filesystem-dax: convert to dax_flush()

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 the dax_flush()
helper skips cache management work when the underlying driver does not
specify a flush method.

We still do all the dirty tracking since the radix entry will already be
there for locking purposes. However, the work to clean the entry will be
a nop for some dax drivers.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.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>

diff --git a/fs/dax.c b/fs/dax.c
index b459948..0933fc4 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -784,7 +784,7 @@ static int dax_writeback_one(struct block_device *bdev,
        }
 
        dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(pfn));
-       wb_cache_pmem(kaddr, size);
+       dax_flush(dax_dev, pgoff, kaddr, size);
        /*
         * After we have flushed the cache, we can clear the dirty tag. There
         * cannot be new dirty data in the pfn after the flush has completed as