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From: Olga Kornievskaia <aglo@umich.edu>
To: Luis Henriques <lhenriques@suse.de>
Cc: Amir Goldstein <amir73il@gmail.com>,
	Jeff Layton <jlayton@kernel.org>,
	Steve French <sfrench@samba.org>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Trond Myklebust <trond.myklebust@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Dave Chinner <dchinner@redhat.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Nicolas Boichat <drinkcat@chromium.org>,
	Ian Lance Taylor <iant@google.com>,
	Luis Lozano <llozano@chromium.org>,
	Andreas Dilger <adilger@dilger.ca>,
	Christoph Hellwig <hch@infradead.org>,
	ceph-devel <ceph-devel@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	CIFS <linux-cifs@vger.kernel.org>,
	samba-technical <samba-technical@lists.samba.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-nfs <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v8] vfs: fix copy_file_range regression in cross-fs copies
Date: Tue, 23 Feb 2021 20:00:54 -0500	[thread overview]
Message-ID: <CAN-5tyELMY7b7CKO-+an47ydq8r_4+SOyhuvdH0qE0-JmdZ44Q@mail.gmail.com> (raw)
In-Reply-To: <20210222102456.6692-1-lhenriques@suse.de>

On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote:
>
> A regression has been reported by Nicolas Boichat, found while using the
> copy_file_range syscall to copy a tracefs file.  Before commit
> 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the
> kernel would return -EXDEV to userspace when trying to copy a file across
> different filesystems.  After this commit, the syscall doesn't fail anymore
> and instead returns zero (zero bytes copied), as this file's content is
> generated on-the-fly and thus reports a size of zero.
>
> This patch restores some cross-filesystem copy restrictions that existed
> prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across
> devices").  Filesystems are still allowed to fall-back to the VFS
> generic_copy_file_range() implementation, but that has now to be done
> explicitly.
>
> nfsd is also modified to fall-back into generic_copy_file_range() in case
> vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV.
>
> Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices")
> Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/
> Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/
> Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/
> Reported-by: Nicolas Boichat <drinkcat@chromium.org>
> Signed-off-by: Luis Henriques <lhenriques@suse.de>

I tested v8 and I believe it works for NFS.

> ---
> Changes since v7
> - set 'ret' to '-EOPNOTSUPP' before the clone 'if' statement so that the
>   error returned is always related to the 'copy' operation
> Changes since v6
> - restored i_sb checks for the clone operation
> Changes since v5
> - check if ->copy_file_range is NULL before calling it
> Changes since v4
> - nfsd falls-back to generic_copy_file_range() only *if* it gets -EOPNOTSUPP
>   or -EXDEV.
> Changes since v3
> - dropped the COPY_FILE_SPLICE flag
> - kept the f_op's checks early in generic_copy_file_checks, implementing
>   Amir's suggestions
> - modified nfsd to use generic_copy_file_range()
> Changes since v2
> - do all the required checks earlier, in generic_copy_file_checks(),
>   adding new checks for ->remap_file_range
> - new COPY_FILE_SPLICE flag
> - don't remove filesystem's fallback to generic_copy_file_range()
> - updated commit changelog (and subject)
> Changes since v1 (after Amir review)
> - restored do_copy_file_range() helper
> - return -EOPNOTSUPP if fs doesn't implement CFR
> - updated commit description
>
>  fs/nfsd/vfs.c   |  8 +++++++-
>  fs/read_write.c | 49 ++++++++++++++++++++++++-------------------------
>  2 files changed, 31 insertions(+), 26 deletions(-)
>
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 04937e51de56..23dab0fa9087 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -568,6 +568,7 @@ __be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos,
>  ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
>                              u64 dst_pos, u64 count)
>  {
> +       ssize_t ret;
>
>         /*
>          * Limit copy to 4MB to prevent indefinitely blocking an nfsd
> @@ -578,7 +579,12 @@ ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
>          * limit like this and pipeline multiple COPY requests.
