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: Jan Kara <jack@xxxxxxx> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx> 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> --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 11b9909c91df..edbf988de86c 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -798,7 +798,7 @@ 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
