linux-kernel - Re: [PATCH 4/8] cifs: Fix creating NFS-style char/block devices

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Message-ID: <20240929005116.jojmzxymevmdyvsa@pali>
Date: Sun, 29 Sep 2024 02:51:16 +0200
From: Pali Rohár <pali@...nel.org>
To: Steve French <smfrench@...il.com>
Cc: Steve French <sfrench@...ba.org>, Paulo Alcantara <pc@...guebit.com>,
	Ronnie Sahlberg <ronniesahlberg@...il.com>,
	CIFS <linux-cifs@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/8] cifs: Fix creating NFS-style char/block devices

I guess that patch 3 can be dropped too as Paulo fixed it recently in:
https://git.samba.org/sfrench/?p=sfrench/cifs-2.6.git;a=commit;h=663f295e35594f4c2584fc68c28546b747b637cd

On Saturday 28 September 2024 19:47:52 Steve French wrote:
> Patch 3 may need to be rebased, iirc patch 3 didn't merge but 1 and 2 did
> 
> On Sat, Sep 28, 2024, 7:44 PM Pali Rohár <pali@...nel.org> wrote:
> 
> > Ops, sorry for that. I just let my work branch on v6.11-rc7 and here
> > this change was not yet. But it is funny that we have hit this problem
> > independently in nearly same time.
> >
> > On Saturday 28 September 2024 19:18:26 Steve French wrote:
> > > Looks like a duplicate of Paulo's earlier already merged patch, so
> > > will skip this one.  Reviewing the others in the series now.
> > >
> > > commit a9de67336a4aa3ff2e706ba023fb5f7ff681a954
> > > Author: Paulo Alcantara <pc@...guebit.com>
> > > Date:   Wed Sep 18 21:53:35 2024 -0300
> > >
> > >     smb: client: set correct device number on nfs reparse points
> > >
> > >     Fix major and minor numbers set on special files created with NFS
> > >     reparse points.
> > >
> > > On Sat, Sep 28, 2024 at 5:02 PM Pali Rohár <pali@...nel.org> wrote:
> > > >
> > > > Linux SMB client currently creates NFS-style char and block devices
> > with
> > > > swapped major and minor numbers.
> > > >
> > > > Per MS-FSCC 2.1.2.6 NFS_SPECFILE_CHR and NFS_SPECFILE_BLK DataBuffer's
> > > > field contains two 32-bit integers that represent major and minor
> > device
> > > > numbers.
> > > >
> > > > So the first one 32-bit integer in DataBuffer is major number and
> > second
> > > > one in DataBuffer is minor number. Microsoft Windows NFS server reads
> > them
> > > > in this order too.
> > > >
> > > > But Linux CIFS client creates new reparse point DataBuffer with minor
> > > > number first and major number second.
> > > >
> > > > Fix this problem in Linux SMB client and puts major and minor number in
> > > > the correct order into DataBuffer.
> > > >
> > > > This change fixes interoperability of char and block devices on Windows
> > > > share which is exported over both SMB and NFS protocols.
> > > >
> > > > Fixes: 102466f303ff ("smb: client: allow creating special files via
> > reparse points")
> > > > Signed-off-by: Pali Rohár <pali@...nel.org>
> > > > ---
> > > >  fs/smb/client/reparse.c | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
> > > > index 48c27581ec51..63984796721a 100644
> > > > --- a/fs/smb/client/reparse.c
> > > > +++ b/fs/smb/client/reparse.c
> > > > @@ -108,8 +108,8 @@ static int nfs_set_reparse_buf(struct
> > reparse_posix_data *buf,
> > > >         buf->InodeType = cpu_to_le64(type);
> > > >         buf->ReparseDataLength = cpu_to_le16(len + dlen -
> > > >                                              sizeof(struct
> > reparse_data_buffer));
> > > > -       *(__le64 *)buf->DataBuffer = cpu_to_le64(((u64)MAJOR(dev) <<
> > 32) |
> > > > -                                                MINOR(dev));
> > > > +       *(__le64 *)buf->DataBuffer = cpu_to_le64(((u64)MINOR(dev) <<
> > 32) |
> > > > +                                                MAJOR(dev));
> > > >         iov->iov_base = buf;
> > > >         iov->iov_len = len + dlen;
> > > >         return 0;
> > > > --
> > > > 2.20.1
> > > >
> > > >
> > >
> > >
> > > --
> > > Thanks,
> > >
> > > Steve
> >