zpool: Add slot power control, print power status

Add `zpool` flags to control the slot power to drives.  This assumes
your SAS or NVMe enclosure supports slot power control via sysfs.

The new `--power` flag is added to `zpool offline|online|clear`:

    zpool offline --power <pool> <device>    Turn off device slot power
    zpool online --power <pool> <device>     Turn on device slot power
    zpool clear --power <pool> [device]      Turn on device slot power

If the ZPOOL_AUTO_POWER_ON_SLOT env var is set, then the '--power'
option is automatically implied for `zpool online` and `zpool clear`
and does not need to be passed.

zpool status also gets a --power option to print the slot power status.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Mart Frauenlob <AllKind@fastest.cc>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #15662

lib/libzutil/os/linux/zutil_import_os.c

@@ -188,25 +188,17 @@ zpool_open_func(void *arg)
 	if (rn->rn_labelpaths) {
 		char *path = NULL;
 		char *devid = NULL;
-		char *env = NULL;
 		rdsk_node_t *slice;
 		avl_index_t where;
-		int timeout;
 		int error;
 
 		if (label_paths(rn->rn_hdl, rn->rn_config, &path, &devid))
 			return;
 
-		env = getenv("ZPOOL_IMPORT_UDEV_TIMEOUT_MS");
-		if ((env == NULL) || sscanf(env, "%d", &timeout) != 1 ||
-		    timeout < 0) {
-			timeout = DISK_LABEL_WAIT;
-		}
-
 		/*
 		 * Allow devlinks to stabilize so all paths are available.
 		 */
-		zpool_label_disk_wait(rn->rn_name, timeout);
+		zpool_disk_wait(rn->rn_name);
 
 		if (path != NULL) {
 			slice = zutil_alloc(hdl, sizeof (rdsk_node_t));
@@ -700,6 +692,20 @@ zpool_label_disk_wait(const char *path, int timeout_ms)
 #endif /* HAVE_LIBUDEV */
 }
 
+/*
+ * Simplified version of zpool_label_disk_wait() where we wait for a device
+ * to appear using the default timeouts.
+ */
+int
+zpool_disk_wait(const char *path)
+{
+	int timeout;
+	timeout = zpool_getenv_int("ZPOOL_IMPORT_UDEV_TIMEOUT_MS",
+	    DISK_LABEL_WAIT);
+
+	return (zpool_label_disk_wait(path, timeout));
+}
+
 /*
  * Encode the persistent devices strings
  * used for the vdev disk label
@@ -782,6 +788,10 @@ no_dev:
  * in the nvlist * (if applicable).  Like:
  *    vdev_enc_sysfs_path: '/sys/class/enclosure/11:0:1:0/SLOT 4'
  *
+ * If an old path was in the nvlist, and the rescan can not find a new path,
+ * then keep the old path, since the disk may have been removed.
+ *
+ * path: The vdev path (value from ZPOOL_CONFIG_PATH)
  * key: The nvlist_t name (like ZPOOL_CONFIG_VDEV_ENC_SYSFS_PATH)
  */
 void
@@ -789,6 +799,9 @@ update_vdev_config_dev_sysfs_path(nvlist_t *nv, const char *path,
     const char *key)
 {
 	char *upath, *spath;
+	char *oldpath = NULL;
+
+	(void) nvlist_lookup_string(nv, key, &oldpath);
 
 	/* Add enclosure sysfs path (if disk is in an enclosure). */
 	upath = zfs_get_underlying_path(path);
@@ -797,7 +810,14 @@ update_vdev_config_dev_sysfs_path(nvlist_t *nv, const char *path,
 	if (spath) {
 		(void) nvlist_add_string(nv, key, spath);
 	} else {
-		(void) nvlist_remove_all(nv, key);
+		/*
+		 * We couldn't dynamically scan the disk's enclosure sysfs path.
+		 * This could be because the disk went away.  If there's an old
+		 * enclosure sysfs path in the nvlist, then keep using it.
+		 */
+		if (!oldpath) {
+			(void) nvlist_remove_all(nv, key);
+		}
 	}
 
 	free(upath);

lib/libzutil/zutil_import.c

@@ -1836,6 +1836,104 @@ zpool_find_config(void *hdl, const char *target, nvlist_t **configp,
 	return (0);
 }
 
