xfs: Introduce XFS_IOC_ZERO_RANGE

XFS_IOC_ZERO_RANGE is the equivalent of an atomic XFS_IOC_UNRESVSP/
XFS_IOC_RESVSP call pair. It enabled ranges of written data to be
turned into zeroes without requiring IO or having to free and
reallocate the extents in the range given as would occur if we had
to punch and then preallocate them separately.  This enables
applications to zero parts of files very quickly without changing
the layout of the files in any way.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

2 files changed, 3 insertions, 1 deletions

diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index 3b9e626f7cd1..03aa908a9cb9 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -1301,7 +1301,8 @@ xfs_file_ioctl(
         case XFS_IOC_ALLOCSP64:
         case XFS_IOC_FREESP64:
         case XFS_IOC_RESVSP64:
-        case XFS_IOC_UNRESVSP64: {
+        case XFS_IOC_UNRESVSP64:
+        case XFS_IOC_ZERO_RANGE: {
                 xfs_flock64_t           bf;
 
                 if (copy_from_user(&bf, arg, sizeof(bf)))
diff --git a/fs/xfs/linux-2.6/xfs_ioctl32.c b/fs/xfs/linux-2.6/xfs_ioctl32.c
index 6c83f7f62dc9..464bcc76e980 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl32.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl32.c
@@ -574,6 +574,7 @@ xfs_file_compat_ioctl(
         case XFS_IOC_FSGEOMETRY_V1:
         case XFS_IOC_FSGROWFSDATA:
         case XFS_IOC_FSGROWFSRT:
+        case XFS_IOC_ZERO_RANGE:
                 return xfs_file_ioctl(filp, cmd, p);
 #else
         case XFS_IOC_ALLOCSP_32: