[PATCH v17 05/21] fsverity: don't allow setting DAX file attribute on fsverity files

[Andrey Albershteyn <aalbersh@kernel.org>]

When fsverity is enabled on the file, with FS_IOC_ENABLE_VERITY ioctl(),
it checks if file has DAX enabled and fails if that's true. However, the
opposite case is not checked.

Note, that the only other filesystem supporting DAX and fsverity is
ext4, and ext4 does check for this case.

Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
---
 fs/file_attr.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/file_attr.c b/fs/file_attr.c
index bfb00d256dd5..391edd1d0ce3 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -235,10 +235,15 @@ static int fileattr_set_prepare(struct inode *inode,
 	/*
 	 * It is only valid to set the DAX flag on regular files and
 	 * directories on filesystems.
+	 *
+	 * DAX and fsverity are incompatible.
 	 */
-	if ((fa->fsx_xflags & FS_XFLAG_DAX) &&
-	    !(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
-		return -EINVAL;
+	if (fa->fsx_xflags & FS_XFLAG_DAX) {
+		if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
+			return -EINVAL;
+		if (old_ma->fsx_xflags & FS_XFLAG_VERITY)
+			return -EINVAL;
+	}
 
 	/* Extent size hints of zero turn off the flags. */
 	if (fa->fsx_extsize == 0)
-- 
2.54.0