Date:	Thu, 2 Jun 2011 06:49:20 +0300
From:	"Amir G." <amir73il@...rs.sourceforge.net>
To:	Dave Chinner <david@...morbit.com>
Cc:	xfs@....sgi.com, sandeen@...hat.com, linux-ext4@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, sergey57@...il.com,
	Amir Goldstein <amir73il@...rs.sf.net>
Subject: Re: [PATCH v2] xfstests: add support for ext4dev FSTYP

On Thu, Jun 2, 2011 at 6:08 AM, Dave Chinner <david@...morbit.com> wrote:
> On Thu, Jun 02, 2011 at 05:33:34AM +0300, Amir G. wrote:
>> On Thu, Jun 2, 2011 at 5:16 AM, Amir G. <amir73il@...rs.sourceforge.net> wrote:
>> > On Thu, Jun 2, 2011 at 2:28 AM, Dave Chinner <david@...morbit.com> wrote:
>> >> On Wed, Jun 01, 2011 at 03:56:52PM +0300, amir73il@...rs.sourceforge.net wrote:
>> >>> From: Amir Goldstein <amir73il@...rs.sf.net>
>> >>>
>> >>> From: Amir Goldstein <amir73il@...rs.sf.net>
>> >>>
>> >>> blkid knows to identify the ext4dev FSTYP of a partition that was
>> >>> formatted with mkfs.ext4dev.
>> >>> quota tools and various util-linux utils are also aware of ext4dev,
>> >>> so ext4dev shares the same capabilities as ext4.
>> >>>
>> >>> Signed-off-by: Amir Goldstein <amir73il@...rs.sf.net>
>> >>> Tested-by: Sergey Ivanov <sergey57@...il.com>
>> >>> ---
>> >>> ext4dev is used to test experimental ext4 code in mutual existance
>> >>> with production ext4 code on the same system.
>> >>>
>> >>> Specifically, ext4 snapshots code is available for testing as a
>> >>> stand-alone ext4dev module for Fedora 15 and Ubuntu 11.4
>> >>> (see http://next3.sf.net).
>> >>>
>> >>> v1 -> v2:
>> >>> - undo change of fsck -t $FSTYP to fsck.$FSTYP
>> >>>
>> >>>  common.defrag |    2 +-
>> >>>  common.quota  |    4 ++--
>> >>>  common.rc     |   10 +++++-----
>> >>>  3 files changed, 8 insertions(+), 8 deletions(-)
>> >>>
>> >>> diff --git a/common.defrag b/common.defrag
>> >>> index 1bcf01d..4850803 100644
>> >>> --- a/common.defrag
>> >>> +++ b/common.defrag
>> >>> @@ -26,7 +26,7 @@ _require_defrag()
>> >>>      xfs)
>> >>>          DEFRAG_PROG=/usr/sbin/xfs_fsr
>> >>>       ;;
>> >>> -    ext4)
>> >>> +    ext4|ext4dev)
>> >>>          DEFRAG_PROG=/usr/bin/e4defrag
>> >>>       ;;
>> >>>      *)
>> >>> diff --git a/common.quota b/common.quota
>> >>> index 3c87ce1..b6d5f16 100644
>> >>> --- a/common.quota
>> >>> +++ b/common.quota
>> >>> @@ -29,7 +29,7 @@ _require_quota()
>> >>>      [ -n $QUOTA_PROG ] || _notrun "Quota user tools not installed"
>> >>>
>> >>>      case $FSTYP in
>> >>> -    ext2|ext3|ext4|reiserfs)
>> >>> +    ext2|ext3|ext4|ext4dev|reiserfs)
>> >>>       if [ ! -d /proc/sys/fs/quota ]; then
>> >>>           _notrun "Installed kernel does not support quotas"
>> >>>       fi
>> >>> @@ -237,7 +237,7 @@ _check_quota_usage()
>> >>>       # Sync to get delalloc to disk
>> >>>       sync
>> >>>       VFS_QUOTA=0
>> >>> -     if [ $FSTYP = "ext2" -o $FSTYP = "ext3" -o $FSTYP = "ext4" -o $FSTYP = "reiserfs" ]; then
>> >>> +     if [ $FSTYP = "ext2" -o $FSTYP = "ext3" -o $FSTYP = "ext4" -o $FSTYP = "ext4dev" -o $FSTYP = "reiserfs" ]; then
>> >>>               VFS_QUOTA=1
>> >>>               quotaon -f -u -g $SCRATCH_MNT 2>/dev/null
>> >>>       fi
>> >>
>> >> Perhaps this should be changes to a case statement?
>> >>
>> >
>> > you're making me go to v3 in such a trivial patch, but ok, I'll do it ;-)
>> >
>>
>> I rechecked the fsck -t ext4dev vs. fsck.ext4dev.
>> fsck -t ext4dev doesn't work for me :-(
>> Sergey has a newer version of  util-linux-ng
>> see:
>>
>> amir@...ab:~/xfstests$ sudo fsck -t ext4dev -nf /dev/sda5
>> fsck from util-linux-ng 2.17.2
>> e2fsck 1.41.14 (22-Dec-2010)
>> /dev/sda5 has unsupported feature(s): FEATURE_C7 FEATURE_C8 FEATURE_R7
>> e2fsck: Get a newer version of e2fsck!
>> amir@...ab:~/xfstests$ sudo fsck.ext4dev -nf /dev/sda5
>> e2fsck 1.41.14-next3-1.0.13-7 (24-May-2011)
>> Checking snapshots: 1,done
>> Pass 1: Checking inodes, blocks, and sizes
>> Pass 2: Checking directory structure
>> Pass 3: Checking directory connectivity
>> Pass 4: Checking reference counts
>> Pass 5: Checking group summary information
>> /dev/sda5: 6596/6561792 files (3.6% non-contiguous), 1242522/26216064 blocks
>> amir@...ab:~/xfstests$
>>
>> What do you thing, Dave?
>> Should xfstests rely on a non-buggy generic fsck util,
>
> For filessytems that use the generic fsck multiplexor, yes.
>
>> or just
>> implement it's own
>> non-buggy generic fsck (invoke fsck.$FSTYP directly)
>
> In general, no. XFS is a special case in that fsck.xfs is a no-op -
> it does no checking at all and only returns values needed for init
> scripts to work correctly. xfs_repair/xfs_check are for checking the
> filesystem...
>
>> I am running a recent system (Ubuntu 11.4) and I don't thing that upgrading
>> util-linux should be a requirement for xfstests to work.
>
> We do not try to support every buggy piece of crap out there - if a
> newer version of util-linux has already fixed the problem, then use
> that and we don't need to do anything special with xfstests at all.
> If you've got bleeding edge filesystem code that requires using a
> ext4dev fstyp and a new ext4 userspace, then I think that requiring
> you to use a non-buggy util-linux is not a big deal....
>

