From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 C16E32D4B67 for ; Wed, 25 Jun 2025 16:31:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750869078; cv=none; b=j+QYAtnC3jUkEul9UFLk6e+Ysn8mv/0IGOxxPYqbpenjojKeZk921hpyxadKrbzR4fpnLxDDXqfGqN68RwIW0amqY5knDLELcqxN4uwNjIa2DeoHff7skyeU1Nf/vfYjjayYjb9Sh2HX0tZo/k1Y1OztXhMf7IdkYwAIOUTJ8mw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750869078; c=relaxed/simple; bh=DcVV/T8cztYxvRvFnkyze3vTfAzBA3dxMCVZT2Dxybw=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=DOyvqwdWY8419O2w2VDGQkWHWpFAYMN/7PdQ2aGCLi12nyh42I/dx0vD2t30YnHJvZD9XEeMZkQNYMgPJDeg5X9F8Imag4a3rH74noLJ6VhoU1dVOxSxxsluAcZI2O/tQtpoWhkkBAdveLOBh8kDJueEPOoH2ntVSHAz8Fkp5Cc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=TiFSFFc3; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TiFSFFc3" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750869075; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KZtJBqwq5wZlT1Cguyt5dV46yY0O5gY+TvoWgP3fm6U=; b=TiFSFFc3gV0zR+1g5syRlZ5W3B6SwOERpMHsE6Is+I7oDaDW5pGtERf9nmaCLgvtRRFSr+ LS8Ah+1L6Ev3E1Er4GTQcWb8qZGdXaZHMT77JodYcZuV8scsg4F1v2L0ZxalGGvf/u7TwF KPkOkc5oTxZ+9fDvmwQWddfN7IQ5JxE= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-154-sTyQSQZkOdi-_XgnOZCk4Q-1; Wed, 25 Jun 2025 12:31:13 -0400 X-MC-Unique: sTyQSQZkOdi-_XgnOZCk4Q-1 X-Mimecast-MFC-AGG-ID: sTyQSQZkOdi-_XgnOZCk4Q_1750869072 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 79751180ABFC; Wed, 25 Jun 2025 16:31:09 +0000 (UTC) Received: from [10.22.80.93] (unknown [10.22.80.93]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9569F180045B; Wed, 25 Jun 2025 16:31:07 +0000 (UTC) Date: Wed, 25 Jun 2025 18:31:04 +0200 (CEST) From: Mikulas Patocka To: Damien Le Moal cc: linux-block@vger.kernel.org, Jens Axboe , dm-devel@lists.linux.dev, Mike Snitzer , Bart Van Assche Subject: Re: [PATCH v3 4/5] dm: dm-crypt: Do not partially accept write BIOs with zoned targets In-Reply-To: <20250625093327.548866-5-dlemoal@kernel.org> Message-ID: <574374f0-1ce5-ebc4-76ff-95c21b1ccc65@redhat.com> References: <20250625093327.548866-1-dlemoal@kernel.org> <20250625093327.548866-5-dlemoal@kernel.org> Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On Wed, 25 Jun 2025, Damien Le Moal wrote: > Read and write operations issued to a dm-crypt target may be split > according to the dm-crypt internal limits defined by the max_read_size > and max_write_size module parameters (default is 128 KB). The intent is > to improve processing time of large BIOs by splitting them into smaller > operations that can be parallelized on different CPUs. > > For zoned dm-crypt targets, this BIO splitting is still done but without > the parallel execution to ensure that the issuing order of write > operations to the underlying devices remains sequential. However, the > splitting itself causes other problems: > > 1) Since dm-crypt relies on the block layer zone write plugging to > handle zone append emulation using regular write operations, the > reminder of a split write BIO will always be plugged into the target > zone write plugged. Once the on-going write BIO finishes, this > reminder BIO is unplugged and issued from the zone write plug work. > If this reminder BIO itself needs to be split, the reminder will be > re-issued and plugged again, but that causes a call to a > blk_queue_enter(), which may block if a queue freeze operation was > initiated. This results in a deadlock as DM submission still holds > BIOs that the queue freeze side is waiting for. > > 2) dm-crypt relies on the emulation done by the block layer using > regular write operations for processing zone append operations. This > still requires to properly return the written sector as the BIO > sector of the original BIO. However, this can be done correctly only > and only if there is a single clone BIO used for processing the > original zone append operation issued by the user. If the size of a > zone append operation is larger than dm-crypt max_write_size, then > the orginal BIO will be split and processed as a chain of regular > write operations. Such chaining result in an incorrect written sector > being returned to the zone append issuer using the original BIO > sector. This in turn results in file system data corruptions using > xfs or btrfs. > > Fix this by modifying get_max_request_size() to always return the size > of the BIO to avoid it being split with