Btrfs-progs: add a btrfs-select-super command to overwrite the super

Btrfs stores multiple copies of the superblock, and for common power-failure
crashes where barriers were not in use, one of the super copies is often
valid while the first copy is not.

This adds a btrfs-select-super -s N /dev/xxx command, which can
overwrite all the super blocks with a copy that you have already
determined is valid with btrfsck -s

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/disk-io.h b/disk-io.h
index 49e5692..7ebec24 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -47,6 +47,7 @@ struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes);
 struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
 				 int writes);
 int close_ctree(struct btrfs_root *root);
+int write_all_supers(struct btrfs_root *root);
 int write_ctree_super(struct btrfs_trans_handle *trans,
 		      struct btrfs_root *root);
 int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr);