fuse: add "resolve-gids" mount option to overcome 32-groups limit

Add a --resolve-gids commandline option to the glusterfs binary. This
option gets set when executing "mount -t glusterfs -o resolve-gids ...".

This option is most useful in combination with the "acl" mount option.
POSIX ACL permission checking is done on the FUSE-client side to improve
performance (in addition to the checking on the bricks).

The fuse-bridge reads /proc/$PID/status by default, and this file
contains maximum 32 groups. Any local (client-side) permission checking
that requires more than the first 32 groups will fail.

By enabling the "resolve-gids" option, the fuse-bridge will call
getgrouplist() to retrieve all the groups from the user accessing the
mountpoint. This is comparable to how "nfs.server-aux-gids" works.

Note that when a user belongs to more than ~93 groups, the volume option
server.manage-gids needs to be enabled too. Without this option, the
RPC-layer will need to reduce the number of groups to make them fit in
the RPC-header.

Cherry picked from commit 64a5bf3749c67fcc00773a2716d0c7b61b0b4417:
> Change-Id: I7ede90d0e41bcf55755cced5747fa0fb1699edb2
> BUG: 1246275
> Signed-off-by: Niels de Vos <ndevos@redhat.com>
> Reviewed-on: http://review.gluster.org/11732
> Tested-by: NetBSD Build System <jenkins@build.gluster.org>
> Reviewed-by: Ravishankar N <ravishankar@redhat.com>
> Tested-by: Gluster Build System <jenkins@build.gluster.com>
> Reviewed-by: jiffin tony Thottan <jthottan@redhat.com>
> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

Change-Id: I7ede90d0e41bcf55755cced5747fa0fb1699edb2
BUG: 1246397
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/11875
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/xlators/mount/fuse/utils/mount.glusterfs.in b/xlators/mount/fuse/utils/mount.glusterfs.in
index 82660328363..112dc0a225b 100755
--- a/xlators/mount/fuse/utils/mount.glusterfs.in
+++ b/xlators/mount/fuse/utils/mount.glusterfs.in
@@ -177,6 +177,10 @@ start_glusterfs ()
         cmd_line=$(echo "$cmd_line --aux-gfid-mount");
     fi
 
+    if [ -n "$resolve_gids" ]; then
+        cmd_line=$(echo "$cmd_line --resolve-gids");
+    fi
+
     if [ -n "$no_root_squash" ]; then
         cmd_line=$(echo "$cmd_line --no-root-squash");
     fi
@@ -501,6 +505,9 @@ without_options()
                 aux_gfid_mount=1
             fi
             ;;
+        "resolve-gids")
+            resolve_gids=1
+            ;;
          # "mount -t glusterfs" sends this, but it's useless.
         "rw")
             ;;