zvol: ensure device minors are properly cleaned up

include/sys/zvol_impl.h

@@ -18,22 +18,19 @@
  *
  * CDDL HEADER END
  */
+/*
+ * Copyright (c) 2024, Klara, Inc.
+ */
 
 #ifndef	_SYS_ZVOL_IMPL_H
 #define	_SYS_ZVOL_IMPL_H
 
 #include <sys/zfs_context.h>
 
-#define	ZVOL_RDONLY	0x1
-/*
- * Whether the zvol has been written to (as opposed to ZVOL_RDONLY, which
- * specifies whether or not the zvol _can_ be written to)
- */
-#define	ZVOL_WRITTEN_TO	0x2
-
-#define	ZVOL_DUMPIFIED	0x4
-
-#define	ZVOL_EXCL	0x8
+#define	ZVOL_RDONLY	(1<<0)	/* zvol is readonly (writes rejected) */
+#define	ZVOL_WRITTEN_TO	(1<<1)	/* zvol has been written to (needs flush) */
+#define	ZVOL_EXCL	(1<<2)	/* zvol has O_EXCL client right now */
+#define	ZVOL_REMOVING	(1<<3)	/* zvol waiting to remove minor */
 
 /*
  * The in-core state of each volume.
@@ -57,6 +54,7 @@ typedef struct zvol_state {
 	kmutex_t		zv_state_lock;	/* protects zvol_state_t */
 	atomic_t		zv_suspend_ref;	/* refcount for suspend */
 	krwlock_t		zv_suspend_lock;	/* suspend lock */
+	kcondvar_t		zv_removing_cv;	/* ready to remove minor */
 	struct zvol_state_os	*zv_zso;	/* private platform state */
 	boolean_t		zv_threading;	/* volthreading property */
 } zvol_state_t;

module/os/freebsd/zfs/zvol_os.c

@@ -30,6 +30,7 @@
  * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  * Copyright (c) 2014 Integros [integros.com]
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 /* Portions Copyright 2011 Martin Matuska <[email protected]> */
@@ -250,7 +251,7 @@ zvol_geom_open(struct g_provider *pp, int flag, int count)
 	}
 
 	mutex_enter(&zv->zv_state_lock);
-	if (zv->zv_zso->zso_dying) {
+	if (zv->zv_zso->zso_dying || zv->zv_flags & ZVOL_REMOVING) {
 		rw_exit(&zvol_state_lock);
 		err = SET_ERROR(ENXIO);
 		goto out_zv_locked;
@@ -683,6 +684,11 @@ zvol_geom_bio_strategy(struct bio *bp)
 
 	rw_enter(&zv->zv_suspend_lock, ZVOL_RW_READER);
 
+	if (zv->zv_flags & ZVOL_REMOVING) {
+		error = SET_ERROR(ENXIO);
+		goto resume;
+	}
+
 	switch (bp->bio_cmd) {
 	case BIO_READ:
 		doread = B_TRUE;
@@ -1362,6 +1368,7 @@ zvol_os_free(zvol_state_t *zv)
 	}
 
 	mutex_destroy(&zv->zv_state_lock);
+	cv_destroy(&zv->zv_removing_cv);
 	dataset_kstats_destroy(&zv->zv_kstat);
 	kmem_free(zv->zv_zso, sizeof (struct zvol_state_os));
 	kmem_free(zv, sizeof (zvol_state_t));
@@ -1419,6 +1426,7 @@ zvol_os_create_minor(const char *name)
 	zv = kmem_zalloc(sizeof (*zv), KM_SLEEP);
 	zv->zv_hash = hash;
 	mutex_init(&zv->zv_state_lock, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&zv->zv_removing_cv, NULL, CV_DEFAULT, NULL);
 	zv->zv_zso = kmem_zalloc(sizeof (struct zvol_state_os), KM_SLEEP);
 	zv->zv_volmode = volmode;
 	if (zv->zv_volmode == ZFS_VOLMODE_GEOM) {

module/os/linux/zfs/zvol_os.c

@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 #include <sys/dataset_kstats.h>
@@ -526,6 +527,11 @@ zvol_request_impl(zvol_state_t *zv, struct bio *bio, struct request *rq,
 	uint64_t size = io_size(bio, rq);
 	int rw = io_data_dir(bio, rq);
 
