ecryptfs: allow lower fs to interpret ATTR_KILL_S*ID

Make sure ecryptfs doesn't trip the BUG() in notify_change.  This also allows
the lower filesystem to interpret ATTR_KILL_S*ID in its own way.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 5701f816faf4..0b1ab016fa2e 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -914,6 +914,14 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
                 if (rc < 0)
                         goto out;
         }
+
+        /*
+         * mode change is for clearing setuid/setgid bits. Allow lower fs
+         * to interpret this in its own way.
+         */
+        if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
+                ia->ia_valid &= ~ATTR_MODE;
+
         rc = notify_change(lower_dentry, ia);
 out:
         fsstack_copy_attr_all(inode, lower_inode, NULL);