Whamcloud - gitweb
LU-5010 llite: disable readahead optimization
[fs/lustre-release.git] / lustre / llite / rw.c
index df40ae6..355d07e 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.
  * GPL HEADER END
  */
 /*
- * Copyright  2008 Sun Microsystems, Inc. All rights reserved
+ * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2013, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
  * Lustre Lite I/O page cache routines shared by different kernel revs
  */
 
-#include <linux/autoconf.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/string.h>
 #include <linux/stat.h>
 #include <linux/errno.h>
-#include <linux/smp_lock.h>
 #include <linux/unistd.h>
-#include <linux/version.h>
-#include <asm/system.h>
+#include <linux/writeback.h>
 #include <asm/uaccess.h>
 
 #include <linux/fs.h>
 #include <asm/uaccess.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
-#include <linux/smp_lock.h>
 /* current_is_kswapd() */
 #include <linux/swap.h>
 
 #define DEBUG_SUBSYSTEM S_LLITE
 
-//#include <lustre_mdc.h>
 #include <lustre_lite.h>
 #include <obd_cksum.h>
 #include "llite_internal.h"
 #include <linux/lustre_compat25.h>
 
-/* this isn't where truncate starts.   roughly:
- * sys_truncate->ll_setattr_raw->vmtruncate->ll_truncate. setattr_raw grabs
- * DLM lock on [size, EOF], i_mutex, ->lli_size_sem, and WRITE_I_ALLOC_SEM to
- * avoid races.
- *
- * must be called under ->lli_size_sem */
-void ll_truncate(struct inode *inode)
-{
-        struct ll_inode_info *lli = ll_i2info(inode);
-        ENTRY;
-
-        CDEBUG(D_VFSTRACE, "VFS Op:inode=%lu/%u(%p) to %Lu\n",inode->i_ino,
-               inode->i_generation, inode, i_size_read(inode));
-
-        ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_TRUNC, 1);
-        if (lli->lli_size_sem_owner == cfs_current()) {
-                LASSERT_SEM_LOCKED(&lli->lli_size_sem);
-                ll_inode_size_unlock(inode, 0);
-        }
-
-        EXIT;
-        return;
-} /* ll_truncate */
-
 /**
  * Finalizes cl-data before exiting typical address_space operation. Dual to
  * ll_cl_init().
  */
-static void ll_cl_fini(struct ll_cl_context *lcc)
+void ll_cl_fini(struct ll_cl_context *lcc)
 {
         struct lu_env  *env  = lcc->lcc_env;
         struct cl_io   *io   = lcc->lcc_io;
@@ -109,12 +80,6 @@ static void ll_cl_fini(struct ll_cl_context *lcc)
                 cl_page_put(env, page);
         }
 
-        if (io && lcc->lcc_created) {
-                cl_io_end(env, io);
-                cl_io_unlock(env, io);
-                cl_io_iter_fini(env, io);
-                cl_io_fini(env, io);
-        }
         cl_env_put(env, &lcc->lcc_refcheck);
 }
 
@@ -122,8 +87,7 @@ static void ll_cl_fini(struct ll_cl_context *lcc)
  * Initializes common cl-data at the typical address_space operation entry
  * point.
  */
-static struct ll_cl_context *ll_cl_init(struct file *file,
-                                        struct page *vmpage, int create)
+struct ll_cl_context *ll_cl_init(struct file *file, struct page *vmpage)
 {
         struct ll_cl_context *lcc;
         struct lu_env    *env;
@@ -134,8 +98,8 @@ static struct ll_cl_context *ll_cl_init(struct file *file,
         int refcheck;
         int result = 0;
 
-        clob = ll_i2info(vmpage->mapping->host)->lli_clob;
-        LASSERT(clob != NULL);
+       clob = ll_i2info(file->f_dentry->d_inode)->lli_clob;
+       LASSERT(clob != NULL);
 
         env = cl_env_get(&refcheck);
         if (IS_ERR(env))
@@ -149,52 +113,10 @@ static struct ll_cl_context *ll_cl_init(struct file *file,
 
         cio = ccc_env_io(env);
         io = cio->cui_cl.cis_io;
-        if (io == NULL && create) {
-                struct vvp_io *vio;
-                loff_t pos;
-
-                /*
-                 * Loop-back driver calls ->prepare_write() and ->sendfile()
-                 * methods directly, bypassing file system ->write() operation,
-                 * so cl_io has to be created here.
-                 */
-
-                io = &ccc_env_info(env)->cti_io;
-                vio = vvp_env_io(env);
-                ll_io_init(io, file, 1);
-
-                /* No lock at all for this kind of IO - we can't do it because
-                 * we have held page lock, it would cause deadlock.
-                 * XXX: This causes poor performance to loop device - One page
-                 *      per RPC.
-                 *      In order to get better performance, users should use
-                 *      lloop driver instead.
-                 */
-                io->ci_lockreq = CILR_NEVER;
-
-                pos = (vmpage->index << CFS_PAGE_SHIFT);
-
-                /* Create a temp IO to serve write. */
-                result = cl_io_rw_init(env, io, CIT_WRITE, pos, CFS_PAGE_SIZE);
-                if (result == 0) {
-                        cio->cui_fd = LUSTRE_FPRIVATE(file);
-                        cio->cui_iov = NULL;
-                        cio->cui_nrsegs = 0;
-                        result = cl_io_iter_init(env, io);
-                        if (result == 0) {
-                                result = cl_io_lock(env, io);
-                                if (result == 0)
-                                        result = cl_io_start(env, io);
-                        }
-                } else
-                        result = io->ci_result;
-                lcc->lcc_created = 1;
-        }
-
         lcc->lcc_io = io;
-        if (io == NULL)
-                result = -EIO;
-        if (result == 0) {
+       if (io == NULL)
+               result = -EIO;
+       if (result == 0 && vmpage != NULL) {
                 struct cl_page   *page;
 
                 LASSERT(io != NULL);
@@ -214,107 +136,9 @@ static struct ll_cl_context *ll_cl_init(struct file *file,
                 lcc = ERR_PTR(result);
         }
 
-        CDEBUG(D_VFSTRACE, "%lu@"DFID" -> %i %p %p\n",
-               vmpage->index, PFID(lu_object_fid(&clob->co_lu)), result,
-               env, io);
-        return lcc;
-}
-
-static struct ll_cl_context *ll_cl_get(void)
-{
-        struct ll_cl_context *lcc;
-        struct lu_env *env;
-        int refcheck;
-
-        env = cl_env_get(&refcheck);
-        LASSERT(!IS_ERR(env));
-        lcc = &vvp_env_info(env)->vti_io_ctx;
-        LASSERT(env == lcc->lcc_env);
-        LASSERT(current == lcc->lcc_cookie);
-        cl_env_put(env, &refcheck);
-
-        /* env has got in ll_cl_init, so it is still usable. */
         return lcc;
 }
 
