[PATCH 4/7] dax: Unwritten extents don't set the mapped flag

[Matthew Wilcox]

Despite an unwritten extent having a defined mapping, buffer_mapped()
returns false.  We don't need to call get_block() again here, since
we know wat the disk block is that corresponds to this file offset.
---
 fs/dax.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index b130b47..59be664 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -366,7 +366,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 	if (error)
 		goto unlock_page;
 
-	if (!buffer_mapped(&bh) && !vmf->cow_page) {
+	if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
 		if (vmf->flags & FAULT_FLAG_WRITE) {
 			error = get_block(inode, block, &bh, 1);
 			count_vm_event(PGMAJFAULT);
-- 
2.1.0


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