afr: don't update readables if inode refresh failed on all children

Problem:
If inode refresh failed on all children of afr due to ENOENT (say file
migrated by dht), it resets the readables to zero. Any inflight txn which
then later comes on the inode fails with EIO because no readable
children present for the inode.

Fix:
Don't update readables when inode refresh fails on *all* children of
afr. In that way any inflight txns will either proceed with its own inode
refresh if needed and fail it with the right errno or use the old value
of readables and continue with the txn.

Also, add quorum checks to the beginning of afr_transaction(). Otherwise, we
seem to be winding the lock and checking for quorum only in pre-op pahse.

Note: This should ideally fix BZ 1329505 since the stop gap fix for
it is has been reverted at https://review.gluster.org/#/c/20028.

Change-Id: Ia638c092d8d12dc27afb3cdad133394845061319
updates: bz#1584483
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

1 files changed, 40 insertions, 27 deletions

diff --git a/xlators/cluster/afr/src/afr-common.c b/xlators/cluster/afr/src/afr-common.c
index ad037cd7060..1e0c1a7b265 100644
--- a/xlators/cluster/afr/src/afr-common.c
+++ b/xlators/cluster/afr/src/afr-common.c
@@ -1176,7 +1176,7 @@ afr_inode_refresh_err (call_frame_t *frame, xlator_t *this)
 
 	err = afr_final_errno (local, priv);
 ret:
-	return -err;
+	return err;
 }
 
 gf_boolean_t
@@ -1226,31 +1226,31 @@ afr_txn_refresh_done (call_frame_t *frame, xlator_t *this, int err)
         if (ret == -EIO || (local->is_read_txn && !event_generation)) {
                 /* No readable subvolume even after refresh ==> splitbrain.*/
                 if (!priv->fav_child_policy) {
-                        err = -EIO;
+                        err = EIO;
                         goto refresh_done;
                 }
                 read_subvol = afr_sh_get_fav_by_policy (this, local->replies,
                                                         inode, NULL);
                 if (read_subvol == -1) {
-                        err = -EIO;
+                        err = EIO;
                         goto refresh_done;
                 }
 
                 heal_frame = copy_frame (frame);
                 if (!heal_frame) {
-                        err = -EIO;
+                        err = EIO;
                         goto refresh_done;
                 }
                 heal_frame->root->pid = GF_CLIENT_PID_SELF_HEALD;
                 heal_local = AFR_FRAME_INIT (heal_frame, op_errno);
                 if (!heal_local) {
-                        err = -EIO;
+                        err = EIO;
                         AFR_STACK_DESTROY (heal_frame);
                         goto refresh_done;
                 }
                 heal_local->xdata_req = dict_new();
                 if (!heal_local->xdata_req) {
-                        err = -EIO;
+                        err = EIO;
                         AFR_STACK_DESTROY (heal_frame);
                         goto refresh_done;
                 }
@@ -1270,29 +1270,49 @@ refresh_done:
         return 0;
 }
 
+static void
+afr_fill_success_replies (afr_local_t *local, afr_private_t *priv,
+                          unsigned char *replies)
+{
+        int i = 0;
+
+        for (i = 0; i < priv->child_count; i++) {
+                if (local->replies[i].valid && local->replies[i].op_ret == 0)
+                        replies[i] = 1;
+        }
+}
+
 int
 afr_inode_refresh_done (call_frame_t *frame, xlator_t *this, int error)
 {
 	call_frame_t *heal_frame = NULL;
 	afr_local_t *local = NULL;
+        afr_private_t *priv = NULL;
         gf_boolean_t start_heal = _gf_false;
         afr_local_t *heal_local = NULL;
+        unsigned char *success_replies = NULL;
         int op_errno = ENOMEM;
 	int ret = 0;
-	int err = 0;
 
 	if (error != 0) {
-		err = error;
 		goto refresh_done;
 	}
 
 	local = frame->local;
+        priv = this->private;
+        success_replies = alloca0 (priv->child_count);
+        afr_fill_success_replies (local, priv, success_replies);
+
+        if (!afr_has_quorum (success_replies, this)) {
+                error = afr_final_errno (frame->local, this->private);
+                if (!error)
+                        error = afr_quorum_errno(priv);
+                goto refresh_done;
+        }
 
 	ret = afr_replies_interpret (frame, this, local->refreshinode,
                                      &start_heal);
 
