cluster/afr: Fix bugs in quorum implementation

- Have common place to perform quorum fop wind check
- Check if fop succeeded in a way that matches quorum
  to avoid marking changelog in split-brain.

Change-Id: I663072ece0e1de6e1ee9fccb03e1b6c968793bc5
BUG: 1066996
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/7513
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>

8 files changed, 166 insertions, 103 deletions

diff --git a/xlators/cluster/afr/src/afr-common.c b/xlators/cluster/afr/src/afr-common.c
index 2a54a79ed4a..a31cc2cb015 100644
--- a/xlators/cluster/afr/src/afr-common.c
+++ b/xlators/cluster/afr/src/afr-common.c
@@ -4034,6 +4034,8 @@ afr_notify (xlator_t *this, int32_t event,
         int             up_child            = AFR_ALL_CHILDREN;
         dict_t          *input              = NULL;
         dict_t          *output             = NULL;
+        gf_boolean_t    had_quorum          = _gf_false;
+        gf_boolean_t    has_quorum          = _gf_false;
 
         priv = this->private;
 
@@ -4071,6 +4073,8 @@ afr_notify (xlator_t *this, int32_t event,
                 goto out;
         }
 
+        had_quorum = priv->quorum_count && afr_has_quorum (priv->child_up,
+                                                           this);
         switch (event) {
         case GF_EVENT_CHILD_UP:
                 LOCK (&priv->lock);
@@ -4163,6 +4167,16 @@ afr_notify (xlator_t *this, int32_t event,
                 break;
         }
 
+        if (priv->quorum_count) {
+                has_quorum = afr_has_quorum (priv->child_up, this);
+                if (!had_quorum && has_quorum)
+                        gf_log (this->name, GF_LOG_INFO, "Client-quorum"
+                                " is met");
+                if (had_quorum && !has_quorum)
+                        gf_log (this->name, GF_LOG_WARNING,
+                                "Client-quorum is not met");
+        }
+
         /* have all subvolumes reported status once by now? */
         have_heard_from_all = 1;
         for (i = 0; i < priv->child_count; i++) {
@@ -4546,43 +4560,6 @@ out:
         return ret;
 }
 
-gf_boolean_t
-afr_have_quorum (char *logname, afr_private_t *priv)
-{
-        unsigned int        quorum = 0;
-
-        GF_VALIDATE_OR_GOTO(logname,priv,out);
-
-        quorum = priv->quorum_count;
-        if (quorum != AFR_QUORUM_AUTO) {
-                return (priv->up_count >= (priv->down_count + quorum));
-        }
-
-        quorum = priv->child_count / 2 + 1;
-        if (priv->up_count >= (priv->down_count + quorum)) {
-                return _gf_true;
-        }
-
-        /*
-         * Special case for even numbers of nodes: if we have exactly half
-         * 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) {
-                quorum = priv->child_count / 2;
-                if (priv->up_count >= (priv->down_count + quorum)) {
-                        if (priv->child_up[0]) {
-                                return _gf_true;
-                        }
-                }
-        }
-
-out:
-        return _gf_false;
-}
-
 void
 afr_priv_destroy (afr_private_t *priv)
 {
diff --git a/xlators/cluster/afr/src/afr-dir-write.c b/xlators/cluster/afr/src/afr-dir-write.c
index 1943b719bb5..3cdec64536d 100644
--- a/xlators/cluster/afr/src/afr-dir-write.c
+++ b/xlators/cluster/afr/src/afr-dir-write.c
@@ -432,8 +432,6 @@ afr_create (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(create,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -637,8 +635,6 @@ afr_mknod (call_frame_t *frame, xlator_t *this, loc_t *loc, mode_t mode,
 
         priv = this->private;
 
-        QUORUM_CHECK(mknod,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -842,8 +838,6 @@ afr_mkdir (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(mkdir,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1046,8 +1040,6 @@ afr_link (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(link,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1249,8 +1241,6 @@ afr_symlink (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(symlink,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1464,8 +1454,6 @@ afr_rename (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(rename,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1685,8 +1673,6 @@ afr_unlink (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(unlink,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1889,8 +1875,6 @@ afr_rmdir (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(rmdir,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
diff --git a/xlators/cluster/afr/src/afr-inode-write.c b/xlators/cluster/afr/src/afr-inode-write.c
index d62847defa3..5561e9c36d7 100644
--- a/xlators/cluster/afr/src/afr-inode-write.c
+++ b/xlators/cluster/afr/src/afr-inode-write.c
@@ -548,8 +548,6 @@ afr_writev (call_frame_t *frame, xlator_t *this, fd_t *fd,
                 goto out;
         }
 
