[PATCH v4 7/8] fuse: support changing per-file DAX flag inside guest

[Jeffle Xu <jefflexu@linux.alibaba.com>]

Fuse client can enable or disable per-file DAX inside kernel/guest by
chattr(1). Similarly the new state won't be updated until the file is
closed and reopened later.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 fs/fuse/ioctl.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index 546ea3d58fb4..a9ed53c5dbd1 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -469,8 +469,6 @@ int fuse_fileattr_set(struct user_namespace *mnt_userns,
 	if (fa->flags_valid) {
 		err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
 				      &flags, sizeof(flags));
-		if (err)
-			goto cleanup;
 	} else {
 		memset(&xfa, 0, sizeof(xfa));
 		xfa.fsx_xflags = fa->fsx_xflags;
@@ -483,6 +481,19 @@ int fuse_fileattr_set(struct user_namespace *mnt_userns,
 				      &xfa, sizeof(xfa));
 	}
 
+	if (err)
+		goto cleanup;
+
+	if (IS_ENABLED(CONFIG_FUSE_DAX)) {
+		bool newdax;
+
+		if (fa->flags_valid)
+			newdax = flags & FS_DAX_FL;
+		else
+			newdax = fa->fsx_xflags & FS_XFLAG_DAX;
+		fuse_dax_dontcache(inode, newdax);
+	}
+
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);
 
-- 
2.27.0