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LU-12043 llite: make sure readahead cover current read
[fs/lustre-release.git] / lustre / llite / rw.c
index f41f559..d8f4075 100644 (file)
  *
  * You should have received a copy of the GNU General Public License
  * version 2 along with this program; If not, see
- * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * http://www.gnu.org/licenses/gpl-2.0.html
  *
  * GPL HEADER END
  */
@@ -27,7 +23,7 @@
  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2011, 2015, Intel Corporation.
+ * Copyright (c) 2011, 2017, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
 #include <asm/uaccess.h>
 
 #include <linux/fs.h>
+#include <linux/file.h>
 #include <linux/stat.h>
 #include <asm/uaccess.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 /* current_is_kswapd() */
 #include <linux/swap.h>
+#include <linux/task_io_accounting_ops.h>
 
 #define DEBUG_SUBSYSTEM S_LLITE
 
@@ -120,8 +118,8 @@ void ll_ra_count_put(struct ll_sb_info *sbi, unsigned long len)
 
 static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which)
 {
-        LASSERTF(which >= 0 && which < _NR_RA_STAT, "which: %u\n", which);
-        lprocfs_counter_incr(sbi->ll_ra_stats, which);
+       LASSERTF(which < _NR_RA_STAT, "which: %u\n", which);
+       lprocfs_counter_incr(sbi->ll_ra_stats, which);
 }
 
 void ll_ra_stats_inc(struct inode *inode, enum ra_stat which)
@@ -133,14 +131,15 @@ void ll_ra_stats_inc(struct inode *inode, enum ra_stat which)
 #define RAS_CDEBUG(ras) \
        CDEBUG(D_READA,                                                      \
               "lrp %lu cr %lu cp %lu ws %lu wl %lu nra %lu rpc %lu "        \
-              "r %lu ri %lu csr %lu sf %lu sp %lu sl %lu\n",                \
+              "r %lu ri %lu csr %lu sf %lu sp %lu sl %lu lr %lu\n", \
               ras->ras_last_readpage, ras->ras_consecutive_requests,        \
               ras->ras_consecutive_pages, ras->ras_window_start,            \
               ras->ras_window_len, ras->ras_next_readahead,                 \
               ras->ras_rpc_size,                                            \
               ras->ras_requests, ras->ras_request_index,                    \
               ras->ras_consecutive_stride_requests, ras->ras_stride_offset, \
-              ras->ras_stride_pages, ras->ras_stride_length)
+              ras->ras_stride_pages, ras->ras_stride_length,                \
+              ras->ras_async_last_readpage)
 
 static int index_in_window(unsigned long index, unsigned long point,
                            unsigned long before, unsigned long after)
@@ -231,7 +230,7 @@ out:
        if (vmpage != NULL) {
                if (rc != 0)
                        unlock_page(vmpage);
-               page_cache_release(vmpage);
+               put_page(vmpage);
        }
        if (msg != NULL) {
                ll_ra_stats_inc(inode, which);
@@ -293,7 +292,7 @@ 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 "LPU64", end "LPU64" start_left %lu end_left %lu \n",
+       CDEBUG(D_READA, "start %llu, end %llu start_left %lu end_left %lu\n",
                start, end, start_left, end_left);
 
         if (start == end)
@@ -342,12 +341,11 @@ static int ras_inside_ra_window(unsigned long idx, struct ra_io_arg *ria)
 static unsigned long
 ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
                    struct cl_page_list *queue, struct ll_readahead_state *ras,
-                   struct ra_io_arg *ria)
+                   struct ra_io_arg *ria, pgoff_t *ra_end)
 {
        struct cl_read_ahead ra = { 0 };
-       int rc = 0;
+       int rc = 0, count = 0;
        bool stride_ria;
-       unsigned long ra_end = 0;
        pgoff_t page_idx;
 
        LASSERT(ria != NULL);
@@ -373,7 +371,7 @@ ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
                                         io->ci_obj, ra.cra_end, page_idx);
                                /* update read ahead RPC size.
                                 * NB: it's racy but doesn't matter */
-                               if (ras->ras_rpc_size > ra.cra_rpc_size &&
+                               if (ras->ras_rpc_size != ra.cra_rpc_size &&
                                    ra.cra_rpc_size > 0)
                                        ras->ras_rpc_size = ra.cra_rpc_size;
                                /* trim it to align with optimal RPC size */
@@ -393,9 +391,13 @@ ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
                        if (rc < 0)
                                break;
 