-        QUORUM_CHECK(writev,out);
-
         AFR_LOCAL_ALLOC_OR_GOTO (frame->local, out);
         local = frame->local;
 
@@ -730,8 +728,6 @@ afr_truncate (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(truncate,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -745,6 +741,7 @@ afr_truncate (call_frame_t *frame, xlator_t *this,
         if (ret < 0)
                 goto out;
 
+        local->op = GF_FOP_TRUNCATE;
         local->cont.truncate.offset  = offset;
 
         local->transaction.fop    = afr_truncate_wind;
@@ -974,8 +971,6 @@ afr_ftruncate (call_frame_t *frame, xlator_t *this,
                 op_errno = EIO;
                 goto out;
         }
-        QUORUM_CHECK(ftruncate,out);
-
         AFR_LOCAL_ALLOC_OR_GOTO (frame->local, out);
         local = frame->local;
 
@@ -1153,8 +1148,6 @@ afr_setattr (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(setattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1168,6 +1161,7 @@ afr_setattr (call_frame_t *frame, xlator_t *this,
         if (ret < 0)
                 goto out;
 
+        local->op = GF_FOP_SETATTR;
         local->cont.setattr.in_buf = *buf;
         local->cont.setattr.valid  = valid;
 
@@ -1351,8 +1345,6 @@ afr_fsetattr (call_frame_t *frame, xlator_t *this,
                 goto out;
         }
 
-        QUORUM_CHECK(fsetattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1366,6 +1358,7 @@ afr_fsetattr (call_frame_t *frame, xlator_t *this,
         if (ret < 0)
                 goto out;
 
+        local->op = GF_FOP_FSETATTR;
         local->cont.fsetattr.in_buf = *buf;
         local->cont.fsetattr.valid  = valid;
 
@@ -1540,7 +1533,6 @@ afr_setxattr (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(setxattr,out);
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1554,6 +1546,7 @@ afr_setxattr (call_frame_t *frame, xlator_t *this,
         if (ret < 0)
                 goto out;
 
+        local->op = GF_FOP_SETXATTR;
         local->cont.setxattr.dict  = dict_ref (dict);
         local->cont.setxattr.flags = flags;
 
@@ -1730,8 +1723,6 @@ afr_fsetxattr (call_frame_t *frame, xlator_t *this,
                 goto out;
         }
 
-        QUORUM_CHECK(fsetxattr,out);
-
         AFR_LOCAL_ALLOC_OR_GOTO (local, out);
 
         ret = afr_local_init (local, priv, &op_errno);
@@ -1747,6 +1738,7 @@ afr_fsetxattr (call_frame_t *frame, xlator_t *this,
 
         local->op_ret = -1;
 
+        local->op = GF_FOP_FSETXATTR;
         local->cont.fsetxattr.dict  = dict_ref (dict);
         local->cont.fsetxattr.flags = flags;
 
@@ -1922,8 +1914,6 @@ afr_removexattr (call_frame_t *frame, xlator_t *this,
 
         priv = this->private;
 
-        QUORUM_CHECK(removexattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 op_errno = ENOMEM;
@@ -1937,6 +1927,7 @@ afr_removexattr (call_frame_t *frame, xlator_t *this,
         if (ret < 0)
                 goto out;
 
+        local->op = GF_FOP_REMOVEXATTR;
         local->cont.removexattr.name = gf_strdup (name);
 
         local->transaction.fop    = afr_removexattr_wind;
@@ -2111,8 +2102,6 @@ afr_fremovexattr (call_frame_t *frame, xlator_t *this,
                 goto out;
         }
 
-        QUORUM_CHECK(fremovexattr, out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame) {
                 goto out;
@@ -2130,6 +2119,7 @@ afr_fremovexattr (call_frame_t *frame, xlator_t *this,
 
         local->op_ret = -1;
 
