cluster/afr: Modified split-brain handling

RCA
The bug is observed because the decision to mark
a file in split-brain is taken outside appropriate locks.
Lookup gathers xattrs outside any lock. The xattrs being
in split-brain in lookup should only be taken as a hint.
Appropriate inodelks should be taken before confirming
a split-brain. Self-heal confirms this at the moment.
If data/metadata self-heal is turned off, inspecting of
xattrs could not be performed so split-brain behavior
does not work correctly if the self-heal options are turned off.

Fix
Self-heals are launched to inspect xattrs even when the
data/metadata self-heal options are turned off. The decision
to heal data/metadata after the xattrs are inspected is based
on whether the options are turned on/off. So decision to set/reset
split-brain flag is taken inside appropriate locks.

Testcases:
tests 33-36 in
https://github.com/pranithk/gluster-tests/blob/master/afr/self-heal.sh

Change-Id: Ia8aeab08208b50c06609ad35a9d72f3d553ee343
BUG: 833727
Signed-off-by: Pranith Kumar K <pranithk@gluster.com>
Reviewed-on: http://review.gluster.com/3626
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

5 files changed, 146 insertions, 57 deletions

diff --git a/xlators/cluster/afr/src/afr-common.c b/xlators/cluster/afr/src/afr-common.c
index b6e16074364..70a9cd35463 100644
--- a/xlators/cluster/afr/src/afr-common.c
+++ b/xlators/cluster/afr/src/afr-common.c
@@ -908,6 +908,8 @@ afr_local_cleanup (afr_local_t *local, xlator_t *this)
                 GF_FREE (local->cont.lookup.success_children);
 
                 GF_FREE (local->cont.lookup.sources);
+                afr_matrix_cleanup (local->cont.lookup.pending_matrix,
+                                    priv->child_count);
         }
 
         { /* getxattr */
@@ -1181,6 +1183,36 @@ afr_lookup_set_self_heal_params_by_xattr (afr_local_t *local, xlator_t *this,
         }
 }
 
+void
+afr_lookup_check_set_metadata_split_brain (afr_local_t *local, xlator_t *this)
+{
+        int32_t                  *sources = NULL;
+        afr_private_t            *priv = NULL;
+        int32_t                  subvol_status = 0;
+        int32_t                  *success_children   = NULL;
+        dict_t                   **xattrs = NULL;
+        struct iatt              *bufs = NULL;
+        int32_t                  **pending_matrix = NULL;
+
+        priv = this->private;
+
+        sources = GF_CALLOC (priv->child_count, sizeof (*sources),
+                             gf_afr_mt_int32_t);
+        if (NULL == sources)
+                goto out;
+        success_children = local->cont.lookup.success_children;
+        xattrs = local->cont.lookup.xattrs;
+        bufs = local->cont.lookup.bufs;
+        pending_matrix = local->cont.lookup.pending_matrix;
+        afr_build_sources (this, xattrs, bufs, pending_matrix,
+                           sources, success_children, AFR_METADATA_TRANSACTION,
+                           &subvol_status, _gf_false);
+        if (subvol_status & SPLIT_BRAIN)
+                local->cont.lookup.possible_spb = _gf_true;
+out:
+        GF_FREE (sources);
+}
+
 static void
 afr_detect_self_heal_by_iatt (afr_local_t *local, xlator_t *this,
                             struct iatt *buf, struct iatt *lookup_buf)
@@ -1214,8 +1246,26 @@ afr_detect_self_heal_by_iatt (afr_local_t *local, xlator_t *this,
 }
 
