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LU-12400 zfs: zfs mainline 0.8+ with mainline (5.2) kernel
[fs/lustre-release.git] / lustre / utils / libmount_utils_zfs.c
index 770a053..a4fe85e 100644 (file)
 /*
  * Author: Brian Behlendorf <behlendorf1@llnl.gov>
  */
+#ifndef HAVE_ZFS_MULTIHOST
+#include <sys/list.h>
+#define list_move_tail(a, b) spl_list_move_tail(a, b)
+#include <sys/spa.h>
+#endif
 #include "mount_utils.h"
 #include <stddef.h>
 #include <stdio.h>
@@ -187,6 +192,114 @@ static int zfs_erase_allprops(zfs_handle_t *zhp)
 
        return 0;
 }
+/*
+ * ZFS on linux 0.7.0-rc5 commit 379ca9cf2beba802f096273e89e30914a2d6bafc
+ * Multi-modifier protection (MMP)
+ *
+ * Introduced spa_get_hostid() along with a few constants like
+ * ZPOOL_CONFIG_MMP_HOSTID that can be checked to imply availablity of
+ * spa_get_hostid. Supply a fallback when spa_get_hostid is not
+ * available.
+ *
+ * This can be removed when zfs 0.6.x support is dropped.
+ */
+#if !defined(ZPOOL_CONFIG_MMP_HOSTID) && !defined(HAVE_ZFS_MULTIHOST)
+unsigned long _hostid_from_proc(void)
+{
+       FILE *f;
+       unsigned long hostid;
+       int rc;
+
+       f = fopen("/proc/sys/kernel/spl/hostid", "r");
+       if (f == NULL)
+               goto out;
+
+       rc = fscanf(f, "%lx", &hostid);
+       fclose(f);
+       if (rc == 1)
+               return hostid;
+out:
+       return 0;
+}
+
+unsigned long _hostid_from_module_param(void)
+{
+       FILE *f;
+       unsigned long hostid;
+       int rc;
+
+       f = fopen("/sys/module/spl/parameters/spl_hostid", "r");
+       if (f == NULL)
+               goto out;
+
+       rc = fscanf(f, "%li", &hostid);
+       fclose(f);
+       if (rc == 1)
+               return hostid;
+out:
+       return 0;
+}
+
+unsigned long _from_module_param_indirect(void)
+{
+       FILE *f;
+       unsigned long hostid = 0;
+       uint32_t hwid;
+       int rc;
+       char *spl_hostid_path = NULL;
+
+       /* read the module parameter for HW_HOSTID_PATH */
+       f = fopen("/sys/module/spl/parameters/spl_hostid_path", "r");
+       if (f == NULL) {
+               fatal();
+               fprintf(stderr, "Failed to open spl_hostid_path param: %s\n",
+                       strerror(errno));
+               goto out;
+       }
+
+       rc = fscanf(f, "%ms%*[\n]", &spl_hostid_path);
+       fclose(f);
+       if (rc == 0 || !spl_hostid_path)
+               goto out;
+
+       /* read the hostid from the file */
+       f = fopen(spl_hostid_path, "r");
+       if (f == NULL) {
+               fatal();
+               fprintf(stderr, "Failed to open %s param: %s\n",
+                       spl_hostid_path, strerror(errno));
+               goto out;
+       }
+
+       /* hostid is the first 4 bytes in native endian order */
+       rc = fread(&hwid, sizeof(uint32_t), 1, f);
+       fclose(f);
+       if (rc == 1)
+               hostid = (unsigned long)hwid;
+
+out:
+       if (spl_hostid_path)
+               free(spl_hostid_path);
+
+       return hostid;
+}
+
+unsigned long spa_get_hostid(void)
+{
+       unsigned long hostid;
+
+       hostid = _hostid_from_proc();
+       if (hostid)
+               return hostid;
+
+       /* if /proc isn't available, try /sys */
+       hostid = _hostid_from_module_param();
+       if (hostid)
+               return hostid;
+
+       return _from_module_param_indirect();
+}
+#endif
 
 /*
  * Map '<key>=<value> ...' pairs in the passed string to dataset properties
@@ -237,10 +350,6 @@ static int zfs_set_prop_params(zfs_handle_t *zhp, char *params)
 static int zfs_check_hostid(struct mkfs_opts *mop)
 {
        unsigned long hostid;
-#ifndef HAVE_ZFS_MULTIHOST
-       FILE *f;
-       int rc;
-#endif
 
        if (strstr(mop->mo_ldd.ldd_params, PARAM_FAILNODE) == NULL)
                return 0;
@@ -248,44 +357,7 @@ static int zfs_check_hostid(struct mkfs_opts *mop)
 #ifdef HAVE_ZFS_MULTIHOST
        hostid = get_system_hostid();
 #else
-       /* This reimplements libzfs2::get_system_hostid() from 0.7+ because
-        * prior to 0.7.0 (MULTIHOST support), get_system_hostid() would return
-        * gethostid() if spl_hostid was 0, which would generate a hostid if
-        * /etc/hostid wasn't set, which is incompatible with the kernel
-        * implementation.
-        */
-       f = fopen("/sys/module/spl/parameters/spl_hostid", "r");
-       if (f == NULL) {
-               fatal();
-               fprintf(stderr, "Failed to open spl_hostid: %s\n",
-                       strerror(errno));
-               return errno;
-       }
-       rc = fscanf(f, "%li", &hostid);
-       fclose(f);
-       if (rc != 1) {
-               fatal();
-               fprintf(stderr, "Failed to read spl_hostid: %d\n", rc);
-               return rc;
-       }
-
-       if (hostid != 0)
-               return 0;
-
-       f = fopen(HW_HOSTID_PATH, "r");
-       if (f == NULL)
-               goto out;
-
-       rc = fread(&hostid, sizeof(uint32_t), 1, f);
-       fclose(f);
-
-       if (rc != 1) {
-               fprintf(stderr, "Failed to read "HW_HOSTID_PATH": %d\n",
-                      rc);
-               hostid = 0;
-       }
-
-out:
+       hostid = spa_get_hostid();
 #endif
        if (hostid == 0) {
                if (mop->mo_flags & MO_NOHOSTID_CHECK) {