[{"id":3680239,"web_url":"http://patchwork.ozlabs.org/comment/3680239/","msgid":"","list_archive_url":null,"date":"2026-04-22T06:34:01","subject":"Re: [PATCH v2] iomap: avoid memset iomap when iter is done","submitter":{"id":178,"url":"http://patchwork.ozlabs.org/api/people/178/","name":"Christoph Hellwig","email":"hch@infradead.org"},"content":"Looks good:\n\nReviewed-by: Christoph Hellwig ","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ext4@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256\n header.s=bombadil.20210309 header.b=YdA1fg7E;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=150.107.74.76; helo=mail.ozlabs.org;\n envelope-from=srs0=mzua=cv=vger.kernel.org=linux-ext4+bounces-15989-patchwork-incoming=ozlabs.org@ozlabs.org;\n receiver=patchwork.ozlabs.org)","gandalf.ozlabs.org;\n arc=pass smtp.remote-ip=172.234.253.10 arc.chain=subspace.kernel.org","gandalf.ozlabs.org;\n dmarc=pass (p=none dis=none) header.from=infradead.org","gandalf.ozlabs.org;\n\tdkim=pass (2048-bit key;\n secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256\n header.s=bombadil.20210309 header.b=YdA1fg7E;\n\tdkim-atps=neutral","gandalf.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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arc=none smtp.client-ip=198.137.202.133"],"DKIM-Signature":"v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed;\n\td=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version\n\t:References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:\n\tContent-Transfer-Encoding:Content-ID:Content-Description;\n\tbh=M7NmYC/Iylm9myghHwqILim55SAUt9QrM+UZYk0eJlw=; b=YdA1fg7E9F57Ys7OPdHPtrzdef\n\t2pdbekkVLYPo9LtmZXZggekEEIu+temlrAFnU0M1OpaxE7dRJ+3rGBQHKTpNEF6vaVIg04h1JM698\n\tJVT5c/G2oMkpNHnBLk6sZ4kVd2QthPgFSa0VpSKrb+qcmw/JNKRlibq9gwGsJYVBH5Mt7/nj93aX8\n\t0ZpISW+vJPwE/qzi8u4Ma1jXirDhSGxQC3Anik0614XUP9qDw5mmuhjJ/+yxLH5mQfYXuQYFQLBKc\n\thGGj+4C5kaINtigsIVQV1K90GzGqaa+H8L/bDXYC2CGMyWwX+rnlAgvydwH8CB3pvw/dVAldii0KV\n\t+lQtzhTQ==;","Date":"Tue, 21 Apr 2026 23:34:01 -0700","From":"Christoph Hellwig ","To":"Fengnan Chang ","Cc":"brauner@kernel.org, djwong@kernel.org, hch@infradead.org,\n\tlinux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,\n\tlinux-ext4@vger.kernel.org, lidiangang@bytedance.com,\n\tFengnan Chang ","Subject":"Re: [PATCH v2] iomap: avoid memset iomap when iter is done","Message-ID":"","References":"<20260420061630.62077-1-changfengnan@bytedance.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":"<20260420061630.62077-1-changfengnan@bytedance.com>","X-SRS-Rewrite":"SMTP reverse-path rewritten from by\n bombadil.infradead.org. See http://www.infradead.org/rpr.html","X-Spam-Status":"No, score=-1.2 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_PASS,\n\tHEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,\n\tSPF_PASS autolearn=disabled version=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org"}},{"id":3680487,"web_url":"http://patchwork.ozlabs.org/comment/3680487/","msgid":"","list_archive_url":null,"date":"2026-04-22T10:59:48","subject":"Re: [PATCH v2] iomap: avoid memset iomap when iter is done","submitter":{"id":13037,"url":"http://patchwork.ozlabs.org/api/people/13037/","name":"Brian Foster","email":"bfoster@redhat.com"},"content":"On Mon, Apr 20, 2026 at 02:16:30PM +0800, Fengnan Chang wrote:\n> When iomap_iter() finishes its iteration (returns <= 0), it is no longer\n> necessary to memset the entire iomap and srcmap structures.\n> \n> In high-IOPS scenarios (like 4k randread NVMe polling with io_uring),\n> where the majority of I/Os complete in a single extent map, this wasted\n> memory write bandwidth, as the caller will just discard the iterator.\n> Use this command to test:\n> taskset -c 30 ./t/io_uring -p1 -d512 -b4096 -s32 -c32 -F1 -B1 -R1 -X1\n> -n1 -P1 /mnt/testfile\n> IOPS improve about 5% on ext4 and XFS.\n> \n> However, we MUST still call iomap_iter_reset_iomap() to release the\n> folio_batch if IOMAP_F_FOLIO_BATCH is set, otherwise we leak page\n> references. Therefore, split the cleanup logic: always release the\n> folio_batch, but skip the memset() when ret <= 0.\n> \n> Signed-off-by: Fengnan Chang \n> ---\n\nReviewed-by: Brian Foster \n\n> fs/iomap/iter.c | 12 ++++++------\n> 1 file changed, 6 insertions(+), 6 deletions(-)\n> \n> diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c\n> index c04796f6e57f..e4a29829591a 100644\n> --- a/fs/iomap/iter.c\n> +++ b/fs/iomap/iter.c\n> @@ -6,17 +6,13 @@\n> #include \n> #include \"trace.h\"\n> \n> -static inline void iomap_iter_reset_iomap(struct iomap_iter *iter)\n> +static inline void iomap_iter_clean_fbatch(struct iomap_iter *iter)\n> {\n> \tif (iter->iomap.flags & IOMAP_F_FOLIO_BATCH) {\n> \t\tfolio_batch_release(iter->fbatch);\n> \t\tfolio_batch_reinit(iter->fbatch);\n> \t\titer->iomap.flags &= ~IOMAP_F_FOLIO_BATCH;\n> \t}\n> -\n> -\titer->status = 0;\n> -\tmemset(&iter->iomap, 