posix: option to handle the shared bricks for statvfs()

Currently 'storage/posix' xlator has an option called option
`export-statfs-size no`, which exports zero as values for few
fields in `struct statvfs`. In a case of backend brick shared
between multiple brick processes, the values of these variables
should be `field_value / number-of-bricks-at-node`. This way,
even the issue of 'min-free-disk' etc at different layers would
also be handled properly when the statfs() sys call is made.

Fixes #241

> Reviewed-on: https://review.gluster.org/17618
> Reviewed-by: Jeff Darcy <jeff@pl.atyp.us>
> Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
> (cherry picked from commit febf5ed4848ad705a34413353559482417c61467)

Change-Id: I2e320e1fdcc819ab9173277ef3498201432c275f
Signed-off-by: Amar Tumballi <amarts@redhat.com>
Reviewed-on: https://review.gluster.org/17903
Smoke: Gluster Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index 6ff11a2e050..f1627df688f 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -186,6 +186,32 @@ out:
         return ret;
 }
 
+/* This is going to be a O(n^2) operation as we have to pick a brick,
+   make sure it belong to this machine, and compare another brick belonging
+   to this machine (if exists), is sharing the backend */
+static void
+gd_set_shared_brick_count (glusterd_volinfo_t *volinfo)
+{
+        glusterd_brickinfo_t *brickinfo = NULL;
+        glusterd_brickinfo_t *trav = NULL;
+
+        cds_list_for_each_entry (brickinfo, &volinfo->bricks,
+                                 brick_list) {
+                if (gf_uuid_compare (brickinfo->uuid, MY_UUID))
+                        continue;
+                brickinfo->fs_share_count = 0;
+                cds_list_for_each_entry (trav, &volinfo->bricks,
+                                         brick_list) {
+                        if (!gf_uuid_compare (trav->uuid, MY_UUID) &&
+                            (trav->statfs_fsid == brickinfo->statfs_fsid)) {
+                                brickinfo->fs_share_count++;
+                        }
+                }
+        }
+
+        return;
+}
+
 int
 glusterd_volume_brick_for_each (glusterd_volinfo_t *volinfo, void *data,
                int (*fn) (glusterd_volinfo_t *, glusterd_brickinfo_t *,
@@ -195,6 +221,8 @@ glusterd_volume_brick_for_each (glusterd_volinfo_t *volinfo, void *data,
         glusterd_volinfo_t *dup_volinfo = NULL;
         int                ret          = 0;
 
+        gd_set_shared_brick_count (volinfo);
+
         if (volinfo->type != GF_CLUSTER_TYPE_TIER) {
                 ret = _brick_for_each (volinfo, NULL, data, fn);
                 if (ret)