From b1b85c8772ed28d2c8227e6d32905740817ae2c3 Mon Sep 17 00:00:00 2001
From: Tim Chase <tim@chase2k.com>
Date: Thu, 14 May 2015 12:45:56 -0500
Subject: [PATCH] Zdb should be able to open the root dataset

If the pool/dataset command-line argument is specified with a trailing
slash, for example, "tank/", it is interpreted as the root dataset.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3415
---
 cmd/zdb/zdb.c  | 12 +++++++++++-
 man/man8/zdb.8 |  5 +++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index 0740b5ca6e..d0bebbe60f 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -3572,6 +3572,7 @@ main(int argc, char **argv)
 	int rewind = ZPOOL_NEVER_REWIND;
 	char *spa_config_path_env;
 	const char *opts = "bcdhilmMI:suCDRSAFLXevp:t:U:P";
+	boolean_t target_is_spa = B_TRUE;
 
 	(void) setrlimit(RLIMIT_NOFILE, &rl);
 	(void) enable_extended_FILE_stdio(-1, -1);
@@ -3740,8 +3741,17 @@ main(int argc, char **argv)
 		}
 	}
 
+	if (strpbrk(target, "/@") != NULL) {
+		size_t targetlen;
+
+		target_is_spa = B_FALSE;
+		targetlen = strlen(target);
+		if (targetlen && target[targetlen - 1] == '/')
+			target[targetlen - 1] = '\0';
+	}
+
 	if (error == 0) {
-		if (strpbrk(target, "/@") == NULL || dump_opt['R']) {
+		if (target_is_spa || dump_opt['R']) {
 			error = spa_open_rewind(target, &spa, FTAG, policy,
 			    NULL);
 			if (error) {
diff --git a/man/man8/zdb.8 b/man/man8/zdb.8
index 2bfe9683b1..d19e4a39ff 100644
--- a/man/man8/zdb.8
+++ b/man/man8/zdb.8
@@ -55,6 +55,11 @@ The output of this command in general reflects the on-disk structure of a ZFS
 pool, and is inherently unstable. The precise output of most invocations is
 not documented, a knowledge of ZFS internals is assumed.
 
+.P
+If the \fIdataset\fR argument does not contain any \fB/\fR or \fB@\fR
+characters, it is interpreted as a pool name.  The root dataset can be
+specified as \fIpool\fB/\fR (pool name followed by a slash).
+
 .P
 When operating on an imported and active pool it is possible, though unlikely,
 that zdb may interpret inconsistent pool data and behave erratically.