[systemd-devel] [EXT] [PATCH] libblkid: fix spurious ext superblock checksum mismatches

[Windl, Ulrich]

> -----Original Message-----
> From: systemd-devel <systemd-devel-bounces at lists.freedesktop.org> On
> Behalf Of Krister Johansen
> Sent: Monday, November 18, 2024 9:35 PM
> To: util-linux at vger.kernel.org
> Cc: Karel Zak <kzak at redhat.com>; systemd-devel at lists.freedesktop.org;
> David Reaver <me at davidreaver.com>; Theodore Ts'o <tytso at mit.edu>
> Subject: [EXT] [systemd-devel] [PATCH] libblkid: fix spurious ext superblock
> checksum mismatches
> 
> Reads of ext superblocks can race with updates.  If libblkid observes a
[Windl, Ulrich] 

I really wonder:

Can one single block be inconsistent when read, considering that the block on disk is not inconsistent?
That would mean that the block buffer you are reading is being modified by another process.
AFAIK the basic UNIX semantic guarantee that a block is read atomically; if it's not, something is severely broken, and I don't think that O_DIRECT fixes that.