glusterd/afr: store afr pending xattrs as a volume option

Backport of http://review.gluster.org/#/c/12738/

Problem:
When AFR xlator initialises, it uses the name of the client xlators
below it for storing the pending changelogs (xattrs). This can be
problem when some other xlator is loaded in between AFR and the client.
Though that is a trivial 'traverse-graph-till-the-client-and-use-the-name'
fix in AFR's init(), there are other issues like when there's no client
xlator at all when, say, AFR is moved to the server side.

Fix:
The client xlator names are currenly unique and stored as
brickinfo->brick_ids. So persist these ids as comma separated values in
AFR's volume_options and use them as xattr values during init().

Change-Id: Ie761ffeb3373a4c4d85ad05c84a768c4188aa90d
BUG: 1291985
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-on: http://review.gluster.org/12977
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>

1 files changed, 23 insertions, 9 deletions

diff --git a/xlators/cluster/afr/src/afr.c b/xlators/cluster/afr/src/afr.c
index 5ef920a13d1..4c072b6c69f 100644
--- a/xlators/cluster/afr/src/afr.c
+++ b/xlators/cluster/afr/src/afr.c
@@ -248,6 +248,8 @@ init (xlator_t *this)
         int            read_subvol_index = -1;
         xlator_t      *fav_child   = NULL;
         char          *qtype       = NULL;
+        char          *xattrs_list = NULL;
+        char          *ptr         = NULL;
 
         if (!this->children) {
                 gf_msg (this->name, GF_LOG_ERROR, 0,
@@ -401,6 +403,7 @@ init (xlator_t *this)
                 goto out;
         }
 
+        GF_OPTION_INIT ("afr-pending-xattr", xattrs_list, str, out);
         priv->pending_key = GF_CALLOC (sizeof (*priv->pending_key),
                                        child_count,
                                        gf_afr_mt_char);
@@ -408,20 +411,25 @@ init (xlator_t *this)
                 ret = -ENOMEM;
                 goto out;
         }
-
-        trav = this->children;
-        i = 0;
-        while (i < child_count) {
-                priv->children[i] = trav->xlator;
-
+        ptr = gf_strdup (xattrs_list);
+        if (!ptr) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        for (i = 0, ptr = strtok (ptr, ","); ptr; ptr = strtok (NULL, ",")) {
                 ret = gf_asprintf (&priv->pending_key[i], "%s.%s",
-                                   AFR_XATTR_PREFIX,
-                                   trav->xlator->name);
-                if (-1 == ret) {
+                                   AFR_XATTR_PREFIX, ptr);
+                if (ret  == -1) {
                         ret = -ENOMEM;
                         goto out;
                 }
+                i++;
+        }
 
+        trav = this->children;
+        i = 0;
+        while (i < child_count) {
+                priv->children[i] = trav->xlator;
                 trav = trav->next;
                 i++;
         }
@@ -457,6 +465,7 @@ init (xlator_t *this)
 
         ret = 0;
 out:
+        GF_FREE (ptr);
         return ret;
 }
 
@@ -780,6 +789,11 @@ struct volume_options options[] = {
 	  .type = GF_OPTION_TYPE_STR,
 	  .default_value = AFR_DIRTY_DEFAULT,
 	},
+	{ .key = {"afr-pending-xattr"},
+	  .type = GF_OPTION_TYPE_STR,
+          .description = "Comma seperated list of xattrs that are used to  "
+                         "capture information on pending heals."
+	},
 	{ .key = {"metadata-splitbrain-forced-heal"},
 	  .type = GF_OPTION_TYPE_BOOL,
 	  .default_value = "off",