-                       ra_end = page_idx;
-                       if (rc == 0)
+                       *ra_end = page_idx;
+                       /* Only subtract from reserve & count the page if we
+                        * really did readahead on that page. */
+                       if (rc == 0) {
                                ria->ria_reserved--;
+                               count++;
+                       }
                 } else if (stride_ria) {
                         /* If it is not in the read-ahead window, and it is
                          * read-ahead mode, then check whether it should skip
@@ -422,18 +424,177 @@ ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
 
        cl_read_ahead_release(env, &ra);
 
-       return ra_end;
+       return count;
+}
+
+static void ll_readahead_work_free(struct ll_readahead_work *work)
+{
+       fput(work->lrw_file);
+       OBD_FREE_PTR(work);
+}
+
+static void ll_readahead_handle_work(struct work_struct *wq);
+static void ll_readahead_work_add(struct inode *inode,
+                                 struct ll_readahead_work *work)
+{
+       INIT_WORK(&work->lrw_readahead_work, ll_readahead_handle_work);
+       queue_work(ll_i2sbi(inode)->ll_ra_info.ll_readahead_wq,
+                  &work->lrw_readahead_work);
+}
+
+static int ll_readahead_file_kms(const struct lu_env *env,
+                               struct cl_io *io, __u64 *kms)
+{
+       struct cl_object *clob;
+       struct inode *inode;
+       struct cl_attr *attr = vvp_env_thread_attr(env);
+       int ret;
+
+       clob = io->ci_obj;
+       inode = vvp_object_inode(clob);
+
+       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;
+       return 0;
+}
+
+static void ll_readahead_handle_work(struct work_struct *wq)
+{
+       struct ll_readahead_work *work;
+       struct lu_env *env;
+       __u16 refcheck;
+       struct ra_io_arg *ria;
+       struct inode *inode;
+       struct ll_file_data *fd;
+       struct ll_readahead_state *ras;
+       struct cl_io *io;
+       struct cl_2queue *queue;
+       pgoff_t ra_end = 0;
+       unsigned long len, mlen = 0;
+       struct file *file;
+       __u64 kms;
+       int rc;
+       unsigned long end_index;
+
+       work = container_of(wq, struct ll_readahead_work,
+                           lrw_readahead_work);
+       fd = LUSTRE_FPRIVATE(work->lrw_file);
+       ras = &fd->fd_ras;
+       file = work->lrw_file;
+       inode = file_inode(file);
+
+       env = cl_env_alloc(&refcheck, LCT_NOREF);
+       if (IS_ERR(env))
+               GOTO(out_free_work, rc = PTR_ERR(env));
+
+       io = vvp_env_thread_io(env);
+       ll_io_init(io, file, CIT_READ);
+
+       rc = ll_readahead_file_kms(env, io, &kms);
+       if (rc != 0)
+               GOTO(out_put_env, rc);
+
+       if (kms == 0) {
+               ll_ra_stats_inc(inode, RA_STAT_ZERO_LEN);
+               GOTO(out_put_env, rc = 0);
+       }
+
+       ria = &ll_env_info(env)->lti_ria;
+       memset(ria, 0, sizeof(*ria));
+
+       ria->ria_start = work->lrw_start;
+       /* Truncate RA window to end of file */
+       end_index = (unsigned long)((kms - 1) >> PAGE_SHIFT);
+       if (end_index <= work->lrw_end) {
+               work->lrw_end = end_index;
+               ria->ria_eof = true;
+       }
+       if (work->lrw_end <= work->lrw_start)
+               GOTO(out_put_env, rc = 0);
+
+       ria->ria_end = work->lrw_end;
+       len = ria->ria_end - ria->ria_start + 1;
+       ria->ria_reserved = ll_ra_count_get(ll_i2sbi(inode), ria,
+                                           ria_page_count(ria), mlen);
+
+       CDEBUG(D_READA,
+              "async reserved pages: %lu/%lu/%lu, ra_cur %d, ra_max %lu\n",
+              ria->ria_reserved, len, mlen,
+              atomic_read(&ll_i2sbi(inode)->ll_ra_info.ra_cur_pages),
+              ll_i2sbi(inode)->ll_ra_info.ra_max_pages);
+
+       if (ria->ria_reserved < len) {
+               ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
+               if (PAGES_TO_MiB(ria->ria_reserved) < 1) {
+                       ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
+                       GOTO(out_put_env, rc = 0);
+               }
+       }
+
+       rc = cl_io_rw_init(env, io, CIT_READ, ria->ria_start, len);
+       if (rc)
+               GOTO(out_put_env, rc);
+
+       vvp_env_io(env)->vui_io_subtype = IO_NORMAL;
+       vvp_env_io(env)->vui_fd = fd;
+       io->ci_state = CIS_LOCKED;
+       io->ci_async_readahead = true;
+       rc = cl_io_start(env, io);
+       if (rc)
+               GOTO(out_io_fini, rc);
+
+       queue = &io->ci_queue;
+       cl_2queue_init(queue);
+
+       rc = ll_read_ahead_pages(env, io, &queue->c2_qin, ras, ria, &ra_end);
+       if (ria->ria_reserved != 0)
+               ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
+       if (queue->c2_qin.pl_nr > 0) {
+               int count = queue->c2_qin.pl_nr;
+
+               rc = cl_io_submit_rw(env, io, CRT_READ, queue);
+               if (rc == 0)
+                       task_io_account_read(PAGE_SIZE * count);
+       }
+       if (ria->ria_end == ra_end && ra_end == (kms >> PAGE_SHIFT))
+               ll_ra_stats_inc(inode, RA_STAT_EOF);
+
+       if (ra_end != ria->ria_end)
+               ll_ra_stats_inc(inode, RA_STAT_FAILED_REACH_END);
+
+       /* TODO: discard all pages until page reinit route is implemented */
+       cl_page_list_discard(env, io, &queue->c2_qin);
+
+       /* Unlock unsent read pages in case of error. */
+       cl_page_list_disown(env, io, &queue->c2_qin);
+
+       cl_2queue_fini(env, queue);
+out_io_fini:
+       cl_io_end(env, io);
+       cl_io_fini(env, io);
+out_put_env:
+       cl_env_put(env, &refcheck);
+out_free_work:
+       if (ra_end > 0)
+               ll_ra_stats_inc_sbi(ll_i2sbi(inode), RA_STAT_ASYNC);
+       ll_readahead_work_free(work);
 }
 
