features/shard: Eliminate extra update to postbuf in writev

After an extending write is complete, shard translator updates postbuf
at two places:
1. shard_update_file_size_cbk(), and
2. shard_post_update_size_writev_handler().

This can lead to unexpected behavior if md-cache is part of the client
stack and caches and serves values returned by shard translator in
postbuf. This patch eliminates the update to postbuf in
shard_post_update_size_writev_handler().

Change-Id: I9d107bf57baad66886eebec14aa369b6a3c88c49
BUG: 1284365
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/12717
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>

1 files changed, 17 insertions, 16 deletions

diff --git a/xlators/features/shard/src/shard.c b/xlators/features/shard/src/shard.c
index 35c9d1d9d45..ed02f6a8c60 100644
--- a/xlators/features/shard/src/shard.c
+++ b/xlators/features/shard/src/shard.c
@@ -3360,14 +3360,11 @@ shard_post_update_size_writev_handler (call_frame_t *frame, xlator_t *this)
         if (local->op_ret < 0) {
                 SHARD_STACK_UNWIND (writev, frame, local->op_ret,
                                     local->op_errno, NULL, NULL, NULL);
-                return 0;
+        } else {
+                SHARD_STACK_UNWIND (writev, frame, local->written_size,
+                                    local->op_errno, &local->prebuf,
+                                    &local->postbuf, local->xattr_rsp);
         }
-
-        local->postbuf.ia_size += (local->delta_size + local->hole_size);
-        local->postbuf.ia_blocks += local->delta_blocks;
-
-        SHARD_STACK_UNWIND (writev, frame, local->written_size, local->op_errno,
-                            &local->prebuf, &local->postbuf, local->xattr_rsp);
         return 0;
 }
 
@@ -3423,16 +3420,20 @@ shard_writev_do_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 
         local = frame->local;
 
-        if (op_ret < 0) {
-                local->op_ret = op_ret;
-                local->op_errno = op_errno;
-        } else {
-                local->written_size += op_ret;
-                local->delta_blocks += (postbuf->ia_blocks - prebuf->ia_blocks);
-                local->delta_size += (postbuf->ia_size - prebuf->ia_size);
-                shard_inode_ctx_set (local->fd->inode, this, postbuf, 0,
-                                     SHARD_MASK_TIMES);
+        LOCK (&frame->lock);
+        {
+                if (op_ret < 0) {
+                        local->op_ret = op_ret;
+                        local->op_errno = op_errno;
+                } else {
+                        local->written_size += op_ret;
+                        local->delta_blocks += (postbuf->ia_blocks - prebuf->ia_blocks);
+                        local->delta_size += (postbuf->ia_size - prebuf->ia_size);
+                        shard_inode_ctx_set (local->fd->inode, this, postbuf, 0,
+                                             SHARD_MASK_TIMES);
+                }
         }
+        UNLOCK (&frame->lock);
 
         if (anon_fd)
                 fd_unref (anon_fd);