btrfs actually stores the whole xattr name, including the prefix ondisk,
so using the generic resolver that strips off the prefix is not very
helpful.  Instead do the real ondisk xattrs manually and only use the
generic resolver for synthetic xattrs like ACLs.

(Sorry Josef for guiding you towards the wrong direction here intially)
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

The ->list handler is really not useful at all, because we always call
btrfs_xattr_generic_list anyway.  After this is done
find_btrfs_xattr_handler becomes unused, and it becomes obvious that the
temporary name buffer allocation isn't needed but we can directly copy
into the supplied buffer.

Tested with various getfattr -d calls on varying xattr lists.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

This patch makes btrfs so it will compile properly when acls are disabled.  I
tested this and it worked with CONFIG_FS_POSIX_ACL off and on.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Signed-off-by: NChris Mason <chris.mason@oracle.com>

Signed-off-by: NChris Mason <chris.mason@oracle.com>

This patch fixes compile error on kernel-2.6.22
Signed-off-by: NChris Mason <chris.mason@oracle.com>

ACLs are stored but not used for permission checks (yet)
Signed-off-by: NChris Mason <chris.mason@oracle.com>

There was a slight problem with ACL's returning EINVAL when you tried to set an
ACL.  This isn't correct, we should be returning EOPNOTSUPP, so I did a very
ugly thing and just commented everybody out and made them return EOPNOTSUPP.
This is only temporary, I'm going back to implement ACL's, but Chris wants to
push out a release so this will suffice for now.

Also Yan suggested setting reada to -1 in the delete case to enable backwards
readahead, and in the listxattr case I moved path->reada = 2; to after the if
(!path) check so we can avoid a possible null dereference.  Thank you,
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Signed-off-by: NChris Mason <chris.mason@oracle.com>