everywhere: misc unnecessary var init/update

These are all cases where we initialise or update a variable, and then
never use it. None of them particularly matter, as the compiler should
optimise them all away during dead store elimination, but some static
analysers complain about them and they are extra work for casual readers
to follow, so worth removing.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #17551

cmd/zdb/zdb.c

@@ -1991,7 +1991,7 @@ dump_ddt_log(ddt_t *ddt)
 				c += strlcpy(&flagstr[c], " UNKNOWN",
 				    sizeof (flagstr) - c);
 			flagstr[1] = '[';
-			flagstr[c++] = ']';
+			flagstr[c] = ']';
 		}
 
 		uint64_t count = avl_numnodes(&ddl->ddl_tree);
@@ -8800,7 +8800,6 @@ zdb_decompress_block(abd_t *pabd, void *buf, void *lbuf, uint64_t lsize,
 	(void) buf;
 	uint64_t orig_lsize = lsize;
 	boolean_t tryzle = ((getenv("ZDB_NO_ZLE") == NULL));
-	boolean_t found = B_FALSE;
 	/*
 	 * We don't know how the data was compressed, so just try
 	 * every decompress function at every inflated blocksize.
@@ -8843,20 +8842,19 @@ zdb_decompress_block(abd_t *pabd, void *buf, void *lbuf, uint64_t lsize,
 		for (cfuncp = cfuncs; *cfuncp; cfuncp++) {
 			if (try_decompress_block(pabd, lsize, psize, flags,
 			    *cfuncp, lbuf, lbuf2)) {
-				found = B_TRUE;
+				tryzle = B_FALSE;
 				break;
 			}
 		}
 		if (*cfuncp != 0)
 			break;
 	}
-	if (!found && tryzle) {
+	if (tryzle) {
 		for (lsize = orig_lsize; lsize <= maxlsize;
 		    lsize += SPA_MINBLOCKSIZE) {
 			if (try_decompress_block(pabd, lsize, psize, flags,
 			    ZIO_COMPRESS_ZLE, lbuf, lbuf2)) {
 				*cfuncp = ZIO_COMPRESS_ZLE;
-				found = B_TRUE;
 				break;
 			}
 		}

cmd/zed/zed_event.c

@@ -110,7 +110,7 @@ zed_event_fini(struct zed_conf *zcp)
 static void
 _bump_event_queue_length(void)
 {
-	int zzlm = -1, wr;
+	int zzlm, wr;
 	char qlen_buf[12] = {0}; /* parameter is int => max "-2147483647\n" */
 	long int qlen, orig_qlen;
 

cmd/zfs/zfs_main.c

@@ -1974,9 +1974,8 @@ fill_dataset_info(nvlist_t *list, zfs_handle_t *zhp, boolean_t as_int)
 	}
 
 	if (type == ZFS_TYPE_SNAPSHOT) {
-		char *ds, *snap;
-		ds = snap = strdup(zfs_get_name(zhp));
-		ds = strsep(&snap, "@");
+		char *snap = strdup(zfs_get_name(zhp));
+		char *ds = strsep(&snap, "@");
 		fnvlist_add_string(list, "dataset", ds);
 		fnvlist_add_string(list, "snapshot_name", snap);
 		free(ds);
@@ -2019,8 +2018,7 @@ get_callback(zfs_handle_t *zhp, void *data)
 	nvlist_t *user_props = zfs_get_user_props(zhp);
 	zprop_list_t *pl = cbp->cb_proplist;
 	nvlist_t *propval;
-	nvlist_t *item, *d, *props;
-	item = d = props = NULL;
+	nvlist_t *item, *d = NULL, *props = NULL;
 	const char *strval;
 	const char *sourceval;
 	boolean_t received = is_recvd_column(cbp);
@@ -5879,7 +5877,7 @@ parse_fs_perm_set(fs_perm_set_t *fspset, nvlist_t *nvl)
 static inline const char *
 deleg_perm_comment(zfs_deleg_note_t note)
 {
-	const char *str = "";
+	const char *str;
 
