Update utsname support

Modify the code to use the utsname() kernel function rather than
a global variable.  This results is cleaner more portable code
because utsname() is already provided by the kernel and can be
easily emulated in user space via uname(2).  This means that it
will behave consistently in both contexts.

This is also has the benefit that it allows the removal of a few
_KERNEL pre-processor conditions.  And it also is a pre-requisite
for a proper FUSE port because we need to provide a valid utsname.

Finally, it allows us to remove this functionality from the SPL
and all the related compatibility code.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2757

module/zfs/spa_config.c

@@ -32,7 +32,6 @@
 #include <sys/fs/zfs.h>
 #include <sys/vdev_impl.h>
 #include <sys/zfs_ioctl.h>
-#include <sys/utsname.h>
 #include <sys/systeminfo.h>
 #include <sys/sunddi.h>
 #include <sys/zfeature.h>
@@ -408,8 +407,8 @@ spa_config_generate(spa_t *spa, vdev_t *vd, uint64_t txg, int getstats)
 		VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_HOSTID,
 		    hostid) == 0);
 	}
-	VERIFY(nvlist_add_string(config, ZPOOL_CONFIG_HOSTNAME,
-	    utsname.nodename) == 0);
+	VERIFY0(nvlist_add_string(config, ZPOOL_CONFIG_HOSTNAME,
+	    utsname()->nodename));
 
 	if (vd != rvd) {
 		VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_TOP_GUID,

module/zfs/spa_history.c

@@ -32,7 +32,6 @@
 #include <sys/dmu_objset.h>
 #include <sys/dsl_dataset.h>
 #include <sys/dsl_dir.h>
-#include <sys/utsname.h>
 #include <sys/cmn_err.h>
 #include <sys/sunddi.h>
 #include <sys/cred.h>
@@ -236,9 +235,8 @@ spa_history_log_sync(void *arg, dmu_tx_t *tx)
 #endif
 
 	fnvlist_add_uint64(nvl, ZPOOL_HIST_TIME, gethrestime_sec());
-#ifdef _KERNEL
-	fnvlist_add_string(nvl, ZPOOL_HIST_HOST, utsname.nodename);
-#endif
+	fnvlist_add_string(nvl, ZPOOL_HIST_HOST, utsname()->nodename);
+
 	if (nvlist_exists(nvl, ZPOOL_HIST_CMD)) {
 		zfs_dbgmsg("command: %s",
 		    fnvlist_lookup_string(nvl, ZPOOL_HIST_CMD));
@@ -546,11 +544,12 @@ spa_history_log_internal_dd(dsl_dir_t *dd, const char *operation,
 void
 spa_history_log_version(spa_t *spa, const char *operation)
 {
+	utsname_t *u = utsname();
+
 	spa_history_log_internal(spa, operation, NULL,
 	    "pool version %llu; software version %llu/%d; uts %s %s %s %s",
 	    (u_longlong_t)spa_version(spa), SPA_VERSION, ZPL_VERSION,
-	    utsname.nodename, utsname.release, utsname.version,
-	    utsname.machine);
+	    u->nodename, u->release, u->version, u->machine);
 }
 
 #if defined(_KERNEL) && defined(HAVE_SPL)