From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Fri, 6 Dec 2013 22:20:22 +0000 (-0800)
Subject: Remove ZFC_IOC_*_MINOR ioctl()s
X-Git-Tag: zfs-0.6.3~145
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ba6a24026c;p=zfs

Remove ZFC_IOC_*_MINOR ioctl()s

Early versions of ZFS coordinated the creation and destruction
of device minors from userspace.  This was inherently racy and
in late 2009 these ioctl()s were removed leaving everything up
to the kernel.  This significantly simplified the code.

However, we never picked up these changes in ZoL since we'd
already significantly adjusted this code for Linux.  This patch
aims to rectify that by finally removing ZFC_IOC_*_MINOR ioctl()s
and moving all the functionality down in to the kernel.  Since
this cleanup will change the kernel/user ABI it's being done
in the same tag as the previous libzfs_core ABI changes.  This
will minimize, but not eliminate, the disruption to end users.

Once merged ZoL, Illumos, and FreeBSD will basically be back
in sync in regards to handling ZVOLs in the common code.  While
each platform must have its own custom zvol.c implemenation the
interfaces provided are consistent.

NOTES:

1) This patch introduces one subtle change in behavior which
   could not be easily avoided.  Prior to this change callers
   of 'zfs create -V ...' were guaranteed that upon exit the
   /dev/zvol/ block device link would be created or an error
   returned.  That's no longer the case.  The utilities will no
   longer block waiting for the symlink to be created.  Callers
   are now responsible for blocking, this is why a 'udev_wait'
   call was added to the 'label' function in scripts/common.sh.

2) The read-only behavior of a ZVOL now solely depends on if
   the ZVOL_RDONLY bit is set in zv->zv_flags.  The redundant
   policy setting in the gendisk structure was removed.  This
   both simplifies the code and allows us to safely leverage
   set_disk_ro() to issue a KOBJ_CHANGE uevent.  See the
   comment in the code for futher details on this.

3) Because __zvol_create_minor() and zvol_alloc() may now be
   called in a sync task they must use KM_PUSHPAGE.

References:
  illumos/illumos-gate@681d9761e8516a7dc5ab6589e2dfe717777e1123

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #1969
---

diff --git a/include/libzfs_impl.h b/include/libzfs_impl.h
index 7daf8348b..5502455e0 100644
--- a/include/libzfs_impl.h
+++ b/include/libzfs_impl.h
@@ -193,8 +193,6 @@ zfs_handle_t *make_dataset_handle(libzfs_handle_t *, const char *);
 
 int zpool_open_silent(libzfs_handle_t *, const char *, zpool_handle_t **);
 
-int zvol_create_link(libzfs_handle_t *, const char *);
-int zvol_remove_link(libzfs_handle_t *, const char *);
 boolean_t zpool_name_valid(libzfs_handle_t *, boolean_t, const char *);
 
 int zfs_validate_name(libzfs_handle_t *hdl, const char *path, int type,
diff --git a/include/sys/fs/zfs.h b/include/sys/fs/zfs.h
index e945b40a9..08076bc09 100644
--- a/include/sys/fs/zfs.h
+++ b/include/sys/fs/zfs.h
@@ -793,8 +793,6 @@ typedef enum zfs_ioc {
 	ZFS_IOC_DATASET_LIST_NEXT,
 	ZFS_IOC_SNAPSHOT_LIST_NEXT,
 	ZFS_IOC_SET_PROP,
-	ZFS_IOC_CREATE_MINOR,
-	ZFS_IOC_REMOVE_MINOR,
 	ZFS_IOC_CREATE,
 	ZFS_IOC_DESTROY,
 	ZFS_IOC_ROLLBACK,
diff --git a/include/sys/zfs_ioctl.h b/include/sys/zfs_ioctl.h
index 4a717b7d1..52557d210 100644
--- a/include/sys/zfs_ioctl.h
+++ b/include/sys/zfs_ioctl.h
@@ -359,6 +359,8 @@ extern int zfs_secpolicy_destroy_perms(const char *name, cred_t *cr);
 extern int zfs_unmount_snap(const char *);
 extern void zfs_destroy_unmount_origin(const char *);
 
+extern boolean_t dataset_name_hidden(const char *name);
+
 enum zfsdev_state_type {
 	ZST_ONEXIT,
 	ZST_ZEVENT,
diff --git a/include/sys/zvol.h b/include/sys/zvol.h
index 640538c2c..04e099657 100644
--- a/include/sys/zvol.h
+++ b/include/sys/zvol.h
@@ -38,10 +38,11 @@ extern int zvol_check_volblocksize(uint64_t volblocksize);
 extern int zvol_get_stats(objset_t *os, nvlist_t *nv);
 extern boolean_t zvol_is_zvol(const char *);
 extern void zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx);
-extern int zvol_create_minor(const char *);
-extern int zvol_create_minors(char *);
-extern int zvol_remove_minor(const char *);
-extern void zvol_remove_minors(const char *);
+extern int zvol_create_minor(const char *name);
+extern int zvol_create_minors(const char *name);
+extern int zvol_remove_minor(const char *name);
+extern void zvol_remove_minors(const char *name);
+extern void zvol_rename_minors(const char *oldname, const char *newname);
 extern int zvol_set_volsize(const char *, uint64_t);
 extern int zvol_set_volblocksize(const char *, uint64_t);
 extern int zvol_set_snapdev(const char *, uint64_t);
diff --git a/lib/libzfs/libzfs_changelist.c b/lib/libzfs/libzfs_changelist.c
index 3a83e2d71..0bcfc0423 100644
--- a/lib/libzfs/libzfs_changelist.c
+++ b/lib/libzfs/libzfs_changelist.c
@@ -291,30 +291,22 @@ changelist_rename(prop_changelist_t *clp, const char *src, const char *dst)
 
 	for (cn = uu_list_first(clp->cl_list); cn != NULL;
 	    cn = uu_list_next(clp->cl_list, cn)) {
-		zfs_handle_t *hdl;
-
-		hdl = cn->cn_handle;
-
 		/*
 		 * Do not rename a clone that's not in the source hierarchy.
 		 */
-		if (!isa_child_of(hdl->zfs_name, src))
+		if (!isa_child_of(cn->cn_handle->zfs_name, src))
 			continue;
 
