On 2018年03月27日 15:06, Lu Fengqi wrote: > The function will find the root_item specified by the subvol_id, > clear the BTRFS_ROOT_SUBVOL_DEAD flag and set root_refs to one.
Sorry I didn't point it out in btrfs_link_subvol() patch, but at least
to me, refs should only be modified by btrfs_link_subvol(), just like
btrfs_unlink().
Thanks,
Qu
>
> Signed-off-by: Lu Fengqi <lufq.f...@cn.fujitsu.com>
> ---
> ctree.h | 1 +
> undelete-subvol.c | 55
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 56 insertions(+)
>
> diff --git a/ctree.h b/ctree.h
> index 4bff0b821472..7c0b8150bc4e 100644
> --- a/ctree.h
> +++ b/ctree.h
> @@ -184,6 +184,7 @@ static int btrfs_csum_sizes[] = { 4 };
> #define BTRFS_FT_MAX 9
>
> #define BTRFS_ROOT_SUBVOL_RDONLY (1ULL << 0)
> +#define BTRFS_ROOT_SUBVOL_DEAD (1ULL << 48)
>
> /*
> * the key defines the order in the tree, and so it also defines (optimal)
> diff --git a/undelete-subvol.c b/undelete-subvol.c
> index 00fcc4895778..781057df2b84 100644
> --- a/undelete-subvol.c
> +++ b/undelete-subvol.c
> @@ -12,6 +12,9 @@
> */
>
> #include "ctree.h"
> +#include "transaction.h"
> +#include "disk-io.h"
> +#include "messages.h"
>
> /*
> * Determines whether the subvolume is intact, according to the drop_progress
> @@ -51,3 +54,55 @@ out:
> btrfs_release_path(&path);
> return ret;
> }
> +
> +/*
> + * Clear BTRFS_ROOT_SUBVOL_DEAD flag and set the root_refs to one.
> + *
> + * @root the root of root tree.
> + * @subvol_id specify the root_item which will be modified.
> + *
> + * Return 0 if no error occurred.
> + */
> +static int recover_dead_root(struct btrfs_trans_handle *trans,
> + struct btrfs_root *root, u64 subvol_id)
> +{
> + struct btrfs_key key;
> + struct btrfs_path path;
> + struct extent_buffer *leaf;
> + struct btrfs_root_item root_item;
> + u64 root_flags;
> + u64 offset;
> + int ret;
> +
> + key.objectid = subvol_id;
> + key.type = BTRFS_ROOT_ITEM_KEY;
> + key.offset = 0;
> +
> + btrfs_init_path(&path);
> + ret = btrfs_search_slot(trans, root, &key, &path, 0, 0);
> + if (ret) {
> + error("couldn't find ROOT_ITEM for %llu failed: %d",
> + subvol_id, ret);
> + goto out;
> + }
> +
> + leaf = path.nodes[0];
> +
> + offset = btrfs_item_ptr_offset(leaf, path.slots[0]);
> + read_extent_buffer(leaf, &root_item, offset, sizeof(root_item));
> +
> + /* Clear BTRFS_ROOT_SUBVOL_DEAD */
> + root_flags = btrfs_root_flags(&root_item);
> + btrfs_set_root_flags(&root_item,
> + root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
> +
> + /* Increase the refs */
> + btrfs_set_root_refs(&root_item, 1);
> +
> + write_extent_buffer(leaf, &root_item, offset, sizeof(root_item));
> + btrfs_mark_buffer_dirty(leaf);
> +
> +out:
> + btrfs_release_path(&path);
> + return ret;
> +}
>
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