On 01/10/2017 06:33 AM, Niels de Vos wrote:
On Tue, Jan 10, 2017 at 10:42:36AM +0000, Ankireddypalle Reddy wrote:
Neils,
Thanks a lot. Will use this for extracting GFID.
Note that this should not be the final solution for fetching the GFID.
We will add an API for this to make it easier to use and have it well
defined and stable for the future.
A 3.10 feature?
Please write it up.
Thanks
Niels
Ram
-----Original Message-----
From: Niels de Vos [mailto:ndevos@xxxxxxxxxx]
Sent: Tuesday, January 10, 2017 4:26 AM
To: Ankireddypalle Reddy
Cc: Gluster Devel (gluster-devel@xxxxxxxxxxx); integration@xxxxxxxxxxx
Subject: Re: Get GFID for a file through libgfapi
On Mon, Jan 09, 2017 at 08:58:07PM +0000, Ankireddypalle Reddy wrote:
Neils,
Thanks for pointing to the sample code. The use case is to use GFID as a unique key for maintaining indexing information about a file when it is being backed up from GlusterFS storage. Extending GFAPI to extract GFID for a file would be great.
As per the example If I need to find GFID for a path p1/p2/p3/p4 on a glusterfs volume then should I do a look up for every level?
LOOKUP (/)->LOOKUP(p1)-> LOOKUP(p2)-> LOOKUP(p3)->
LOOKUP(p4)
No, that is not required. You can use glfs_h_lookupat() with the full path. Note that glfs_h_extract_handle() just does a memcpy() of the GFID into the given (unsigned char*), the format is of 'uuid_t'.
Attached is the modified test that shows the UUID without the need for a lookup of each component of the directory (a LOOKUP will be done by gfapi if needed).
$ make CFLAGS="-lgfapi -luuid" resolve
cc -lgfapi -luuid resolve.c -o resolve
$ ./resolve storage.example.com media resolve.log
Starting libgfapi_fini
glfs_set_volfile_server : returned 0
glfs_set_logging : returned 0
glfs_init : returned 0
glfs_set_volfile_server : returned 0
glfs_set_logging : returned 0
glfs_init : returned 0
glfs_h_extract_handle : returned 0
UUID of /installation/CentOS-7-x86_64-Everything-1503-01.iso: b1b20352-c71c-4579-b678-a7a38b0e9a84
glfs_fini : returned 0
End of libgfapi_fini
$ getfattr -n glusterfs.gfid -ehex /lan/storage.example.com/media/installation/CentOS-7-x86_64-Everything-1503-01.iso
getfattr: Removing leading '/' from absolute path names
# file: lan/storage.example.com/media/installation/CentOS-7-x86_64-Everything-1503-01.iso
glusterfs.gfid=0xb1b20352c71c4579b678a7a38b0e9a84
HTH,
Niels
Thanks and Regards,
Ram
-----Original Message-----
From: Niels de Vos [mailto:ndevos@xxxxxxxxxx]
Sent: Monday, January 09, 2017 3:39 PM
To: Ankireddypalle Reddy
Cc: Gluster Devel (gluster-devel@xxxxxxxxxxx); integration@xxxxxxxxxxx
Subject: Re: Get GFID for a file through libgfapi
On Mon, Jan 09, 2017 at 05:53:03PM +0000, Ankireddypalle Reddy wrote:
Hi,
I am trying to extract the GFID for a file through libgfapi interface. When I try to extract the value of extended attribute glusterfs.gfid through libgfapi I get the errorno: 95. This works for FUSE though. Is there a way to extract the GFID for a file through libgfapi.
It seems that this is a case where FUSE handles the xatts special. The
glusterfs.gfid and glusterfs.gfid.string (VIRTUAL_GFID_XATTR_KEY and
VIRTUAL_GFID_XATTR_KEY_STR) are specifically handled in xlators/mount/fuse/src/fuse-bridge.c.
There is a way to get the GFID, but it probably is rather a cumbersome
workaround for you. The handle-API is used heavily by NFS-Ganesha
(because NFS uses filehandles more than filenames), and extracts the
GFID from the 'struct glfs_object' with glfs_h_extract_handle(). A
basic example of how to obtain and extract the handle is in
https://github.com/gluster/glusterfs/blob/master/tests/basic/gfapi/bug
1291259.c
Could you explain the need for knowing the GFID in the application? We can extend gfapi with fetching the GFID if that would help you.
Niels
PS: we have a new integration@xxxxxxxxxxx where external projects can ask gfapi related questions. The gluster-devel list tends to be a little heavy on traffic for non-Gluster developers.
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