LU-3259 clio: Revise read ahead implementation

[fs/lustre-release.git] / lustre / lov / lov_io.c

diff --git a/lustre/lov/lov_io.c b/lustre/lov/lov_io.c
index 8448721..a24a984 100644 (file)
--- a/lustre/lov/lov_io.c
+++ b/lustre/lov/lov_io.c
@@ -578,6 +578,65 @@ static void lov_io_unlock(const struct lu_env *env,
         EXIT;
 }
 
+static int lov_io_read_ahead(const struct lu_env *env,
+                            const struct cl_io_slice *ios,
+                            pgoff_t start, struct cl_read_ahead *ra)
+{
+       struct lov_io           *lio = cl2lov_io(env, ios);
+       struct lov_object       *loo = lio->lis_object;
+       struct cl_object        *obj = lov2cl(loo);
+       struct lov_layout_raid0 *r0 = lov_r0(loo);
+       struct lov_io_sub       *sub;
+       obd_off                  suboff;
+       pgoff_t                  ra_end;
+       unsigned int             pps; /* pages per stripe */
+       int                      stripe;
+       int                      rc;
+       ENTRY;
+
+       stripe = lov_stripe_number(loo->lo_lsm, cl_offset(obj, start));
+       if (unlikely(r0->lo_sub[stripe] == NULL))
+               RETURN(-EIO);
+
+       sub = lov_sub_get(env, lio, stripe);
+
+       lov_stripe_offset(loo->lo_lsm, cl_offset(obj, start), stripe, &suboff);
+       rc = cl_io_read_ahead(sub->sub_env, sub->sub_io,
+                             cl_index(lovsub2cl(r0->lo_sub[stripe]), suboff),
+                             ra);
+       lov_sub_put(sub);
+
+       CDEBUG(D_READA, DFID " cra_end = %lu, stripes = %d, rc = %d\n",
+              PFID(lu_object_fid(lov2lu(loo))), ra->cra_end, r0->lo_nr, rc);
+       if (rc != 0)
+               RETURN(rc);
+
+       /**
+        * Adjust the stripe index by layout of raid0. ra->cra_end is the maximum
+        * page index covered by an underlying DLM lock.
+        * This function converts cra_end from stripe level to file level, and
+        * make sure it's not beyond stripe boundary.
+        */
+       if (r0->lo_nr == 1) /* single stripe file */
+               RETURN(0);
+
+       /* cra_end is stripe level, convert it into file level */
+       ra_end = ra->cra_end;
+       if (ra_end != CL_PAGE_EOF)
+               ra_end = lov_stripe_pgoff(loo->lo_lsm, ra_end, stripe);
+
+       pps = loo->lo_lsm->lsm_stripe_size >> PAGE_CACHE_SHIFT;
+
+       CDEBUG(D_READA, DFID " max_index = %lu, pps = %u, "
+              "stripe_size = %u, stripe no = %u, start index = %lu\n",
+              PFID(lu_object_fid(lov2lu(loo))), ra_end, pps,
+              loo->lo_lsm->lsm_stripe_size, stripe, start);
+
+       /* never exceed the end of the stripe */
+       ra->cra_end = min_t(pgoff_t, ra_end, start + pps - start % pps - 1);
+       RETURN(0);
+}
+
 /**
  * lov implementation of cl_operations::cio_submit() method. It takes a list
  * of pages in \a queue, splits it into per-stripe sub-lists, invokes
@@ -826,6 +885,7 @@ static const struct cl_io_operations lov_io_ops = {
                        .cio_fini      = lov_io_fini
                }
        },
+       .cio_read_ahead                = lov_io_read_ahead,
        .cio_submit                    = lov_io_submit,
        .cio_commit_async              = lov_io_commit_async,
 };