 		/*
 		 * Destroy the previous mountpoint if needed.
 		 */
-		remove_mountpoint(hdl);
+		remove_mountpoint(cn->cn_handle);
 
 		(void) strlcpy(newname, dst, sizeof (newname));
-		(void) strcat(newname, hdl->zfs_name + strlen(src));
-
-		if (ZFS_IS_VOLUME(hdl)) {
-			(void) zvol_remove_link(hdl->zfs_hdl, hdl->zfs_name);
-			(void) zvol_create_link(hdl->zfs_hdl, newname);
-		}
+		(void) strcat(newname, cn->cn_handle->zfs_name + strlen(src));
 
-		(void) strlcpy(hdl->zfs_name, newname, sizeof (hdl->zfs_name));
+		(void) strlcpy(cn->cn_handle->zfs_name, newname,
+		    sizeof (cn->cn_handle->zfs_name));
 	}
 }
 
diff --git a/lib/libzfs/libzfs_dataset.c b/lib/libzfs/libzfs_dataset.c
index 9810b2e2d..90b6572b1 100644
--- a/lib/libzfs/libzfs_dataset.c
+++ b/lib/libzfs/libzfs_dataset.c
@@ -63,7 +63,6 @@
 #include "libzfs_impl.h"
 #include "zfs_deleg.h"
 
-static int zvol_create_link_common(libzfs_handle_t *, const char *, int);
 static int userquota_propname_decode(const char *propname, boolean_t zoned,
     zfs_userquota_prop_t *typep, char *domain, int domainlen, uint64_t *ridp);
 
@@ -418,8 +417,7 @@ make_dataset_handle_common(zfs_handle_t *zhp, zfs_cmd_t *zc)
 	else if (zhp->zfs_dmustats.dds_type == DMU_OST_ZFS)
 		zhp->zfs_head_type = ZFS_TYPE_FILESYSTEM;
 	else if (zhp->zfs_dmustats.dds_type == DMU_OST_OTHER)
-		return (-1); /* zpios' and other testing datasets are
-		                of this type, ignore if encountered */
+		return (-1);
 	else
 		abort();
 
@@ -2121,7 +2119,8 @@ zfs_prop_get(zfs_handle_t *zhp, zfs_prop_t prop, char *propbuf, size_t proplen,
 			    localtime_r(&time, &t) == NULL ||
 			    strftime(propbuf, proplen, "%a %b %e %k:%M %Y",
 			    &t) == 0)
-				(void) snprintf(propbuf, proplen, "%llu", (u_longlong_t) val);
+				(void) snprintf(propbuf, proplen, "%llu",
+				    (u_longlong_t) val);
 		}
 		break;
 
@@ -2628,7 +2627,7 @@ zfs_prop_get_userquota(zfs_handle_t *zhp, const char *propname,
 
 	if (literal) {
 		(void) snprintf(propbuf, proplen, "%llu",
-			       (u_longlong_t)propvalue);
+		    (u_longlong_t)propvalue);
 	} else if (propvalue == 0 &&
 	    (type == ZFS_PROP_USERQUOTA || type == ZFS_PROP_GROUPQUOTA)) {
 		(void) strlcpy(propbuf, "none", proplen);
@@ -2685,7 +2684,8 @@ zfs_prop_get_written(zfs_handle_t *zhp, const char *propname,
 		return (err);
 
 	if (literal) {
-		(void) snprintf(propbuf, proplen, "%llu", (long long unsigned int)propvalue);
+		(void) snprintf(propbuf, proplen, "%llu",
+		    (u_longlong_t)propvalue);
 	} else {
 		zfs_nicenum(propvalue, propbuf, proplen);
 	}
@@ -3056,17 +3056,6 @@ zfs_create(libzfs_handle_t *hdl, const char *path, zfs_type_t type,
 	ret = lzc_create(path, ost, props);
 	nvlist_free(props);
 
-	if (ret == 0 && type == ZFS_TYPE_VOLUME) {
-		ret = zvol_create_link(hdl, path);
-		if (ret) {
-			(void) zfs_standard_error(hdl, errno,
-			    dgettext(TEXT_DOMAIN,
-			    "Volume successfully created, but device links "
-			    "were not created"));
-			return (-1);
-		}
-	}
-
 	/* check for failure */
 	if (ret != 0) {
 		char parent[ZFS_MAXNAMELEN];
@@ -3128,9 +3117,6 @@ zfs_destroy(zfs_handle_t *zhp, boolean_t defer)
 	(void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));
 
 	if (ZFS_IS_VOLUME(zhp)) {
-		if (zvol_remove_link(zhp->zfs_hdl, zhp->zfs_name) != 0)
-			return (-1);
-
 		zc.zc_objset_type = DMU_OST_ZVOL;
 	} else {
 		zc.zc_objset_type = DMU_OST_ZFS;
@@ -3167,15 +3153,6 @@ zfs_check_snap_cb(zfs_handle_t *zhp, void *arg)
 	if (lzc_exists(name))
 		verify(nvlist_add_boolean(dd->nvl, name) == 0);
 
