bin/94810: fsck incorrectly reports 'file system marked clean' when lost+found fills up

[Bruce Evans]

On Tue, 21 Mar 2006, Kris Kennaway wrote:

>> Description:
>
> In cases of severe filesystem damage, fsck may fill up lost+found:
>
> [...]
> SORRY. NO SPACE IN lost+found DIRECTORY
> UNEXPECTED SOFT UPDATE INCONSISTENCY
>
>
> UNREF DIR  I=871505  OWNER=root MODE=40770
> SIZE=512 MTIME=Jan  1 09:59 1970
> RECONNECT? yes
>
> SORRY. NO SPACE IN lost+found DIRECTORY
> UNEXPECTED SOFT UPDATE INCONSISTENCY
> [...]
>
> However, when fsck eventually completes it reports
>
> ***** FILE SYSTEM MARKED CLEAN *****
> ***** FILE SYSTEM WAS MODIFIED *****
>
> In fact, all of the damage was not repaired since the extra files
> could not be reconnected to lost+found, so it is necessary to:
>
> 1) mount and clean out lost+found or move it aside
>
> 2) unmount and rerun fsck to continue recovering lost files.
>
> 3) Repeat until all files have been recovered (may take multiple
> iterations)

Steps 2 and 3 seemed to be unnecessary when I ran fsck with -y.  Then
seemed to just delete everything that couldn't be reconnected to
lost+found, and fsck's claim to have cleaned the file system seemed
to be correct because the deletions worked.

Another problem with fsck -y is that you have to use it too much because
the interactive interface for answering y/n doesn't scale to large file
systems with relatively small but absolutely large damage.  fsck -y should
only be used for disposable file systems, but even then you might want to
try to preserve 2 files without interactively answering y/n up to N*2^32
times for the ones you don't care about.

Bruce