list);
-}
+static DEFINE_SPINLOCK(sai_generation_lock);
 
 static inline int ll_sa_entry_unhashed(struct ll_sa_entry *entry)
 {
@@ -120,11 +112,11 @@ static inline int ll_sa_entry_hash(int val)
 static inline void
 ll_sa_entry_enhash(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 {
-        int i = ll_sa_entry_hash(entry->se_qstr.hash);
+       int i = ll_sa_entry_hash(entry->se_qstr.hash);
 
-        cfs_spin_lock(&sai->sai_cache_lock[i]);
-        cfs_list_add_tail(&entry->se_hash, &sai->sai_cache[i]);
-        cfs_spin_unlock(&sai->sai_cache_lock[i]);
+       spin_lock(&sai->sai_cache_lock[i]);
+       cfs_list_add_tail(&entry->se_hash, &sai->sai_cache[i]);
+       spin_unlock(&sai->sai_cache_lock[i]);
 }
 
 /*
@@ -133,20 +125,17 @@ ll_sa_entry_enhash(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 static inline void
 ll_sa_entry_unhash(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 {
-        int i = ll_sa_entry_hash(entry->se_qstr.hash);
+       int i = ll_sa_entry_hash(entry->se_qstr.hash);
 
-        cfs_spin_lock(&sai->sai_cache_lock[i]);
-        cfs_list_del_init(&entry->se_hash);
-        cfs_spin_unlock(&sai->sai_cache_lock[i]);
+       spin_lock(&sai->sai_cache_lock[i]);
+       cfs_list_del_init(&entry->se_hash);
+       spin_unlock(&sai->sai_cache_lock[i]);
 }
 
 static inline int agl_should_run(struct ll_statahead_info *sai,
                                  struct inode *inode)
 {
-        if (inode != NULL && S_ISREG(inode->i_mode) &&
-            ll_i2info(inode)->lli_smd != NULL && sai->sai_agl_valid)
-                return 1;
-        return 0;
+       return (inode != NULL && S_ISREG(inode->i_mode) && sai->sai_agl_valid);
 }
 
 static inline struct ll_sa_entry *
@@ -165,7 +154,7 @@ agl_first_entry(struct ll_statahead_info *sai)
 
 static inline int sa_sent_full(struct ll_statahead_info *sai)
 {
-        return cfs_atomic_read(&sai->sai_cache_count) >= sai->sai_max;
+       return atomic_read(&sai->sai_cache_count) >= sai->sai_max;
 }
 
 static inline int sa_received_empty(struct ll_statahead_info *sai)
@@ -201,7 +190,7 @@ static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
 }
 
 /*
- * Insert it into sai_entries_sent tail when init.
+ * Insert it into sai_entries tail when init.
  */
 static struct ll_sa_entry *
 ll_sa_entry_alloc(struct ll_statahead_info *sai, __u64 index,
@@ -218,53 +207,54 @@ ll_sa_entry_alloc(struct ll_statahead_info *sai, __u64 index,
         if (unlikely(entry == NULL))
                 RETURN(ERR_PTR(-ENOMEM));
 
-        CDEBUG(D_READA, "alloc sai entry %.*s(%p) index "LPU64"\n",
-               len, name, entry, index);
+       CDEBUG(D_READA, "alloc sa entry %.*s(%p) index "LPU64"\n",
+              len, name, entry, index);
 
         entry->se_index = index;
 
-        /*
-         * Statahead entry reference rules:
-         *
-         * 1) When statahead entry is initialized, its reference is set as 2.
-         *    One reference is used by the directory scanner. When the scanner
-         *    searches the statahead cache for the given name, it can perform
-         *    lockless hash lookup (only the scanner can remove entry from hash
-         *    list), and once found, it needn't to call "atomic_inc()" for the
-         *    entry reference. So the performance is improved. After using the
-         *    statahead entry, the scanner will call "atomic_dec()" to drop the
-         *    reference held when initialization. If it is the last reference,
-         *    the statahead entry will be freed.
-         *
-         * 2) All other threads, including statahead thread and ptlrpcd thread,
-         *    when they process the statahead entry, the reference for target
-         *    should be held to guarantee the entry will not be released by the
-         *    directory scanner. After processing the entry, these threads will
-         *    drop the entry reference. If it is the last reference, the entry
-         *    will be freed.
-         *
-         *    The second reference when initializes the statahead entry is used
-         *    by the statahead thread, following the rule 2).
-         */
-        cfs_atomic_set(&entry->se_refcount, 2);
-        entry->se_stat = SA_ENTRY_INIT;
-        entry->se_size = entry_size;
-        dname = (char *)entry + sizeof(struct ll_sa_entry);
-        memcpy(dname, name, len);
-        dname[len] = 0;
-        entry->se_qstr.hash = full_name_hash(name, len);
-        entry->se_qstr.len = len;
-        entry->se_qstr.name = dname;
-
-        lli = ll_i2info(sai->sai_inode);
-        cfs_spin_lock(&lli->lli_sa_lock);
-        cfs_list_add_tail(&entry->se_list, &sai->sai_entries_sent);
-        cfs_spin_unlock(&lli->lli_sa_lock);
-
-        cfs_atomic_inc(&sai->sai_cache_count);
-        ll_sa_entry_enhash(sai, entry);
-
-        RETURN(entry);
+       /*
+        * Statahead entry reference rules:
+        *
+        * 1) When statahead entry is initialized, its reference is set as 2.
+        *    One reference is used by the directory scanner. When the scanner
+        *    searches the statahead cache for the given name, it can perform
+        *    lockless hash lookup (only the scanner can remove entry from hash
+        *    list), and once found, it needn't to call "atomic_inc()" for the
+        *    entry reference. So the performance is improved. After using the
+        *    statahead entry, the scanner will call "atomic_dec()" to drop the
+        *    reference held when initialization. If it is the last reference,
+        *    the statahead entry will be freed.
+        *
+        * 2) All other threads, including statahead thread and ptlrpcd thread,
+        *    when they process the statahead entry, the reference for target
+        *    should be held to guarantee the entry will not be released by the
+        *    directory scanner. After processing the entry, these threads will
+        *    drop the entry reference. If it is the last reference, the entry
+        *    will be freed.
+        *
+        *    The second reference when initializes the statahead entry is used
+        *    by the statahead thread, following the rule 2).
+        */
+       atomic_set(&entry->se_refcount, 2);
+       entry->se_stat = SA_ENTRY_INIT;
+       entry->se_size = entry_size;
+       dname = (char *)entry + sizeof(struct ll_sa_entry);
+       memcpy(dname, name, len);
+       dname[len] = 0;
+       entry->se_qstr.hash = full_name_hash(name, len);
+       entry->se_qstr.len = len;
+       entry->se_qstr.name = dname;
+
+       lli = ll_i2info(sai->sai_inode);
+       spin_lock(&lli->lli_sa_lock);
+       cfs_list_add_tail(&entry->se_link, &sai->sai_entries);
+       CFS_INIT_LIST_HEAD(&entry->se_list);
+       ll_sa_entry_enhash(sai, entry);
+       spin_unlock(&lli->lli_sa_lock);
+
+       atomic_inc(&sai->sai_cache_count);
+
+       RETURN(entry);
 }
 
 /*
@@ -299,17 +289,18 @@ ll_sa_entry_get_byname(struct ll_statahead_info *sai, const struct qstr *qstr)
 static struct ll_sa_entry *
 ll_sa_entry_get_byindex(struct ll_statahead_info *sai, __u64 index)
 {
-        struct ll_sa_entry *entry;
+       struct ll_sa_entry *entry;
 
-        cfs_list_for_each_entry(entry, &sai->sai_entries_sent, se_list) {
-                if (entry->se_index == index) {
-                        cfs_atomic_inc(&entry->se_refcount);
-                        return entry;
+       cfs_list_for_each_entry(entry, &sai->sai_entries, se_link) {
+               if (entry->se_index == index) {
+                       LASSERT(atomic_read(&entry->se_refcount) > 0);
+                       atomic_inc(&entry->se_refcount);
+                       return entry;
                 }
-                if (entry->se_index > index)
-                        break;
-        }
-        return NULL;
+               if (entry->se_index > index)
+                       break;
+       }
+       return NULL;
 }
 
 static void ll_sa_entry_cleanup(struct ll_statahead_info *sai,
@@ -334,37 +325,42 @@ static void ll_sa_entry_cleanup(struct ll_statahead_info *sai,
 static void ll_sa_entry_put(struct ll_statahead_info *sai,
                              struct ll_sa_entry *entry)
 {
-        if (cfs_atomic_dec_and_test(&entry->se_refcount)) {
-                CDEBUG(D_READA, "free sai entry %.*s(%p) index "LPU64"\n",
-                       entry->se_qstr.len, entry->se_qstr.name, entry,
-                       entry->se_index);
-
-                LASSERT(ll_sa_entry_unhashed(entry));
-                LASSERT(ll_sa_entry_unlinked(entry));
-
-                ll_sa_entry_cleanup(sai, entry);
-                if (entry->se_inode)
-                        iput(entry->se_inode);
-
-                OBD_FREE(entry, entry->se_size);
-                cfs_atomic_dec(&sai->sai_cache_count);
-        }
+       if (atomic_dec_and_test(&entry->se_refcount)) {
+               CDEBUG(D_READA, "free sa entry %.*s(%p) index "LPU64"\n",
+                      entry->se_qstr.len, entry->se_qstr.name, entry,
+                      entry->se_index);
+
+               LASSERT(cfs_list_empty(&entry->se_link));
+               LASSERT(cfs_list_empty(&entry->se_list));
+               LASSERT(ll_sa_entry_unhashed(entry));
+
+               ll_sa_entry_cleanup(sai, entry);
+               if (entry->se_inode)
+                       iput(entry->se_inode);
+
+               OBD_FREE(entry, entry->se_size);
+               atomic_dec(&sai->sai_cache_count);
+       }
 }
 
 static inline void
-do_sai_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
+do_sa_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 {
-        struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
+       struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 
-        ll_sa_entry_unhash(sai, entry);
+       LASSERT(!ll_sa_entry_unhashed(entry));
+       LASSERT(!cfs_list_empty(&entry->se_link));
 