-	if (zhp->zfs_type == ZFS_TYPE_VOLUME) {
-		(void) zvol_remove_link(zhp->zfs_hdl, name);
-		/*
-		 * NB: this is simply a best-effort.  We don't want to
-		 * return an error, because then we wouldn't visit all
-		 * the volumes.
-		 */
-	}
-
 	rv = zfs_iter_filesystems(zhp, zfs_check_snap_cb, dd);
 	zfs_close(zhp);
 	return (rv);
@@ -3320,70 +3297,11 @@ zfs_clone(zfs_handle_t *zhp, const char *target, nvlist_t *props)
 			return (zfs_standard_error(zhp->zfs_hdl, errno,
 			    errbuf));
 		}
-	} else if (ZFS_IS_VOLUME(zhp)) {
-		ret = zvol_create_link(zhp->zfs_hdl, target);
 	}
 
 	return (ret);
 }
 
-typedef struct promote_data {
-	char cb_mountpoint[MAXPATHLEN];
-	const char *cb_target;
-	const char *cb_errbuf;
-	uint64_t cb_pivot_txg;
-} promote_data_t;
-
-static int
-promote_snap_cb(zfs_handle_t *zhp, void *data)
-{
-	promote_data_t *pd = data;
-	zfs_handle_t *szhp;
-	char snapname[MAXPATHLEN];
-	int rv = 0;
-
-	/* We don't care about snapshots after the pivot point */
-	if (zfs_prop_get_int(zhp, ZFS_PROP_CREATETXG) > pd->cb_pivot_txg) {
-		zfs_close(zhp);
-		return (0);
-	}
-
-	/* Remove the device link if it's a zvol. */
-	if (ZFS_IS_VOLUME(zhp))
-		(void) zvol_remove_link(zhp->zfs_hdl, zhp->zfs_name);
-
-	/* Check for conflicting names */
-	(void) strlcpy(snapname, pd->cb_target, sizeof (snapname));
-	(void) strlcat(snapname, strchr(zhp->zfs_name, '@'), sizeof (snapname));
-	szhp = make_dataset_handle(zhp->zfs_hdl, snapname);
-	if (szhp != NULL) {
-		zfs_close(szhp);
-		zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
-		    "snapshot name '%s' from origin \n"
-		    "conflicts with '%s' from target"),
-		    zhp->zfs_name, snapname);
-		rv = zfs_error(zhp->zfs_hdl, EZFS_EXISTS, pd->cb_errbuf);
-	}
-	zfs_close(zhp);
-	return (rv);
-}
-
-static int
-promote_snap_done_cb(zfs_handle_t *zhp, void *data)
-{
-	promote_data_t *pd = data;
-
-	/* We don't care about snapshots after the pivot point */
-	if (zfs_prop_get_int(zhp, ZFS_PROP_CREATETXG) <= pd->cb_pivot_txg) {
-		/* Create the device link if it's a zvol. */
-		if (ZFS_IS_VOLUME(zhp))
-			(void) zvol_create_link(zhp->zfs_hdl, zhp->zfs_name);
-	}
-
-	zfs_close(zhp);
-	return (0);
-}
-
 /*
  * Promotes the given clone fs to be the clone parent.
  */
@@ -3393,10 +3311,7 @@ zfs_promote(zfs_handle_t *zhp)
 	libzfs_handle_t *hdl = zhp->zfs_hdl;
 	zfs_cmd_t zc = {"\0"};
 	char parent[MAXPATHLEN];
-	char *cp;
 	int ret;
-	zfs_handle_t *pzhp;
-	promote_data_t pd;
 	char errbuf[1024];
 
 	(void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
@@ -3414,29 +3329,7 @@ zfs_promote(zfs_handle_t *zhp)
 		    "not a cloned filesystem"));
 		return (zfs_error(hdl, EZFS_BADTYPE, errbuf));
 	}
-	cp = strchr(parent, '@');
-	*cp = '\0';
 
-	/* Walk the snapshots we will be moving */
-	pzhp = zfs_open(hdl, zhp->zfs_dmustats.dds_origin, ZFS_TYPE_SNAPSHOT);
-	if (pzhp == NULL)
-		return (-1);
-	pd.cb_pivot_txg = zfs_prop_get_int(pzhp, ZFS_PROP_CREATETXG);
-	zfs_close(pzhp);
-	pd.cb_target = zhp->zfs_name;
-	pd.cb_errbuf = errbuf;
-	pzhp = zfs_open(hdl, parent, ZFS_TYPE_DATASET);
-	if (pzhp == NULL)
-		return (-1);
-	(void) zfs_prop_get(pzhp, ZFS_PROP_MOUNTPOINT, pd.cb_mountpoint,
-	    sizeof (pd.cb_mountpoint), NULL, NULL, 0, FALSE);
-	ret = zfs_iter_snapshots(pzhp, B_FALSE, promote_snap_cb, &pd);
-	if (ret != 0) {
-		zfs_close(pzhp);
-		return (-1);
-	}
-
-	/* issue the ioctl */
 	(void) strlcpy(zc.zc_value, zhp->zfs_dmustats.dds_origin,
 	    sizeof (zc.zc_value));
 	(void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));
@@ -3445,17 +3338,9 @@ zfs_promote(zfs_handle_t *zhp)
 	if (ret != 0) {
 		int save_errno = errno;
 
-		(void) zfs_iter_snapshots(pzhp, B_FALSE, promote_snap_done_cb,
-		    &pd);
-		zfs_close(pzhp);
-
 		switch (save_errno) {
 		case EEXIST:
-			/*
-			 * There is a conflicting snapshot name.  We
-			 * should have caught this above, but they could
-			 * have renamed something in the mean time.
-			 */
+			/* There is a conflicting snapshot name. */
 			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
 			    "conflicting snapshot '%s' from parent '%s'"),
 			    zc.zc_string, parent);
@@ -3464,45 +3349,7 @@ zfs_promote(zfs_handle_t *zhp)
 		default:
 			return (zfs_standard_error(hdl, save_errno, errbuf));
 		}
-	} else {
-		(void) zfs_iter_snapshots(zhp, B_FALSE, promote_snap_done_cb,
-		    &pd);
 	}
-
-	zfs_close(pzhp);
-	return (ret);
-}
-
-struct createdata {
-	const char *cd_snapname;
-	int cd_ifexists;
-};
-
-static int
-zfs_create_link_cb(zfs_handle_t *zhp, void *arg)
-{
-	struct createdata *cd = arg;
-	int ret;
-
-	if (zhp->zfs_type == ZFS_TYPE_VOLUME) {
-		char name[MAXPATHLEN];
-
-		(void) strlcpy(name, zhp->zfs_name, sizeof (name));
-		(void) strlcat(name, "@", sizeof (name));
-		(void) strlcat(name, cd->cd_snapname, sizeof (name));
-		(void) zvol_create_link_common(zhp->zfs_hdl, name,
-		    cd->cd_ifexists);
-		/*
-		 * NB: this is simply a best-effort.  We don't want to
-		 * return an error, because then we wouldn't visit all
-		 * the volumes.
-		 */
-	}
-
-	ret = zfs_iter_filesystems(zhp, zfs_create_link_cb, cd);
-
-	zfs_close(zhp);
-
 	return (ret);
 }
 