dm_accpet_partial_bio() in > crypt_map(). get_max_request_size() is renamed to > get_max_request_sectors() to clarify the unit of the value returned > and its interface is changed to take a struct dm_target pointer and a > pointer to the struct bio being processed. In addition to this change, > to ensure that crypt_alloc_buffer() works correctly, set the dm-crypt > device max_hw_sectors limit to be at most > BIO_MAX_VECS << PAGE_SECTORS_SHIFT (1 MB with a 4KB page architecture). > This forces DM core to split write BIOs before passing them to > crypt_map(), and thus guaranteeing that dm-crypt can always accept an > entire write BIO without needing to split it. > > This change does not have any effect on the read path of dm-crypt. Read > operations can still be split and the BIO fragments processed in > parallel. There is also no impact on the performance of the write path > given that all zone write BIOs were already processed inline instead of > in parallel. > > This change also does not affect in any way regular dm-crypt block > devices. > > Fixes: f211268ed1f9 ("dm: Use the block layer zone append emulation") > Cc: stable@vger.kernel.org > Signed-off-by: Damien Le Moal Reviewed-by: Mikulas Patocka > --- > drivers/md/dm-crypt.c | 49 ++++++++++++++++++++++++++++++++++--------- > 1 file changed, 39 insertions(+), 10 deletions(-) > > diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c > index 17157c4216a5..4e80784d1734 100644 > --- a/drivers/md/dm-crypt.c > +++ b/drivers/md/dm-crypt.c > @@ -253,17 +253,35 @@ MODULE_PARM_DESC(max_read_size, "Maximum size of a read request"); > static unsigned int max_write_size = 0; > module_param(max_write_size, uint, 0644); > MODULE_PARM_DESC(max_write_size, "Maximum size of a write request"); > -static unsigned get_max_request_size(struct crypt_config *cc, bool wrt) > + > +static unsigned get_max_request_sectors(struct dm_target *ti, struct bio *bio) > { > + struct crypt_config *cc = ti->private; > unsigned val, sector_align; > - val = !wrt ? READ_ONCE(max_read_size) : READ_ONCE(max_write_size); > - if (likely(!val)) > - val = !wrt ? DM_CRYPT_DEFAULT_MAX_READ_SIZE : DM_CRYPT_DEFAULT_MAX_WRITE_SIZE; > - if (wrt || cc->used_tag_size) { > - if (unlikely(val > BIO_MAX_VECS << PAGE_SHIFT)) > - val = BIO_MAX_VECS << PAGE_SHIFT; > - } > - sector_align = max(bdev_logical_block_size(cc->dev->bdev), (unsigned)cc->sector_size); > + bool wrt = op_is_write(bio_op(bio)); > + > + if (wrt) { > + /* > + * For zoned devices, splitting write operations creates the > + * risk of deadlocking queue freeze operations with zone write > + * plugging BIO work when the reminder of a split BIO is > + * issued. So always allow the entire BIO to proceed. > + */ > + if (ti->emulate_zone_append) > + return bio_sectors(bio); > + > + val = min_not_zero(READ_ONCE(max_write_size), > + DM_CRYPT_DEFAULT_MAX_WRITE_SIZE); > + } else { > + val = min_not_zero(READ_ONCE(max_read_size), > + DM_CRYPT_DEFAULT_MAX_READ_SIZE); > + } > + > + if (wrt || cc->used_tag_size) > + val = min(val, BIO_MAX_VECS << PAGE_SHIFT); > + > + sector_align = max(bdev_logical_block_size(cc->dev->bdev), > + (unsigned)cc->sector_size); > val = round_down(val, sector_align); > if (unlikely(!val)) > val = sector_align; > @@ -3496,7 +3514,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio) > /* > * Check if bio is too large, split as needed. > */ > - max_sectors = get_max_request_size(cc, bio_data_dir(bio) == WRITE); > + max_sectors = get_max_request_sectors(ti, bio); > if (unlikely(bio_sectors(bio) > max_sectors)) > dm_accept_partial_bio(bio, max_sectors); > > @@ -3733,6 +3751,17 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits) > max_t(unsigned int, limits->physical_block_size, cc->sector_size); > limits->io_min = max_t(unsigned int, limits->io_min, cc->sector_size); > limits->dma_alignment = limits->logical_block_size - 1; > + > + /* > + * For zoned dm-crypt targets, there will be no internal splitting of > + * write BIOs to avoid exceeding BIO_MAX_VECS vectors per BIO. But > + * without respecting this limit, crypt_alloc_buffer() will trigger a > + * BUG(). Avoid this by forcing DM core to split write BIOs to this > + * limit. > + */ > + if (ti->emulate_zone_append) > + limits->max_hw_sectors = min(limits->max_hw_sectors, > + BIO_MAX_VECS << PAGE_SECTORS_SHIFT); > } > > static struct target_type crypt_target = { > -- > 2.49.0 >