From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2951878C76; Tue, 7 May 2024 21:11:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715116275; cv=none; b=BGmTTPVlqnJtFd6lYsnJ8iULVrgD19zbJjlIkCmQHtHFAaBIbj0NXjfPh0g+nTa8MZ3DHHUdqTytDeUPNjfSYHjku3rbcoyVi+FgWjWe/x69XAKGbVTlrIvUApBHqtXeYcWU0vdpoZnG67bKlY4UM8MMV90gHgdhMcwOKDkAtUA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715116275; c=relaxed/simple; bh=N17paVKsvnHlMoVYYbGAwSs5ZZJ5KRuS1vQScRvlcjg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oElh/bv3Bg518xCRLBYDdAjMTzCsJrHP5hyY8nSO1KdVCZlyASuPpcWAcb+Gvm6gkqlvmD0JbfsNoCm2e8zitAYgH3M8LN/wFbNjJ+8E3enHdKXKTE3HIL8BHsnWgw5a6QNlGhnvvdM231lJDZs1V7MFYrHpZm2WyRptwzjyqOg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WqdrQV8i; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WqdrQV8i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDFC5C2BBFC; Tue, 7 May 2024 21:11:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715116275; bh=N17paVKsvnHlMoVYYbGAwSs5ZZJ5KRuS1vQScRvlcjg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WqdrQV8insRznhS1yS8bFigi9YWERuZXqwTfAJ03UGBVCbiEEmW/kxgojAjC0agF7 HMb94pFs5CoDoZ4OixNdFLDT4aXt/g/0EFpsaCb982WWXI/RQ+2XLGeyV/Jq1o7H8p IXLNGPSLcUREpmxiQ6VUM93dnxbl0EIqo2DkVEqTms0gonZRfDCtyaTG2ZBy4vvvu7 ugrLjXODLxx89Znxlv9mxSG042NmyIkvzPsHih6e9KtNmtT5ewUfI7Kd/E2/GIZ1hK 64EN7mqB2nzqljWLrQLfB6gPBELzjcv7N49ukWuSPijpMdkWUsBcY7XKOfnJBSoetb 7xycCDWKc3VHg== Date: Tue, 7 May 2024 14:11:14 -0700 From: "Darrick J. Wong" To: "Ritesh Harjani (IBM)" Cc: linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, Matthew Wilcox , Ojaswin Mujoo , Jan Kara Subject: Re: [PATCHv2 2/2] iomap: Optimize iomap_read_folio Message-ID: <20240507211114.GU360919@frogsfrogsfrogs> References: <92ae9f3333c9a7e66214568d08f45664261c899c.1715067055.git.ritesh.list@gmail.com> Precedence: bulk X-Mailing-List: linux-ext4@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: <92ae9f3333c9a7e66214568d08f45664261c899c.1715067055.git.ritesh.list@gmail.com> On Tue, May 07, 2024 at 02:25:43PM +0530, Ritesh Harjani (IBM) wrote: > iomap_readpage_iter() handles "uptodate blocks" and "not uptodate blocks" > within a folio separately. This makes iomap_read_folio() to call into > ->iomap_begin() to request for extent mapping even though it might already > have an extent which is not fully processed. > This happens when we either have a large folio or with bs < ps. In these > cases we can have sub blocks which can be uptodate (say for e.g. due to > previous writes). With iomap_read_folio_iter(), this is handled more > efficiently by not calling ->iomap_begin() call until all the sub blocks > with the current folio are processed. > > iomap_read_folio_iter() handles multiple sub blocks within a given > folio but it's implementation logic is similar to how > iomap_readahead_iter() handles multiple folios within a single mapped > extent. Both of them iterate over a given range of folio/mapped extent > and call iomap_readpage_iter() for reading. > > Signed-off-by: Ritesh Harjani (IBM) > cc: Ojaswin Mujoo I like this improved changelog, it'e easier to understand why _read_folio_iter needs to exist. Reviewed-by: Darrick J. Wong --D > --- > fs/iomap/buffered-io.c | 20 +++++++++++++++++++- > 1 file changed, 19 insertions(+), 1 deletion(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 9f79c82d1f73..a9bd74ee7870 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -444,6 +444,24 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter, > return pos - orig_pos + plen; > } > > +static loff_t iomap_read_folio_iter(const struct iomap_iter *iter, > + struct iomap_readpage_ctx *ctx) > +{ > + struct folio *folio = ctx->cur_folio; > + size_t offset = offset_in_folio(folio, iter->pos); > + loff_t length = min_t(loff_t, folio_size(folio) - offset, > + iomap_length(iter)); > + loff_t done, ret; > + > + for (done = 0; done < length; done += ret) { > + ret = iomap_readpage_iter(iter, ctx, done); > + if (ret <= 0) > + return ret; > + } > + > + return done; > +} > + > int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) > { > struct iomap_iter iter = { > @@ -459,7 +477,7 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) > trace_iomap_readpage(iter.inode, 1); > > while ((ret = iomap_iter(&iter, ops)) > 0) > - iter.processed = iomap_readpage_iter(&iter, &ctx, 0); > + iter.processed = iomap_read_folio_iter(&iter, &ctx); > > if (ret < 0) > folio_set_error(folio); > -- > 2.44.0 > >