-	err = afr_inode_refresh_err (frame, this);
-
 	if (ret && afr_selfheal_enabled (this) && start_heal) {
                 heal_frame = copy_frame (frame);
                 if (!heal_frame)
@@ -1312,7 +1332,7 @@ afr_inode_refresh_done (call_frame_t *frame, xlator_t *this, int error)
         }
 
 refresh_done:
-        afr_txn_refresh_done (frame, this, err);
+        afr_txn_refresh_done (frame, this, error);
 
 	return 0;
 }
@@ -1326,7 +1346,7 @@ afr_inode_refresh_subvol_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         int call_child = (long) cookie;
         int8_t need_heal = 1;
         int call_count = 0;
-        GF_UNUSED int ret = 0;
+        int ret = 0;
 
         local = frame->local;
         local->replies[call_child].valid = 1;
@@ -1349,7 +1369,8 @@ afr_inode_refresh_subvol_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         call_count = afr_frame_return (frame);
         if (call_count == 0) {
                 afr_set_need_heal (this, local);
-		afr_inode_refresh_done (frame, this, 0);
+                ret = afr_inode_refresh_err (frame, this);
+		afr_inode_refresh_done (frame, this, ret);
         }
 
 }
@@ -2359,9 +2380,7 @@ afr_lookup_done (call_frame_t *frame, xlator_t *this)
 	local->op_errno = op_errno;
 
 	read_subvol = -1;
-        for (i = 0; i < priv->child_count; i++)
-                if (replies[i].valid && replies[i].op_ret == 0)
-                        success_replies[i] = 1;
+        afr_fill_success_replies (local, priv, success_replies);
 
 	for (i = 0; i < priv->child_count; i++) {
 		if (!replies[i].valid)
@@ -2906,7 +2925,6 @@ afr_discover_unwind (call_frame_t *frame, xlator_t *this)
 {
         afr_private_t       *priv  = NULL;
         afr_local_t         *local = NULL;
-	int                 i = -1;
 	int                 op_errno = 0;
 	int                 read_subvol = -1;
         unsigned char *data_readable = NULL;
@@ -2917,14 +2935,9 @@ afr_discover_unwind (call_frame_t *frame, xlator_t *this)
         data_readable = alloca0 (priv->child_count);
         success_replies = alloca0 (priv->child_count);
 
-	for (i = 0; i < priv->child_count; i++) {
-		if (!local->replies[i].valid)
-			continue;
-		if (local->replies[i].op_ret == 0) {
-                        success_replies[i] = 1;
-			local->op_ret = 0;
-                }
-	}
+        afr_fill_success_replies (local, priv, success_replies);
+        if (AFR_COUNT (success_replies, priv->child_count) > 0)
+                local->op_ret = 0;
 
 	op_errno = afr_final_errno (frame->local, this->private);
 
@@ -3101,7 +3114,7 @@ afr_discover_do (call_frame_t *frame, xlator_t *this, int err)
 	priv = this->private;
 
 	if (err) {
-		local->op_errno = -err;
+		local->op_errno = err;
 		goto out;
 	}
 
@@ -3214,7 +3227,7 @@ afr_lookup_do (call_frame_t *frame, xlator_t *this, int err)
 	priv = this->private;
 
 	if (err < 0) {
-		local->op_errno = -err;
+		local->op_errno = err;
 		ret = -1;
 		goto out;
 	}