nfsd: fix /proc/net/rpc/nfsd.export/content display

Note with "first" always 0, and "lastflags" initially 0, we always dump
a spurious set of 0 flags at the start, among other problems.

Fix.  And attempt to make the code a little more obvious.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 29 insertions, 11 deletions

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index a3c7d0ceb24f..067e2e612e2d 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -1470,25 +1470,43 @@ static void show_secinfo_flags(struct seq_file *m, int flags)
         show_expflags(m, flags, NFSEXP_SECINFO_FLAGS);
 }
 
+static bool secinfo_flags_equal(int f, int g)
+{
+        f &= NFSEXP_SECINFO_FLAGS;
+        g &= NFSEXP_SECINFO_FLAGS;
+        return f == g;
+}
+
+static int show_secinfo_run(struct seq_file *m, struct exp_flavor_info **fp, struct exp_flavor_info *end)
+{
+        int flags;
+
+        flags = (*fp)->flags;
+        seq_printf(m, ",sec=%d", (*fp)->pseudoflavor);
+        (*fp)++;
+        while (*fp != end && secinfo_flags_equal(flags, (*fp)->flags)) {
+                seq_printf(m, ":%d", (*fp)->pseudoflavor);
+                (*fp)++;
+        }
+        return flags;
+}
+
 static void show_secinfo(struct seq_file *m, struct svc_export *exp)
 {
         struct exp_flavor_info *f;
         struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
-        int lastflags = 0, first = 0;
+        int flags;
 
         if (exp->ex_nflavors == 0)
                 return;
-        for (f = exp->ex_flavors; f < end; f++) {
-                if (first || f->flags != lastflags) {
-                        if (!first)
-                                show_secinfo_flags(m, lastflags);
-                        seq_printf(m, ",sec=%d", f->pseudoflavor);
-                        lastflags = f->flags;
-                } else {
-                        seq_printf(m, ":%d", f->pseudoflavor);
-                }
+        f = exp->ex_flavors;
+        flags = show_secinfo_run(m, &f, end);
+        if (!secinfo_flags_equal(flags, exp->ex_flags))
+                show_secinfo_flags(m, flags);
+        while (f != end) {
+                flags = show_secinfo_run(m, &f, end);
+                show_secinfo_flags(m, flags);
         }
-        show_secinfo_flags(m, lastflags);
 }
 
 static void exp_flags(struct seq_file *m, int flag, int fsid,