From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f49.google.com (mail-ej1-f49.google.com [209.85.218.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 92CEE432BE4 for ; Mon, 14 Sep 2026 10:21:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789381289; cv=none; b=s7YlKJoV3VOeTA/qjqyih5CZjzvT94bIMHrbvBRAlre2Wj3n+XP6Ucuh868jLqaHoxORyTsQdf6CYlT1KjnqL60Out0rf1lWcQ/he3OZQktfaYh/KISQKx3r97hj1Zihx4ciA5shYib3GWzOf40r3mEWb+KwChtPByxPo9XEpyA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789381289; c=relaxed/simple; bh=VXpebVg7Nldh5Ep1tWZVhxBQDrVdUqDA7c+yyDSAqpg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DCtHSDy/uakQR+jVziFevZL1vRTZ1zagz16k2eYBKXOO17fsG6sl01CzU+J9UqA2MbDHfL303PT5a79/ZPwLDPnQpdpav8RZGQ4RHxW5w7vMzVxkuO3qn5ooWNqMzUjVuJ+NdchB+i3+2dRq21cpOuMiBfF0lcwzEwCBJU7hfdU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=eo+o13Ft; arc=none smtp.client-ip=209.85.218.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="eo+o13Ft" Received: by mail-ej1-f49.google.com with SMTP id a640c23a62f3a-c2940d16190so431653066b.3 for ; Mon, 14 Sep 2026 03:21:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1789381286; x=1789986086; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=OO5pmXKOT9/i4mss78wiYzQWJEasfIGqq/r4oOGiH8I=; b=eo+o13Ftq46zYl7f+RMlklZfmmBTSocZOeRafSTzap0NlBAVAZ8ASy2yf/Q4Ec8r4F cjcXtsqUSX9t1Oa1HUXi9u5QArWhyqg3aWRQS0CHtKzC0gqVcJI4iBSAqziFQGjTS4y9 7Rwj0cjcbhOmAnhMb4ChhORR+KqFZ5kwmlZ5oAs5j/0hAmhTwUYe17WoICasZQcB2yYX enWYAq+DQUtgh/8l3zlzWSnvt+ZHXMuxuxlk+mq9/G5dltsCsr+i04OpDB5iTzVLlaJZ tLsM1/rRtQAn8fyDoPf5ruIrKZ4FvazCVoVFcgZLy5gZfdGo5ME8T8DSmp5EQcqwrF8M XTag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1789381286; x=1789986086; h=content-transfer-encoding:content-type:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=OO5pmXKOT9/i4mss78wiYzQWJEasfIGqq/r4oOGiH8I=; b=pEB4LcW9bA84P9kezIN7gXatohFokyRrhlm0B2JNJ9HvL6MUnVrlBiUp43ZB/9QWaP dBAPEAsYc/zpS7aVH/O8R5KDJBu+Z/d4DVf0N981290QdFVS0D+TUp8fF9ZuJ77pQndr VHdhRnpNQqZPHtorYOgsnX0cT+tygw0kKNxkdbTzbfkJ4zTAhDVppCAZ9iNRO4PtMNK2 2w+kkmb704/eDRf+nKPSeM1h7P6z34kJYKaTzKq1wGL+yUuxwZUo07hzmhFbuNi6tpjS T+OH0E1ayL6La4D7kbxfKiqZcSTL7oywUUwEvcYU1UctSv+cZQChaN1X7kqNF/L7tddb xh3w== X-Forwarded-Encrypted: i=1; AKwUvBxE5EdtyO8iDdPOIml7Xq4pYz9bPuwhQ78Hzvu+J6olMX3sqEpKTSuey9Io3HJX7R1n1WkF8Frk5SxWFAs=@vger.kernel.org X-Gm-Message-State: AFuF++kLU5YiqWRu7aD4Epneo8VeNKEmHi+C2SSRVR1su4p1FvNYIhph Huht7MXXg3jDsWuQt6sERV8VzheyieGdtX7HygOkXJnswxquRGQrJrulLMXzoPbjYrP7xIXjyvV wQLvdfXE= X-Gm-Gg: AYBFou0FQSb6yTpotdljMVq4AGa/7H/+hCEvX3VlMDRRibnJ8tplRWxUgY7AGu6YvEj omRgNrPQDEw+fl4P9OHld/i7J2IdXFhl2n+I8kTQkNZ7iGvp/k8UCyxZAk4TQfVOwyGAhybnBVm ztfFJz33P6O85SqS7PRkDZfSA+4o2qAALBVRx5TOflXuxnF1xckeYevwL5VY9wVtuhs1G/Dejm9 RIgmusvAZI123b4dT9AJyDUykGKFoCOHhdsCX8zCZW6IOSDa+7zQJ3IqnEyLrFpT3RgatP6YqZu 4N+U//xbBBTTuo+1LzefykIP+ITvGLQ0iMHtIfS9Y72M2OLMxdT8f8PImMA/q9UfERSivEVnuqy zRwcKDn+rRXMWMZpbHUSk06NqPpXMR5fXdMhe8xxoJlAmzaclsmpeHhRG+Rxoe3dVZ+yLDtir1D 1EGF+vJXbDM6rFV+xUNUbhQGJgGq2Q7A9KhRE99hPtYuJF/lCVQ7o67yyIyFQTD7c= X-Received: by 2002:a17:906:eec8:b0:c26:19e3:e981 with SMTP id a640c23a62f3a-c29b875e5b6mr121146566b.33.1789381285743; Mon, 14 Sep 2026 03:21:25 -0700 (PDT) Received: from [172.16.0.229] ([159.196.52.54]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39d9959ac65sm19856927a91.16.2026.09.14.03.21.