spa: Fix FreeBSD sysctl handlers

sbuf_cpy() resets the sbuf state, which is wrong for sbufs allocated by
sbuf_new_for_sysctl().  In particular, this code triggers an assertion
failure in sbuf_clear().

Simplify by just using sysctl_handle_string() for both reading and
setting the tunable.

Fixes: 6930ecbb7 ("spa: make read/write queues configurable")
Reviewed-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reported-by: Peter Holm <pho@FreeBSD.org>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Closes #15719

diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index a21b0decf6a3ccff565663965af155b49a65082c..dc8a99e7bd25688c2762c5a82aa9478fae007193 100644 (file)
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -1445,8 +1445,6 @@ spa_taskq_write_param_get(char *buf, zfs_kernel_param_t *kp)
        return (spa_taskq_param_get(ZIO_TYPE_WRITE, buf));
 }
 #else
-#include <sys/sbuf.h>
-
 /*
  * On FreeBSD load-time parameters can be set up before malloc() is available,
  * so we have to do all the parsing work on the stack.
@@ -1457,19 +1455,11 @@ static int
 spa_taskq_read_param(ZFS_MODULE_PARAM_ARGS)
 {
        char buf[SPA_TASKQ_PARAM_MAX];
-       int err = 0;
-
-       if (req->newptr == NULL) {
-               int len = spa_taskq_param_get(ZIO_TYPE_READ, buf);
-               struct sbuf *s = sbuf_new_for_sysctl(NULL, NULL, len+1, req);
-               sbuf_cpy(s, buf);
-               err = sbuf_finish(s);
-               sbuf_delete(s);
-               return (err);
-       }
+       int err;
 
+       (void) spa_taskq_param_get(ZIO_TYPE_READ, buf);
        err = sysctl_handle_string(oidp, buf, sizeof (buf), req);
-       if (err)
+       if (err || req->newptr == NULL)
                return (err);
        return (spa_taskq_param_set(ZIO_TYPE_READ, buf));
 }
@@ -1478,19 +1468,11 @@ static int
 spa_taskq_write_param(ZFS_MODULE_PARAM_ARGS)
 {
        char buf[SPA_TASKQ_PARAM_MAX];
-       int err = 0;
-
-       if (req->newptr == NULL) {
-               int len = spa_taskq_param_get(ZIO_TYPE_WRITE, buf);
-               struct sbuf *s = sbuf_new_for_sysctl(NULL, NULL, len+1, req);
-               sbuf_cpy(s, buf);
-               err = sbuf_finish(s);
-               sbuf_delete(s);
-               return (err);
-       }
+       int err;
 
+       (void) spa_taskq_param_get(ZIO_TYPE_WRITE, buf);
        err = sysctl_handle_string(oidp, buf, sizeof (buf), req);
-       if (err)
+       if (err || req->newptr == NULL)
                return (err);
        return (spa_taskq_param_set(ZIO_TYPE_WRITE, buf));
 }