+/* Return if a vdev is a leaf vdev.  Note: draid spares are leaf vdevs. */
+static boolean_t
+vdev_is_leaf(nvlist_t *nv)
+{
+	uint_t children = 0;
+	nvlist_t **child;
+
+	(void) nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
+	    &child, &children);
+
+	return (children == 0);
+}
+
+/* Return if a vdev is a leaf vdev and a real device (disk or file) */
+static boolean_t
+vdev_is_real_leaf(nvlist_t *nv)
+{
+	char *type = NULL;
+	if (!vdev_is_leaf(nv))
+		return (B_FALSE);
+
+	(void) nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE, &type);
+	if ((strcmp(type, VDEV_TYPE_DISK) == 0) ||
+	    (strcmp(type, VDEV_TYPE_FILE) == 0)) {
+		return (B_TRUE);
+	}
+
+	return (B_FALSE);
+}
+
+/*
+ * This function is called by our FOR_EACH_VDEV() macros.
+ *
+ * state:   State machine status (stored inside of a (nvlist_t *))
+ * nv:	     The current vdev nvlist_t we are iterating over.
+ * last_nv: The previous vdev nvlist_t we returned to the user in
+ *          the last iteration of FOR_EACH_VDEV().  We use it
+ *          to find the next vdev nvlist_t we should return.
+ * real_leaves_only: Only return leaf vdevs.
+ *
+ * Returns 1 if we found the next vdev nvlist_t for this iteration.  0 if
+ * we're still searching for it.
+ */
+static int
+__for_each_vdev_macro_helper_func(void *state, nvlist_t *nv, void *last_nv,
+    boolean_t real_leaves_only)
+{
+	enum {FIRST_NV = 0, NEXT_IS_MATCH = 1, STOP_LOOKING = 2};
+
+	/* The very first entry in the NV list is a special case */
+	if (*((nvlist_t **)state) == (nvlist_t *)FIRST_NV) {
+		if (real_leaves_only && !vdev_is_real_leaf(nv))
+			return (0);
+
+		*((nvlist_t **)last_nv) = nv;
+		*((nvlist_t **)state) = (nvlist_t *)STOP_LOOKING;
+		return (1);
+	}
+
+	/*
+	 * We came across our last_nv, meaning the next one is the one we
+	 * want
+	 */
+	if (nv == *((nvlist_t **)last_nv)) {
+		/* Next iteration of this function will return the nvlist_t */
+		*((nvlist_t **)state) = (nvlist_t *)NEXT_IS_MATCH;
+		return (0);
+	}
+
+	/*
+	 * We marked NEXT_IS_MATCH on the previous iteration, so this is the one
+	 * we want.
+	 */
+	if (*(nvlist_t **)state == (nvlist_t *)NEXT_IS_MATCH) {
+		if (real_leaves_only && !vdev_is_real_leaf(nv))
+			return (0);
+
+		*((nvlist_t **)last_nv) = nv;
+		*((nvlist_t **)state) = (nvlist_t *)STOP_LOOKING;
+		return (1);
+	}
+
+	return (0);
+}
+
+int
+for_each_vdev_macro_helper_func(void *state, nvlist_t *nv, void *last_nv)
+{
+	return (__for_each_vdev_macro_helper_func(state, nv, last_nv, B_FALSE));
+}
+
+int
+for_each_real_leaf_vdev_macro_helper_func(void *state, nvlist_t *nv,
+    void *last_nv)
+{
+	return (__for_each_vdev_macro_helper_func(state, nv, last_nv, B_TRUE));
+}
+
 /*
  * Internal function for iterating over the vdevs.
  *

lib/libzutil/zutil_pool.c

@@ -28,6 +28,7 @@
 #include <string.h>
 #include <sys/nvpair.h>
 #include <sys/fs/zfs.h>
+#include <math.h>
 
 #include <libzutil.h>
 
@@ -143,3 +144,33 @@ zpool_history_unpack(char *buf, uint64_t bytes_read, uint64_t *leftover,
 	*leftover = bytes_read;
 	return (0);
 }
+
+/*
+ * Floating point sleep().  Allows you to pass in a floating point value for
+ * seconds.
+ */
+void
+fsleep(float sec)
+{
+	struct timespec req;
+	req.tv_sec = floor(sec);
+	req.tv_nsec = (sec - (float)req.tv_sec) * NANOSEC;
+	nanosleep(&req, NULL);
+}
+
+/*
+ * Get environment variable 'env' and return it as an integer.
+ * If 'env' is not set, then return 'default_val' instead.
+ */
+int
+zpool_getenv_int(const char *env, int default_val)
+{
+	char *str;
+	int val;
+	str = getenv(env);
+	if ((str == NULL) || sscanf(str, "%d", &val) != 1 ||
+	    val < 0) {
+		val = default_val;
+	}
+	return (val);
+}