From c3ca015fab6df124c933b91902f3f2a3473f9da5 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Thu, 31 Aug 2017 21:47:43 -0400 Subject: dax: remove the pmem_dax_ops->flush abstraction Commit abebfbe2f731 ("dm: add ->flush() dax operation support") is buggy. A DM device may be composed of multiple underlying devices and all of them need to be flushed. That commit just routes the flush request to the first device and ignores the other devices. It could be fixed by adding more complex logic to the device mapper. But there is only one implementation of the method pmem_dax_ops->flush - that is pmem_dax_flush() - and it calls arch_wb_cache_pmem(). Consequently, we don't need the pmem_dax_ops->flush abstraction at all, we can call arch_wb_cache_pmem() directly from dax_flush() because dax_dev->ops->flush can't ever reach anything different from arch_wb_cache_pmem(). It should be also pointed out that for some uses of persistent memory it is needed to flush only a very small amount of data (such as 1 cacheline), and it would be overkill if we go through that device mapper machinery for a single flushed cache line. Fix this by removing the pmem_dax_ops->flush abstraction and call arch_wb_cache_pmem() directly from dax_flush(). Also, remove the device mapper code that forwards the flushes. Fixes: abebfbe2f731 ("dm: add ->flush() dax operation support") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka Reviewed-by: Dan Williams Signed-off-by: Mike Snitzer --- fs/dax.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/dax.c b/fs/dax.c index 865d42c63e23..18d970fb0e09 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -783,7 +783,7 @@ static int dax_writeback_one(struct block_device *bdev, } dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(pfn)); - dax_flush(dax_dev, pgoff, kaddr, size); + dax_flush(dax_dev, 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 @@ -978,7 +978,7 @@ int __dax_zero_page_range(struct block_device *bdev, return rc; } memset(kaddr + offset, 0, size); - dax_flush(dax_dev, pgoff, kaddr + offset, size); + dax_flush(dax_dev, kaddr + offset, size); dax_read_unlock(id); } return 0; -- cgit v1.2.3-58-ga151