From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8565B2C026C; Mon, 31 Aug 2026 17:58:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788199118; cv=none; b=LYIbpxqjohCyt0kB2+EGn+7WJycLXCBoVxRAIsJhKZMtDsUlsviFbV9s7qvRWJliM/NJhwgLCUb1w6BGJnHVS0AoVP+tjjzKGPceg1PtUsvoDUuyZjsaC6ecCg+BIoC40yHM7eNg09/E6Y+mPgPigGdCx0cIuQy9s7ZT9mkczE0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788199118; c=relaxed/simple; bh=7hlcXfEhhOEchDnMJGW7aFwVI8RBhWAJpJ10JSj2xnk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lkLQr1KoD2kCWExYwQJZYLN0Ek0iXisL0DDXT5CX1VD/BcQ0KUXgXQnRD9CYjQ89L1yfgHV6aV1XfOrx/w0KUi6WP8G4j5o+rwb7+puN1RWbPmgsMImLzHUdDNa//ilkE67PD4cWH4L4YzJJimyk8kUdodhglQFxH/5x9HuzSjo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LxZlOXP3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LxZlOXP3" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id CBEF91F000E9; Mon, 31 Aug 2026 17:58:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788199116; bh=cgOW/XAgWzpbch2/xR0SNsNGS6YvhUERcwE/ga9MS8k=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=LxZlOXP3l2I7Y6P7owGfNxt06f1epr/NcirlKP0iqJl0JdhJASH9VYd1zW5YbKiIj bqF7lObPAcfC4cmOv3BYtdZurQltJEx3IAZ0NU7n0v8Lu7KEcNMXxJwN1vcc172lzC z/OpJdVPrRnAl1otPp7jSdmDbd5OrImPviHAWVMFi54fXxzzPDn3ekqNQfSOieW4bz Au5nRPZFG4c/kUwn+djgOF2OAYvO9T3q73DQveiToD1tyFqWT5w65aeHbWAeQXjZ4P MLTKCTBqDCOFUeZitlaCn/hULZIwGJ1D/W4guBvO98ktWSUSonCZvKHd7HXgFY/5gU j1tURceGMDIKw== Date: Mon, 31 Aug 2026 10:58:36 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: Jens Axboe , Christian Brauner , Carlos Maiolino , Tal Zussman , Anuj Gupta , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 03/17] block: split bio_iov_iter_bounce_write Message-ID: <20260831175836.GH1933798@frogsfrogsfrogs> References: <20260831064010.2574896-1-hch@lst.de> <20260831064010.2574896-4-hch@lst.de> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260831064010.2574896-4-hch@lst.de> On Mon, Aug 31, 2026 at 09:39:51AM +0300, Christoph Hellwig wrote: > Factor out a bio_alloc_bounce_folios helper that we'll use for a > different take on read-side bounce buffering soon. > > For that make it and also bio_free_folios available to callers outside of > bio.c. > > Signed-off-by: Christoph Hellwig This looks like a simple split of one function into two, right? If so, then I'm ok with this; Reviewed-by: "Darrick J. Wong" --D > --- > block/bio.c | 58 ++++++++++++++++++++++++++------------------- > include/linux/bio.h | 2 ++ > 2 files changed, 35 insertions(+), 25 deletions(-) > > diff --git a/block/bio.c b/block/bio.c > index efd9483b8348..a87c33fe96ac 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -1353,7 +1353,7 @@ static struct folio *folio_alloc_greedy(gfp_t gfp, size_t *size, > return folio_alloc(gfp, get_order(*size)); > } > > -static void bio_free_folios(struct bio *bio) > +void bio_free_folios(struct bio *bio) > { > struct bio_vec *bv; > int i; > @@ -1366,11 +1366,8 @@ static void bio_free_folios(struct bio *bio) > } > } > > -static int bio_iov_iter_bounce_write(struct bio *bio, struct iov_iter *iter, > - size_t maxlen, size_t minsize) > +int bio_alloc_bounce_folios(struct bio *bio, size_t total_len, size_t minsize) > { > - size_t total_len = min(maxlen, iov_iter_count(iter)); > - > if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) > return -EINVAL; > if (WARN_ON_ONCE(bio->bi_iter.bi_size)) > @@ -1380,7 +1377,6 @@ static int bio_iov_iter_bounce_write(struct bio *bio, struct iov_iter *iter, > > do { > size_t this_len = min(total_len, SZ_1M); > - size_t copied; > struct folio *folio; > > if (this_len > minsize * 2) > @@ -1393,32 +1389,44 @@ static int bio_iov_iter_bounce_write(struct bio *bio, struct iov_iter *iter, > if (!folio) > break; > bio_add_folio_nofail(bio, folio, this_len, 0); > + total_len -= this_len; > + } while (total_len && bio->bi_vcnt < bio->bi_max_vecs); > + > + if (!bio->bi_iter.bi_size) > + return -ENOMEM; > + return 0; > +} > + > +static int bio_iov_iter_bounce_write(struct bio *bio, struct iov_iter *iter, > + size_t maxlen, size_t minsize) > +{ > + size_t total_len = min(maxlen, iov_iter_count(iter)); > + size_t total_copied = 0; > + struct bio_vec *bv; > + int i, error; > + > + error = bio_alloc_bounce_folios(bio, total_len, minsize); > + if (error) > + return error; > + > + bio_for_each_bvec_all(bv, bio, i) { > + struct folio *folio = page_folio(bv->bv_page); > + size_t copied; > > if (iter->nofault) > - copied = copy_folio_from_iter_atomic(folio, 0, this_len, > - iter); > + copied = copy_folio_from_iter_atomic(folio, 0, > + bv->bv_len, iter); > else > - copied = copy_folio_from_iter(folio, 0, this_len, iter); > - if (copied < this_len) { > - /* > - * Need to revert the iov iter for all bytes we have > - * copied. > - * > - * However the bio size differs from the real copied > - * bytes as @this_len is queued but only advanced > - * less than that. > - * Need to compensate that for the revert. > - */ > - iov_iter_revert(iter, bio->bi_iter.bi_size - this_len + > - copied); > + copied = copy_folio_from_iter(folio, 0, bv->bv_len, > + iter); > + total_copied += copied; > + if (copied < bv->bv_len) { > + iov_iter_revert(iter, total_copied); > bio_free_folios(bio); > return -EFAULT; > } > - total_len -= this_len; > - } while (total_len && bio->bi_vcnt < bio->bi_max_vecs); > + } > > - if (!bio->bi_iter.bi_size) > - return -ENOMEM; > return bio_iov_iter_align_down(bio, iter, > &bio->bi_io_vec[bio->bi_vcnt - 1], minsize - 1); > } > diff --git a/include/linux/bio.h b/include/linux/bio.h > index 0070be355181..584b6abf6baf 100644 > --- a/include/linux/bio.h > +++ b/include/linux/bio.h > @@ -527,6 +527,8 @@ extern void bio_check_pages_dirty(struct bio *bio); > int bio_iov_iter_bounce(struct bio *bio, struct iov_iter *iter, size_t maxlen, > size_t minsize); > void bio_iov_iter_unbounce(struct bio *bio, bool is_error, bool mark_dirty); > +int bio_alloc_bounce_folios(struct bio *bio, size_t total_len, size_t minsize); > +void bio_free_folios(struct bio *bio); > > extern void bio_copy_data(struct bio *dst, struct bio *src); > extern void bio_free_pages(struct bio *bio); > -- > 2.53.0 > >