-/**
- * ->prepare_write() address space operation called by generic_file_write()
- * for every page during write.
- */
-int ll_prepare_write(struct file *file, struct page *vmpage, unsigned from,
-                     unsigned to)
-{
-        struct ll_cl_context *lcc;
-        int result;
-        ENTRY;
-
-        lcc = ll_cl_init(file, vmpage, 1);
-        if (!IS_ERR(lcc)) {
-                struct lu_env  *env = lcc->lcc_env;
-                struct cl_io   *io  = lcc->lcc_io;
-                struct cl_page *page = lcc->lcc_page;
-
-                cl_page_assume(env, io, page);
-                if (cl_io_is_append(io)) {
-                        struct cl_object   *obj   = io->ci_obj;
-                        struct inode       *inode = ccc_object_inode(obj);
-                        /**
-                         * In VFS file->page write loop, for appending, the
-                         * write offset might be reset according to the new
-                         * file size before holding i_mutex. So crw_pos should
-                         * be reset here. BUG:17711.
-                         */
-                        io->u.ci_wr.wr.crw_pos = i_size_read(inode);
-                }
-                result = cl_io_prepare_write(env, io, page, from, to);
-                if (result == 0) {
-                        /*
-                         * Add a reference, so that page is not evicted from
-                         * the cache until ->commit_write() is called.
-                         */
-                        cl_page_get(page);
-                        lu_ref_add(&page->cp_reference, "prepare_write",
-                                   cfs_current());
-                } else {
-                        cl_page_unassume(env, io, page);
-                        ll_cl_fini(lcc);
-                }
-                /* returning 0 in prepare assumes commit must be called
-                 * afterwards */
-        } else {
-                result = PTR_ERR(lcc);
-        }
-        RETURN(result);
-}
-
-int ll_commit_write(struct file *file, struct page *vmpage, unsigned from,
-                    unsigned to)
-{
-        struct ll_cl_context *lcc;
-        struct lu_env    *env;
-        struct cl_io     *io;
-        struct cl_page   *page;
-        int result;
-        ENTRY;
-
-        lcc  = ll_cl_get();
-        env  = lcc->lcc_env;
-        page = lcc->lcc_page;
-        io   = lcc->lcc_io;
-
-        LASSERT(cl_page_is_owned(page, io));
-        result = cl_io_commit_write(env, io, page, from, to);
-        if (cl_page_is_owned(page, io))
-                cl_page_unassume(env, io, page);
-        /*
-         * Release reference acquired by cl_io_prepare_write().
-         */
-        lu_ref_del(&page->cp_reference, "prepare_write", cfs_current());
-        cl_page_put(env, page);
-        ll_cl_fini(lcc);
-        RETURN(result);
-}
-
 struct obd_capa *cl_capa_lookup(struct inode *inode, enum cl_req_type crt)
 {
         __u64 opc;
@@ -325,43 +149,75 @@ struct obd_capa *cl_capa_lookup(struct inode *inode, enum cl_req_type crt)
 
 static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which);
 
-/* WARNING: This algorithm is used to reduce the contention on
- * sbi->ll_lock. It should work well if the ra_max_pages is much
- * greater than the single file's read-ahead window.
+/**
+ * Get readahead pages from the filesystem readahead pool of the client for a
+ * thread.
  *
- * TODO: There may exist a `global sync problem' in this implementation.
- * Considering the global ra window is 100M, and each file's ra window is 10M,
- * there are over 10 files trying to get its ra budget and reach
- * ll_ra_count_get at the exactly same time. All of them will get a zero ra
- * window, although the global window is 100M. -jay
- */
-static unsigned long ll_ra_count_get(struct ll_sb_info *sbi, unsigned long len)
+ * /param sbi superblock for filesystem readahead state ll_ra_info
+ * /param ria per-thread readahead state
+ * /param pages number of pages requested for readahead for the thread.
+ *
+ * WARNING: This algorithm is used to reduce contention on sbi->ll_lock.
+ * It should work well if the ra_max_pages is much greater than the single
+ * file's read-ahead window, and not too many threads contending for
+ * these readahead pages.
+ *
+ * TODO: There may be a 'global sync problem' if many threads are trying
+ * to get an ra budget that is larger than the remaining readahead pages
+ * and reach here at exactly the same time. They will compute /a ret to
+ * consume the remaining pages, but will fail at atomic_add_return() and
+ * get a zero ra window, although there is still ra space remaining. - Jay */
+
+static unsigned long ll_ra_count_get(struct ll_sb_info *sbi,
+                                    struct ra_io_arg *ria,
+                                    unsigned long pages, unsigned long min)
 {
         struct ll_ra_info *ra = &sbi->ll_ra_info;
-        unsigned long ret;
+        long ret;
         ENTRY;
 
-        /**
-         * If read-ahead pages left are less than 1M, do not do read-ahead,
+        /* If read-ahead pages left are less than 1M, do not do read-ahead,
          * otherwise it will form small read RPC(< 1M), which hurt server
-         * performance a lot.
-         */
-        ret = min(ra->ra_max_pages - cfs_atomic_read(&ra->ra_cur_pages), len);
-        if ((int)ret < 0 || ret < min((unsigned long)PTLRPC_MAX_BRW_PAGES, len))
+         * performance a lot. */
+       ret = min(ra->ra_max_pages - atomic_read(&ra->ra_cur_pages), pages);
+        if (ret < 0 || ret < min_t(long, PTLRPC_MAX_BRW_PAGES, pages))
                 GOTO(out, ret = 0);
 
-        if (cfs_atomic_add_return(ret, &ra->ra_cur_pages) > ra->ra_max_pages) {
-                cfs_atomic_sub(ret, &ra->ra_cur_pages);
-                ret = 0;
+        /* If the non-strided (ria_pages == 0) readahead window
+         * (ria_start + ret) has grown across an RPC boundary, then trim
+         * readahead size by the amount beyond the RPC so it ends on an
+         * RPC boundary. If the readahead window is already ending on
+         * an RPC boundary (beyond_rpc == 0), or smaller than a full
+         * RPC (beyond_rpc < ret) the readahead size is unchanged.
+         * The (beyond_rpc != 0) check is skipped since the conditional
+         * branch is more expensive than subtracting zero from the result.
+         *
+         * Strided read is left unaligned to avoid small fragments beyond
+         * the RPC boundary from needing an extra read RPC. */
+        if (ria->ria_pages == 0) {
+                long beyond_rpc = (ria->ria_start + ret) % PTLRPC_MAX_BRW_PAGES;
+                if (/* beyond_rpc != 0 && */ beyond_rpc < ret)
+                        ret -= beyond_rpc;
         }
+
+       if (atomic_add_return(ret, &ra->ra_cur_pages) > ra->ra_max_pages) {
+               atomic_sub(ret, &ra->ra_cur_pages);
+               ret = 0;
+       }
+
 out:
-        RETURN(ret);
+       if (ret < min) {
+               /* override ra limit for maximum performance */
+               atomic_add(min - ret, &ra->ra_cur_pages);
+               ret = min;
+       }
+       RETURN(ret);
 }
 
 void ll_ra_count_put(struct ll_sb_info *sbi, unsigned long len)
 {
-        struct ll_ra_info *ra = &sbi->ll_ra_info;
-        cfs_atomic_sub(len, &ra->ra_cur_pages);
+       struct ll_ra_info *ra = &sbi->ll_ra_info;
+       atomic_sub(len, &ra->ra_cur_pages);
 }
 
 static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which)
@@ -370,10 +226,10 @@ static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which)
         lprocfs_counter_incr(sbi->ll_ra_stats, which);
 }
 
-void ll_ra_stats_inc(struct address_space *mapping, enum ra_stat which)
+void ll_ra_stats_inc(struct inode *inode, enum ra_stat which)
 {
-        struct ll_sb_info *sbi = ll_i2sbi(mapping->host);
-        ll_ra_stats_inc_sbi(sbi, which);
+       struct ll_sb_info *sbi = ll_i2sbi(inode);
+       ll_ra_stats_inc_sbi(sbi, which);
 }
 
 #define RAS_CDEBUG(ras) \
@@ -410,36 +266,36 @@ static struct ll_readahead_state *ll_ras_get(struct file *f)
 
 void ll_ra_read_in(struct file *f, struct ll_ra_read *rar)
 {
-        struct ll_readahead_state *ras;
+       struct ll_readahead_state *ras;
 
-        ras = ll_ras_get(f);
+       ras = ll_ras_get(f);
 
