Add -c to zpool iostat & status to run command

This patch adds a command (-c) option to zpool status and zpool iostat.  The
-c option allows you to run an arbitrary command on each vdev and display
the first line of output in zpool status/iostat.  The environment vars
VDEV_PATH and VDEV_UPATH are set to the vdev's path and "underlying path"
before running the command.  For device mapper, multipath, or partitioned
vdevs, VDEV_UPATH is the actual underlying /dev/sd* disk.  This can be useful
if the command you're running requires a /dev/sd* device.

The patch also uses /sys/block/<dev>/slaves/ to lookup the underlying device
instead of using libdevmapper.  This not only removes the libdevmapper
requirement at build time, but also allows you to resolve device mapper
devices without being root.  This means that UDEV_UPATH get set correctly
when running zpool status/iostat as an unprivileged user.

Example:

$ zpool status -c 'echo I am $VDEV_PATH, $VDEV_UPATH'

NAME        STATE     READ WRITE CKSUM
mypool      ONLINE       0     0     0
  mirror-0  ONLINE       0     0     0
    mpatha  ONLINE       0     0     0  I am /dev/mapper/mpatha, /dev/sdc
    sdb     ONLINE       0     0     0  I am /dev/sdb1, /dev/sdb

Reviewed-by: Giuseppe Di Natale <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Tony Hutter <[email protected]>
Closes #5368 

1 files changed, 63 insertions, 6 deletions

diff --git a/cmd/zpool/zpool_main.c b/cmd/zpool/zpool_main.c
index b6702f22c..e50acbd2a 100644
--- a/cmd/zpool/zpool_main.c
+++ b/cmd/zpool/zpool_main.c
@@ -1510,8 +1510,23 @@ typedef struct status_cbdata {
 	boolean_t	cb_first;
 	boolean_t	cb_dedup_stats;
 	boolean_t	cb_print_status;
+	vdev_cmd_data_list_t	*vcdl;
 } status_cbdata_t;
 
+/* Print output line for specific vdev in a specific pool */
+static void
+zpool_print_cmd(vdev_cmd_data_list_t *vcdl, const char *pool, char *path)
+{
+	int i;
+	for (i = 0; i < vcdl->count; i++) {
+		if ((strcmp(vcdl->data[i].path, path) == 0) &&
+		    (strcmp(vcdl->data[i].pool, pool) == 0)) {
+			printf("%s", vcdl->data[i].line);
+			break;
+		}
+	}
+}
+
 /*
  * Print out configuration state as requested by status_callback.
  */
@@ -1528,6 +1543,7 @@ print_status_config(zpool_handle_t *zhp, status_cbdata_t *cb, const char *name,
 	uint64_t notpresent;
 	spare_cbdata_t spare_cb;
 	char *state;
+	char *path = NULL;
 
 	if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
 	    &child, &children) != 0)
@@ -1560,7 +1576,6 @@ print_status_config(zpool_handle_t *zhp, status_cbdata_t *cb, const char *name,
 
 	if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT,
 	    &notpresent) == 0) {
-		char *path;
 		verify(nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &path) == 0);
 		(void) printf("  was %s", path);
 	} else if (vs->vs_aux != 0) {
@@ -1641,6 +1656,13 @@ print_status_config(zpool_handle_t *zhp, status_cbdata_t *cb, const char *name,
 		    "resilvering" : "repairing");
 	}
 
+	if (cb->vcdl != NULL) {
+		if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &path) == 0) {
+			printf("  ");
+			zpool_print_cmd(cb->vcdl, zpool_get_name(zhp), path);
+		}
+	}
+
 	(void) printf("\n");
 
 	for (c = 0; c < children; c++) {
@@ -2586,6 +2608,7 @@ typedef struct iostat_cbdata {
 	boolean_t cb_literal;
 	boolean_t cb_scripted;
 	zpool_list_t *cb_list;
+	vdev_cmd_data_list_t *vcdl;
 } iostat_cbdata_t;
 
 /*  iostat labels */
@@ -3393,6 +3416,18 @@ print_vdev_stats(zpool_handle_t *zhp, const char *name, nvlist_t *oldnv,
 		print_iostat_histos(cb, oldnv, newnv, scale, name);
 	}
 
+	if (cb->vcdl != NULL) {
+		char *path;
+		if (nvlist_lookup_string(newnv, ZPOOL_CONFIG_PATH,
+		    &path) == 0) {
+			if (!(cb->cb_flags & IOS_ANYHISTO_M))
+				printf("  ");
+			zpool_print_cmd(cb->vcdl, zpool_get_name(zhp), path);
+			if (cb->cb_flags & IOS_ANYHISTO_M)
+				printf("\n");
+		}
+	}
+
 	if (!(cb->cb_flags & IOS_ANYHISTO_M))
 		printf("\n");
 