-        cfs_spin_lock(&lli->lli_sa_lock);
-        entry->se_stat = SA_ENTRY_DEST;
-        if (likely(!ll_sa_entry_unlinked(entry)))
-                cfs_list_del_init(&entry->se_list);
-        cfs_spin_unlock(&lli->lli_sa_lock);
+       ll_sa_entry_unhash(sai, entry);
 
-        ll_sa_entry_put(sai, entry);
+       spin_lock(&lli->lli_sa_lock);
+       entry->se_stat = SA_ENTRY_DEST;
+       cfs_list_del_init(&entry->se_link);
+       if (likely(!cfs_list_empty(&entry->se_list)))
+               cfs_list_del_init(&entry->se_list);
+       spin_unlock(&lli->lli_sa_lock);
+
+       ll_sa_entry_put(sai, entry);
 }
 
 /*
@@ -373,52 +369,41 @@ do_sai_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 static void
 ll_sa_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 {
-        struct ll_sa_entry *pos, *next;
-
-        if (entry)
-                do_sai_entry_fini(sai, entry);
+       struct ll_sa_entry *pos, *next;
 
-        /* drop old entry from sent list */
-        cfs_list_for_each_entry_safe(pos, next, &sai->sai_entries_sent,
-                                     se_list) {
-                if (is_omitted_entry(sai, pos->se_index))
-                        do_sai_entry_fini(sai, pos);
-                else
-                        break;
-        }
+       if (entry)
+               do_sa_entry_fini(sai, entry);
 
-        /* drop old entry from stated list */
-        cfs_list_for_each_entry_safe(pos, next, &sai->sai_entries_stated,
-                                     se_list) {
-                if (is_omitted_entry(sai, pos->se_index))
-                        do_sai_entry_fini(sai, pos);
-                else
-                        break;
-        }
+       /* drop old entry, only 'scanner' process does this, no need to lock */
+       cfs_list_for_each_entry_safe(pos, next, &sai->sai_entries, se_link) {
+               if (!is_omitted_entry(sai, pos->se_index))
+                       break;
+               do_sa_entry_fini(sai, pos);
+       }
 }
 
 /*
  * Inside lli_sa_lock.
  */
 static void
-do_sai_entry_to_stated(struct ll_statahead_info *sai,
-                       struct ll_sa_entry *entry, int rc)
+do_sa_entry_to_stated(struct ll_statahead_info *sai,
+                     struct ll_sa_entry *entry, se_stat_t stat)
 {
-        struct ll_sa_entry *se;
-        cfs_list_t         *pos = &sai->sai_entries_stated;
+       struct ll_sa_entry *se;
+       cfs_list_t         *pos = &sai->sai_entries_stated;
 
-        if (!ll_sa_entry_unlinked(entry))
-                cfs_list_del_init(&entry->se_list);
+       if (!cfs_list_empty(&entry->se_list))
+               cfs_list_del_init(&entry->se_list);
 
-        cfs_list_for_each_entry_reverse(se, &sai->sai_entries_stated, se_list) {
-                if (se->se_index < entry->se_index) {
-                        pos = &se->se_list;
-                        break;
-                }
-        }
+       cfs_list_for_each_entry_reverse(se, &sai->sai_entries_stated, se_list) {
+               if (se->se_index < entry->se_index) {
+                       pos = &se->se_list;
+                       break;
+               }
+       }
 
-        cfs_list_add(&entry->se_list, pos);
-        entry->se_stat = rc;
+       cfs_list_add(&entry->se_list, pos);
+       entry->se_stat = stat;
 }
 
 /*
@@ -428,21 +413,21 @@ do_sai_entry_to_stated(struct ll_statahead_info *sai,
  */
 static int
 ll_sa_entry_to_stated(struct ll_statahead_info *sai,
-                       struct ll_sa_entry *entry, int rc)
+                     struct ll_sa_entry *entry, se_stat_t stat)
 {
-        struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
-        int                   ret = 1;
+       struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
+       int                   ret = 1;
 
-        ll_sa_entry_cleanup(sai, entry);
+       ll_sa_entry_cleanup(sai, entry);
 
-        cfs_spin_lock(&lli->lli_sa_lock);
-        if (likely(entry->se_stat != SA_ENTRY_DEST)) {
-                do_sai_entry_to_stated(sai, entry, rc);
-                ret = 0;
-        }
-        cfs_spin_unlock(&lli->lli_sa_lock);
+       spin_lock(&lli->lli_sa_lock);
+       if (likely(entry->se_stat != SA_ENTRY_DEST)) {
+               do_sa_entry_to_stated(sai, entry, stat);
+               ret = 0;
+       }
+       spin_unlock(&lli->lli_sa_lock);
 
-        return ret;
+       return ret;
 }
 
 /*
@@ -451,99 +436,99 @@ ll_sa_entry_to_stated(struct ll_statahead_info *sai,
 static void ll_agl_add(struct ll_statahead_info *sai,
                        struct inode *inode, int index)
 {
-        struct ll_inode_info *child  = ll_i2info(inode);
-        struct ll_inode_info *parent = ll_i2info(sai->sai_inode);
-        int                   added  = 0;
-
-        cfs_spin_lock(&child->lli_agl_lock);
-        if (child->lli_agl_index == 0) {
-                child->lli_agl_index = index;
-                cfs_spin_unlock(&child->lli_agl_lock);
-
-                LASSERT(cfs_list_empty(&child->lli_agl_list));
-
-                igrab(inode);
-                cfs_spin_lock(&parent->lli_agl_lock);
-                if (agl_list_empty(sai))
-                        added = 1;
-                cfs_list_add_tail(&child->lli_agl_list, &sai->sai_entries_agl);
-                cfs_spin_unlock(&parent->lli_agl_lock);
-        } else {
-                cfs_spin_unlock(&child->lli_agl_lock);
-        }
-
-        if (added > 0)
-                cfs_waitq_signal(&sai->sai_agl_thread.t_ctl_waitq);
+       struct ll_inode_info *child  = ll_i2info(inode);
+       struct ll_inode_info *parent = ll_i2info(sai->sai_inode);
+       int                   added  = 0;
+
+       spin_lock(&child->lli_agl_lock);
+       if (child->lli_agl_index == 0) {
+               child->lli_agl_index = index;
+               spin_unlock(&child->lli_agl_lock);
+
+               LASSERT(cfs_list_empty(&child->lli_agl_list));
+
+               igrab(inode);
+               spin_lock(&parent->lli_agl_lock);
+               if (agl_list_empty(sai))
+                       added = 1;
+               cfs_list_add_tail(&child->lli_agl_list, &sai->sai_entries_agl);
+               spin_unlock(&parent->lli_agl_lock);
+       } else {
+               spin_unlock(&child->lli_agl_lock);
+       }
+
+       if (added > 0)
+               wake_up(&sai->sai_agl_thread.t_ctl_waitq);
 }
 
 static struct ll_statahead_info *ll_sai_alloc(void)
 {
-        struct ll_statahead_info *sai;
-        int                       i;
-        ENTRY;
-
-        OBD_ALLOC_PTR(sai);
-        if (!sai)
-                RETURN(NULL);
-
-        cfs_atomic_set(&sai->sai_refcount, 1);
-
-        cfs_spin_lock(&sai_generation_lock);
-        sai->sai_generation = ++sai_generation;
-        if (unlikely(sai_generation == 0))
-                sai->sai_generation = ++sai_generation;
-        cfs_spin_unlock(&sai_generation_lock);
-
-        sai->sai_max = LL_SA_RPC_MIN;
-        sai->sai_index = 1;
-        cfs_waitq_init(&sai->sai_waitq);
-        cfs_waitq_init(&sai->sai_thread.t_ctl_waitq);
-        cfs_waitq_init(&sai->sai_agl_thread.t_ctl_waitq);
-
-        CFS_INIT_LIST_HEAD(&sai->sai_entries_sent);
-        CFS_INIT_LIST_HEAD(&sai->sai_entries_received);
-        CFS_INIT_LIST_HEAD(&sai->sai_entries_stated);
-        CFS_INIT_LIST_HEAD(&sai->sai_entries_agl);
-
-        for (i = 0; i < LL_SA_CACHE_SIZE; i++) {
-                CFS_INIT_LIST_HEAD(&sai->sai_cache[i]);
-                cfs_spin_lock_init(&sai->sai_cache_lock[i]);
-        }
-        cfs_atomic_set(&sai->sai_cache_count, 0);
-
-        RETURN(sai);
+       struct ll_statahead_info *sai;
+       int                       i;
+       ENTRY;
+
+       OBD_ALLOC_PTR(sai);
+       if (!sai)
+               RETURN(NULL);
+
+       atomic_set(&sai->sai_refcount, 1);
+
+       spin_lock(&sai_generation_lock);
+       sai->sai_generation = ++sai_generation;
+       if (unlikely(sai_generation == 0))
+               sai->sai_generation = ++sai_generation;
+       spin_unlock(&sai_generation_lock);
+
+       sai->sai_max = LL_SA_RPC_MIN;
+       sai->sai_index = 1;
+       init_waitqueue_head(&sai->sai_waitq);
+       init_waitqueue_head(&sai->sai_thread.t_ctl_waitq);
+       init_waitqueue_head(&sai->sai_agl_thread.t_ctl_waitq);
+
+       CFS_INIT_LIST_HEAD(&sai->sai_entries);
+       CFS_INIT_LIST_HEAD(&sai->sai_entries_received);
+       CFS_INIT_LIST_HEAD(&sai->sai_entries_stated);
+       CFS_INIT_LIST_HEAD(&sai->sai_entries_agl);
+
+       for (i = 0; i < LL_SA_CACHE_SIZE; i++) {
+               CFS_INIT_LIST_HEAD(&sai->sai_cache[i]);
+               spin_lock_init(&sai->sai_cache_lock[i]);
+       }
+       atomic_set(&sai->sai_cache_count, 0);
+
+       RETURN(sai);
 }
 