 static void
-afr_detect_self_heal_by_lookup_status (afr_local_t *local, xlator_t *this,
-                                       gf_boolean_t split_brain)
+afr_detect_self_heal_by_split_brain_status (afr_local_t *local, xlator_t *this)
+{
+        gf_boolean_t split_brain = _gf_false;
+        afr_self_heal_t *sh = NULL;
+
+        sh = &local->self_heal;
+
+        split_brain = afr_is_split_brain (this, local->cont.lookup.inode);
+        split_brain = split_brain || local->cont.lookup.possible_spb;
+        if ((local->success_count > 0) && split_brain &&
+            IA_ISREG (local->cont.lookup.inode->ia_type)) {
+                sh->force_confirm_spb = _gf_true;
+                gf_log (this->name, GF_LOG_WARNING,
+                        "split brain detected during lookup of %s.",
+                        local->loc.path);
+        }
+}
+
+static void
+afr_detect_self_heal_by_lookup_status (afr_local_t *local, xlator_t *this)
 {
         GF_ASSERT (local);
         GF_ASSERT (this);
@@ -1233,15 +1283,6 @@ afr_detect_self_heal_by_lookup_status (afr_local_t *local, xlator_t *this,
                 goto out;
         }
 
-        if ((local->success_count > 0) && split_brain &&
-            IA_ISREG (local->cont.lookup.inode->ia_type)) {
-                local->self_heal.do_data_self_heal = _gf_true;
-                local->self_heal.do_gfid_self_heal    = _gf_true;
-                gf_log (this->name, GF_LOG_WARNING,
-                        "split brain detected during lookup of %s.",
-                        local->loc.path);
-        }
-
 out:
         return;
 }
@@ -1252,6 +1293,8 @@ afr_can_self_heal_proceed (afr_self_heal_t *sh, afr_private_t *priv)
         GF_ASSERT (sh);
         GF_ASSERT (priv);
 
+        if (sh->force_confirm_spb)
+                return _gf_true;
         return (sh->do_gfid_self_heal
                 || sh->do_missing_entry_self_heal
                 || (afr_data_self_heal_enabled (priv->data_self_heal) &&
@@ -1516,13 +1559,11 @@ afr_lookup_set_self_heal_params (afr_local_t *local, xlator_t *this)
         int32_t                 child1 = -1;
         int32_t                 child2 = -1;
         afr_self_heal_t         *sh = NULL;
-        gf_boolean_t            split_brain = _gf_false;
 
         priv  = this->private;
         sh = &local->self_heal;
 
-        split_brain = afr_is_split_brain (this, local->cont.lookup.inode);
-        afr_detect_self_heal_by_lookup_status (local, this, split_brain);
+        afr_detect_self_heal_by_lookup_status (local, this);
 
         if (afr_lookup_gfid_missing_count (local, this))
                 local->self_heal.do_gfid_self_heal    = _gf_true;
@@ -1549,9 +1590,11 @@ afr_lookup_set_self_heal_params (afr_local_t *local, xlator_t *this)
                 afr_lookup_set_self_heal_params_by_xattr (local, this,
                                                           xattr[child1]);
         }
-        if (afr_open_only_data_self_heal (priv->data_self_heal)
-            && !split_brain)
+        if (afr_open_only_data_self_heal (priv->data_self_heal))
                 sh->do_data_self_heal = _gf_false;
+        if (sh->do_metadata_self_heal)
+                afr_lookup_check_set_metadata_split_brain (local, this);
+        afr_detect_self_heal_by_split_brain_status (local, this);
 }
 
 int
@@ -2143,6 +2186,7 @@ afr_lookup_cont_init (afr_local_t *local, unsigned int child_count)
         struct iatt       *iatts         = NULL;
         int32_t           *success_children = NULL;
         int32_t           *sources       = NULL;
+        int32_t           **pending_matrix = NULL;
 
         GF_ASSERT (local);
         local->cont.lookup.xattrs = GF_CALLOC (child_count,
@@ -2175,6 +2219,11 @@ afr_lookup_cont_init (afr_local_t *local, unsigned int child_count)
                 goto out;
         local->cont.lookup.sources = sources;
 
