summaryrefslogtreecommitdiffstats
path: root/xlators/cluster/afr/src/afr-transaction.c
diff options
context:
space:
mode:
Diffstat (limited to 'xlators/cluster/afr/src/afr-transaction.c')
-rw-r--r--xlators/cluster/afr/src/afr-transaction.c144
1 files changed, 142 insertions, 2 deletions
diff --git a/xlators/cluster/afr/src/afr-transaction.c b/xlators/cluster/afr/src/afr-transaction.c
index 205ff759ef5..270e2212913 100644
--- a/xlators/cluster/afr/src/afr-transaction.c
+++ b/xlators/cluster/afr/src/afr-transaction.c
@@ -430,6 +430,135 @@ afr_handle_symmetric_errors (call_frame_t *frame, xlator_t *this)
__mark_all_success (frame, this);
}
+gf_boolean_t
+afr_has_quorum (unsigned char *subvols, xlator_t *this)
+{
+ unsigned int quorum_count = 0;
+ afr_private_t *priv = NULL;
+ unsigned int up_children_count = 0;
+
+ priv = this->private;
+ up_children_count = AFR_COUNT (subvols, priv->child_count);
+
+ if (priv->quorum_count == AFR_QUORUM_AUTO) {
+ /*
+ * Special case for even numbers of nodes in auto-quorum:
+ * if we have exactly half children up
+ * and that includes the first ("senior-most") node, then that counts
+ * as quorum even if it wouldn't otherwise. This supports e.g. N=2
+ * while preserving the critical property that there can only be one
+ * such group.
+ */
+ if ((priv->child_count % 2 == 0) &&
+ (up_children_count == (priv->child_count/2)))
+ return subvols[0];
+ }
+
+ if (priv->quorum_count == AFR_QUORUM_AUTO) {
+ quorum_count = priv->child_count/2 + 1;
+ } else {
+ quorum_count = priv->quorum_count;
+ }
+
+ if (up_children_count >= quorum_count)
+ return _gf_true;
+
+ return _gf_false;
+}
+
+static gf_boolean_t
+afr_has_fop_quorum (call_frame_t *frame)
+{
+ xlator_t *this = frame->this;
+ afr_local_t *local = frame->local;
+ unsigned char *locked_nodes = NULL;
+
+ locked_nodes = afr_locked_nodes_get (local->transaction.type,
+ &local->internal_lock);
+ return afr_has_quorum (locked_nodes, this);
+}
+
+static gf_boolean_t
+afr_has_fop_cbk_quorum (call_frame_t *frame)
+{
+ afr_local_t *local = frame->local;
+ xlator_t *this = frame->this;
+ afr_private_t *priv = this->private;
+ unsigned char *success = alloca0(priv->child_count);
+ int i = 0;
+
+ for (i = 0; i < priv->child_count; i++) {
+ if (local->transaction.pre_op[i])
+ if (!local->transaction.failed_subvols[i])
+ success[i] = 1;
+ }
+
+ return afr_has_quorum (success, this);
+}
+
+void
+afr_handle_quorum (call_frame_t *frame)
+{
+ afr_local_t *local = NULL;
+ afr_private_t *priv = NULL;
+ int i = 0;
+ const char *file = NULL;
+ uuid_t gfid = {0};
+
+ local = frame->local;
+ priv = frame->this->private;
+
+ if (priv->quorum_count == 0)
+ return;
+
+ /*
+ * Network split may happen just after the fops are unwound, so check
+ * if the fop succeeded in a way it still follows quorum. If it doesn't,
+ * mark the fop as failure, mark the changelogs so it reflects that
+ * failure.
+ *
+ * Scenario:
+ * There are 3 mounts on 3 machines(node1, node2, node3) all writing to
+ * single file. Network split happened in a way that node1 can't see
+ * node2, node3. Node2, node3 both of them can't see node1. Now at the
+ * time of sending write all the bricks are up. Just after write fop is
+ * wound on node1, network split happens. Node1 thinks write fop failed
+ * on node2, node3 so marks pending changelog for those 2 extended
+ * attributes on node1. Node2, node3 thinks writes failed on node1 so
+ * they mark pending changelog for node1. When the network is stable
+ * again the file already is in split-brain. These checks prevent
+ * marking pending changelog on other subvolumes if the fop doesn't
+ * succeed in a way it is still following quorum. So with this fix what
+ * is happening is, node1 will have all pending changelog(FOOL) because
+ * the write succeeded only on node1 but failed on node2, node3 so
+ * instead of marking pending changelogs on node2, node3 it just treats
+ * the fop as failure and goes into DIRTY state. Where as node2, node3
+ * say they are sources and have pending changelog to node1 so there is
+ * no split-brain with the fix. The problem is eliminated completely.
+ */
+
+ if (afr_has_fop_cbk_quorum (frame))
+ return;
+
+ if (local->fd) {
+ uuid_copy (gfid, local->fd->inode->gfid);
+ file = uuid_utoa (gfid);
+ } else {
+ loc_path (&local->loc, local->loc.name);
+ file = local->loc.path;
+ }
+
+ gf_log (frame->this->name, GF_LOG_WARNING, "%s: Failing %s as quorum "
+ "is not met", file, gf_fop_list[local->op]);
+
+ for (i = 0; i < priv->child_count; i++) {
+ if (local->transaction.pre_op[i])
+ afr_transaction_fop_failed (frame, frame->this, i);
+ }
+
+ local->op_ret = -1;
+ local->op_errno = EROFS;
+}
int
afr_changelog_post_op_now (call_frame_t *frame, xlator_t *this)
@@ -443,6 +572,7 @@ afr_changelog_post_op_now (call_frame_t *frame, xlator_t *this)
int nothing_failed = 1;
gf_boolean_t need_undirty = _gf_false;
+ afr_handle_quorum (frame);
local = frame->local;
idx = afr_index_for_transaction_type (local->transaction.type);
@@ -453,6 +583,14 @@ afr_changelog_post_op_now (call_frame_t *frame, xlator_t *this)
else
need_undirty = _gf_true;
+ //If the fop fails on all the subvols then pending markers are placed
+ //for every subvol on all subvolumes. Which is nothing but split-brain.
+ //Avoid this by not doing post-op in case of failures.
+ if (local->op_ret < 0) {
+ afr_changelog_post_op_done (frame, this);
+ goto out;
+ }
+
if (nothing_failed && !need_undirty) {
afr_changelog_post_op_done (frame, this);
goto out;
@@ -842,7 +980,10 @@ afr_changelog_pre_op (call_frame_t *frame, xlator_t *this)
}
}
- /* TBD: quorum check w/ call_count */
+ if (priv->quorum_count && !afr_has_fop_quorum (frame)) {
+ op_errno = EROFS;
+ goto err;
+ }
if (call_count == 0) {
op_errno = ENOTCONN;
@@ -1057,7 +1198,6 @@ afr_post_blocking_rename_cbk (call_frame_t *frame, xlator_t *this)
return 0;
}
-
int
afr_post_lower_unlock_cbk (call_frame_t *frame, xlator_t *this)
{