 static inline struct ll_statahead_info *
 ll_sai_get(struct ll_statahead_info *sai)
 {
-        cfs_atomic_inc(&sai->sai_refcount);
-        return sai;
+       atomic_inc(&sai->sai_refcount);
+       return sai;
 }
 
 static void ll_sai_put(struct ll_statahead_info *sai)
 {
-        struct inode         *inode = sai->sai_inode;
-        struct ll_inode_info *lli   = ll_i2info(inode);
-        ENTRY;
+       struct inode         *inode = sai->sai_inode;
+       struct ll_inode_info *lli   = ll_i2info(inode);
+       ENTRY;
 
-        if (cfs_atomic_dec_and_lock(&sai->sai_refcount, &lli->lli_sa_lock)) {
-                struct ll_sa_entry *entry, *next;
+       if (atomic_dec_and_lock(&sai->sai_refcount, &lli->lli_sa_lock)) {
+               struct ll_sa_entry *entry, *next;
 
-                if (unlikely(cfs_atomic_read(&sai->sai_refcount) > 0)) {
-                        /* It is race case, the interpret callback just hold
-                         * a reference count */
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                        RETURN_EXIT;
-                }
+               if (unlikely(atomic_read(&sai->sai_refcount) > 0)) {
+                       /* It is race case, the interpret callback just hold
+                        * a reference count */
+                       spin_unlock(&lli->lli_sa_lock);
+                       RETURN_EXIT;
+               }
 
-                LASSERT(lli->lli_opendir_key == NULL);
-                LASSERT(thread_is_stopped(&sai->sai_thread));
-                LASSERT(thread_is_stopped(&sai->sai_agl_thread));
+               LASSERT(lli->lli_opendir_key == NULL);
+               LASSERT(thread_is_stopped(&sai->sai_thread));
+               LASSERT(thread_is_stopped(&sai->sai_agl_thread));
 
-                lli->lli_sai = NULL;
-                lli->lli_opendir_pid = 0;
-                cfs_spin_unlock(&lli->lli_sa_lock);
+               lli->lli_sai = NULL;
+               lli->lli_opendir_pid = 0;
+               spin_unlock(&lli->lli_sa_lock);
 
                 if (sai->sai_sent > sai->sai_replied)
                         CDEBUG(D_READA,"statahead for dir "DFID" does not "
@@ -551,30 +536,24 @@ static void ll_sai_put(struct ll_statahead_info *sai)
                               PFID(&lli->lli_fid),
                               sai->sai_sent, sai->sai_replied);
 
-                cfs_list_for_each_entry_safe(entry, next,
-                                             &sai->sai_entries_sent, se_list)
-                        do_sai_entry_fini(sai, entry);
-
-                LASSERT(sa_received_empty(sai));
+               cfs_list_for_each_entry_safe(entry, next,
+                                            &sai->sai_entries, se_link)
+                       do_sa_entry_fini(sai, entry);
 
-                cfs_list_for_each_entry_safe(entry, next,
-                                             &sai->sai_entries_stated, se_list)
-                        do_sai_entry_fini(sai, entry);
+               LASSERT(list_empty(&sai->sai_entries));
+               LASSERT(sa_received_empty(sai));
+               LASSERT(list_empty(&sai->sai_entries_stated));
 
-                LASSERT(cfs_atomic_read(&sai->sai_cache_count) == 0);
-                LASSERT(agl_list_empty(sai));
+               LASSERT(atomic_read(&sai->sai_cache_count) == 0);
+               LASSERT(agl_list_empty(sai));
 
-                iput(inode);
-                OBD_FREE_PTR(sai);
-        }
+               iput(inode);
+               OBD_FREE_PTR(sai);
+       }
 
-        EXIT;
+       EXIT;
 }
 
-#ifndef HAVE_AGL_SUPPORT
-# define cl_agl(inode)  do {} while (0)
-#endif
-
 /* Do NOT forget to drop inode refcount when into sai_entries_agl. */
 static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
 {
@@ -593,7 +572,7 @@ static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
         }
 
         /* Someone is in glimpse (sync or async), do nothing. */
-        rc = cfs_down_write_trylock(&lli->lli_glimpse_sem);
+       rc = down_write_trylock(&lli->lli_glimpse_sem);
         if (rc == 0) {
                 lli->lli_agl_index = 0;
                 iput(inode);
@@ -615,7 +594,7 @@ static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
          */
         if (lli->lli_glimpse_time != 0 &&
             cfs_time_before(cfs_time_shift(-1), lli->lli_glimpse_time)) {
-                cfs_up_write(&lli->lli_glimpse_sem);
+               up_write(&lli->lli_glimpse_sem);
                 lli->lli_agl_index = 0;
                 iput(inode);
                 RETURN_EXIT;
@@ -627,7 +606,7 @@ static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
         cl_agl(inode);
         lli->lli_agl_index = 0;
         lli->lli_glimpse_time = cfs_time_current();
-        cfs_up_write(&lli->lli_glimpse_sem);
+       up_write(&lli->lli_glimpse_sem);
 
         CDEBUG(D_READA, "Handled (init) async glimpse: inode= "
                DFID", idx = "LPU64", rc = %d\n",
@@ -638,8 +617,7 @@ static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
         EXIT;
 }
 
-static void do_statahead_interpret(struct ll_statahead_info *sai,
-                                   struct ll_sa_entry *target)
+static void ll_post_statahead(struct ll_statahead_info *sai)
 {
         struct inode           *dir   = sai->sai_inode;
         struct inode           *child;
@@ -652,20 +630,15 @@ static void do_statahead_interpret(struct ll_statahead_info *sai,
         int                     rc    = 0;
         ENTRY;
 
-        cfs_spin_lock(&lli->lli_sa_lock);
-        if (target != NULL && target->se_req != NULL &&
-            !cfs_list_empty(&target->se_list)) {
-                entry = target;
-        } else if (unlikely(sa_received_empty(sai))) {
-                cfs_spin_unlock(&lli->lli_sa_lock);
-                RETURN_EXIT;
-        } else {
-                entry = sa_first_received_entry(sai);
-        }
-
-        cfs_atomic_inc(&entry->se_refcount);
-        cfs_list_del_init(&entry->se_list);
-        cfs_spin_unlock(&lli->lli_sa_lock);
+       spin_lock(&lli->lli_sa_lock);
+       if (unlikely(sa_received_empty(sai))) {
+               spin_unlock(&lli->lli_sa_lock);
+               RETURN_EXIT;
+       }
+       entry = sa_first_received_entry(sai);
+       atomic_inc(&entry->se_refcount);
+       cfs_list_del_init(&entry->se_list);
+       spin_unlock(&lli->lli_sa_lock);
 
         LASSERT(entry->se_handle != 0);
 
@@ -700,16 +673,17 @@ static void do_statahead_interpret(struct ll_statahead_info *sai,
         }
 
         it->d.lustre.it_lock_handle = entry->se_handle;
-        rc = md_revalidate_lock(ll_i2mdexp(dir), it, NULL, NULL);
+       rc = md_revalidate_lock(ll_i2mdexp(dir), it, ll_inode2fid(dir), NULL);
         if (rc != 1)
                 GOTO(out, rc = -EAGAIN);
 
-        rc = ll_prep_inode(&child, req, dir->i_sb);
+        rc = ll_prep_inode(&child, req, dir->i_sb, it);
         if (rc)
                 GOTO(out, rc);
 
