linux-kernel - Re: [PATCH v4 01/11] nfsd: fix initial getattr on write delegation

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Message-ID: <4eb752d9d8fabc0951df41762d92f751507292a3.camel@kernel.org>
Date: Sun, 08 Sep 2024 16:40:47 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>
Cc: Neil Brown <neilb@...e.de>, Olga Kornievskaia <okorniev@...hat.com>, Dai
 Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>, Trond Myklebust
 <trondmy@...nel.org>,  Anna Schumaker <anna@...nel.org>, Alexander Viro
 <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara
 <jack@...e.cz>, Tom Haynes <loghyr@...il.com>,  linux-nfs@...r.kernel.org,
 linux-kernel@...r.kernel.org,  linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v4 01/11] nfsd: fix initial getattr on write delegation

On Sun, 2024-09-08 at 14:00 -0400, Chuck Lever wrote:
> On Thu, Sep 05, 2024 at 08:41:45AM -0400, Jeff Layton wrote:
> > At this point in compound processing, currentfh refers to the parent of
> > the file, not the file itself. Get the correct dentry from the delegation
> > stateid instead.
> > 
> > Signed-off-by: Jeff Layton <jlayton@...nel.org>
> > ---
> >  fs/nfsd/nfs4state.c | 31 +++++++++++++++++++++++--------
> >  1 file changed, 23 insertions(+), 8 deletions(-)
> > 
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index df69dc6af467..db90677fc016 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -5914,6 +5914,26 @@ static void nfsd4_open_deleg_none_ext(struct nfsd4_open *open, int status)
> >  	}
> >  }
> >  
> > +static bool
> > +nfs4_delegation_stat(struct nfs4_delegation *dp, struct svc_fh *currentfh,
> > +		     struct kstat *stat)
> > +{
> > +	struct nfsd_file *nf = find_rw_file(dp->dl_stid.sc_file);
> 
> The xfstests workflow on NFSv4.2 exhausts the capacity of both the
> main and scratch devices (backed by xfs) about half-way through
> each test run.
> 
> Deleting all visible files on both devices frees only a little bit
> of space. The test exports can be unshared but not unmounted
> (EBUSY). Looks like unlinked but still open files, maybe.
> 
> Bisected to this here patch.
> 
> Should there be a matching nfsd_file_put() book-end for the new
> find_rw_file() call site?
> 

Yes. Braino on my end. I was thinking that find_rw_file didn't take a
reference, but it does and we do need to put it. Would you like me to
respin, or do you just want to add it in the appropriate spot?

> 
> > +	struct path path;
> > +
> > +	if (!nf)
> > +		return false;
> > +
> > +	path.mnt = currentfh->fh_export->ex_path.mnt;
> > +	path.dentry = file_dentry(nf->nf_file);
> > +
> > +	if (vfs_getattr(&path, stat,
> > +			(STATX_INO | STATX_SIZE | STATX_CTIME | STATX_CHANGE_COOKIE),
> > +			AT_STATX_SYNC_AS_STAT))
> > +		return false;
> > +	return true;
> > +}
> > +
> >  /*
> >   * The Linux NFS server does not offer write delegations to NFSv4.0
> >   * clients in order to avoid conflicts between write delegations and
> > @@ -5949,7 +5969,6 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
> >  	int cb_up;
> >  	int status = 0;
> >  	struct kstat stat;
> > -	struct path path;
> >  
> >  	cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
> >  	open->op_recall = false;
> > @@ -5985,20 +6004,16 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
> >  	memcpy(&open->op_delegate_stateid, &dp->dl_stid.sc_stateid, sizeof(dp->dl_stid.sc_stateid));
> >  
> >  	if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) {
> > -		open->op_delegate_type = NFS4_OPEN_DELEGATE_WRITE;
> > -		trace_nfsd_deleg_write(&dp->dl_stid.sc_stateid);
> > -		path.mnt = currentfh->fh_export->ex_path.mnt;
> > -		path.dentry = currentfh->fh_dentry;
> > -		if (vfs_getattr(&path, &stat,
> > -				(STATX_SIZE | STATX_CTIME | STATX_CHANGE_COOKIE),
> > -				AT_STATX_SYNC_AS_STAT)) {
> > +		if (!nfs4_delegation_stat(dp, currentfh, &stat)) {
> >  			nfs4_put_stid(&dp->dl_stid);
> >  			destroy_delegation(dp);
> >  			goto out_no_deleg;
> >  		}
> > +		open->op_delegate_type = NFS4_OPEN_DELEGATE_WRITE;
> >  		dp->dl_cb_fattr.ncf_cur_fsize = stat.size;
> >  		dp->dl_cb_fattr.ncf_initial_cinfo =
> >  			nfsd4_change_attribute(&stat, d_inode(currentfh->fh_dentry));
> > +		trace_nfsd_deleg_write(&dp->dl_stid.sc_stateid);
> >  	} else {
> >  		open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
> >  		trace_nfsd_deleg_read(&dp->dl_stid.sc_stateid);
> > 
> > -- 
> > 2.46.0
> > 
> 

-- 
Jeff Layton <jlayton@...nel.org>