>          */
>         count = min_t(u64, count, 1 << 22);
> -       return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
> +       ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
> +
> +       if (ret == -EOPNOTSUPP || ret == -EXDEV)
> +               ret = generic_copy_file_range(src, src_pos, dst, dst_pos,
> +                                             count, 0);
> +       return ret;
>  }
>
>  __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 75f764b43418..5a26297fd410 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1388,28 +1388,6 @@ ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
>  }
>  EXPORT_SYMBOL(generic_copy_file_range);
>
> -static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in,
> -                                 struct file *file_out, loff_t pos_out,
> -                                 size_t len, unsigned int flags)
> -{
> -       /*
> -        * Although we now allow filesystems to handle cross sb copy, passing
> -        * a file of the wrong filesystem type to filesystem driver can result
> -        * in an attempt to dereference the wrong type of ->private_data, so
> -        * avoid doing that until we really have a good reason.  NFS defines
> -        * several different file_system_type structures, but they all end up
> -        * using the same ->copy_file_range() function pointer.
> -        */
> -       if (file_out->f_op->copy_file_range &&
> -           file_out->f_op->copy_file_range == file_in->f_op->copy_file_range)
> -               return file_out->f_op->copy_file_range(file_in, pos_in,
> -                                                      file_out, pos_out,
> -                                                      len, flags);
> -
> -       return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
> -                                      flags);
> -}
> -
>  /*
>   * Performs necessary checks before doing a file copy
>   *
> @@ -1427,6 +1405,25 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
>         loff_t size_in;
>         int ret;
>
> +       /*
> +        * Although we now allow filesystems to handle cross sb copy, passing
> +        * a file of the wrong filesystem type to filesystem driver can result
> +        * in an attempt to dereference the wrong type of ->private_data, so
> +        * avoid doing that until we really have a good reason.  NFS defines
> +        * several different file_system_type structures, but they all end up
> +        * using the same ->copy_file_range() function pointer.
> +        */
> +       if (file_out->f_op->copy_file_range) {
> +               if (file_in->f_op->copy_file_range !=
> +                   file_out->f_op->copy_file_range)
> +                       return -EXDEV;
> +       } else if (file_in->f_op->remap_file_range) {
> +               if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
> +                       return -EXDEV;
> +       } else {
> +                return -EOPNOTSUPP;
> +       }
> +
>         ret = generic_file_rw_checks(file_in, file_out);
>         if (ret)
>                 return ret;
> @@ -1495,6 +1492,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>
>         file_start_write(file_out);
>
> +       ret = -EOPNOTSUPP;
>         /*
>          * Try cloning first, this is supported by more file systems, and
>          * more efficient if both clone and copy are supported (e.g. NFS).
> @@ -1513,9 +1511,10 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>                 }
>         }
>
> -       ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len,
> -                               flags);
> -       WARN_ON_ONCE(ret == -EOPNOTSUPP);
> +       if (file_out->f_op->copy_file_range)
> +               ret = file_out->f_op->copy_file_range(file_in, pos_in,
> +                                                     file_out, pos_out,
> +                                                     len, flags);
>  done:
>         if (ret > 0) {
>                 fsnotify_access(file_in);

  parent reply	other threads:[~2021-02-24  1:10 UTC|newest]

Thread overview: 136+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-12  4:43 [PATCH 0/6] Add generated flag to filesystem struct to block copy_file_range Nicolas Boichat
2021-02-12  4:44 ` [PATCH 1/6] fs: Add flag to file_system_type to indicate content is generated Nicolas Boichat
2021-02-12  7:46   ` Greg KH
2021-02-12  8:20     ` Nicolas Boichat
2021-02-12  8:37       ` Greg KH
2021-02-12 15:33         ` Ian Lance Taylor
2021-02-12 15:45           ` Greg KH
2021-02-12 15:59             ` Ian Lance Taylor
2021-02-12 16:28               ` Greg KH
2021-02-12 20:22                 ` Ian Lance Taylor
2021-02-12 23:03             ` Dave Chinner
2021-02-12 23:07               ` Ian Lance Taylor
2021-02-12 23:27                 ` Dave Chinner
2021-02-12 23:54                   ` Darrick J. Wong
2021-02-15  0:38                     ` Dave Chinner
2021-02-15  1:12                       ` Ian Lance Taylor
2021-02-15  1:25                         ` Nicolas Boichat
2021-02-15  5:56                           ` Amir Goldstein