+	if (unlikely(zv->zv_flags & ZVOL_REMOVING)) {
+		END_IO(zv, bio, rq, -SET_ERROR(ENXIO));
+		goto out;
+	}
+
 	if (zvol_request_sync || zv->zv_threading == B_FALSE)
 		force_sync = 1;
 
@@ -730,10 +736,17 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 #endif
 	if (zv == NULL) {
 		rw_exit(&zvol_state_lock);
-		return (SET_ERROR(-ENXIO));
+		return (-SET_ERROR(ENXIO));
 	}
 
 	mutex_enter(&zv->zv_state_lock);
+
+	if (unlikely(zv->zv_flags & ZVOL_REMOVING)) {
+		mutex_exit(&zv->zv_state_lock);
+		rw_exit(&zvol_state_lock);
+		return (-SET_ERROR(ENXIO));
+	}
+
 	/*
 	 * Make sure zvol is not suspended during first open
 	 * (hold zv_suspend_lock) and respect proper lock acquisition
@@ -795,10 +808,10 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 
 #ifdef HAVE_BLKDEV_GET_ERESTARTSYS
 				schedule();
-				return (SET_ERROR(-ERESTARTSYS));
+				return (-SET_ERROR(ERESTARTSYS));
 #else
 				if ((gethrtime() - start) > timeout)
-					return (SET_ERROR(-ERESTARTSYS));
+					return (-SET_ERROR(ERESTARTSYS));
 
 				schedule_timeout_interruptible(
 					MSEC_TO_TICK(10));
@@ -821,7 +834,7 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 			if (zv->zv_open_count == 0)
 				zvol_last_close(zv);
 
-			error = SET_ERROR(-EROFS);
+			error = -SET_ERROR(EROFS);
 		} else {
 			zv->zv_open_count++;
 		}
@@ -1313,6 +1326,7 @@ zvol_alloc(dev_t dev, const char *name)
 
 	list_link_init(&zv->zv_next);
 	mutex_init(&zv->zv_state_lock, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&zv->zv_removing_cv, NULL, CV_DEFAULT, NULL);
 
 #ifdef HAVE_BLK_MQ
 	zv->zv_zso->use_blk_mq = zvol_use_blk_mq;
@@ -1438,6 +1452,7 @@ zvol_os_free(zvol_state_t *zv)
 	ida_simple_remove(&zvol_ida,
 	    MINOR(zv->zv_zso->zvo_dev) >> ZVOL_MINOR_BITS);
 
+	cv_destroy(&zv->zv_removing_cv);
 	mutex_destroy(&zv->zv_state_lock);
 	dataset_kstats_destroy(&zv->zv_kstat);
 

module/zfs/zvol.c

@@ -37,6 +37,7 @@
  * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2016 Actifio, Inc. All rights reserved.
  * Copyright (c) 2012, 2019 by Delphix. All rights reserved.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 /*
@@ -894,6 +895,9 @@ zvol_resume(zvol_state_t *zv)
 	 */
 	atomic_dec(&zv->zv_suspend_ref);
 
+	if (zv->zv_flags & ZVOL_REMOVING)
+		cv_broadcast(&zv->zv_removing_cv);
+
 	return (SET_ERROR(error));
 }
 
@@ -929,6 +933,9 @@ zvol_last_close(zvol_state_t *zv)
 	ASSERT(RW_READ_HELD(&zv->zv_suspend_lock));
 	ASSERT(MUTEX_HELD(&zv->zv_state_lock));
 
+	if (zv->zv_flags & ZVOL_REMOVING)
+		cv_broadcast(&zv->zv_removing_cv);
+
 	zvol_shutdown_zv(zv);
 
 	dmu_objset_disown(zv->zv_objset, 1, zv);
@@ -1221,6 +1228,41 @@ zvol_create_minor(const char *name)
  * Remove minors for specified dataset including children and snapshots.
  */
 