 static int ll_readahead(const struct lu_env *env, struct cl_io *io,
                        struct cl_page_list *queue,
-                       struct ll_readahead_state *ras, bool hit)
+                       struct ll_readahead_state *ras, bool hit,
+                       struct file *file)
 {
        struct vvp_io *vio = vvp_env_io(env);
        struct ll_thread_info *lti = ll_env_info(env);
-       struct cl_attr *attr = vvp_env_thread_attr(env);
        unsigned long len, mlen = 0;
-       pgoff_t ra_end, start = 0, end = 0;
+       pgoff_t ra_end = 0, start = 0, end = 0;
        struct inode *inode;
        struct ra_io_arg *ria = &lti->lti_ria;
        struct cl_object *clob;
@@ -445,14 +606,10 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io,
        inode = vvp_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);
-
+       ret = ll_readahead_file_kms(env, io, &kms);
        if (ret != 0)
                RETURN(ret);
-       kms = attr->cat_kms;
+
        if (kms == 0) {
                ll_ra_stats_inc(inode, RA_STAT_ZERO_LEN);
                RETURN(0);
@@ -484,14 +641,11 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io,
                unsigned long end_index;
 
                /* Truncate RA window to end of file */
-               end_index = (unsigned long)((kms - 1) >> PAGE_CACHE_SHIFT);
+               end_index = (unsigned long)((kms - 1) >> PAGE_SHIFT);
                if (end_index <= end) {
                        end = end_index;
                        ria->ria_eof = true;
                }
-
-               ras->ras_next_readahead = max(end, end + 1);
-               RAS_CDEBUG(ras);
         }
         ria->ria_start = start;
         ria->ria_end = end;
@@ -513,6 +667,7 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io,
                RETURN(0);
        }
 
