[PATCH] Add preallocation beyond EOF to fallocate

[David Chinner <dgc@sgi.com>]

Add new mode to ->fallocate() to allow allocation to occur
beyond the current EOF without changing the file size. Implement
in XFS ->fallocate() vector.

Signed-Off-By: Dave Chinner <dgc@sgi.com>

---
 fs/xfs/linux-2.6/xfs_iops.c |    8 +++++---
 include/linux/fs.h          |    1 +
 2 files changed, 6 insertions(+), 3 deletions(-)

Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_iops.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_iops.c	2007-04-30 11:02:16.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_iops.c	2007-04-30 11:09:48.233375382 +1000
@@ -833,11 +833,13 @@ xfs_vn_fallocate(
 						VNODE_POSITION_XFS);
 
 	switch (mode) {
-	case FA_ALLOCATE: /* changes file size */
-		error = xfs_change_file_space(bdp, XFS_IOC_RESVSP,
-						&bf, 0, NULL, 0);
+	case FA_ALLOCATE:	 /* changes file size */
 		if (offset + len > i_size_read(inode))
 			do_setattr = offset + len;
+		/* FALL THROUGH */
+	case FA_PREALLOCATE:	/* no filesize change */
+		error = xfs_change_file_space(bdp, XFS_IOC_RESVSP,
+						&bf, 0, NULL, 0);
 		break;
 	case FA_DEALLOCATE:
 		/* XXX: changes file size?  this just punches a hole */
Index: 2.6.x-xfs-new/include/linux/fs.h
===================================================================
--- 2.6.x-xfs-new.orig/include/linux/fs.h	2007-04-27 18:48:01.000000000 +1000
+++ 2.6.x-xfs-new/include/linux/fs.h	2007-04-30 11:08:05.790903661 +1000
@@ -269,6 +269,7 @@ extern int dir_notify_enable;
  */
 #define FA_ALLOCATE	0x1
 #define FA_DEALLOCATE	0x2
+#define FA_PREALLOCATE	0x3
 
 #ifdef __KERNEL__
 
-
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