4 files changed, 166 insertions, 46 deletions

diff --git a/cmd/zpool/zpool_vdev.c b/cmd/zpool/zpool_vdev.c
index 8bbbf6615695..cf87554d5d8b 100644
--- a/cmd/zpool/zpool_vdev.c
+++ b/cmd/zpool/zpool_vdev.c
@@ -1198,12 +1198,10 @@ make_disks(zpool_handle_t *zhp, nvlist_t *nv)
 
 		/*
 		 * Remove any previously existing symlink from a udev path to
-		 * the device before labeling the disk.  This makes
-		 * zpool_label_disk_wait() truly wait for the new link to show
-		 * up instead of returning if it finds an old link still in
-		 * place.  Otherwise there is a window between when udev
-		 * deletes and recreates the link during which access attempts
-		 * will fail with ENOENT.
+		 * the device before labeling the disk.  This ensures that
+		 * only newly created links are used.  Otherwise there is a
+		 * window between when udev deletes and recreates the link
+		 * during which access attempts will fail with ENOENT.
 		 */
 		strncpy(udevpath, path, MAXPATHLEN);
 		(void) zfs_append_partition(udevpath, MAXPATHLEN);
@@ -1227,6 +1225,8 @@ make_disks(zpool_handle_t *zhp, nvlist_t *nv)
 		 * and then block until udev creates the new link.
 		 */
 		if (!is_exclusive || !is_spare(NULL, udevpath)) {
+			char *devnode = strrchr(devpath, '/') + 1;
+
 			ret = strncmp(udevpath, UDISK_ROOT, strlen(UDISK_ROOT));
 			if (ret == 0) {
 				ret = lstat64(udevpath, &statbuf);
@@ -1234,18 +1234,29 @@ make_disks(zpool_handle_t *zhp, nvlist_t *nv)
 					(void) unlink(udevpath);
 			}
 
-			if (zpool_label_disk(g_zfs, zhp,
-			    strrchr(devpath, '/') + 1) == -1)
+			/*
+			 * When labeling a pool the raw device node name
+			 * is provided as it appears under /dev/.
+			 */
+			if (zpool_label_disk(g_zfs, zhp, devnode) == -1)
 				return (-1);
 
+			/*
+			 * Wait for udev to signal the device is available
+			 * by the provided path.
+			 */
 			ret = zpool_label_disk_wait(udevpath, DISK_LABEL_WAIT);
 			if (ret) {
-				(void) fprintf(stderr, gettext("cannot "
-				    "resolve path '%s': %d\n"), udevpath, ret);
-				return (-1);
+				(void) fprintf(stderr,
+				    gettext("missing link: %s was "
+				    "partitioned but %s is missing\n"),
+				    devnode, udevpath);
+				return (ret);
 			}
 
-			(void) zero_label(udevpath);
+			ret = zero_label(udevpath);
+			if (ret)
+				return (ret);
 		}
 
 		/*
@@ -1259,8 +1270,7 @@ make_disks(zpool_handle_t *zhp, nvlist_t *nv)
 		/*
 		 * Update device id strings for whole disks (Linux only)
 		 */
-		if (wholedisk)
-			update_vdev_config_dev_strs(nv);
+		update_vdev_config_dev_strs(nv);
 
 		return (0);
 	}
diff --git a/lib/libzfs/libzfs_import.c b/lib/libzfs/libzfs_import.c
index 8f27ed58c8df..2776ed29cd00 100644
--- a/lib/libzfs/libzfs_import.c
+++ b/lib/libzfs/libzfs_import.c
@@ -260,6 +260,86 @@ udev_device_is_ready(struct udev_device *dev)
 }
 