+       RAS_CDEBUG(ras);
        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,
@@ -522,16 +677,8 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io,
 
        /* at least to extend the readahead window to cover current read */
        if (!hit && vio->vui_ra_valid &&
-           vio->vui_ra_start + vio->vui_ra_count > ria->ria_start) {
-               unsigned long remainder;
-
-               /* to the end of current read window. */
-               mlen = vio->vui_ra_start + vio->vui_ra_count - ria->ria_start;
-               /* trim to RPC boundary */
-               ras_align(ras, ria->ria_start, &remainder);
-               mlen = min(mlen, ras->ras_rpc_size - remainder);
-               ria->ria_end_min = ria->ria_start + mlen;
-       }
+           vio->vui_ra_start + vio->vui_ra_count > ria->ria_start)
+               ria->ria_end_min = vio->vui_ra_start + vio->vui_ra_count - 1;
 
        ria->ria_reserved = ll_ra_count_get(ll_i2sbi(inode), ria, len, mlen);
        if (ria->ria_reserved < len)
@@ -542,32 +689,26 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io,
               atomic_read(&ll_i2sbi(inode)->ll_ra_info.ra_cur_pages),
               ll_i2sbi(inode)->ll_ra_info.ra_max_pages);
 
-       ra_end = ll_read_ahead_pages(env, io, queue, ras, ria);
+       ret = ll_read_ahead_pages(env, io, queue, ras, ria, &ra_end);
 
        if (ria->ria_reserved != 0)
                ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
 
-       if (ra_end == end && ra_end == (kms >> PAGE_CACHE_SHIFT))
+       if (ra_end == end && ra_end == (kms >> PAGE_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 pages = %d\n",
               ra_end, end, ria->ria_end, ret);
 
-       if (ra_end > 0 && ra_end != end) {
+       if (ra_end != end)
                ll_ra_stats_inc(inode, RA_STAT_FAILED_REACH_END);
+       if (ra_end > 0) {
+               /* update the ras so that the next read-ahead tries from
+                * where we left off. */
                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 + 1;
-                       RAS_CDEBUG(ras);
-               }
+               ras->ras_next_readahead = ra_end + 1;
                spin_unlock(&ras->ras_lock);
+               RAS_CDEBUG(ras);
        }
 
        RETURN(ret);
@@ -722,7 +863,10 @@ static void ras_increase_window(struct inode *inode,
 
                wlen = min(ras->ras_window_len + ras->ras_rpc_size,
                           ra->ra_max_pages_per_file);
-               ras->ras_window_len = ras_align(ras, wlen, NULL);
+               if (wlen < ras->ras_rpc_size)
+                       ras->ras_window_len = wlen;
+               else
+                       ras->ras_window_len = ras_align(ras, wlen, NULL);
        }
 }
 
@@ -737,6 +881,9 @@ static void ras_update(struct ll_sb_info *sbi, struct inode *inode,
 
        spin_lock(&ras->ras_lock);
 
+       if (!hit)
+               CDEBUG(D_READA, DFID " pages at %lu miss.\n",
+                      PFID(ll_inode2fid(inode)), index);
         ll_ra_stats_inc_sbi(sbi, hit ? RA_STAT_HIT : RA_STAT_MISS);
 
         /* reset the read-ahead window in two cases.  First when the app seeks
@@ -764,10 +911,10 @@ static 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) + PAGE_CACHE_SIZE - 1) >>
-                           PAGE_CACHE_SHIFT;
+               kms_pages = (i_size_read(inode) + PAGE_SIZE - 1) >>
+                           PAGE_SHIFT;
 
