NFSv4/pnfs: Allow layoutget to return EAGAIN for softerr mounts

If we're using the 'softerr' mount option, we may want to allow
layoutget to return EAGAIN to allow knfsd server threads to return a
JUKEBOX/DELAY error to the client instead of busy waiting.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

4 files changed, 22 insertions, 11 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 6f64fe97e72f..734643b60c48 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -9646,6 +9646,9 @@ nfs4_layoutget_handle_exception(struct rpc_task *task,
 
 	nfs4_sequence_free_slot(&lgp->res.seq_res);
 
+	exception->state = NULL;
+	exception->stateid = NULL;
+
 	switch (nfs4err) {
 	case 0:
 		goto out;
@@ -9741,7 +9744,8 @@ static const struct rpc_call_ops nfs4_layoutget_call_ops = {
 };
 
 struct pnfs_layout_segment *
-nfs4_proc_layoutget(struct nfs4_layoutget *lgp, long *timeout)
+nfs4_proc_layoutget(struct nfs4_layoutget *lgp,
+		    struct nfs4_exception *exception)
 {
 	struct inode *inode = lgp->args.inode;
 	struct nfs_server *server = NFS_SERVER(inode);
@@ -9761,13 +9765,10 @@ nfs4_proc_layoutget(struct nfs4_layoutget *lgp, long *timeout)
 			 RPC_TASK_MOVEABLE,
 	};
 	struct pnfs_layout_segment *lseg = NULL;
-	struct nfs4_exception exception = {
-		.inode = inode,
-		.timeout = *timeout,
-	};
 	int status = 0;
 
 	nfs4_init_sequence(&lgp->args.seq_args, &lgp->res.seq_res, 0, 0);
+	exception->retry = 0;
 
 	task = rpc_run_task(&task_setup_data);
 	if (IS_ERR(task))
@@ -9778,11 +9779,12 @@ nfs4_proc_layoutget(struct nfs4_layoutget *lgp, long *timeout)
 		goto out;
 
 	if (task->tk_status < 0) {
-		status = nfs4_layoutget_handle_exception(task, lgp, &exception);
-		*timeout = exception.timeout;
+		exception->retry = 1;
+		status = nfs4_layoutget_handle_exception(task, lgp, exception);
 	} else if (lgp->res.layoutp->len == 0) {
+		exception->retry = 1;
 		status = -EAGAIN;
-		*timeout = nfs4_update_delay(&exception.timeout);
+		nfs4_update_delay(&exception->timeout);
 	} else
 		lseg = pnfs_layout_process(lgp);
 out:
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 84343aefbbd6..21a365357629 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1980,7 +1980,9 @@ pnfs_update_layout(struct inode *ino,
 	struct pnfs_layout_segment *lseg = NULL;
 	struct nfs4_layoutget *lgp;
 	nfs4_stateid stateid;
-	long timeout = 0;
+	struct nfs4_exception exception = {
+		.inode = ino,
+	};
 	unsigned long giveup = jiffies + (clp->cl_lease_time << 1);
 	bool first;
 
@@ -2144,7 +2146,7 @@ lookup_again:
 	lgp->lo = lo;
 	pnfs_get_layout_hdr(lo);
 
-	lseg = nfs4_proc_layoutget(lgp, &timeout);
+	lseg = nfs4_proc_layoutget(lgp, &exception);
 	trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
 				 PNFS_UPDATE_LAYOUT_SEND_LAYOUTGET);
 	nfs_layoutget_end(lo);
@@ -2171,6 +2173,8 @@ lookup_again:
 			goto out_put_layout_hdr;
 		}
 		if (lseg) {
+			if (!exception.retry)
+				goto out_put_layout_hdr;
 			if (first)
 				pnfs_clear_first_layoutget(lo);
 			trace_pnfs_update_layout(ino, pos, count,
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index d886c8226d8f..db57a85500ee 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -35,6 +35,7 @@
 #include <linux/nfs_page.h>
 #include <linux/workqueue.h>
 
+struct nfs4_exception;
 struct nfs4_opendata;
 
 enum {
@@ -245,7 +246,9 @@ extern size_t max_response_pages(struct nfs_server *server);
 extern int nfs4_proc_getdeviceinfo(struct nfs_server *server,
 				   struct pnfs_device *dev,
 				   const struct cred *cred);
-extern struct pnfs_layout_segment* nfs4_proc_layoutget(struct nfs4_layoutget *lgp, long *timeout);
+extern struct pnfs_layout_segment *
+nfs4_proc_layoutget(struct nfs4_layoutget *lgp,
+		    struct nfs4_exception *exception);
 extern int nfs4_proc_layoutreturn(struct nfs4_layoutreturn *lrp, bool sync);
 
 /* pnfs.c */
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 9d82d50ce0b1..b664caea8b4e 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -739,6 +739,8 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 					&pgio);
 		pgio.pg_error = 0;
 		nfs_pageio_complete(&pgio);
+		if (err == -EAGAIN && mntflags & NFS_MOUNT_SOFTERR)
+			break;
 	} while (err < 0 && !nfs_error_is_fatal(err));
 	nfs_io_completion_put(ioc);