fs: port ->setattr() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

1 files changed, 15 insertions, 14 deletions

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 515318dfbc38..ba764205bd3a 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -627,7 +627,7 @@ xfs_vn_getattr(
 
 static int
 xfs_vn_change_ok(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct dentry		*dentry,
 	struct iattr		*iattr)
 {
@@ -639,7 +639,7 @@ xfs_vn_change_ok(
 	if (xfs_is_shutdown(mp))
 		return -EIO;
 
-	return setattr_prepare(mnt_userns, dentry, iattr);
+	return setattr_prepare(idmap, dentry, iattr);
 }
 
 /*
@@ -650,7 +650,7 @@ xfs_vn_change_ok(
  */
 static int
 xfs_setattr_nonsize(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct dentry		*dentry,
 	struct xfs_inode	*ip,
 	struct iattr		*iattr)
@@ -664,6 +664,7 @@ xfs_setattr_nonsize(
 	kgid_t			gid = GLOBAL_ROOT_GID;
 	struct xfs_dquot	*udqp = NULL, *gdqp = NULL;
 	struct xfs_dquot	*old_udqp = NULL, *old_gdqp = NULL;
+	struct user_namespace	*mnt_userns = mnt_idmap_owner(idmap);
 
 	ASSERT((mask & ATTR_SIZE) == 0);
 
@@ -730,7 +731,7 @@ xfs_setattr_nonsize(
 		old_gdqp = xfs_qm_vop_chown(tp, ip, &ip->i_gdquot, gdqp);
 	}
 
-	setattr_copy(mnt_userns, inode, iattr);
+	setattr_copy(idmap, inode, iattr);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
 	XFS_STATS_INC(mp, xs_ig_attrchg);
@@ -779,7 +780,7 @@ out_dqrele:
  */
 STATIC int
 xfs_setattr_size(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct dentry		*dentry,
 	struct xfs_inode	*ip,
 	struct iattr		*iattr)
@@ -812,7 +813,7 @@ xfs_setattr_size(
 		 * Use the regular setattr path to update the timestamps.
 		 */
 		iattr->ia_valid &= ~ATTR_SIZE;
-		return xfs_setattr_nonsize(mnt_userns, dentry, ip, iattr);
+		return xfs_setattr_nonsize(idmap, dentry, ip, iattr);
 	}
 
 	/*
@@ -956,7 +957,7 @@ xfs_setattr_size(
 	}
 
 	ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
-	setattr_copy(mnt_userns, inode, iattr);
+	setattr_copy(idmap, inode, iattr);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
 	XFS_STATS_INC(mp, xs_ig_attrchg);
@@ -977,7 +978,7 @@ out_trans_cancel:
 
 int
 xfs_vn_setattr_size(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct dentry		*dentry,
 	struct iattr		*iattr)
 {
@@ -986,15 +987,15 @@ xfs_vn_setattr_size(
 
 	trace_xfs_setattr(ip);
 
-	error = xfs_vn_change_ok(mnt_userns, dentry, iattr);
+	error = xfs_vn_change_ok(idmap, dentry, iattr);
 	if (error)
 		return error;
-	return xfs_setattr_size(mnt_userns, dentry, ip, iattr);
+	return xfs_setattr_size(idmap, dentry, ip, iattr);
 }
 
 STATIC int
 xfs_vn_setattr(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct dentry		*dentry,
 	struct iattr		*iattr)
 {
@@ -1014,14 +1015,14 @@ xfs_vn_setattr(
 			return error;
 		}
 
-		error = xfs_vn_setattr_size(mnt_userns, dentry, iattr);
+		error = xfs_vn_setattr_size(idmap, dentry, iattr);
 		xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
 	} else {
 		trace_xfs_setattr(ip);
 
-		error = xfs_vn_change_ok(mnt_userns, dentry, iattr);
+		error = xfs_vn_change_ok(idmap, dentry, iattr);
 		if (!error)
-			error = xfs_setattr_nonsize(mnt_userns, dentry, ip, iattr);
+			error = xfs_setattr_nonsize(idmap, dentry, ip, iattr);
 	}
 
 	return error;