-                CDEBUG(D_READA, "kmsp "LPU64" mwp %lu mp %lu\n", kms_pages,
+               CDEBUG(D_READA, "kmsp %llu mwp %lu mp %lu\n", kms_pages,
                        ra->ra_max_read_ahead_whole_pages, ra->ra_max_pages_per_file);
 
                 if (kms_pages &&
@@ -803,12 +950,19 @@ static void ras_update(struct ll_sb_info *sbi, struct inode *inode,
                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);
+
+                               /* If stride-RA hit cache miss, the stride
+                                * detector will not be reset to avoid the
+                                * overhead of redetecting read-ahead mode,
+                                * but on the condition that the stride window
+                                * is still intersect with normal sequential
+                                * read-ahead window. */
+                               if (ras->ras_window_start <
+                                   ras->ras_stride_offset)
+                                       ras_stride_reset(ras);
                                RAS_CDEBUG(ras);
                        } else {
                                /* Reset both stride window and normal RA
@@ -838,7 +992,8 @@ static void ras_update(struct ll_sb_info *sbi, struct inode *inode,
                /* 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);
+               ras->ras_next_readahead = max(index + 1,
+                                             ras->ras_next_readahead);
                ras->ras_window_start = max(ras->ras_stride_offset,
                                            ras->ras_window_start);
        } else {
@@ -953,7 +1108,7 @@ int ll_writepage(struct page *vmpage, struct writeback_control *wbc)
                 * breaking kernel which assumes ->writepage should mark
                 * PageWriteback or clean the page. */
                result = cl_sync_file_range(inode, offset,
-                                           offset + PAGE_CACHE_SIZE - 1,
+                                           offset + PAGE_SIZE - 1,
                                            CL_FSYNC_LOCAL, 1);
                if (result > 0) {
                        /* actually we may have written more than one page.
@@ -981,17 +1136,15 @@ out:
 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;
+               start = mapping->writeback_index << PAGE_SHIFT;
                end = OBD_OBJECT_EOF;
        } else {
                start = wbc->range_start;
@@ -1006,16 +1159,13 @@ int ll_writepages(struct address_space *mapping, struct writeback_control *wbc)
        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 (ll_i2info(inode)->lli_clob == NULL)
                RETURN(0);
 
-       result = cl_sync_file_range(inode, start, end, mode, ignore_layout);
+       /* for directio, it would call writepages() to evict cached pages
+        * inside the IO context of write, which will cause deadlock at
+        * layout_conf since it waits for active IOs to complete. */
+       result = cl_sync_file_range(inode, start, end, mode, 1);
        if (result > 0) {
                wbc->nr_to_write -= result;
                result = 0;
@@ -1025,7 +1175,7 @@ int ll_writepages(struct address_space *mapping, struct writeback_control *wbc)
                if (end == OBD_OBJECT_EOF)
                        mapping->writeback_index = 0;
                else
-                       mapping->writeback_index = (end >> PAGE_CACHE_SHIFT) +1;
+                       mapping->writeback_index = (end >> PAGE_SHIFT) + 1;
        }
        RETURN(result);
 }
@@ -1076,7 +1226,7 @@ void ll_cl_remove(struct file *file, const struct lu_env *env)
        write_unlock(&fd->fd_lock);
 }
 
-static int ll_io_read_page(const struct lu_env *env, struct cl_io *io,
+int ll_io_read_page(const struct lu_env *env, struct cl_io *io,
                           struct cl_page *page, struct file *file)
 {
        struct inode              *inode  = vvp_object_inode(page->cp_obj);
@@ -1084,6 +1234,7 @@ static int ll_io_read_page(const struct lu_env *env, struct cl_io *io,
        struct ll_file_data       *fd     = LUSTRE_FPRIVATE(file);
        struct ll_readahead_state *ras    = &fd->fd_ras;
        struct cl_2queue          *queue  = &io->ci_queue;
+       struct cl_sync_io         *anchor = NULL;
        struct vvp_page           *vpg;
        int                        rc = 0;
        bool                       uptodate;
@@ -1111,6 +1262,10 @@ static int ll_io_read_page(const struct lu_env *env, struct cl_io *io,
                cl_page_export(env, page, 1);
                cl_page_disown(env, io, page);
        } else {
+               anchor = &vvp_env_info(env)->vti_anchor;
+               cl_sync_io_init(anchor, 1, &cl_sync_io_end);
+               page->cp_sync_io = anchor;
+
                cl_2queue_add(queue, page);
        }
 
