From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CF36C83F1D for ; Tue, 15 Jul 2025 05:20:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CD9506B0092; Tue, 15 Jul 2025 01:20:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CB0346B0093; Tue, 15 Jul 2025 01:20:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BC6E36B0095; Tue, 15 Jul 2025 01:20:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id AE9E06B0092 for ; Tue, 15 Jul 2025 01:20:14 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 2BBE758B0F for ; Tue, 15 Jul 2025 05:20:14 +0000 (UTC) X-FDA: 83665347948.21.DBD46B3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf14.hostedemail.com (Postfix) with ESMTP id 97DF4100005 for ; Tue, 15 Jul 2025 05:20:12 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Q5VIZ9u+; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of djwong@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=djwong@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752556812; a=rsa-sha256; cv=none; b=zOyofBtcq1kmlOPs1KLOO7huD0CzPtkjmU2WL9JRcSNseTTV6+tZHJqkAsW9mMQNFAlT04 61WoVuPT4GETRd5b1ljaXhA0H0n0/INwvk7hEE1X9tFNWQ0yzCeiKkmNBd1sSFjU6niLYo ewPcQVnoC3ii1quwB/HUP2QqEPxJYZo= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Q5VIZ9u+; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf14.hostedemail.com: domain of djwong@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=djwong@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1752556812; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=3e0kYLPD73zfqBP4AOOzZzCe8nyf8cZwubNHhF85e+U=; b=R+PiKXi5Yfj1kSQRBSkMK/nzQkLdUoxBh6mbueNV6wywb9TqENmFZgcJXmh7Yb8Rv6g5JJ f+bwnZDZaqmTWt1yz/OGqCR0ysKQtUNhRGWgot98/UIy4Kx10EfW7+5dKEo9w82Wv36k9b lMeHIQEAw2bpH4SXWUTfhDfF6CBZUzk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id EABDE60053; Tue, 15 Jul 2025 05:20:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90A4DC4CEE3; Tue, 15 Jul 2025 05:20:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752556811; bh=EUM3Bv+Y3HYOMRHJNG6hn45eJHccsRF1nJ4qkDSEuuw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Q5VIZ9u+L5P6mMTmOgiRE7K/UyoIGYM9fqi/9MEvDCSfJiAe5zuiZPJY5OluFuO12 IH5BlYOjWzaJVxHOEzE2+0ezKVoEh3U4xeg41m8oLa+X+LAdhdOvL6+5PghX+20EdG ThT2IWAyuSyHKY36m+lB93t7tzOCNbMJAbWm1TAuuujOCBKbjJ5nWdDJLvYWcDMq00 p1p6R47mzfiMpIQxVnJk6Bf3riDO0o8GMX0bCj1DhcJXNQzkM1hrWVKDqTBChtRBe9 CdXjPxonJsk0CHTN09EWQW6QXf/iFLoCd2CSXZAw4pslWEAOW8Pqr7r6wr8vKSmFd0 n8NSvaYzD/asA== Date: Mon, 14 Jul 2025 22:20:11 -0700 From: "Darrick J. Wong" To: Brian Foster Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, hch@infradead.org, willy@infradead.org Subject: Re: [PATCH v3 1/7] filemap: add helper to look up dirty folios in a range Message-ID: <20250715052011.GN2672049@frogsfrogsfrogs> References: <20250714204122.349582-1-bfoster@redhat.com> <20250714204122.349582-2-bfoster@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250714204122.349582-2-bfoster@redhat.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 97DF4100005 X-Stat-Signature: fiudmrqx6hxbcyjsrf7ip1zxcfw8ahik X-Rspam-User: X-HE-Tag: 1752556812-50275 X-HE-Meta: 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 9ewny0O4 gruYqE7Ngu2JQXGQL2IInQOC9hVEwrX4/Q38PXe5OlK22/oQRgximZfuXeFEq/nFkXE06IooJGPkAyry8uzAgCGqPubM4DSQHwZ5BLCE0OzwUKZNRq04sAMvTFyDjNBSHwpvAOH5FUGDZ9Mvzyha1Lpm3+slHHKhGzXTuk1oa1z6LASOghuHGiqv1GUwSAD+vS/OMqUuUT6N+7wASOgLtHUl8TeYo/+FhPkFswcv4d/V8aSD/t8EZ1rw/rWVFp2VmZfXeC1oGvsSukgvut2LpuHFHpUH6hmKtiFo56EWWT/OCCZE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 14, 2025 at 04:41:16PM -0400, Brian Foster wrote: > Add a new filemap_get_folios_dirty() helper to look up existing dirty > folios in a range and add them to a folio_batch. This is