geo-rep: Fix Permission denied traceback on non root setup

Problem:
While syncing rename of directory in hybrid crawl, geo-rep
crashes as below.

Traceback (most recent call last):
  File "/usr/local/libexec/glusterfs/python/syncdaemon/repce.py", line 118, in worker
    res = getattr(self.obj, rmeth)(*in_data[2:])
  File "/usr/local/libexec/glusterfs/python/syncdaemon/resource.py", line 588, in entry_ops
    src_entry = get_slv_dir_path(slv_host, slv_volume, gfid)
  File "/usr/local/libexec/glusterfs/python/syncdaemon/syncdutils.py", line 687, in get_slv_dir_path
    [ENOENT], [ESTALE])
  File "/usr/local/libexec/glusterfs/python/syncdaemon/syncdutils.py", line 546, in errno_wrap
    return call(*arg)
PermissionError: [Errno 13] Permission denied: '/bricks/brick1/b1/.glusterfs/8e/c0/8ec0fcd4-d50f-4a6e-b473-a7943ab66640'

Cause:
Conversion of gfid to path for a directory uses readlink on backend
.glusterfs gfid path. But this fails for non root user with
permission denied.

Fix:
Use gfid2path interface to get the path from gfid

Backport of:
 > Patch: https://review.gluster.org/23570
 > Change-Id: I9d40c713a1b32cea95144cbc0f384ada82972222
 > BUG: 1763439
 > Signed-off-by: Kotresh HR <khiremat@redhat.com>

Change-Id: I9d40c713a1b32cea95144cbc0f384ada82972222
fixes: bz#1764183
Signed-off-by: Kotresh HR <khiremat@redhat.com>

2 files changed, 28 insertions, 10 deletions

diff --git a/geo-replication/syncdaemon/gsyncd.py b/geo-replication/syncdaemon/gsyncd.py
index d3c79f5692d..83e3d267b95 100644
--- a/geo-replication/syncdaemon/gsyncd.py
+++ b/geo-replication/syncdaemon/gsyncd.py
@@ -229,7 +229,8 @@ def main():
     # Set default path for config file in that case
     # If an subcmd accepts config file then it also accepts
     # master and Slave arguments.
-    if config_file is None and hasattr(args, "config_file"):
+    if config_file is None and hasattr(args, "config_file") \
+        and args.subcmd != "slave":
         config_file = "%s/geo-replication/%s_%s_%s/gsyncd.conf" % (
             GLUSTERD_WORKDIR,
             args.master,
diff --git a/geo-replication/syncdaemon/syncdutils.py b/geo-replication/syncdaemon/syncdutils.py
index 2ee10ac09fb..9cae0095cf9 100644
--- a/geo-replication/syncdaemon/syncdutils.py
+++ b/geo-replication/syncdaemon/syncdutils.py
@@ -57,6 +57,7 @@ from hashlib import sha256 as sha256
 
 # auxiliary gfid based access prefix
 _CL_AUX_GFID_PFX = ".gfid/"
+ROOT_GFID = "00000000-0000-0000-0000-000000000001"
 GF_OP_RETRIES = 10
 
 GX_GFID_CANONICAL_LEN = 37  # canonical gfid len + '\0'
@@ -670,6 +671,7 @@ def get_slv_dir_path(slv_host, slv_volume, gfid):
     global slv_bricks
 
     dir_path = ENOENT
+    pfx = gauxpfx()
 
     if not slv_bricks:
         slv_info = Volinfo(slv_volume, slv_host, master=False)
@@ -683,15 +685,30 @@ def get_slv_dir_path(slv_host, slv_volume, gfid):
                                gfid[2:4],
                                gfid], [ENOENT], [ESTALE])
         if dir_path != ENOENT:
-            realpath = errno_wrap(os.readlink, [dir_path],
-                                  [ENOENT], [ESTALE])
-            if not isinstance(realpath, int):
-                realpath_parts = realpath.split('/')
-                pargfid = realpath_parts[-2]
-                basename = realpath_parts[-1]
-                pfx = gauxpfx()
-                dir_entry = os.path.join(pfx, pargfid, basename)
-                return dir_entry
+            try:
+                realpath = errno_wrap(os.readlink, [dir_path],
+                                      [ENOENT], [ESTALE])
+                if not isinstance(realpath, int):
+                    realpath_parts = realpath.split('/')
+                    pargfid = realpath_parts[-2]
+                    basename = realpath_parts[-1]
+                    dir_entry = os.path.join(pfx, pargfid, basename)
+                    return dir_entry
+            except OSError:
+                # .gfid/GFID
+                gfidpath = unescape_space_newline(os.path.join(pfx, gfid))
+                realpath = errno_wrap(Xattr.lgetxattr_buf,
+                      [gfidpath, 'glusterfs.gfid2path'], [ENOENT], [ESTALE])
+                if not isinstance(realpath, int):
+                    basename = os.path.basename(realpath).rstrip('\x00')
+                    dirpath = os.path.dirname(realpath)
+                    if dirpath is "/":
+                        pargfid = ROOT_GFID
+                    else:
+                        dirpath = dirpath.strip("/")
+                        pargfid = get_gfid_from_mnt(dirpath)
+                    dir_entry = os.path.join(pfx, pargfid, basename)
+                    return dir_entry
 
     return None