+        pending_matrix = afr_matrix_create (child_count, child_count);
+        if (NULL == pending_matrix)
+                goto out;
+        local->cont.lookup.pending_matrix = pending_matrix;
+
         ret = 0;
 out:
         return ret;
diff --git a/xlators/cluster/afr/src/afr-self-heal-common.c b/xlators/cluster/afr/src/afr-self-heal-common.c
index f082685e207..48fa31d8689 100644
--- a/xlators/cluster/afr/src/afr-self-heal-common.c
+++ b/xlators/cluster/afr/src/afr-self-heal-common.c
@@ -2095,6 +2095,7 @@ afr_local_t *afr_local_copy (afr_local_t *l, xlator_t *this)
         shc->do_data_self_heal = sh->do_data_self_heal;
         shc->do_metadata_self_heal = sh->do_metadata_self_heal;
         shc->do_entry_self_heal = sh->do_entry_self_heal;
+        shc->force_confirm_spb = sh->force_confirm_spb;
         shc->forced_merge = sh->forced_merge;
         shc->background = sh->background;
         shc->type = sh->type;
@@ -2162,7 +2163,7 @@ afr_self_heal_completion_cbk (call_frame_t *bgsh_frame, xlator_t *this)
         local = bgsh_frame->local;
         sh    = &local->self_heal;
 
-        if (local->govinda_gOvinda)
+        if (local->govinda_gOvinda || sh->mdata_spb || sh->data_spb)
                 split_brain = _gf_true;
 
         afr_set_split_brain (this, sh->inode, split_brain);
diff --git a/xlators/cluster/afr/src/afr-self-heal-data.c b/xlators/cluster/afr/src/afr-self-heal-data.c
index 1672b4f282e..6619c1353c7 100644
--- a/xlators/cluster/afr/src/afr-self-heal-data.c
+++ b/xlators/cluster/afr/src/afr-self-heal-data.c
@@ -688,16 +688,6 @@ afr_sh_data_fxattrop_fstat_done (call_frame_t *frame, xlator_t *this)
         nsources = afr_build_sources (this, sh->xattr, sh->buf, sh->pending_matrix,
                                       sh->sources, sh->success_children,
                                       AFR_DATA_TRANSACTION, NULL, _gf_true);
-        if ((nsources == 0) && !sh->sync_done) {
-                gf_log (this->name, GF_LOG_DEBUG,
-                        "No self-heal needed for %s",
-                        local->loc.path);
-
-                local->govinda_gOvinda = 0;
-                afr_sh_data_finish (frame, this);
-                return 0;
-        }
-
         if ((nsources == -1)
             && (priv->favorite_child != -1)
             && (sh->child_errno[priv->favorite_child] == 0)) {
@@ -720,12 +710,12 @@ afr_sh_data_fxattrop_fstat_done (call_frame_t *frame, xlator_t *this)
                         "split-brain). Please delete the file from all but "
                         "the preferred subvolume.", local->loc.path);
 
-                local->govinda_gOvinda = 1;
+                sh->data_spb = _gf_true;
                 afr_sh_data_fail (frame, this);
                 return 0;
         }
 
-        local->govinda_gOvinda = 0;
+        sh->data_spb = _gf_false;
         ret = afr_sh_inode_set_read_ctx (sh, this);
         if (ret) {
                 gf_log (this->name, GF_LOG_DEBUG,
@@ -738,7 +728,20 @@ afr_sh_data_fxattrop_fstat_done (call_frame_t *frame, xlator_t *this)
         if (sh->sync_done) {
                 afr_sh_data_setattr (frame, this);
         } else {
-                afr_sh_data_fix (frame, this);
+                if (nsources == 0) {
+                        gf_log (this->name, GF_LOG_DEBUG,
+                                "No self-heal needed for %s",
+                                local->loc.path);
+
+                        afr_sh_data_finish (frame, this);
+                        return 0;
+                }
+
+                if (sh->do_data_self_heal &&
+                    afr_data_self_heal_enabled (priv->data_self_heal))
+                        afr_sh_data_fix (frame, this);
+                else
+                        afr_sh_data_finish (frame, this);
         }
         return 0;
 }
@@ -764,11 +767,7 @@ afr_lookup_select_read_child_by_txn_type (xlator_t *this, afr_local_t *local,
         bufs = local->cont.lookup.bufs;
         success_children = local->cont.lookup.success_children;
 
-        pending_matrix = afr_matrix_create (priv->child_count,
-                                            priv->child_count);
-        if (NULL == pending_matrix)
-                goto out;
-
+        pending_matrix = local->cont.lookup.pending_matrix;
         sources = local->cont.lookup.sources;
         memset (sources, 0, sizeof (*sources) * priv->child_count);
 
