cifs: clarify comment about timestamp granularity for old servers

It could be confusing why we set granularity to 1 seconds rather than 2 seconds (1 second is the max the VFS allows) for these mounts to very old servers ... Signed-off-by: Steve French <[email protected]>
dabrace · Oct 21, 2019 · 553292a · 553292a
1 parent d532cc7
commit 553292a
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
@@ -169,7 +169,13 @@ cifs_read_super(struct super_block *sb)
 	else
 		sb->s_maxbytes = MAX_NON_LFS;
 
-	/* Some very old servers like DOS and OS/2 used 2 second granularity */
+	/*
+	 * Some very old servers like DOS and OS/2 used 2 second granularity
+	 * (while all current servers use 100ns granularity - see MS-DTYP)
+	 * but 1 second is the maximum allowed granularity for the VFS
+	 * so for old servers set time granularity to 1 second while for
+	 * everything else (current servers) set it to 100ns.
+	 */
 	if ((tcon->ses->server->vals->protocol_id == SMB10_PROT_ID) &&
 	    ((tcon->ses->capabilities &
 	      tcon->ses->server->vals->cap_nt_find) == 0) &&