[PATCH 10/26] Btrfs: add btrfs_scratch_superblock() function

[Stefan Behrens]

This new function is used by the device replace procedure in
a later patch.

Signed-off-by: Stefan Behrens <sbehr...@giantdisaster.de>
---
 fs/btrfs/volumes.c | 18 ++++++++++++++++++
 fs/btrfs/volumes.h |  1 +
 2 files changed, 19 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c79f8db..bf5e68b 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5111,3 +5111,21 @@ int btrfs_get_dev_stats(struct btrfs_root *root,
                stats->nr_items = BTRFS_DEV_STAT_VALUES_MAX;
        return 0;
 }
+
+int btrfs_scratch_superblock(struct btrfs_device *device)
+{
+       struct buffer_head *bh;
+       struct btrfs_super_block *disk_super;
+
+       bh = btrfs_read_dev_super(device->bdev);
+       if (!bh)
+               return -EINVAL;
+       disk_super = (struct btrfs_super_block *)bh->b_data;
+
+       memset(&disk_super->magic, 0, sizeof(disk_super->magic));
+       set_buffer_dirty(bh);
+       sync_dirty_buffer(bh);
+       brelse(bh);
+
+       return 0;
+}
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index ad5566d..7eaaf4e 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -301,6 +301,7 @@ int btrfs_get_dev_stats(struct btrfs_root *root,
 int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info);
 int btrfs_run_dev_stats(struct btrfs_trans_handle *trans,
                        struct btrfs_fs_info *fs_info);
+int btrfs_scratch_superblock(struct btrfs_device *device);
 
 static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
                                      int index)
-- 
1.8.0

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