@@ -3924,10 +3959,11 @@ fsleep(float sec) {
 
 
 /*
- * zpool iostat [-ghHLpPvy] [[-lq]|[-r|-w]] [-n name] [-T d|u]
+ * zpool iostat [-c CMD] [-ghHLpPvy] [[-lq]|[-r|-w]] [-n name] [-T d|u]
  *		[[ pool ...]|[pool vdev ...]|[vdev ...]]
  *		[interval [count]]
  *
+ *	-c CMD  For each vdev, run command CMD
  *	-g	Display guid for individual vdev name.
  *	-L	Follow links when resolving vdev path name.
  *	-P	Display full path for vdev name.
@@ -3965,6 +4001,7 @@ zpool_do_iostat(int argc, char **argv)
 	boolean_t follow_links = B_FALSE;
 	boolean_t full_name = B_FALSE;
 	iostat_cbdata_t cb = { 0 };
+	char *cmd = NULL;
 
 	/* Used for printing error message */
 	const char flag_to_arg[] = {[IOS_LATENCY] = 'l', [IOS_QUEUES] = 'q',
@@ -3973,8 +4010,11 @@ zpool_do_iostat(int argc, char **argv)
 	uint64_t unsupported_flags;
 
 	/* check options */
-	while ((c = getopt(argc, argv, "gLPT:vyhplqrwH")) != -1) {
+	while ((c = getopt(argc, argv, "c:gLPT:vyhplqrwH")) != -1) {
 		switch (c) {
+		case 'c':
+			cmd = optarg;
+			break;
 		case 'g':
 			guid = B_TRUE;
 			break;
@@ -4167,7 +4207,6 @@ zpool_do_iostat(int argc, char **argv)
 		return (1);
 	}
 
-
 	for (;;) {
 		if ((npools = pool_list_count(list)) == 0)
 			(void) fprintf(stderr, gettext("no pools available\n"));
@@ -4217,8 +4256,15 @@ zpool_do_iostat(int argc, char **argv)
 				continue;
 			}
 
+			if (cmd != NULL)
+				cb.vcdl = all_pools_for_each_vdev_run(argc,
+				    argv, cmd);
+
 			pool_list_iter(list, B_FALSE, print_iostat, &cb);
 
+			if (cb.vcdl != NULL)
+				free_vdev_cmd_data_list(cb.vcdl);
+
 			/*
 			 * If there's more than one pool, and we're not in
 			 * verbose mode (which prints a separator for us),
@@ -6016,8 +6062,9 @@ status_callback(zpool_handle_t *zhp, void *data)
 }
 
 /*
- * zpool status [-gLPvx] [-T d|u] [pool] ... [interval [count]]
+ * zpool status [-c CMD] [-gLPvx] [-T d|u] [pool] ... [interval [count]]
  *
+ *	-c CMD	For each vdev, run command CMD
  *	-g	Display guid for individual vdev name.
  *	-L	Follow links when resolving vdev path name.
  *	-P	Display full path for vdev name.
@@ -6036,10 +6083,14 @@ zpool_do_status(int argc, char **argv)
 	float interval = 0;
 	unsigned long count = 0;
 	status_cbdata_t cb = { 0 };
+	char *cmd = NULL;
 
 	/* check options */
-	while ((c = getopt(argc, argv, "gLPvxDT:")) != -1) {
+	while ((c = getopt(argc, argv, "c:gLPvxDT:")) != -1) {
 		switch (c) {
+		case 'c':
+			cmd = optarg;
+			break;
 		case 'g':
 			cb.cb_name_flags |= VDEV_NAME_GUID;
 			break;
@@ -6083,9 +6134,15 @@ zpool_do_status(int argc, char **argv)
 		if (timestamp_fmt != NODATE)
 			print_timestamp(timestamp_fmt);
 
+		if (cmd != NULL)
+			cb.vcdl = all_pools_for_each_vdev_run(argc, argv, cmd);
+
 		ret = for_each_pool(argc, argv, B_TRUE, NULL,
 		    status_callback, &cb);
 
+		if (cb.vcdl != NULL)
+			free_vdev_cmd_data_list(cb.vcdl);
+
 		if (argc == 0 && cb.cb_count == 0)
 			(void) fprintf(stderr, gettext("no pools available\n"));
 		else if (cb.cb_explain && cb.cb_first && cb.cb_allpools)