Re: [Qemu-devel] [PATCH 2/2] block/iscsi: handle failure on malloc of the allocationmap

[Peter Lieven]

On 25.08.2014 13:20, Paolo Bonzini wrote:
> Il 25/08/2014 13:10, Peter Lieven ha scritto:
> > On 25.08.2014 12:37, Paolo Bonzini wrote:
> > > Il 22/08/2014 11:26, Peter Lieven ha scritto:
> > > > Signed-off-by: Peter Lieven <address@hidden>
> > > > ---
> > > >    block/iscsi.c |   22 +++++++++++++++-------
> > > >    1 file changed, 15 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/block/iscsi.c b/block/iscsi.c
> > > > index ed883c3..131357c 100644
> > > > --- a/block/iscsi.c
> > > > +++ b/block/iscsi.c
> > > > @@ -325,6 +325,19 @@ static bool is_request_lun_aligned(int64_t
> > > > sector_num, int nb_sectors,
> > > >        return 1;
> > > >    }
> > > >    +static unsigned long *iscsi_allocationmap_init(IscsiLun *iscsilun)
> > > > +{
> > > > +    unsigned long *ptr;
> > > > +    ptr =
> > > > bitmap_try_new(DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks,
> > > > +                                                      iscsilun),
> > > > +                                      iscsilun->cluster_sectors));
> > > > +    if (ptr == NULL) {
> > > > +        error_report("iSCSI: could not initialize allocationmap. "
> > > > +                     "Out of memory.");
> > > > +    }
> > > > +    return ptr;
> > > > +}
> > > > +
> > > >    static void iscsi_allocationmap_set(IscsiLun *iscsilun, int64_t
> > > > sector_num,
> > > >                                        int nb_sectors)
> > > >    {
> > > > @@ -1413,9 +1426,7 @@ static int iscsi_open(BlockDriverState *bs,
> > > > QDict *options, int flags,
> > > >            iscsilun->cluster_sectors = (iscsilun->bl.opt_unmap_gran *
> > > >                                         iscsilun->block_size) >>
> > > > BDRV_SECTOR_BITS;
> > > >            if (iscsilun->lbprz && !(bs->open_flags & BDRV_O_NOCACHE)) {
> > > > -            iscsilun->allocationmap =
> > > > -                bitmap_new(DIV_ROUND_UP(bs->total_sectors,
> > > > -                                        iscsilun->cluster_sectors));
> > > > +            iscsilun->allocationmap =
> > > > iscsi_allocationmap_init(iscsilun);
> > > >            }
> > > >        }
> > > iscsi_open has an Error ** argument.  Please pass it to
> > > iscsi_allocationmap_init and use error_setg instead of error_report.
> > I could pass the Error argument and use error_report only if the pointer
> > is null.
> No, NULL means "I don't care about errors, or I don't care about precise
> error messages and will use the return value to check for errors".
>
> > > > @@ -1508,10 +1519,7 @@ static int iscsi_truncate(BlockDriverState
> > > > *bs, int64_t offset)
> > > >          if (iscsilun->allocationmap != NULL) {
> > > >            g_free(iscsilun->allocationmap);
> > > > -        iscsilun->allocationmap =
> > > > -
> > > > bitmap_new(DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks,
> > > > -                                                    iscsilun),
> > > > -                                    iscsilun->cluster_sectors));
> > > > +        iscsilun->allocationmap = iscsi_allocationmap_init(iscsilun);
> > > Here you may have to use qerror_report_err, though I guess the failure
> > > need not be fatal and you can leave the allocationmap set to NULL.
> > That was the plan. I would also not fail on iscsi_open or would you?
> Hmm, good question.  If so, the patch is correct with error_report.  I
> thought a failure in iscsi_open would be less surprising.  The question
> then is, do we need an option to disable allocationmap queries?

We have cache=none... Otherwise if allocationmap is NULL the code
can already handle it.

Peter