@@ -780,9 +779,7 @@ afr_lookup_select_read_child_by_txn_type (xlator_t *this, afr_local_t *local,
                         local->loc.path);
                 switch (txn_type) {
                 case AFR_DATA_TRANSACTION:
-                        afr_set_split_brain (this,
-                                             local->cont.lookup.inode,
-                                             _gf_true);
+                        local->cont.lookup.possible_spb = _gf_true;
                         nsources = 1;
                         sources[success_children[0]] = 1;
                         break;
@@ -809,7 +806,6 @@ afr_lookup_select_read_child_by_txn_type (xlator_t *this, afr_local_t *local,
                                                         sources,
                                                         priv->hash_mode, gfid);
 out:
-        afr_matrix_cleanup (pending_matrix, priv->child_count);
         gf_log (this->name, GF_LOG_DEBUG, "returning read_child: %d",
                 read_child);
         return read_child;
@@ -1351,6 +1347,17 @@ afr_sh_non_reg_lock_success (call_frame_t *frame, xlator_t *this)
         return 0;
 }
 
+gf_boolean_t
+afr_can_start_data_self_heal (afr_self_heal_t *sh, afr_private_t *priv)
+{
+        if (sh->force_confirm_spb)
+                return _gf_true;
+        if (sh->do_data_self_heal &&
+            afr_data_self_heal_enabled (priv->data_self_heal))
+                return _gf_true;
+        return _gf_false;
+}
+
 int
 afr_self_heal_data (call_frame_t *frame, xlator_t *this)
 {
@@ -1361,10 +1368,14 @@ afr_self_heal_data (call_frame_t *frame, xlator_t *this)
         local = frame->local;
         sh = &local->self_heal;
 
-        local->govinda_gOvinda = afr_is_split_brain (this, sh->inode);
-
-        if (sh->do_data_self_heal &&
-            afr_data_self_heal_enabled (priv->data_self_heal)) {
+        /* Self-heal completion cbk changes inode split-brain status based on
+         * govinda_gOvinda, mdata_spb, data_spb value.
+         * Initialize data_spb with current split-brain status.
+         * If for some reason self-heal fails(locking phase etc), it makes sure
+         * we retain the split-brain status before this self-heal started.
+         */
+        sh->data_spb = afr_is_split_brain (this, sh->inode);
+        if (afr_can_start_data_self_heal (sh, priv)) {
                 if (IA_ISREG (sh->type)) {
                         afr_sh_data_open (frame, this);
                 } else {
diff --git a/xlators/cluster/afr/src/afr-self-heal-metadata.c b/xlators/cluster/afr/src/afr-self-heal-metadata.c
index 147ab98d409..79ce07d0039 100644
--- a/xlators/cluster/afr/src/afr-self-heal-metadata.c
+++ b/xlators/cluster/afr/src/afr-self-heal-metadata.c
@@ -50,7 +50,7 @@ afr_sh_metadata_done (call_frame_t *frame, xlator_t *this)
         sh = &local->self_heal;
 
         afr_sh_reset (frame, this);
-        if (local->govinda_gOvinda) {
+        if (sh->mdata_spb) {
                 gf_log (this->name, GF_LOG_INFO,
                         "split-brain detected, aborting selfheal of %s",
                         local->loc.path);
@@ -383,15 +383,6 @@ afr_sh_metadata_fix (call_frame_t *frame, xlator_t *this,
                                       sh->pending_matrix, sh->sources,
                                       sh->success_children,
                                       AFR_METADATA_TRANSACTION, NULL, _gf_false);
-        if (nsources == 0) {
-                gf_log (this->name, GF_LOG_TRACE,
-                        "No self-heal needed for %s",
-                        local->loc.path);
-
-                afr_sh_metadata_finish (frame, this);
-                goto out;
-        }
-
         if ((nsources == -1)
             && (priv->favorite_child != -1)
             && (sh->child_errno[priv->favorite_child] == 0)) {
@@ -413,7 +404,17 @@ afr_sh_metadata_fix (call_frame_t *frame, xlator_t *this,
                         "(possible split-brain). Please fix the file on "
                         "all backend volumes", local->loc.path);
 
