fs/ntfs3: Keep preallocated only if option prealloc enabled

If size of file was reduced, we still kept allocated blocks.
This commit makes ntfs3 work as other fs like btrfs.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214719
Fixes: 4342306f ("fs/ntfs3: Add file operations and implementation")
Reported-by: Ganapathi Kamath <hgkamath@hotmail.com>
Tested-by: Ganapathi Kamath <hgkamath@hotmail.com>
Reviewed-by: Kari Argillander <kari.argillander@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/file.c

@@ -494,7 +494,7 @@ static int ntfs_truncate(struct inode *inode, loff_t new_size)
 
 	down_write(&ni->file.run_lock);
 	err = attr_set_size(ni, ATTR_DATA, NULL, 0, &ni->file.run, new_size,
-			    &new_valid, true, NULL);
+			    &new_valid, ni->mi.sbi->options->prealloc, NULL);
 	up_write(&ni->file.run_lock);
 
 	if (new_valid < ni->i_valid)