Whamcloud - gitweb
LU-3409 llite: silence lockdep warning in ll_md_blocking_ast
[fs/lustre-release.git] / lustre / llite / statahead.c
index cb1883b..a2e48f4 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 */
+       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;
 };
 
 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]);
 }
 
 /*
@@ -133,11 +125,36 @@ 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)
+{
+       return (inode != NULL && S_ISREG(inode->i_mode) && sai->sai_agl_valid);
+}
+
+static inline struct ll_sa_entry *
+sa_first_received_entry(struct ll_statahead_info *sai)
+{
+        return cfs_list_entry(sai->sai_entries_received.next,
+                              struct ll_sa_entry, se_list);
+}
+
+static inline struct ll_inode_info *
+agl_first_entry(struct ll_statahead_info *sai)
+{
+        return cfs_list_entry(sai->sai_entries_agl.next,
+                              struct ll_inode_info, lli_agl_list);
+}
+
+static inline int sa_sent_full(struct ll_statahead_info *sai)
+{
+        return cfs_atomic_read(&sai->sai_cache_count) >= sai->sai_max;
 }
 
 static inline int sa_received_empty(struct ll_statahead_info *sai)
@@ -145,9 +162,9 @@ static inline int sa_received_empty(struct ll_statahead_info *sai)
         return cfs_list_empty(&sai->sai_entries_received);
 }
 
-static inline int sa_not_full(struct ll_statahead_info *sai)
+static inline int agl_list_empty(struct ll_statahead_info *sai)
 {
-        return (cfs_atomic_read(&sai->sai_cache_count) < sai->sai_max);
+        return cfs_list_empty(&sai->sai_entries_agl);
 }
 
 /**
@@ -173,7 +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,
@@ -190,8 +207,8 @@ 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;
 
@@ -229,14 +246,15 @@ ll_sa_entry_alloc(struct ll_statahead_info *sai, __u64 index,
         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);
+       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);
 
-        cfs_atomic_inc(&sai->sai_cache_count);
-        ll_sa_entry_enhash(sai, entry);
+       cfs_atomic_inc(&sai->sai_cache_count);
 
-        RETURN(entry);
+       RETURN(entry);
 }
 
 /*
@@ -271,17 +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);
+                       cfs_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,
@@ -306,37 +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 (cfs_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);
+               cfs_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);
 }
 
 /*
@@ -345,52 +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;
+       struct ll_sa_entry *pos, *next;
 
-        if (entry)
-                do_sai_entry_fini(sai, entry);
-
-        /* 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;
 }
 
 /*
@@ -400,21 +413,52 @@ 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;
+}
+
+/*
+ * Insert inode into the list of sai_entries_agl.
+ */
+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;
+
+       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)
+               cfs_waitq_signal(&sai->sai_agl_thread.t_ctl_waitq);
 }
 
 static struct ll_statahead_info *ll_sai_alloc(void)
@@ -428,20 +472,27 @@ static struct ll_statahead_info *ll_sai_alloc(void)
                 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);
+
+       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;
         cfs_waitq_init(&sai->sai_waitq);
         cfs_waitq_init(&sai->sai_thread.t_ctl_waitq);
-        CFS_INIT_LIST_HEAD(&sai->sai_entries_sent);
+        cfs_waitq_init(&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]);
-                cfs_spin_lock_init(&sai->sai_cache_lock[i]);
+               spin_lock_init(&sai->sai_cache_lock[i]);
         }
         cfs_atomic_set(&sai->sai_cache_count, 0);
 
@@ -467,16 +518,17 @@ static void ll_sai_put(struct ll_statahead_info *sai)
                 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;
-                }
+                       spin_unlock(&lli->lli_sa_lock);
+                       RETURN_EXIT;
+               }
 
-                LASSERT(lli->lli_opendir_key == NULL);
-                lli->lli_sai = NULL;
-                lli->lli_opendir_pid = 0;
-                cfs_spin_unlock(&lli->lli_sa_lock);
+               LASSERT(lli->lli_opendir_key == NULL);
+               LASSERT(thread_is_stopped(&sai->sai_thread));
+               LASSERT(thread_is_stopped(&sai->sai_agl_thread));
 
-                LASSERT(thread_is_stopped(&sai->sai_thread));
+               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 "
@@ -484,17 +536,16 @@ 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));
 
                 iput(inode);
                 OBD_FREE_PTR(sai);
@@ -503,8 +554,70 @@ static void ll_sai_put(struct ll_statahead_info *sai)
         EXIT;
 }
 
