Re: [PATCH v2 2/3] nfsd: Offer write delegations for o_wronly opens

[kernel test robot <lkp@intel.com>]

Hi Sagi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.11-rc1 next-20240729]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sagi-Grimberg/nfsd-don-t-assume-copy-notify-when-preprocessing-the-stateid/20240729-044834
base:   linus/master
patch link:    https://lore.kernel.org/r/20240728204104.519041-3-sagi%40grimberg.me
patch subject: [PATCH v2 2/3] nfsd: Offer write delegations for o_wronly opens
config: sparc64-randconfig-r121-20240729 (https://download.01.org/0day-ci/archive/20240730/202407300630.V7R20Aao-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 14.1.0
reproduce: (https://download.01.org/0day-ci/archive/20240730/202407300630.V7R20Aao-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202407300630.V7R20Aao-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> fs/nfsd/nfs4state.c:5985:32: sparse: sparse: incorrect type in assignment (different base types) @@     expected int status @@     got restricted __be32 @@
   fs/nfsd/nfs4state.c:5985:32: sparse:     expected int status
   fs/nfsd/nfs4state.c:5985:32: sparse:     got restricted __be32
   fs/nfsd/nfs4state.c: note: in included file (through include/linux/wait.h, include/linux/wait_bit.h, include/linux/fs.h):
   include/linux/list.h:218:19: sparse: sparse: context imbalance in 'put_clnt_odstate' - unexpected unlock
   fs/nfsd/nfs4state.c:1197:9: sparse: sparse: context imbalance in 'nfs4_put_stid' - unexpected unlock

vim +5985 fs/nfsd/nfs4state.c

  5895	
  5896	/*
  5897	 * The Linux NFS server does not offer write delegations to NFSv4.0
  5898	 * clients in order to avoid conflicts between write delegations and
  5899	 * GETATTRs requesting CHANGE or SIZE attributes.
  5900	 *
  5901	 * With NFSv4.1 and later minorversions, the SEQUENCE operation that
  5902	 * begins each COMPOUND contains a client ID. Delegation recall can
  5903	 * be avoided when the server recognizes the client sending a
  5904	 * GETATTR also holds write delegation it conflicts with.
  5905	 *
  5906	 * However, the NFSv4.0 protocol does not enable a server to
  5907	 * determine that a GETATTR originated from the client holding the
  5908	 * conflicting delegation versus coming from some other client. Per
  5909	 * RFC 7530 Section 16.7.5, the server must recall or send a
  5910	 * CB_GETATTR even when the GETATTR originates from the client that
  5911	 * holds the conflicting delegation.
  5912	 *
  5913	 * An NFSv4.0 client can trigger a pathological situation if it
  5914	 * always sends a DELEGRETURN preceded by a conflicting GETATTR in
  5915	 * the same COMPOUND. COMPOUND execution will always stop at the
  5916	 * GETATTR and the DELEGRETURN will never get executed. The server
  5917	 * eventually revokes the delegation, which can result in loss of
  5918	 * open or lock state.
  5919	 */
  5920	static void
  5921	nfs4_open_delegation(struct svc_rqst *rqstp, struct nfsd4_open *open,
  5922			struct nfs4_ol_stateid *stp, struct svc_fh *currentfh)
  5923	{
  5924		struct nfs4_delegation *dp;
  5925		struct nfs4_openowner *oo = openowner(stp->st_stateowner);
  5926		struct nfs4_client *clp = stp->st_stid.sc_client;
  5927		struct svc_fh *parent = NULL;
  5928		int cb_up;
  5929		int status = 0;
  5930		struct kstat stat;
  5931		struct path path;
  5932	
  5933		cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
  5934		open->op_recall = false;
  5935		switch (open->op_claim_type) {
  5936			case NFS4_OPEN_CLAIM_PREVIOUS:
  5937				if (!cb_up)
  5938					open->op_recall = true;
  5939				break;
  5940			case NFS4_OPEN_CLAIM_NULL:
  5941				parent = currentfh;
  5942				fallthrough;
  5943			case NFS4_OPEN_CLAIM_FH:
  5944				/*
  5945				 * Let's not give out any delegations till everyone's
  5946				 * had the chance to reclaim theirs, *and* until
  5947				 * NLM locks have all been reclaimed:
  5948				 */
  5949				if (locks_in_grace(clp->net))
  5950					goto out_no_deleg;
  5951				if (!cb_up || !(oo->oo_flags & NFS4_OO_CONFIRMED))
  5952					goto out_no_deleg;
  5953				if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE &&
  5954						!clp->cl_minorversion)
  5955					goto out_no_deleg;
  5956				break;
  5957			default:
  5958				goto out_no_deleg;
  5959		}
  5960		dp = nfs4_set_delegation(open, stp, parent);
  5961		if (IS_ERR(dp))
  5962			goto out_no_deleg;
  5963	
  5964		memcpy(&open->op_delegate_stateid, &dp->dl_stid.sc_stateid, sizeof(dp->dl_stid.sc_stateid));
  5965	
  5966		if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) {
  5967			open->op_delegate_type = NFS4_OPEN_DELEGATE_WRITE;
  5968			trace_nfsd_deleg_write(&dp->dl_stid.sc_stateid);
  5969			path.mnt = currentfh->fh_export->ex_path.mnt;
  5970			path.dentry = currentfh->fh_dentry;
  5971			if (vfs_getattr(&path, &stat,
  5972					(STATX_SIZE | STATX_CTIME | STATX_CHANGE_COOKIE),
  5973					AT_STATX_SYNC_AS_STAT)) {
  5974				nfs4_put_stid(&dp->dl_stid);
  5975				destroy_delegation(dp);
  5976				goto out_no_deleg;
  5977			}
  5978			dp->dl_cb_fattr.ncf_cur_fsize = stat.size;
  5979			dp->dl_cb_fattr.ncf_initial_cinfo =
  5980				nfsd4_change_attribute(&stat, d_inode(currentfh->fh_dentry));
  5981			if ((open->op_share_access & NFS4_SHARE_ACCESS_BOTH) != NFS4_SHARE_ACCESS_BOTH) {
  5982				struct nfsd_file *nf = NULL;
  5983	
  5984				/* make sure the file is opened locally for O_RDWR */
> 5985				status = nfsd_file_acquire_opened(rqstp, currentfh,
  5986					nfs4_access_to_access(NFS4_SHARE_ACCESS_BOTH),
  5987					open->op_filp, &nf);
  5988				if (status) {
  5989					nfs4_put_stid(&dp->dl_stid);
  5990					destroy_delegation(dp);
  5991					goto out_no_deleg;
  5992				}
  5993				stp->st_stid.sc_file->fi_fds[O_RDWR] = nf;
  5994			}
  5995		} else {
  5996			open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
  5997			trace_nfsd_deleg_read(&dp->dl_stid.sc_stateid);
  5998		}
  5999		nfs4_put_stid(&dp->dl_stid);
  6000		return;
  6001	out_no_deleg:
  6002		open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE;
  6003		if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS &&
  6004		    open->op_delegate_type != NFS4_OPEN_DELEGATE_NONE) {
  6005			dprintk("NFSD: WARNING: refusing delegation reclaim\n");
  6006			open->op_recall = true;
  6007		}
  6008	
  6009		/* 4.1 client asking for a delegation? */
  6010		if (open->op_deleg_want)
  6011			nfsd4_open_deleg_none_ext(open, status);
  6012		return;
  6013	}
  6014	

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