btrfs: check block group before marking it unused in balance_remap_chunks()

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Fix a potential segfault in balance_remap_chunks(): if we quit early
because btrfs_inc_block_group_ro() fails, all the remaining items in the
chunks list will still have their bg value set to NULL. It's thus not
safe to dereference this pointer without checking first.

Reported-by: Chris Mason <clm@fb.com>
Link: https://lore.kernel.org/linux-btrfs/20260125120717.1578828-1-clm@meta.com/
Fixes: 81e5a4551c ("btrfs: allow balancing remap tree")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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Mark Harmstone 2026-02-19 19:19:00 +00:00 • committed by David Sterba

parent 057495ccc0

commit adbb0ebacc

1 changed files with 17 additions and 8 deletions

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fs/btrfs/volumes.c

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