@@ -3593,31 +3440,6 @@ zfs_snapshot_nvl(libzfs_handle_t *hdl, nvlist_t *snaps, nvlist_t *props)
 				(void) zfs_standard_error(hdl, ret, errbuf);
 			}
 		}
-	} else {
-		zfs_handle_t *zhp;
-		int linktries = 0, linkok = 0, linkfail = 0;
-		nvpair_t *snap;
-
-		for (snap = nvlist_next_nvpair(snaps, NULL); snap != NULL;
-		    snap = nvlist_next_nvpair(snaps, snap)) {
-			char *cp, *snapname;
-
-			snapname = nvpair_name(snap);
-			cp = strchr(snapname, '@');
-			*cp = '\0';
-
-			if ((zhp = zfs_open(hdl, snapname, ZFS_TYPE_FILESYSTEM |
-				ZFS_TYPE_VOLUME)) != NULL) {
-				if (zhp->zfs_type == ZFS_TYPE_VOLUME) {
-					++linktries;
-					*cp = '@';
-					if (zvol_create_link(zhp->zfs_hdl, nvpair_name(snap)))
-						++linkfail;
-					else
-						++linkok;
-				}
-			}
-		}
 	}
 
 	nvlist_free(props);
@@ -3641,7 +3463,7 @@ zfs_snapshot(libzfs_handle_t *hdl, const char *path, boolean_t recursive,
 
 	if (!zfs_validate_name(hdl, path, ZFS_TYPE_SNAPSHOT, B_TRUE))
 		return (zfs_error(hdl, EZFS_INVALIDNAME, errbuf));
- 
+
 	(void) strlcpy(fsname, path, sizeof (fsname));
 	cp = strchr(fsname, '@');
 	*cp = '\0';
@@ -3756,8 +3578,6 @@ zfs_rollback(zfs_handle_t *zhp, zfs_handle_t *snap, boolean_t force)
 	 */
 
 	if (zhp->zfs_type == ZFS_TYPE_VOLUME) {
-		if (zvol_remove_link(zhp->zfs_hdl, zhp->zfs_name) != 0)
-			return (-1);
 		if (zfs_which_resv_prop(zhp, &resv_prop) < 0)
 			return (-1);
 		old_volsize = zfs_prop_get_int(zhp, ZFS_PROP_VOLSIZE);
@@ -3788,10 +3608,6 @@ zfs_rollback(zfs_handle_t *zhp, zfs_handle_t *snap, boolean_t force)
 	 */
 	if ((zhp->zfs_type == ZFS_TYPE_VOLUME) &&
 	    (zhp = make_dataset_handle(zhp->zfs_hdl, zhp->zfs_name))) {
-		if ((err = zvol_create_link(zhp->zfs_hdl, zhp->zfs_name))) {
-			zfs_close(zhp);
-			return (err);
-		}
 		if (restore_resv) {
 			new_volsize = zfs_prop_get_int(zhp, ZFS_PROP_VOLSIZE);
 			if (old_volsize != new_volsize)
@@ -3905,7 +3721,6 @@ zfs_rename(zfs_handle_t *zhp, const char *target, boolean_t recursive,
 	}
 
 	if (recursive) {
-		struct destroydata dd;
 
 		parentname = zfs_strdup(zhp->zfs_hdl, zhp->zfs_name);
 		if (parentname == NULL) {
@@ -3920,15 +3735,6 @@ zfs_rename(zfs_handle_t *zhp, const char *target, boolean_t recursive,
 			goto error;
 		}
 
-		dd.snapname = delim + 1;
-
-		/* We remove any zvol links prior to renaming them */
-		verify(nvlist_alloc(&dd.nvl, NV_UNIQUE_NAME, 0) == 0);
-		ret = zfs_iter_filesystems(zhrp, zfs_check_snap_cb, &dd);
-		nvlist_free(dd.nvl);
-		if (ret) {
-			goto error;
-		}
 	} else {
 		if ((cl = changelist_gather(zhp, ZFS_PROP_NAME, 0,
 		    force_unmount ? MS_FORCE : 0)) == NULL)
@@ -3978,27 +3784,10 @@ zfs_rename(zfs_handle_t *zhp, const char *target, boolean_t recursive,
 		 * On failure, we still want to remount any filesystems that
 		 * were previously mounted, so we don't alter the system state.
 		 */
-		if (recursive) {
-			struct createdata cd;
-
-			/* only create links for datasets that had existed */
-			cd.cd_snapname = delim + 1;
-			cd.cd_ifexists = B_TRUE;
-			(void) zfs_iter_filesystems(zhrp, zfs_create_link_cb,
-			    &cd);
-		} else {
+		if (!recursive)
 			(void) changelist_postfix(cl);
-		}
 	} else {
-		if (recursive) {
-			struct createdata cd;
-
-			/* only create links for datasets that had existed */
-			cd.cd_snapname = strchr(target, '@') + 1;
-			cd.cd_ifexists = B_TRUE;
-			ret = zfs_iter_filesystems(zhrp, zfs_create_link_cb,
-			    &cd);
-		} else {
+		if (!recursive) {
 			changelist_rename(cl, zfs_get_name(zhp), target);
 			ret = changelist_postfix(cl);
 		}
@@ -4017,126 +3806,6 @@ error:
 	return (ret);
 }
 
