[PATCH 4/9] ext4: add ext4_should_use_dax()

[Ross Zwisler]

This helper, in the spirit of ext4_should_dioread_nolock() et al., replaces
the complex conditional in ext4_set_inode_flags() and will soon be called
in multiple places.

Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
 fs/ext4/ext4_jbd2.h | 15 +++++++++++++++
 fs/ext4/inode.c     |  4 +---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 48143e3..65e2aa9 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -462,4 +462,19 @@ static inline int ext4_should_dioread_nolock(struct inode *inode)
 	return 1;
 }
 
+static inline bool ext4_should_use_dax(struct inode *inode)
+{
+	if (!test_opt(inode->i_sb, DAX))
+		return false;
+	if (!S_ISREG(inode->i_mode))
+		return false;
+	if (ext4_should_journal_data(inode))
+		return false;
+	if (ext4_has_inline_data(inode))
+		return false;
+	if (ext4_encrypted_inode(inode))
+		return false;
+	return true;
+}
+
 #endif	/* _EXT4_JBD2_H */
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c774bdc..864fb94 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4599,9 +4599,7 @@ void ext4_set_inode_flags(struct inode *inode)
 		new_fl |= S_NOATIME;
 	if (flags & EXT4_DIRSYNC_FL)
 		new_fl |= S_DIRSYNC;
-	if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode) &&
-	    !ext4_should_journal_data(inode) && !ext4_has_inline_data(inode) &&
-	    !ext4_encrypted_inode(inode))
+	if (ext4_should_use_dax(inode))
 		new_fl |= S_DAX;
 	inode_set_flags(inode, new_fl,
 			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX);
-- 
2.9.5