-        cfs_spin_lock(&ras->ras_lock);
-        ras->ras_requests++;
-        ras->ras_request_index = 0;
-        ras->ras_consecutive_requests++;
-        rar->lrr_reader = current;
+       spin_lock(&ras->ras_lock);
+       ras->ras_requests++;
+       ras->ras_request_index = 0;
+       ras->ras_consecutive_requests++;
+       rar->lrr_reader = current;
 
-        cfs_list_add(&rar->lrr_linkage, &ras->ras_read_beads);
-        cfs_spin_unlock(&ras->ras_lock);
+       list_add(&rar->lrr_linkage, &ras->ras_read_beads);
+       spin_unlock(&ras->ras_lock);
 }
 
 void ll_ra_read_ex(struct file *f, struct ll_ra_read *rar)
 {
-        struct ll_readahead_state *ras;
+       struct ll_readahead_state *ras;
 
-        ras = ll_ras_get(f);
+       ras = ll_ras_get(f);
 
-        cfs_spin_lock(&ras->ras_lock);
-        cfs_list_del_init(&rar->lrr_linkage);
-        cfs_spin_unlock(&ras->ras_lock);
+       spin_lock(&ras->ras_lock);
+       list_del_init(&rar->lrr_linkage);
+       spin_unlock(&ras->ras_lock);
 }
 
 static struct ll_ra_read *ll_ra_read_get_locked(struct ll_readahead_state *ras)
 {
         struct ll_ra_read *scan;
 
-        cfs_list_for_each_entry(scan, &ras->ras_read_beads, lrr_linkage) {
+       list_for_each_entry(scan, &ras->ras_read_beads, lrr_linkage) {
                 if (scan->lrr_reader == current)
                         return scan;
         }
@@ -448,47 +304,55 @@ static struct ll_ra_read *ll_ra_read_get_locked(struct ll_readahead_state *ras)
 
 struct ll_ra_read *ll_ra_read_get(struct file *f)
 {
-        struct ll_readahead_state *ras;
-        struct ll_ra_read         *bead;
+       struct ll_readahead_state *ras;
+       struct ll_ra_read         *bead;
 
-        ras = ll_ras_get(f);
+       ras = ll_ras_get(f);
 
-        cfs_spin_lock(&ras->ras_lock);
-        bead = ll_ra_read_get_locked(ras);
-        cfs_spin_unlock(&ras->ras_lock);
-        return bead;
+       spin_lock(&ras->ras_lock);
+       bead = ll_ra_read_get_locked(ras);
+       spin_unlock(&ras->ras_lock);
+       return bead;
 }
 
 static int cl_read_ahead_page(const struct lu_env *env, struct cl_io *io,
-                              struct cl_page_list *queue, struct cl_page *page,
-                              struct page *vmpage)
+                             struct cl_page_list *queue, struct cl_page *page,
+                             struct cl_object *clob, pgoff_t *max_index)
 {
-        struct ccc_page *cp;
-        int              rc;
-
-        ENTRY;
-
-        rc = 0;
-        cl_page_assume(env, io, page);
-        lu_ref_add(&page->cp_reference, "ra", cfs_current());
-        cp = cl2ccc_page(cl_page_at(page, &vvp_device_type));
-        if (!cp->cpg_defer_uptodate && !Page_Uptodate(vmpage)) {
-                rc = cl_page_is_under_lock(env, io, page);
-                if (rc == -EBUSY) {
-                        cp->cpg_defer_uptodate = 1;
-                        cp->cpg_ra_used = 0;
-                        cl_page_list_add(queue, page);
-                        rc = 1;
-                } else {
-                        cl_page_delete(env, page);
-                        rc = -ENOLCK;
-                }
-        } else
-                /* skip completed pages */
-                cl_page_unassume(env, io, page);
-        lu_ref_del(&page->cp_reference, "ra", cfs_current());
-        cl_page_put(env, page);
-        RETURN(rc);
+       struct page *vmpage = page->cp_vmpage;
+       struct ccc_page *cp;
+       int              rc;
+
+       ENTRY;
+
+       rc = 0;
+       cl_page_assume(env, io, page);
+       lu_ref_add(&page->cp_reference, "ra", current);
+       cp = cl2ccc_page(cl_object_page_slice(clob, page));
+       if (!cp->cpg_defer_uptodate && !PageUptodate(vmpage)) {
+               CDEBUG(D_READA, "page index %lu, max_index: %lu\n",
+                      ccc_index(cp), *max_index);
+               /* Disable the optimization on prefetching maximum readahead
+                * index because there is a race with lock cancellation. This
+                * optimization will be revived later.
+                * if (*max_index == 0 || ccc_index(cp) > *max_index) */
+               rc = cl_page_is_under_lock(env, io, page, max_index);
+               if (rc == 0) {
+                       cp->cpg_defer_uptodate = 1;
+                       cp->cpg_ra_used = 0;
+                       cl_page_list_add(queue, page);
+                       rc = 1;
+               } else {
+                       cl_page_discard(env, io, page);
+                       rc = -ENOLCK;
+               }
+       } else {
+               /* skip completed pages */
+               cl_page_unassume(env, io, page);
+       }
+       lu_ref_del(&page->cp_reference, "ra", current);
+       cl_page_put(env, page);
+       RETURN(rc);
 }
 
 /**
@@ -502,11 +366,12 @@ static int cl_read_ahead_page(const struct lu_env *env, struct cl_io *io,
  * \retval  -ve, 0: page wasn't added to \a queue for other reason.
  */
 static int ll_read_ahead_page(const struct lu_env *env, struct cl_io *io,
-                              struct cl_page_list *queue,
-                              int index, struct address_space *mapping)
+                             struct cl_page_list *queue,
+                             pgoff_t index, pgoff_t *max_index)
 {
+       struct cl_object *clob  = io->ci_obj;
+       struct inode     *inode = ccc_object_inode(clob);
         struct page      *vmpage;
-        struct cl_object *clob  = ll_i2info(mapping->host)->lli_clob;
         struct cl_page   *page;
         enum ra_stat      which = _NR_RA_STAT; /* keep gcc happy */
         unsigned int      gfp_mask;
@@ -519,15 +384,15 @@ static int ll_read_ahead_page(const struct lu_env *env, struct cl_io *io,
 #ifdef __GFP_NOWARN
         gfp_mask |= __GFP_NOWARN;
 #endif
-        vmpage = grab_cache_page_nowait_gfp(mapping, index, gfp_mask);
-        if (vmpage != NULL) {
-                /* Check if vmpage was truncated or reclaimed */
-                if (vmpage->mapping == mapping) {
-                        page = cl_page_find(env, clob, vmpage->index,
-                                            vmpage, CPT_CACHEABLE);
-                        if (!IS_ERR(page)) {
-                                rc = cl_read_ahead_page(env, io, queue,
-                                                        page, vmpage);
+       vmpage = grab_cache_page_nowait(inode->i_mapping, index);
+       if (vmpage != NULL) {
+               /* Check if vmpage was truncated or reclaimed */
+               if (vmpage->mapping == inode->i_mapping) {
+                       page = cl_page_find(env, clob, vmpage->index,
+                                           vmpage, CPT_CACHEABLE);
+                       if (!IS_ERR(page)) {
+                               rc = cl_read_ahead_page(env, io, queue,
+                                                       page, clob, max_index);
                                 if (rc == -ENOLCK) {
                                         which = RA_STAT_FAILED_MATCH;
                                         msg   = "lock match failed";
@@ -547,11 +412,11 @@ static int ll_read_ahead_page(const struct lu_env *env, struct cl_io *io,
                 which = RA_STAT_FAILED_GRAB_PAGE;
                 msg   = "g_c_p_n failed";
         }
-        if (msg != NULL) {
-                ll_ra_stats_inc(mapping, which);
-                CDEBUG(D_READA, "%s\n", msg);
-        }
-        RETURN(rc);
+       if (msg != NULL) {
+               ll_ra_stats_inc(inode, which);
+               CDEBUG(D_READA, "%s\n", msg);
+       }
+       RETURN(rc);
 }
 
