nfs41: introduce NFS_LAYOUT_RETURN_BEFORE_CLOSE

When it is set, generic pnfs would try to send layoutreturn right
before last close/delegation_return regard less NFS_LAYOUT_ROC is
set or not. LD can then make sure layoutreturn is always sent
rather than being omitted.

The difference against NFS_LAYOUT_RETURN is that
NFS_LAYOUT_RETURN_BEFORE_CLOSE does not block usage of the layout so
LD can set it and expect generic layer to try pnfs path at the
same time.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <loghyr@primarydata.com>

fs/nfs/nfs4proc.c

@@ -7797,6 +7797,8 @@ static void nfs4_layoutreturn_release(void *calldata)
 	if (lrp->res.lrs_present)
 		pnfs_set_layout_stateid(lo, &lrp->res.stateid, true);
 	clear_bit(NFS_LAYOUT_RETURN, &lo->plh_flags);
+	clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags);
+	rpc_wake_up(&NFS_SERVER(lo->plh_inode)->roc_rpcwaitq);
 	lo->plh_block_lgets--;
 	spin_unlock(&lo->plh_inode->i_lock);
 	pnfs_put_layout_hdr(lrp->args.layout);

fs/nfs/pnfs.c

@@ -909,6 +909,7 @@ pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, nfs4_stateid stateid,
 		status = -ENOMEM;
 		spin_lock(&ino->i_lock);
 		lo->plh_block_lgets--;
+		rpc_wake_up(&NFS_SERVER(ino)->roc_rpcwaitq);
 		spin_unlock(&ino->i_lock);
 		pnfs_put_layout_hdr(lo);
 		goto out;
@@ -926,11 +927,6 @@ pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, nfs4_stateid stateid,
 
 	status = nfs4_proc_layoutreturn(lrp, sync);
 out:
-	if (status) {
-		spin_lock(&ino->i_lock);
-		clear_bit(NFS_LAYOUT_RETURN, &lo->plh_flags);
-		spin_unlock(&ino->i_lock);
-	}
 	dprintk("<-- %s status: %d\n", __func__, status);
 	return status;
 }
@@ -1028,8 +1024,9 @@ bool pnfs_roc(struct inode *ino)
 {
 	struct pnfs_layout_hdr *lo;
 	struct pnfs_layout_segment *lseg, *tmp;
+	nfs4_stateid stateid;
 	LIST_HEAD(tmp_list);
-	bool found = false;
+	bool found = false, layoutreturn = false;
 
 	spin_lock(&ino->i_lock);
 	lo = NFS_I(ino)->layout;
@@ -1050,7 +1047,20 @@ bool pnfs_roc(struct inode *ino)
 	return true;
 
 out_nolayout:
+	if (lo) {
+		stateid = lo->plh_stateid;
+		layoutreturn =
+			test_and_clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
+					   &lo->plh_flags);
+		if (layoutreturn) {
+			lo->plh_block_lgets++;
+			pnfs_get_layout_hdr(lo);
+		}
+	}
 	spin_unlock(&ino->i_lock);
+	if (layoutreturn)
+		pnfs_send_layoutreturn(lo, stateid, IOMODE_ANY, 0,
+				       NFS4_MAX_UINT64, true);
 	return false;
 }
 
@@ -1085,8 +1095,9 @@ bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
 	struct nfs_inode *nfsi = NFS_I(ino);
 	struct pnfs_layout_hdr *lo;
 	struct pnfs_layout_segment *lseg;
+	nfs4_stateid stateid;
 	u32 current_seqid;
-	bool found = false;
+	bool found = false, layoutreturn = false;
 
 	spin_lock(&ino->i_lock);
 	list_for_each_entry(lseg, &nfsi->layout->plh_segs, pls_list)
@@ -1103,7 +1114,22 @@ bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
 	 */
 	*barrier = current_seqid + atomic_read(&lo->plh_outstanding);
 out:
+	if (!found) {
+		stateid = lo->plh_stateid;
+		layoutreturn =
+			test_and_clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
+					   &lo->plh_flags);
+		if (layoutreturn) {
+			lo->plh_block_lgets++;
+			pnfs_get_layout_hdr(lo);
+		}
+	}
 	spin_unlock(&ino->i_lock);
+	if (layoutreturn) {
+		rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
+		pnfs_send_layoutreturn(lo, stateid, IOMODE_ANY, 0,
+				       NFS4_MAX_UINT64, false);
+	}
 	return found;
 }
 

fs/nfs/pnfs.h

@@ -96,6 +96,7 @@ enum {
 	NFS_LAYOUT_BULK_RECALL,		/* bulk recall affecting layout */
 	NFS_LAYOUT_ROC,			/* some lseg had roc bit set */
 	NFS_LAYOUT_RETURN,		/* Return this layout ASAP */
+	NFS_LAYOUT_RETURN_BEFORE_CLOSE,	/* Return this layout before close */
 	NFS_LAYOUT_INVALID_STID,	/* layout stateid id is invalid */
 	NFS_LAYOUT_FIRST_LAYOUTGET,	/* Serialize first layoutget */
 };