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    SubjectRe: [PATCH 4/4] Btrfs: add basic DIO read/write support V3
    On Thu, 13 May 2010 14:01:37 -0400
    Josef Bacik <josef@redhat.com> wrote:

    > On Thu, May 13, 2010 at 11:26:39AM -0400, Christoph Hellwig wrote:
    > > On Thu, May 13, 2010 at 11:31:45AM -0400, Josef Bacik wrote:
    > > > AIO's aio_complete does kmap with KM_IRQ0/1 and it gets called in the same
    > > > context as the btrfs completion handler, so if it's ok for aio_complete it
    > > > should be ok for btrfs right? Thanks,
    > >
    > > aio_complete does a spin_lock_irqsave before that, which disables
    > > interrupts on the local CPU.
    > >
    >
    > Ok how about I just do
    >
    > local_irq_disable()
    > kmap(KM_IRQ0)
    > local_irq_enable()
    >
    > would that be acceptable? Thanks,

    yup.

    local_irq_disable() (or local_irq_save())
    kmap_atomic(KM_IRQx);
    <stuff>
    kunmap_atomic(KM_IRQx);
    local_irq_enable() (or local_irq_restore()).

    then perhaps flush_dcache_page().


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