 #define RIA_DEBUG(ria)                                                       \
@@ -559,7 +424,17 @@ static int ll_read_ahead_page(const struct lu_env *env, struct cl_io *io,
         ria->ria_start, ria->ria_end, ria->ria_stoff, ria->ria_length,\
         ria->ria_pages)
 
-#define RAS_INCREASE_STEP PTLRPC_MAX_BRW_PAGES
+/* Limit this to the blocksize instead of PTLRPC_BRW_MAX_SIZE, since we don't
+ * know what the actual RPC size is.  If this needs to change, it makes more
+ * sense to tune the i_blkbits value for the file based on the OSTs it is
+ * striped over, rather than having a constant value for all files here. */
+
+/* RAS_INCREASE_STEP should be (1UL << (inode->i_blkbits - PAGE_CACHE_SHIFT)).
+ * Temprarily set RAS_INCREASE_STEP to 1MB. After 4MB RPC is enabled
+ * by default, this should be adjusted corresponding with max_read_ahead_mb
+ * and max_read_ahead_per_file_mb otherwise the readahead budget can be used
+ * up quickly which will affect read performance siginificantly. See LU-2816 */
+#define RAS_INCREASE_STEP(inode) (ONE_MB_BRW_SIZE >> PAGE_CACHE_SHIFT)
 
 static inline int stride_io_mode(struct ll_readahead_state *ras)
 {
@@ -587,8 +462,8 @@ static unsigned long
 stride_pg_count(pgoff_t st_off, unsigned long st_len, unsigned long st_pgs,
                 unsigned long off, unsigned long length)
 {
-        unsigned long start = off > st_off ? off - st_off : 0;
-        unsigned long end = off + length > st_off ? off + length - st_off : 0;
+        __u64 start = off > st_off ? off - st_off : 0;
+        __u64 end = off + length > st_off ? off + length - st_off : 0;
         unsigned long start_left = 0;
         unsigned long end_left = 0;
         unsigned long pg_count;
@@ -606,7 +481,7 @@ stride_pg_count(pgoff_t st_off, unsigned long st_len, unsigned long st_pgs,
         if (end_left > st_pgs)
                 end_left = st_pgs;
 
-        CDEBUG(D_READA, "start %lu, end %lu start_left %lu end_left %lu \n",
+        CDEBUG(D_READA, "start "LPU64", end "LPU64" start_left %lu end_left %lu \n",
                start, end, start_left, end_left);
 
         if (start == end)
@@ -638,32 +513,34 @@ static int ras_inside_ra_window(unsigned long idx, struct ra_io_arg *ria)
          * For stride I/O mode, just check whether the idx is inside
          * the ria_pages. */
         return ria->ria_length == 0 || ria->ria_length == ria->ria_pages ||
-               (idx - ria->ria_stoff) % ria->ria_length < ria->ria_pages;
+               (idx >= ria->ria_stoff && (idx - ria->ria_stoff) %
+                ria->ria_length < ria->ria_pages);
 }
 
 static int ll_read_ahead_pages(const struct lu_env *env,
                                struct cl_io *io, struct cl_page_list *queue,
                                struct ra_io_arg *ria,
                                unsigned long *reserved_pages,
-                               struct address_space *mapping,
                                unsigned long *ra_end)
 {
-        int rc, count = 0, stride_ria;
-        unsigned long page_idx;
-
-        LASSERT(ria != NULL);
-        RIA_DEBUG(ria);
-
-        stride_ria = ria->ria_length > ria->ria_pages && ria->ria_pages > 0;
-        for (page_idx = ria->ria_start; page_idx <= ria->ria_end &&
-                        *reserved_pages > 0; page_idx++) {
-                if (ras_inside_ra_window(page_idx, ria)) {
-                        /* If the page is inside the read-ahead window*/
-                        rc = ll_read_ahead_page(env, io, queue,
-                                                page_idx, mapping);
+       int rc, count = 0;
+       bool stride_ria;
+       pgoff_t page_idx;
+       pgoff_t max_index = 0;
+
+       LASSERT(ria != NULL);
+       RIA_DEBUG(ria);
+
+       stride_ria = ria->ria_length > ria->ria_pages && ria->ria_pages > 0;
+       for (page_idx = ria->ria_start;
+            page_idx <= ria->ria_end && *reserved_pages > 0; page_idx++) {
+               if (ras_inside_ra_window(page_idx, ria)) {
+                       /* If the page is inside the read-ahead window*/
+                       rc = ll_read_ahead_page(env, io, queue,
+                                               page_idx, &max_index);
                         if (rc == 1) {
                                 (*reserved_pages)--;
-                                count ++;
+                                count++;
                         } else if (rc == -ENOLCK)
                                 break;
                 } else if (stride_ria) {
@@ -693,42 +570,40 @@ static int ll_read_ahead_pages(const struct lu_env *env,
 }
 
 int ll_readahead(const struct lu_env *env, struct cl_io *io,
-                 struct ll_readahead_state *ras, struct address_space *mapping,
-                 struct cl_page_list *queue, int flags)
+                struct cl_page_list *queue, struct ll_readahead_state *ras,
+                bool hit)
 {
-        struct vvp_io *vio = vvp_env_io(env);
-        struct vvp_thread_info *vti = vvp_env_info(env);
-        struct cl_attr *attr = ccc_env_thread_attr(env);
-        unsigned long start = 0, end = 0, reserved;
-        unsigned long ra_end, len;
-        struct inode *inode;
-        struct ll_ra_read *bead;
-        struct ra_io_arg *ria = &vti->vti_ria;
-        struct ll_inode_info *lli;
-        struct cl_object *clob;
-        int ret = 0;
-        __u64 kms;
-        ENTRY;
-
-        inode = mapping->host;
-        lli = ll_i2info(inode);
-        clob = lli->lli_clob;
-
-        memset(ria, 0, sizeof *ria);
-
-        cl_object_attr_lock(clob);
-        ret = cl_object_attr_get(env, clob, attr);
-        cl_object_attr_unlock(clob);
-
-        if (ret != 0)
-                RETURN(ret);
-        kms = attr->cat_kms;
-        if (kms == 0) {
-                ll_ra_stats_inc(mapping, RA_STAT_ZERO_LEN);
-                RETURN(0);
-        }
-
-        cfs_spin_lock(&ras->ras_lock);
+       struct vvp_io *vio = vvp_env_io(env);
+       struct vvp_thread_info *vti = vvp_env_info(env);
+       struct cl_attr *attr = ccc_env_thread_attr(env);
+       unsigned long start = 0, end = 0, reserved;
+       unsigned long ra_end, len, mlen = 0;
+       struct inode *inode;
+       struct ll_ra_read *bead;
+       struct ra_io_arg *ria = &vti->vti_ria;
+       struct cl_object *clob;
+       int ret = 0;
+       __u64 kms;
+       ENTRY;
+
+       clob = io->ci_obj;
+       inode = ccc_object_inode(clob);
+
+       memset(ria, 0, sizeof *ria);
+
+       cl_object_attr_lock(clob);
+       ret = cl_object_attr_get(env, clob, attr);
+       cl_object_attr_unlock(clob);
+
+       if (ret != 0)
+               RETURN(ret);
+       kms = attr->cat_kms;
+       if (kms == 0) {
+               ll_ra_stats_inc(inode, RA_STAT_ZERO_LEN);
+               RETURN(0);
+       }
+
+       spin_lock(&ras->ras_lock);
         if (vio->cui_ra_window_set)
                 bead = &vio->cui_bead;
         else
@@ -746,14 +621,27 @@ int ll_readahead(const struct lu_env *env, struct cl_io *io,
                 end = ras->ras_window_start + ras->ras_window_len - 1;
         }
         if (end != 0) {
-                unsigned long tmp_end;
-                /* Align RA window to optimal RPC boundary */
-                tmp_end = ((end + 1) & (~(PTLRPC_MAX_BRW_PAGES - 1))) - 1;
-                if (tmp_end > start)
-                        end = tmp_end;
+                unsigned long rpc_boundary;
+                /*
+                 * Align RA window to an optimal boundary.
+                 *
+                 * XXX This would be better to align to cl_max_pages_per_rpc
+                 * instead of PTLRPC_MAX_BRW_PAGES, because the RPC size may
+                 * be aligned to the RAID stripe size in the future and that
+                 * is more important than the RPC size.
+                 */
+                /* Note: we only trim the RPC, instead of extending the RPC
+                 * to the boundary, so to avoid reading too much pages during
+                 * random reading. */
+                rpc_boundary = ((end + 1) & (~(PTLRPC_MAX_BRW_PAGES - 1)));
+                if (rpc_boundary > 0)
+                        rpc_boundary--;
+
+                if (rpc_boundary  > start)
+                        end = rpc_boundary;
 
