[Gluster-devel] trusted.glusterfs.location

[Ville Tuulos]

Hi

I finally managed to get the trusted.glusterfs.location work with 2.0.6. I 
needed to make some minor modifications to the patch bfb7af7aa316ba, which 
adds support for trusted.glusterfs.location, to make it work with the 
latest release.

For some reason, getfattr always returned a zero-length value although it 
recognized the key. I tracked down this problem to dict_set_static_ptr in 
posix.c. Changing this to dict_set_str seemed to fix the problem, combined 
with a small change in fuse-bridge.c to drop the zero byte in the end of 
the value.

A trickier issue is that the trusted.* namespace is only accessible with 
the CAP_SYS_ADMIN capability in linux. This means that ordinary users 
can't resolve locations of files as before. Also, we're using OpenVZ 
containers for virtualization and apparently not even root has the 
CAP_SYS_ADMIN capability in a virtual machine, so 
trusted.glusterfs.location can't be accessed in a container at all.

Is there some particular reason why you couldn't expose the attribute in 
the user.* namespace? I patched our gluster to use 
user.glusterfs.location, which solves both the issue with ordinary users 
and makes the attribute available to openvz containers.

Find below a patch against 2.0.6 that fixes the aforementioned issues. I'd 
appreciate if you could consider using the user.* namespace in 2.0.7. 
Also, as I mentioned in an earlier email, it'd be useful to know all 
locations of the file when cluster/replicate is in use, to let Disco and 
others utilize replicas in case that the primary copy fails.


Ville



diff --git a/xlators/mount/fuse/src/fuse-bridge.c 
b/xlators/mount/fuse/src/fuse-bridge.c
index 61fd257..011b280 100644
--- a/xlators/mount/fuse/src/fuse-bridge.c
+++ b/xlators/mount/fuse/src/fuse-bridge.c
@@ -2000,7 +2000,7 @@ fuse_xattr_cbk (call_frame_t *frame, void *cookie, 
xlator_t *this,
                         /* if callback for getxattr */
                         value_data = dict_get (dict, state->name);
                         if (value_data) {
-                                ret = value_data->len; /* Don't return 
the value for '\0' */
+                                ret = value_data->len - 1; /* Don't 
return the value for '\0' */
                                 value = value_data->data;

                                 fuse_reply_xattr_buf (state, req, value, 
ret);
diff --git a/xlators/storage/posix/src/posix.c 
b/xlators/storage/posix/src/posix.c
index c88e964..7a04cf9 100644
--- a/xlators/storage/posix/src/posix.c
+++ b/xlators/storage/posix/src/posix.c
@@ -2241,10 +2241,10 @@ posix_getxattr (call_frame_t *frame, xlator_t 
*this,
         }

        if (loc->inode && S_ISREG (loc->inode->st_mode) && name &&
-           (strcmp (name, "trusted.glusterfs.location") == 0)) {
-                ret = dict_set_static_ptr (dict,
-                                           "trusted.glusterfs.location",
-                                           priv->hostname);
+           (strcmp (name, "user.glusterfs.location") == 0)) {
+                ret = dict_set_str (dict,
+                              "user.glusterfs.location",
+                                priv->hostname);
                 if (ret < 0) {
                         gf_log (this->name, GF_LOG_WARNING,
                                 "could not set hostname (%s) in 
dictionary",