On Tue, 2023-08-01 at 18:51 -0400, Chuck Lever wrote: > On Wed, Aug 02, 2023 at 08:26:15AM +1000, NeilBrown wrote: > > On Tue, 01 Aug 2023, Jeff Layton wrote: > > > I noticed that xfstests generic/001 was failing against linux-next nfsd. > > > > > > The client would request a OPEN4_SHARE_ACCESS_WRITE open, and the server > > > would hand out a write delegation. The client would then try to use that > > > write delegation as the source stateid in a COPY or CLONE operation, and > > > the server would respond with NFS4ERR_STALE. > > > > > > The problem is that the struct file associated with the delegation does > > > not necessarily have read permissions. It's handing out a write > > > delegation on what is effectively an O_WRONLY open. RFC 8881 states: > > > > > > "An OPEN_DELEGATE_WRITE delegation allows the client to handle, on its > > > own, all opens." > > > > > > Given that the client didn't request any read permissions, and that nfsd > > > didn't check for any, it seems wrong to give out a write delegation. > > > > > > Only hand out a write delegation if we have a O_RDWR descriptor > > > available. If it fails to find an appropriate write descriptor, go > > > ahead and try for a read delegation if NFS4_SHARE_ACCESS_READ was > > > requested. > > > > > > This fixes xfstest generic/001. > > > > > > Closes: https://bugzilla.linux-nfs.org/show_bug.cgi?id=412 > > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > > --- > > > Changes in v2: > > > - Rework the logic when finding struct file for the delegation. The > > > earlier patch might still have attached a O_WRONLY file to the deleg > > > in some cases, and could still have handed out a write delegation on > > > an O_WRONLY OPEN request in some cases. > > > --- > > > fs/nfsd/nfs4state.c | 29 ++++++++++++++++++----------- > > > 1 file changed, 18 insertions(+), 11 deletions(-) > > > > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > > index ef7118ebee00..e79d82fd05e7 100644 > > > --- a/fs/nfsd/nfs4state.c > > > +++ b/fs/nfsd/nfs4state.c > > > @@ -5449,7 +5449,7 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, > > > struct nfs4_file *fp = stp->st_stid.sc_file; > > > struct nfs4_clnt_odstate *odstate = stp->st_clnt_odstate; > > > struct nfs4_delegation *dp; > > > - struct nfsd_file *nf; > > > + struct nfsd_file *nf = NULL; > > > struct file_lock *fl; > > > u32 dl_type; > > > > > > @@ -5461,21 +5461,28 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, > > > if (fp->fi_had_conflict) > > > return ERR_PTR(-EAGAIN); > > > > > > - if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) { > > > - nf = find_writeable_file(fp); > > > + /* > > > + * Try for a write delegation first. We need an O_RDWR file > > > + * since a write delegation allows the client to perform any open > > > + * from its cache. > > > + */ > > > + if ((open->op_share_access & NFS4_SHARE_ACCESS_BOTH) == NFS4_SHARE_ACCESS_BOTH) { > > > + nf = nfsd_file_get(fp->fi_fds[O_RDWR]); > > > > This doesn't take fp->fi_lock before accessing ->fi_fds[], while the > > find_readable_file() call below does. > > Note that the code it replaces (find_writeable_file) takes the fi_lock, > so that seems like an important omission. > Yes, you and Neil are correct. We need the lock there. I'll respin the patch, re-test and resend soon (once I sort out an issue with my test setup). > I noticed this earlier, but I was anxious to test whether this fix is > on the right path. So far, NFSv4.2 behavior seems much improved. And, > I like the new comments. > > > > This inconsistency suggests a bug? > > > > Maybe the provided API is awkward. Should we have > > find_suitable_file() and find_suitable_file_locked() > > that gets passed an nfs4_file and an O_MODE? > > It tries the given mode, then O_RDWR > > > > NeilBrown > > > > > > > dl_type = NFS4_OPEN_DELEGATE_WRITE; > > > - } else { > > > + } > > > + > > > + /* > > > + * If the file is being opened O_RDONLY or we couldn't get a O_RDWR > > > + * file for some reason, then try for a read deleg instead. > > > + */ > > > + if (!nf && (open->op_share_access & NFS4_SHARE_ACCESS_READ)) { > > > nf = find_readable_file(fp); > > > dl_type = NFS4_OPEN_DELEGATE_READ; > > > } > > > - if (!nf) { > > > - /* > > > - * We probably could attempt another open and get a read > > > - * delegation, but for now, don't bother until the > > > - * client actually sends us one. > > > - */ > > > + > > > + if (!nf) > > > return ERR_PTR(-EAGAIN); > > > - } > > > + > > > spin_lock(&state_lock); > > > spin_lock(&fp->fi_lock); > > > if (nfs4_delegation_exists(clp, fp)) > > > > > > --- > > > base-commit: a734662572708cf062e974f659ae50c24fc1ad17 > > > change-id: 20230731-wdeleg-bbdb6b25a3c6 > > > > > > Best regards, > > > -- > > > Jeff Layton <jlayton@xxxxxxxxxx> > > > > > > > > > -- Jeff Layton <jlayton@xxxxxxxxxx>
