git: f6745503ded7 - stable/15 - Make zvol_set_common() block until the operation has completed

The branch stable/15 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=f6745503ded7cc938a52d6916277da12c5b31d4f

commit f6745503ded7cc938a52d6916277da12c5b31d4f
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2026-02-02 01:55:04 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-07-27 17:29:03 +0000

    Make zvol_set_common() block until the operation has completed
    
    This is motivated by a FreeBSD AIO test case which create a zvol with -o
    volmode=dev, then immediately tries to open the zvol device file.  The
    open occasionally fails with ENOENT.
    
    When a zvol is created without the volmode setting, zvol_create_minors()
    blocks until the task is finished, at which point OS-dependent code will
    have created a device file.  However, zvol_set_common() may cause the
    device file to be destroyed and re-created, at least on FreeBSD, if the
    voltype switches from GEOM to DEV.  In this case, we do not block
    waiting for the operation to finish, causing the test failure.
    
    Fix the problem by making zvol_set_common() block until the operation
    has finished.  In FreeBSD zvol code, use g_waitidle() to block until
    asynchronous GEOM operations are done.  This fixes a secondary race
    where zvol_os_remove_minor() does not block until the zvol device file
    is removed, and the subsequent zvol_os_create_minor() fails because the
    (to-be-destroyed) device file already exists.
    
    Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
    Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
    Signed-off-by: Mark Johnston <markj@FreeBSD.org>
    Closes #18191
    (cherry picked from commit d736868672cb3df197d2ddcfef29ac14edf4ee20)
---
 .../openzfs/module/os/freebsd/zfs/zvol_os.c        |  4 +-
 sys/contrib/openzfs/module/zfs/zvol.c              | 46 ++++++++++++++++++++--
 2 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zvol_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zvol_os.c
index fca99c42f73c..2bc85e9bd972 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zvol_os.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zvol_os.c
@@ -919,7 +919,7 @@ retry:
 		return (SET_ERROR(ENXIO));
 
 	mutex_enter(&zv->zv_state_lock);
-	if (zv->zv_zso->zso_dying || zv->zv_flags & ZVOL_REMOVING) {
+	if (zv->zv_flags & ZVOL_REMOVING || zv->zv_zso->zso_dying) {
 		err = SET_ERROR(ENXIO);
 		goto out_locked;
 	}
@@ -1426,6 +1426,7 @@ zvol_os_remove_minor(zvol_state_t *zv)
 		pp->private = NULL;
 		g_wither_geom(pp->geom, ENXIO);
 		g_topology_unlock();
+		g_waitidle(curthread);
 	} else if (zv->zv_volmode == ZFS_VOLMODE_DEV) {
 		struct zvol_state_dev *zsd = &zso->zso_dev;
 		struct cdev *dev = zsd->zsd_cdev;
@@ -1555,6 +1556,7 @@ out_dmu_objset_disown:
 		g_error_provider(zv->zv_zso->zso_geom.zsg_provider, 0);
 		/* geom was locked inside zvol_alloc() function */
 		g_topology_unlock();
+		g_waitidle(curthread);
 	}
 out_doi:
 	kmem_free(doi, sizeof (dmu_object_info_t));
diff --git a/sys/contrib/openzfs/module/zfs/zvol.c b/sys/contrib/openzfs/module/zfs/zvol.c
index 15ee62ca5249..185672672a2f 100644
--- a/sys/contrib/openzfs/module/zfs/zvol.c
+++ b/sys/contrib/openzfs/module/zfs/zvol.c
@@ -1952,6 +1952,10 @@ typedef struct zvol_set_prop_int_arg {
 	uint64_t zsda_value;
 	zprop_source_t zsda_source;
 	zfs_prop_t zsda_prop;
+	taskqid_t zsda_taskqid;
+	boolean_t zsda_dispatched;
+	kmutex_t zsda_lock;
+	kcondvar_t zsda_cv;
 } zvol_set_prop_int_arg_t;
 
 /*
@@ -1982,6 +1986,7 @@ zvol_set_common_sync_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
 	char dsname[ZFS_MAX_DATASET_NAME_LEN];
 	zvol_task_t *task;
 	uint64_t prop;
+	taskqid_t id;
 
 	const char *prop_name = zfs_prop_to_name(zsda->zsda_prop);
 	dsl_dataset_name(ds, dsname);
@@ -2000,8 +2005,12 @@ zvol_set_common_sync_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
 	}
 	task->zt_value = prop;
 	strlcpy(task->zt_name1, dsname, sizeof (task->zt_name1));
-	(void) taskq_dispatch(dp->dp_spa->spa_zvol_taskq, zvol_task_cb,
-	    task, TQ_SLEEP);
+	id = taskq_dispatch(dp->dp_spa->spa_zvol_taskq, zvol_task_cb, task,
+	    TQ_SLEEP);
+	mutex_enter(&zsda->zsda_lock);
+	if (id != TASKQID_INVALID && id > zsda->zsda_taskqid)
+		zsda->zsda_taskqid = id;
+	mutex_exit(&zsda->zsda_lock);
 	return (0);
 }
 
@@ -2034,6 +2043,11 @@ zvol_set_common_sync(void *arg, dmu_tx_t *tx)
 	dmu_objset_find_dp(dp, dd->dd_object, zvol_set_common_sync_cb,
 	    zsda, DS_FIND_CHILDREN);
 
+	mutex_enter(&zsda->zsda_lock);
+	zsda->zsda_dispatched = TRUE;
+	cv_broadcast(&zsda->zsda_cv);
+	mutex_exit(&zsda->zsda_lock);
+
 	dsl_dir_rele(dd, FTAG);
 }
 
@@ -2042,14 +2056,38 @@ zvol_set_common(const char *ddname, zfs_prop_t prop, zprop_source_t source,
     uint64_t val)
 {
 	zvol_set_prop_int_arg_t zsda;
+	spa_t *spa;
+	int error;
 
 	zsda.zsda_name = ddname;
 	zsda.zsda_source = source;
 	zsda.zsda_value = val;
 	zsda.zsda_prop = prop;
+	zsda.zsda_taskqid = TASKQID_INVALID;
+	zsda.zsda_dispatched = FALSE;
+	mutex_init(&zsda.zsda_lock, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&zsda.zsda_cv, NULL, CV_DEFAULT, NULL);
 
-	return (dsl_sync_task(ddname, zvol_set_common_check,
-	    zvol_set_common_sync, &zsda, 0, ZFS_SPACE_CHECK_NONE));
+	error = spa_open(ddname, &spa, FTAG);
+	if (error != 0)
+		goto out;
+	error = dsl_sync_task(ddname, zvol_set_common_check,
+	    zvol_set_common_sync, &zsda, 0, ZFS_SPACE_CHECK_NONE);
+	if (error == 0) {
+		mutex_enter(&zsda.zsda_lock);
+		while (!zsda.zsda_dispatched)
+			cv_wait(&zsda.zsda_cv, &zsda.zsda_lock);
+		mutex_exit(&zsda.zsda_lock);
+
+		if (zsda.zsda_taskqid != TASKQID_INVALID)
+			taskq_wait_outstanding(spa->spa_zvol_taskq,
+			    zsda.zsda_taskqid);
+	}
+	spa_close(spa, FTAG);
+out:
+	cv_destroy(&zsda.zsda_cv);
+	mutex_destroy(&zsda.zsda_lock);
+	return (error);
 }
 
 void