-static void do_statahead_interpret(struct ll_statahead_info *sai,
-                                   struct ll_sa_entry *target)
+/* 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)
+{
+        struct ll_inode_info *lli   = ll_i2info(inode);
+        __u64                 index = lli->lli_agl_index;
+        int                   rc;
+        ENTRY;
+
+        LASSERT(cfs_list_empty(&lli->lli_agl_list));
+
+        /* AGL maybe fall behind statahead with one entry */
+        if (is_omitted_entry(sai, index + 1)) {
+                lli->lli_agl_index = 0;
+                iput(inode);
+                RETURN_EXIT;
+        }
+
+        /* Someone is in glimpse (sync or async), do nothing. */
+       rc = down_write_trylock(&lli->lli_glimpse_sem);
+        if (rc == 0) {
+                lli->lli_agl_index = 0;
+                iput(inode);
+                RETURN_EXIT;
+        }
+
+        /*
+         * Someone triggered glimpse within 1 sec before.
+         * 1) The former glimpse succeeded with glimpse lock granted by OST, and
+         *    if the lock is still cached on client, AGL needs to do nothing. If
+         *    it is cancelled by other client, AGL maybe cannot obtaion new lock
+         *    for no glimpse callback triggered by AGL.
+         * 2) The former glimpse succeeded, but OST did not grant glimpse lock.
+         *    Under such case, it is quite possible that the OST will not grant
+         *    glimpse lock for AGL also.
+         * 3) The former glimpse failed, compared with other two cases, it is
+         *    relative rare. AGL can ignore such case, and it will not muchly
+         *    affect the performance.
+         */
+        if (lli->lli_glimpse_time != 0 &&
+            cfs_time_before(cfs_time_shift(-1), lli->lli_glimpse_time)) {
+               up_write(&lli->lli_glimpse_sem);
+                lli->lli_agl_index = 0;
+                iput(inode);
+                RETURN_EXIT;
+        }
+
+        CDEBUG(D_READA, "Handling (init) async glimpse: inode = "
+               DFID", idx = "LPU64"\n", PFID(&lli->lli_fid), index);
+
+        cl_agl(inode);
+        lli->lli_agl_index = 0;
+        lli->lli_glimpse_time = cfs_time_current();
+       up_write(&lli->lli_glimpse_sem);
+
+        CDEBUG(D_READA, "Handled (init) async glimpse: inode= "
+               DFID", idx = "LPU64", rc = %d\n",
+               PFID(&lli->lli_fid), index, rc);
+
+        iput(inode);
+
+        EXIT;
+}
+
+static void ll_post_statahead(struct ll_statahead_info *sai)
 {
         struct inode           *dir   = sai->sai_inode;
         struct inode           *child;
@@ -517,21 +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 = cfs_list_entry(sai->sai_entries_received.next,
-                                       struct ll_sa_entry, se_list);
-        }
-
-        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);
+       cfs_atomic_inc(&entry->se_refcount);
+       cfs_list_del_init(&entry->se_list);
+       spin_unlock(&lli->lli_sa_lock);
 
         LASSERT(entry->se_handle != 0);
 
@@ -566,11 +673,11 @@ 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);
 
@@ -580,6 +687,9 @@ static void do_statahead_interpret(struct ll_statahead_info *sai,
 
         entry->se_inode = child;
 
+        if (agl_should_run(sai, child))
+                ll_agl_add(sai, child, entry->se_index);
+
         EXIT;
 
 out:
@@ -587,8 +697,9 @@ out:
          * 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)
+       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)
                 cfs_waitq_signal(&sai->sai_waitq);
         ll_sa_entry_put(sai, entry);
 }
@@ -607,52 +718,49 @@ 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)
+                       cfs_waitq_signal(&sai->sai_thread.t_ctl_waitq);
         }
 
