From 5953ea6d3c564686c3ed1f1edd1e3ff72ca694d6 Mon Sep 17 00:00:00 2001
From: Zygo Blaxell <bees@furryterror.org>
Date: Mon, 24 Oct 2022 11:48:35 -0400
Subject: [PATCH] fs: update btrfs compatibility header: add csum types,
 BTRFS_FS_INFO_FLAG_GENERATION and _METADATA_UUID

I guess this means it's "args_v3" now?

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
---
 include/crucible/btrfs.h | 27 +++++++++++++++++++++++++--
 include/crucible/fs.h    |  3 ++-
 lib/fs.cc                | 19 ++++++++++++++-----
 3 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/include/crucible/btrfs.h b/include/crucible/btrfs.h
index 798c4b7..f8c9408 100644
--- a/include/crucible/btrfs.h
+++ b/include/crucible/btrfs.h
@@ -216,7 +216,28 @@ enum btrfs_compression_type {
 	#define BTRFS_FS_INFO_FLAG_CSUM_INFO                    (1 << 0)
 #endif
 
-struct btrfs_ioctl_fs_info_args_v2 {
+#ifndef BTRFS_FS_INFO_FLAG_GENERATION
+/* Request information about filesystem generation */
+#define BTRFS_FS_INFO_FLAG_GENERATION                   (1 << 1)
+#endif
+
+#ifndef BTRFS_FS_INFO_FLAG_METADATA_UUID
+/* Request information about filesystem metadata UUID */
+#define BTRFS_FS_INFO_FLAG_METADATA_UUID                (1 << 2)
+#endif
+
+// BTRFS_CSUM_TYPE_CRC32 was a #define from 2008 to 2019.
+// After that, it's an enum with the other 3 types.
+// So if we do _not_ have CRC32 defined, it means we have the other 3;
+// if we _do_ have CRC32 defined, it means we need the other 3.
+// This seems likely to break some day.
+#ifdef BTRFS_CSUM_TYPE_CRC32
+	#define BTRFS_CSUM_TYPE_XXHASH 1
+	#define BTRFS_CSUM_TYPE_SHA256 2
+	#define BTRFS_CSUM_TYPE_BLAKE2 3
+#endif
+
+struct btrfs_ioctl_fs_info_args_v3 {
 	__u64 max_id;                           /* out */
 	__u64 num_devices;                      /* out */
 	__u8 fsid[BTRFS_FSID_SIZE];             /* out */
@@ -227,7 +248,9 @@ struct btrfs_ioctl_fs_info_args_v2 {
 	__u16 csum_type;                        /* out */
 	__u16 csum_size;                        /* out */
 	__u64 flags;                            /* in/out */
-	__u8 reserved[968];                     /* pad to 1k */
+	__u64 generation;                       /* out */
+	__u8 metadata_uuid[BTRFS_FSID_SIZE];    /* out */
+	__u8 reserved[944];                     /* pad to 1k */
 };
 
 #endif // CRUCIBLE_BTRFS_H
diff --git a/include/crucible/fs.h b/include/crucible/fs.h
index 0b34619..c3a91df 100644
--- a/include/crucible/fs.h
+++ b/include/crucible/fs.h
@@ -248,11 +248,12 @@ namespace crucible {
 
 	template<class V> ostream &hexdump(ostream &os, const V &v);
 
-	struct BtrfsIoctlFsInfoArgs : public btrfs_ioctl_fs_info_args_v2 {
+	struct BtrfsIoctlFsInfoArgs : public btrfs_ioctl_fs_info_args_v3 {
 		BtrfsIoctlFsInfoArgs();
 		void do_ioctl(int fd);
 		uint16_t csum_type() const;
 		uint16_t csum_size() const;
+		uint64_t generation() const;
 	};
 
 	ostream & operator<<(ostream &os, const BtrfsIoctlFsInfoArgs &a);
diff --git a/lib/fs.cc b/lib/fs.cc
index 902b056..a630d50 100644
--- a/lib/fs.cc
+++ b/lib/fs.cc
@@ -1136,8 +1136,11 @@ namespace crucible {
 	};
 
 	BtrfsIoctlFsInfoArgs::BtrfsIoctlFsInfoArgs() :
-		btrfs_ioctl_fs_info_args_v2( (btrfs_ioctl_fs_info_args_v2) {
-			.flags = BTRFS_FS_INFO_FLAG_CSUM_INFO,
+		btrfs_ioctl_fs_info_args_v3( (btrfs_ioctl_fs_info_args_v3) {
+			.flags = 0
+				| BTRFS_FS_INFO_FLAG_CSUM_INFO
+				| BTRFS_FS_INFO_FLAG_GENERATION
+			,
 		})
 	{
 	}
@@ -1145,7 +1148,7 @@ namespace crucible {
 	void
 	BtrfsIoctlFsInfoArgs::do_ioctl(int fd)
 	{
-		btrfs_ioctl_fs_info_args_v2 *p = static_cast<btrfs_ioctl_fs_info_args_v2 *>(this);
+		btrfs_ioctl_fs_info_args_v3 *p = static_cast<btrfs_ioctl_fs_info_args_v3 *>(this);
 		if (ioctl(fd, BTRFS_IOC_FS_INFO, p)) {
 			THROW_ERRNO("BTRFS_IOC_FS_INFO: fd " << fd);
 		}
@@ -1154,13 +1157,19 @@ namespace crucible {
 	uint16_t
 	BtrfsIoctlFsInfoArgs::csum_type() const
 	{
-		return this->btrfs_ioctl_fs_info_args_v2::csum_type;
+		return this->btrfs_ioctl_fs_info_args_v3::csum_type;
 	}
 
 	uint16_t
 	BtrfsIoctlFsInfoArgs::csum_size() const
 	{
-		return this->btrfs_ioctl_fs_info_args_v2::csum_size;
+		return this->btrfs_ioctl_fs_info_args_v3::csum_size;
+	}
+
+	uint64_t
+	BtrfsIoctlFsInfoArgs::generation() const
+	{
+		return this->btrfs_ioctl_fs_info_args_v3::generation;
 	}
 
 };