-                local->govinda_gOvinda = 1;
+                sh->mdata_spb = _gf_true;
+
+                afr_sh_metadata_finish (frame, this);
+                goto out;
+        }
+
+        sh->mdata_spb = _gf_false;
+        if (nsources == 0) {
+                gf_log (this->name, GF_LOG_TRACE,
+                        "No self-heal needed for %s",
+                        local->loc.path);
 
                 afr_sh_metadata_finish (frame, this);
                 goto out;
@@ -452,7 +453,10 @@ afr_sh_metadata_fix (call_frame_t *frame, xlator_t *this,
                                         sh->fresh_children);
         }
 
-        afr_sh_metadata_sync_prepare (frame, this);
+        if (sh->do_metadata_self_heal && priv->metadata_self_heal)
+                afr_sh_metadata_sync_prepare (frame, this);
+        else
+                afr_sh_metadata_finish (frame, this);
 out:
         return;
 }
@@ -512,17 +516,35 @@ afr_sh_metadata_lock (call_frame_t *frame, xlator_t *this)
         return 0;
 }
 
+gf_boolean_t
+afr_can_start_metadata_self_heal (afr_self_heal_t *sh, afr_private_t *priv)
+{
+        if (sh->force_confirm_spb)
+                return _gf_true;
+        if (sh->do_metadata_self_heal && priv->metadata_self_heal)
+                return _gf_true;
+        return _gf_false;
+}
 
 int
 afr_self_heal_metadata (call_frame_t *frame, xlator_t *this)
 {
         afr_local_t   *local = NULL;
         afr_private_t *priv = this->private;
-
+        afr_self_heal_t *sh = &local->self_heal;
 
         local = frame->local;
+        sh = &local->self_heal;
+
+        /* Self-heal completion cbk changes inode split-brain status based on
+         * govinda_gOvinda, mdata_spb, data_spb value.
+         * Initialize mdata_spb with current split-brain status.
+         * If for some reason self-heal fails(locking phase etc), it makes sure
+         * we retain the split-brain status before this self-heal started.
+         */
+        sh->mdata_spb = afr_is_split_brain (this, sh->inode);
 
-        if (local->self_heal.do_metadata_self_heal && priv->metadata_self_heal) {
+        if (afr_can_start_metadata_self_heal (sh, priv)) {
                 afr_sh_metadata_lock (frame, this);
         } else {
                 afr_sh_metadata_done (frame, this);
diff --git a/xlators/cluster/afr/src/afr.h b/xlators/cluster/afr/src/afr.h
index abb95533449..5ed478c4a2f 100644
--- a/xlators/cluster/afr/src/afr.h
+++ b/xlators/cluster/afr/src/afr.h
@@ -170,6 +170,8 @@ typedef struct {
         gf_boolean_t do_entry_self_heal;
         gf_boolean_t do_gfid_self_heal;
         gf_boolean_t do_missing_entry_self_heal;
+        gf_boolean_t force_confirm_spb; /* Check for split-brains even when
+                                           self-heal is turned off */
 
         gf_boolean_t forced_merge;        /* Is this a self-heal triggered to
                                              forcibly merge the directories? */
@@ -266,6 +268,8 @@ typedef struct {
         int (*algo_completion_cbk) (call_frame_t *frame, xlator_t *this);
         int (*algo_abort_cbk) (call_frame_t *frame, xlator_t *this);
         void (*gfid_sh_success_cbk) (call_frame_t *sh_frame, xlator_t *this);
+        gf_boolean_t    mdata_spb;
+        gf_boolean_t    data_spb;
 
         call_frame_t *sh_frame;
 } afr_self_heal_t;
@@ -444,7 +448,9 @@ typedef struct _afr_local {
                         int32_t read_child;
                         int32_t *sources;
                         int32_t *success_children;
+                        int32_t **pending_matrix;
                         gf_boolean_t fresh_lookup;
+                        gf_boolean_t possible_spb;
                 } lookup;
 
                 struct {