[PATCH] add a FMODE flag to make XFS invisible I/O less hacky

[Christoph Hellwig <hch@lst.de>]

XFS has a mode called invisble I/O that doesn't update any of the
timestamps.  It's used for HSM-style applications and exposed through
the nasty open by handle ioctl.

Instead of doing directly assignment of file operations that set an
internal flag for it add a new FMODE_INVISIBLE flag that we can check
in the normal file operations.


Signed-off-by: Christoph Hellwig <hch@lst.de>

-- 

 fs/xfs/linux-2.6/xfs_file.c  |  134 +++++++------------------------------------
 fs/xfs/linux-2.6/xfs_ioctl.c |    3 
 fs/xfs/linux-2.6/xfs_iops.h  |    1 
 include/linux/fs.h           |    2 
 4 files changed, 28 insertions(+), 112 deletions(-)

Index: linux-2.6/fs/xfs/linux-2.6/xfs_ioctl.c
===================================================================
--- linux-2.6.orig/fs/xfs/linux-2.6/xfs_ioctl.c	2008-11-12 00:59:25.000000000 +0530
+++ linux-2.6/fs/xfs/linux-2.6/xfs_ioctl.c	2008-11-28 16:11:30.000000000 +0530
@@ -326,10 +326,11 @@ xfs_open_by_handle(
 		put_unused_fd(new_fd);
 		return -XFS_ERROR(-PTR_ERR(filp));
 	}
+
 	if (inode->i_mode & S_IFREG) {
 		/* invisible operation should not change atime */
 		filp->f_flags |= O_NOATIME;
-		filp->f_op = &xfs_invis_file_operations;
+		filp->f_mode |= FMODE_INVISIBLE;
 	}
 
 	fd_install(new_fd, filp);
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h	2008-11-28 16:04:52.000000000 +0530
+++ linux-2.6/include/linux/fs.h	2008-11-28 16:04:53.000000000 +0530
@@ -81,6 +81,8 @@ extern int dir_notify_enable;
 /* File is opened using open(.., 3, ..) and is writeable only for ioctls
    (specialy hack for floppy.c) */
 #define FMODE_WRITE_IOCTL	((__force fmode_t)128)
+/* Invisible I/O - special hack for XFS ioctls */
+#define FMODE_INVISIBLE		((__force fmode_t)256)
 
 #define RW_MASK		1
 #define RWA_MASK	2
Index: linux-2.6/fs/xfs/linux-2.6/xfs_file.c
===================================================================
--- linux-2.6.orig/fs/xfs/linux-2.6/xfs_file.c	2008-11-28 16:04:59.000000000 +0530
+++ linux-2.6/fs/xfs/linux-2.6/xfs_file.c	2008-11-28 16:08:27.000000000 +0530
@@ -44,81 +44,45 @@
 
 static struct vm_operations_struct xfs_file_vm_ops;
 
-STATIC_INLINE ssize_t
-__xfs_file_read(
+STATIC ssize_t
+xfs_file_aio_read(
 	struct kiocb		*iocb,
 	const struct iovec	*iov,
 	unsigned long		nr_segs,
-	int			ioflags,
 	loff_t			pos)
 {
 	struct file		*file = iocb->ki_filp;
+	int			ioflags = IO_ISAIO;
 
 	BUG_ON(iocb->ki_pos != pos);
 	if (unlikely(file->f_flags & O_DIRECT))
 		ioflags |= IO_ISDIRECT;
+	if (file->f_mode |= FMODE_INVISIBLE)
+		ioflags |= IO_INVIS;
 	return xfs_read(XFS_I(file->f_path.dentry->d_inode), iocb, iov,
 				nr_segs, &iocb->ki_pos, ioflags);
 }
 
 STATIC ssize_t
-xfs_file_aio_read(
-	struct kiocb		*iocb,
-	const struct iovec	*iov,
-	unsigned long		nr_segs,
-	loff_t			pos)
-{
-	return __xfs_file_read(iocb, iov, nr_segs, IO_ISAIO, pos);
-}
-
-STATIC ssize_t
-xfs_file_aio_read_invis(
-	struct kiocb		*iocb,
-	const struct iovec	*iov,
-	unsigned long		nr_segs,
-	loff_t			pos)
-{
-	return __xfs_file_read(iocb, iov, nr_segs, IO_ISAIO|IO_INVIS, pos);
-}
-
-STATIC_INLINE ssize_t
-__xfs_file_write(
+xfs_file_aio_write(
 	struct kiocb		*iocb,
 	const struct iovec	*iov,
 	unsigned long		nr_segs,
-	int			ioflags,
 	loff_t			pos)
 {
-	struct file	*file = iocb->ki_filp;
+	struct file		*file = iocb->ki_filp;
+	int			ioflags = IO_ISAIO;
 
 	BUG_ON(iocb->ki_pos != pos);
 	if (unlikely(file->f_flags & O_DIRECT))
 		ioflags |= IO_ISDIRECT;
+	if (file->f_mode |= FMODE_INVISIBLE)
+		ioflags |= IO_INVIS;
 	return xfs_write(XFS_I(file->f_mapping->host), iocb, iov, nr_segs,
 				&iocb->ki_pos, ioflags);
 }
 
