CVE-2026-98245 btrfs: take commit root semaphore when iterating in mark_block_group_to_copy()

In the Linux kernel, the following vulnerability has been resolved: btrfs: take commit root semaphore when iterating in markblockgrouptocopy markblockgrouptocopy iterates over the commit root with skiplocking=true. A concurrent transaction commit can swap and free the commit root during iteration...