no. not a big deal at all.

> ---
>
> Personally I think that ext4dev shouldn't be supported at all. A
> special fstyp iwhile ext4 was being developed was, IMO, a stupid
> thing to do in the first place, and I was happy when it died. It
> should not be resurrected and propagated.
>
> xfstests assumes that you are using a userspace that is current with
> the version of the filesystem the kernel supports. If you are
> running a development/special branch of ext4, then you need to be
> running a userspace that understands it completely. If all you are
> doing with the ext4dev fstyp is trying to vector to a different fsck
> program that supports a new set of feature bits, then IMO you are
> doing it all wrong.
>
> Fundamentally, the filesystem is either ext4 or it isn't. If the
> features are never going to make it into mainline ext4, then you
> need a completely different fstype and full userspace support for
> that fstype. Once you have that, you can add the fstype support to
> xfstests. However, just using a different fstyp just to set a
> certain set of feature flags is, again IMO, a pretty stupid way of
> going about this.
>

The features are going into mainline, but are not there yet.
I did not invent the ext4dev standard, which is pretty well supported
by all relevant tools, but I find it very convenient for the testing.

Especially, when I expect my testers to be running a stable
distro release (i.e. F15 or Ubuntu 11.4) and be able to install
my experimental ext4dev module and utils, without it affecting
their (most likely) root ext4/ext3 fs.


> Cheers,
>
> Dave.
>
> --
> Dave Chinner
> david@...morbit.com
>
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