From 87128f520a6b7573f8086f2c89b9381ee7e85e51 Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@suse.com>
Date: Mon, 10 Jun 2024 06:22:56 +0930
Subject: [PATCH] btrfs: uapi: record temporary super flags used by btrfstune
[BUG]
There is a bug report that a canceled checksum conversion (still
experimental feature) results in unexpected super block flags:
csum_type 0 (crc32c)
csum_size 4
csum 0x14973811 [match]
bytenr 65536
flags 0x1000000001
( WRITTEN |
CHANGING_FSID_V2 )
magic _BHRfS_M [match]
While for a filesystem with ongoing checksum conversion it should have
either CHANGING_DATA_CSUM or CHANGING_META_CSUM.
[CAUSE]
It turns out that, due to btrfs-progs keeps its own extra flags inside
its own ctree.h headers, not the shared uapi headers, we have
conflicting super flags:
kernel-shared/uapi/btrfs_tree.h:#define BTRFS_SUPER_FLAG_METADUMP_V2 (1ULL << 34)
kernel-shared/uapi/btrfs_tree.h:#define BTRFS_SUPER_FLAG_CHANGING_FSID (1ULL << 35)
kernel-shared/uapi/btrfs_tree.h:#define BTRFS_SUPER_FLAG_CHANGING_FSID_V2 (1ULL << 36)
kernel-shared/ctree.h:#define BTRFS_SUPER_FLAG_CHANGING_DATA_CSUM (1ULL << 36)
kernel-shared/ctree.h:#define BTRFS_SUPER_FLAG_CHANGING_META_CSUM (1ULL << 37)
Note that CHANGING_FSID_V2 is conflicting with CHANGING_DATA_CSUM.
[FIX]
The proper fix would be done inside btrfs-progs, but to keep everything
properly recorded, we should have everything inside the same uapi
header.
Copy all the new flags into uapi header, and change the value for
CHANGING_DATA_CSUM and CHANGING_META_CSUM, while keep the value of
CHANGING_BG_TREE untouched.
Thankfully checksum change is still only experimental and all those
CHANGING_* flags are transient (only for btrfs-progs to resume the
conversion, and kernel will reject them all), the damage is still minor.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
include/uapi/linux/btrfs_tree.h | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index d24e8e121507b..c7636331e5669 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -777,6 +777,14 @@ struct btrfs_stripe_extent {
#define BTRFS_SUPER_FLAG_CHANGING_FSID (1ULL << 35)
#define BTRFS_SUPER_FLAG_CHANGING_FSID_V2 (1ULL << 36)
+/*
+ * Those are temporaray flags utilized by btrfs-progs to do offline conversion.
+ * They are rejected by kernel.
+ * But still keep them all here to avoid conflicts.
+ */
+#define BTRFS_SUPER_FLAG_CHANGING_BG_TREE (1ULL << 38)
+#define BTRFS_SUPER_FLAG_CHANGING_DATA_CSUM (1ULL << 39)
+#define BTRFS_SUPER_FLAG_CHANGING_META_CSUM (1ULL << 40)
/*
* items in the extent btree are used to record the objectid of the
--
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