+        local->op = GF_FOP_FREMOVEXATTR;
         local->cont.removexattr.name = gf_strdup (name);
 
         local->transaction.fop    = afr_fremovexattr_wind;
@@ -2354,8 +2344,6 @@ afr_fallocate (call_frame_t *frame, xlator_t *this, fd_t *fd, int32_t mode,
                 op_errno = EIO;
                 goto out;
         }
-        QUORUM_CHECK(fallocate,out);
-
         AFR_LOCAL_ALLOC_OR_GOTO (frame->local, out);
         local = frame->local;
 
@@ -2581,8 +2569,6 @@ afr_discard (call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
                 op_errno = EIO;
                 goto out;
         }
-        QUORUM_CHECK(discard, out);
-
         AFR_LOCAL_ALLOC_OR_GOTO (frame->local, out);
         local = frame->local;
 
@@ -2825,8 +2811,6 @@ afr_zerofill (call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
                 op_errno = EIO;
                 goto out;
         }
-        QUORUM_CHECK(zerofill, out);
-
         AFR_LOCAL_ALLOC_OR_GOTO (frame->local, out);
         local = frame->local;
 
diff --git a/xlators/cluster/afr/src/afr-open.c b/xlators/cluster/afr/src/afr-open.c
index 643a5d692df..9404b6e847b 100644
--- a/xlators/cluster/afr/src/afr-open.c
+++ b/xlators/cluster/afr/src/afr-open.c
@@ -203,10 +203,6 @@ afr_open (call_frame_t *frame, xlator_t *this, loc_t *loc, int32_t flags,
 
         priv = this->private;
 
-        if (flags & (O_CREAT|O_TRUNC)) {
-                QUORUM_CHECK(open,out);
-        }
-
         if (afr_is_split_brain (this, loc->inode)) {
                 /* self-heal failed */
                 gf_log (this->name, GF_LOG_WARNING,
diff --git a/xlators/cluster/afr/src/afr-transaction.c b/xlators/cluster/afr/src/afr-transaction.c
index 20306e46924..91af75b503b 100644
--- a/xlators/cluster/afr/src/afr-transaction.c
+++ b/xlators/cluster/afr/src/afr-transaction.c
@@ -640,6 +640,131 @@ afr_data_handle_quota_errors (call_frame_t *frame, xlator_t *this)
                                     local->transaction.type);
 }
 
+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_up_children_count (subvols, priv->child_count);
+
+        if (priv->quorum_count == AFR_QUORUM_AUTO) {
+                quorum_count = priv->child_count/2 + 1;
+        } else {
+                quorum_count = priv->quorum_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 (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 = alloca(priv->child_count);
+        int           i        = 0;
+        int           j        = 0;
+
+        j = afr_index_for_transaction_type (local->transaction.type);
+        for (i = 0; i < priv->child_count; i++) {
+                if (local->pending[i][j])
+                        success[i] = 1;
+                else
+                        success[i] = 0;
+        }
+
+        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;
+        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 FOOL 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);
+        else
+                loc_gfid (&local->loc, gfid);
+
+        gf_log (frame->this->name, GF_LOG_WARNING, "%s: Failing %s as quorum "
+                "is not met", uuid_utoa (gfid), gf_fop_list[local->op]);
+        for (i = 0; i < priv->child_count; i++)
+                __mark_child_dead (local->pending, priv->child_count, i,
+                                   local->transaction.type);
+        local->op_ret = -1;
+        local->op_errno = EROFS;
+}
+
 int
 afr_changelog_post_op_now (call_frame_t *frame, xlator_t *this)
 {
@@ -663,6 +788,7 @@ afr_changelog_post_op_now (call_frame_t *frame, xlator_t *this)
 
         afr_data_handle_quota_errors (frame, this);
         afr_dir_fop_handle_all_fop_failures (frame);
+        afr_handle_quorum (frame);
 
         if (local->fd)
                 afr_transaction_rm_stale_children (frame, this,
@@ -1320,12 +1446,24 @@ afr_lock (call_frame_t *frame, xlator_t *this)
 int
 afr_internal_lock_finish (call_frame_t *frame, xlator_t *this)
 {
+        afr_local_t     *local = frame->local;
+        afr_private_t   *priv  = this->private;
+
+        if (priv->quorum_count && !afr_has_fop_quorum (frame)) {
+                local->op_ret = -1;
+                local->op_errno = EROFS;
+                local->internal_lock.lock_cbk = local->transaction.done;
+                afr_unlock (frame, this);
+                goto out;
+        }
+
         if (__fop_changelog_needed (frame, this)) {
                 afr_changelog_pre_op (frame, this);
         } else {
                 afr_transaction_perform_fop (frame, this);
         }
 
