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btrfs-progs: image: Remove all existing dev extents for later rebuild 

For multi-disk btrfs image recovered to single disk, the dev tree would
look like:

        item 2 key (1 DEV_EXTENT 22020096)
                dev extent chunk_tree 3
                chunk_objectid 256 chunk_offset 22020096 length 8388608
        item 3 key (1 DEV_EXTENT 30408704)
                dev extent chunk_tree 3
                chunk_objectid 256 chunk_offset 30408704 length 1073741824
        item 4 key (1 DEV_EXTENT 1104150528)
                dev extent chunk_tree 3
                chunk_objectid 256 chunk_offset 1104150528 length 536870912
        item 5 key (2 DEV_EXTENT 1048576)
                dev extent chunk_tree 3
                chunk_objectid 256 chunk_offset 22020096 length 8388608
        item 6 key (2 DEV_EXTENT 9437184)
                dev extent chunk_tree 3
                chunk_objectid 256 chunk_offset 30408704 length 1073741824
        item 7 key (2 DEV_EXTENT 1083179008)
                dev extent chunk_tree 3
                chunk_objectid 256 chunk_offset 1104150528 length 536870912

However in chunk tree, we only use devid 2, thus devid 1 is completely
garbage:

        item 0 key (DEV_ITEMS DEV_ITEM 2)
        item 1 key (FIRST_CHUNK_TREE CHUNK_ITEM 22020096) itemoff 16105 itemsize 80
                length 8388608 owner 2 stripe_len 65536 type SYSTEM
                num_stripes 1 sub_stripes 0
                        stripe 0 devid 2 offset 1048576
        item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 30408704) itemoff 16025 itemsize 80
                length 1073741824 owner 2 stripe_len 65536 type METADATA
                num_stripes 1 sub_stripes 0
                        stripe 0 devid 2 offset 9437184
        item 3 key (FIRST_CHUNK_TREE CHUNK_ITEM 1104150528) itemoff 15945 itemsize 80
                length 1073741824 owner 2 stripe_len 65536 type DATA
                num_stripes 1 sub_stripes 0
                        stripe 0 devid 2 offset 1083179008

To fix the problem, the most straight-forward way is to remove all
existing dev extents, and then re-fill correct dev extents from chunk.

So this patch just follows the straight-forward way to fix it, causing
the final dev extents layout to match chunk tree, and make btrfs check
happy.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Qu Wenruo 2018-11-27 16:38:27 +08:00 committed by David Sterba
parent e6c1fa297a
commit a1a98ee7a8
1 changed files with 105 additions and 0 deletions
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105
image/main.c
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@ -2209,6 +2209,107 @@ static void fixup_block_groups(struct btrfs_fs_info *fs_info)
}
}
static int remove_all_dev_extents(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *root = fs_info->dev_root;
struct btrfs_path path;
struct btrfs_key key;
struct extent_buffer *leaf;
int slot;
int ret;
key.objectid = 1;
key.type = BTRFS_DEV_EXTENT_KEY;
key.offset = 0;
btrfs_init_path(&path);
ret = btrfs_search_slot(trans, root, &key, &path, -1, 1);
if (ret < 0) {
errno = -ret;
error("failed to search dev tree: %m");
return ret;
}
while (1) {
slot = path.slots[0];
leaf = path.nodes[0];
if (slot >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(root, &path);
if (ret < 0) {
errno = -ret;
error("failed to search dev tree: %m");
goto out;
}
if (ret > 0) {
ret = 0;
goto out;
}
}
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.type != BTRFS_DEV_EXTENT_KEY)
break;
ret = btrfs_del_item(trans, root, &path);
if (ret < 0) {
errno = -ret;
error("failed to delete dev extent %llu, %llu: %m",
key.objectid, key.offset);
goto out;
}
}
out:
btrfs_release_path(&path);
return ret;
}
static int fixup_dev_extents(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
struct btrfs_device *dev;
struct cache_extent *ce;
struct map_lookup *map;
u64 devid = btrfs_stack_device_id(&fs_info->super_copy->dev_item);
int i;
int ret;
ret = remove_all_dev_extents(trans);
if (ret < 0) {
errno = -ret;
error("failed to remove all existing dev extents: %m");
}
dev = btrfs_find_device(fs_info, devid, NULL, NULL);
if (!dev) {
error("faild to find devid %llu", devid);
return -ENODEV;
}
/* Rebuild all dev extents using chunk maps */
for (ce = search_cache_extent(&map_tree->cache_tree, 0); ce;
ce = next_cache_extent(ce)) {
u64 stripe_len;
map = container_of(ce, struct map_lookup, ce);
stripe_len = calc_stripe_length(map->type, ce->size,
map->num_stripes);
for (i = 0; i < map->num_stripes; i++) {
ret = btrfs_insert_dev_extent(trans, dev, ce->start,
stripe_len, map->stripes[i].physical);
if (ret < 0) {
errno = -ret;
error(
"failed to insert dev extent %llu %llu: %m",
devid, map->stripes[i].physical);
goto out;
}
}
}
out:
return ret;
}
static int fixup_chunks_and_devices(struct btrfs_fs_info *fs_info,
struct mdrestore_struct *mdres, off_t dev_size)
{
@ -2226,6 +2327,10 @@ static int fixup_chunks_and_devices(struct btrfs_fs_info *fs_info,
}
fixup_block_groups(fs_info);
ret = fixup_dev_extents(trans);
if (ret < 0)
goto error;
ret = fixup_device_size(trans, mdres, dev_size);
if (ret < 0)
goto error;