 	/* subcommands */
 	switch (note) {

cmd/zpool/zpool_iter.c

@@ -379,8 +379,8 @@ process_unique_cmd_columns(vdev_cmd_data_list_t *vcdl)
 static int
 vdev_process_cmd_output(vdev_cmd_data_t *data, char *line)
 {
-	char *col = NULL;
-	char *val = line;
+	char *col;
+	char *val;
 	char *equals;
 	char **tmp;
 
@@ -397,6 +397,7 @@ vdev_process_cmd_output(vdev_cmd_data_t *data, char *line)
 		col = line;
 		val = equals + 1;
 	} else {
+		col = NULL;
 		val = line;
 	}
 

cmd/zpool/zpool_main.c

@@ -1788,7 +1788,7 @@ zpool_do_labelclear(int argc, char **argv)
 {
 	char vdev[MAXPATHLEN];
 	char *name = NULL;
-	int c, fd = -1, ret = 0;
+	int c, fd, ret = 0;
 	nvlist_t *config;
 	pool_state_t state;
 	boolean_t inuse = B_FALSE;
@@ -6157,7 +6157,6 @@ static void
 get_interval_count_filter_guids(int *argc, char **argv, float *interval,
     unsigned long *count, iostat_cbdata_t *cb)
 {
-	char **tmpargv = argv;
 	int argc_for_interval = 0;
 
 	/* Is the last arg an interval value?  Or a guid? */
@@ -6181,7 +6180,7 @@ get_interval_count_filter_guids(int *argc, char **argv, float *interval,
 	}
 
 	/* Point to our list of possible intervals */
-	tmpargv = &argv[*argc - argc_for_interval];
+	char **tmpargv = &argv[*argc - argc_for_interval];
 
 	*argc = *argc - argc_for_interval;
 	get_interval_count(&argc_for_interval, tmpargv,
@@ -6377,7 +6376,6 @@ zpool_do_iostat(int argc, char **argv)
 	int npools;
 	float interval = 0;
 	unsigned long count = 0;
-	int winheight = 24;
 	zpool_list_t *list;
 	boolean_t verbose = B_FALSE;
 	boolean_t latency = B_FALSE, l_histo = B_FALSE, rq_histo = B_FALSE;
@@ -6673,7 +6671,7 @@ zpool_do_iostat(int argc, char **argv)
 			 * even when terminal window has its height
 			 * changed.
 			 */
-			winheight = terminal_height();
+			int winheight = terminal_height();
 			/*
 			 * Are we connected to TTY? If not, headers_once
 			 * should be true, to avoid breaking scripts.
@@ -10706,7 +10704,6 @@ status_callback_json(zpool_handle_t *zhp, void *data)
 	uint_t c;
 	vdev_stat_t *vs;
 	nvlist_t *item, *d, *load_info, *vds;
-	item = d = NULL;
 
 	/* If dedup stats were requested, also fetch dedupcached. */
 	if (cbp->cb_dedup_stats > 1)

cmd/zpool/zpool_vdev.c

@@ -574,7 +574,6 @@ get_replication(nvlist_t *nvroot, boolean_t fatal)
 				nvlist_t *cnv = child[c];
 				const char *path;
 				struct stat64 statbuf;
-				int64_t size = -1LL;
 				const char *childtype;
 				int fd, err;
 
@@ -656,7 +655,7 @@ get_replication(nvlist_t *nvroot, boolean_t fatal)
 				    statbuf.st_size == MAXOFFSET_T)
 					continue;
 
-				size = statbuf.st_size;
+				int64_t size = statbuf.st_size;
 
 				/*
 				 * Also make sure that devices and
@@ -1365,7 +1364,7 @@ is_grouping(const char *type, int *mindev, int *maxdev)
 static int
 draid_config_by_type(nvlist_t *nv, const char *type, uint64_t children)
 {
-	uint64_t nparity = 1;
+	uint64_t nparity;
 	uint64_t nspares = 0;
 	uint64_t ndata = UINT64_MAX;
 	uint64_t ngroups = 1;

cmd/ztest.c

@@ -919,7 +919,7 @@ ztest_parse_name_value(const char *input, ztest_shared_opts_t *zo)
 {
 	char name[32];
 	char *value;
-	int state = ZTEST_VDEV_CLASS_RND;
+	int state;
 
 	(void) strlcpy(name, input, sizeof (name));