xfs: allow setting file attributes on special files

XFS does't have file attributes manipulation ioctls for special
files. Changing or reading file attributes is rejected for them in
xfs_fileattr_*et().

In XFS, this is necessary to work for project quota directories.
When project is set up, xfs_quota opens and calls FS_IOC_SETFSXATTR on
every inode in the directory. However, special files are skipped due to
open() returning a special inode for them. So, they don't even get to
this check.

The recently added file_getattr/file_setattr will call xfs_fileattr_*et,
on special files. This patch allows reading/changing file attributes on
special files.

Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

fs/xfs/xfs_ioctl.c

@@ -512,9 +512,6 @@ xfs_fileattr_get(
 {
 	struct xfs_inode	*ip = XFS_I(d_inode(dentry));
 
-	if (d_is_special(dentry))
-		return -ENOTTY;
-
 	xfs_ilock(ip, XFS_ILOCK_SHARED);
 	xfs_fill_fsxattr(ip, XFS_DATA_FORK, fa);
 	xfs_iunlock(ip, XFS_ILOCK_SHARED);
@@ -736,9 +733,6 @@ xfs_fileattr_set(
 
 	trace_xfs_ioctl_setattr(ip);
 
-	if (d_is_special(dentry))
-		return -ENOTTY;
-
 	if (!fa->fsx_valid) {
 		if (fa->flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL |
 				  FS_NOATIME_FL | FS_NODUMP_FL |