+out:
         return 0;
 }
 
@@ -1833,9 +1971,7 @@ afr_transaction_fop_failed (call_frame_t *frame, xlator_t *this,
                         child_index, local->transaction.type);
 }
 
-
-
-        static gf_boolean_t
+static gf_boolean_t
 afr_locals_overlap (afr_local_t *local1, afr_local_t *local2)
 {
         uint64_t start1 = local1->transaction.start;
diff --git a/xlators/cluster/afr/src/afr-transaction.h b/xlators/cluster/afr/src/afr-transaction.h
index fa626fd0d6e..bcc40db99d3 100644
--- a/xlators/cluster/afr/src/afr-transaction.h
+++ b/xlators/cluster/afr/src/afr-transaction.h
@@ -48,4 +48,7 @@ afr_any_fops_failed (afr_local_t *local, afr_private_t *priv);
 
 gf_boolean_t
 afr_txn_nothing_failed (call_frame_t *frame, xlator_t *this);
+
+gf_boolean_t
+afr_has_quorum (unsigned char *subvols, xlator_t *this);
 #endif /* __TRANSACTION_H__ */
diff --git a/xlators/cluster/afr/src/afr.c b/xlators/cluster/afr/src/afr.c
index c724eb2ae42..c020cbccac5 100644
--- a/xlators/cluster/afr/src/afr.c
+++ b/xlators/cluster/afr/src/afr.c
@@ -497,9 +497,6 @@ struct xlator_fops fops = {
         .finodelk    = afr_finodelk,
         .entrylk     = afr_entrylk,
         .fentrylk    = afr_fentrylk,
-	.fallocate   = afr_fallocate,
-	.discard     = afr_discard,
-        .zerofill    = afr_zerofill,
 
         /* inode read */
         .access      = afr_access,
@@ -520,6 +517,9 @@ struct xlator_fops fops = {
         .fsetattr    = afr_fsetattr,
         .removexattr = afr_removexattr,
         .fremovexattr = afr_fremovexattr,
+        .fallocate   = afr_fallocate,
+        .discard     = afr_discard,
+        .zerofill    = afr_zerofill,
 
         /* dir read */
         .opendir     = afr_opendir,
diff --git a/xlators/cluster/afr/src/afr.h b/xlators/cluster/afr/src/afr.h
index e86300d0a22..59d08a1d0b7 100644
--- a/xlators/cluster/afr/src/afr.h
+++ b/xlators/cluster/afr/src/afr.h
@@ -1136,9 +1136,6 @@ int
 afr_child_fd_ctx_set (xlator_t *this, fd_t *fd, int32_t child,
                       int flags);
 
-gf_boolean_t
-afr_have_quorum (char *logname, afr_private_t *priv);
-
 void
 afr_matrix_cleanup (int32_t **pending, unsigned int m);
 
@@ -1167,20 +1164,6 @@ afr_xattr_array_destroy (dict_t **xattr, unsigned int child_count);
  */
 #define AFR_QUORUM_AUTO INT_MAX
 
-/*
- * Having this as a macro will make debugging a bit weirder, but does reduce
- * the probability of functions handling this check inconsistently.
- */
-#define QUORUM_CHECK(_func,_label) do {                                  \
-        if (priv->quorum_count && !afr_have_quorum(this->name,priv)) { \
-                gf_log(this->name,GF_LOG_WARNING,                        \
-                       "failing "#_func" due to lack of quorum");        \
-                op_errno = EROFS;                                        \
-                goto _label;                                             \
-        }                                                                \
-} while (0);
-
-
 #define AFR_SBRAIN_MSG "Failed on %s as split-brain is seen. Returning EIO."
 
 #define AFR_SBRAIN_CHECK_FD(fd, label) do {                              \