[PATCH] Add preallocation beyond EOF to fallocate

[David Chinner <dgc@xxxxxxx>]

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@xxxxxxx>

---
 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__