Re: [PATCH 5.12 038/127] btrfs: zoned: fix parallel compressed writes

[Greg Kroah-Hartman]

On Tue, May 25, 2021 at 02:00:54PM +0200, David Sterba wrote:
> On Mon, May 24, 2021 at 05:25:55PM +0200, Greg Kroah-Hartman wrote:
> > From: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
> > 
> > commit 764c7c9a464b68f7c6a5a9ec0b923176a05e8e8f upstream.
> > 
> > When multiple processes write data to the same block group on a
> > compressed zoned filesystem, the underlying device could report I/O
> > errors and data corruption is possible.
> > 
> > This happens because on a zoned file system, compressed data writes
> > where sent to the device via a REQ_OP_WRITE instead of a
> > REQ_OP_ZONE_APPEND operation. But with REQ_OP_WRITE and parallel
> > submission it cannot be guaranteed that the data is always submitted
> > aligned to the underlying zone's write pointer.
> > 
> > The change to using REQ_OP_ZONE_APPEND instead of REQ_OP_WRITE on a
> > zoned filesystem is non intrusive on a regular file system or when
> > submitting to a conventional zone on a zoned filesystem, as it is
> > guarded by btrfs_use_zone_append.
> > 
> > Reported-by: David Sterba <dsterba@xxxxxxxx>
> > Fixes: 9d294a685fbc ("btrfs: zoned: enable to mount ZONED incompat flag")
> > CC: stable@xxxxxxxxxxxxxxx # 5.12.x: e380adfc213a13: btrfs: zoned: pass start block to btrfs_use_zone_append
> > CC: stable@xxxxxxxxxxxxxxx # 5.12.x
> > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
> > Signed-off-by: David Sterba <dsterba@xxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> 
> We found a bug in this patch, please drop it from 5.12 queue.

This one, and the previous one, now dropped.

thanks,

greg k-h