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 BB4062E8B83; Tue, 4 Aug 2026 18:01:20 +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=1785866481; cv=none; b=M3fvLe/rOE+TL/pnSncjdIfXRXejk0NtnqS25MdedrvI0P6JL3K48T7QtkMSsSpFvk1sQFaQ4SMSvbEe3TG8/vluFsW1KUL6RkAsph1dLlxR7dl0uIMQd6ZmcGJ8l3BxX3/lyNCczzXLazlxt+BpUwtl7aMckfIXiuDxdvgzsIE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785866481; c=relaxed/simple; bh=kQrul+/OUumM2Ya+kto/IwI4Np7MEBBN384/W5APbp0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EMZ87e5p0lrfTiAoJC/jz+hIejSAKA6jBLdNQahybUUpkF4/O/tK7+21Ff08siyIqBFybTUOmFex4kUkQdLxn1AgenT+lfEO3yhiQ0haPDxee9APm/ZZ/fhjrLEwTxGsrak+3PKBSZugnGIjTQiEIAI2FEjHtxHg39ZTPt2389k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nPfLkZ4u; 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="nPfLkZ4u" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id 549B71F000E9; Tue, 4 Aug 2026 18:01:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785866480; bh=RSCZdlfHoN3MNNuFMvr7QIlKkJ47f+bwICwB/uhDA4Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=nPfLkZ4uC1++e501adfyJeG5XBlMkJCQJrbKrS23H9Mjw345JgvBtH6qU3al983b7 Ethpm/m0+i9ddrwk/suuKrr1w54NrTCGTZuK0n1x2zemEqczgexKrTGp1KpHMRy/IY q4PMEa7clRn3ObuGZ1v0bNSxl4MXSWVW+j8cQSg8XUl55tPBsoRtx5tFZLUChR0lsB uEGgbK/BslSqTxu/Z0hPy0cn4f6eNbjiTKSLWFXgbbfWGq5RMHIFuFxJLdXm0WNBRl mWvDPFJw+ghJuVPnaKObQCenvV/8BLnSxIu3cQkzoBMECywmXCsbbdaF1FnFQw/io2 D/9zxSMt8KuTg== Date: Tue, 4 Aug 2026 11:01:19 -0700 From: "Darrick J. Wong" To: Andrey Albershteyn Cc: linux-xfs@vger.kernel.org, fsverity@lists.linux.dev, linux-fsdevel@vger.kernel.org, ebiggers@kernel.org, hch@lst.de, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-btrfs@vger.kernel.org Subject: Re: [PATCH v14 05/21] fsverity: improve flushing performance of fsverity_fill_zerohash Message-ID: <20260804180119.GJ3556460@frogsfrogsfrogs> References: <20260803200820.393203-1-aalbersh@kernel.org> <20260803200820.393203-6-aalbersh@kernel.org> Precedence: bulk X-Mailing-List: fsverity@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260803200820.393203-6-aalbersh@kernel.org> On Mon, Aug 03, 2026 at 10:07:55PM +0200, Andrey Albershteyn wrote: > The current version calls flush_dcache_folio(), in memcpy_to_folio(), to > flush whole folio on every digest (which is 128 for 4k) on the HIGHMEM > systems. Open code folio mapping and flushing to copy all digests at > once. Do we really have to care about HIGHMEM performance? I thought that was going soon anyway[1]. The code change *looks* reasonable but ugh it adds more complexity and how many 32-bit phones and servers are there? (For Andrey: Why is this bolted onto an XFS patchset? Nobody should run XFS on 32-bit at all these days.) --D [1] https://lwn.net/Articles/1051010/ > Reported-by: Eric Biggers > Link: https://lore.kernel.org/linux-fsdevel/20260401222717.GH2466@quark/ > Signed-off-by: Andrey Albershteyn > --- > fs/verity/pagecache.c | 28 ++++++++++++++++++++++++++-- > 1 file changed, 26 insertions(+), 2 deletions(-) > > diff --git a/fs/verity/pagecache.c b/fs/verity/pagecache.c > index 9d82e6b74ba1..911207dc0ef7 100644 > --- a/fs/verity/pagecache.c > +++ b/fs/verity/pagecache.c > @@ -68,14 +68,38 @@ EXPORT_SYMBOL_GPL(generic_readahead_merkle_tree); > void fsverity_fill_zerohash(struct folio *folio, size_t offset, size_t len, > struct fsverity_info *vi) > { > - size_t off = offset; > + size_t off; > > WARN_ON_ONCE(!IS_ALIGNED(offset, vi->tree_params.digest_size)); > WARN_ON_ONCE(!IS_ALIGNED(len, vi->tree_params.digest_size)); > +#ifdef CONFIG_HIGHMEM > + WARN_ON_ONCE(offset + len > folio_size(folio)); > > - for (; off < (offset + len); off += vi->tree_params.digest_size) > + do { > + void *vaddr = kmap_local_folio(folio, offset); > + void *to = vaddr; > + > + off = len; > + > + if (folio_test_partial_kmap(folio) && > + off > PAGE_SIZE - offset_in_page(offset)) > + off = PAGE_SIZE - offset_in_page(offset); > + for (; to < (vaddr + off); to += vi->tree_params.digest_size) > + memcpy(to, vi->tree_params.zero_digest, > + vi->tree_params.digest_size); > + kunmap_local(vaddr); > + > + offset += off; > + len -= off; > + } while (len > 0); > + > + flush_dcache_folio(folio); > +#else > + for (off = offset; off < (offset + len); > + off += vi->tree_params.digest_size) > memcpy_to_folio(folio, off, vi->tree_params.zero_digest, > vi->tree_params.digest_size); > +#endif > } > EXPORT_SYMBOL_GPL(fsverity_fill_zerohash); > > -- > 2.54.0 > >