afr: add quorum checks in pre-op

Backport of https://review.gluster.org/#/c/19781/

Problem:
We seem to be winding the FOP if pre-op did not succeed on quorum bricks
and then failing the FOP with EROFS since the fop did not meet quorum.
This essentially masks the actual error due to which pre-op failed. (See
BZ).

Fix:
Skip FOP phase if pre-op quorum is not met and go to post-op.

Change-Id: Ie58a41e8fa1ad79aa06093706e96db8eef61b6d9
BUG: 1597154
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

1 files changed, 31 insertions, 29 deletions

diff --git a/xlators/cluster/afr/src/afr-transaction.c b/xlators/cluster/afr/src/afr-transaction.c
index 19740e18b18..98886246df4 100644
--- a/xlators/cluster/afr/src/afr-transaction.c
+++ b/xlators/cluster/afr/src/afr-transaction.c
@@ -137,6 +137,29 @@ afr_needs_changelog_update (afr_local_t *local)
         return _gf_false;
 }
 
+gf_boolean_t
+afr_changelog_has_quorum (afr_local_t *local, xlator_t *this)
+{
+        afr_private_t *priv = NULL;
+        int i = 0;
+        unsigned char *success_children = NULL;
+
+        priv = this->private;
+        success_children = alloca0 (priv->child_count);
+
+        for (i = 0; i < priv->child_count; i++) {
+                if (!local->transaction.failed_subvols[i]) {
+                        success_children[i] = 1;
+                }
+        }
+
+        if (afr_has_quorum (success_children, this)) {
+                return _gf_true;
+        }
+
+        return _gf_false;
+}
+
 int
 __afr_txn_write_fop (call_frame_t *frame, xlator_t *this)
 {
@@ -154,7 +177,10 @@ __afr_txn_write_fop (call_frame_t *frame, xlator_t *this)
         call_count = priv->child_count - AFR_COUNT (failed_subvols,
                                                     priv->child_count);
 
-        if (call_count == 0) {
+        /* Fail if pre-op did not succeed on quorum no. of bricks. */
+        if (!afr_changelog_has_quorum (local, this) || !call_count) {
+                local->op_ret = -1;
+                /* local->op_errno is already captured in changelog cbk. */
                 local->transaction.resume (frame, this);
                 return 0;
         }
@@ -533,33 +559,6 @@ afr_lock_server_count (afr_private_t *priv, afr_transaction_type type)
 
 /* {{{ pending */
 
-
-void
-afr_handle_post_op_quorum (afr_local_t *local, xlator_t *this)
-{
-        afr_private_t *priv = NULL;
-        int i = 0;
-        unsigned char *post_op_children = NULL;
-
-        priv = this->private;
-        post_op_children = alloca0 (priv->child_count);
-
-        for (i = 0; i < priv->child_count; i++) {
-                if (!local->transaction.failed_subvols[i]) {
-                        post_op_children[i] = 1;
-                }
-        }
-
-        if (afr_has_quorum (post_op_children, this)) {
-                return;
-        }
-
-        local->op_ret = -1;
-        /*local->op_errno is already captured in post-op callback.*/
-
-        return;
-}
-
 int
 afr_changelog_post_op_done (call_frame_t *frame, xlator_t *this)
 {
@@ -572,7 +571,10 @@ afr_changelog_post_op_done (call_frame_t *frame, xlator_t *this)
         int_lock = &local->internal_lock;
 
         /* Fail the FOP if post-op did not succeed on quorum no. of bricks. */
-        afr_handle_post_op_quorum (local, this);
+        if (!afr_changelog_has_quorum (local, this)) {
+                local->op_ret = -1;
+                /*local->op_errno is already captured in changelog cbk*/
+        }
 
 	if (local->transaction.resume_stub) {
 		call_resume (local->transaction.resume_stub);