Re: [PATCH 5.4 3/5] cifs: Introduce helpers for finding TCP connection

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Jun 26, 2023 at 11:34:44AM +0530, Shyam Prasad N wrote:
> On Sat, Jun 24, 2023 at 3:14 AM Rishabh Bhatnagar <risbhat@amazon.com> wrote:
> >
> > From: "Paulo Alcantara (SUSE)" <pc@cjr.nz>
> >
> > commit 345c1a4a9e09dc5842b7bbb6728a77910db69c52 upstream.
> >
> > Add helpers for finding TCP connections that are good candidates for
> > being used by DFS refresh worker.
> >
> > Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
> > Reviewed-by: Aurelien Aptel <aaptel@suse.com>
> > Signed-off-by: Steve French <stfrench@microsoft.com>
> > Signed-off-by: Rishabh Bhatnagar <risbhat@amazon.com>
> > ---
> >  fs/cifs/dfs_cache.c | 44 +++++++++++++++++++++++++++++++-------------
> >  1 file changed, 31 insertions(+), 13 deletions(-)
> >
> > diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
> > index 3ca65051b55c..31b3dc09e109 100644
> > --- a/fs/cifs/dfs_cache.c
> > +++ b/fs/cifs/dfs_cache.c
> > @@ -1305,6 +1305,30 @@ static char *get_dfs_root(const char *path)
> >         return npath;
> >  }
> >
> > +static inline void put_tcp_server(struct TCP_Server_Info *server)
> > +{
> > +       cifs_put_tcp_session(server, 0);
> > +}
> > +
> > +static struct TCP_Server_Info *get_tcp_server(struct smb_vol *vol)
> > +{
> > +       struct TCP_Server_Info *server;
> > +
> > +       server = cifs_find_tcp_session(vol);
> > +       if (IS_ERR_OR_NULL(server))
> > +               return NULL;
> > +
> > +       spin_lock(&GlobalMid_Lock);
> > +       if (server->tcpStatus != CifsGood) {
> > +               spin_unlock(&GlobalMid_Lock);
> > +               put_tcp_server(server);
> > +               return NULL;
> > +       }
> > +       spin_unlock(&GlobalMid_Lock);
> 
> We've moved away from using GlobalMid_Lock for anything other than MIDs.
> Please use server->srv_lock instead.

This is just a backport of a commit that showed up in the 5.6 release.
It's not new development.

thanks,

greg k-h