-/*
- * Given a zvol dataset, issue the ioctl to create the appropriate minor node,
- * and wait briefly for udev to create the /dev link.
- */
-int
-zvol_create_link(libzfs_handle_t *hdl, const char *dataset)
-{
-	return (zvol_create_link_common(hdl, dataset, B_FALSE));
-}
-
-static int
-zvol_create_link_common(libzfs_handle_t *hdl, const char *dataset, int ifexists)
-{
-	zfs_cmd_t zc = {"\0"};
-	char path[MAXPATHLEN];
-	int error;
-
-	(void) strlcpy(zc.zc_name, dataset, sizeof (zc.zc_name));
-
-	/*
-	 * Issue the appropriate ioctl.
-	 */
-	if (ioctl(hdl->libzfs_fd, ZFS_IOC_CREATE_MINOR, &zc) != 0) {
-		switch (errno) {
-		case EEXIST:
-			/*
-			 * Silently ignore the case where the link already
-			 * exists.  This allows 'zfs volinit' to be run multiple
-			 * times without errors.
-			 */
-			return (0);
-
-		case ENODEV:
-			/*
-			 * snapdev set to hidden :
-			 *  device creation was not permitted (see zvol.c)
-			 *  ignore error quietly
-			 */
-			return (0);
-
-		case ENOENT:
-			/*
-			 * Dataset does not exist in the kernel.  If we
-			 * don't care (see zfs_rename), then ignore the
-			 * error quietly.
-			 */
-			if (ifexists) {
-				return (0);
-			}
-
-			/* FALLTHROUGH */
-
-		default:
-			return (zfs_standard_error_fmt(hdl, errno,
-			    dgettext(TEXT_DOMAIN, "cannot create device links "
-			    "for '%s'"), dataset));
-		}
-	}
-
-	/*
-	 * Wait for udev to create the device.
-	 */
-	(void) snprintf(path, sizeof (path), "%s/%s", ZVOL_DIR, dataset);
-	error = zpool_label_disk_wait(path, DISK_LABEL_WAIT);
-	if (error)
-		(void) printf(gettext("%s may not be immediately "
-		    "available\n"), path);
-
-	return (0);
-}
-
-/*
- * Remove a minor node for the given zvol and the associated /dev links.
- */
-int
-zvol_remove_link(libzfs_handle_t *hdl, const char *dataset)
-{
-	zfs_cmd_t zc = {"\0"};
-	int timeout = 3000; /* in milliseconds */
-	int error = 0;
-	int i;
-
-	(void) strlcpy(zc.zc_name, dataset, sizeof (zc.zc_name));
-
-	/*
-	 * Due to concurrent updates by udev the device may be reported as
-	 * busy.  In this case don't immediately fail.  Instead briefly delay
-	 * and retry the ioctl() which is now likely to succeed.  If unable
-	 * remove the link after timeout milliseconds return the failure.
-	 */
-	for (i = 0; i < timeout; i++) {
-		error = ioctl(hdl->libzfs_fd, ZFS_IOC_REMOVE_MINOR, &zc);
-		if (error && errno == EBUSY) {
-			usleep(1000);
-			continue;
-		} else {
-			break;
-		}
-	}
-
-	if (error) {
-		switch (errno) {
-		case ENXIO:
-			/*
-			 * Silently ignore the case where the link no longer
-			 * exists, so that 'zfs volfini' can be run multiple
-			 * times without errors.
-			 */
-			return (0);
-
-		default:
-			return (zfs_standard_error_fmt(hdl, errno,
-			    dgettext(TEXT_DOMAIN, "cannot remove device "
-			    "links for '%s': %s"), dataset, strerror(errno)));
-		}
-	}
-
-	return (0);
-}
-
 nvlist_t *
 zfs_get_user_props(zfs_handle_t *zhp)
 {
diff --git a/lib/libzfs/libzfs_sendrecv.c b/lib/libzfs/libzfs_sendrecv.c
index 9f366eea1..12ac9bdf9 100644
--- a/lib/libzfs/libzfs_sendrecv.c
+++ b/lib/libzfs/libzfs_sendrecv.c
@@ -2790,12 +2790,6 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 				return (-1);
 			}
 		}
-		if (!flags->dryrun && zhp->zfs_type == ZFS_TYPE_VOLUME &&
-		    zvol_remove_link(hdl, zhp->zfs_name) != 0) {
-			zfs_close(zhp);
-			zcmd_free_nvlists(&zc);
-			return (-1);
-		}
 		zfs_close(zhp);
 	} else {
 		/*
@@ -3001,10 +2995,6 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 		if (h != NULL) {
 			if (h->zfs_type == ZFS_TYPE_VOLUME) {
 				*cp = '@';
-				err = zvol_create_link(hdl, h->zfs_name);
-				if (err == 0 && ioctl_err == 0)
-					err = zvol_create_link(hdl,
-					    zc.zc_value);
 			} else if (newfs || stream_avl) {
 				/*
 				 * Track the first/top of hierarchy fs,
diff --git a/module/zfs/dsl_dataset.c b/module/zfs/dsl_dataset.c
index 9ee9508bf..52edbd3fa 100644
--- a/module/zfs/dsl_dataset.c
+++ b/module/zfs/dsl_dataset.c
@@ -1229,6 +1229,16 @@ dsl_dataset_snapshot(nvlist_t *snaps, nvlist_t *props, nvlist_t *errors)
 		fnvlist_free(suspended);
 	}
 
