On Fri, Apr 19, 2013 at 07:13:10AM +0800, Zheng Liu wrote:
> [Sorry, it seems that I got a delivery error. So send again]
>
> On 04/19/2013 05:58 AM, Theodore Ts'o wrote:
> > It looks like there is absolutely no support for metadata checksums in
> > fs/ext4/move_extent.c. So if you try to defrag a file on a
> > metadata_csum, it leaves the file system corrupted.
> >
> > We really, really should get this fixed ASAP, but until we do, let's
> > disable e4defrag on metadata_csum file systems so we avoid corrupting
> > file systems.
> >
> > Cc: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
> > Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
>
> Yes, I also notice this problem. So currently it seems that the best
> choice is to disable defrag for metadata_csum.
I think this happens because mext_insert_extents() open-codes the metadata
dirtying and forgets to update the extent block header. It should call
ext4_ext_dirty() at the end, instead. :(
I should see if there are any other sites that dirty metadata without making
the proper csum_set calls. Will send a fix shortly, so NAK.
--D
>
> Reviewed-By: Zheng Liu <wenqing.lz@xxxxxxxxxx>
>
> Thanks,
> - Zheng
>
> > ---
> > fs/ext4/ioctl.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> > index 9491ac0..2d043da 100644
> > --- a/fs/ext4/ioctl.c
> > +++ b/fs/ext4/ioctl.c
> > @@ -450,6 +450,15 @@ group_extend_out:
> > goto mext_out;
> > }
> >
> > + if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
> > + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
> > + ext4_msg(sb, KERN_ERR,
> > + "Online defrag not supported with "
> > + "metadata_csum");
> > + err = -EOPNOTSUPP;
> > + goto mext_out;
> > + }
> > +
> > err = mnt_want_write_file(filp);
> > if (err)
> > goto mext_out;
> >
>
> --
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