fs/nfsd: fix update of inode attrs in CB_GETATTR

Currently, we copy the mtime and ctime to the in-core inode and then
mark the inode dirty. This is fine for certain types of filesystems, but
not all. Some require a real setattr to properly change these values
(e.g. ceph or reexported NFS).

Fix this code to call notify_change() instead, which is the proper way
to effect a setattr. There is one problem though:

In this case, the client is holding a write delegation and has sent us
attributes to update our cache. We don't want to break the delegation
for this since that would defeat the purpose. Add a new ATTR_DELEG flag
that makes notify_change bypass the try_break_deleg call.

Fixes: c5967721e106 ("NFSD: handle GETATTR conflict with write delegation")
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/fs/attr.c b/fs/attr.c
index 960a310581eb..0dbf43b6555c 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -489,9 +489,17 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 	error = security_inode_setattr(idmap, dentry, attr);
 	if (error)
 		return error;
-	error = try_break_deleg(inode, delegated_inode);
-	if (error)
-		return error;
+
+	/*
+	 * If ATTR_DELEG is set, then these attributes are being set on
+	 * behalf of the holder of a write delegation. We want to avoid
+	 * breaking the delegation in this case.
+	 */
+	if (!(ia_valid & ATTR_DELEG)) {
+		error = try_break_deleg(inode, delegated_inode);
+		if (error)
+			return error;
+	}
 
 	if (inode->i_op->setattr)
 		error = inode->i_op->setattr(idmap, dentry, attr);