 /*
+ * Wait up to timeout_ms for udev to set up the device node.  The device is
+ * considered ready when libudev determines it has been initialized, all of
+ * the device links have been verified to exist, and it has been allowed to
+ * settle.  At this point the device the device can be accessed reliably.
+ * Depending on the complexity of the udev rules this process could take
+ * several seconds.
+ */
+int
+zpool_label_disk_wait(char *path, int timeout_ms)
+{
+	struct udev *udev;
+	struct udev_device *dev = NULL;
+	char nodepath[MAXPATHLEN];
+	char *sysname = NULL;
+	int ret = ENODEV;
+	int settle_ms = 50;
+	long sleep_ms = 10;
+	hrtime_t start, settle;
+
+	if ((udev = udev_new()) == NULL)
+		return (ENXIO);
+
+	start = gethrtime();
+	settle = 0;
+
+	do {
+		if (sysname == NULL) {
+			if (realpath(path, nodepath) != NULL) {
+				sysname = strrchr(nodepath, '/') + 1;
+			} else {
+				(void) usleep(sleep_ms * MILLISEC);
+				continue;
+			}
+		}
+
+		dev = udev_device_new_from_subsystem_sysname(udev,
+		    "block", sysname);
+		if ((dev != NULL) && udev_device_is_ready(dev)) {
+			struct udev_list_entry *links, *link;
+
+			ret = 0;
+			links = udev_device_get_devlinks_list_entry(dev);
+
+			udev_list_entry_foreach(link, links) {
+				struct stat64 statbuf;
+				const char *name;
+
+				name = udev_list_entry_get_name(link);
+				errno = 0;
+				if (stat64(name, &statbuf) == 0 && errno == 0)
+					continue;
+
+				settle = 0;
+				ret = ENODEV;
+				break;
+			}
+
+			if (ret == 0) {
+				if (settle == 0) {
+					settle = gethrtime();
+				} else if (NSEC2MSEC(gethrtime() - settle) >=
+				    settle_ms) {
+					udev_device_unref(dev);
+					break;
+				}
+			}
+		}
+
+		udev_device_unref(dev);
+		(void) usleep(sleep_ms * MILLISEC);
+
+	} while (NSEC2MSEC(gethrtime() - start) < timeout_ms);
+
+	udev_unref(udev);
+
+	return (ret);
+}
+
+
+/*
  * Encode the persistent devices strings
  * used for the vdev disk label
  */
@@ -414,6 +494,41 @@ is_mpath_whole_disk(const char *path)
 	return (B_FALSE);
 }
 
+/*
+ * Wait up to timeout_ms for udev to set up the device node.  The device is
+ * considered ready when the provided path have been verified to exist and
+ * it has been allowed to settle.  At this point the device the device can
+ * be accessed reliably.  Depending on the complexity of the udev rules thisi
+ * process could take several seconds.
+ */
+int
+zpool_label_disk_wait(char *path, int timeout_ms)
+{
+	int settle_ms = 50;
+	long sleep_ms = 10;
+	hrtime_t start, settle;
+	struct stat64 statbuf;
+
+	start = gethrtime();
+	settle = 0;
+
+	do {
+		errno = 0;
+		if ((stat64(path, &statbuf) == 0) && (errno == 0)) {
+			if (settle == 0)
+				settle = gethrtime();
+			else if (NSEC2MSEC(gethrtime() - settle) >= settle_ms)
+				return (0);
+		} else if (errno != ENOENT) {
+			return (errno);
+		}
+
+		usleep(sleep_ms * MILLISEC);
+	} while (NSEC2MSEC(gethrtime() - start) < timeout_ms);
+
+	return (ENODEV);
+}
+
 void
 update_vdev_config_dev_strs(nvlist_t *nv)
 {
diff --git a/lib/libzfs/libzfs_pool.c b/lib/libzfs/libzfs_pool.c
index 214c57ab4b46..c405abe3edf1 100644
--- a/lib/libzfs/libzfs_pool.c
+++ b/lib/libzfs/libzfs_pool.c
@@ -4122,30 +4122,7 @@ find_start_block(nvlist_t *config)
 	return (MAXOFFSET_T);
 }
 