-        CDEBUG(D_DLMTRACE, "setting l_data to inode %p (%lu/%u)\n",
-               child, child->i_ino, child->i_generation);
+       CDEBUG(D_DLMTRACE, "%s: setting l_data to inode "DFID"(%p)\n",
+              ll_get_fsname(child->i_sb, NULL, 0),
+              PFID(ll_inode2fid(child)), child);
         ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
 
         entry->se_inode = child;
@@ -720,14 +694,15 @@ static void do_statahead_interpret(struct ll_statahead_info *sai,
         EXIT;
 
 out:
-        /* The "ll_sa_entry_to_stated()" will drop related ldlm ibits lock
-         * reference count by calling "ll_intent_drop_lock()" in spite of the
-         * above operations failed or not. Do not worry about calling
-         * "ll_intent_drop_lock()" more than once. */
-        rc = ll_sa_entry_to_stated(sai, entry, rc < 0 ? rc : SA_ENTRY_SUCC);
-        if (rc == 0 && entry->se_index == sai->sai_index_wait && target == NULL)
-                cfs_waitq_signal(&sai->sai_waitq);
-        ll_sa_entry_put(sai, entry);
+       /* The "ll_sa_entry_to_stated()" will drop related ldlm ibits lock
+        * reference count by calling "ll_intent_drop_lock()" in spite of the
+        * above operations failed or not. Do not worry about calling
+        * "ll_intent_drop_lock()" more than once. */
+       rc = ll_sa_entry_to_stated(sai, entry,
+                                  rc < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC);
+       if (rc == 0 && entry->se_index == sai->sai_index_wait)
+               wake_up(&sai->sai_waitq);
+       ll_sa_entry_put(sai, entry);
 }
 
 static int ll_statahead_interpret(struct ptlrpc_request *req,
@@ -744,52 +719,49 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
         if (it_disposition(it, DISP_LOOKUP_NEG))
                 rc = -ENOENT;
 
-        cfs_spin_lock(&lli->lli_sa_lock);
-        /* stale entry */
-        if (unlikely(lli->lli_sai == NULL ||
-                     lli->lli_sai->sai_generation != minfo->mi_generation)) {
-                cfs_spin_unlock(&lli->lli_sa_lock);
-                GOTO(out, rc = -ESTALE);
-        } else {
-                sai = ll_sai_get(lli->lli_sai);
-                if (unlikely(!thread_is_running(&sai->sai_thread))) {
-                        sai->sai_replied++;
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                        GOTO(out, rc = -EBADFD);
-                }
-
-                entry = ll_sa_entry_get_byindex(sai, minfo->mi_cbdata);
-                if (entry == NULL) {
-                        sai->sai_replied++;
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                        GOTO(out, rc = -EIDRM);
-                }
-
-                cfs_list_del_init(&entry->se_list);
-                if (rc != 0) {
-                        sai->sai_replied++;
-                        do_sai_entry_to_stated(sai, entry, rc);
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                        if (entry->se_index == sai->sai_index_wait)
-                                cfs_waitq_signal(&sai->sai_waitq);
+       spin_lock(&lli->lli_sa_lock);
+       /* stale entry */
+       if (unlikely(lli->lli_sai == NULL ||
+                    lli->lli_sai->sai_generation != minfo->mi_generation)) {
+               spin_unlock(&lli->lli_sa_lock);
+               GOTO(out, rc = -ESTALE);
+       } else {
+               sai = ll_sai_get(lli->lli_sai);
+               if (unlikely(!thread_is_running(&sai->sai_thread))) {
+                       sai->sai_replied++;
+                       spin_unlock(&lli->lli_sa_lock);
+                       GOTO(out, rc = -EBADFD);
+               }
+
+               entry = ll_sa_entry_get_byindex(sai, minfo->mi_cbdata);
+               if (entry == NULL) {
+                       sai->sai_replied++;
+                       spin_unlock(&lli->lli_sa_lock);
+                       GOTO(out, rc = -EIDRM);
+               }
+
+               if (rc != 0) {
+                       do_sa_entry_to_stated(sai, entry, SA_ENTRY_INVA);
+                       wakeup = (entry->se_index == sai->sai_index_wait);
                 } else {
-                        entry->se_minfo = minfo;
-                        entry->se_req = ptlrpc_request_addref(req);
-                        /* Release the async ibits lock ASAP to avoid deadlock
-                         * when statahead thread tries to enqueue lock on parent
-                         * for readpage and other tries to enqueue lock on child
-                         * with parent's lock held, for example: unlink. */
-                        entry->se_handle = it->d.lustre.it_lock_handle;
-                        ll_intent_drop_lock(it);
-                        wakeup = sa_received_empty(sai);
-                        cfs_list_add_tail(&entry->se_list,
-                                          &sai->sai_entries_received);
-                        sai->sai_replied++;
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                        if (wakeup)
-                                cfs_waitq_signal(&sai->sai_thread.t_ctl_waitq);
+                       entry->se_minfo = minfo;
+                       entry->se_req = ptlrpc_request_addref(req);
+                       /* Release the async ibits lock ASAP to avoid deadlock
+                        * when statahead thread tries to enqueue lock on parent
+                        * for readpage and other tries to enqueue lock on child
+                        * with parent's lock held, for example: unlink. */
+                       entry->se_handle = it->d.lustre.it_lock_handle;
+                       ll_intent_drop_lock(it);
+                       wakeup = sa_received_empty(sai);
+                       cfs_list_add_tail(&entry->se_list,
+                                         &sai->sai_entries_received);
                 }
-                ll_sa_entry_put(sai, entry);
+               sai->sai_replied++;
+               spin_unlock(&lli->lli_sa_lock);
+
+               ll_sa_entry_put(sai, entry);
+               if (wakeup)
+                       wake_up(&sai->sai_thread.t_ctl_waitq);
         }
 
         EXIT;
@@ -922,9 +894,6 @@ static int do_sa_revalidate(struct inode *dir, struct ll_sa_entry *entry,
         if (d_mountpoint(dentry))
                 RETURN(1);
 
-        if (unlikely(dentry == dentry->d_sb->s_root))
-                RETURN(1);
-
         entry->se_inode = igrab(inode);
         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),NULL);
         if (rc == 1) {
@@ -982,14 +951,14 @@ static void ll_statahead_one(struct dentry *parent, const char* entry_name,
         if (dentry != NULL)
                 dput(dentry);
 
-        if (rc) {
-                rc1 = ll_sa_entry_to_stated(sai, entry,
-                                        rc < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC);
-                if (rc1 == 0 && entry->se_index == sai->sai_index_wait)
-                        cfs_waitq_signal(&sai->sai_waitq);
-        } else {
-                sai->sai_sent++;
-        }
+       if (rc) {
+               rc1 = ll_sa_entry_to_stated(sai, entry,
+                                       rc < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC);
+               if (rc1 == 0 && entry->se_index == sai->sai_index_wait)
+                       wake_up(&sai->sai_waitq);
+       } else {
+               sai->sai_sent++;
+       }
 
         sai->sai_index++;
         /* drop one refcount on entry by ll_sa_entry_alloc */
@@ -1010,21 +979,20 @@ static int ll_agl_thread(void *arg)
         struct l_wait_info        lwi    = { 0 };
         ENTRY;
 
-        {
-                char pname[16];
-                snprintf(pname, 15, "ll_agl_%u", plli->lli_opendir_pid);
-                cfs_daemonize(pname);
-        }
-
-        CDEBUG(D_READA, "agl thread started: [pid %d] [parent %.*s]\n",
-               cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
-
-        atomic_inc(&sbi->ll_agl_total);
-        cfs_spin_lock(&plli->lli_agl_lock);
-        sai->sai_agl_valid = 1;
-        thread_set_flags(thread, SVC_RUNNING);
-        cfs_spin_unlock(&plli->lli_agl_lock);
-        cfs_waitq_signal(&thread->t_ctl_waitq);
+       thread->t_pid = current_pid();
+       CDEBUG(D_READA, "agl thread started: sai %p, parent %.*s\n",
+              sai, parent->d_name.len, parent->d_name.name);
+
+       atomic_inc(&sbi->ll_agl_total);
+       spin_lock(&plli->lli_agl_lock);
+       sai->sai_agl_valid = 1;
+       if (thread_is_init(thread))
+               /* If someone else has changed the thread state
+                * (e.g. already changed to SVC_STOPPING), we can't just
+                * blindly overwrite that setting. */
+               thread_set_flags(thread, SVC_RUNNING);
+       spin_unlock(&plli->lli_agl_lock);
+       wake_up(&thread->t_ctl_waitq);
 
         while (1) {
                 l_wait_event(thread->t_ctl_waitq,
@@ -1035,305 +1003,281 @@ static int ll_agl_thread(void *arg)
                 if (!thread_is_running(thread))
                         break;
 
