Re: [Qemu-devel] [PATCH 1/2] glusterfs: fix max_discard

[Denis V. Lunev]

On 02/02/15 23:40, Peter Lieven wrote:
> Am 02.02.2015 um 21:09 schrieb Denis V. Lunev:
> > qemu_gluster_co_discard calculates size to discard as follows
> >      size_t size = nb_sectors * BDRV_SECTOR_SIZE;
> >      ret = glfs_discard_async(s->fd, offset, size, &gluster_finish_aiocb, acb);
> >
> > glfs_discard_async is declared as follows:
> >    int glfs_discard_async (glfs_fd_t *fd, off_t length, size_t lent,
> >                            glfs_io_cbk fn, void *data) __THROW
> > This is problematic on i686 as sizeof(size_t) == 4.
> >
> > Set bl_max_discard to SIZE_MAX >> BDRV_SECTOR_BITS to avoid overflow
> > on i386.
> >
> > Signed-off-by: Denis V. Lunev <address@hidden>
> > CC: Kevin Wolf <address@hidden>
> > CC: Peter Lieven <address@hidden>
> > ---
> >   block/gluster.c | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> >
> > diff --git a/block/gluster.c b/block/gluster.c
> > index 1eb3a8c..8a8c153 100644
> > --- a/block/gluster.c
> > +++ b/block/gluster.c
> > @@ -622,6 +622,11 @@ out:
> >       return ret;
> >   }
> >   
> > +static void qemu_gluster_refresh_limits(BlockDriverState *bs, Error **errp)
> > +{
> > +    bs->bl.max_discard = MIN(SIZE_MAX >> BDRV_SECTOR_BITS, INT_MAX);
> > +}
> > +
> Looking at the gluster code bl.max_transfer_length should have the same limit, 
> but thats a different patch.
ha, the same applies to nbd code too.

I'll do this stuff tomorrow and also I think that some
audit in other drivers could reveal something interesting.

Den