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.

BUG: 1066996
Change-Id: Ibc5b80e01dc206b2abbea2d29e26f3c60ff4f204
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/7600
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Ravishankar N <ravishankar@redhat.com>

8 files changed, 164 insertions, 102 deletions

diff --git a/xlators/cluster/afr/src/afr-common.c b/xlators/cluster/afr/src/afr-common.c
index 164a651bad5..4c7692bd671 100644
--- a/xlators/cluster/afr/src/afr-common.c
+++ b/xlators/cluster/afr/src/afr-common.c
@@ -3144,6 +3144,8 @@ afr_notify (xlator_t *this, int32_t event,
         int             up_child            = -1;
         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;
 
@@ -3181,6 +3183,8 @@ 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);
@@ -3279,6 +3283,16 @@ 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++) {
diff --git a/xlators/cluster/afr/src/afr-dir-write.c b/xlators/cluster/afr/src/afr-dir-write.c
index 465dde54f9c..d59536fcb48 100644
--- a/xlators/cluster/afr/src/afr-dir-write.c
+++ b/xlators/cluster/afr/src/afr-dir-write.c
@@ -447,8 +447,6 @@ afr_create (call_frame_t *frame, xlator_t *this, loc_t *loc, int32_t flags,
 
         priv = this->private;
 
-        QUORUM_CHECK(create,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -585,8 +583,6 @@ 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)
                 goto out;
@@ -718,8 +714,6 @@ afr_mkdir (call_frame_t *frame, xlator_t *this, loc_t *loc, mode_t mode,
 
         priv = this->private;
 
-        QUORUM_CHECK(mkdir,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -849,8 +843,6 @@ afr_link (call_frame_t *frame, xlator_t *this, loc_t *oldloc, loc_t *newloc,
 
         priv = this->private;
 
-        QUORUM_CHECK(link,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -981,8 +973,6 @@ afr_symlink (call_frame_t *frame, xlator_t *this, const char *linkpath,
 
         priv = this->private;
 
-        QUORUM_CHECK(symlink,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -1116,8 +1106,6 @@ afr_rename (call_frame_t *frame, xlator_t *this, loc_t *oldloc, loc_t *newloc,
 
         priv = this->private;
 
-        QUORUM_CHECK(rename,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 op_errno = ENOMEM;
@@ -1271,8 +1259,6 @@ afr_unlink (call_frame_t *frame, xlator_t *this, loc_t *loc, int xflag,
 
         priv = this->private;
 
-        QUORUM_CHECK(unlink,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -1400,8 +1386,6 @@ afr_rmdir (call_frame_t *frame, xlator_t *this, loc_t *loc, int flags,
 
         priv = this->private;
 
-        QUORUM_CHECK(rmdir,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
diff --git a/xlators/cluster/afr/src/afr-inode-write.c b/xlators/cluster/afr/src/afr-inode-write.c
index 00e0d26768b..0c3ba920937 100644
--- a/xlators/cluster/afr/src/afr-inode-write.c
+++ b/xlators/cluster/afr/src/afr-inode-write.c
@@ -229,7 +229,7 @@ afr_writev_handle_short_writes (call_frame_t *frame, xlator_t *this)
                         continue;
 
                 if (local->replies[i].op_ret < local->op_ret)
-                        afr_transaction_fop_failed(frame, this, i);
+                        afr_transaction_fop_failed (frame, this, i);
         }
 }
 
@@ -402,14 +402,9 @@ afr_writev (call_frame_t *frame, xlator_t *this, fd_t *fd,
             struct iovec *vector, int32_t count, off_t offset,
             uint32_t flags, struct iobref *iobref, dict_t *xdata)
 {
-        afr_private_t *priv = NULL;
         afr_local_t *local = NULL;
         int op_errno = ENOMEM;
 
-        priv = this->private;
-
-        QUORUM_CHECK(writev,out);
-
 	local = AFR_FRAME_INIT (frame, op_errno);
 	if (!local)
 		goto out;
@@ -528,16 +523,11 @@ int
 afr_truncate (call_frame_t *frame, xlator_t *this,
               loc_t *loc, off_t offset, dict_t *xdata)
 {
-        afr_private_t * priv  = NULL;
         afr_local_t   * local = NULL;
         call_frame_t   *transaction_frame = NULL;
 	int ret = -1;
         int op_errno = ENOMEM;
 