2021-02-15  8:30                           ` Greg KH
2021-02-12  8:22     ` Amir Goldstein
2021-02-12  8:39       ` Greg KH
2021-02-12 12:05         ` Luis Henriques
2021-02-12 12:18           ` Greg KH
2021-02-12 12:41             ` Luis Henriques
2021-02-12 14:11               ` Greg KH
2021-02-12 15:01                 ` Luis Henriques
2021-02-15  6:12               ` Amir Goldstein
2021-02-15 10:39                 ` Luis Henriques
2021-02-15 12:22                   ` Luis Henriques
2021-02-15 14:23                     ` Amir Goldstein
2021-02-15 14:51                       ` Luis Henriques
2021-02-15 15:43                       ` [PATCH v2] vfs: prevent copy_file_range to copy across devices Luis Henriques
2021-02-15 16:02                         ` Trond Myklebust
2021-02-16  0:25                           ` Steve French
2021-02-15 16:34                         ` Amir Goldstein
2021-02-15 16:53                           ` Trond Myklebust
2021-02-15 17:24                             ` Amir Goldstein
2021-02-15 18:57                               ` Trond Myklebust
2021-02-15 19:43                                 ` Amir Goldstein
2021-02-16 11:17                                   ` Luis Henriques
2021-02-16 11:28                                     ` gregkh
2021-02-16 12:01                                       ` Luis Henriques
2021-02-16 12:08                                         ` Greg KH
2021-02-16 13:51                                     ` Amir Goldstein
2021-02-16 16:42                                       ` Luis Henriques
2021-02-16 17:44                                         ` Amir Goldstein
2021-02-16 18:55                                           ` Luis Henriques
2021-02-16 19:20                                             ` Amir Goldstein
2021-02-16 19:27                                               ` Anna Schumaker
2021-02-16 19:31                                                 ` Steve French
2021-02-16 19:40                                                   ` Amir Goldstein
2021-02-16 21:15                                                     ` Steve French
2021-02-17  8:08                                                       ` Amir Goldstein
2021-02-17 17:26                                                         ` [PATCH v3] vfs: fix copy_file_range regression in cross-fs copies Luis Henriques
2021-02-17 20:47                                                           ` Amir Goldstein
2021-02-18  0:56                                                           ` Nicolas Boichat
2021-02-18  5:32                                                           ` Olga Kornievskaia
2021-02-18  6:47                                                             ` Amir Goldstein
2021-02-18 16:28                                                               ` Olga Kornievskaia
2021-02-18  7:43                                                           ` Christoph Hellwig
2021-02-18  0:50                                                         ` [PATCH v2] vfs: prevent copy_file_range to copy across devices Andreas Dilger
2021-02-18  7:34                                                           ` gregkh
2021-02-16 18:54                                       ` Andreas Dilger
2021-02-17  4:45                         ` Nicolas Boichat
2021-02-18  7:42                         ` Christoph Hellwig
2021-02-18  9:10                           ` Amir Goldstein
2021-02-18 10:29                             ` Luis Henriques
2021-02-18 12:15                               ` Luis Henriques
2021-02-18 12:49                                 ` Amir Goldstein
2021-02-18 14:36                                   ` [PATCH v4] vfs: fix copy_file_range regression in cross-fs copies Luis Henriques
2021-02-18 14:58                                     ` Amir Goldstein
2021-02-18 15:17                                       ` [PATCH v5] " Luis Henriques
2021-02-18 15:53                                         ` Amir Goldstein
2021-02-18 16:35                                           ` Luis Henriques
2021-02-18 17:18                                             ` [PATCH v6] " Luis Henriques
2021-02-19 21:18                                               ` Olga Kornievskaia
2021-02-19 21:52                                                 ` Amir Goldstein
2021-02-21 19:58                                                 ` [PATCH v7] " Luis Henriques
2021-02-22  3:00                                                   ` Nicolas Boichat
2021-02-22 10:24                                                   ` [PATCH v8] " Luis Henriques
2021-02-22 10:46                                                     ` Amir Goldstein
2021-02-22 16:25                                                     ` dai.ngo
2021-02-23 10:32                                                       ` Luis Henriques
2021-02-23 15:28                                                         ` Amir Goldstein
2021-02-23 15:29                                                         ` dai.ngo
2021-02-23 16:02                                                           ` dai.ngo
