linux-ext4 - Re: [PATCH 4/6] Ext4: fail if we try to use hole punch

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 16 Nov 2010 22:06:40 -0500
From:	Ted Ts'o <tytso@....edu>
To:	Avi Kivity <avi@...hat.com>
Cc:	Josef Bacik <josef@...hat.com>, david@...morbit.com,
	linux-kernel@...r.kernel.org, linux-btrfs@...r.kernel.org,
	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	xfs@....sgi.com, cmm@...ibm.com, cluster-devel@...hat.com,
	ocfs2-devel@....oracle.com
Subject: Re: [PATCH 4/6] Ext4: fail if we try to use hole punch

> >There is no simple way to test if a filesystem supports hole punching or not so
> >the check has to be done per fs.  Thanks,
> 
> Could put a flag word in superblock_operations.  Filesystems which
> support punching (or other features) can enable it there.

No, it couldn't be in super_operations.  It may vary on a per-inode
basis for some file systems, such as ext4 (depending on whether the
inode is extent-mapped or indirect-block mapped).

So at least for ext4 we'd need to call into fallocate() function
anyway, once we add support.  I suppose if other file systems really
want it, we could add a flag to the super block ops structure, so they
don't have do the "do we support the punch" operation.  I can go
either way on that; although if we think the majority of file systems
are going support punch in the long-term, then it might not be worth
it to add such a flag.

						- Ted
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html