libspl: staticify buf and pagesize, rename aok to libspl_assert_ok

Exporting names this short can easily cause nasty collisions with user code.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12050

cmd/zdb/zdb.c

@@ -8496,7 +8496,7 @@ main(int argc, char **argv)
 			dump_opt[c] += verbose;
 	}
 
-	aok = (dump_opt['A'] == 1) || (dump_opt['A'] > 2);
+	libspl_assert_ok = (dump_opt['A'] == 1) || (dump_opt['A'] > 2);
 	zfs_recover = (dump_opt['A'] > 1);
 
 	argc -= optind;

include/sys/zfs_context.h

@@ -160,8 +160,6 @@ extern void vpanic(const char *, va_list)  __NORETURN;
 
 #define	fm_panic	panic
 
-extern int aok;
-
 /*
  * DTrace SDT probes have different signatures in userland than they do in
  * the kernel.  If they're being used in kernel code, re-define them out of

lib/libspl/assert.c

@@ -25,7 +25,7 @@
 
 #include <assert.h>
 
-int aok = 0;
+int libspl_assert_ok = 0;
 
 /* printf version of libspl_assert */
 void
@@ -39,7 +39,7 @@ libspl_assertf(const char *file, const char *func, int line,
 	fprintf(stderr, "\n");
 	fprintf(stderr, "ASSERT at %s:%d:%s()", file, line, func);
 	va_end(args);
-	if (aok) {
+	if (libspl_assert_ok) {
 		return;
 	}
 	abort();

lib/libspl/include/assert.h

@@ -34,7 +34,7 @@
 #include <stdarg.h>
 
 /* Set to non-zero to avoid abort()ing on an assertion failure */
-extern int aok;
+extern int libspl_assert_ok;
 
 /* printf version of libspl_assert */
 extern void libspl_assertf(const char *file, const char *func, int line,

lib/libspl/os/linux/getmntany.c

@@ -41,7 +41,7 @@
 
 #define	BUFSIZE	(MNT_LINE_MAX + 2)
 
-__thread char buf[BUFSIZE];
+static __thread char buf[BUFSIZE];
 
 #define	DIFF(xx)	( \
 	    (mrefp->xx != NULL) && \

lib/libspl/page.c

@@ -22,7 +22,7 @@
 
 #include <unistd.h>
 
-size_t pagesize = 0;
+static size_t pagesize = 0;
 
 size_t
 spl_pagesize(void)