                 /* Truncate RA window to end of file */
-                end = min(end, (unsigned long)((kms - 1) >> CFS_PAGE_SHIFT));
+               end = min(end, (unsigned long)((kms - 1) >> PAGE_CACHE_SHIFT));
 
                 ras->ras_next_readahead = max(end, end + 1);
                 RAS_CDEBUG(ras);
@@ -766,71 +654,93 @@ int ll_readahead(const struct lu_env *env, struct cl_io *io,
                 ria->ria_length = ras->ras_stride_length;
                 ria->ria_pages = ras->ras_stride_pages;
         }
-        cfs_spin_unlock(&ras->ras_lock);
-
-        if (end == 0) {
-                ll_ra_stats_inc(mapping, RA_STAT_ZERO_WINDOW);
-                RETURN(0);
-        }
-        len = ria_page_count(ria);
-        if (len == 0)
-                RETURN(0);
-
-        reserved = ll_ra_count_get(ll_i2sbi(inode), len);
-
-        if (reserved < len)
-                ll_ra_stats_inc(mapping, RA_STAT_MAX_IN_FLIGHT);
-
-        CDEBUG(D_READA, "reserved page %lu \n", reserved);
-
-        ret = ll_read_ahead_pages(env, io, queue,
-                                  ria, &reserved, mapping, &ra_end);
-
-        LASSERTF(reserved >= 0, "reserved %lu\n", reserved);
-        if (reserved != 0)
-                ll_ra_count_put(ll_i2sbi(inode), reserved);
-
-        if (ra_end == end + 1 && ra_end == (kms >> CFS_PAGE_SHIFT))
-                ll_ra_stats_inc(mapping, RA_STAT_EOF);
-
-        /* if we didn't get to the end of the region we reserved from
-         * the ras we need to go back and update the ras so that the
-         * next read-ahead tries from where we left off.  we only do so
-         * if the region we failed to issue read-ahead on is still ahead
-         * of the app and behind the next index to start read-ahead from */
-        CDEBUG(D_READA, "ra_end %lu end %lu stride end %lu \n",
-               ra_end, end, ria->ria_end);
-
-        if (ra_end != end + 1) {
-                cfs_spin_lock(&ras->ras_lock);
-                if (ra_end < ras->ras_next_readahead &&
-                    index_in_window(ra_end, ras->ras_window_start, 0,
-                                    ras->ras_window_len)) {
-                        ras->ras_next_readahead = ra_end;
-                               RAS_CDEBUG(ras);
-                }
-                cfs_spin_unlock(&ras->ras_lock);
-        }
-
-        RETURN(ret);
+       spin_unlock(&ras->ras_lock);
+
+       if (end == 0) {
+               ll_ra_stats_inc(inode, RA_STAT_ZERO_WINDOW);
+               RETURN(0);
+       }
+       len = ria_page_count(ria);
+       if (len == 0) {
+               ll_ra_stats_inc(inode, RA_STAT_ZERO_WINDOW);
+               RETURN(0);
+       }
+
+       CDEBUG(D_READA, DFID": ria: %lu/%lu, bead: %lu/%lu, hit: %d\n",
+              PFID(lu_object_fid(&clob->co_lu)),
+              ria->ria_start, ria->ria_end,
+              bead == NULL ? 0 : bead->lrr_start,
+              bead == NULL ? 0 : bead->lrr_count,
+              hit);
+
+       /* at least to extend the readahead window to cover current read */
+       if (!hit && bead != NULL &&
+           bead->lrr_start + bead->lrr_count > ria->ria_start) {
+               /* to the end of current read window. */
+               mlen = bead->lrr_start + bead->lrr_count - ria->ria_start;
+               /* trim to RPC boundary */
+               start = ria->ria_start & (PTLRPC_MAX_BRW_PAGES - 1);
+               mlen = min(mlen, PTLRPC_MAX_BRW_PAGES - start);
+       }
+
+       reserved = ll_ra_count_get(ll_i2sbi(inode), ria, len, mlen);
+       if (reserved < len)
+               ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
+
+       CDEBUG(D_READA, "reserved pages: %lu/%lu/%lu, ra_cur %d, ra_max %lu\n",
+              reserved, len, mlen,
+              atomic_read(&ll_i2sbi(inode)->ll_ra_info.ra_cur_pages),
+              ll_i2sbi(inode)->ll_ra_info.ra_max_pages);
+
+       ret = ll_read_ahead_pages(env, io, queue, ria, &reserved, &ra_end);
+
+       if (reserved != 0)
+               ll_ra_count_put(ll_i2sbi(inode), reserved);
+
+       if (ra_end == end + 1 && ra_end == (kms >> PAGE_CACHE_SHIFT))
+               ll_ra_stats_inc(inode, RA_STAT_EOF);
+
+       /* if we didn't get to the end of the region we reserved from
+        * the ras we need to go back and update the ras so that the
+        * next read-ahead tries from where we left off.  we only do so
+        * if the region we failed to issue read-ahead on is still ahead
+        * of the app and behind the next index to start read-ahead from */
+       CDEBUG(D_READA, "ra_end %lu end %lu stride end %lu \n",
+              ra_end, end, ria->ria_end);
+
+       if (ra_end != end + 1) {
+               ll_ra_stats_inc(inode, RA_STAT_FAILED_REACH_END);
+               spin_lock(&ras->ras_lock);
+               if (ra_end < ras->ras_next_readahead &&
+                   index_in_window(ra_end, ras->ras_window_start, 0,
+                                   ras->ras_window_len)) {
+                       ras->ras_next_readahead = ra_end;
+                       RAS_CDEBUG(ras);
+               }
+               spin_unlock(&ras->ras_lock);
+       }
+
+       RETURN(ret);
 }
 
-static void ras_set_start(struct ll_readahead_state *ras, unsigned long index)
+static void ras_set_start(struct inode *inode, struct ll_readahead_state *ras,
+                         unsigned long index)
 {
-        ras->ras_window_start = index & (~(RAS_INCREASE_STEP - 1));
+       ras->ras_window_start = index & (~(RAS_INCREASE_STEP(inode) - 1));
 }
 
