From: Filipe Manana <fdmanana@gmail.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>,
Eric Sandeen <sandeen@redhat.com>,
linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-mm@kvack.org, linux-btrfs <linux-btrfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
ocfs2-devel@oss.oracle.com
Subject: Re: [PATCH 05/25] vfs: avoid problematic remapping requests into partial EOF block
Date: Fri, 12 Oct 2018 21:22:18 +0100 [thread overview]
Message-ID: <CAL3q7H7mLvCGpyitJhQ=To-aDvG9k9rxSVi2jSpcALQVj3myzg@mail.gmail.com> (raw)
In-Reply-To: <153923117420.5546.13317703807467393934.stgit@magnolia>
On Thu, Oct 11, 2018 at 5:13 AM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> A deduplication data corruption is exposed by fstests generic/505 on
> XFS.
(and btrfs)
Btw, the generic test I wrote was indeed numbered 505, however it was
never committed and there's now a generic/505 which has nothing to do
with deduplication.
So you should update the changelog to avoid confusion.
thanks
> It is caused by extending the block match range to include the
> partial EOF block, but then allowing unknown data beyond EOF to be
> considered a "match" to data in the destination file because the
> comparison is only made to the end of the source file. This corrupts the
> destination file when the source extent is shared with it.
>
> The VFS remapping prep functions only support whole block dedupe, but
> we still need to appear to support whole file dedupe correctly. Hence
> if the dedupe request includes the last block of the souce file, don't
> include it in the actual dedupe operation. If the rest of the range
> dedupes successfully, then reject the entire request. A subsequent
> patch will enable us to shorten dedupe requests correctly.
>
> When reflinking sub-file ranges, a data corruption can occur when the
> source file range includes a partial EOF block. This shares the unknown
> data beyond EOF into the second file at a position inside EOF, exposing
> stale data in the second file.
>
> If the reflink request includes the last block of the souce file, only
> proceed with the reflink operation if it lands at or past the
> destination file's current EOF. If it lands within the destination file
> EOF, reject the entire request with -EINVAL and make the caller go the
> hard way. A subsequent patch will enable us to shorten reflink requests
> correctly.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> fs/read_write.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index d6e8e242a15f..8498991e2f33 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1723,6 +1723,7 @@ int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
> {
> struct inode *inode_in = file_inode(file_in);
> struct inode *inode_out = file_inode(file_out);
> + u64 blkmask = i_blocksize(inode_in) - 1;
> bool same_inode = (inode_in == inode_out);
> int ret;
>
> @@ -1785,6 +1786,27 @@ int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
> return -EBADE;
> }
>
> + /* Are we doing a partial EOF block remapping of some kind? */
> + if (*len & blkmask) {
> + /*
> + * If the dedupe data matches, don't try to dedupe the partial
> + * EOF block.
> + *
> + * If the user is attempting to remap a partial EOF block and
> + * it's inside the destination EOF then reject it.
> + *
> + * We don't support shortening requests, so we can only reject
> + * them.