+/*
+ * Remove the minor for a given zvol. This will do it all:
+ *  - flag the zvol for removal, so new requests are rejected
+ *  - wait until outstanding requests are completed
+ *  - remove it from lists
+ *  - free it
+ * It's also usable as a taskq task, and smells nice too.
+ */
+static void
+zvol_remove_minor_task(void *arg)
+{
+	zvol_state_t *zv = (zvol_state_t *)arg;
+
+	ASSERT(!RW_LOCK_HELD(&zvol_state_lock));
+	ASSERT(!MUTEX_HELD(&zv->zv_state_lock));
+
+	mutex_enter(&zv->zv_state_lock);
+	while (zv->zv_open_count > 0 || atomic_read(&zv->zv_suspend_ref)) {
+		zv->zv_flags |= ZVOL_REMOVING;
+		cv_wait(&zv->zv_removing_cv, &zv->zv_state_lock);
+	}
+	mutex_exit(&zv->zv_state_lock);
+
+	rw_enter(&zvol_state_lock, RW_WRITER);
+	mutex_enter(&zv->zv_state_lock);
+
+	zvol_remove(zv);
+	zvol_os_clear_private(zv);
+
+	mutex_exit(&zv->zv_state_lock);
+	rw_exit(&zvol_state_lock);
+
+	zvol_os_free(zv);
+}
+
 static void
 zvol_free_task(void *arg)
 {
@@ -1233,11 +1275,13 @@ zvol_remove_minors_impl(const char *name)
 	zvol_state_t *zv, *zv_next;
 	int namelen = ((name) ? strlen(name) : 0);
 	taskqid_t t;
-	list_t free_list;
+	list_t delay_list, free_list;
 
 	if (zvol_inhibit_dev)
 		return;
 
+	list_create(&delay_list, sizeof (zvol_state_t),
+	    offsetof(zvol_state_t, zv_next));
 	list_create(&free_list, sizeof (zvol_state_t),
 	    offsetof(zvol_state_t, zv_next));
 
@@ -1256,9 +1300,24 @@ zvol_remove_minors_impl(const char *name)
 			 * one is currently using this zv
 			 */
 
-			/* If in use, leave alone */
+			/*
+			 * If in use, try to throw everyone off and try again
+			 * later.
+			 */
 			if (zv->zv_open_count > 0 ||
 			    atomic_read(&zv->zv_suspend_ref)) {
+				zv->zv_flags |= ZVOL_REMOVING;
+				t = taskq_dispatch(
+				    zv->zv_objset->os_spa->spa_zvol_taskq,
+				    zvol_remove_minor_task, zv, TQ_SLEEP);
+				if (t == TASKQID_INVALID) {
+					/*
+					 * Couldn't create the task, so we'll
+					 * do it in place once the loop is
+					 * finished.
+					 */
+					list_insert_head(&delay_list, zv);
+				}
 				mutex_exit(&zv->zv_state_lock);
 				continue;
 			}
@@ -1285,7 +1344,11 @@ zvol_remove_minors_impl(const char *name)
 	}
 	rw_exit(&zvol_state_lock);
 
-	/* Drop zvol_state_lock before calling zvol_free() */
+	/* Wait for zvols that we couldn't create a remove task for */
+	while ((zv = list_remove_head(&delay_list)) != NULL)
+		zvol_remove_minor_task(zv);
+
+	/* Free any that we couldn't free in parallel earlier */
 	while ((zv = list_remove_head(&free_list)) != NULL)
 		zvol_os_free(zv);
 }
@@ -1305,33 +1368,38 @@ zvol_remove_minor_impl(const char *name)
 		zv_next = list_next(&zvol_state_list, zv);
 
 		mutex_enter(&zv->zv_state_lock);
-		if (strcmp(zv->zv_name, name) == 0) {
-			/*
-			 * By holding zv_state_lock here, we guarantee that no
-			 * one is currently using this zv
-			 */
+		if (strcmp(zv->zv_name, name) == 0)
+			/* Found, leave the the loop with zv_lock held */
+			break;
+		mutex_exit(&zv->zv_state_lock);
+	}
 