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 14 Sep 2026 03:21:24 -0700 (PDT) Message-ID: <3f3209ea-44bf-4dc4-9567-d936703435d2@suse.com> Date: Mon, 14 Sep 2026 19:51:16 +0930 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] btrfs: discard: fix warning for discard_state To: Jiahao Li , dsterba@suse.com, mason@kernel.org Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, Jiahao Li References: <20260914092222.1465563-1-lijiahao202609@163.com> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=wqu@suse.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNGFF1IFdlbnJ1byA8d3F1QHN1c2UuY29tPsLAlAQTAQgAPgIbAwULCQgHAgYVCAkKCwIE FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXVgBQkQ/lqxAAoJEMI9kfOh Jf6o+jIH/2KhFmyOw4XWAYbnnijuYqb/obGae8HhcJO2KIGcxbsinK+KQFTSZnkFxnbsQ+VY fvtWBHGt8WfHcNmfjdejmy9si2jyy8smQV2jiB60a8iqQXGmsrkuR+AM2V360oEbMF3gVvim 2VSX2IiW9KERuhifjseNV1HLk0SHw5NnXiWh1THTqtvFFY+CwnLN2GqiMaSLF6gATW05/sEd V17MdI1z4+WSk7D57FlLjp50F3ow2WJtXwG8yG8d6S40dytZpH9iFuk12Sbg7lrtQxPPOIEU rpmZLfCNJJoZj603613w/M8EiZw6MohzikTWcFc55RLYJPBWQ+9puZtx1DopW2jOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXWBBQkQ/lrSAAoJEMI9kfOhJf6o cakH+QHwDszsoYvmrNq36MFGgvAHRjdlrHRBa4A1V1kzd4kOUokongcrOOgHY9yfglcvZqlJ qfa4l+1oxs1BvCi29psteQTtw+memmcGruKi+YHD7793zNCMtAtYidDmQ2pWaLfqSaryjlzR /3tBWMyvIeWZKURnZbBzWRREB7iWxEbZ014B3gICqZPDRwwitHpH8Om3eZr7ygZck6bBa4MU o1XgbZcspyCGqu1xF/bMAY2iCDcq6ULKQceuKkbeQ8qxvt9hVxJC2W3lHq8dlK1pkHPDg9wO JoAXek8MF37R8gpLoGWl41FIUb3hFiu3zhDDvslYM4BmzI18QgQTQnotJH8= In-Reply-To: <20260914092222.1465563-1-lijiahao202609@163.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/9/14 18:52, Jiahao Li 写道: > From: Jiahao Li > > Building with -Werror=mabe-uninitialized fails: > fs/btrfs/discard.c:553:9: error: 'discard_state' may be used > uninitialized [-Werror=maybe-uninitialized] > > The compiler cannot prove that discard_state is assigned on every path > before it is read. Compiler and its version, a lot of times such false alerts are just compiler version dependent. In my case, gcc 16.2.1 failed to reproduced this false alert. Initialize it to BTRFS_DISCARD_EXTENTS, which is the > state the variable holds when the loop is first entered, this does not > change runtime behavior, so the warning is gone and the value is always > well defined. It's a false alert. Firstly if peek_discard_list() didn't find a bg, btrfs_discard_workfn() returned immediately. Secondly if a bg is found in peek_discard_list(), *discard_state is fetched from bg's discard_state. So all paths should be fine. > > Signed-off-by: Jiahao Li > --- > fs/btrfs/discard.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c > index 1c304bf473e5..413a804ff46b 100644 > --- a/fs/btrfs/discard.c > +++ b/fs/btrfs/discard.c > @@ -519,7 +519,7 @@ static void btrfs_discard_workfn(struct work_struct *work) > { > struct btrfs_discard_ctl *discard_ctl; > struct btrfs_block_group *block_group; > - enum btrfs_discard_state discard_state; > + enum btrfs_discard_state discard_state = BTRFS_DISCARD_EXTENTS; > int discard_index = 0; > u64 trimmed = 0; > u64 minlen = 0;