Re: [PATCH] [RFC] block: Don't let blk_put_request leak BIOs

[Boaz Harrosh <bharrosh@panasas.com>]

Boaz Harrosh wrote:
> Boaz Harrosh wrote:
>> If a block ULD had allocated a request and mapped some memory into it,
>> using one of blk_rq_map_xxx routines, but then for some reason failed to
>> execute the request through one of the blk_execute_request routines.
>> Then the associated BIO would leak, unless ULD resorts to low-level loops
>> intimate of block internals.
>>
>> [RFC]
>>   This code will also catch situations where LLD failed to complete
>>   the request before aborting it. Such situations are a BUG. Should we
>>   use WARN_ON_ONCE() in that case. The situation above is possible and
>>   can happen normally in memory pressure situations so maybe we should
>>   devise a bit-flag that ULD denotes that the request was aborted and
>>   only WARN_ON if flag was not set.
>>
>>   I'm sending this before any-tests so people can comment on possible
>>   pitfalls.
>>
>> Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
>> ---
> 
> I've booted a Linux PC with lots of sata disks, connected an iscsi
> target, ran OSD tests. It looks like it's working which means
> request->bio is set to NULL after it is used in the regular path.
> 
> This needs to sit in Linux next and be tested for a long while.
> 
> Jens I'll be waiting for your comment and will send a proper
> patch for the block bits. We will have to time this with James
> to see when the OSD bits can be submitted after that, then TOMO's
> patch for un-exporting blk_req_append_bio can be merged. Or maybe
> it can all go in one patch through scsi?
> 
> Thanks
> Boaz

Spock to soon this patch is shit, I'll look into it

Sorry for the noise

Boaz