xfs: unshare a range of blocks via fallocate

Unshare all shared extents if the user calls fallocate with the new
unshare mode flag set, so that we can guarantee that a subsequent
write will not ENOSPC.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[hch: pass inode instead of file to xfs_reflink_dirty_range,
      use iomap infrastructure for copy up]
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index df82b20..bade5a6 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -48,5 +48,9 @@
 extern int xfs_reflink_remap_range(struct xfs_inode *src, xfs_off_t srcoff,
 		struct xfs_inode *dest, xfs_off_t destoff, xfs_off_t len,
 		unsigned int flags);
+extern int xfs_reflink_clear_inode_flag(struct xfs_inode *ip,
+		struct xfs_trans **tpp);
+extern int xfs_reflink_unshare(struct xfs_inode *ip, xfs_off_t offset,
+		xfs_off_t len);
 
 #endif /* __XFS_REFLINK_H */