linux-kernel - Re: [PATCH v3] btrfs: zoned: remove redundant space_info lock and variable in do_allocation

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Message-ID: <20260204144006.GT26902@twin.jikos.cz>
Date: Wed, 4 Feb 2026 15:40:06 +0100
From: David Sterba <dsterba@...e.cz>
To: Jiasheng Jiang <jiashengjiangcool@...il.com>
Cc: naohiro.aota@....com, boris@....io, clm@...com, dsterba@...e.com,
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] btrfs: zoned: remove redundant space_info lock and
 variable in do_allocation_zoned

On Wed, Jan 14, 2026 at 02:44:50PM +0000, Jiasheng Jiang wrote:
> In do_allocation_zoned(), the code acquires space_info->lock before
> block_group->lock. However, the critical section does not access or
> modify any members of the space_info structure. Thus, the lock is
> redundant as it provides no necessary synchronization here.
> 
> This change simplifies the locking logic and aligns the function with
> other zoned paths, such as __btrfs_add_free_space_zoned(), which only
> rely on block_group->lock. Since the 'space_info' local variable is
> no longer used after removing the lock calls, it is also removed.
> 
> Removing this unnecessary lock reduces contention on the global
> space_info lock, improving concurrency in the zoned allocation path.
> 
> Signed-off-by: Jiasheng Jiang <jiashengjiangcool@...il.com>

Added to for-next, thanks.