btrfs: clear BTRFS_ROOT_IN_TRANS_SETUP on early exit from record_root_in_trans()

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If we exit early because the transaction that last used the root already
matches the current transaction, we leave the BTRFS_ROOT_IN_TRANS_SETUP
bit set in the root (which we just set right before the exit). While this
does not cause any functional issue, it makes callers of
btrfs_record_root_in_trans() lock fs_info->reloc_mutex and call
record_root_in_trans() for nothing, causing unnecessary lock contention,
until one of them clears the bit in record_root_in_trans().
One caller of btrfs_record_root_in_trans() is start_transaction(), used to
start new transaction or joining an existing one, which is a hot path.

So clear BTRFS_ROOT_IN_TRANS_SETUP on early exit.

Assisted-by: LLM
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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Filipe Manana 2026-09-18 11:58:00 +01:00 • committed by David Sterba

parent 72de4807ba

commit 3e6ff34afc

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fs/btrfs/transaction.c

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