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 099E3145B06; Mon, 8 Jul 2024 17:56:33 +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=1720461393; cv=none; b=aPdJjiOPMVjnyuYdkmcyPH4WOwBRR6Tll4x1Q7o0UU28HZtfCtOghTXV+q2EVicWQ4XEcp0BjKdCQdVhTbyJ6VjNdN+7r1jtHrf4NvdXfTgzKxvzF6CDCOTJmEVTteQbMdZzDHmuDadEnpPT2X/PRp6vo3uhJgTjV2yGlwry8rM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720461393; c=relaxed/simple; bh=ldSMonw09uowixZAG1w7HeV2XNqsw5Kv87tLzoOwdXQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DaCPu8VkHqSyiPKxyu29MVvXH3Ppdwxs0Jaaq5m5Y6aOi6laJDExQLXvoXQyMLvJqNeSa4APmek6FXqZHrkQzq4+iBXMkMJp8vHWYhsGOnDbw+58nCQbt/cF949Mi4E8z4/CgYe1GqwGg09acY7BlQY8iL7Gg/c1FCGTXrm3JLA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gJv9ohke; 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="gJv9ohke" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB550C116B1; Mon, 8 Jul 2024 17:56:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720461392; bh=ldSMonw09uowixZAG1w7HeV2XNqsw5Kv87tLzoOwdXQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gJv9ohketiz/NpEQGPeC5qk/25+t69iW3iLJwpGL/37k69xJDPLpEfAxXmEzGHnzU woca85oEUKtEpgCWuQmK6nVraDF+biAkOBoQxcS525F5qJJhtFBtXWN83HgtxkSymP AU5BJlEdrXd8mSSE9sLbg/y9OVSbUy97jZVHMHmGXVKqdw+Q10uz916PoiaRDQrF3n l4BBY1rU2u+JBGW7bT6a5IsmgQauUGSH/g6KsAnskUGQEBtlGJ/GCieaiJPSG1idlf WIKkZob0AkBEIkWwMj4SNbk4ULHYUVMolsas5qwUyuNgUr5hhnh13pZiAnO7IY1gJs 5ml8sQtFz2/qQ== Date: Mon, 8 Jul 2024 10:56:32 -0700 From: "Darrick J. Wong" To: "Pankaj Raghav (Samsung)" Cc: david@fromorbit.com, willy@infradead.org, chandan.babu@oracle.com, brauner@kernel.org, akpm@linux-foundation.org, yang@os.amperecomputing.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, john.g.garry@oracle.com, linux-fsdevel@vger.kernel.org, hare@suse.de, p.raghav@samsung.com, mcgrof@kernel.org, gost.dev@samsung.com, cl@os.amperecomputing.com, linux-xfs@vger.kernel.org, hch@lst.de, Zi Yan Subject: Re: [PATCH v9 06/10] iomap: fix iomap_dio_zero() for fs bs > system page size Message-ID: <20240708175632.GN612460@frogsfrogsfrogs> References: <20240704112320.82104-1-kernel@pankajraghav.com> <20240704112320.82104-7-kernel@pankajraghav.com> Precedence: bulk X-Mailing-List: linux-xfs@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: <20240704112320.82104-7-kernel@pankajraghav.com> On Thu, Jul 04, 2024 at 11:23:16AM +0000, Pankaj Raghav (Samsung) wrote: > From: Pankaj Raghav > > iomap_dio_zero() will pad a fs block with zeroes if the direct IO size > < fs block size. iomap_dio_zero() has an implicit assumption that fs block > size < page_size. This is true for most filesystems at the moment. > > If the block size > page size, this will send the contents of the page > next to zero page(as len > PAGE_SIZE) to the underlying block device, > causing FS corruption. > > iomap is a generic infrastructure and it should not make any assumptions > about the fs block size and the page size of the system. > > Signed-off-by: Pankaj Raghav > --- > fs/iomap/buffered-io.c | 4 ++-- > fs/iomap/direct-io.c | 45 ++++++++++++++++++++++++++++++++++++------ > 2 files changed, 41 insertions(+), 8 deletions(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index f420c53d86acc..d745f718bcde8 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -2007,10 +2007,10 @@ iomap_writepages(struct address_space *mapping, struct writeback_control *wbc, > } > EXPORT_SYMBOL_GPL(iomap_writepages); > > -static int __init iomap_init(void) > +static int __init iomap_buffered_init(void) > { > return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE), > offsetof(struct iomap_ioend, io_bio), > BIOSET_NEED_BVECS); > } > -fs_initcall(iomap_init); > +fs_initcall(iomap_buffered_init); > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index f3b43d223a46e..c02b266bba525 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -11,6 +11,7 @@ > #include > #include > #include > +#include > #include > #include "trace.h" > > @@ -27,6 +28,13 @@ > #define IOMAP_DIO_WRITE (1U << 30) > #define IOMAP_DIO_DIRTY (1U << 31) > > +/* > + * Used for sub block zeroing in iomap_dio_zero() > + */ > +#define IOMAP_ZERO_PAGE_SIZE (SZ_64K) > +#define IOMAP_ZERO_PAGE_ORDER (get_order(IOMAP_ZERO_PAGE_SIZE)) > +static struct page *zero_page; > + > struct iomap_dio { > struct kiocb *iocb; > const struct iomap_dio_ops *dops; > @@ -232,13 +240,20 @@ void iomap_dio_bio_end_io(struct bio *bio) > } > EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io); > > -static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, > +static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, > loff_t pos, unsigned len) > { > struct inode *inode = file_inode(dio->iocb->ki_filp); > - struct page *page = ZERO_PAGE(0); > struct bio *bio; > > + if (!len) > + return 0; > + /* > + * Max block size supported is 64k > + */ > + if (WARN_ON_ONCE(len > IOMAP_ZERO_PAGE_SIZE)) > + return -EINVAL; > + > bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE); > fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, > GFP_KERNEL); > @@ -246,8 +261,9 @@ static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, > bio->bi_private = dio; > bio->bi_end_io = iomap_dio_bio_end_io; > > - __bio_add_page(bio, page, len, 0); > + __bio_add_page(bio, zero_page, len, 0); > iomap_dio_submit_bio(iter, dio, bio, pos); > + return 0; > } > > /* > @@ -356,8 +372,10 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter, > if (need_zeroout) { > /* zero out from the start of the block to the write offset */ > pad = pos & (fs_block_size - 1); > - if (pad) > - iomap_dio_zero(iter, dio, pos - pad, pad); > + > + ret = iomap_dio_zero(iter, dio, pos - pad, pad); > + if (ret) > + goto out; > } > > /* > @@ -431,7 +449,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter, > /* zero out from the end of the write to the end of the block */ > pad = pos & (fs_block_size - 1); > if (pad) > - iomap_dio_zero(iter, dio, pos, fs_block_size - pad); > + ret = iomap_dio_zero(iter, dio, pos, > + fs_block_size - pad); > } > out: > /* Undo iter limitation to current extent */ > @@ -753,3 +772,17 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > return iomap_dio_complete(dio); > } > EXPORT_SYMBOL_GPL(iomap_dio_rw); > + > +static int __init iomap_dio_init(void) > +{ > + zero_page = alloc_pages(GFP_KERNEL | __GFP_ZERO, > + IOMAP_ZERO_PAGE_ORDER); > + > + if (!zero_page) > + return -ENOMEM; > + > + set_memory_ro((unsigned long)page_address(zero_page), > + 1U << IOMAP_ZERO_PAGE_ORDER); > + return 0; > +} > +fs_initcall(iomap_dio_init); This ^^^ could be refactored into a zeropage.ko module some day as a separate patch to amortize the cost of the 64k buffer that never goes away. This patch looks ok though, so: Reviewed-by: Darrick J. Wong --D > -- > 2.44.1 > >