-int
-zpool_label_disk_wait(char *path, int timeout)
-{
-	struct stat64 statbuf;
-	int i;
-
-	/*
-	 * Wait timeout miliseconds for a newly created device to be available
-	 * from the given path.  There is a small window when a /dev/ device
-	 * will exist and the udev link will not, so we must wait for the
-	 * symlink.  Depending on the udev rules this may take a few seconds.
-	 */
-	for (i = 0; i < timeout; i++) {
-		usleep(1000);
-
-		errno = 0;
-		if ((stat64(path, &statbuf) == 0) && (errno == 0))
-			return (0);
-	}
-
-	return (ENOENT);
-}
-
-int
+static int
 zpool_label_disk_check(char *path)
 {
 	struct dk_gpt *vtoc;
@@ -4310,12 +4287,11 @@ zpool_label_disk(libzfs_handle_t *hdl, zpool_handle_t *zhp, char *name)
 	(void) close(fd);
 	efi_free(vtoc);
 
-	/* Wait for the first expected partition to appear. */
-
 	(void) snprintf(path, sizeof (path), "%s/%s", DISK_ROOT, name);
 	(void) zfs_append_partition(path, MAXPATHLEN);
 
-	rval = zpool_label_disk_wait(path, 3000);
+	/* Wait to udev to signal use the device has settled. */
+	rval = zpool_label_disk_wait(path, DISK_LABEL_WAIT);
 	if (rval) {
 		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "failed to "
 		    "detect device partitions on '%s': %d"), path, rval);
diff --git a/module/zfs/vdev_disk.c b/module/zfs/vdev_disk.c
index cdb8f78e2788..9b51ecc1d968 100644
--- a/module/zfs/vdev_disk.c
+++ b/module/zfs/vdev_disk.c
@@ -244,12 +244,12 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 {
 	struct block_device *bdev = ERR_PTR(-ENXIO);
 	vdev_disk_t *vd;
-	int mode, block_size;
+	int count = 0, mode, block_size;
 
 	/* Must have a pathname and it must be absolute. */
 	if (v->vdev_path == NULL || v->vdev_path[0] != '/') {
 		v->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
-		return (EINVAL);
+		return (SET_ERROR(EINVAL));
 	}
 
 	/*
@@ -264,7 +264,7 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 
 	vd = kmem_zalloc(sizeof (vdev_disk_t), KM_SLEEP);
 	if (vd == NULL)
-		return (ENOMEM);
+		return (SET_ERROR(ENOMEM));
 
 	/*
 	 * Devices are always opened by the path provided at configuration
@@ -279,16 +279,35 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 	 * /dev/[hd]d devices which may be reordered due to probing order.
 	 * Devices in the wrong locations will be detected by the higher
 	 * level vdev validation.
+	 *
+	 * The specified paths may be briefly removed and recreated in
+	 * response to udev events.  This should be exceptionally unlikely
+	 * because the zpool command makes every effort to verify these paths
+	 * have already settled prior to reaching this point.  Therefore,
+	 * a ENOENT failure at this point is highly likely to be transient
+	 * and it is reasonable to sleep and retry before giving up.  In
+	 * practice delays have been observed to be on the order of 100ms.
 	 */
 	mode = spa_mode(v->vdev_spa);
 	if (v->vdev_wholedisk && v->vdev_expanding)
 		bdev = vdev_disk_rrpart(v->vdev_path, mode, vd);
-	if (IS_ERR(bdev))
+
+	while (IS_ERR(bdev) && count < 50) {
 		bdev = vdev_bdev_open(v->vdev_path,
 		    vdev_bdev_mode(mode), zfs_vdev_holder);
+		if (unlikely(PTR_ERR(bdev) == -ENOENT)) {
+			msleep(10);
+			count++;
+		} else if (IS_ERR(bdev)) {
+			break;
+		}
+	}
+
 	if (IS_ERR(bdev)) {
+		dprintf("failed open v->vdev_path=%s, error=%d count=%d\n",
+		    v->vdev_path, -PTR_ERR(bdev), count);
 		kmem_free(vd, sizeof (vdev_disk_t));
-		return (-PTR_ERR(bdev));
+		return (SET_ERROR(-PTR_ERR(bdev)));
 	}
 
 	v->vdev_tsd = vd;