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

[Peter Lieven <pl@kamp.de>]

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 <pl@kamp.de>
>>>> ---
>>>>    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