 /* called with the ras_lock held or from places where it doesn't matter */
-static void ras_reset(struct ll_readahead_state *ras, unsigned long index)
+static void ras_reset(struct inode *inode, struct ll_readahead_state *ras,
+                     unsigned long index)
 {
-        ras->ras_last_readpage = index;
-        ras->ras_consecutive_requests = 0;
-        ras->ras_consecutive_pages = 0;
-        ras->ras_window_len = 0;
-        ras_set_start(ras, index);
-        ras->ras_next_readahead = max(ras->ras_window_start, index);
-
-        RAS_CDEBUG(ras);
+       ras->ras_last_readpage = index;
+       ras->ras_consecutive_requests = 0;
+       ras->ras_consecutive_pages = 0;
+       ras->ras_window_len = 0;
+       ras_set_start(inode, ras, index);
+       ras->ras_next_readahead = max(ras->ras_window_start, index);
+
+       RAS_CDEBUG(ras);
 }
 
 /* called with the ras_lock held or from places where it doesn't matter */
@@ -844,33 +754,34 @@ static void ras_stride_reset(struct ll_readahead_state *ras)
 
 void ll_readahead_init(struct inode *inode, struct ll_readahead_state *ras)
 {
-        cfs_spin_lock_init(&ras->ras_lock);
-        ras_reset(ras, 0);
-        ras->ras_requests = 0;
-        CFS_INIT_LIST_HEAD(&ras->ras_read_beads);
+       spin_lock_init(&ras->ras_lock);
+       ras_reset(inode, ras, 0);
+       ras->ras_requests = 0;
+       INIT_LIST_HEAD(&ras->ras_read_beads);
 }
 
 /*
  * Check whether the read request is in the stride window.
  * If it is in the stride window, return 1, otherwise return 0.
  */
-static int index_in_stride_window(unsigned long index,
-                                  struct ll_readahead_state *ras,
-                                  struct inode *inode)
+static int index_in_stride_window(struct ll_readahead_state *ras,
+                                 unsigned long index)
 {
-        unsigned long stride_gap = index - ras->ras_last_readpage - 1;
+       unsigned long stride_gap;
+
+       if (ras->ras_stride_length == 0 || ras->ras_stride_pages == 0 ||
+           ras->ras_stride_pages == ras->ras_stride_length)
+               return 0;
 
-        if (ras->ras_stride_length == 0 || ras->ras_stride_pages == 0 ||
-            ras->ras_stride_pages == ras->ras_stride_length)
-                return 0;
+       stride_gap = index - ras->ras_last_readpage - 1;
 
-        /* If it is contiguous read */
-        if (stride_gap == 0)
-                return ras->ras_consecutive_pages + 1 <= ras->ras_stride_pages;
+       /* If it is contiguous read */
+       if (stride_gap == 0)
+               return ras->ras_consecutive_pages + 1 <= ras->ras_stride_pages;
 
-        /*Otherwise check the stride by itself */
-        return (ras->ras_stride_length - ras->ras_stride_pages) == stride_gap &&
-             ras->ras_consecutive_pages == ras->ras_stride_pages;
+       /* Otherwise check the stride by itself */
+       return (ras->ras_stride_length - ras->ras_stride_pages) == stride_gap &&
+               ras->ras_consecutive_pages == ras->ras_stride_pages;
 }
 
 static void ras_update_stride_detector(struct ll_readahead_state *ras,
@@ -946,31 +857,31 @@ static void ras_stride_increase_window(struct ll_readahead_state *ras,
         RAS_CDEBUG(ras);
 }
 
-static void ras_increase_window(struct ll_readahead_state *ras,
-                                struct ll_ra_info *ra, struct inode *inode)
+static void ras_increase_window(struct inode *inode,
+                               struct ll_readahead_state *ras,
+                               struct ll_ra_info *ra)
 {
-        /* The stretch of ra-window should be aligned with max rpc_size
-         * but current clio architecture does not support retrieve such
-         * information from lower layer. FIXME later
-         */
-        if (stride_io_mode(ras))
-                ras_stride_increase_window(ras, ra, RAS_INCREASE_STEP);
-        else
-                ras->ras_window_len = min(ras->ras_window_len +
-                                          RAS_INCREASE_STEP,
-                                          ra->ra_max_pages_per_file);
+       /* The stretch of ra-window should be aligned with max rpc_size
+        * but current clio architecture does not support retrieve such
+        * information from lower layer. FIXME later
+        */
+       if (stride_io_mode(ras))
+               ras_stride_increase_window(ras, ra, RAS_INCREASE_STEP(inode));
+       else
+               ras->ras_window_len = min(ras->ras_window_len +
+                                         RAS_INCREASE_STEP(inode),
+                                         ra->ra_max_pages_per_file);
 }
 
 void ras_update(struct ll_sb_info *sbi, struct inode *inode,
-                struct ll_readahead_state *ras, unsigned long index,
-                unsigned hit)
+               struct ll_readahead_state *ras, unsigned long index,
+               unsigned hit)
 {
-        struct ll_ra_info *ra = &sbi->ll_ra_info;
-        int zero = 0, stride_detect = 0, ra_miss = 0;
-        ENTRY;
+       struct ll_ra_info *ra = &sbi->ll_ra_info;
+       int zero = 0, stride_detect = 0, ra_miss = 0;
+       ENTRY;
 
-        cfs_spin_lock(&sbi->ll_lock);
-        cfs_spin_lock(&ras->ras_lock);
+       spin_lock(&ras->ras_lock);
 
         ll_ra_stats_inc_sbi(sbi, hit ? RA_STAT_HIT : RA_STAT_MISS);
 
@@ -999,8 +910,8 @@ void ras_update(struct ll_sb_info *sbi, struct inode *inode,
         if (ras->ras_requests == 2 && !ras->ras_request_index) {
                 __u64 kms_pages;
 
-                kms_pages = (i_size_read(inode) + CFS_PAGE_SIZE - 1) >>
-                            CFS_PAGE_SHIFT;
+               kms_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+                           PAGE_CACHE_SHIFT;
 
