FS: Replace http link to nfs sourceforge page by https.

checklink complains as follows:

	Code: 301 -> 200 OK
	To do: This is a permanent redirect. The link should be updated.

diff --git a/Filesystems.m4 b/Filesystems.m4
index 903b0b35a4ebcda8ab3a18997c7cc77617368744..24bff397fe5106b667bc89307236405c01387562 100644 (file)
--- a/Filesystems.m4
+++ b/Filesystems.m4
@@ -1432,7 +1432,7 @@ EXERCISES()
        <li> In an nfs-mounted directory (nfs version 4.0 or earlier), run
        <code>cat > foo &</code>. Note that the cat process automatically
        receives the STOP signal. Run <code>rm foo; ls -ltra</code>. Read
-       section D2 of the <a href="http://nfs.sourceforge.net/">nfs HOWTO</a>
+       section D2 of the <a href="https://nfs.sourceforge.net/">nfs HOWTO</a>
        for the explanation. </li>
 
        <li> In an nfs-mounted directory, run <code>{ while :; do echo; sleep
@@ -1441,7 +1441,7 @@ EXERCISES()
 
        <li> Discuss the pros and cons of hard vs. soft mounts. </li>
 
-       <li> Read section A10 of the <a href="http://nfs.sourceforge.net/">nfs
+       <li> Read section A10 of the <a href="https://nfs.sourceforge.net/">nfs
        HOWTO</a> to learn about common reasons for stale nfs handles. </li>
 
        <li> Can every local filesystem be exported via nfs? </li>
@@ -1508,9 +1508,12 @@ SECTION(«Further Reading»)
        <li> Dominic Giampaolo: Practical File System Design </li>
        <li> Cormen </li>
        <li> Darrick Wong: XFS Filesystem Disk Structures </li>
-       <li> The <a href="https://xfs.org/index.php/Main_Page">xfs FAQ</a> </li>
        <li> Documentation/filesystems/path-lookup.rst </li>
        <li> rfc 5531: Remote Procedure Call Protocol, Version 2 (2009) </li>
        <li> Birell, A.D. and Nelson, B.J.: Implementing Remote Procedure Calls
        (1984) </li>
+       <li> <a href="https://lwn.net/Articles/897917/">NFS: the early
+       years</a> and <a href="https://lwn.net/Articles/898262/">NFS: the new
+       millennium</a>, two articles on the design and history of NFS by Neil
+       Brown. </li>
 </ul>