Others might be thinking this to so I better ask:
Does this just read the first copy in the case of dup, raid1, etc. and plow on?
I'm
not sure how you would handle a mismatch due to a hardware error.
Perhaps read all the copies and create another subvolume containing the
mismatched copies?
Thanks,
Kyle
> From: jbacik@xxxxxx
> To: linux-btrfs@xxxxxxxxxxxxxxx
> Subject: [PATCH] Btrfs-progs: rebuild the crc tree with --init-csum-tree
> Date: Wed, 1 Oct 2014 10:34:51 -0400
>
> We have --init-csum-tree, which just empties the csum tree. I'm not sure why we
> would ever need this, but we definitely need to be able to rebuild the csum tree
> in some cases. This patch adds the ability to completely rebuild the crc tree
> by reading all of the data and adding csum entries for them. This patch doesn't
> pay attention to NODATASUM inodes, it'll happily add csums for everything.
> Thanks,
>
> Signed-off-by: Josef Bacik <jbacik@xxxxxx>
> ---
> cmds-check.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 98 insertions(+)
>
> diff --git a/cmds-check.c b/cmds-check.c
> index 03b0fbd..3141aa4 100644
> --- a/cmds-check.c
> +++ b/cmds-check.c
> @@ -6625,6 +6625,98 @@ out:
> return ret;
> }
>
> +static int populate_csum(struct btrfs_trans_handle *trans,
> + struct btrfs_root *csum_root, char *buf, u64 start,
> + u64 len)
> +{
> + u64 offset = 0;
> + u64 sectorsize;
> + int ret = 0;
> +
> + while (offset < len) {
> + sectorsize = csum_root->sectorsize;
> + ret = read_extent_data(csum_root, buf, start + offset,
> + §orsize, 0);
> + if (ret)
> + break;
> + ret = btrfs_csum_file_block(trans, csum_root, start + len,
> + start + offset, buf, sectorsize);
> + if (ret)
> + break;
> + offset += sectorsize;
> + }
> + return ret;
> +}
> +
> +static int fill_csum_tree(struct btrfs_trans_handle *trans,
> + struct btrfs_root *csum_root)
> +{
> + struct btrfs_root *extent_root = csum_root->fs_info->extent_root;
> + struct btrfs_path *path;
> + struct btrfs_extent_item *ei;
> + struct extent_buffer *leaf;
> + char *buf;
> + struct btrfs_key key;
> + int ret;
> +
> + path = btrfs_alloc_path();
> + if (!path)
> + return -ENOMEM;
> +
> + key.objectid = 0;
> + key.type = BTRFS_EXTENT_ITEM_KEY;
> + key.offset = 0;
> +
> + ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
> + if (ret < 0) {
> + btrfs_free_path(path);
> + return ret;
> + }
> +
> + buf = malloc(csum_root->sectorsize);
> + if (!buf) {
> + btrfs_free_path(path);
> + return -ENOMEM;
> + }
> +
> + while (1) {
> + if (path->slots[0]>= btrfs_header_nritems(path->nodes[0])) {
> + ret = btrfs_next_leaf(extent_root, path);
> + if (ret < 0)
> + break;
> + if (ret) {
> + ret = 0;
> + break;
> + }
> + }
> + leaf = path->nodes[0];
> +
> + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
> + if (key.type != BTRFS_EXTENT_ITEM_KEY) {
> + path->slots[0]++;
> + continue;
> + }
> +
> + ei = btrfs_item_ptr(leaf, path->slots[0],
> + struct btrfs_extent_item);
> + if (!(btrfs_extent_flags(leaf, ei) &
> + BTRFS_EXTENT_FLAG_DATA)) {
> + path->slots[0]++;
> + continue;
> + }
> +
> + ret = populate_csum(trans, csum_root, buf, key.objectid,
> + key.offset);
> + if (ret)
> + break;
> + path->slots[0]++;
> + }
> +
> + btrfs_free_path(path);
> + free(buf);
> + return ret;
> +}
> +
> static struct option long_options[] = {
> { "super", 1, NULL, 's' },
> { "repair", 0, NULL, 0 },
> @@ -6794,6 +6886,12 @@ int cmd_check(int argc, char **argv)
> ret = -EIO;
> goto close_out;
> }
> +
> + ret = fill_csum_tree(trans, info->csum_root);
> + if (ret) {
> + fprintf(stderr, "crc refilling failed\n");
> + return -EIO;
> + }
> }
> /*
> * Ok now we commit and run the normal fsck, which will add
> --
> 1.8.3.1
>
> --
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