         EXIT;
@@ -689,11 +797,12 @@ static void sa_args_fini(struct md_enqueue_info *minfo,
  * "md_intent_getattr_async".
  */
 static int sa_args_init(struct inode *dir, struct inode *child,
-                        struct qstr *qstr, struct md_enqueue_info **pmi,
+                        struct ll_sa_entry *entry, struct md_enqueue_info **pmi,
                         struct ldlm_enqueue_info **pei,
                         struct obd_capa **pcapa)
 {
-        struct ll_inode_info     *lli = ll_i2info(dir);
+        struct qstr              *qstr = &entry->se_qstr;
+        struct ll_inode_info     *lli  = ll_i2info(dir);
         struct md_enqueue_info   *minfo;
         struct ldlm_enqueue_info *einfo;
         struct md_op_data        *op_data;
@@ -720,7 +829,7 @@ static int sa_args_init(struct inode *dir, struct inode *child,
         minfo->mi_dir = igrab(dir);
         minfo->mi_cb = ll_statahead_interpret;
         minfo->mi_generation = lli->lli_sai->sai_generation;
-        minfo->mi_cbdata = lli->lli_sai->sai_index;
+        minfo->mi_cbdata = entry->se_index;
 
         einfo->ei_type   = LDLM_IBITS;
         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
@@ -745,7 +854,7 @@ static int do_sa_lookup(struct inode *dir, struct ll_sa_entry *entry)
         int                       rc;
         ENTRY;
 
-        rc = sa_args_init(dir, NULL, &entry->se_qstr, &minfo, &einfo, capas);
+        rc = sa_args_init(dir, NULL, entry, &minfo, &einfo, capas);
         if (rc)
                 RETURN(rc);
 
@@ -795,7 +904,7 @@ static int do_sa_revalidate(struct inode *dir, struct ll_sa_entry *entry,
                 RETURN(1);
         }
 
-        rc = sa_args_init(dir, inode, &entry->se_qstr, &minfo, &einfo, capas);
+        rc = sa_args_init(dir, inode, entry, &minfo, &einfo, capas);
         if (rc) {
                 entry->se_inode = NULL;
                 iput(inode);
@@ -818,9 +927,9 @@ static int do_sa_revalidate(struct inode *dir, struct ll_sa_entry *entry,
 static void ll_statahead_one(struct dentry *parent, const char* entry_name,
                              int entry_name_len)
 {
-        struct inode             *dir = parent->d_inode;
-        struct ll_inode_info     *lli = ll_i2info(dir);
-        struct ll_statahead_info *sai = lli->lli_sai;
+        struct inode             *dir    = parent->d_inode;
+        struct ll_inode_info     *lli    = ll_i2info(dir);
+        struct ll_statahead_info *sai    = lli->lli_sai;
         struct dentry            *dentry = NULL;
         struct ll_sa_entry       *entry;
         int                       rc;
@@ -833,10 +942,13 @@ static void ll_statahead_one(struct dentry *parent, const char* entry_name,
                 RETURN_EXIT;
 
         dentry = d_lookup(parent, &entry->se_qstr);
-        if (!dentry)
+        if (!dentry) {
                 rc = do_sa_lookup(dir, entry);
-        else
+        } else {
                 rc = do_sa_revalidate(dir, entry, dentry);
+                if (rc == 1 && agl_should_run(sai, dentry->d_inode))
+                        ll_agl_add(sai, dentry->d_inode, entry->se_index);
+        }
 
         if (dentry != NULL)
                 dput(dentry);
@@ -857,40 +969,138 @@ static void ll_statahead_one(struct dentry *parent, const char* entry_name,
         EXIT;
 }
 
+static int ll_agl_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_agl_thread;
+        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);
+       spin_lock(&plli->lli_agl_lock);
+       sai->sai_agl_valid = 1;
+       thread_set_flags(thread, SVC_RUNNING);
+       spin_unlock(&plli->lli_agl_lock);
+        cfs_waitq_signal(&thread->t_ctl_waitq);
+
+        while (1) {
+                l_wait_event(thread->t_ctl_waitq,
+                             !agl_list_empty(sai) ||
+                             !thread_is_running(thread),
+                             &lwi);
+
+                if (!thread_is_running(thread))
+                        break;
+
+               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);
+       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);
+}
+
+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);
+                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     *lli = ll_i2info(dir);
-        struct ll_sb_info        *sbi = ll_i2sbi(dir);
-        struct ll_statahead_info *sai = ll_sai_get(lli->lli_sai);
+        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;
         struct page              *page;
-        __u64                     pos = 0;
-        int                       first = 0;
-        int                       rc = 0;
+        __u64                     pos    = 0;
+        int                       first  = 0;
+        int                       rc     = 0;
         struct ll_dir_chain       chain;
+        struct l_wait_info        lwi    = { 0 };
         ENTRY;
 