2021-02-23 16:47                                                             ` Amir Goldstein
2021-02-23 16:57                                                               ` dai.ngo
     [not found]                                                                 ` <e3eed18b-fc7e-e687-608b-7f662017329c@oracle.com>
2021-02-23 17:33                                                                   ` Amir Goldstein
2021-02-24  0:13                                                                     ` dai.ngo
2021-02-23 17:56                                                                 ` Luis Henriques
2021-02-23 17:13                                                             ` Olga Kornievskaia
2021-02-24  1:00                                                     ` Olga Kornievskaia [this message]
2021-02-24 10:23                                                       ` Luis Henriques
2021-02-24 10:44                                                         ` Nicolas Boichat
2021-04-09  5:23                                                           ` Nicolas Boichat
2021-04-09 13:39                                                             ` Luis Henriques
2021-04-09 13:50                                                               ` Amir Goldstein
2021-04-23  4:40                                                                 ` Nicolas Boichat
2021-05-03  8:54                                                                   ` Luis Henriques
2021-05-10  4:59                                                                     ` Amir Goldstein
2021-05-10  9:10                                                                       ` Luis Henriques
2021-02-24 14:23                                                     ` [PATCH] copy_file_range.2: Kernel v5.12 updates Luis Henriques
2021-02-24 16:10                                                       ` Amir Goldstein
2021-02-25 10:21                                                         ` Luis Henriques
2021-02-26 10:13                                                           ` Alejandro Colomar (man-pages)
2021-02-26 10:34                                                             ` Amir Goldstein
2021-02-26 11:15                                                               ` Alejandro Colomar (man-pages)
2021-02-26 13:59                                                                 ` Jeff Layton
2021-02-26 21:26                                                                   ` Alejandro Colomar (man-pages)
2021-02-26 22:18                                                         ` Alejandro Colomar (man-pages)
2021-02-27  5:41                                                           ` Amir Goldstein
2021-02-27 12:20                                                             ` Alejandro Colomar (man-pages)
2021-02-27 13:49                                                               ` [RFC v2] copy_file_range.2: Update cross-filesystem support for 5.12 Alejandro Colomar
2021-02-27 16:00                                                                 ` Amir Goldstein
2021-02-27 23:08                                                             ` [PATCH] copy_file_range.2: Kernel v5.12 updates Steve French
2021-02-28  7:35                                                               ` Amir Goldstein
2021-02-28 22:25                                                                 ` Steve French
2021-03-01  6:18                                                                   ` Amir Goldstein
2021-03-01 14:41                                                       ` [RFC v3] copy_file_range.2: Update cross-filesystem support for 5.12 Alejandro Colomar
2021-03-01 14:58                                                         ` Amir Goldstein
2021-03-04  9:38                                                       ` [RFC v4] " Alejandro Colomar
2021-03-04 17:13                                                         ` Darrick J. Wong
2021-03-04 18:24                                                           ` Alejandro Colomar (man-pages)
2021-03-04 23:50                                                             ` Darrick J. Wong
2021-02-24  7:15                                     ` [PATCH v4] vfs: fix copy_file_range regression in cross-fs copies Amir Goldstein
2021-02-24  8:30                                       ` Petr Vorel
2021-02-18 20:41                             ` [PATCH v2] vfs: prevent copy_file_range to copy across devices Steve French
2021-02-12 23:15       ` [PATCH 1/6] fs: Add flag to file_system_type to indicate content is generated Dave Chinner
2021-02-12  7:54   ` Amir Goldstein
2021-02-12  4:44 ` [PATCH 2/6] proc: Add FS_GENERATED_CONTENT to filesystem flags Nicolas Boichat
2021-02-12  4:44 ` [PATCH 6/6] vfs: Disallow copy_file_range on generated file systems Nicolas Boichat
2021-02-12  4:53   ` Darrick J. Wong
2021-02-12  4:59     ` Darrick J. Wong
2021-02-12  5:24       ` Nicolas Boichat
2021-02-14 23:09 ` [PATCH 0/6] Add generated flag to filesystem struct to block copy_file_range Al Viro

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