-        priv = this->private;
-
-        QUORUM_CHECK(truncate,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -652,16 +642,11 @@ int
 afr_ftruncate (call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
 	       dict_t *xdata)
 {
-        afr_private_t *priv = NULL;
         afr_local_t *local = NULL;
 	call_frame_t *transaction_frame = NULL;
 	int ret = -1;
         int op_errno = ENOMEM;
 
-        priv = this->private;
-
-        QUORUM_CHECK(ftruncate,out);
-
 	transaction_frame = copy_frame (frame);
 	if (!frame)
 		goto out;
@@ -769,16 +754,11 @@ int
 afr_setattr (call_frame_t *frame, xlator_t *this, loc_t *loc, struct iatt *buf,
 	     int32_t valid, dict_t *xdata)
 {
-        afr_private_t *priv = NULL;
         afr_local_t *local = NULL;
         call_frame_t *transaction_frame = NULL;
         int ret = -1;
         int op_errno = ENOMEM;
 
-        priv = this->private;
-
-        QUORUM_CHECK(setattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -879,16 +859,11 @@ int
 afr_fsetattr (call_frame_t *frame, xlator_t *this,
               fd_t *fd, struct iatt *buf, int32_t valid, dict_t *xdata)
 {
-        afr_private_t *priv = NULL;
         afr_local_t *local = NULL;
         call_frame_t *transaction_frame = NULL;
         int ret = -1;
         int op_errno = ENOMEM;
 
-        priv = this->private;
-
-        QUORUM_CHECK(fsetattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -991,7 +966,6 @@ int
 afr_setxattr (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *dict,
 	      int32_t flags, dict_t *xdata)
 {
-        afr_private_t  *priv              = NULL;
         afr_local_t    *local             = NULL;
         call_frame_t   *transaction_frame = NULL;
         int             ret               = -1;
@@ -1003,10 +977,6 @@ afr_setxattr (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *dict,
         GF_IF_INTERNAL_XATTR_GOTO ("trusted.glusterfs.afr.*", dict,
                                    op_errno, out);
 
-        priv = this->private;
-
-        QUORUM_CHECK(setxattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -1107,7 +1077,6 @@ int
 afr_fsetxattr (call_frame_t *frame, xlator_t *this,
                fd_t *fd, dict_t *dict, int32_t flags, dict_t *xdata)
 {
-        afr_private_t    *priv              = NULL;
         afr_local_t      *local             = NULL;
         call_frame_t     *transaction_frame = NULL;
         int               ret               = -1;
@@ -1119,10 +1088,6 @@ afr_fsetxattr (call_frame_t *frame, xlator_t *this,
         GF_IF_INTERNAL_XATTR_GOTO ("trusted.glusterfs.afr.*", dict,
                                    op_errno, out);
 
-        priv = this->private;
-
-        QUORUM_CHECK(fsetxattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -1226,7 +1191,6 @@ int
 afr_removexattr (call_frame_t *frame, xlator_t *this,
                  loc_t *loc, const char *name, dict_t *xdata)
 {
-        afr_private_t   *priv              = NULL;
         afr_local_t     *local             = NULL;
         call_frame_t    *transaction_frame = NULL;
         int              ret               = -1;
@@ -1238,10 +1202,6 @@ afr_removexattr (call_frame_t *frame, xlator_t *this,
         GF_IF_NATIVE_XATTR_GOTO ("trusted.glusterfs.afr.*",
                                  name, op_errno, out);
 
-        priv = this->private;
-
-        QUORUM_CHECK(removexattr,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -1339,7 +1299,6 @@ int
 afr_fremovexattr (call_frame_t *frame, xlator_t *this, fd_t *fd,
 		  const char *name, dict_t *xdata)
 {
-	afr_private_t *priv = NULL;
         afr_local_t *local = NULL;
         call_frame_t *transaction_frame = NULL;
         int ret = -1;
@@ -1351,10 +1310,6 @@ afr_fremovexattr (call_frame_t *frame, xlator_t *this, fd_t *fd,
         GF_IF_NATIVE_XATTR_GOTO ("trusted.glusterfs.afr.*",
                                  name, op_errno, out);
 
