On Monday 11 February 2008, Sergei Shtylyov wrote:
> Bartlomiej Zolnierkiewicz wrote:
>
> > From: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
> > Subject: [PATCH] ide-disk: fix flush requests (take 2)
>
> > commit 813a0eb233ee67d7166241a8b389b6a76f2247f9
> > Author: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
> > Date: Fri Jan 25 22:17:10 2008 +0100
>
> > ide: switch idedisk_prepare_flush() to use REQ_TYPE_ATA_TASKFILE requests
>
> > ...
>
> > broke flush requests.
>
> > Allocating IDE command structure on the stack for flush requests is not
> > a very brilliant idea:
>
> > - idedisk_prepare_flush() only prepares the request and it doesn't wait
> > for it to be completed
>
> > - there are can be multiple flush requests queued in the queue
>
> > Fix the problem (per hints from James Bottomley) by:
> > - dynamically allocating ide_task_t instance using kmalloc(..., GFP_ATOMIC)
> > - adding new taskfile flag (IDE_TFLAG_DYN)
> > - calling kfree() in ide_end_drive_command() if IDE_TFLAG_DYN is set
> > (while at it rename 'args' to 'task' and fix whitespace damage)
>
> > [ This will be fixed properly before 2.6.25 but this bug is rather
> > critical and the proper solution requires some more work + testing. ]
>
> > Thanks to Sebastian Siewior and Christoph Hellwig for reporitng the
> > problem and testing patches (extra thanks to Sebastian for bisecting
> > it to the guilty commmit).
> >
> > Cc: Sebastian Siewior <ide-bug@xxxxxxxxxxxxxxxx>
> > Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> > Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> > Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
> > Cc: Tejun Heo <htejun@xxxxxxxxx>
> > Cc: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
> > Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
>
> Acked-by: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
>
> > Index: b/drivers/ide/ide-disk.c
> > ===================================================================
> > --- a/drivers/ide/ide-disk.c
> > +++ b/drivers/ide/ide-disk.c
> > @@ -590,20 +590,24 @@ static ide_proc_entry_t idedisk_proc[] =
> > static void idedisk_prepare_flush(struct request_queue *q, struct request *rq)
> > {
> > ide_drive_t *drive = q->queuedata;
> > - ide_task_t task;
> > + ide_task_t *task = kmalloc(sizeof(*task), GFP_ATOMIC);
> >
> > - memset(&task, 0, sizeof(task));
> > + /* FIXME: map struct ide_taskfile on rq->cmd[] */
> > + BUG_ON(task == NULL);
> > +
> > + memset(task, 0, sizeof(*task));
>
> Why not kzalloc() then?
Well, yes. However since the patch has been already merged upstream and it
is only a temporary solution I don't think it is worth doing it now (OTOH if
somebody sends me a patch I'll happily merge it).
Thanks,
Bart
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