On Fri 09-06-17 13:24:07, Dan Williams wrote:
> Filesystem-DAX flushes caches whenever it writes to the address returned
> through dax_direct_access() and when writing back dirty radix entries.
> That flushing is only required in the pmem case, so add a dax operation
> to allow pmem to take this extra action, but skip it for other dax
> capable devices that do not provide a flush routine.
>
> An example for this differentiation might be a volatile ram disk where
> there is no expectation of persistence. In fact the pmem driver itself might
> front such an address range specified by the NFIT. So, this "no flush"
> property might be something passed down by the bus / libnvdimm.
>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> drivers/nvdimm/pmem.c | 7 +++++++
> include/linux/dax.h | 2 ++
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index 2f3aefe565c6..823b07774244 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -242,9 +242,16 @@ static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
> return copy_from_iter_flushcache(addr, bytes, i);
> }
>
> +static void pmem_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff,
> + void *addr, size_t size)
> +{
> + wb_cache_pmem(addr, size);
> +}
> +
> static const struct dax_operations pmem_dax_ops = {
> .direct_access = pmem_dax_direct_access,
> .copy_from_iter = pmem_copy_from_iter,
> + .flush = pmem_dax_flush,
> };
>
> static void pmem_release_queue(void *q)
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 28e398f8c59e..407dd3ff6e54 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -19,6 +19,8 @@ struct dax_operations {
> /* copy_from_iter: dax-driver override for default copy_from_iter */
> size_t (*copy_from_iter)(struct dax_device *, pgoff_t, void *, size_t,
> struct iov_iter *);
> + /* flush: optional driver-specific cache management after writes */
> + void (*flush)(struct dax_device *, pgoff_t, void *, size_t);
> };
>
> #if IS_ENABLED(CONFIG_DAX)
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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