+#ifdef _KERNEL
+	if (error == 0) {
+		for (pair = nvlist_next_nvpair(snaps, NULL); pair != NULL;
+		     pair = nvlist_next_nvpair(snaps, pair)) {
+			char *snapname = nvpair_name(pair);
+			zvol_create_minors(snapname);
+		}
+	}
+#endif
+
 	return (error);
 }
 
@@ -1601,6 +1611,9 @@ static int
 dsl_dataset_rename_snapshot_sync_impl(dsl_pool_t *dp,
     dsl_dataset_t *hds, void *arg)
 {
+#ifdef _KERNEL
+	char *oldname, *newname;
+#endif
 	dsl_dataset_rename_snapshot_arg_t *ddrsa = arg;
 	dsl_dataset_t *ds;
 	uint64_t val;
@@ -1627,6 +1640,18 @@ dsl_dataset_rename_snapshot_sync_impl(dsl_pool_t *dp,
 	VERIFY0(zap_add(dp->dp_meta_objset, hds->ds_phys->ds_snapnames_zapobj,
 	    ds->ds_snapname, 8, 1, &ds->ds_object, tx));
 
+#ifdef _KERNEL
+	oldname = kmem_alloc(MAXPATHLEN, KM_PUSHPAGE);
+	newname = kmem_alloc(MAXPATHLEN, KM_PUSHPAGE);
+	snprintf(oldname, MAXPATHLEN, "%s@%s", ddrsa->ddrsa_fsname,
+	    ddrsa->ddrsa_oldsnapname);
+	snprintf(newname, MAXPATHLEN, "%s@%s", ddrsa->ddrsa_fsname,
+	    ddrsa->ddrsa_newsnapname);
+	zvol_rename_minors(oldname, newname);
+	kmem_free(newname, MAXPATHLEN);
+	kmem_free(oldname, MAXPATHLEN);
+#endif
+
 	dsl_dataset_rele(ds, FTAG);
 	return (0);
 }
diff --git a/module/zfs/dsl_dir.c b/module/zfs/dsl_dir.c
index 54a7dffb1..803a77c25 100644
--- a/module/zfs/dsl_dir.c
+++ b/module/zfs/dsl_dir.c
@@ -38,6 +38,7 @@
 #include <sys/zio.h>
 #include <sys/arc.h>
 #include <sys/sunddi.h>
+#include <sys/zvol.h>
 #include "zfs_namecheck.h"
 
 static uint64_t dsl_dir_space_towrite(dsl_dir_t *dd);
@@ -1302,6 +1303,10 @@ dsl_dir_rename_sync(void *arg, dmu_tx_t *tx)
 	VERIFY0(zap_add(mos, newparent->dd_phys->dd_child_dir_zapobj,
 	    dd->dd_myname, 8, 1, &dd->dd_object, tx));
 
+#ifdef _KERNEL
+	zvol_rename_minors(ddra->ddra_oldname, ddra->ddra_newname);
+#endif
+
 	dsl_prop_notify_all(dd);
 
 	dsl_dir_rele(newparent, FTAG);
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index ae82cb45b..9b084632f 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -2089,7 +2089,7 @@ zfs_ioc_objset_zplprops(zfs_cmd_t *zc)
 	return (err);
 }
 
-static boolean_t
+boolean_t
 dataset_name_hidden(const char *name)
 {
 	/*
@@ -2808,30 +2808,6 @@ zfs_ioc_pool_get_props(zfs_cmd_t *zc)
 	return (error);
 }
 
-/*
- * inputs:
- * zc_name              name of volume
- *
- * outputs:             none
- */
-static int
-zfs_ioc_create_minor(zfs_cmd_t *zc)
-{
-	return (zvol_create_minor(zc->zc_name));
-}
-
-/*
- * inputs:
- * zc_name              name of volume
- *
- * outputs:             none
- */
-static int
-zfs_ioc_remove_minor(zfs_cmd_t *zc)
-{
-	return (zvol_remove_minor(zc->zc_name));
-}
-
 /*
  * inputs:
  * zc_name		name of filesystem
@@ -3174,6 +3150,12 @@ zfs_ioc_create(const char *fsname, nvlist_t *innvl, nvlist_t *outnvl)
 		if (error != 0)
 			(void) dsl_destroy_head(fsname);
 	}
+
+#ifdef _KERNEL
+	if (error == 0 && type == DMU_OST_ZVOL)
+		zvol_create_minors(fsname);
+#endif
+
 	return (error);
 }
 
@@ -3216,6 +3198,12 @@ zfs_ioc_clone(const char *fsname, nvlist_t *innvl, nvlist_t *outnvl)
 		if (error != 0)
 			(void) dsl_destroy_head(fsname);
 	}
+
+#ifdef _KERNEL
+	if (error == 0)
+		zvol_create_minors(fsname);
+#endif
+
 	return (error);
 }
 
@@ -3276,6 +3264,12 @@ zfs_ioc_snapshot(const char *poolname, nvlist_t *innvl, nvlist_t *outnvl)
 	}
 
 	error = dsl_dataset_snapshot(snaps, props, outnvl);
+
+#ifdef _KERNEL
+	if (error == 0)
+		zvol_create_minors(poolname);
+#endif
+
 	return (error);
 }
 
@@ -3427,10 +3421,10 @@ zfs_ioc_destroy_snaps(const char *poolname, nvlist_t *innvl, nvlist_t *outnvl)
 		    (name[poollen] != '/' && name[poollen] != '@'))
 			return (SET_ERROR(EXDEV));
 
