GNU bug report logs - #79267
cp --sparse=auto heuristic fails on a squashfs mounted drive.

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Message #33 received at 79267 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Phillip Lougher <phillip <at> squashfs.org.uk>
Cc: jallison <at> ciq.com, 79267 <at> debbugs.gnu.org
Subject: Re: bug#79267: cp --sparse=auto heuristic fails on a squashfs mounted
 drive.
Date: Sat, 23 Aug 2025 09:46:38 -0700

On 2025-08-22 19:11, Phillip Lougher wrote:
> any Squashfs SEEK_HOLE/SEEK_DATA implementation will not
> behave like other Linux filesystems, because it won't report sparseness
> at the 4K granularity that most people or programs will expect it to.

Coreutils doesn't expect 4 KiB granularity for LSEEK_DATA+LSEEK_HOLE, 
and I don't know of any programs that do expect it. I fail to see why 
squashfs should penalize the performance of core programs like 'cp' 
merely because some (which?) programs are poorly written.

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