                 CDEBUG(D_READA, "kmsp "LPU64" mwp %lu mp %lu\n", kms_pages,
                        ra->ra_max_read_ahead_whole_pages, ra->ra_max_pages_per_file);
@@ -1015,177 +926,250 @@ void ras_update(struct ll_sb_info *sbi, struct inode *inode,
                         GOTO(out_unlock, 0);
                 }
         }
-        if (zero) {
-                /* check whether it is in stride I/O mode*/
-                if (!index_in_stride_window(index, ras, inode)) {
-                        if (ras->ras_consecutive_stride_requests == 0 &&
-                            ras->ras_request_index == 0) {
-                                ras_update_stride_detector(ras, index);
-                                ras->ras_consecutive_stride_requests ++;
-                        } else {
-                                ras_stride_reset(ras);
-                        }
-                        ras_reset(ras, index);
-                        ras->ras_consecutive_pages++;
-                        GOTO(out_unlock, 0);
-                } else {
-                        ras->ras_consecutive_pages = 0;
-                        ras->ras_consecutive_requests = 0;
-                        if (++ras->ras_consecutive_stride_requests > 1)
-                                stride_detect = 1;
-                        RAS_CDEBUG(ras);
-                }
-        } else {
-                if (ra_miss) {
-                        if (index_in_stride_window(index, ras, inode) &&
-                            stride_io_mode(ras)) {
-                                /*If stride-RA hit cache miss, the stride dector
-                                 *will not be reset to avoid the overhead of
-                                 *redetecting read-ahead mode */
-                                if (index != ras->ras_last_readpage + 1)
-                                       ras->ras_consecutive_pages = 0;
-                                ras_reset(ras, index);
-                                RAS_CDEBUG(ras);
-                        } else {
-                                /* Reset both stride window and normal RA
-                                 * window */
-                                ras_reset(ras, index);
-                                ras->ras_consecutive_pages++;
-                                ras_stride_reset(ras);
-                                GOTO(out_unlock, 0);
-                        }
-                } else if (stride_io_mode(ras)) {
-                        /* If this is contiguous read but in stride I/O mode
-                         * currently, check whether stride step still is valid,
-                         * if invalid, it will reset the stride ra window*/
-                        if (!index_in_stride_window(index, ras, inode)) {
-                                /* Shrink stride read-ahead window to be zero */
-                                ras_stride_reset(ras);
-                                ras->ras_window_len = 0;
-                                ras->ras_next_readahead = index;
-                        }
-                }
-        }
-        ras->ras_consecutive_pages++;
-        ras->ras_last_readpage = index;
-        ras_set_start(ras, index);
-
-        if (stride_io_mode(ras))
-                /* Since stride readahead is sentivite to the offset
-                 * of read-ahead, so we use original offset here,
-                 * instead of ras_window_start, which is 1M aligned*/
-                ras->ras_next_readahead = max(index,
-                                              ras->ras_next_readahead);
-        else
-                ras->ras_next_readahead = max(ras->ras_window_start,
-                                              ras->ras_next_readahead);
-        RAS_CDEBUG(ras);
-
-        /* Trigger RA in the mmap case where ras_consecutive_requests
-         * is not incremented and thus can't be used to trigger RA */
-        if (!ras->ras_window_len && ras->ras_consecutive_pages == 4) {
-                ras->ras_window_len = RAS_INCREASE_STEP;
-                GOTO(out_unlock, 0);
-        }
-
-        /* Initially reset the stride window offset to next_readahead*/
-        if (ras->ras_consecutive_stride_requests == 2 && stride_detect) {
-                /**
-                 * Once stride IO mode is detected, next_readahead should be
-                 * reset to make sure next_readahead > stride offset
-                 */
-                ras->ras_next_readahead = max(index, ras->ras_next_readahead);
-                ras->ras_stride_offset = index;
-                ras->ras_window_len = RAS_INCREASE_STEP;
-        }
-
-        /* The initial ras_window_len is set to the request size.  To avoid
-         * uselessly reading and discarding pages for random IO the window is
-         * only increased once per consecutive request received. */
-        if ((ras->ras_consecutive_requests > 1 || stride_detect) &&
-            !ras->ras_request_index)
-                ras_increase_window(ras, ra, inode);
-        EXIT;
+       if (zero) {
+               /* check whether it is in stride I/O mode*/
+               if (!index_in_stride_window(ras, index)) {
+                       if (ras->ras_consecutive_stride_requests == 0 &&
+                           ras->ras_request_index == 0) {
+                               ras_update_stride_detector(ras, index);
+                               ras->ras_consecutive_stride_requests++;
+                       } else {
+                               ras_stride_reset(ras);
+                       }
+                       ras_reset(inode, ras, index);
+                       ras->ras_consecutive_pages++;
+                       GOTO(out_unlock, 0);
+               } else {
+                       ras->ras_consecutive_pages = 0;
+                       ras->ras_consecutive_requests = 0;
+                       if (++ras->ras_consecutive_stride_requests > 1)
+                               stride_detect = 1;
+                       RAS_CDEBUG(ras);
+               }
+       } else {
+               if (ra_miss) {
+                       if (index_in_stride_window(ras, index) &&
+                           stride_io_mode(ras)) {
+                               /*If stride-RA hit cache miss, the stride dector
+                                *will not be reset to avoid the overhead of
+                                *redetecting read-ahead mode */
+                               if (index != ras->ras_last_readpage + 1)
+                                       ras->ras_consecutive_pages = 0;
+                               ras_reset(inode, ras, index);
+                               RAS_CDEBUG(ras);
+                       } else {
+                               /* Reset both stride window and normal RA
+                                * window */
+                               ras_reset(inode, ras, index);
+                               ras->ras_consecutive_pages++;
+                               ras_stride_reset(ras);
+                               GOTO(out_unlock, 0);
+                       }
+               } else if (stride_io_mode(ras)) {
+                       /* If this is contiguous read but in stride I/O mode
+                        * currently, check whether stride step still is valid,
+                        * if invalid, it will reset the stride ra window*/
+                       if (!index_in_stride_window(ras, index)) {
+                               /* Shrink stride read-ahead window to be zero */
+                               ras_stride_reset(ras);
+                               ras->ras_window_len = 0;
+                               ras->ras_next_readahead = index;
+                       }
+               }
+       }
+       ras->ras_consecutive_pages++;
+       ras->ras_last_readpage = index;
+       ras_set_start(inode, ras, index);
+
+       if (stride_io_mode(ras)) {
+               /* Since stride readahead is sentivite to the offset
+                * of read-ahead, so we use original offset here,
+                * instead of ras_window_start, which is RPC aligned */
+               ras->ras_next_readahead = max(index, ras->ras_next_readahead);
+       } else {
+               if (ras->ras_next_readahead < ras->ras_window_start)
+                       ras->ras_next_readahead = ras->ras_window_start;
+               if (!hit)
+                       ras->ras_next_readahead = index + 1;
+       }
+       RAS_CDEBUG(ras);
+
+       /* Trigger RA in the mmap case where ras_consecutive_requests
+        * is not incremented and thus can't be used to trigger RA */
+       if (!ras->ras_window_len && ras->ras_consecutive_pages == 4) {
+               ras->ras_window_len = RAS_INCREASE_STEP(inode);
+               GOTO(out_unlock, 0);
+       }
+
+       /* Initially reset the stride window offset to next_readahead*/
+       if (ras->ras_consecutive_stride_requests == 2 && stride_detect) {
+               /**
+                * Once stride IO mode is detected, next_readahead should be
+                * reset to make sure next_readahead > stride offset
+                */
+               ras->ras_next_readahead = max(index, ras->ras_next_readahead);
+               ras->ras_stride_offset = index;
+               ras->ras_window_len = RAS_INCREASE_STEP(inode);
+       }
+
+       /* The initial ras_window_len is set to the request size.  To avoid
+        * uselessly reading and discarding pages for random IO the window is
+        * only increased once per consecutive request received. */
+       if ((ras->ras_consecutive_requests > 1 || stride_detect) &&
+           !ras->ras_request_index)
+               ras_increase_window(inode, ras, ra);
+       EXIT;
 out_unlock:
-        RAS_CDEBUG(ras);
-        ras->ras_request_index++;
-        cfs_spin_unlock(&ras->ras_lock);
-        cfs_spin_unlock(&sbi->ll_lock);
-        return;
+       RAS_CDEBUG(ras);
+       ras->ras_request_index++;
+       spin_unlock(&ras->ras_lock);
+       return;
 }
 
-int ll_writepage(struct page *vmpage, struct writeback_control *unused)
+int ll_writepage(struct page *vmpage, struct writeback_control *wbc)
 {
-        struct inode           *inode = vmpage->mapping->host;
+       struct inode           *inode = vmpage->mapping->host;
+       struct ll_inode_info   *lli   = ll_i2info(inode);
         struct lu_env          *env;
         struct cl_io           *io;
         struct cl_page         *page;
         struct cl_object       *clob;
-        struct cl_2queue       *queue;
         struct cl_env_nest      nest;
+       bool redirtied = false;
+       bool unlocked = false;
         int result;
         ENTRY;
 
         LASSERT(PageLocked(vmpage));
         LASSERT(!PageWriteback(vmpage));
 
-        if (ll_i2dtexp(inode) == NULL)
-                RETURN(-EINVAL);
+       LASSERT(ll_i2dtexp(inode) != NULL);
 