         {
                 char pname[16];
-                snprintf(pname, 15, "ll_sa_%u", lli->lli_opendir_pid);
+                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(&lli->lli_sa_lock);
-        thread_set_flags(thread, SVC_RUNNING);
-        cfs_spin_unlock(&lli->lli_sa_lock);
-        cfs_waitq_signal(&thread->t_ctl_waitq);
-        CDEBUG(D_READA, "start doing statahead for %s\n", parent->d_name.name);
+       spin_lock(&plli->lli_sa_lock);
+       thread_set_flags(thread, SVC_RUNNING);
+       spin_unlock(&plli->lli_sa_lock);
+       cfs_waitq_signal(&thread->t_ctl_waitq);
 
-        lli->lli_sa_pos = 0;
-        ll_dir_chain_init(&chain);
-        page = ll_get_dir_page(NULL, dir, pos, &chain);
+       ll_dir_chain_init(&chain);
+       page = ll_get_dir_page(dir, pos, &chain);
 
         while (1) {
-                struct l_wait_info lwi = { 0 };
                 struct lu_dirpage *dp;
                 struct lu_dirent  *ent;
 
@@ -899,7 +1109,7 @@ static int ll_statahead_thread(void *arg)
                         CDEBUG(D_READA, "error reading dir "DFID" at "LPU64
                                "/"LPU64": [rc %d] [parent %u]\n",
                                PFID(ll_inode2fid(dir)), pos, sai->sai_index,
-                               rc, lli->lli_opendir_pid);
+                               rc, plli->lli_opendir_pid);
                         GOTO(out, rc);
                 }
 
@@ -951,27 +1161,55 @@ static int ll_statahead_thread(void *arg)
                         if (unlikely(++first == 1))
                                 continue;
 
-keep_de:
+keep_it:
                         l_wait_event(thread->t_ctl_waitq,
-                                     sa_not_full(sai) ||
+                                     !sa_sent_full(sai) ||
                                      !sa_received_empty(sai) ||
+                                     !agl_list_empty(sai) ||
                                      !thread_is_running(thread),
                                      &lwi);
 
+interpret_it:
                         while (!sa_received_empty(sai))
-                                do_statahead_interpret(sai, NULL);
+                               ll_post_statahead(sai);
 
                         if (unlikely(!thread_is_running(thread))) {
                                 ll_release_page(page, 0);
-                                GOTO(out, rc);
+                                GOTO(out, rc = 0);
                         }
 
-                        if (!sa_not_full(sai))
-                                /*
-                                 * do not skip the current de.
-                                 */
-                                goto keep_de;
+                        /* 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);
+
+                                        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;
+
+                                       spin_lock(&plli->lli_agl_lock);
+                               }
+                               spin_unlock(&plli->lli_agl_lock);
+
+                                goto keep_it;
+                        }
 
+do_it:
                         ll_statahead_one(parent, name, namelen);
                 }
                 pos = le64_to_cpu(dp->ldp_hash_end);
@@ -988,13 +1226,28 @@ keep_de:
                                              &lwi);
 
                                 while (!sa_received_empty(sai))
-                                        do_statahead_interpret(sai, NULL);
+                                       ll_post_statahead(sai);
 
-                                if ((sai->sai_sent == sai->sai_replied &&
-                                     sa_received_empty(sai)) ||
-                                    !thread_is_running(thread))
+                                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);
+
+                        GOTO(out, rc = 0);
                 } else if (1) {
                         /*
                          * chain is exhausted.
@@ -1002,9 +1255,8 @@ keep_de:
                          */
                         ll_release_page(page, le32_to_cpu(dp->ldp_flags) &
                                               LDF_COLLIDE);
-                        lli->lli_sa_pos = pos;
                         sai->sai_in_readpage = 1;
-                        page = ll_get_dir_page(NULL, dir, pos, &chain);
+                       page = ll_get_dir_page(dir, pos, &chain);
                         sai->sai_in_readpage = 0;
                 } else {
                         LASSERT(le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
@@ -1017,26 +1269,41 @@ keep_de:
         EXIT;
 
