extended attributes support

[Augie Sodora]

Hello all,

I have been trying to get GlusterFS to mirror a ZFS-FUSE (0.6.9)
filesystem across two machines and have had some difficulty with
Gluster requiring extended attributes on the underlying filesystem. I
see from the source that zfs-fuse has some degree of support for
xattrs, and I tried to reenable them by commenting out the "#if 0" and
accompanying #endif in zfs_operations.c:1861, although I don't think
it had any effect.

It's not by any means crucial for me but I think it would be fun to
test it out a little bit.

Augie

[Augie Sodora]

After trying again with cleaner builds it seems to have worked without
any complaints from zfs-fuse or gluster.

I'll run some benchmarks to see exactly how much of an effect fuse's
lack of caching of attributes has on performance.

Augie

[Emmanuel Anne]

They were disabled for now because small io operations are noticeably slower with xattrs enabled. After thinking about it I think the best solution for now is to allow to enable them from the command line.

You'll see quite some big difference with something like
dd if=/dev/zero of=image count=10000 bs=1k
because for each of 10000 operations here lsxattr is called on the image file to check if it hasn't changed !

2010/6/11 Augie Sodora <aug...@gmail.com>

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[August Sodora]

In case anybody else is interested, I have attached a patch which will enable xattrs when placed in the root of the official repository and run with "patch -p0 < enable-xattr.patch"

Augie