[PATCH v5 2/3] NFSD: handle GETATTR conflict with write delegation

[Dai Ngo <dai.ngo@xxxxxxxxxx>]

If the GETATTR request on a file that has write delegation in effect
and the request attributes include the change info and size attribute
then the write delegation is recalled and NFS4ERR_DELAY is returned
for the GETATTR.

Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
---
 fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
 fs/nfsd/nfs4xdr.c   |  5 +++++
 fs/nfsd/state.h     |  3 +++
 3 files changed, 45 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b90b74a5e66e..ea9cd781db5f 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -8353,3 +8353,40 @@ nfsd4_get_writestateid(struct nfsd4_compound_state *cstate,
 {
 	get_stateid(cstate, &u->write.wr_stateid);
 }
+
+__be32
+nfs4_handle_wrdeleg_conflict(struct svc_rqst *rqstp, struct inode *inode)
+{
+	struct file_lock_context *ctx;
+	struct file_lock *fl;
+	struct nfs4_delegation *dp;
+
+	ctx = locks_inode_context(inode);
+	if (!ctx)
+		return 0;
+	spin_lock(&ctx->flc_lock);
+	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
+		if (fl->fl_flags == FL_LAYOUT ||
+				fl->fl_lmops != &nfsd_lease_mng_ops)
+			continue;
+		if (fl->fl_type == F_WRLCK) {
+			dp = fl->fl_owner;
+			/*
+			 * increment the sc_count to prevent the delegation to
+			 * be freed while sending the CB_RECALL. The refcount is
+			 * decremented by nfs4_put_stid in nfsd4_cb_recall_release
+			 * after the request was sent.
+			 */
+			if (dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker) ||
+					!refcount_inc_not_zero(&dp->dl_stid.sc_count)) {
+				spin_unlock(&ctx->flc_lock);
+				return 0;
+			}
+			spin_unlock(&ctx->flc_lock);
+			return nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
+		}
+		break;
+	}
+	spin_unlock(&ctx->flc_lock);
+	return 0;
+}
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 76db2fe29624..ed09b575afac 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2966,6 +2966,11 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
 		if (status)
 			goto out;
 	}
+	if (bmval0 & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
+		status = nfs4_handle_wrdeleg_conflict(rqstp, d_inode(dentry));
+		if (status)
+			goto out;
+	}
 
 	err = vfs_getattr(&path, &stat,
 			  STATX_BASIC_STATS | STATX_BTIME | STATX_CHANGE_COOKIE,
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index d49d3060ed4f..64727a39f0db 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -732,4 +732,7 @@ static inline bool try_to_expire_client(struct nfs4_client *clp)
 	cmpxchg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
 	return clp->cl_state == NFSD4_EXPIRABLE;
 }
+
+extern __be32 nfs4_handle_wrdeleg_conflict(struct svc_rqst *rqstp,
+				struct inode *inode);
 #endif   /* NFSD4_STATE_H */
-- 
2.9.5