-                cfs_spin_lock(&plli->lli_agl_lock);
-                /* The statahead thread maybe help to process AGL entries,
-                 * so check whether list empty again. */
-                if (!agl_list_empty(sai)) {
-                        clli = agl_first_entry(sai);
-                        cfs_list_del_init(&clli->lli_agl_list);
-                        cfs_spin_unlock(&plli->lli_agl_lock);
-                        ll_agl_trigger(&clli->lli_vfs_inode, sai);
-                } else {
-                        cfs_spin_unlock(&plli->lli_agl_lock);
-                }
-        }
-
-        cfs_spin_lock(&plli->lli_agl_lock);
-        sai->sai_agl_valid = 0;
-        while (!agl_list_empty(sai)) {
-                clli = agl_first_entry(sai);
-                cfs_list_del_init(&clli->lli_agl_list);
-                cfs_spin_unlock(&plli->lli_agl_lock);
-                clli->lli_agl_index = 0;
-                iput(&clli->lli_vfs_inode);
-                cfs_spin_lock(&plli->lli_agl_lock);
-        }
-        thread_set_flags(thread, SVC_STOPPED);
-        cfs_spin_unlock(&plli->lli_agl_lock);
-        cfs_waitq_signal(&thread->t_ctl_waitq);
-        ll_sai_put(sai);
-        CDEBUG(D_READA, "agl thread stopped: [pid %d] [parent %.*s]\n",
-               cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
-        RETURN(0);
+               spin_lock(&plli->lli_agl_lock);
+               /* The statahead thread maybe help to process AGL entries,
+                * so check whether list empty again. */
+               if (!agl_list_empty(sai)) {
+                       clli = agl_first_entry(sai);
+                       cfs_list_del_init(&clli->lli_agl_list);
+                       spin_unlock(&plli->lli_agl_lock);
+                       ll_agl_trigger(&clli->lli_vfs_inode, sai);
+               } else {
+                       spin_unlock(&plli->lli_agl_lock);
+               }
+       }
+
+       spin_lock(&plli->lli_agl_lock);
+       sai->sai_agl_valid = 0;
+       while (!agl_list_empty(sai)) {
+               clli = agl_first_entry(sai);
+               cfs_list_del_init(&clli->lli_agl_list);
+               spin_unlock(&plli->lli_agl_lock);
+               clli->lli_agl_index = 0;
+               iput(&clli->lli_vfs_inode);
+               spin_lock(&plli->lli_agl_lock);
+       }
+       thread_set_flags(thread, SVC_STOPPED);
+       spin_unlock(&plli->lli_agl_lock);
+       wake_up(&thread->t_ctl_waitq);
+       ll_sai_put(sai);
+       CDEBUG(D_READA, "agl thread stopped: sai %p, parent %.*s\n",
+              sai, parent->d_name.len, parent->d_name.name);
+       RETURN(0);
 }
 
 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
 {
-        struct ptlrpc_thread *thread = &sai->sai_agl_thread;
-        struct l_wait_info    lwi    = { 0 };
-        int                   rc;
-        ENTRY;
-
-        CDEBUG(D_READA, "start agl thread: [pid %d] [parent %.*s]\n",
-               cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
-
-        rc = cfs_create_thread(ll_agl_thread, parent, 0);
-        if (rc < 0) {
-                CERROR("can't start ll_agl thread, rc: %d\n", rc);
-                RETURN_EXIT;
-        }
-
-        l_wait_event(thread->t_ctl_waitq,
-                     thread_is_running(thread) || thread_is_stopped(thread),
-                     &lwi);
-        EXIT;
+       struct ptlrpc_thread *thread = &sai->sai_agl_thread;
+       struct l_wait_info    lwi    = { 0 };
+       struct ll_inode_info  *plli;
+       struct task_struct            *task;
+       ENTRY;
+
+       CDEBUG(D_READA, "start agl thread: sai %p, parent %.*s\n",
+              sai, parent->d_name.len, parent->d_name.name);
+
+       plli = ll_i2info(parent->d_inode);
+       task = kthread_run(ll_agl_thread, parent,
+                              "ll_agl_%u", plli->lli_opendir_pid);
+       if (IS_ERR(task)) {
+               CERROR("can't start ll_agl thread, rc: %ld\n", PTR_ERR(task));
+               thread_set_flags(thread, SVC_STOPPED);
+               RETURN_EXIT;
+       }
+
+       l_wait_event(thread->t_ctl_waitq,
+                    thread_is_running(thread) || thread_is_stopped(thread),
+                    &lwi);
+       EXIT;
 }
 
 static int ll_statahead_thread(void *arg)
 {
-        struct dentry            *parent = (struct dentry *)arg;
-        struct inode             *dir    = parent->d_inode;
-        struct ll_inode_info     *plli   = ll_i2info(dir);
-        struct ll_inode_info     *clli;
-        struct ll_sb_info        *sbi    = ll_i2sbi(dir);
-        struct ll_statahead_info *sai    = ll_sai_get(plli->lli_sai);
-        struct ptlrpc_thread     *thread = &sai->sai_thread;
-        struct page              *page;
-        __u64                     pos    = 0;
-        int                       first  = 0;
-        int                       rc     = 0;
-        struct ll_dir_chain       chain;
-        struct l_wait_info        lwi    = { 0 };
-        ENTRY;
+       struct dentry            *parent = (struct dentry *)arg;
+       struct inode             *dir    = parent->d_inode;
+       struct ll_inode_info     *plli   = ll_i2info(dir);
+       struct ll_inode_info     *clli;
+       struct ll_sb_info        *sbi    = ll_i2sbi(dir);
+       struct ll_statahead_info *sai    = ll_sai_get(plli->lli_sai);
+       struct ptlrpc_thread     *thread = &sai->sai_thread;
+       struct ptlrpc_thread *agl_thread = &sai->sai_agl_thread;
+       int                       first  = 0;
+       int                       rc     = 0;
+       struct md_op_data        *op_data;
+       struct ll_dir_chain       chain;
+       struct l_wait_info        lwi    = { 0 };
+       struct lu_dirent         *ent;
+       struct page             *page = NULL;
+       ENTRY;
+
+       thread->t_pid = current_pid();
+       CDEBUG(D_READA, "statahead thread starting: sai %p, parent %.*s\n",
+              sai, parent->d_name.len, parent->d_name.name);
+
+       op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
+                                    LUSTRE_OPC_ANY, dir);
+       if (IS_ERR(op_data))
+               RETURN(PTR_ERR(op_data));
+
+       op_data->op_hash_offset = 0;
+       op_data->op_max_pages =
+               ll_i2sbi(dir)->ll_md_brw_size >> PAGE_CACHE_SHIFT;
+
+       if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
+               ll_start_agl(parent, sai);
+
+       atomic_inc(&sbi->ll_sa_total);
+       spin_lock(&plli->lli_sa_lock);
+       if (thread_is_init(thread))
+               /* If someone else has changed the thread state
+                * (e.g. already changed to SVC_STOPPING), we can't just
+                * blindly overwrite that setting. */
+               thread_set_flags(thread, SVC_RUNNING);
+       spin_unlock(&plli->lli_sa_lock);
+       wake_up(&thread->t_ctl_waitq);
+
+       ll_dir_chain_init(&chain);
+       for (ent = ll_dir_entry_start(dir, op_data, &page);
+            ent != NULL && !IS_ERR(ent);
+            ent = ll_dir_entry_next(dir, op_data, ent, &page)) {
+               __u64 hash;
+               int namelen;
+               char *name;
+
+               hash = le64_to_cpu(ent->lde_hash);
+               if (unlikely(hash < op_data->op_hash_offset))
+                       /*
+                        * Skip until we find target hash value.
+                        */
+                       continue;
+
+               namelen = le16_to_cpu(ent->lde_namelen);
+               if (unlikely(namelen == 0))
+                       /*
+                        * Skip dummy record.
+                        */
+                       continue;
+
+               name = ent->lde_name;
+               if (name[0] == '.') {
+                       if (namelen == 1) {
+                               /*
+                                * skip "."
+                                */
+                               continue;
+                       } else if (name[1] == '.' && namelen == 2) {
+                               /*
+                                * skip ".."
+                                */
+                               continue;
+                       } else if (!sai->sai_ls_all) {
+                               /*
+                                * skip hidden files.
+                                */
+                               sai->sai_skip_hidden++;
+                               continue;
+                       }
+               }
+
+               /*
+                * don't stat-ahead first entry.
+                */
+               if (unlikely(++first == 1))
+                       continue;
 
-        {
-                char pname[16];
-                snprintf(pname, 15, "ll_sa_%u", plli->lli_opendir_pid);
-                cfs_daemonize(pname);
-        }
-
-        CDEBUG(D_READA, "statahead thread started: [pid %d] [parent %.*s]\n",
-               cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
-
-        if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
-                ll_start_agl(parent, sai);
-
-        atomic_inc(&sbi->ll_sa_total);
-        cfs_spin_lock(&plli->lli_sa_lock);
-        thread_set_flags(thread, SVC_RUNNING);
-        cfs_spin_unlock(&plli->lli_sa_lock);
-        cfs_waitq_signal(&thread->t_ctl_waitq);
-
-        plli->lli_sa_pos = 0;
-        ll_dir_chain_init(&chain);
-        page = ll_get_dir_page(NULL, dir, pos, &chain);
-
-        while (1) {
-                struct lu_dirpage *dp;
-                struct lu_dirent  *ent;
-
-                if (IS_ERR(page)) {
-                        rc = PTR_ERR(page);
-                        CDEBUG(D_READA, "error reading dir "DFID" at "LPU64
-                               "/"LPU64": [rc %d] [parent %u]\n",
-                               PFID(ll_inode2fid(dir)), pos, sai->sai_index,
-                               rc, plli->lli_opendir_pid);
-                        GOTO(out, rc);
-                }
+keep_it:
+               l_wait_event(thread->t_ctl_waitq,
+                            !sa_sent_full(sai) ||
+                            !sa_received_empty(sai) ||
+                            !agl_list_empty(sai) ||
+                            !thread_is_running(thread),
+                            &lwi);
 
-                dp = page_address(page);
-                for (ent = lu_dirent_start(dp); ent != NULL;
-                     ent = lu_dirent_next(ent)) {
-                        __u64 hash;
-                        int namelen;
-                        char *name;
+interpret_it:
+               while (!sa_received_empty(sai))
+                       ll_post_statahead(sai);
 
-                        hash = le64_to_cpu(ent->lde_hash);
-                        if (unlikely(hash < pos))
-                                /*
-                                 * Skip until we find target hash value.
-                                 */
-                                continue;
+               if (unlikely(!thread_is_running(thread)))
+                       GOTO(out, rc = 0);
 
-                        namelen = le16_to_cpu(ent->lde_namelen);
-                        if (unlikely(namelen == 0))
-                                /*
-                                 * Skip dummy record.
-                                 */
-                                continue;
+               /* If no window for metadata statahead, but there are
+                * some AGL entries to be triggered, then try to help
+                * to process the AGL entries. */
+               if (sa_sent_full(sai)) {
+                       spin_lock(&plli->lli_agl_lock);
+                       while (!agl_list_empty(sai)) {
+                               clli = agl_first_entry(sai);
+                               cfs_list_del_init(&clli->lli_agl_list);
+                               spin_unlock(&plli->lli_agl_lock);
+                               ll_agl_trigger(&clli->lli_vfs_inode,
+                                              sai);
 
-                        name = ent->lde_name;
-                        if (name[0] == '.') {
-                                if (namelen == 1) {
-                                        /*
-                                         * skip "."
-                                         */
-                                        continue;
-                                } else if (name[1] == '.' && namelen == 2) {
-                                        /*
-                                         * skip ".."
-                                         */
-                                        continue;
-                                } else if (!sai->sai_ls_all) {
-                                        /*
-                                         * skip hidden files.
-                                         */
-                                        sai->sai_skip_hidden++;
-                                        continue;
-                                }
-                        }
+                               if (!sa_received_empty(sai))
+                                       goto interpret_it;
 
-                        /*
-                         * don't stat-ahead first entry.
-                         */
-                        if (unlikely(++first == 1))
-                                continue;
+                               if (unlikely(
+                                       !thread_is_running(thread)))
+                                       GOTO(out, rc = 0);
 
-keep_it:
-                        l_wait_event(thread->t_ctl_waitq,
-                                     !sa_sent_full(sai) ||
-                                     !sa_received_empty(sai) ||
-                                     !agl_list_empty(sai) ||
-                                     !thread_is_running(thread),
-                                     &lwi);
+                               if (!sa_sent_full(sai))
+                                       goto do_it;
 
-interpret_it:
-                        while (!sa_received_empty(sai))
-                                do_statahead_interpret(sai, NULL);
+                               spin_lock(&plli->lli_agl_lock);
+                       }
+                       spin_unlock(&plli->lli_agl_lock);
 
-                        if (unlikely(!thread_is_running(thread))) {
-                                ll_release_page(page, 0);
-                                GOTO(out, rc = 0);
-                        }
-
-                        /* If no window for metadata statahead, but there are
-                         * some AGL entries to be triggered, then try to help
-                         * to process the AGL entries. */
-                        if (sa_sent_full(sai)) {
-                                cfs_spin_lock(&plli->lli_agl_lock);
-                                while (!agl_list_empty(sai)) {
-                                        clli = agl_first_entry(sai);
-                                        cfs_list_del_init(&clli->lli_agl_list);
-                                        cfs_spin_unlock(&plli->lli_agl_lock);
-                                        ll_agl_trigger(&clli->lli_vfs_inode,
-                                                       sai);
-
-                                        if (!sa_received_empty(sai))
-                                                goto interpret_it;
-
-                                        if (unlikely(
-                                                !thread_is_running(thread))) {
-                                                ll_release_page(page, 0);
-                                                GOTO(out, rc = 0);
-                                        }
-
-                                        if (!sa_sent_full(sai))
-                                                goto do_it;
-
-                                        cfs_spin_lock(&plli->lli_agl_lock);
-                                }
-                                cfs_spin_unlock(&plli->lli_agl_lock);
-
-                                goto keep_it;
-                        }
+                       goto keep_it;
+               }
 
 do_it:
-                        ll_statahead_one(parent, name, namelen);
-                }
-                pos = le64_to_cpu(dp->ldp_hash_end);
-                if (pos == MDS_DIR_END_OFF) {
-                        /*
-                         * End of directory reached.
-                         */
-                        ll_release_page(page, 0);
-                        while (1) {
-                                l_wait_event(thread->t_ctl_waitq,
-                                             !sa_received_empty(sai) ||
-                                             sai->sai_sent == sai->sai_replied||
-                                             !thread_is_running(thread),
-                                             &lwi);
-
-                                while (!sa_received_empty(sai))
-                                        do_statahead_interpret(sai, NULL);
-
-                                if (unlikely(!thread_is_running(thread)))
-                                        GOTO(out, rc = 0);
-
-                                if (sai->sai_sent == sai->sai_replied &&
-                                    sa_received_empty(sai))
-                                        break;
-                        }
-
-                        cfs_spin_lock(&plli->lli_agl_lock);
-                        while (!agl_list_empty(sai) &&
-                               thread_is_running(thread)) {
-                                clli = agl_first_entry(sai);
-                                cfs_list_del_init(&clli->lli_agl_list);
-                                cfs_spin_unlock(&plli->lli_agl_lock);
-                                ll_agl_trigger(&clli->lli_vfs_inode, sai);
-                                cfs_spin_lock(&plli->lli_agl_lock);
-                        }
-                        cfs_spin_unlock(&plli->lli_agl_lock);
-
-                        GOTO(out, rc = 0);
-                } else if (1) {
-                        /*
-                         * chain is exhausted.
-                         * Normal case: continue to the next page.
-                         */
-                        ll_release_page(page, le32_to_cpu(dp->ldp_flags) &
-                                              LDF_COLLIDE);
-                        plli->lli_sa_pos = pos;
-                        sai->sai_in_readpage = 1;
-                        page = ll_get_dir_page(NULL, dir, pos, &chain);
-                        sai->sai_in_readpage = 0;
-                } else {
-                        LASSERT(le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
-                        ll_release_page(page, 1);
-                        /*
-                         * go into overflow page.
-                         */
-                }
-        }
-        EXIT;
-
+               ll_statahead_one(parent, name, namelen);
+       }
+
+       if (page != NULL) {
+               kunmap(page);
+               page_cache_release(page);
+       }
+
+        /*
+        * End of directory reached.
+        */
+       while (1) {
+               l_wait_event(thread->t_ctl_waitq,
+                            !sa_received_empty(sai) ||
+                            sai->sai_sent == sai->sai_replied ||
+                            !thread_is_running(thread),
+                            &lwi);
+
+               while (!sa_received_empty(sai))
+                       ll_post_statahead(sai);
+
+               if (unlikely(!thread_is_running(thread)))
+                       GOTO(out, rc = 0);
+
+               if (sai->sai_sent == sai->sai_replied &&
+                   sa_received_empty(sai))
+                       break;
+       }
+
+       spin_lock(&plli->lli_agl_lock);
+       while (!agl_list_empty(sai) &&
+              thread_is_running(thread)) {
+               clli = agl_first_entry(sai);
+               cfs_list_del_init(&clli->lli_agl_list);
+               spin_unlock(&plli->lli_agl_lock);
+               ll_agl_trigger(&clli->lli_vfs_inode, sai);
+               spin_lock(&plli->lli_agl_lock);
+       }
+       spin_unlock(&plli->lli_agl_lock);
 out:
+       EXIT;
+       ll_finish_md_op_data(op_data);
         if (sai->sai_agl_valid) {
-                struct ptlrpc_thread *agl_thread = &sai->sai_agl_thread;
-
-                cfs_spin_lock(&plli->lli_agl_lock);
-                thread_set_flags(agl_thread, SVC_STOPPING);
-                cfs_spin_unlock(&plli->lli_agl_lock);
-                cfs_waitq_signal(&agl_thread->t_ctl_waitq);
-
-                CDEBUG(D_READA, "stop agl thread: [pid %d]\n",
-                       cfs_curproc_pid());
-                l_wait_event(agl_thread->t_ctl_waitq,
-                             thread_is_stopped(agl_thread),
-                             &lwi);
+               spin_lock(&plli->lli_agl_lock);
+               thread_set_flags(agl_thread, SVC_STOPPING);
+               spin_unlock(&plli->lli_agl_lock);
+               wake_up(&agl_thread->t_ctl_waitq);
+
+               CDEBUG(D_READA, "stop agl thread: sai %p pid %u\n",
+                      sai, (unsigned int)agl_thread->t_pid);
+               l_wait_event(agl_thread->t_ctl_waitq,
+                            thread_is_stopped(agl_thread),
+                            &lwi);
+        } else {
+                /* Set agl_thread flags anyway. */
+                thread_set_flags(&sai->sai_agl_thread, SVC_STOPPED);
         }
-
         ll_dir_chain_fini(&chain);
-        cfs_spin_lock(&plli->lli_sa_lock);
-        if (!sa_received_empty(sai)) {
-                thread_set_flags(thread, SVC_STOPPING);
-                cfs_spin_unlock(&plli->lli_sa_lock);
-
-                /* To release the resources held by received entries. */
-                while (!sa_received_empty(sai))
-                        do_statahead_interpret(sai, NULL);
-
-                cfs_spin_lock(&plli->lli_sa_lock);
-        }
-        thread_set_flags(thread, SVC_STOPPED);
-        cfs_spin_unlock(&plli->lli_sa_lock);
-        cfs_waitq_signal(&sai->sai_waitq);
-        cfs_waitq_signal(&thread->t_ctl_waitq);
+       spin_lock(&plli->lli_sa_lock);
+       if (!sa_received_empty(sai)) {
+               thread_set_flags(thread, SVC_STOPPING);
+               spin_unlock(&plli->lli_sa_lock);
+
+               /* To release the resources held by received entries. */
+               while (!sa_received_empty(sai))
+                       ll_post_statahead(sai);
+
+               spin_lock(&plli->lli_sa_lock);
+       }
+       thread_set_flags(thread, SVC_STOPPED);
+       spin_unlock(&plli->lli_sa_lock);
+       wake_up(&sai->sai_waitq);
+       wake_up(&thread->t_ctl_waitq);
         ll_sai_put(sai);
         dput(parent);
-        CDEBUG(D_READA, "statahead thread stopped: [pid %d] [parent %.*s]\n",
-               cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
-        return rc;
+       CDEBUG(D_READA, "statahead thread stopped: sai %p, parent %.*s\n",
+              sai, parent->d_name.len, parent->d_name.name);
+       return rc;
 }
 
