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 25C2474C14; Tue, 10 Mar 2026 00:54:32 +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=1773104073; cv=none; b=eQSKJ7mXptj9/jvxlOCuDL41o8IBc4p9Zl9ZqXiSls3m3ZeoMOks7PMTbp07X+FTsSWjPqIX0ys8G/riWR/ferFBd1zFy4hfBWI6QCtsKsl4wxnpUXpiKPNmNOGianwOH6L7xWSZdWNJL5SirQ5wV6TTpCJ7F5s9zWIGx1Q9w1A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773104073; c=relaxed/simple; bh=dD+yDAtPqSGN+bF1VISeh1X1ceJWh7z9IlEn5rSOH7s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tdom8ysHvdEwtFmPu3MfCCS6fvKrYgYJqY8vKPv0Fttz5ZsdPX3XPVNtcQmS+7RUeImPFA96dJ4goF0eXtxJRxPYxZPvpZNrLKPWJr8U+l9VYNNOmllf+4ig6vN2gRGfH7e4GfNQ3xO+JAf1Hx+uWeAkbDsnLRgUKm3oV7L1LXI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=de78d+Mn; 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="de78d+Mn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6D34C4CEF7; Tue, 10 Mar 2026 00:54:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773104072; bh=dD+yDAtPqSGN+bF1VISeh1X1ceJWh7z9IlEn5rSOH7s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=de78d+MnaW8U0E7l3cvBN4U2h6z25ueH/JD+bLWjeJ5i8/COdlU9RMWIwQ2vMl1eG UqdGxK760OqIVcJVwqj/YSJ3Qs7eHh2XvSxZmK9hgeCc/Iw9TSmalgWOLBP73Kk4Hq scbpdIcB5PHMsLzcajK9DZzyZ8mqiRijXbDL/TqNxGOTU5BKqZD1GoWsx6i4PS7wrR OOhFjlM/7/NMuM/NV72zht48rjUKr/l7/GN47nV+OYvmZB9YMo0dXI10g6+NluLzmI WEwl/XIuXdSd1a1Mqr5otnqUaTGRFonWqTxl+Lf2HC6AgKi2W7Y1SyWdyX8IZ3SOg9 pN546PuLivhWw== Date: Mon, 9 Mar 2026 17:54:32 -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 v4 07/25] iomap: introduce IOMAP_F_FSVERITY and teach writeback to handle fsverity Message-ID: <20260310005432.GZ6033@frogsfrogsfrogs> References: <20260309192355.176980-1-aalbersh@kernel.org> <20260309192355.176980-8-aalbersh@kernel.org> 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: <20260309192355.176980-8-aalbersh@kernel.org> On Mon, Mar 09, 2026 at 08:23:22PM +0100, Andrey Albershteyn wrote: > This flag indicates that I/O is for fsverity metadata. > > In the write path skip i_size check and i_size updates as metadata is > past EOF. In writeback don't update i_size and continue writeback if > even folio is beyond EOF. In read path don't zero fsverity folios, again > they are past EOF. > > The iomap_block_needs_zeroing() is also called from write path. For > folios of larger order we don't want to zero out pages in the folio as > these could contain other merkle tree blocks. For fsverity, filesystem > will request to read PAGE_SIZE memory regions. For data folios, iomap > will zero the rest of the folio for anything which is beyond EOF. We > don't want this for fsverity folios. > > Signed-off-by: Andrey Albershteyn This feels like a reasonable means to implement post-EOF data stashing for fsverity having gone through many other merkle tree IO path designs and discarded them all. :/ Reviewed-by: "Darrick J. Wong" Hey, at least some day we might get fscrypt+fsverity on xfs for free. --D > --- > fs/iomap/buffered-io.c | 34 +++++++++++++++++++++++++--------- > fs/iomap/trace.h | 3 ++- > include/linux/iomap.h | 5 +++++ > 3 files changed, 32 insertions(+), 10 deletions(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 51a58a0bfe6c..530794dcdd91 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -344,9 +344,16 @@ static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter, > { > const struct iomap *srcmap = iomap_iter_srcmap(iter); > > - return srcmap->type != IOMAP_MAPPED || > - (srcmap->flags & IOMAP_F_NEW) || > - pos >= i_size_read(iter->inode); > + if (srcmap->type != IOMAP_MAPPED) > + return true; > + > + if (srcmap->flags & IOMAP_F_NEW) > + return true; > + > + if (srcmap->flags & IOMAP_F_FSVERITY) > + return false; > + > + return pos >= i_size_read(iter->inode); > } > > /** > @@ -1152,13 +1159,14 @@ static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i, > * unlock and release the folio. > */ > old_size = iter->inode->i_size; > - if (pos + written > old_size) { > + if (pos + written > old_size && > + !(iter->iomap.flags & IOMAP_F_FSVERITY)) { > i_size_write(iter->inode, pos + written); > iter->iomap.flags |= IOMAP_F_SIZE_CHANGED; > } > __iomap_put_folio(iter, write_ops, written, folio); > > - if (old_size < pos) > + if (old_size < pos && !(iter->iomap.flags & IOMAP_F_FSVERITY)) > pagecache_isize_extended(iter->inode, old_size, pos); > > cond_resched(); > @@ -1786,13 +1794,21 @@ static int iomap_writeback_range(struct iomap_writepage_ctx *wpc, > * Check interaction of the folio with the file end. > * > * If the folio is entirely beyond i_size, return false. If it straddles > - * i_size, adjust end_pos and zero all data beyond i_size. > + * i_size, adjust end_pos and zero all data beyond i_size. Don't skip fsverity > + * folios as those are beyond i_size. > */ > -static bool iomap_writeback_handle_eof(struct folio *folio, struct inode *inode, > - u64 *end_pos) > +static bool iomap_writeback_handle_eof(struct folio *folio, > + struct iomap_writepage_ctx *wpc, > + u64 *end_pos) > { > + struct inode *inode = wpc->inode; > u64 isize = i_size_read(inode); > > + if (wpc->iomap.flags & IOMAP_F_FSVERITY) { > + WARN_ON_ONCE(folio_pos(folio) < isize); > + return true; > + } > + > if (*end_pos > isize) { > size_t poff = offset_in_folio(folio, isize); > pgoff_t end_index = isize >> PAGE_SHIFT; > @@ -1858,7 +1874,7 @@ int iomap_writeback_folio(struct iomap_writepage_ctx *wpc, struct folio *folio) > > trace_iomap_writeback_folio(inode, pos, folio_size(folio)); > > - if (!iomap_writeback_handle_eof(folio, inode, &end_pos)) > + if (!iomap_writeback_handle_eof(folio, wpc, &end_pos)) > return 0; > WARN_ON_ONCE(end_pos <= pos); > > diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h > index 532787277b16..5252051cc137 100644 > --- a/fs/iomap/trace.h > +++ b/fs/iomap/trace.h > @@ -118,7 +118,8 @@ DEFINE_RANGE_EVENT(iomap_zero_iter); > { IOMAP_F_ATOMIC_BIO, "ATOMIC_BIO" }, \ > { IOMAP_F_PRIVATE, "PRIVATE" }, \ > { IOMAP_F_SIZE_CHANGED, "SIZE_CHANGED" }, \ > - { IOMAP_F_STALE, "STALE" } > + { IOMAP_F_STALE, "STALE" }, \ > + { IOMAP_F_FSVERITY, "FSVERITY" } > > > #define IOMAP_DIO_STRINGS \ > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 531f9ebdeeae..dc39837b0d45 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -87,6 +87,11 @@ struct vm_fault; > #define IOMAP_F_INTEGRITY 0 > #endif /* CONFIG_BLK_DEV_INTEGRITY */ > > +/* > + * IO happens beyond inode EOF, fsverity metadata is stored there > + */ > +#define IOMAP_F_FSVERITY (1U << 10) > + > /* > * Flag reserved for file system specific usage > */ > -- > 2.51.2 > >