Re: [EXT] [PATCH] libblkid: fix spurious ext superblock checksum mismatches

["Windl, Ulrich" <u.windl@xxxxxx>]

> -----Original Message-----
> From: systemd-devel <systemd-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On
> Behalf Of Krister Johansen
> Sent: Monday, November 18, 2024 9:35 PM
> To: util-linux@xxxxxxxxxxxxxxx
> Cc: Karel Zak <kzak@xxxxxxxxxx>; systemd-devel@xxxxxxxxxxxxxxxxxxxxx;
> David Reaver <me@xxxxxxxxxxxxxxx>; Theodore Ts'o <tytso@xxxxxxx>
> Subject: [EXT]  [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.