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    SubjectRe: [PULL REQUEST] md bug fixes and minor improvements
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    On Fri, 2008-08-01 at 10:40 -0700, Jens Axboe wrote:
    > On Fri, Aug 01 2008, Dan Williams wrote:
    > >
    > > On Fri, 2008-08-01 at 19:22 +0200, Jens Axboe wrote:
    > > > It is a bit asymmetrical, largely due to the fact that the ->unplug_fn()
    > > > itself grabs the lock. The below patch should fix it, since Neil has
    > > > added a proper queue lock to the md queues. If someone can confirm that
    > > > this fixes it, I'll queue up a patch with proper descriptions.
    > > >
    > > > > I guess Jens is gone too..
    > > >
    > > > I'm back, just been busy this week :-)
    > > >
    > > > diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
    > > > index 621a272..f19b52f 100644
    > > > --- a/drivers/md/bitmap.c
    > > > +++ b/drivers/md/bitmap.c
    > > > @@ -1234,7 +1234,9 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
    > > > case 0:
    > > > bitmap_file_set_bit(bitmap, offset);
    > > > bitmap_count_page(bitmap,offset, 1);
    > > > + spin_lock_irq(&bitmap->mddev->queue->queue_lock);
    > > > blk_plug_device(bitmap->mddev->queue);
    > > > + spin_unlock_irq(&bitmap->mddev->queue->queue_lock);
    > > > /* fall through */
    > > > case 1:
    > > > *bmc = 2;
    > > >
    > >
    > > We also need to protect the blk_plug_device call a few lines down (and
    > > an obvious compile fix).
    >
    > Old source I guess, just one blk_plug_device() in the copy I have here.
    > Just checked latest git, still just one blk_plug_device(), are you
    > diffing against -mm or something like that? Or linux-next?

    No, my mistake... I crossed my eyes and misread your patch as protecting
    blk_unplug() a few lines up, sorry.
    >
    > And queue_lock is of course a pointer, I didn't even compile the
    > thing... Thanks for the updated variant!

    I have verified that:

    mdadm --create /dev/md0 /dev/sd[bc] -n 2 -l 1 --bitmap=internal
    dd if=/dev/zero of=/dev/md0 bs=1024k count=1

    ...no longer triggers the warning with your fix.

    Regards,
    Dan



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