On Wed 14-06-17 16:11:26, Dan Williams wrote:
> Some platforms arrange for cpu caches to be flushed on power-fail. On
> those platforms there is no requirement that the kernel track and flush
> potentially dirty cache lines. Given that we still insert entries into
> the radix for locking purposes this patch only disables the cache flush
> loop, not the dirty tracking.
>
> Userspace can override the default cache setting via the block device
> queue "write_cache" attribute in sysfs.
>
> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> Suggested-by: Jan Kara <jack@xxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> Changes since v3:
> * move the check of QUEUE_FLAG_WC into the pmem driver directly (Jan)
>
> drivers/nvdimm/pmem.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index 06f6c27ec1e9..49938b246a7b 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -244,7 +244,16 @@ static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
> static void pmem_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff,
> void *addr, size_t size)
> {
> - arch_wb_cache_pmem(addr, size);
> + struct pmem_device *pmem = dax_get_private(dax_dev);
> + struct gendisk *disk = pmem->disk;
> + struct request_queue *q = disk->queue;
> +
> + /*
> + * Only perform cache management when the queue has caching
> + * enabled.
> + */
> + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
> + arch_wb_cache_pmem(addr, size);
> }
>
> static const struct dax_operations pmem_dax_ops = {
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
