1 files changed, 46 insertions, 1 deletions

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 779631e8e849..1b520d07d371 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -292,6 +292,38 @@ static int ext4_ioctl_check_immutable(struct inode *inode, __u32 new_projid,
 	return 0;
 }
 
+static void ext4_dax_dontcache(struct inode *inode, unsigned int flags)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+
+	if (S_ISDIR(inode->i_mode))
+		return;
+
+	if (test_opt2(inode->i_sb, DAX_NEVER) ||
+	    test_opt(inode->i_sb, DAX_ALWAYS))
+		return;
+
+	if ((ei->i_flags ^ flags) & EXT4_DAX_FL)
+		d_mark_dontcache(inode);
+}
+
+static bool dax_compatible(struct inode *inode, unsigned int oldflags,
+			   unsigned int flags)
+{
+	if (flags & EXT4_DAX_FL) {
+		if ((oldflags & EXT4_DAX_MUT_EXCL) ||
+		     ext4_test_inode_state(inode,
+					  EXT4_STATE_VERITY_IN_PROGRESS)) {
+			return false;
+		}
+	}
+
+	if ((flags & EXT4_DAX_MUT_EXCL) && (oldflags & EXT4_DAX_FL))
+			return false;
+
+	return true;
+}
+
 static int ext4_ioctl_setflags(struct inode *inode,
 			       unsigned int flags)
 {
@@ -320,6 +352,12 @@ static int ext4_ioctl_setflags(struct inode *inode,
 		if (!capable(CAP_SYS_RESOURCE))
 			goto flags_out;
 	}
+
+	if (!dax_compatible(inode, oldflags, flags)) {
+		err = -EOPNOTSUPP;
+		goto flags_out;
+	}
+
 	if ((flags ^ oldflags) & EXT4_EXTENTS_FL)
 		migrate = 1;
 
@@ -365,6 +403,8 @@ static int ext4_ioctl_setflags(struct inode *inode,
 	if (err)
 		goto flags_err;
 
+	ext4_dax_dontcache(inode, flags);
+
 	for (i = 0, mask = 1; i < 32; i++, mask <<= 1) {
 		if (!(mask & EXT4_FL_USER_MODIFIABLE))
 			continue;
@@ -525,12 +565,15 @@ static inline __u32 ext4_iflags_to_xflags(unsigned long iflags)
 		xflags |= FS_XFLAG_NOATIME;
 	if (iflags & EXT4_PROJINHERIT_FL)
 		xflags |= FS_XFLAG_PROJINHERIT;
+	if (iflags & EXT4_DAX_FL)
+		xflags |= FS_XFLAG_DAX;
 	return xflags;
 }
 
 #define EXT4_SUPPORTED_FS_XFLAGS (FS_XFLAG_SYNC | FS_XFLAG_IMMUTABLE | \
 				  FS_XFLAG_APPEND | FS_XFLAG_NODUMP | \
-				  FS_XFLAG_NOATIME | FS_XFLAG_PROJINHERIT)
+				  FS_XFLAG_NOATIME | FS_XFLAG_PROJINHERIT | \
+				  FS_XFLAG_DAX)
 
 /* Transfer xflags flags to internal */
 static inline unsigned long ext4_xflags_to_iflags(__u32 xflags)
@@ -549,6 +592,8 @@ static inline unsigned long ext4_xflags_to_iflags(__u32 xflags)
 		iflags |= EXT4_NOATIME_FL;
 	if (xflags & FS_XFLAG_PROJINHERIT)
 		iflags |= EXT4_PROJINHERIT_FL;
+	if (xflags & FS_XFLAG_DAX)
+		iflags |= EXT4_DAX_FL;
 
 	return iflags;
 }