seq_file: Rename seq_overflow() to seq_has_overflowed() and make public

The return values of seq_printf/puts/putc are frequently misused.

Start down a path to remove all the return value uses of these
functions.

Move the seq_overflow() to a global inlined function called
seq_has_overflowed() that can be used by the users of seq_file() calls.

Update the documentation to not show return types for seq_printf
et al.  Add a description of seq_has_overflowed().

Link: http://lkml.kernel.org/p/848ac7e3d1c31cddf638a8526fa3c59fa6fdeb8a.1412031505.git.joe@perches.com

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Joe Perches <joe@perches.com>
[ Reworked the original patch from Joe ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 3857b72..353948b 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -16,17 +16,6 @@
 #include <asm/uaccess.h>
 #include <asm/page.h>
 
-
-/*
- * seq_files have a buffer which can may overflow. When this happens a larger
- * buffer is reallocated and all the data will be printed again.
- * The overflow state is true when m->count == m->size.
- */
-static bool seq_overflow(struct seq_file *m)
-{
-	return m->count == m->size;
-}
-
 static void seq_set_overflow(struct seq_file *m)
 {
 	m->count = m->size;
@@ -124,7 +113,7 @@
 			error = 0;
 			m->count = 0;
 		}
-		if (seq_overflow(m))
+		if (seq_has_overflowed(m))
 			goto Eoverflow;
 		if (pos + m->count > offset) {
 			m->from = offset - pos;
@@ -267,7 +256,7 @@
 			break;
 		}
 		err = m->op->show(m, p);
-		if (seq_overflow(m) || err) {
+		if (seq_has_overflowed(m) || err) {
 			m->count = offs;
 			if (likely(err <= 0))
 				break;