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btrfs: uapi: record temporary super flags used by btrfstune

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[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>
This commit is contained in:
Qu Wenruo 2024-06-10 06:22:56 +09:30 committed by David Sterba
parent 33b804fae7
commit 87128f520a
1 changed files with 8 additions and 0 deletions
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8
include/uapi/linux/btrfs_tree.h
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@ -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