We're currently support two paths from VFS to preallocate unwritten
extents(from FS_IOC_RESVSP, or fallocate()), likewise, behavior of
punching-hole should be treated as the same, this patch tries to teach
file_ioctl() to handle FS_IOC_UNRESVSP, underlying filesystem like ocfs2
is wise enough to do the rest of work;-)

Signed-off-by: Tristan Ye<redacted>
---
  fs/ioctl.c             |   10 +++++++---
  include/linux/falloc.h |    2 ++
  2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 1d9b9fc..234e26f 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c

@@ -422,7 +422,7 @@ EXPORT_SYMBOL(generic_block_fiemap);
   * Only the l_start, l_len and l_whence fields of the 'struct space_resv'
   * are used here, rest are ignored.
   */
-int ioctl_preallocate(struct file *filp, void __user *argp)
+int ioctl_preallocate(struct file *filp, void __user *argp, int mode)
  {
  	struct inode *inode = filp->f_path.dentry->d_inode;
  	struct space_resv sr;

@@ -443,7 +443,7 @@ int ioctl_preallocate(struct file *filp, void __user *argp)
  		return -EINVAL;
  	}

-	return do_fallocate(filp, FALLOC_FL_KEEP_SIZE, sr.l_start, sr.l_len);
+	return do_fallocate(filp, mode, sr.l_start, sr.l_len);
  }

  static int file_ioctl(struct file *filp, unsigned int cmd,

@@ -459,7 +459,11 @@ static int file_ioctl(struct file *filp, unsigned int cmd,
  		return put_user(i_size_read(inode) - filp->f_pos, p);
  	case FS_IOC_RESVSP:
  	case FS_IOC_RESVSP64:
-		return ioctl_preallocate(filp, p);
+		return ioctl_preallocate(filp, p, FALLOC_FL_KEEP_SIZE);
+	case FS_IOC_UNRESVSP:
+	case FS_IOC_UNRESVSP64:
+		return ioctl_preallocate(filp, p, FALLOC_FL_KEEP_SIZE |
+						  FALLOC_FL_PUNCH_HOLE);
  	}

  	return vfs_ioctl(filp, cmd, arg);

diff --git a/include/linux/falloc.h b/include/linux/falloc.h
index 73e0b62..fd1e871 100644
--- a/include/linux/falloc.h
+++ b/include/linux/falloc.h

@@ -21,7 +21,9 @@ struct space_resv {
  };

  #define FS_IOC_RESVSP		_IOW('X', 40, struct space_resv)
+#define FS_IOC_UNRESVSP		_IOW('X', 41, struct space_resv)
  #define FS_IOC_RESVSP64		_IOW('X', 42, struct space_resv)
+#define FS_IOC_UNRESVSP64	_IOW('X', 43, struct space_resv)

  #endif /* __KERNEL__ */