 out:
-        ll_dir_chain_fini(&chain);
-        cfs_spin_lock(&lli->lli_sa_lock);
-        if (!sa_received_empty(sai)) {
-                thread_set_flags(thread, SVC_STOPPING);
-                cfs_spin_unlock(&lli->lli_sa_lock);
-
-                /* To release the resources held by received entries. */
-                while (!sa_received_empty(sai))
-                        do_statahead_interpret(sai, NULL);
-
-                cfs_spin_lock(&lli->lli_sa_lock);
+        if (sai->sai_agl_valid) {
+               spin_lock(&plli->lli_agl_lock);
+               thread_set_flags(agl_thread, SVC_STOPPING);
+               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);
+        } else {
+                /* Set agl_thread flags anyway. */
+                thread_set_flags(&sai->sai_agl_thread, SVC_STOPPED);
         }
-        thread_set_flags(thread, SVC_STOPPED);
-        cfs_spin_unlock(&lli->lli_sa_lock);
+        ll_dir_chain_fini(&chain);
+       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);
         cfs_waitq_signal(&sai->sai_waitq);
         cfs_waitq_signal(&thread->t_ctl_waitq);
         ll_sai_put(sai);
         dput(parent);
-        CDEBUG(D_READA, "statahead thread stopped, pid %d\n",
-               cfs_curproc_pid());
+        CDEBUG(D_READA, "statahead thread stopped: [pid %d] [parent %.*s]\n",
+               cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
         return rc;
 }
 
@@ -1045,14 +1312,14 @@ 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;
         }
 
@@ -1064,28 +1331,28 @@ 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, "stopping 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);
+                       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 {
+                       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 {
@@ -1105,18 +1372,16 @@ 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;
+        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);
+       page = ll_get_dir_page(dir, pos, &chain);
 
         while (1) {
                 struct lu_dirpage *dp;
@@ -1203,8 +1468,7 @@ static int is_first_dirent(struct inode *dir, struct dentry *dentry)
                          */
                         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);
+                       page = ll_get_dir_page(dir, pos, &chain);
                 } else {
                         /*
                          * go into overflow page.
@@ -1225,7 +1489,7 @@ ll_sai_unplug(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 {
         struct ptlrpc_thread *thread = &sai->sai_thread;
         struct ll_sb_info    *sbi    = ll_i2sbi(sai->sai_inode);
-        int                  hit;
+        int                   hit;
         ENTRY;
 
         if (entry != NULL && entry->se_stat == SA_ENTRY_SUCC)
@@ -1252,17 +1516,17 @@ ll_sai_unplug(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
                                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);
-                }
-        }
+                       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))
-                cfs_waitq_signal(&thread->t_ctl_waitq);
+       if (!thread_is_stopped(thread))
+               cfs_waitq_signal(&thread->t_ctl_waitq);
 
-        EXIT;
+       EXIT;
 }
 
 /**
@@ -1330,10 +1594,11 @@ int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
                         RETURN(entry ? 1 : -EAGAIN);
                 }
 
+               /* if statahead is busy in readdir, help it do post-work */
                 while (!ll_sa_entry_stated(entry) &&
                        sai->sai_in_readpage &&
                        !sa_received_empty(sai))
-                        do_statahead_interpret(sai, entry);
+                       ll_post_statahead(sai);
 
                 if (!ll_sa_entry_stated(entry)) {
                         sai->sai_index_wait = entry->se_index;
@@ -1355,27 +1620,35 @@ 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) {
+                                       *dentryp = ll_splice_alias(inode,
+                                                                  *dentryp);
+                                } else if ((*dentryp)->d_inode != inode) {
+                                        /* revalidate, but inode is recreated */
+                                        CDEBUG(D_READA,
+                                              "stale dentry %.*s inode %lu/%u, "
+                                              "statahead inode %lu/%u\n",
+                                              (*dentryp)->d_name.len,
+                                              (*dentryp)->d_name.name,
+                                              (*dentryp)->d_inode->i_ino,
+                                              (*dentryp)->d_inode->i_generation,
+                                              inode->i_ino,
+                                              inode->i_generation);
+                                        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);
                         }
                 }
@@ -1416,6 +1689,9 @@ 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);
+
         lli->lli_sai = sai;
         rc = cfs_create_thread(ll_statahead_thread, parent, 0);
         thread = &sai->sai_thread;
@@ -1424,6 +1700,7 @@ int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
                 dput(parent);
                 lli->lli_opendir_key = NULL;
                 thread_set_flags(thread, SVC_STOPPED);
+                thread_set_flags(&sai->sai_agl_thread, SVC_STOPPED);
                 ll_sai_put(sai);
                 LASSERT(lli->lli_sai == NULL);
                 RETURN(-EAGAIN);
@@ -1435,16 +1712,16 @@ int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
 
         /*
          * 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;
 }