From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 013.lax.mailroute.net (013.lax.mailroute.net [199.89.1.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 812E0396B9A for ; Wed, 25 Mar 2026 21:37:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774474667; cv=none; b=AhRiqEwKeVTDLG9V/9K46tRAmtIpykykYCYXFRCjac9yoL+lvRXA0cPh44LgPKFbgPy+TKYFz+TLsGmscPs2qf1GC1ozOuujk5jF1m3/58INgKKsJfSn3JBhmEPXHV1Zm3s7RwcioJ2O7ri0FoSxPrFYpl7LLerJ4fDPNCIRl10= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774474667; c=relaxed/simple; bh=FJ6UCAha3g867AQDfyJRQz4YFbWvok19qxKEtBjwcts=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fCbo98Bd5jISN2T5N5JZONwBJ85emcbpWWR7LFteRrSxJriF3hjXBOuBevx6y8K4RzZ5j3KzN2N/dAFmkIdP7a8KNQ1FRCcsJj2qjdaa11zo5mqYJLjo79Ewj30fisj9St/O2qDDj+qV5Cgv4MpTZkX0ds0DNYj7xv5klANRaBk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=gIph/BGi; arc=none smtp.client-ip=199.89.1.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="gIph/BGi" Received: from localhost (localhost [127.0.0.1]) by 013.lax.mailroute.net (Postfix) with ESMTP id 4fh0ck3G7Bzlfddm; Wed, 25 Mar 2026 21:37:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:mime-version:references:in-reply-to :x-mailer:message-id:date:date:subject:subject:from:from :received:received; s=mr01; t=1774474659; x=1777066660; bh=WqQG4 XSh3Lo0qwC2t05jAqXV91txu0Q3n95/qsVqXuc=; b=gIph/BGiNHap/Bw8/b1bn Ya7BVeftBsD/dNKpKW28xNAcSQPlvwQHWteO5mwlMUAGvM2iBATC4NlVOIX8jPfE SPIKJr+g4qNvbQG8aFI/jorp77+PrTV1VjnssaP67OGip5QtaNWj9z2VcYRFZuB5 xo+33PNnC+Be1Ciellh95VXdKGgZxR3TQM8C8KmI0RaybQwTeHf85emcfTXKUONK rW89wVqbWQouSoD3RTa1EELOR6hRRcwLP/89uQMwjRbFTFYIOWdrEn3/tgnk2ZLJ Sk4NfpuT2M9XJlE96Skkuj4i/uD4lBOb28vI1KqnZPEHuX+btzMy8/xg7LFC8e9c Q== X-Virus-Scanned: by MailRoute Received: from 013.lax.mailroute.net ([127.0.0.1]) by localhost (013.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id pj1DOKH49aUY; Wed, 25 Mar 2026 21:37:39 +0000 (UTC) Received: from bvanassche.mtv.corp.google.com (unknown [104.135.180.219]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 013.lax.mailroute.net (Postfix) with ESMTPSA id 4fh0cd4Y3PzlfgQJ; Wed, 25 Mar 2026 21:37:37 +0000 (UTC) From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Damien Le Moal , Ming Lei , Bart Van Assche Subject: [PATCH v2 4/5] block: Reduce the minimum value for the maximum DMA segment size Date: Wed, 25 Mar 2026 14:37:14 -0700 Message-ID: <20260325213719.2850619-5-bvanassche@acm.org> X-Mailer: git-send-email 2.53.0.1018.g2bb0e51243-goog In-Reply-To: <20260325213719.2850619-1-bvanassche@acm.org> References: <20260325213719.2850619-1-bvanassche@acm.org> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable All block devices that are supported by the Linux kernel have a DMA engin= e that supports DMA segments of 4 KiB or larger. Allow smaller DMA segment sizes because these are useful for block layer testing. Reject values bel= ow 512 because such values would result in an excessive number of DMA segmen= ts. The only code affected by this change is the following code: if (WARN_ON_ONCE(lim->max_segment_size < BLK_MIN_SEGMENT_SIZE)) return -EINVAL; Cc: Ming Lei Cc: Christoph Hellwig Signed-off-by: Bart Van Assche --- block/blk.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk.h b/block/blk.h index 7082dd5a87f9..7c792c012b0d 100644 --- a/block/blk.h +++ b/block/blk.h @@ -23,7 +23,7 @@ struct elv_change_ctx; #define BLK_DEF_MAX_SECTORS_CAP (SZ_4M >> SECTOR_SHIFT) =20 #define BLK_DEV_MAX_SECTORS (LLONG_MAX >> 9) -#define BLK_MIN_SEGMENT_SIZE 4096 +#define BLK_MIN_SEGMENT_SIZE 512 =20 /* Max future timer expiry for timeouts */ #define BLK_MAX_TIMEOUT (5 * HZ)