[PATCH v4 3/4] 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/nfs4xdr.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 76db2fe29624..e069b970f136 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2920,6 +2920,46 @@ nfsd4_encode_bitmap(struct xdr_stream *xdr, u32 bmval0, u32 bmval1, u32 bmval2)
 	return nfserr_resource;
 }
 
+static struct file_lock *
+nfs4_wrdeleg_filelock(struct svc_rqst *rqstp, struct inode *inode)
+{
+	struct file_lock_context *ctx;
+	struct file_lock *fl;
+
+	ctx = locks_inode_context(inode);
+	if (!ctx)
+		return NULL;
+	spin_lock(&ctx->flc_lock);
+	if (!list_empty(&ctx->flc_lease)) {
+		fl = list_first_entry(&ctx->flc_lease,
+					struct file_lock, fl_list);
+		if (fl->fl_type == F_WRLCK) {
+			spin_unlock(&ctx->flc_lock);
+			return fl;
+		}
+	}
+	spin_unlock(&ctx->flc_lock);
+	return NULL;
+}
+
+static __be32
+nfs4_handle_wrdeleg_conflict(struct svc_rqst *rqstp, struct inode *inode)
+{
+	__be32 status;
+	struct file_lock *fl;
+	struct nfs4_delegation *dp;
+
+	fl = nfs4_wrdeleg_filelock(rqstp, inode);
+	if (!fl)
+		return 0;
+	dp = fl->fl_owner;
+	if (dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker))
+		return 0;
+	refcount_inc(&dp->dl_stid.sc_count);
+	status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
+	return status;
+}
+
 /*
  * Note: @fhp can be NULL; in this case, we might have to compose the filehandle
  * ourselves.
@@ -2966,6 +3006,11 @@ 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,
-- 
2.9.5