1 files changed, 69 insertions, 16 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a2d07fa3cfdf..f15591f3e54f 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -692,6 +692,16 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
 	device->bdev = file_bdev(bdev_file);
 	clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 
+	if (device->devt != device->bdev->bd_dev) {
+		btrfs_warn(NULL,
+			   "device %s maj:min changed from %d:%d to %d:%d",
+			   device->name->str, MAJOR(device->devt),
+			   MINOR(device->devt), MAJOR(device->bdev->bd_dev),
+			   MINOR(device->bdev->bd_dev));
+
+		device->devt = device->bdev->bd_dev;
+	}
+
 	fs_devices->open_devices++;
 	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
 	    device->devid != BTRFS_DEV_REPLACE_DEVID) {
@@ -1174,23 +1184,30 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
 	struct btrfs_device *device;
 	struct btrfs_device *latest_dev = NULL;
 	struct btrfs_device *tmp_device;
+	int ret = 0;
 
 	list_for_each_entry_safe(device, tmp_device, &fs_devices->devices,
 				 dev_list) {
-		int ret;
+		int ret2;
 
-		ret = btrfs_open_one_device(fs_devices, device, flags, holder);
-		if (ret == 0 &&
+		ret2 = btrfs_open_one_device(fs_devices, device, flags, holder);
+		if (ret2 == 0 &&
 		    (!latest_dev || device->generation > latest_dev->generation)) {
 			latest_dev = device;
-		} else if (ret == -ENODATA) {
+		} else if (ret2 == -ENODATA) {
 			fs_devices->num_devices--;
 			list_del(&device->dev_list);
 			btrfs_free_device(device);
 		}
+		if (ret == 0 && ret2 != 0)
+			ret = ret2;
 	}
-	if (fs_devices->open_devices == 0)
+
+	if (fs_devices->open_devices == 0) {
+		if (ret)
+			return ret;
 		return -EINVAL;
+	}
 
 	fs_devices->opened = 1;
 	fs_devices->latest_dev = latest_dev;
@@ -1303,6 +1320,47 @@ int btrfs_forget_devices(dev_t devt)
 	return ret;
 }
 
+static bool btrfs_skip_registration(struct btrfs_super_block *disk_super,
+				    const char *path, dev_t devt,
+				    bool mount_arg_dev)
+{
+	struct btrfs_fs_devices *fs_devices;
+
+	/*
+	 * Do not skip device registration for mounted devices with matching
+	 * maj:min but different paths. Booting without initrd relies on
+	 * /dev/root initially, later replaced with the actual root device.
+	 * A successful scan ensures grub2-probe selects the correct device.
+	 */
+	list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
+		struct btrfs_device *device;
+
+		mutex_lock(&fs_devices->device_list_mutex);
+
+		if (!fs_devices->opened) {
+			mutex_unlock(&fs_devices->device_list_mutex);
+			continue;
+		}
+
+		list_for_each_entry(device, &fs_devices->devices, dev_list) {
+			if (device->bdev && (device->bdev->bd_dev == devt) &&
+			    strcmp(device->name->str, path) != 0) {
+				mutex_unlock(&fs_devices->device_list_mutex);
+
+				/* Do not skip registration. */
+				return false;
+			}
+		}
+		mutex_unlock(&fs_devices->device_list_mutex);
+	}
+
+	if (!mount_arg_dev && btrfs_super_num_devices(disk_super) == 1 &&
+	    !(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING))
+		return true;
+
+	return false;
+}
+
 /*
  * Look for a btrfs signature on a device. This may be called out of the mount path
  * and we are not allowed to call set_blocksize during the scan. The superblock
@@ -1320,6 +1378,7 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags,
 	struct btrfs_device *device = NULL;
 	struct file *bdev_file;
 	u64 bytenr, bytenr_orig;
+	dev_t devt;
 	int ret;
 
 	lockdep_assert_held(&uuid_mutex);
@@ -1359,19 +1418,13 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags,
 		goto error_bdev_put;
 	}
 
-	if (!mount_arg_dev && btrfs_super_num_devices(disk_super) == 1 &&
-	    !(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING)) {
-		dev_t devt;
+	devt = file_bdev(bdev_file)->bd_dev;
+	if (btrfs_skip_registration(disk_super, path, devt, mount_arg_dev)) {
+		pr_debug("BTRFS: skip registering single non-seed device %s (%d:%d)\n",
+			  path, MAJOR(devt), MINOR(devt));
 
-		ret = lookup_bdev(path, &devt);
-		if (ret)
-			btrfs_warn(NULL, "lookup bdev failed for path %s: %d",
-				   path, ret);
-		else
-			btrfs_free_stale_devices(devt, NULL);
+		btrfs_free_stale_devices(devt, NULL);
 
-	pr_debug("BTRFS: skip registering single non-seed device %s (%d:%d)\n",
-			path, MAJOR(devt), MINOR(devt));
 		device = NULL;
 		goto free_disk_super;
 	}