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https://github.com/kdave/btrfs-progs
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56e75c9f75
[BUG]
When enabling extent-tree-v2 feature at mkfs time (need to enable
experimental features), mkfs.btrfs will crash:
# ./mkfs.btrfs -f -O extent-tree-v2 ~/test.img
btrfs-progs v5.19.1
See http://btrfs.wiki.kernel.org for more information.
ERROR: superblock magic doesn't match
NOTE: several default settings have changed in version 5.15, please make sure
this does not affect your deployments:
- DUP for metadata (-m dup)
- enabled no-holes (-O no-holes)
- enabled free-space-tree (-R free-space-tree)
Segmentation fault (core dumped)
[CAUSE]
The block group tree looks like this after make_btrfs() call:
(gdb) call btrfs_print_tree(root->fs_info->block_group_root->node, 0)
leaf 1163264 items 1 free space 16234 generation 1 owner BLOCK_GROUP_TREE
leaf 1163264 flags 0x0() backref revision 1
checksum stored f137c1ac
checksum calced f137c1ac
fs uuid 450d4b15-4954-4574-9801-8c6d248aaec6
chunk uuid 4c4cc54d-f240-4aa4-b88b-bd487db43444
item 0 key (1048576 BLOCK_GROUP_ITEM 4194304) itemoff 16259 itemsize 24
block group used 131072 chunk_objectid 256 flags SYSTEM|single
^^^
This looks completely sane, but notice that chunk_objectid 256.
That 256 value is the expected one for regular non-extent-tree-v2 btrfs,
but for extent-tree-v2, chunk_objectid is reused as the global id of
extent tree where the block group belongs to.
With the old 256 value as chunk_objectid, btrfs will not find an extent
tree root for the block group, and return NULL for btrfs_extent_root()
call, and trigger segfault.
This is a regression caused by commit
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|---|---|---|
| .. | ||
| common.c | ||
| common.h | ||
| main.c | ||
| Makefile | ||
| rootdir.c | ||
| rootdir.h | ||