diff options
Diffstat (limited to 'xlators/cluster/afr/src/afr-transaction.c')
| -rw-r--r-- | xlators/cluster/afr/src/afr-transaction.c | 144 |
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) { |