NT_STATUS_INSUFFICIENT_RESOURCES and retrying writes to Windows 10 servers

[ronnie sahlberg]

Reviewed-by: Ronnie Sahlberg <lsahlber at redhat.com>

On Tue, Jun 18, 2019 at 5:51 AM Steve French <smfrench at gmail.com> wrote:
>
> Attached is a patch with updated comments and cc:stable:
>
>
> On Sat, Jun 15, 2019 at 11:18 PM Steve French <smfrench at gmail.com> wrote:
> >
> > By default large file copy to Windows 10 can return MANY potentially
> > retryable errors on write (which we don't retry from the Linux cifs
> > client) which can cause cp to fail.
> >
> > It did look like my patch for the problem worked (see below).  Windows
> > 10 returns *A LOT* (about 1/3 of writes in some cases I tried) of
> > NT_STATUS_INSUFFICIENT_RESOURCES errors (presumably due to the
> > 'blocking operation credit' max of 64 in Windows 10 - see note 203 of
> > MS-SMB2).
> >
> > "<203> Section 3.3.4.2: Windows-based servers enforce a configurable
> > blocking operation credit,
> > which defaults to 64 on Windows Vista SP1, Windows 7, Windows 8,
> > Windows 8.1, and, Windows 10,
> > and defaults to 512 on Windows Server 2008, Windows Server 2008 R2,
> > Windows Server 2012 ..."
> >
> > This patch did seem to work around the problem, but perhaps we should
> > use far fewer credits when mounting to Windows 10 even though they are
> > giving us enough credits for more? Or change how we do writes to not
> > do synchronous writes? I haven't seen this problem to Windows 2016 or
> > 2019 but perhaps the explanation on note 203  is all we need to know
> > ... ie that clients can enforce a lower limit than 512
> >
> > ~/cifs-2.6/fs/cifs$ git diff -a
> > diff --git a/fs/cifs/smb2maperror.c b/fs/cifs/smb2maperror.c
> > index e32c264e3adb..82ade16c9501 100644
> > --- a/fs/cifs/smb2maperror.c
> > +++ b/fs/cifs/smb2maperror.c
> > @@ -457,7 +457,7 @@ static const struct status_to_posix_error
> > smb2_error_map_table[] = {
> >         {STATUS_FILE_INVALID, -EIO, "STATUS_FILE_INVALID"},
> >         {STATUS_ALLOTTED_SPACE_EXCEEDED, -EIO,
> >         "STATUS_ALLOTTED_SPACE_EXCEEDED"},
> > -       {STATUS_INSUFFICIENT_RESOURCES, -EREMOTEIO,
> > +       {STATUS_INSUFFICIENT_RESOURCES, -EAGAIN,
> >                                 "STATUS_INSUFFICIENT_RESOURCES"},
> >         {STATUS_DFS_EXIT_PATH_FOUND, -EIO, "STATUS_DFS_EXIT_PATH_FOUND"},
> >         {STATUS_DEVICE_DATA_ERROR, -EIO, "STATUS_DEVICE_DATA_ERROR"},
> >
> >
> > e.g. see the number of write errors in my 8GB copy in my test below
> >
> > # cat /proc/fs/cifs/Stats
> > Resources in use
> > CIFS Session: 1
> > Share (unique mount targets): 2
> > SMB Request/Response Buffer: 1 Pool size: 5
> > SMB Small Req/Resp Buffer: 1 Pool size: 30
> > Operations (MIDs): 0
> >
> > 0 session 0 share reconnects
> > Total vfs operations: 363 maximum at one time: 2
> >
> > 1) \\10.0.3.4\public-share
> > SMBs: 14879
> > Bytes read: 0  Bytes written: 8589934592
> > Open files: 2 total (local), 0 open on server
> > TreeConnects: 3 total 0 failed
> > TreeDisconnects: 0 total 0 failed
> > Creates: 12 total 0 failed
> > Closes: 10 total 0 failed
> > Flushes: 0 total 0 failed
> > Reads: 0 total 0 failed
> > Writes: 14838 total 5624 failed
> > ...
> >
> > Any thoughts?
> >
> > Any risk that we could run into places where EAGAIN would not be
> > handled (there are SMB3 commands other than read and write where
> > NT_STATUS_INSUFFICIENT_RESOURCES could be returned in theory)
> >
> > --
> > Thanks,
> >
> > Steve
>
>
>
> --
> Thanks,
>
> Steve