to support > optimization of certain iomap operations that only care about dirty > folios in a target range. For example, zero range only zeroes the subset > of dirty pages over unwritten mappings, seek hole/data may use similar > logic in the future, etc. > > Note that the helper is intended for use under internal fs locks. > Therefore it trylocks folios in order to filter out clean folios. > This loosely follows the logic from filemap_range_has_writeback(). > > Signed-off-by: Brian Foster > Reviewed-by: Christoph Hellwig This seems correct to me, though like hch said, I'd like to hear from willy. Reviewed-by: "Darrick J. Wong" --D > --- > include/linux/pagemap.h | 2 ++ > mm/filemap.c | 58 +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 60 insertions(+) > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index e63fbfbd5b0f..fb83ddf26621 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -941,6 +941,8 @@ unsigned filemap_get_folios_contig(struct address_space *mapping, > pgoff_t *start, pgoff_t end, struct folio_batch *fbatch); > unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start, > pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch); > +unsigned filemap_get_folios_dirty(struct address_space *mapping, > + pgoff_t *start, pgoff_t end, struct folio_batch *fbatch); > > /* > * Returns locked page at given index in given cache, creating it if needed. > diff --git a/mm/filemap.c b/mm/filemap.c > index bada249b9fb7..2171b7f689b0 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2334,6 +2334,64 @@ unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start, > } > EXPORT_SYMBOL(filemap_get_folios_tag); > > +/** > + * filemap_get_folios_dirty - Get a batch of dirty folios > + * @mapping: The address_space to search > + * @start: The starting folio index > + * @end: The final folio index (inclusive) > + * @fbatch: The batch to fill > + * > + * filemap_get_folios_dirty() works exactly like filemap_get_folios(), except > + * the returned folios are presumed to be dirty or undergoing writeback. Dirty > + * state is presumed because we don't block on folio lock nor want to miss > + * folios. Callers that need to can recheck state upon locking the folio. > + * > + * This may not return all dirty folios if the batch gets filled up. > + * > + * Return: The number of folios found. > + * Also update @start to be positioned for traversal of the next folio. > + */ > +unsigned filemap_get_folios_dirty(struct address_space *mapping, pgoff_t *start, > + pgoff_t end, struct folio_batch *fbatch) > +{ > + XA_STATE(xas, &mapping->i_pages, *start); > + struct folio *folio; > + > + rcu_read_lock(); > + while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) { > + if (xa_is_value(folio)) > + continue; > + if (folio_trylock(folio)) { > + bool clean = !folio_test_dirty(folio) && > + !folio_test_writeback(folio); > + folio_unlock(folio); > + if (clean) { > + folio_put(folio); > + continue; > + } > + } > + if (!folio_batch_add(fbatch, folio)) { > + unsigned long nr = folio_nr_pages(folio); > + *start = folio->index + nr; > + goto out; > + } > + } > + /* > + * We come here when there is no folio beyond @end. We take care to not > + * overflow the index @start as it confuses some of the callers. This > + * breaks the iteration when there is a folio at index -1 but that is > + * already broke anyway. > + */ > + if (end == (pgoff_t)-1) > + *start = (pgoff_t)-1; > + else > + *start = end + 1; > +out: > + rcu_read_unlock(); > + > + return folio_batch_count(fbatch); > +} > + > /* > * CD/DVDs are error prone. When a medium error occurs, the driver may fail > * a _large_ part of the i/o request. Imagine the worst scenario: > -- > 2.50.0 > >