x86, dax: replace clear_pmem() with open coded memset + dax_ops->flush

The clear_pmem() helper simply combines a memset() plus a cache flush.
Now that the flush routine is optionally provided by the dax device
driver we can avoid unnecessary cache management on dax devices fronting
volatile memory.

With clear_pmem() gone we can follow on with a patch to make pmem cache
management completely defined within the pmem driver.

Cc: <x86@kernel.org>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 0933fc460ada..554b8e7d921c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -975,7 +975,8 @@ int __dax_zero_page_range(struct block_device *bdev,
                         dax_read_unlock(id);
                         return rc;
                 }
-                clear_pmem(kaddr + offset, size);
+                memset(kaddr + offset, 0, size);
+                dax_flush(dax_dev, pgoff, kaddr + offset, size);
                 dax_read_unlock(id);
         }
         return 0;