 STATIC ssize_t
-xfs_file_aio_write(
-	struct kiocb		*iocb,
-	const struct iovec	*iov,
-	unsigned long		nr_segs,
-	loff_t			pos)
-{
-	return __xfs_file_write(iocb, iov, nr_segs, IO_ISAIO, pos);
-}
-
-STATIC ssize_t
-xfs_file_aio_write_invis(
-	struct kiocb		*iocb,
-	const struct iovec	*iov,
-	unsigned long		nr_segs,
-	loff_t			pos)
-{
-	return __xfs_file_write(iocb, iov, nr_segs, IO_ISAIO|IO_INVIS, pos);
-}
-
-STATIC ssize_t
 xfs_file_splice_read(
 	struct file		*infilp,
 	loff_t			*ppos,
@@ -126,20 +90,13 @@ xfs_file_splice_read(
 	size_t			len,
 	unsigned int		flags)
 {
-	return xfs_splice_read(XFS_I(infilp->f_path.dentry->d_inode),
-				   infilp, ppos, pipe, len, flags, 0);
-}
+	int			ioflags = 0;
+
+	if (infilp->f_mode |= FMODE_INVISIBLE)
+		ioflags |= IO_INVIS;
 
-STATIC ssize_t
-xfs_file_splice_read_invis(
-	struct file		*infilp,
-	loff_t			*ppos,
-	struct pipe_inode_info	*pipe,
-	size_t			len,
-	unsigned int		flags)
-{
 	return xfs_splice_read(XFS_I(infilp->f_path.dentry->d_inode),
-				   infilp, ppos, pipe, len, flags, IO_INVIS);
+				   infilp, ppos, pipe, len, flags, ioflags);
 }
 
 STATIC ssize_t
@@ -150,20 +107,13 @@ xfs_file_splice_write(
 	size_t			len,
 	unsigned int		flags)
 {
-	return xfs_splice_write(XFS_I(outfilp->f_path.dentry->d_inode),
-				    pipe, outfilp, ppos, len, flags, 0);
-}
+	int			ioflags = 0;
+
+	if (outfilp->f_mode |= FMODE_INVISIBLE)
+		ioflags |= IO_INVIS;
 
-STATIC ssize_t
-xfs_file_splice_write_invis(
-	struct pipe_inode_info	*pipe,
-	struct file		*outfilp,
-	loff_t			*ppos,
-	size_t			len,
-	unsigned int		flags)
-{
 	return xfs_splice_write(XFS_I(outfilp->f_path.dentry->d_inode),
-				    pipe, outfilp, ppos, len, flags, IO_INVIS);
+				    pipe, outfilp, ppos, len, flags, ioflags);
 }
 
 STATIC int
@@ -256,29 +206,12 @@ xfs_file_ioctl(
 {
 	int		error;
 	struct inode	*inode = filp->f_path.dentry->d_inode;
+	int			ioflags = 0;
 
-	error = xfs_ioctl(XFS_I(inode), filp, 0, cmd, (void __user *)p);
-	xfs_iflags_set(XFS_I(inode), XFS_IMODIFIED);
+	if (filp->f_mode |= FMODE_INVISIBLE)
+		ioflags |= IO_INVIS;
 
-	/* NOTE:  some of the ioctl's return positive #'s as a
-	 *	  byte count indicating success, such as
-	 *	  readlink_by_handle.  So we don't "sign flip"
-	 *	  like most other routines.  This means true
-	 *	  errors need to be returned as a negative value.
-	 */
-	return error;
-}
-
-STATIC long
-xfs_file_ioctl_invis(
-	struct file	*filp,
-	unsigned int	cmd,
-	unsigned long	p)
-{
-	int		error;
-	struct inode	*inode = filp->f_path.dentry->d_inode;
-
-	error = xfs_ioctl(XFS_I(inode), filp, IO_INVIS, cmd, (void __user *)p);
+	error = xfs_ioctl(XFS_I(inode), filp, ioflags, cmd, (void __user *)p);
 	xfs_iflags_set(XFS_I(inode), XFS_IMODIFIED);
 
 	/* NOTE:  some of the ioctl's return positive #'s as a
@@ -325,25 +258,6 @@ const struct file_operations xfs_file_op
 #endif
 };
 
-const struct file_operations xfs_invis_file_operations = {
-	.llseek		= generic_file_llseek,
-	.read		= do_sync_read,
-	.write		= do_sync_write,
-	.aio_read	= xfs_file_aio_read_invis,
-	.aio_write	= xfs_file_aio_write_invis,
-	.splice_read	= xfs_file_splice_read_invis,
-	.splice_write	= xfs_file_splice_write_invis,
-	.unlocked_ioctl	= xfs_file_ioctl_invis,
-#ifdef CONFIG_COMPAT
-	.compat_ioctl	= xfs_file_compat_invis_ioctl,
-#endif
-	.mmap		= xfs_file_mmap,
-	.open		= xfs_file_open,
-	.release	= xfs_file_release,
-	.fsync		= xfs_file_fsync,
-};
-
-
 const struct file_operations xfs_dir_file_operations = {
 	.read		= generic_read_dir,
 	.readdir	= xfs_file_readdir,
Index: linux-2.6/fs/xfs/linux-2.6/xfs_iops.h
===================================================================
--- linux-2.6.orig/fs/xfs/linux-2.6/xfs_iops.h	2008-11-28 16:08:37.000000000 +0530
+++ linux-2.6/fs/xfs/linux-2.6/xfs_iops.h	2008-11-28 16:08:42.000000000 +0530
@@ -22,7 +22,6 @@ struct xfs_inode;
 
 extern const struct file_operations xfs_file_operations;
 extern const struct file_operations xfs_dir_file_operations;
-extern const struct file_operations xfs_invis_file_operations;
 
 extern ssize_t xfs_vn_listxattr(struct dentry *, char *data, size_t size);