-		(void) zvol_remove_minor(name);
 		error = zfs_unmount_snap(name);
 		if (error != 0)
 			return (error);
+		(void) zvol_remove_minor(name);
 	}
 
 	return (dsl_destroy_snapshots_nvl(snaps, defer, outnvl));
@@ -3520,7 +3514,6 @@ zfs_ioc_rename(zfs_cmd_t *zc)
 {
 	boolean_t recursive = zc->zc_cookie & 1;
 	char *at;
-	int err;
 
 	zc->zc_value[sizeof (zc->zc_value) - 1] = '\0';
 	if (dataset_namecheck(zc->zc_value, NULL, NULL) != 0 ||
@@ -3550,12 +3543,7 @@ zfs_ioc_rename(zfs_cmd_t *zc)
 
 		return (error);
 	} else {
-		err = dsl_dir_rename(zc->zc_name, zc->zc_value);
-		if (!err && zc->zc_objset_type == DMU_OST_ZVOL) {
-			(void) zvol_remove_minor(zc->zc_name);
-			(void) zvol_create_minor(zc->zc_value);
-		}
-		return (err);
+		return (dsl_dir_rename(zc->zc_name, zc->zc_value));
 	}
 }
 
@@ -4045,6 +4033,12 @@ zfs_ioc_recv(zfs_cmd_t *zc)
 		error = 1;
 	}
 #endif
+
+#ifdef _KERNEL
+	if (error == 0)
+		zvol_create_minors(tofs);
+#endif
+
 	/*
 	 * On error, restore the original props.
 	 */
@@ -5391,12 +5385,8 @@ zfs_ioctl_init(void)
 	    POOL_CHECK_SUSPENDED | POOL_CHECK_READONLY);
 
 	/*
- 	 * ZoL functions
+	 * ZoL functions
 	 */
-	zfs_ioctl_register_legacy(ZFS_IOC_CREATE_MINOR, zfs_ioc_create_minor,
-	    zfs_secpolicy_config, DATASET_NAME, B_FALSE, POOL_CHECK_NONE);
-	zfs_ioctl_register_legacy(ZFS_IOC_REMOVE_MINOR, zfs_ioc_remove_minor,
-	    zfs_secpolicy_config, DATASET_NAME, B_FALSE, POOL_CHECK_NONE);
 	zfs_ioctl_register_legacy(ZFS_IOC_EVENTS_NEXT, zfs_ioc_events_next,
 	    zfs_secpolicy_config, NO_NAME, B_FALSE, POOL_CHECK_NONE);
 	zfs_ioctl_register_legacy(ZFS_IOC_EVENTS_CLEAR, zfs_ioc_events_clear,
diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 79c56cd78..cb3d18108 100644
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -347,7 +347,7 @@ zvol_set_volsize(const char *name, uint64_t volsize)
 		goto out_doi;
 	}
 
-	if (get_disk_ro(zv->zv_disk) || (zv->zv_flags & ZVOL_RDONLY)) {
+	if (zv->zv_flags & ZVOL_RDONLY) {
 		error = SET_ERROR(EROFS);
 		goto out_doi;
 	}
@@ -396,7 +396,7 @@ zvol_set_volblocksize(const char *name, uint64_t volblocksize)
 		goto out;
 	}
 
-	if (get_disk_ro(zv->zv_disk) || (zv->zv_flags & ZVOL_RDONLY)) {
+	if (zv->zv_flags & ZVOL_RDONLY) {
 		error = SET_ERROR(EROFS);
 		goto out;
 	}
@@ -770,8 +770,7 @@ zvol_request(struct request_queue *q)
 			zvol_dispatch(zvol_read, req);
 			break;
 		case WRITE:
-			if (unlikely(get_disk_ro(zv->zv_disk)) ||
-			    unlikely(zv->zv_flags & ZVOL_RDONLY)) {
+			if (unlikely(zv->zv_flags & ZVOL_RDONLY)) {
 				__blk_end_request(req, -EROFS, size);
 				break;
 			}
@@ -1019,8 +1018,7 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 			goto out_mutex;
 	}
 
-	if ((flag & FMODE_WRITE) &&
-	    (get_disk_ro(zv->zv_disk) || (zv->zv_flags & ZVOL_RDONLY))) {
+	if ((flag & FMODE_WRITE) && (zv->zv_flags & ZVOL_RDONLY)) {
 		error = -EROFS;
 		goto out_open_count;
 	}
@@ -1235,7 +1233,7 @@ zvol_alloc(dev_t dev, const char *name)
 	zvol_state_t *zv;
 	int error = 0;
 
-	zv = kmem_zalloc(sizeof (zvol_state_t), KM_SLEEP);
+	zv = kmem_zalloc(sizeof (zvol_state_t), KM_PUSHPAGE);
 
 	spin_lock_init(&zv->zv_lock);
 	list_link_init(&zv->zv_next);
@@ -1315,7 +1313,7 @@ __zvol_snapdev_hidden(const char *name)
         char *atp;
         int error = 0;
 
-        parent = kmem_alloc(MAXPATHLEN, KM_SLEEP);
+        parent = kmem_alloc(MAXPATHLEN, KM_PUSHPAGE);
         (void) strlcpy(parent, name, MAXPATHLEN);
 
         if ((atp = strrchr(parent, '@')) != NULL) {
@@ -1352,7 +1350,7 @@ __zvol_create_minor(const char *name, boolean_t ignore_snapdev)
 			goto out;
 	}
 
-	doi = kmem_alloc(sizeof(dmu_object_info_t), KM_SLEEP);
+	doi = kmem_alloc(sizeof(dmu_object_info_t), KM_PUSHPAGE);
 
 	error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, zvol_tag, &os);
 	if (error)
@@ -1474,77 +1472,118 @@ zvol_remove_minor(const char *name)
 	return (error);
 }
 