 /**
@@ -1341,14 +1285,14 @@ out:
  */
 void ll_stop_statahead(struct inode *dir, void *key)
 {
-        struct ll_inode_info *lli = ll_i2info(dir);
+       struct ll_inode_info *lli = ll_i2info(dir);
 
-        if (unlikely(key == NULL))
-                return;
+       if (unlikely(key == NULL))
+               return;
 
-        cfs_spin_lock(&lli->lli_sa_lock);
-        if (lli->lli_opendir_key != key || lli->lli_opendir_pid == 0) {
-                cfs_spin_unlock(&lli->lli_sa_lock);
+       spin_lock(&lli->lli_sa_lock);
+       if (lli->lli_opendir_key != key || lli->lli_opendir_pid == 0) {
+               spin_unlock(&lli->lli_sa_lock);
                 return;
         }
 
@@ -1360,28 +1304,28 @@ void ll_stop_statahead(struct inode *dir, void *key)
 
                 if (!thread_is_stopped(thread)) {
                         thread_set_flags(thread, SVC_STOPPING);
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                        cfs_waitq_signal(&thread->t_ctl_waitq);
-
-                        CDEBUG(D_READA, "stop statahead thread: [pid %d]\n",
-                               cfs_curproc_pid());
-                        l_wait_event(thread->t_ctl_waitq,
-                                     thread_is_stopped(thread),
-                                     &lwi);
-                } else {
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                }
-
-                /*
-                 * Put the ref which was held when first statahead_enter.
-                 * It maybe not the last ref for some statahead requests
-                 * maybe inflight.
-                 */
-                ll_sai_put(lli->lli_sai);
-        } else {
-                lli->lli_opendir_pid = 0;
-                cfs_spin_unlock(&lli->lli_sa_lock);
-        }
+                       spin_unlock(&lli->lli_sa_lock);
+                       wake_up(&thread->t_ctl_waitq);
+
+                       CDEBUG(D_READA, "stop statahead thread: sai %p pid %u\n",
+                              lli->lli_sai, (unsigned int)thread->t_pid);
+                       l_wait_event(thread->t_ctl_waitq,
+                                    thread_is_stopped(thread),
+                                    &lwi);
+               } else {
+                       spin_unlock(&lli->lli_sa_lock);
+               }
+
+               /*
+                * Put the ref which was held when first statahead_enter.
+                * It maybe not the last ref for some statahead requests
+                * maybe inflight.
+                */
+               ll_sai_put(lli->lli_sai);
+       } else {
+               lli->lli_opendir_pid = 0;
+               spin_unlock(&lli->lli_sa_lock);
+       }
 }
 
 enum {
@@ -1401,118 +1345,93 @@ enum {
 
 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
 {
-        struct ll_inode_info *lli    = ll_i2info(dir);
-        struct ll_dir_chain   chain;
-        struct qstr          *target = &dentry->d_name;
-        struct page          *page;
-        __u64                 pos    = 0;
-        int                   dot_de;
-        int                   rc     = LS_NONE_FIRST_DE;
-        ENTRY;
-
-        lli->lli_sa_pos = 0;
-        ll_dir_chain_init(&chain);
-        page = ll_get_dir_page(NULL, dir, pos, &chain);
-
-        while (1) {
-                struct lu_dirpage *dp;
-                struct lu_dirent  *ent;
-
-                if (IS_ERR(page)) {
-                        struct ll_inode_info *lli = ll_i2info(dir);
-
-                        rc = PTR_ERR(page);
-                        CERROR("error reading dir "DFID" at "LPU64": "
-                               "[rc %d] [parent %u]\n",
-                               PFID(ll_inode2fid(dir)), pos,
-                               rc, lli->lli_opendir_pid);
-                        break;
-                }
-
-                dp = page_address(page);
-                for (ent = lu_dirent_start(dp); ent != NULL;
-                     ent = lu_dirent_next(ent)) {
-                        __u64 hash;
-                        int namelen;
-                        char *name;
-
-                        hash = le64_to_cpu(ent->lde_hash);
-                        /* The ll_get_dir_page() can return any page containing
-                         * the given hash which may be not the start hash. */
-                        if (unlikely(hash < pos))
-                                continue;
-
-                        namelen = le16_to_cpu(ent->lde_namelen);
-                        if (unlikely(namelen == 0))
-                                /*
-                                 * skip dummy record.
-                                 */
-                                continue;
-
-                        name = ent->lde_name;
-                        if (name[0] == '.') {
-                                if (namelen == 1)
-                                        /*
-                                         * skip "."
-                                         */
-                                        continue;
-                                else if (name[1] == '.' && namelen == 2)
-                                        /*
-                                         * skip ".."
-                                         */
-                                        continue;
-                                else
-                                        dot_de = 1;
-                        } else {
-                                dot_de = 0;
-                        }
-
-                        if (dot_de && target->name[0] != '.') {
-                                CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
-                                       target->len, target->name,
-                                       namelen, name);
-                                continue;
-                        }
-
-                        if (target->len != namelen ||
-                            memcmp(target->name, name, namelen) != 0)
-                                rc = LS_NONE_FIRST_DE;
-                        else if (!dot_de)
-                                rc = LS_FIRST_DE;
-                        else
-                                rc = LS_FIRST_DOT_DE;
-
-                        ll_release_page(page, 0);
-                        GOTO(out, rc);
-                }
-                pos = le64_to_cpu(dp->ldp_hash_end);
-                if (pos == MDS_DIR_END_OFF) {
-                        /*
-                         * End of directory reached.
-                         */
-                        ll_release_page(page, 0);
-                        break;
-                } else if (1) {
-                        /*
-                         * chain is exhausted
-                         * Normal case: continue to the next page.
-                         */
-                        ll_release_page(page, le32_to_cpu(dp->ldp_flags) &
-                                              LDF_COLLIDE);
-                        lli->lli_sa_pos = pos;
-                        page = ll_get_dir_page(NULL, dir, pos, &chain);
-                } else {
-                        /*
-                         * go into overflow page.
-                         */
-                        LASSERT(le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
-                        ll_release_page(page, 1);
-                }
-        }
+       struct ll_dir_chain   chain;
+       struct qstr          *target = &dentry->d_name;
+       struct md_op_data    *op_data;
+       int                   dot_de;
+       struct lu_dirent     *ent;
+       struct page          *page = NULL;
+       int                   rc     = LS_NONE_FIRST_DE;
+       ENTRY;
+
+       ll_dir_chain_init(&chain);
+
+       op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
+                                    LUSTRE_OPC_ANY, dir);
+       if (IS_ERR(op_data))
+               GOTO(out, rc = PTR_ERR(op_data));
+       /**
+        *FIXME choose the start offset of the readdir
+        */
+       op_data->op_stripe_offset = 0;
+       op_data->op_hash_offset = 0;
+       op_data->op_max_pages =
+               ll_i2sbi(dir)->ll_md_brw_size >> PAGE_CACHE_SHIFT;
+
+       for (ent = ll_dir_entry_start(dir, op_data, &page);
+            ent != NULL && !IS_ERR(ent);
+            ent = ll_dir_entry_next(dir, op_data, ent, &page)) {
+               __u64 hash;
+               int namelen;
+               char *name;
+
+               hash = le64_to_cpu(ent->lde_hash);
+               /* The ll_get_dir_page() can return any page containing
+                * the given hash which may be not the start hash. */
+               if (unlikely(hash < op_data->op_hash_offset))
+                       continue;
+
+               namelen = le16_to_cpu(ent->lde_namelen);
+               if (unlikely(namelen == 0))
+                       /*
+                        * skip dummy record.
+                        */
+                       continue;
+
+               name = ent->lde_name;
+               if (name[0] == '.') {
+                       if (namelen == 1)
+                               /*
+                                * skip "."
+                                */
+                               continue;
+                       else if (name[1] == '.' && namelen == 2)
+                               /*
+                                * skip ".."
+                                */
+                               continue;
+                       else
+                               dot_de = 1;
+               } else {
+                       dot_de = 0;
+               }
+
+               if (dot_de && target->name[0] != '.') {
+                       CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
+                              target->len, target->name,
+                              namelen, name);
+                       continue;
+               }
+
+               if (target->len != namelen ||
+                   memcmp(target->name, name, namelen) != 0)
+                       rc = LS_NONE_FIRST_DE;
+               else if (!dot_de)
+                       rc = LS_FIRST_DE;
+               else
+                       rc = LS_FIRST_DOT_DE;
+
+               break;
+       }
         EXIT;
 
