btrfs-progs: add test to fsck-tests/063-log-missing-csum where csum a…

…lready present

Adds a test that btrfs check doesn't report an error because of a
missing csum entry in the log tree, if that csum is already in the
normal csum tree. See commit 6c7d2a3.

The checksum tree in already-present.img.xz:

checksum tree key (CSUM_TREE ROOT_ITEM 0)
leaf 5390336 items 1 free space 16254 generation 5 owner CSUM_TREE
leaf 5390336 flags 0x1(WRITTEN) backref revision 1
checksum stored ff20c282
checksum calced ff20c282
fs uuid 70d417f0-0173-49ca-bdf1-b789a798974d
chunk uuid b7ec3806-ea09-4f18-a5ef-126a2d79105e
        item 0 key (EXTENT_CSUM EXTENT_CSUM 13631488) itemoff 16279 itemsize 4
                range start 13631488 end 13635584 length 4096

The log tree in already-present.img.xz:

log tree key (TREE_LOG ROOT_ITEM 5)
leaf 5373952 items 3 free space 15981 generation 7 owner TREE_LOG
leaf 5373952 flags 0x1(WRITTEN) backref revision 1
checksum stored 63afa0e5
checksum calced 63afa0e5
fs uuid 70d417f0-0173-49ca-bdf1-b789a798974d
chunk uuid b7ec3806-ea09-4f18-a5ef-126a2d79105e
        item 0 key (257 INODE_ITEM 0) itemoff 16123 itemsize 160
                generation 7 transid 7 size 4096 nbytes 0
                block group 0 mode 100644 links 1 uid 0 gid 0 rdev 0
                sequence 1 flags 0x0(none)
                atime 1721050040.375996658 (2024-07-15 14:27:20)
                ctime 1721050040.375996658 (2024-07-15 14:27:20)
                mtime 1721050040.375996658 (2024-07-15 14:27:20)
                otime 0.2820488960 (1970-01-01 01:00:00)
        item 1 key (257 INODE_REF 256) itemoff 16109 itemsize 14
                index 2 namelen 4 name: file
        item 2 key (257 EXTENT_DATA 0) itemoff 16056 itemsize 53
                generation 7 type 1 (regular)
                extent data disk byte 13631488 nr 4096
                extent data offset 0 nr 4096 ram 4096
                extent compression 0 (none)

Signed-off-by: Mark Harmstone <[email protected]>