+/*
+ * Expanding a whole disk vdev involves invoking BLKRRPART on the
+ * whole disk device. This poses a problem, because BLKRRPART will
+ * return EBUSY if one of the disk's partitions is open. That's why
+ * we have to do it here, just before opening the data partition.
+ * Unfortunately, BLKRRPART works by dropping all partitions and
+ * recreating them, which means that for a short time window, all
+ * /dev/sdxN device files disappear (until udev recreates them).
+ * This means two things:
+ * - When we open the data partition just after a BLKRRPART, we
+ * can't do it using the normal device file path because of the
+ * obvious race condition with udev. Instead, we use reliable
+ * kernel APIs to get a handle to the new partition device from
+ * the whole disk device.
+ * - Because vdev_disk_open() initially needs to find the device
+ * using its path, multiple vdev_disk_open() invocations in
+ * short succession on the same disk with BLKRRPARTs in the
+ * middle have a high probability of failure (because of the
+ * race condition with udev). A typical situation where this
+ * might happen is when the zpool userspace tool does a
+ * TRYIMPORT immediately followed by an IMPORT. For this
+ * reason, we only invoke BLKRRPART in the module when strictly
+ * necessary (zpool online -e case), and rely on userspace to
+ * do it when possible.
+ */
+static struct block_device *
+vdev_disk_rrpart(const char *path, int mode, vdev_disk_t *vd)
+{
+#if defined(HAVE_3ARG_BLKDEV_GET) && defined(HAVE_GET_GENDISK)
+ struct block_device *bdev, *result = ERR_PTR(-ENXIO);
+ struct gendisk *disk;
+ int error, partno;
+
+ bdev = vdev_bdev_open(path, vdev_bdev_mode(mode), vd);
+ if (IS_ERR(bdev))
+ return bdev;
+
+ disk = get_gendisk(bdev->bd_dev, &partno);
+ vdev_bdev_close(bdev, vdev_bdev_mode(mode));
+
+ if (disk) {
+ bdev = bdget(disk_devt(disk));
+ if (bdev) {
+ error = blkdev_get(bdev, vdev_bdev_mode(mode), vd);
+ if (error == 0)
+ error = ioctl_by_bdev(bdev, BLKRRPART, 0);
+ vdev_bdev_close(bdev, vdev_bdev_mode(mode));
+ }
+
+ bdev = bdget_disk(disk, partno);
+ if (bdev) {
+ error = blkdev_get(bdev,
+ vdev_bdev_mode(mode) | FMODE_EXCL, vd);
+ if (error == 0)
+ result = bdev;
+ }
+ put_disk(disk);
+ }
+
+ return result;
+#else
+ return ERR_PTR(-EOPNOTSUPP);
+#endif /* defined(HAVE_3ARG_BLKDEV_GET) && defined(HAVE_GET_GENDISK) */
+}
+
git://git.camperquake.de / zfs.git / commitdiff