+       if (page != NULL) {
+               kunmap(page);
+               page_cache_release(page);
+       }
+       ll_finish_md_op_data(op_data);
 out:
-        ll_dir_chain_fini(&chain);
+       ll_dir_chain_fini(&chain);
         return rc;
 }
 
@@ -1537,28 +1456,28 @@ ll_sai_unplug(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
         } else {
                 struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 
-                sai->sai_miss++;
-                sai->sai_consecutive_miss++;
-                if (sa_low_hit(sai) && thread_is_running(thread)) {
-                        atomic_inc(&sbi->ll_sa_wrong);
-                        CDEBUG(D_READA, "Statahead for dir "DFID" hit "
-                               "ratio too low: hit/miss "LPU64"/"LPU64
-                               ", sent/replied "LPU64"/"LPU64", stopping "
-                               "statahead thread: pid %d\n",
-                               PFID(&lli->lli_fid), sai->sai_hit,
-                               sai->sai_miss, sai->sai_sent,
-                               sai->sai_replied, cfs_curproc_pid());
-                        cfs_spin_lock(&lli->lli_sa_lock);
-                        if (!thread_is_stopped(thread))
-                                thread_set_flags(thread, SVC_STOPPING);
-                        cfs_spin_unlock(&lli->lli_sa_lock);
-                }
-        }
-
-        if (!thread_is_stopped(thread))
-                cfs_waitq_signal(&thread->t_ctl_waitq);
-
-        EXIT;
+               sai->sai_miss++;
+               sai->sai_consecutive_miss++;
+               if (sa_low_hit(sai) && thread_is_running(thread)) {
+                       atomic_inc(&sbi->ll_sa_wrong);
+                       CDEBUG(D_READA, "Statahead for dir "DFID" hit "
+                              "ratio too low: hit/miss "LPU64"/"LPU64
+                              ", sent/replied "LPU64"/"LPU64", stopping "
+                              "statahead thread\n",
+                              PFID(&lli->lli_fid), sai->sai_hit,
+                              sai->sai_miss, sai->sai_sent,
+                              sai->sai_replied);
+                       spin_lock(&lli->lli_sa_lock);
+                       if (!thread_is_stopped(thread))
+                               thread_set_flags(thread, SVC_STOPPING);
+                       spin_unlock(&lli->lli_sa_lock);
+               }
+       }
+
+       if (!thread_is_stopped(thread))
+               wake_up(&thread->t_ctl_waitq);
+
+       EXIT;
 }
 
 /**
@@ -1573,16 +1492,18 @@ ll_sai_unplug(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
                        int only_unplug)
 {
-        struct ll_inode_info     *lli   = ll_i2info(dir);
-        struct ll_statahead_info *sai   = lli->lli_sai;
-        struct dentry            *parent;
-        struct ll_sa_entry       *entry;
-        struct ptlrpc_thread     *thread;
-        struct l_wait_info        lwi   = { 0 };
-        int                       rc    = 0;
-        ENTRY;
-
-        LASSERT(lli->lli_opendir_pid == cfs_curproc_pid());
+       struct ll_inode_info            *lli = ll_i2info(dir);
+       struct ll_statahead_info        *sai = lli->lli_sai;
+       struct dentry                   *parent;
+       struct ll_sa_entry              *entry;
+       struct ptlrpc_thread            *thread;
+       struct l_wait_info               lwi = { 0 };
+       struct task_struct              *task;
+       int                              rc = 0;
+       struct ll_inode_info            *plli;
+       ENTRY;
+
+       LASSERT(lli->lli_opendir_pid == current_pid());
 
         if (sai) {
                 thread = &sai->sai_thread;
@@ -1626,11 +1547,6 @@ int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
                         RETURN(entry ? 1 : -EAGAIN);
                 }
 
-                while (!ll_sa_entry_stated(entry) &&
-                       sai->sai_in_readpage &&
-                       !sa_received_empty(sai))
-                        do_statahead_interpret(sai, entry);
-
                 if (!ll_sa_entry_stated(entry)) {
                         sai->sai_index_wait = entry->se_index;
                         lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(30), NULL,
@@ -1651,27 +1567,43 @@ int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
                         struct lookup_intent it = { .it_op = IT_GETATTR,
                                                     .d.lustre.it_lock_handle =
                                                      entry->se_handle };
-                        struct ll_dentry_data *lld;
-                        __u64 bits;
-
-                        rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
-                                                ll_inode2fid(inode), &bits);
-                        if (rc == 1) {
-                                if ((*dentryp)->d_inode == NULL) {
-                                        *dentryp = ll_find_alias(inode,
-                                                                 *dentryp);
-                                        lld = ll_d2d(*dentryp);
-                                        if (unlikely(lld == NULL))
-                                                ll_dops_init(*dentryp, 1, 1);
+                       __u64 bits;
+
+                       rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
+                                               ll_inode2fid(inode), &bits);
+                       if (rc == 1) {
+                               if ((*dentryp)->d_inode == NULL) {
+                                       struct dentry *alias;
+
+                                       alias = ll_splice_alias(inode,
+                                                               *dentryp);
+                                       if (IS_ERR(alias)) {
+                                               ll_sai_unplug(sai, entry);
+                                               RETURN(PTR_ERR(alias));
+                                       }
+                                       *dentryp = alias;
+                                } else if ((*dentryp)->d_inode != inode) {
+                                        /* revalidate, but inode is recreated */
+                                        CDEBUG(D_READA,
+                                              "%s: stale dentry %.*s inode "
+                                              DFID", statahead inode "DFID
+                                              "\n",
+                                              ll_get_fsname((*dentryp)->d_inode->i_sb, NULL, 0),
+                                              (*dentryp)->d_name.len,
+                                              (*dentryp)->d_name.name,
+                                              PFID(ll_inode2fid((*dentryp)->d_inode)),
+                                              PFID(ll_inode2fid(inode)));
+                                       ll_intent_release(&it);
+                                       ll_sai_unplug(sai, entry);
+                                        RETURN(-ESTALE);
                                 } else {
-                                        LASSERT((*dentryp)->d_inode == inode);
+                                       iput(inode);
+                               }
+                               entry->se_inode = NULL;
 
-                                        ll_dentry_rehash(*dentryp, 0);
-                                        iput(inode);
-                                }
-                                entry->se_inode = NULL;
-
-                                ll_dentry_reset_flags(*dentryp, bits);
+                               if ((bits & MDS_INODELOCK_LOOKUP) &&
+                                   d_lustre_invalid(*dentryp))
+                                       d_lustre_revalidate(*dentryp);
                                 ll_intent_release(&it);
                         }
                 }
@@ -1712,18 +1644,32 @@ int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
                 GOTO(out, rc = -EAGAIN);
         }
 
-        CDEBUG(D_READA, "start statahead thread: [pid %d] [parent %.*s]\n",
-               cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
+       CDEBUG(D_READA, "start statahead thread: sai %p, parent %.*s\n",
+              sai, parent->d_name.len, parent->d_name.name);
 
+       /* The sai buffer already has one reference taken at allocation time,
+        * but as soon as we expose the sai by attaching it to the lli that
+        * default reference can be dropped by another thread calling
+        * ll_stop_statahead. We need to take a local reference to protect
+        * the sai buffer while we intend to access it. */
+        ll_sai_get(sai);
         lli->lli_sai = sai;
-        rc = cfs_create_thread(ll_statahead_thread, parent, 0);
-        thread = &sai->sai_thread;
-        if (rc < 0) {
-                CERROR("can't start ll_sa thread, rc: %d\n", rc);
-                dput(parent);
+
+       plli = ll_i2info(parent->d_inode);
+       task = kthread_run(ll_statahead_thread, parent, "ll_sa_%u",
+                          plli->lli_opendir_pid);
+       thread = &sai->sai_thread;
+       if (IS_ERR(task)) {
+               rc = PTR_ERR(task);
+               CERROR("cannot start ll_sa thread: rc = %d\n", rc);
+               dput(parent);
                 lli->lli_opendir_key = NULL;
                 thread_set_flags(thread, SVC_STOPPED);
+                thread_set_flags(&sai->sai_agl_thread, SVC_STOPPED);
+               /* Drop both our own local reference and the default
+                * reference from allocation time. */
                 ll_sai_put(sai);
+               ll_sai_put(sai);
                 LASSERT(lli->lli_sai == NULL);
                 RETURN(-EAGAIN);
         }
@@ -1731,19 +1677,20 @@ int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
         l_wait_event(thread->t_ctl_waitq,
                      thread_is_running(thread) || thread_is_stopped(thread),
                      &lwi);
+       ll_sai_put(sai);
 
         /*
          * We don't stat-ahead for the first dirent since we are already in
-         * lookup, and -EEXIST also indicates that this is the first dirent.
+         * lookup.
          */
-        RETURN(-EEXIST);
+        RETURN(-EAGAIN);
 
 out:
         if (sai != NULL)
                 OBD_FREE_PTR(sai);
-        cfs_spin_lock(&lli->lli_sa_lock);
-        lli->lli_opendir_key = NULL;
-        lli->lli_opendir_pid = 0;
-        cfs_spin_unlock(&lli->lli_sa_lock);
-        return rc;
+       spin_lock(&lli->lli_sa_lock);
+       lli->lli_opendir_key = NULL;
+       lli->lli_opendir_pid = 0;
+       spin_unlock(&lli->lli_sa_lock);
+       return rc;
 }