fs: get rid of base class btrfs_ioctl_same_extent_info

We only use BtrfsExtentInfo when it's exactly equivalent to the
base, so drop the derived class.

While we're here, fix BtrfsExtentSame::add so it uses a btrfs-compatible
uint64_t instead of an off_t.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

include/crucible/fs.h

@@ -27,20 +27,16 @@ namespace crucible {
 	// wrapper around fallocate(...FALLOC_FL_PUNCH_HOLE...)
 	void punch_hole(int fd, off_t offset, off_t len);
 
-	struct BtrfsExtentInfo : public btrfs_ioctl_same_extent_info {
-		BtrfsExtentInfo(int dst_fd, off_t dst_offset);
-	};
-
 	struct BtrfsExtentSame {
 		virtual ~BtrfsExtentSame();
 		BtrfsExtentSame(int src_fd, off_t src_offset, off_t src_length);
-		void add(int fd, off_t offset);
+		void add(int fd, uint64_t offset);
 		virtual void do_ioctl();
 
 		uint64_t m_logical_offset = 0;
 		uint64_t m_length = 0;
 		int m_fd;
-		vector<BtrfsExtentInfo> m_info;
+		vector<btrfs_ioctl_same_extent_info> m_info;
 	};
 
 	ostream & operator<<(ostream &os, const btrfs_ioctl_same_extent_info *info);

lib/fs.cc

@@ -33,18 +33,6 @@ namespace crucible {
 #endif
 	}
 
-	BtrfsExtentInfo::BtrfsExtentInfo(int dst_fd, off_t dst_offset) :
-		btrfs_ioctl_same_extent_info( (btrfs_ioctl_same_extent_info) { } )
-	{
-		assert(fd == 0);
-		assert(logical_offset == 0);
-		assert(bytes_deduped == 0);
-		assert(status == 0);
-		assert(reserved == 0);
-		fd = dst_fd;
-		logical_offset = dst_offset;
-	}
-
 	BtrfsExtentSame::BtrfsExtentSame(int src_fd, off_t src_offset, off_t src_length) :
 		m_logical_offset(src_offset),
 		m_length(src_length),
@@ -57,9 +45,12 @@ namespace crucible {
 	}
 
 	void
-	BtrfsExtentSame::add(int fd, off_t offset)
+	BtrfsExtentSame::add(int const fd, uint64_t const offset)
 	{
-		m_info.push_back(BtrfsExtentInfo(fd, offset));
+		m_info.push_back( (btrfs_ioctl_same_extent_info) {
+			.fd = fd,
+			.logical_offset = offset,
+		});
 	}
 
 	ostream &