-	priv = this->private;
-
-        QUORUM_CHECK(fremovexattr, out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -1455,16 +1410,11 @@ int
 afr_fallocate (call_frame_t *frame, xlator_t *this, fd_t *fd, int32_t mode,
                off_t offset, size_t len, dict_t *xdata)
 {
-	afr_private_t *priv = NULL;
         call_frame_t *transaction_frame = NULL;
         afr_local_t *local = NULL;
         int ret = -1;
         int op_errno = ENOMEM;
 
-	priv = this->private;
-
-        QUORUM_CHECK(fallocate,out);
-
         transaction_frame = copy_frame (frame);
         if (!transaction_frame)
                 goto out;
@@ -1573,16 +1523,11 @@ int
 afr_discard (call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
              size_t len, dict_t *xdata)
 {
-        afr_private_t *priv  = NULL;
         afr_local_t *local = NULL;
         call_frame_t *transaction_frame = NULL;
         int ret = -1;
         int op_errno = ENOMEM;
 
-        priv = this->private;
-
-        QUORUM_CHECK(discard, out);
-
 	transaction_frame = copy_frame (frame);
 	if (!transaction_frame)
 		goto out;
@@ -1687,16 +1632,11 @@ int
 afr_zerofill (call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
              size_t len, dict_t *xdata)
 {
-        afr_private_t *priv  = NULL;
         afr_local_t *local = NULL;
         call_frame_t *transaction_frame = NULL;
         int ret = -1;
         int op_errno = ENOMEM;
 
-        priv = this->private;
-
-        QUORUM_CHECK(discard, out);
-
 	transaction_frame = copy_frame (frame);
 	if (!transaction_frame)
 		goto out;
diff --git a/xlators/cluster/afr/src/afr-open.c b/xlators/cluster/afr/src/afr-open.c
index f86aa7fd80d..83da86053f4 100644
--- a/xlators/cluster/afr/src/afr-open.c
+++ b/xlators/cluster/afr/src/afr-open.c
@@ -131,10 +131,6 @@ 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);
-        }
-
 	local = AFR_FRAME_INIT (frame, op_errno);
 	if (!local)
 		goto out;
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)
 {
diff --git a/xlators/cluster/afr/src/afr-transaction.h b/xlators/cluster/afr/src/afr-transaction.h
index 77cc8eed019..c3ce333b771 100644
--- a/xlators/cluster/afr/src/afr-transaction.h
+++ b/xlators/cluster/afr/src/afr-transaction.h
@@ -49,5 +49,6 @@ int afr_read_txn_continue (call_frame_t *frame, xlator_t *this, int subvol);
 int __afr_txn_write_fop (call_frame_t *frame, xlator_t *this);
 int __afr_txn_write_done (call_frame_t *frame, xlator_t *this);
 call_frame_t *afr_transaction_detach_fop_frame (call_frame_t *frame);
+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 ead08425f2c..6af136e9163 100644
--- a/xlators/cluster/afr/src/afr.c
+++ b/xlators/cluster/afr/src/afr.c
@@ -180,6 +180,9 @@ reconfigure (xlator_t *this, dict_t *options)
         GF_OPTION_RECONF ("quorum-count", priv->quorum_count, options,
                           uint32, out);
         fix_quorum_options(this,priv,qtype);
+        if (priv->quorum_count && !afr_has_quorum (priv->child_up, this))
+                gf_log (this->name, GF_LOG_WARNING, "Client-quorum is not met");
+
 
 	GF_OPTION_RECONF ("post-op-delay-secs", priv->post_op_delay_secs, options,
 			  uint32, out);
@@ -456,9 +459,6 @@ 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,
@@ -479,6 +479,9 @@ 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 36042f7b2e5..674ea0bf72e 100644
--- a/xlators/cluster/afr/src/afr.h
+++ b/xlators/cluster/afr/src/afr.h
@@ -922,9 +922,6 @@ 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);
 
@@ -940,19 +937,6 @@ afr_filter_xattrs (dict_t *xattr);
  */
 #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);
-
 int
 afr_fd_report_unstable_write (xlator_t *this, fd_t *fd);