+/*
+ * Rename a block device minor mode for the specified volume.
+ */
+static void
+__zvol_rename_minor(zvol_state_t *zv, const char *newname)
+{
+	int readonly = get_disk_ro(zv->zv_disk);
+
+	ASSERT(MUTEX_HELD(&zvol_state_lock));
+
+	strlcpy(zv->zv_name, newname, sizeof (zv->zv_name));
+
+	/*
+	 * The block device's read-only state is briefly changed causing
+	 * a KOBJ_CHANGE uevent to be issued.  This ensures udev detects
+	 * the name change and fixes the symlinks.  This does not change
+	 * ZVOL_RDONLY in zv->zv_flags so the actual read-only state never
+	 * changes.  This would normally be done using kobject_uevent() but
+	 * that is a GPL-only symbol which is why we need this workaround.
+	 */
+	set_disk_ro(zv->zv_disk, !readonly);
+	set_disk_ro(zv->zv_disk, readonly);
+}
+
 static int
 zvol_create_minors_cb(const char *dsname, void *arg)
 {
-	if (strchr(dsname, '/') == NULL)
-		return 0;
+	(void) zvol_create_minor(dsname);
 
-	(void) __zvol_create_minor(dsname, B_FALSE);
 	return (0);
 }
 
 /*
- * Create minors for specified pool, if pool is NULL create minors
- * for all available pools.
+ * Create minors for specified dataset including children and snapshots.
  */
 int
-zvol_create_minors(char *pool)
+zvol_create_minors(const char *name)
 {
-	spa_t *spa = NULL;
 	int error = 0;
 
+	if (!zvol_inhibit_dev)
+		error = dmu_objset_find((char *)name, zvol_create_minors_cb,
+		    NULL, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
+
+	return (SET_ERROR(error));
+}
+
+/*
+ * Remove minors for specified dataset including children and snapshots.
+ */
+void
+zvol_remove_minors(const char *name)
+{
+	zvol_state_t *zv, *zv_next;
+	int namelen = ((name) ? strlen(name) : 0);
+
 	if (zvol_inhibit_dev)
-		return (0);
+		return;
 
 	mutex_enter(&zvol_state_lock);
-	if (pool) {
-		error = dmu_objset_find(pool, zvol_create_minors_cb,
-		    NULL, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
-	} else {
-		mutex_enter(&spa_namespace_lock);
-		while ((spa = spa_next(spa)) != NULL) {
-			error = dmu_objset_find(spa_name(spa), zvol_create_minors_cb, NULL,
-			    DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
-			if (error)
-				break;
+
+	for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) {
+		zv_next = list_next(&zvol_state_list, zv);
+
+		if (name == NULL || strcmp(zv->zv_name, name) == 0 ||
+		    (strncmp(zv->zv_name, name, namelen) == 0 &&
+		    zv->zv_name[namelen] == '/')) {
+			zvol_remove(zv);
+			zvol_free(zv);
 		}
-		mutex_exit(&spa_namespace_lock);
 	}
-	mutex_exit(&zvol_state_lock);
 
-	return error;
+	mutex_exit(&zvol_state_lock);
 }
 
 /*
- * Remove minors for specified pool, if pool is NULL remove all minors.
+ * Rename minors for specified dataset including children and snapshots.
  */
 void
-zvol_remove_minors(const char *pool)
+zvol_rename_minors(const char *oldname, const char *newname)
 {
 	zvol_state_t *zv, *zv_next;
-	char *str;
+	int oldnamelen, newnamelen;
+	char *name;
 
 	if (zvol_inhibit_dev)
 		return;
 
-	str = kmem_zalloc(MAXNAMELEN, KM_SLEEP);
-	if (pool) {
-		(void) strncpy(str, pool, strlen(pool));
-		(void) strcat(str, "/");
-	}
+	oldnamelen = strlen(oldname);
+	newnamelen = strlen(newname);
+	name = kmem_alloc(MAXNAMELEN, KM_PUSHPAGE);
 
 	mutex_enter(&zvol_state_lock);
+
 	for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) {
 		zv_next = list_next(&zvol_state_list, zv);
 
-		if (pool == NULL || !strncmp(str, zv->zv_name, strlen(str))) {
-			zvol_remove(zv);
-			zvol_free(zv);
+		if (strcmp(zv->zv_name, oldname) == 0) {
+			__zvol_rename_minor(zv, newname);
+		} else if (strncmp(zv->zv_name, oldname, oldnamelen) == 0 &&
+		    (zv->zv_name[oldnamelen] == '/' ||
+		    zv->zv_name[oldnamelen] == '@')) {
+			snprintf(name, MAXNAMELEN, "%s%c%s", newname,
+			    zv->zv_name[oldnamelen],
+			    zv->zv_name + oldnamelen + 1);
+			__zvol_rename_minor(zv, name);
 		}
 	}
+
 	mutex_exit(&zvol_state_lock);
-	kmem_free(str, MAXNAMELEN);
+
+	kmem_free(name, MAXNAMELEN);
 }
 
 static int
@@ -1552,7 +1591,7 @@ snapdev_snapshot_changed_cb(const char *dsname, void *arg) {
 	uint64_t snapdev = *(uint64_t *) arg;
 
 	if (strchr(dsname, '@') == NULL)
-		return 0;
+		return (0);
 
 	switch (snapdev) {
 		case ZFS_SNAPDEV_VISIBLE:
@@ -1564,7 +1603,8 @@ snapdev_snapshot_changed_cb(const char *dsname, void *arg) {
 			(void) zvol_remove_minor(dsname);
 			break;
 	}
-	return 0;
+
+	return (0);
 }
 
 int
diff --git a/scripts/common.sh.in b/scripts/common.sh.in
index 29b85d3e1..3f63fc053 100644
--- a/scripts/common.sh.in
+++ b/scripts/common.sh.in
@@ -333,13 +333,14 @@ destroy_loop_devices() {
 }
 
 #
-# Create a device label.
+# Create a device label taking care to briefly wait if udev needs to settle.
 #
 label() {
 	local DEVICE=$1
 	local LABEL=$2
 
-	${PARTED} ${DEVICE} --script -- mklabel ${LABEL} || return 1
+	wait_udev ${DEVICE} 30 || return 1
+	${PARTED} ${DEVICE} --script -- mklabel ${LABEL} || return 2
 
 	return 0
 }