s390,dcssblk,dax: Add dax zero_page_range operation to dcssblk driver

Add dax operation zero_page_range for dcssblk driver.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
CC: linux-s390@vger.kernel.org
Link: https://lore.kernel.org/r/20200228163456.1587-4-vgoyal@redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 63502ca537eb801c650615a89273809fd69b3978..ab3e2898816cff78db146722f26f51afca1d1daa 100644 (file)
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -57,11 +57,26 @@ static size_t dcssblk_dax_copy_to_iter(struct dax_device *dax_dev,
        return copy_to_iter(addr, bytes, i);
 }
 
+static int dcssblk_dax_zero_page_range(struct dax_device *dax_dev,
+                                      pgoff_t pgoff, size_t nr_pages)
+{
+       long rc;
+       void *kaddr;
+
+       rc = dax_direct_access(dax_dev, pgoff, nr_pages, &kaddr, NULL);
+       if (rc < 0)
+               return rc;
+       memset(kaddr, 0, nr_pages << PAGE_SHIFT);
+       dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT);
+       return 0;
+}
+
 static const struct dax_operations dcssblk_dax_ops = {
        .direct_access = dcssblk_dax_direct_access,
        .dax_supported = generic_fsdax_supported,
        .copy_from_iter = dcssblk_dax_copy_from_iter,
        .copy_to_iter = dcssblk_dax_copy_to_iter,
+       .zero_page_range = dcssblk_dax_zero_page_range,
 };
 
 struct dcssblk_dev_info {