0, sizeof(iter->iomap));\n> -\tmemset(&iter->srcmap, 0, sizeof(iter->srcmap));\n> }\n> \n> /* Advance the current iterator position and decrement the remaining length */\n> @@ -102,10 +98,14 @@ int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)\n> \t\tret = 0;\n> \telse\n> \t\tret = 1;\n> -\tiomap_iter_reset_iomap(iter);\n> +\tiomap_iter_clean_fbatch(iter);\n> +\titer->status = 0;\n> \tif (ret <= 0)\n> \t\treturn ret;\n> \n> +\tmemset(&iter->iomap, 0, sizeof(iter->iomap));\n> +\tmemset(&iter->srcmap, 0, sizeof(iter->srcmap));\n> +\n> begin:\n> \tret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,\n> \t\t\t &iter->iomap, &iter->srcmap);\n> -- \n> 2.39.5 (Apple Git-154)\n> \n>","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ext4@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=aLdIF0dU;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; 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arc=none smtp.client-ip=170.10.129.124"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n\ts=mimecast20190719; t=1776855597;\n\th=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n\t to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n\t in-reply-to:in-reply-to:references:references;\n\tbh=izjl8drGARtnJbDgV470Smw6Us4DYi0R0XZK5bmOh0M=;\n\tb=aLdIF0dU1jYYNI0aSt/22W69gVoq+Dplvx0NPn5jih0h15C4WWzZfeGu1wyUcUwJ9qTktP\n\tTIMPLdWcpCval/752Y3uqc4Jmj3c5H75lX8H5Q8GDcwjUpwzd4GP6a3d3pHYmfF+SoPb7j\n\t2VZzTgJd39909TNc37yoZiotuOz1QlU=","X-MC-Unique":"9KUf4_wFM6uiEpVsiOBTvw-1","X-Mimecast-MFC-AGG-ID":"9KUf4_wFM6uiEpVsiOBTvw_1776855593","Date":"Wed, 22 Apr 2026 06:59:48 -0400","From":"Brian Foster ","To":"Fengnan Chang ","Cc":"brauner@kernel.org, djwong@kernel.org, hch@infradead.org,\n\tlinux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,\n\tlinux-ext4@vger.kernel.org, lidiangang@bytedance.com,\n\tFengnan Chang ","Subject":"Re: [PATCH v2] iomap: avoid memset iomap when iter is done","Message-ID":"","References":"<20260420061630.62077-1-changfengnan@bytedance.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":"<20260420061630.62077-1-changfengnan@bytedance.com>","X-Scanned-By":"MIMEDefang 3.4.1 on 10.30.177.93","X-Spam-Status":"No, score=-1.2 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_PASS,\n\tHEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,\n\tSPF_PASS autolearn=disabled version=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org"}},{"id":3680621,"web_url":"http://patchwork.ozlabs.org/comment/3680621/","msgid":"<20260422-pflaster-verifizieren-382dd21880d0@brauner>","list_archive_url":null,"date":"2026-04-22T12:56:23","subject":"Re: [PATCH v2] iomap: avoid memset iomap when iter is done","submitter":{"id":82326,"url":"http://patchwork.ozlabs.org/api/people/82326/","name":"Christian Brauner","email":"brauner@kernel.org"},"content":"On Mon, 20 Apr 2026 14:16:30 +0800, Fengnan Chang wrote:\n> When iomap_iter() finishes its iteration (returns <= 0), it is no longer\n> necessary to memset the entire iomap and srcmap structures.\n> \n> In high-IOPS scenarios (like 4k randread NVMe polling with io_uring),\n> where the majority of I/Os complete in a single extent map, this wasted\n> memory write bandwidth, as the caller will just discard the iterator.\n> Use this command to test:\n> taskset -c 30 ./t/io_uring -p1 -d512 -b4096 -s32 -c32 -F1 -B1 -R1 -X1\n> -n1 -P1 /mnt/testfile\n> IOPS improve about 5% on ext4 and XFS.\n> \n> [...]\n\nApplied to the vfs-7.2.iomap branch of the vfs/vfs.git tree.\nPatches in the vfs-7.2.iomap branch should appear in linux-next soon.\n\nPlease report any outstanding bugs that were missed during review in a\nnew review to the original patch series allowing us to drop it.\n\nIt's encouraged to provide Acked-bys and Reviewed-bys even though the\npatch has now been applied. If possible patch trailers will be updated.\n\nNote that commit hashes shown below are subject to change due to rebase,\ntrailer updates or similar. If in doubt, please check the listed branch.\n\ntree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git\nbranch: master\n\n[1/1] iomap: avoid memset iomap when iter is done\n https://git.kernel.org/vfs/vfs/c/72fa5c7e5c81","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ext4@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=j82qdD6R;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=150.107.74.76; helo=mail.ozlabs.org;\n envelope-from=srs0=o20/=cv=vger.kernel.org=linux-ext4+bounces-15995-patchwork-incoming=ozlabs.org@ozlabs.org;\n receiver=patchwork.ozlabs.org)","gandalf.ozlabs.org;\n arc=pass smtp.remote-ip=104.64.211.4 arc.chain=subspace.kernel.org","gandalf.ozlabs.org;\n dmarc=pass (p=quarantine dis=none) header.from=kernel.org","gandalf.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=j82qdD6R;\n\tdkim-atps=neutral","gandalf.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=104.64.211.4; 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