arbiter: write performance improvement

Backport of: http://review.gluster.org/#/c/13906

Problem: The throughput for a 'dd' workload was much less for arbiter
configuration when compared to normal replica-3 volume. There were 2
issues:

i)arbiter_writev was using the request dict as response dict while
unwinding, leading to incorect GLUSTERFS_WRITE_IS_APPEND and
GLUSTERFS_OPEN_FD_COUNT values (=4), leading to immediate post-ops
because is_afr_delayed_changelog_post_op_needed() failed due to
afr_are_multiple_fds_opened() check.

ii) The arbiter code in afr was setting local->transaction.{start and len} =0
to take full file locks. What this meant was even for simultaenous but
non-overlapping writevs, afr_transaction_eager_lock_init() was not
happening because afr_locals_overlap() always stays true. Consequently
is_afr_delayed_changelog_post_op_needed() failed due to
local->delayed_post_op not being set.

Fix:
i) Send appropriate response dict values in arbiter_writev.
ii) Modify flock params instead of local->transaction.{start and len} to
take full file locks in the transaction.

Also changed _fill_writev_xdata() in posix to fill rsp_xdata for
whatever key is requested for.

Change-Id: I1c5fc5e98aba49ade540bb441a022e65b753432a
BUG: 1324809
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Reported-by: Robert Rauch <robert.rauch@gns-systems.de>
Reported-by: Russel Purinton <russell.purinton@gmail.com>
Reviewed-on: http://review.gluster.org/13925
Smoke: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>

1 files changed, 49 insertions, 8 deletions

diff --git a/xlators/features/arbiter/src/arbiter.c b/xlators/features/arbiter/src/arbiter.c
index 87145da5680..92dcbeaf9eb 100644
--- a/xlators/features/arbiter/src/arbiter.c
+++ b/xlators/features/arbiter/src/arbiter.c
@@ -133,8 +133,7 @@ arbiter_truncate (call_frame_t *frame, xlator_t *this, loc_t *loc, off_t offset,
         }
         buf = ctx->iattbuf;
 unwind:
-        STACK_UNWIND_STRICT (truncate, frame, op_ret, op_errno, buf, buf,
-                             xdata);
+        STACK_UNWIND_STRICT (truncate, frame, op_ret, op_errno, buf, buf, NULL);
         return 0;
 }
 
@@ -157,10 +156,48 @@ arbiter_ftruncate (call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
         buf = ctx->iattbuf;
 unwind:
         STACK_UNWIND_STRICT (ftruncate, frame, op_ret, op_errno, buf, buf,
-                             xdata);
+                             NULL);
         return 0;
 }
 
+dict_t*
+arbiter_fill_writev_xdata (fd_t *fd, dict_t *xdata, xlator_t *this)
+{
+        dict_t  *rsp_xdata = NULL;
+        int32_t ret = 0;
+        int is_append = 1;
+
+        if (!fd || !fd->inode || gf_uuid_is_null (fd->inode->gfid)) {
+                goto out;
+        }
+
+        if (!xdata)
+                goto out;
+
+        rsp_xdata = dict_new();
+        if (!rsp_xdata)
+                goto out;
+
+        if (dict_get (xdata, GLUSTERFS_OPEN_FD_COUNT)) {
+                ret = dict_set_uint32 (rsp_xdata, GLUSTERFS_OPEN_FD_COUNT,
+                                       fd->inode->fd_count);
+                if (ret < 0) {
+                        gf_msg_debug (this->name, 0, "Failed to set dict value"
+                                      " for GLUSTERFS_OPEN_FD_COUNT");
+                }
+        }
+        if (dict_get (xdata, GLUSTERFS_WRITE_IS_APPEND)) {
+                ret = dict_set_uint32 (rsp_xdata, GLUSTERFS_WRITE_IS_APPEND,
+                                       is_append);
+                if (ret < 0) {
+                        gf_msg_debug (this->name, 0, "Failed to set dict value"
+                                      " for GLUSTERFS_WRITE_IS_APPEND");
+                }
+        }
+out:
+        return rsp_xdata;
+}
+
 int32_t
 arbiter_writev (call_frame_t *frame, xlator_t *this, fd_t *fd,
                 struct iovec *vector, int32_t count, off_t off, uint32_t flags,
@@ -168,6 +205,7 @@ arbiter_writev (call_frame_t *frame, xlator_t *this, fd_t *fd,
 {
         arbiter_inode_ctx_t *ctx      = NULL;
         struct iatt         *buf      = NULL;
+        dict_t           *rsp_xdata   = NULL;
         int                  op_ret   = 0;
         int                  op_errno = 0;
 
@@ -179,8 +217,12 @@ arbiter_writev (call_frame_t *frame, xlator_t *this, fd_t *fd,
         }
         buf = ctx->iattbuf;
         op_ret = iov_length (vector, count);
+        rsp_xdata = arbiter_fill_writev_xdata (fd, xdata, this);
 unwind:
-        STACK_UNWIND_STRICT (writev, frame, op_ret, op_errno, buf, buf, xdata);
+        STACK_UNWIND_STRICT (writev, frame, op_ret, op_errno, buf, buf,
+                             rsp_xdata);
+        if (rsp_xdata)
+                dict_unref (rsp_xdata);
         return 0;
 }
 
@@ -201,8 +243,7 @@ arbiter_fallocate (call_frame_t *frame, xlator_t *this, fd_t *fd,
         }
         buf = ctx->iattbuf;
 unwind:
-        STACK_UNWIND_STRICT(fallocate, frame, op_ret, op_errno, buf, buf,
-                            xdata);
+        STACK_UNWIND_STRICT(fallocate, frame, op_ret, op_errno, buf, buf, NULL);
         return 0;
 }
 
@@ -223,7 +264,7 @@ arbiter_discard (call_frame_t *frame, xlator_t *this, fd_t *fd,
         }
         buf = ctx->iattbuf;
 unwind:
-        STACK_UNWIND_STRICT(discard, frame, op_ret, op_errno, buf, buf, xdata);
+        STACK_UNWIND_STRICT(discard, frame, op_ret, op_errno, buf, buf, NULL);
         return 0;
 }
 
@@ -244,7 +285,7 @@ arbiter_zerofill (call_frame_t *frame, xlator_t *this, fd_t *fd,
         }
         buf = ctx->iattbuf;
 unwind:
-        STACK_UNWIND_STRICT(zerofill, frame, op_ret, op_errno, buf, buf, xdata);
+        STACK_UNWIND_STRICT(zerofill, frame, op_ret, op_errno, buf, buf, NULL);
         return 0;
 }