[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] block/vdi: Fix locking for parallel requests
|
From: |
Kevin Wolf |
|
Subject: |
Re: [Qemu-devel] [PATCH] block/vdi: Fix locking for parallel requests |
|
Date: |
Wed, 18 Feb 2015 13:39:38 +0100 |
|
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 17.02.2015 um 22:33 hat Max Reitz geschrieben:
> Concurrently modifying the bmap is not a good idea;
Why? I mean, the fact that this fixes something for you probably means
that there really is some piece of local state that is invalidated by
concurrent writes, but it's not obvious to me what it is.
What could obviously happen is that metadata is written before the data
is on the disk, but as we don't support backing files for VDI, this is
irrelvant. (And if it were relevant, it stil wouldn't be fixed by your
patch because the driver never flushes.)
> this patch adds a
> lock for it. See https://bugs.launchpad.net/qemu/+bug/1422307 for what
> can go wrong without.
>
> Signed-off-by: Max Reitz <address@hidden>
Kevin