linux-kernel - Re: [PATCH v8 4/7] fsdax: Add dax_iomap_cow_copy() for dax_iomap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20210902073215.GC13867@lst.de>
Date:   Thu, 2 Sep 2021 09:32:15 +0200
From:   Christoph Hellwig <hch@....de>
To:     Shiyang Ruan <ruansy.fnst@...itsu.com>
Cc:     djwong@...nel.org, hch@....de, linux-xfs@...r.kernel.org,
        dan.j.williams@...el.com, david@...morbit.com,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        nvdimm@...ts.linux.dev, rgoldwyn@...e.de, viro@...iv.linux.org.uk,
        willy@...radead.org, Ritesh Harjani <riteshh@...ux.ibm.com>
Subject: Re: [PATCH v8 4/7] fsdax: Add dax_iomap_cow_copy() for
 dax_iomap_zero

On Sun, Aug 29, 2021 at 08:25:14PM +0800, Shiyang Ruan wrote:
> Punch hole on a reflinked file needs dax_iomap_cow_copy() too.
> Otherwise, data in not aligned area will be not correct.  So, add the
> srcmap to dax_iomap_zero() and replace memset() as dax_iomap_cow_copy().
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
> Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com>
> Reviewed-by: Darrick J. Wong <djwong@...nel.org>
> ---
>  fs/dax.c               | 26 ++++++++++++++++----------
>  fs/iomap/buffered-io.c |  4 ++--
>  include/linux/dax.h    |  3 ++-
>  3 files changed, 20 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index f4acb79cb811..b294900e574e 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1209,7 +1209,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
>  }
>  #endif /* CONFIG_FS_DAX_PMD */
>  
> -s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
> +s64 dax_iomap_zero(loff_t pos, u64 length, const struct iomap *iomap,
> +		const struct iomap *srcmap)

We can in fact pass the iomap_iter here as well.  (probably as a prep
patch).

>  	if (page_aligned)
>  		rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
> -	else
> +	else {
>  		rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);

I'd clean this up a bit by doing:

	id = dax_read_lock();	
	if (page_aligned) {
		rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
		goto out;
	}

	// non aligned case here without extra indentation or checks