Whamcloud - gitweb
LU-1684 ldlm: move ldlm flags not sent through wire to upper 32bits
[fs/lustre-release.git] / lustre / llite / statahead.c
index cb1883b..5cf4b9c 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, 2012, Whamcloud, Inc.
  */
 /*
  * 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
@@ -88,7 +83,7 @@ struct ll_sa_entry {
 };
 
 static unsigned int sai_generation = 0;
-static cfs_spinlock_t sai_generation_lock = CFS_SPIN_LOCK_UNLOCKED;
+static DEFINE_SPINLOCK(sai_generation_lock);
 
 static inline int ll_sa_entry_unlinked(struct ll_sa_entry *entry)
 {
@@ -140,14 +135,42 @@ ll_sa_entry_unhash(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
         cfs_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_has_smd && sai->sai_agl_valid)
+               return 1;
+       return 0;
+}
+
+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)
 {
         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);
 }
 
 /**
@@ -417,6 +440,37 @@ ll_sa_entry_to_stated(struct ll_statahead_info *sai,
         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;
+
+        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);
+}
+
 static struct ll_statahead_info *ll_sai_alloc(void)
 {
         struct ll_statahead_info *sai;
@@ -428,17 +482,24 @@ 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);
+
         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]);
@@ -472,12 +533,13 @@ static void ll_sai_put(struct ll_statahead_info *sai)
                 }
 
                 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);
 
-                LASSERT(thread_is_stopped(&sai->sai_thread));
-
                 if (sai->sai_sent > sai->sai_replied)
                         CDEBUG(D_READA,"statahead for dir "DFID" does not "
                               "finish: [sent:"LPU64"] [replied:"LPU64"]\n",
@@ -495,6 +557,7 @@ static void ll_sai_put(struct ll_statahead_info *sai)
                         do_sai_entry_fini(sai, entry);
 
                 LASSERT(cfs_atomic_read(&sai->sai_cache_count) == 0);
+                LASSERT(agl_list_empty(sai));
 
                 iput(inode);
                 OBD_FREE_PTR(sai);
@@ -503,6 +566,69 @@ static void ll_sai_put(struct ll_statahead_info *sai)
         EXIT;
 }
 
+/* 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 = cfs_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)) {
+                cfs_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();
+        cfs_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 do_statahead_interpret(struct ll_statahead_info *sai,
                                    struct ll_sa_entry *target)
 {
@@ -525,8 +651,7 @@ static void do_statahead_interpret(struct ll_statahead_info *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);
+                entry = sa_first_received_entry(sai);
         }
 
         cfs_atomic_inc(&entry->se_refcount);
@@ -580,6 +705,9 @@ 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:
@@ -689,11 +817,12 @@ 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 +849,7 @@ 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 +874,7 @@ 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 +924,7 @@ 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 +947,9 @@ 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 +962,13 @@ 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 +989,138 @@ 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);
+        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);
+
+        while (1) {
+                l_wait_event(thread->t_ctl_waitq,
+                             !agl_list_empty(sai) ||
+                             !thread_is_running(thread),
+                             &lwi);
+
+                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);
+}
+
+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);
+        cfs_spin_lock(&plli->lli_sa_lock);
         thread_set_flags(thread, SVC_RUNNING);
-        cfs_spin_unlock(&lli->lli_sa_lock);
+        cfs_spin_unlock(&plli->lli_sa_lock);
         cfs_waitq_signal(&thread->t_ctl_waitq);
-        CDEBUG(D_READA, "start doing statahead for %s\n", parent->d_name.name);
 
-        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 l_wait_info lwi = { 0 };
                 struct lu_dirpage *dp;
                 struct lu_dirent  *ent;
 
@@ -899,7 +1129,7 @@ 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 +1181,55 @@ 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);
 
                         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)) {
+                                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;
+                        }
 
+do_it:
                         ll_statahead_one(parent, name, namelen);
                 }
                 pos = le64_to_cpu(dp->ldp_hash_end);
@@ -990,11 +1248,26 @@ keep_de:
                                 while (!sa_received_empty(sai))
                                         do_statahead_interpret(sai, NULL);
 
-                                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;
                         }
+
+                        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.
@@ -1002,9 +1275,8 @@ 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 +1289,41 @@ keep_de:
         EXIT;
 
 out:
+        if (sai->sai_agl_valid) {
+                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);
+        } else {
+                /* Set agl_thread flags anyway. */
+                thread_set_flags(&sai->sai_agl_thread, SVC_STOPPED);
+        }
         ll_dir_chain_fini(&chain);
-        cfs_spin_lock(&lli->lli_sa_lock);
+        cfs_spin_lock(&plli->lli_sa_lock);
         if (!sa_received_empty(sai)) {
                 thread_set_flags(thread, SVC_STOPPING);
-                cfs_spin_unlock(&lli->lli_sa_lock);
+                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(&lli->lli_sa_lock);
+                cfs_spin_lock(&plli->lli_sa_lock);
         }
         thread_set_flags(thread, SVC_STOPPED);
-        cfs_spin_unlock(&lli->lli_sa_lock);
+        cfs_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;
 }
 
@@ -1067,7 +1354,7 @@ void ll_stop_statahead(struct inode *dir, void *key)
                         cfs_spin_unlock(&lli->lli_sa_lock);
                         cfs_waitq_signal(&thread->t_ctl_waitq);
 
-                        CDEBUG(D_READA, "stopping statahead thread, pid %d\n",
+                        CDEBUG(D_READA, "stop statahead thread: [pid %d]\n",
                                cfs_curproc_pid());
                         l_wait_event(thread->t_ctl_waitq,
                                      thread_is_stopped(thread),
@@ -1105,18 +1392,16 @@ 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 +1488,7 @@ 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 +1509,7 @@ 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)
@@ -1355,27 +1639,35 @@ 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);
-
-                                        ll_dentry_rehash(*dentryp, 0);
-                                        iput(inode);
-                                }
-                                entry->se_inode = NULL;
+                                       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 +1708,9 @@ 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 +1719,7 @@ 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);
@@ -1435,9 +1731,9 @@ 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)