From 2197e9b06c228b65a2cef98ef34d6bf42fa1af3d Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trondmy@gmail.com>
Date: Mon, 6 Jan 2020 15:25:03 -0500
Subject: [PATCH] NFS: Fix up fsync() when the server rebooted

Don't clear the NFS_CONTEXT_RESEND_WRITES flag until after calling
nfs_commit_inode(). Otherwise, if nfs_commit_inode() returns an
error, we end up with dirty pages in the page cache, but no tag
to tell us that those pages need resending.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
 fs/nfs/file.c | 37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index ccd9bc098806..f96367a2463e 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -204,44 +204,39 @@ EXPORT_SYMBOL_GPL(nfs_file_mmap);
 static int
 nfs_file_fsync_commit(struct file *file, int datasync)
 {
-	struct nfs_open_context *ctx = nfs_file_open_context(file);
 	struct inode *inode = file_inode(file);
-	int do_resend, status;
-	int ret = 0;
+	int ret;
 
 	dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync);
 
 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
-	do_resend = test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
-	status = nfs_commit_inode(inode, FLUSH_SYNC);
-	if (status == 0)
-		status = file_check_and_advance_wb_err(file);
-	if (status < 0) {
-		ret = status;
-		goto out;
-	}
-	do_resend |= test_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
-	if (do_resend)
-		ret = -EAGAIN;
-out:
-	return ret;
+	ret = nfs_commit_inode(inode, FLUSH_SYNC);
+	if (ret < 0)
+		return ret;
+	return file_check_and_advance_wb_err(file);
 }
 
 int
 nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
-	int ret;
+	struct nfs_open_context *ctx = nfs_file_open_context(file);
 	struct inode *inode = file_inode(file);
+	int ret;
 
 	trace_nfs_fsync_enter(inode);
 
-	do {
+	for (;;) {
 		ret = file_write_and_wait_range(file, start, end);
 		if (ret != 0)
 			break;
 		ret = nfs_file_fsync_commit(file, datasync);
-		if (!ret)
-			ret = pnfs_sync_inode(inode, !!datasync);
+		if (ret != 0)
+			break;
+		ret = pnfs_sync_inode(inode, !!datasync);
+		if (ret != 0)
+			break;
+		if (!test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags))
+			break;
 		/*
 		 * If nfs_file_fsync_commit detected a server reboot, then
 		 * resend all dirty pages that might have been covered by
@@ -249,7 +244,7 @@ nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 		 */
 		start = 0;
 		end = LLONG_MAX;
-	} while (ret == -EAGAIN);
+	}
 
 	trace_nfs_fsync_exit(inode, ret);
 	return ret;