-			/* If in use, leave alone */
-			if (zv->zv_open_count > 0 ||
-			    atomic_read(&zv->zv_suspend_ref)) {
-				mutex_exit(&zv->zv_state_lock);
-				continue;
-			}
-			zvol_remove(zv);
+	if (zv == NULL) {
+		rw_exit(&zvol_state_lock);
+		return;
+	}
 
-			zvol_os_clear_private(zv);
-			mutex_exit(&zv->zv_state_lock);
-			break;
-		} else {
-			mutex_exit(&zv->zv_state_lock);
-		}
+	ASSERT(MUTEX_HELD(&zv->zv_state_lock));
+
+	if (zv->zv_open_count > 0 || atomic_read(&zv->zv_suspend_ref)) {
+		/*
+		 * In use, so try to throw everyone off, then wait
+		 * until finished.
+		 */
+		zv->zv_flags |= ZVOL_REMOVING;
+		mutex_exit(&zv->zv_state_lock);
+		rw_exit(&zvol_state_lock);
+		zvol_remove_minor_task(zv);
+		return;
 	}
 
-	/* Drop zvol_state_lock before calling zvol_free() */
+	zvol_remove(zv);
+	zvol_os_clear_private(zv);
+
+	mutex_exit(&zv->zv_state_lock);
 	rw_exit(&zvol_state_lock);
 
-	if (zv != NULL)
-		zvol_os_free(zv);
+	zvol_os_free(zv);
 }
 
 /*

tests/test-runner/bin/zts-report.py.in

@@ -350,10 +350,6 @@ elif sys.platform.startswith('linux'):
         'mmp/mmp_active_import': ['FAIL', known_reason],
         'mmp/mmp_exported_import': ['FAIL', known_reason],
         'mmp/mmp_inactive_import': ['FAIL', known_reason],
-        'zvol/zvol_misc/zvol_misc_fua': ['SKIP', 14872],
-        'zvol/zvol_misc/zvol_misc_snapdev': ['FAIL', 12621],
-        'zvol/zvol_misc/zvol_misc_trim': ['SKIP', 14872],
-        'zvol/zvol_misc/zvol_misc_volmode': ['FAIL', known_reason],
     })
 
 # Not all Github actions runners have scsi_debug module, so we may skip

tests/zfs-tests/tests/functional/zvol/zvol_misc/zvol_misc_fua.ksh

@@ -45,15 +45,6 @@ fi
 
 if ! is_linux ; then
 	log_unsupported "Only linux supports dd with oflag=dsync for FUA writes"
-else
-	if [[ $(linux_version) -gt $(linux_version "6.2") ]]; then
-		log_unsupported "Disabled while issue #14872 is being worked"
-	fi
-
-	# Disabled for the CentOS 9 kernel
-	if [[ $(linux_version) -eq $(linux_version "5.14") ]]; then
-		log_unsupported "Disabled while issue #14872 is being worked"
-	fi
 fi
 
 typeset datafile1="$(mktemp zvol_misc_fua1.XXXXXX)"

tests/zfs-tests/tests/functional/zvol/zvol_misc/zvol_misc_trim.ksh

@@ -44,15 +44,6 @@
 verify_runnable "global"
 
 if is_linux ; then
-	if [[ $(linux_version) -gt $(linux_version "6.2") ]]; then
-		log_unsupported "Disabled while issue #14872 is being worked"
-	fi
-
-	# Disabled for the CentOS 9 kernel
-	if [[ $(linux_version) -eq $(linux_version "5.14") ]]; then
-		log_unsupported "Disabled while issue #14872 is being worked"
-	fi
-
 	# We need '--force' here since the prior tests may leave a filesystem
 	# on the zvol, and blkdiscard will see that filesystem and print a
 	# warning unless you force it.