Implement File Attribute Support

[ryao]

We add support for lsattr and chattr. Only attributes common to both
Solaris and Linux are supported. These are 'a', 'd' and 'i'. File
attributes exclusive to Solaris are present in the ZFS code, but cannot
be accessed or modified through this method. That was the case prior to
this patch.

This commit removes the ZFS_IOC_GETFLAGS and ZFS_IOC_SETFLAGS macros in
recognition that this is not equivalent to the Solaris operation. The
resolution of issue #229 should implement something
equivalent that will permit access and modification of Solaris-specific
attributes.

This resolves a regression caused by
88c2839 that broke python's
xattr.list(). This broke Gentoo Portage's FEATURES=xattr, which depended
on this.

https://bugs.gentoo.org/show_bug.cgi?id=483516
Issue #1691

Original-patch-by: Brian Behlendorf [email protected]
Signed-off-by: Richard Yao [email protected]

[ryao]

I consider this to be a high priority fix because it affects Gentoo Portage.

https://bugs.gentoo.org/show_bug.cgi?id=483516

I have asked the Gentoo developer who encountered this problem to verify that it fixes it. I intend to fast track its inclusion into Gentoo's ZFS packaging. I plan to commit a revision to Gentoo's ZFS kernel package tomorrow that includes this unless an issue is found before then.

[behlendorf]

@ryao Is this still something you're working on?

[ryao]

@behlendorf I am trying to focus on the ZIO buffers right now. I plan to revisit this after I have my initial patches ready.

[aarcane]

I'm affected by this bug as well. Is it possible to move this to milestone 0.6.3 as is, and the enhanced version you're discussing to 0.6.4 ?

[behlendorf]

@aarcane Maybe, I'd love to get this in 0.6.3 as well but it really just comes down to how much developer time is available. We'll try.

[ryao]

@behlendorf @aarcane I have refreshed this pull request. The new patch addresses previous criticisms and passes XFS Test generic/079 on my system, which tests the immutable and append bits.

[behlendorf]

@ryao Aside from the inline comments the general approach here looks good and it passed my local testing. If you can just address the comments and refresh the patch we should be able to get it in.

[ryao]

@behlendorf The pull request has been refreshed. The changes since your review a 6 hours ago should only be to make corrections for the points you made. My system is preoccupied running ztest, so I am not at liberty to do my usual regression tests. While I do not expect there to be any regressions, I am relying on your systems to catch any mistakes with this refresh.

[behlendorf]

@ryao The updated autoconf check fails incorrectly for the older interface. Including linux/sched.h for current which is used in the is_owner_or_cap macro resolves the issue. After fixing this there was a second issue which is that the result of the macro isn't used so I've resolved that we with cast. Here's a proposed fix which works as expected under CentOS 6.5.

configure:25853: checking whether is_owner_or_cap() exists
configure:25886: cp conftest.c build && make modules -C /usr/src/kernels/2.6.32-431.11.2.1chaos.ch5.2.x86_64 EXTRA_CFLAGS=-Werror   M=/home/behlendo/src/git/zfs/build
/home/behlendo/src/git/zfs/build/conftest.c: In function ���main���:
/home/behlendo/src/git/zfs/build/conftest.c:124: error: implicit declaration of function ���current_fsuid���
cc1: warnings being treated as errors
/home/behlendo/src/git/zfs/build/conftest.c:124: error: value computed is not used
make[1]: *** [/home/behlendo/src/git/zfs/build/conftest.o] Error 1
make: *** [_module_/home/behlendo/src/git/zfs/build] Error 2

diff --git a/config/kernel-is_owner_or_cap.m4 b/config/kernel-is_owner_or_cap.m4
index 7e34c66..d7e81c0 100644
--- a/config/kernel-is_owner_or_cap.m4
+++ b/config/kernel-is_owner_or_cap.m4
@@ -18,10 +18,11 @@ AC_DEFUN([ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE], [
                AC_MSG_RESULT(no)
                AC_MSG_CHECKING([whether is_owner_or_cap() exists])
                ZFS_LINUX_TRY_COMPILE([
+                       #include <linux/sched.h>
                        #include <linux/fs.h>
                ],[
                        struct inode *ip = NULL;
-                       is_owner_or_cap(ip);
+                       (void) is_owner_or_cap(ip);
                ],[
                        AC_MSG_RESULT(yes)
                        AC_DEFINE(HAVE_IS_OWNER_OR_CAP, 1, [is_owner_or_cap() ex

[behlendorf]

@ryao Just a few more markups, can you refresh it again.

[behlendorf]

Merged as:

9d31779 Implement File Attribute Support
3b4f425 Refactor inode_owner_or_capable() autotools check

Thanks @ryao for getting this pushed over the finish line. I'm thrilled to see this support finally merged.