Re: [PATCH 1/4] xfs_repair: validate & fix inode CRCs

Carlos Maiolino
2015-03-09T18:42:05Z

Looks good to me.

Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>

On Wed, Mar 04, 2015 at 02:58:06PM -0600, Eric Sandeen wrote:
> xfs_repair doesn't ever check an inode's CRC, so it never repairs
> them. If the root inode or realtime inodes have bad crcs, the
> fs won't even mount and can't be fixed (without using xfs_db).
>
> It's fairly straightforward to just test the inode CRC before
> we do any other checking or modification of the inode, once we
> get past the "verify only" phase of process_dinode_int();
> just mark it dirty if it's wrong and needs to be re-written.
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> Resend of patch from a while ago, but with CRC verification
> now earlier in the function, prior to any changes are made.
>
> diff --git a/repair/dinode.c b/repair/dinode.c
> index 5d9094b..384e2dd 100644
> --- a/repair/dinode.c
> +++ b/repair/dinode.c
> @@ -2291,6 +2291,27 @@ process_dinode_int(xfs_mount_t *mp,
> */
> ASSERT(uncertain == 0 || verify_mode != 0);
>
> + /*
> + * We'd really like to know if the CRC is bad before we
> + * go fixing anything; that way we have some hint about
> + * bit-rot vs bugs. Also, any changes will invalidate the
> + * existing CRC, so this is the only valid point to test it.
> + *
> + * Of course if we make any modifications after this, the
> + * inode gets rewritten, and CRC is updated automagically.
> + */
> + if (!verify_mode && xfs_sb_version_hascrc(&mp->m_sb)) {
> + if(!xfs_verify_cksum((char *)dino, mp->m_sb.sb_inodesize,
> + XFS_DINODE_CRC_OFF)) {
> + do_warn(_("bad CRC for inode %" PRIu64), lino);
> + if (!no_modify) {
> + do_warn(_(", will rewrite\n"));
> + *dirty = 1;
> + } else
> + do_warn(_(", would rewrite\n"));
> + }
> + }
> +
> if (be16_to_cpu(dino->di_magic) != XFS_DINODE_MAGIC) {
> retval = 1;
> if (!uncertain)
>
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

--
Carlos