bug#22768: Crash safety

[Paul Eggert]

Antonio Diaz Diaz wrote:

> ddrescue already provides the option '-y, --synchronous' for a somewhat
> similar functionality.

OK, let's do it as --synchronous, long-only.  If the need keeps growing we can 
add -y.

> Just now my preference is to make the behavior optional

On second thought, as Bob Proulx suggested, this is a better approach.  I tried 
the a synchronous gzip on a contrived example (compressing 1000 empty files on 
an ext4 file system on an actual hard drive with options relatime, seclabel, 
data=ordered) and synchronizing made gzip 700x slower.  Most people will prefer 
the old behavior, where gzip is faster and is unsafe mostly just in theory.

I'm attaching the patches I installed recently in this area, to help fix this 
problem.  I'll follow up on your other recent email in another message soon.

0001-gzip-fdatasync-output-dir-before-unlinking.patch
Description: Text Data

0002-gzip-use-constants-not-fileno.patch
Description: Text Data

0003-gzip-new-option-synchronous.patch
Description: Text Data

0004-misc-update-version-copyright.patch
Description: Text Data