RE: [Patch v5 19/21] CIFS: SMBD: Read correct returned data length for RDMA write (SMB read) I/O

[Long Li]

> -----Original Message-----
> From: Pavel Shilovsky [mailto:piastryyy@xxxxxxxxx]
> Sent: Wednesday, November 1, 2017 9:50 AM
> To: Long Li <longli@xxxxxxxxxxxxx>
> Cc: Steve French <sfrench@xxxxxxxxx>; linux-cifs <linux-
> cifs@xxxxxxxxxxxxxxx>; samba-technical <samba-technical@xxxxxxxxxxxxxxx>;
> Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; linux-
> rdma@xxxxxxxxxxxxxxx; Tom Talpey <ttalpey@xxxxxxxxxxxxx>; Matthew
> Wilcox <mawilcox@xxxxxxxxxxxxx>; Stephen Hemminger
> <sthemmin@xxxxxxxxxxxxx>; Long Li <longli@xxxxxxxxxxxxx>
> Subject: Re: [Patch v5 19/21] CIFS: SMBD: Read correct returned data length
> for RDMA write (SMB read) I/O
> 
> 2017-10-18 16:09 GMT-07:00 Long Li <longli@xxxxxxxxxxxxxxxxxxxxxx>:
> > From: Long Li <longli@xxxxxxxxxxxxx>
> >
> > This patch is for preparing upper layer doing SMB read via RDMA write.
> >
> > When RDMA write is used for SMB read, the returned data length is in
> > DataRemaining in the response packet. Reading it properly by adding a
> > parameter to specifiy where the returned data length is.
> >
> > Add the defition for memory registration to wdata and return the
> > correct length based on if RDMA write is used.
> >
> > Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
> > ---
> >  fs/cifs/cifsglob.h | 13 +++++++++++--  fs/cifs/cifssmb.c  |  7
> > ++++++-  fs/cifs/smb1ops.c  |  6 +++++-  fs/cifs/smb2ops.c  | 12
> > ++++++++++--
> >  4 files changed, 32 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index
> > 2ae7d02..ddf83d8 100644
> > --- a/fs/cifs/cifsglob.h
> > +++ b/fs/cifs/cifsglob.h
> > @@ -228,8 +228,14 @@ struct smb_version_operations {
> >         __u64 (*get_next_mid)(struct TCP_Server_Info *);
> >         /* data offset from read response message */
> >         unsigned int (*read_data_offset)(char *);
> > -       /* data length from read response message */
> > -       unsigned int (*read_data_length)(char *);
> > +       /*
> > +        * Data length from read response message
> > +        * When in_remaining is true, the returned data length is in
> > +        * message field DataRemaining for out-of-band data read (e.g
> through
> > +        * Memory Registration RDMA write in SMBD).
> > +        * Otherwise, the returned data length is in message field DataLength.
> > +        */
> > +       unsigned int (*read_data_length)(char *, bool in_remaining);
> >         /* map smb to linux error */
> >         int (*map_error)(char *, bool);
> >         /* find mid corresponding to the response message */ @@
> > -1148,6 +1154,9 @@ struct cifs_readdata {
> >                                 struct cifs_readdata *rdata,
> >                                 struct iov_iter *iter);
> >         struct kvec                     iov[2];
> > +#ifdef CONFIG_CIFS_SMB_DIRECT
> > +       struct smbd_mr                  *mr;
> > +#endif
> >         unsigned int                    pagesz;
> >         unsigned int                    tailsz;
> >         unsigned int                    credits;
> > diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index
> > 08ff56a..a343db4 100644
> > --- a/fs/cifs/cifssmb.c
> > +++ b/fs/cifs/cifssmb.c
> > @@ -1533,8 +1533,13 @@ cifs_readv_receive(struct TCP_Server_Info
> *server, struct mid_q_entry *mid)
> >                  rdata->iov[0].iov_base, server->total_read);
> >
> >         /* how much data is in the response? */
> > -       data_len = server->ops->read_data_length(buf);
> > +#ifdef CONFIG_CIFS_SMB_DIRECT
> > +       data_len = server->ops->read_data_length(buf, rdata->mr);
> > +       if (!rdata->mr && (data_offset + data_len > buflen)) { #else
> > +       data_len = server->ops->read_data_length(buf, false);
> >         if (data_offset + data_len > buflen) {
> > +#endif
> >                 /* data_len is corrupt -- discard frame */
> >                 rdata->result = -EIO;
> >                 return cifs_readv_discard(server, mid); diff --git
> > a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c index a723df3..b718bb8 100644
> > --- a/fs/cifs/smb1ops.c
> > +++ b/fs/cifs/smb1ops.c
> > @@ -87,9 +87,13 @@ cifs_read_data_offset(char *buf)  }
> >
> >  static unsigned int
> > -cifs_read_data_length(char *buf)
> > +cifs_read_data_length(char *buf, bool in_remaining)
> >  {
> >         READ_RSP *rsp = (READ_RSP *)buf;
> > +       if (in_remaining) {
> > +               cifs_dbg(VFS, "Invalid SMB1 calling path, check
> > + code\n");
> 
> I would suggest to do WARN_ON(1) instead.

I will make the change.

> 
> > +               return 0;
> > +       }
> >         return (le16_to_cpu(rsp->DataLengthHigh) << 16) +
> >                le16_to_cpu(rsp->DataLength);  }
> 
> 
> --
> Best regards,
> Pavel Shilovsky