@@ -1119,46 +1274,126 @@ static int ll_io_read_page(const struct lu_env *env, struct cl_io *io,
                int rc2;
 
                rc2 = ll_readahead(env, io, &queue->c2_qin, ras,
-                                  uptodate);
+                                  uptodate, file);
                CDEBUG(D_READA, DFID "%d pages read ahead at %lu\n",
                       PFID(ll_inode2fid(inode)), rc2, vvp_index(vpg));
        }
 
-       if (queue->c2_qin.pl_nr > 0)
+       if (queue->c2_qin.pl_nr > 0) {
+               int count = queue->c2_qin.pl_nr;
                rc = cl_io_submit_rw(env, io, CRT_READ, queue);
+               if (rc == 0)
+                       task_io_account_read(PAGE_SIZE * count);
+       }
 
-       /*
-        * Unlock unsent pages in case of error.
-        */
+
+       if (anchor != NULL && !cl_page_is_owned(page, io)) { /* have sent */
+               rc = cl_sync_io_wait(env, anchor, 0);
+
+               cl_page_assume(env, io, page);
+               cl_page_list_del(env, &queue->c2_qout, page);
+
+               if (!PageUptodate(cl_page_vmpage(page))) {
+                       /* Failed to read a mirror, discard this page so that
+                        * new page can be created with new mirror.
+                        *
+                        * TODO: this is not needed after page reinit
+                        * route is implemented */
+                       cl_page_discard(env, io, page);
+               }
+               cl_page_disown(env, io, page);
+       }
+
+       /* TODO: discard all pages until page reinit route is implemented */
+       cl_page_list_discard(env, io, &queue->c2_qin);
+
+       /* Unlock unsent read pages in case of error. */
        cl_page_list_disown(env, io, &queue->c2_qin);
+
        cl_2queue_fini(env, queue);
 
        RETURN(rc);
 }
 
+/*
+ * Possible return value:
+ * 0 no async readahead triggered and fast read could not be used.
+ * 1 no async readahead, but fast read could be used.
+ * 2 async readahead triggered and fast read could be used too.
+ * < 0 on error.
+ */
+static int kickoff_async_readahead(struct file *file, unsigned long pages)
+{
+       struct ll_readahead_work *lrw;
+       struct inode *inode = file_inode(file);
+       struct ll_sb_info *sbi = ll_i2sbi(inode);
+       struct ll_file_data *fd = LUSTRE_FPRIVATE(file);
+       struct ll_readahead_state *ras = &fd->fd_ras;
+       struct ll_ra_info *ra = &sbi->ll_ra_info;
+       unsigned long throttle;
+       unsigned long start = ras_align(ras, ras->ras_next_readahead, NULL);
+       unsigned long end = start + pages - 1;
+
+       throttle = min(ra->ra_async_pages_per_file_threshold,
+                      ra->ra_max_pages_per_file);
+       /*
+        * If this is strided i/o or the window is smaller than the
+        * throttle limit, we do not do async readahead. Otherwise,
+        * we do async readahead, allowing the user thread to do fast i/o.
+        */
+       if (stride_io_mode(ras) || !throttle ||
+           ras->ras_window_len < throttle)
+               return 0;
+
+       if ((atomic_read(&ra->ra_cur_pages) + pages) > ra->ra_max_pages)
+               return 0;
+
+       if (ras->ras_async_last_readpage == start)
+               return 1;
+
+       /* ll_readahead_work_free() free it */
+       OBD_ALLOC_PTR(lrw);
+       if (lrw) {
+               lrw->lrw_file = get_file(file);
+               lrw->lrw_start = start;
+               lrw->lrw_end = end;
+               spin_lock(&ras->ras_lock);
+               ras->ras_next_readahead = end + 1;
+               ras->ras_async_last_readpage = start;
+               spin_unlock(&ras->ras_lock);
+               ll_readahead_work_add(inode, lrw);
+       } else {
+               return -ENOMEM;
+       }
+
+       return 2;
+}
+
 int ll_readpage(struct file *file, struct page *vmpage)
 {
        struct inode *inode = file_inode(file);
        struct cl_object *clob = ll_i2info(inode)->lli_clob;
        struct ll_cl_context *lcc;
-       const struct lu_env  *env;
-       struct cl_io   *io;
+       const struct lu_env  *env = NULL;
+       struct cl_io   *io = NULL;
        struct cl_page *page;
+       struct ll_sb_info *sbi = ll_i2sbi(inode);
        int result;
        ENTRY;
 
        lcc = ll_cl_find(file);
-       if (lcc == NULL) {
-               unlock_page(vmpage);
-               RETURN(-EIO);
+       if (lcc != NULL) {
+               env = lcc->lcc_env;
+               io  = lcc->lcc_io;
        }
 
