NFS: Use of mapping_set_error() results in spurious errors

The use of mapping_set_error() in conjunction with calls to
filemap_check_errors() is problematic because every error gets reported
as either an EIO or an ENOSPC by filemap_check_errors() in functions
such as filemap_write_and_wait() or filemap_write_and_wait_range().
In almost all cases, we prefer to use the more nuanced wb errors.

Fixes: b8946d7bfb ("NFS: Revalidate the file mapping on all fatal writeback errors")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/write.c

@@ -316,7 +316,10 @@ static void nfs_mapping_set_error(struct page *page, int error)
 	struct address_space *mapping = page_file_mapping(page);
 
 	SetPageError(page);
-	mapping_set_error(mapping, error);
+	filemap_set_wb_err(mapping, error);
+	if (mapping->host)
+		errseq_set(&mapping->host->i_sb->s_wb_err,
+			   error == -ENOSPC ? -ENOSPC : -EIO);
 	nfs_set_pageerror(mapping);
 }