[RFC 10/11] xfs, ext2: call dax_pfn_mkwrite() on write fault

[Ross Zwisler <ross.zwisler@linux.intel.com>]

Previously the functionality offered by dax_pfn_mkwrite() was open-coded in
XFS and ext2.  With the addition of DAX msync/fsync support we need to call
dax_pfn_mkwrite() so that the newly writeable page can be added to the
radix tree and marked as dirty.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/ext2/file.c    | 4 +++-
 fs/xfs/xfs_file.c | 9 +++++----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index fc1418c..5741e29 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -102,8 +102,8 @@ static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
 {
 	struct inode *inode = file_inode(vma->vm_file);
 	struct ext2_inode_info *ei = EXT2_I(inode);
-	int ret = VM_FAULT_NOPAGE;
 	loff_t size;
+	int ret;
 
 	sb_start_pagefault(inode->i_sb);
 	file_update_time(vma->vm_file);
@@ -113,6 +113,8 @@ static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
 	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	if (vmf->pgoff >= size)
 		ret = VM_FAULT_SIGBUS;
+	else
+		ret = dax_pfn_mkwrite(vma, vmf);
 
 	up_read(&ei->dax_sem);
 	sb_end_pagefault(inode->i_sb);
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index f429662..584e4eb 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1575,9 +1575,8 @@ xfs_filemap_pmd_fault(
 /*
  * pfn_mkwrite was originally inteneded to ensure we capture time stamp
  * updates on write faults. In reality, it's need to serialise against
- * truncate similar to page_mkwrite. Hence we open-code dax_pfn_mkwrite()
- * here and cycle the XFS_MMAPLOCK_SHARED to ensure we serialise the fault
- * barrier in place.
+ * truncate similar to page_mkwrite. Hence we cycle the XFS_MMAPLOCK_SHARED
+ * to ensure we serialise the fault barrier in place.
  */
 static int
 xfs_filemap_pfn_mkwrite(
@@ -1587,7 +1586,7 @@ xfs_filemap_pfn_mkwrite(
 
 	struct inode		*inode = file_inode(vma->vm_file);
 	struct xfs_inode	*ip = XFS_I(inode);
-	int			ret = VM_FAULT_NOPAGE;
+	int			ret;
 	loff_t			size;
 
 	trace_xfs_filemap_pfn_mkwrite(ip);
@@ -1600,6 +1599,8 @@ xfs_filemap_pfn_mkwrite(
 	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	if (vmf->pgoff >= size)
 		ret = VM_FAULT_SIGBUS;
+	else
+		ret = dax_pfn_mkwrite(vma, vmf);
 	xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
 	sb_end_pagefault(inode->i_sb);
 	return ret;
-- 
2.1.0