-        env = cl_env_nested_get(&nest);
-        if (IS_ERR(env))
-                RETURN(PTR_ERR(env));
+       env = cl_env_nested_get(&nest);
+       if (IS_ERR(env))
+               GOTO(out, result = PTR_ERR(env));
 
-        io    = &ccc_env_info(env)->cti_io;
-        queue = &vvp_env_info(env)->vti_queue;
         clob  = ll_i2info(inode)->lli_clob;
         LASSERT(clob != NULL);
 
+        io = ccc_env_thread_io(env);
         io->ci_obj = clob;
+       io->ci_ignore_layout = 1;
         result = cl_io_init(env, io, CIT_MISC, clob);
         if (result == 0) {
                 page = cl_page_find(env, clob, vmpage->index,
                                     vmpage, CPT_CACHEABLE);
-                if (!IS_ERR(page)) {
-                        lu_ref_add(&page->cp_reference, "writepage",
-                                   cfs_current());
-                        cl_page_assume(env, io, page);
-                        /*
-                         * Mark page dirty, because this is what
-                         * ->vio_submit()->cpo_prep_write() assumes.
-                         *
-                         * XXX better solution is to detect this from within
-                         * cl_io_submit_rw() somehow.
-                         */
-                        set_page_dirty(vmpage);
-                        cl_2queue_init_page(queue, page);
-                        result = cl_io_submit_rw(env, io, CRT_WRITE,
-                                                 queue, CRP_NORMAL);
-                        cl_page_list_disown(env, io, &queue->c2_qin);
-                        if (result != 0) {
-                                /*
-                                 * There is no need to clear PG_writeback, as
-                                 * cl_io_submit_rw() calls completion callback
-                                 * on failure.
-                                 */
-                                /*
-                                 * Re-dirty page on error so it retries write,
-                                 * but not in case when IO has actually
-                                 * occurred and completed with an error.
-                                 */
-                                if (!PageError(vmpage))
-                                        set_page_dirty(vmpage);
-                        }
-                        LASSERT(!cl_page_is_owned(page, io));
-                        lu_ref_del(&page->cp_reference,
-                                   "writepage", cfs_current());
-                        cl_page_put(env, page);
-                        cl_2queue_fini(env, queue);
-                }
+               if (!IS_ERR(page)) {
+                       lu_ref_add(&page->cp_reference, "writepage",
+                                  current);
+                       cl_page_assume(env, io, page);
+                       result = cl_page_flush(env, io, page);
+                       if (result != 0) {
+                               /*
+                                * Re-dirty page on error so it retries write,
+                                * but not in case when IO has actually
+                                * occurred and completed with an error.
+                                */
+                               if (!PageError(vmpage)) {
+                                       redirty_page_for_writepage(wbc, vmpage);
+                                       result = 0;
+                                       redirtied = true;
+                               }
+                       }
+                       cl_page_disown(env, io, page);
+                       unlocked = true;
+                       lu_ref_del(&page->cp_reference,
+                                  "writepage", current);
+                       cl_page_put(env, page);
+               } else {
+                       result = PTR_ERR(page);
+               }
         }
         cl_io_fini(env, io);
+
+       if (redirtied && wbc->sync_mode == WB_SYNC_ALL) {
+               loff_t offset = cl_offset(clob, vmpage->index);
+
+               /* Flush page failed because the extent is being written out.
+                * Wait for the write of extent to be finished to avoid
+                * breaking kernel which assumes ->writepage should mark
+                * PageWriteback or clean the page. */
+               result = cl_sync_file_range(inode, offset,
+                                           offset + PAGE_CACHE_SIZE - 1,
+                                           CL_FSYNC_LOCAL, 1);
+               if (result > 0) {
+                       /* actually we may have written more than one page.
+                        * decreasing this page because the caller will count
+                        * it. */
+                       wbc->nr_to_write -= result - 1;
+                       result = 0;
+               }
+       }
+
         cl_env_nested_put(&nest, env);
-        RETURN(result);
+       GOTO(out, result);
+
+out:
+       if (result < 0) {
+               if (!lli->lli_async_rc)
+                       lli->lli_async_rc = result;
+               SetPageError(vmpage);
+               if (!unlocked)
+                       unlock_page(vmpage);
+       }
+       return result;
+}
+
+int ll_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+       struct inode *inode = mapping->host;
+       struct ll_sb_info *sbi = ll_i2sbi(inode);
+       loff_t start;
+       loff_t end;
+       enum cl_fsync_mode mode;
+       int range_whole = 0;
+       int result;
+       int ignore_layout = 0;
+       ENTRY;
+
+       if (wbc->range_cyclic) {
+               start = mapping->writeback_index << PAGE_CACHE_SHIFT;
+               end = OBD_OBJECT_EOF;
+       } else {
+               start = wbc->range_start;
+               end = wbc->range_end;
+               if (end == LLONG_MAX) {
+                       end = OBD_OBJECT_EOF;
+                       range_whole = start == 0;
+               }
+       }
+
+       mode = CL_FSYNC_NONE;
+       if (wbc->sync_mode == WB_SYNC_ALL)
+               mode = CL_FSYNC_LOCAL;
+
+       if (sbi->ll_umounting)
+               /* if the mountpoint is being umounted, all pages have to be
+                * evicted to avoid hitting LBUG when truncate_inode_pages()
+                * is called later on. */
+               ignore_layout = 1;
+
+       if (cl_i2info(inode)->lli_clob == NULL)
+               RETURN(0);
+
+       result = cl_sync_file_range(inode, start, end, mode, ignore_layout);
+       if (result > 0) {
+               wbc->nr_to_write -= result;
+               result = 0;
+        }
+
+       if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) {
+               if (end == OBD_OBJECT_EOF)
+                       mapping->writeback_index = 0;
+               else
+                       mapping->writeback_index = (end >> PAGE_CACHE_SHIFT) +1;
+       }
+       RETURN(result);
 }
 
 int ll_readpage(struct file *file, struct page *vmpage)
@@ -1194,7 +1178,7 @@ int ll_readpage(struct file *file, struct page *vmpage)
         int result;
         ENTRY;
 
-        lcc = ll_cl_init(file, vmpage, 0);
+        lcc = ll_cl_init(file, vmpage);
         if (!IS_ERR(lcc)) {
                 struct lu_env  *env  = lcc->lcc_env;
                 struct cl_io   *io   = lcc->lcc_io;
@@ -1206,14 +1190,38 @@ int ll_readpage(struct file *file, struct page *vmpage)
                         result = cl_io_read_page(env, io, page);
                 } else {
                         /* Page from a non-object file. */
-                        LASSERT(!ll_i2info(vmpage->mapping->host)->lli_smd);
                         unlock_page(vmpage);
                         result = 0;
                 }
                 ll_cl_fini(lcc);
         } else {
+                unlock_page(vmpage);
                 result = PTR_ERR(lcc);
         }
         RETURN(result);
 }
 
+int ll_page_sync_io(const struct lu_env *env, struct cl_io *io,
+                   struct cl_page *page, enum cl_req_type crt)
+{
+       struct cl_2queue  *queue;
+       int result;
+
+       LASSERT(io->ci_type == CIT_READ || io->ci_type == CIT_WRITE);
+
+       queue = &io->ci_queue;
+       cl_2queue_init_page(queue, page);
+
+       result = cl_io_submit_sync(env, io, crt, queue, 0);
+       LASSERT(cl_page_is_owned(page, io));
+
+       if (crt == CRT_READ)
+               /*
+                * in CRT_WRITE case page is left locked even in case of
+                * error.
+                */
+               cl_page_list_disown(env, io, &queue->c2_qin);
+       cl_2queue_fini(env, queue);
+
+       return result;
+}