[PATCH] dax: kill uml support

[Dan Williams]

The lack of common transparent-huge-page helpers for UML is becoming
increasingly painful for fs/dax.c now that it is growing more pmd
functionality. Add UML to the list of unsupported architectures, and
clean up no-longer-necessary ifdef as a result.

Cc: Jan Kara <jack@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
 fs/Kconfig |    2 +-
 fs/dax.c   |    4 +---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/Kconfig b/fs/Kconfig
index c2a377cdda2b..661931fb0ce0 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -37,7 +37,7 @@ source "fs/f2fs/Kconfig"
 config FS_DAX
 	bool "Direct Access (DAX) support"
 	depends on MMU
-	depends on !(ARM || MIPS || SPARC)
+	depends on !(ARM || MIPS || SPARC || UML)
 	help
 	  Direct Access (DAX) can be used on memory-backed block devices.
 	  If the block device supports DAX and the filesystem supports DAX,
diff --git a/fs/dax.c b/fs/dax.c
index ddcddfeaa03b..86df835783ea 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -710,8 +710,7 @@ static void dax_mapping_entry_mkclean(struct address_space *mapping,
 		if (follow_pte_pmd(vma->vm_mm, address, &ptep, &pmdp, &ptl))
 			continue;
 
-		if (pmdp) {
-#ifdef CONFIG_FS_DAX_PMD
+		if (pmdp && IS_ENABLED(CONFIG_FS_DAX_PMD)) {
 			pmd_t pmd;
 
 			if (pfn != pmd_pfn(*pmdp))
@@ -727,7 +726,6 @@ static void dax_mapping_entry_mkclean(struct address_space *mapping,
 			changed = true;
 unlock_pmd:
 			spin_unlock(ptl);
-#endif
 		} else {
 			if (pfn != pte_pfn(*ptep))
 				goto unlock_pte;