> + */
> + if (is_dedupe)
> + ret = -EBADE;
> + else if (pos_out + *len < i_size_read(inode_out))
> + ret = -EINVAL;
> +
> + if (ret)
> + return ret;
> + }
> +
> return 1;
> }
> EXPORT_SYMBOL(vfs_clone_file_prep);
>
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
next prev parent reply other threads:[~2018-10-12 20:22 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-11 4:12 [PATCH v3 00/25] fs: fixes for serious clone/dedupe problems Darrick J. Wong
2018-10-11 4:12 ` [PATCH 01/25] xfs: add a per-xfs trace_printk macro Darrick J. Wong
2018-10-11 13:39 ` Christoph Hellwig
2018-10-11 23:34 ` Darrick J. Wong
2018-10-11 4:12 ` [PATCH 02/25] vfs: vfs_clone_file_prep_inodes should return EINVAL for a clone from beyond EOF Darrick J. Wong
2018-10-11 13:40 ` Christoph Hellwig
2018-10-11 4:12 ` [PATCH 03/25] vfs: check file ranges before cloning files Darrick J. Wong
2018-10-11 13:42 ` Christoph Hellwig
2018-10-11 14:13 ` Amir Goldstein
2018-10-11 4:12 ` [PATCH 04/25] vfs: strengthen checking of file range inputs to generic_remap_checks Darrick J. Wong
2018-10-11 13:43 ` Christoph Hellwig
2018-10-11 4:12 ` [PATCH 05/25] vfs: avoid problematic remapping requests into partial EOF block Darrick J. Wong
2018-10-12 0:16 ` Dave Chinner
2018-10-12 16:07 ` Darrick J. Wong
2018-10-12 20:22 ` Filipe Manana [this message]
2018-10-15 0:31 ` Dave Chinner
2018-11-02 12:04 ` Filipe Manana
2018-11-02 17:42 ` Darrick J. Wong
2018-11-02 18:18 ` Filipe Manana
2018-11-02 19:05 ` Filipe Manana
2018-10-11 4:13 ` [PATCH 06/25] vfs: skip zero-length dedupe requests Darrick J. Wong
2018-10-11 4:13 ` [PATCH 07/25] vfs: combine the clone and dedupe into a single remap_file_range Darrick J. Wong
2018-10-11 4:13 ` [PATCH 08/25] vfs: rename vfs_clone_file_prep to be more descriptive Darrick J. Wong
2018-10-11 4:13 ` [PATCH 09/25] vfs: rename clone_verify_area to remap_verify_area Darrick J. Wong
2018-10-11 4:13 ` [PATCH 10/25] vfs: create generic_remap_file_range_touch to update inode metadata Darrick J. Wong
2018-10-11 4:13 ` [PATCH 11/25] vfs: pass remap flags to generic_remap_file_range_prep Darrick J. Wong
2018-10-11 4:13 ` [PATCH 12/25] vfs: pass remap flags to generic_remap_checks Darrick J. Wong
2018-10-11 4:13 ` [PATCH 13/25] vfs: make remap_file_range functions take and return bytes completed Darrick J. Wong
2018-10-11 4:14 ` [PATCH 14/25] vfs: plumb RFR_* remap flags through the vfs clone functions Darrick J. Wong
2018-10-11 4:14 ` [PATCH 15/25] vfs: plumb RFR_* remap flags through the vfs dedupe functions Darrick J. Wong
2018-10-11 4:14 ` [PATCH 16/25] vfs: make remapping to source file eof more explicit Darrick J. Wong
2018-10-11 4:14 ` [PATCH 17/25] vfs: enable remap callers that can handle short operations Darrick J. Wong
2018-10-11 5:15 ` Amir Goldstein
2018-10-11 16:04 ` Darrick J. Wong
2018-10-11 16:05 ` [PATCH v2 " Darrick J. Wong
2018-10-11 4:14 ` [PATCH 18/25] vfs: hide file range comparison function Darrick J. Wong
2018-10-11 4:14 ` [PATCH 19/25] vfs: implement opportunistic short dedupe Darrick J. Wong
2018-10-11 4:14 ` [PATCH 20/25] ocfs2: truncate page cache for clone destination file before remapping Darrick J. Wong
2018-10-11 4:14 ` [PATCH 21/25] ocfs2: fix pagecache truncation prior to reflink Darrick J. Wong
2018-10-11 4:15 ` [PATCH 22/25] ocfs2: support partial clone range and dedupe range Darrick J. Wong
2018-10-11 4:15 ` [PATCH 23/25] xfs: fix pagecache truncation prior to reflink Darrick J. Wong
2018-10-12 1:15 ` Dave Chinner
2018-10-11 4:15 ` [PATCH 24/25] xfs: support returning partial reflink results Darrick J. Wong
2018-10-12 1:22 ` Dave Chinner
2018-10-12 16:06 ` Darrick J. Wong
2018-10-11 4:15 ` [PATCH 25/25] xfs: remove redundant remap partial EOF block checks Darrick J. Wong
2018-10-12 1:22 ` Dave Chinner
2018-10-11 8:33 ` [PATCH v3 00/25] fs: fixes for serious clone/dedupe problems Amir Goldstein
2018-10-11 15:55 ` Darrick J. Wong
2018-10-13 0:05 [PATCH v4 " Darrick J. Wong
2018-10-13 0:06 ` [PATCH 05/25] vfs: avoid problematic remapping requests into partial EOF block Darrick J. Wong
2018-10-14 17:11 ` Christoph Hellwig
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