1 files changed, 55 insertions, 28 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index aa25fa335d3e..df43093b7a46 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -403,6 +403,7 @@ void btrfs_free_device(struct btrfs_device *device)
 static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
 {
 	struct btrfs_device *device;
+
 	WARN_ON(fs_devices->opened);
 	while (!list_empty(&fs_devices->devices)) {
 		device = list_entry(fs_devices->devices.next,
@@ -768,8 +769,11 @@ static noinline struct btrfs_device *device_list_add(const char *path,
 					BTRFS_SUPER_FLAG_CHANGING_FSID_V2);
 
 	error = lookup_bdev(path, &path_devt);
-	if (error)
+	if (error) {
+		btrfs_err(NULL, "failed to lookup block device for path %s: %d",
+			  path, error);
 		return ERR_PTR(error);
+	}
 
 	if (fsid_change_in_progress) {
 		if (!has_metadata_uuid)
@@ -836,6 +840,9 @@ static noinline struct btrfs_device *device_list_add(const char *path,
 		unsigned int nofs_flag;
 
 		if (fs_devices->opened) {
+			btrfs_err(NULL,
+		"device %s belongs to fsid %pU, and the fs is already mounted",
+				  path, fs_devices->fsid);
 			mutex_unlock(&fs_devices->device_list_mutex);
 			return ERR_PTR(-EBUSY);
 		}
@@ -905,6 +912,9 @@ static noinline struct btrfs_device *device_list_add(const char *path,
 			 * generation are equal.
 			 */
 			mutex_unlock(&fs_devices->device_list_mutex);
+			btrfs_err(NULL,
+"device %s already registered with a higher generation, found %llu expect %llu",
+				  path, found_transid, device->generation);
 			return ERR_PTR(-EEXIST);
 		}
 
@@ -1172,9 +1182,22 @@ void btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 
 	mutex_lock(&uuid_mutex);
 	close_fs_devices(fs_devices);
-	if (!fs_devices->opened)
+	if (!fs_devices->opened) {
 		list_splice_init(&fs_devices->seed_list, &list);
 
+		/*
+		 * If the struct btrfs_fs_devices is not assembled with any
+		 * other device, it can be re-initialized during the next mount
+		 * without the needing device-scan step. Therefore, it can be
+		 * fully freed.
+		 */
+		if (fs_devices->num_devices == 1) {
+			list_del(&fs_devices->fs_list);
+			free_fs_devices(fs_devices);
+		}
+	}
+
+
 	list_for_each_entry_safe(fs_devices, tmp, &list, seed_list) {
 		close_fs_devices(fs_devices);
 		list_del(&fs_devices->seed_list);
@@ -1591,7 +1614,7 @@ again:
 	if (ret < 0)
 		goto out;
 
-	while (1) {
+	while (search_start < search_end) {
 		l = path->nodes[0];
 		slot = path->slots[0];
 		if (slot >= btrfs_header_nritems(l)) {
@@ -1614,6 +1637,9 @@ again:
 		if (key.type != BTRFS_DEV_EXTENT_KEY)
 			goto next;
 
+		if (key.offset > search_end)
+			break;
+
 		if (key.offset > search_start) {
 			hole_size = key.offset - search_start;
 			dev_extent_hole_check(device, &search_start, &hole_size,
@@ -1674,6 +1700,7 @@ next:
 	else
 		ret = 0;
 
+	ASSERT(max_hole_start + max_hole_size <= search_end);
 out:
 	btrfs_free_path(path);
 	*start = max_hole_start;
@@ -2005,42 +2032,42 @@ static u64 btrfs_num_devices(struct btrfs_fs_info *fs_info)
 	return num_devices;
 }
 
+static void btrfs_scratch_superblock(struct btrfs_fs_info *fs_info,
+				     struct block_device *bdev, int copy_num)
+{
+	struct btrfs_super_block *disk_super;
+	const size_t len = sizeof(disk_super->magic);
+	const u64 bytenr = btrfs_sb_offset(copy_num);
+	int ret;
+
+	disk_super = btrfs_read_disk_super(bdev, bytenr, bytenr);
+	if (IS_ERR(disk_super))
+		return;
+
+	memset(&disk_super->magic, 0, len);
+	folio_mark_dirty(virt_to_folio(disk_super));
+	btrfs_release_disk_super(disk_super);
+
+	ret = sync_blockdev_range(bdev, bytenr, bytenr + len - 1);
+	if (ret)
+		btrfs_warn(fs_info, "error clearing superblock number %d (%d)",
+			copy_num, ret);
+}
+
 void btrfs_scratch_superblocks(struct btrfs_fs_info *fs_info,
 			       struct block_device *bdev,
 			       const char *device_path)
 {
-	struct btrfs_super_block *disk_super;
 	int copy_num;
 
 	if (!bdev)
 		return;
 
 	for (copy_num = 0; copy_num < BTRFS_SUPER_MIRROR_MAX; copy_num++) {
-		struct page *page;
-		int ret;
-
-		disk_super = btrfs_read_dev_one_super(bdev, copy_num, false);
-		if (IS_ERR(disk_super))
-			continue;
-
-		if (bdev_is_zoned(bdev)) {
+		if (bdev_is_zoned(bdev))
 			btrfs_reset_sb_log_zones(bdev, copy_num);
-			continue;
-		}
-
-		memset(&disk_super->magic, 0, sizeof(disk_super->magic));
-
-		page = virt_to_page(disk_super);
-		set_page_dirty(page);
-		lock_page(page);
-		/* write_on_page() unlocks the page */
-		ret = write_one_page(page);
-		if (ret)
-			btrfs_warn(fs_info,
-				"error clearing superblock number %d (%d)",
-				copy_num, ret);
-		btrfs_release_disk_super(disk_super);
-
+		else
+			btrfs_scratch_superblock(fs_info, bdev, copy_num);
 	}
 
 	/* Notify udev that device has changed */