-       env = lcc->lcc_env;
-       io  = lcc->lcc_io;
        if (io == NULL) { /* fast read */
                struct inode *inode = file_inode(file);
                struct ll_file_data *fd = LUSTRE_FPRIVATE(file);
                struct ll_readahead_state *ras = &fd->fd_ras;
+               struct lu_env  *local_env = NULL;
+               unsigned long fast_read_pages =
+                       max(RA_REMAIN_WINDOW_MIN, ras->ras_rpc_size);
                struct vvp_page *vpg;
 
                result = -ENODATA;
@@ -1168,6 +1403,7 @@ int ll_readpage(struct file *file, struct page *vmpage)
                page = cl_vmpage_page(vmpage, clob);
                if (page == NULL) {
                        unlock_page(vmpage);
+                       ll_ra_stats_inc_sbi(sbi, RA_STAT_FAILED_FAST_READ);
                        RETURN(result);
                }
 
@@ -1175,14 +1411,13 @@ int ll_readpage(struct file *file, struct page *vmpage)
                if (vpg->vpg_defer_uptodate) {
                        enum ras_update_flags flags = LL_RAS_HIT;
 
-                       if (lcc->lcc_type == LCC_MMAP)
+                       if (lcc && lcc->lcc_type == LCC_MMAP)
                                flags |= LL_RAS_MMAP;
 
                        /* For fast read, it updates read ahead state only
                         * if the page is hit in cache because non cache page
                         * case will be handled by slow read later. */
-                       ras_update(ll_i2sbi(inode), inode, ras, vvp_index(vpg),
-                                  flags);
+                       ras_update(sbi, inode, ras, vvp_index(vpg), flags);
                        /* avoid duplicate ras_update() call */
                        vpg->vpg_ra_updated = 1;
 
@@ -1190,16 +1425,31 @@ int ll_readpage(struct file *file, struct page *vmpage)
                         * the case, we can't do fast IO because we will need
                         * a cl_io to issue the RPC. */
                        if (ras->ras_window_start + ras->ras_window_len <
-                           ras->ras_next_readahead + PTLRPC_MAX_BRW_PAGES) {
-                               /* export the page and skip io stack */
-                               vpg->vpg_ra_used = 1;
-                               cl_page_export(env, page, 1);
+                           ras->ras_next_readahead + fast_read_pages ||
+                           kickoff_async_readahead(file, fast_read_pages) > 0)
                                result = 0;
-                       }
                }
 
-               unlock_page(vmpage);
+               if (!env) {
+                       local_env = cl_env_percpu_get();
+                       env = local_env;
+               }
+
+               /* export the page and skip io stack */
+               if (result == 0) {
+                       vpg->vpg_ra_used = 1;
+                       cl_page_export(env, page, 1);
+               } else {
+                       ll_ra_stats_inc_sbi(sbi, RA_STAT_FAILED_FAST_READ);
+               }
+               /* release page refcount before unlocking the page to ensure
+                * the object won't be destroyed in the calling path of
+                * cl_page_put(). Please see comment in ll_releasepage(). */
                cl_page_put(env, page);
+               unlock_page(vmpage);
+               if (local_env)
+                       cl_env_percpu_put(local_env);
+
                RETURN(result);
        }
 
@@ -1209,6 +1459,7 @@ int ll_readpage(struct file *file, struct page *vmpage)
                LASSERT(page->cp_type == CPT_CACHEABLE);
                if (likely(!PageUptodate(vmpage))) {
                        cl_page_assume(env, io, page);
+
                        result = ll_io_read_page(env, io, page, file);
                } else {
                        /* Page from a non-object file. */
@@ -1222,28 +1473,3 @@ int ll_readpage(struct file *file, struct page *vmpage)
         }
        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;
-}