On 3.07.2018 12:10, Qu Wenruo wrote: > If a crafted btrfs has missing block group items, it could cause > unexpected behavior and breaks our expectation on 1:1 > chunk<->block group mapping. > > Although we added block group -> chunk mapping check, we still need > chunk -> block group mapping check. > > This patch will do extra check to ensure each chunk has its > corresponding block group. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=199847 > Reported-by: Xu Wen <wen.xu@xxxxxxxxxx> > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> > --- > fs/btrfs/extent-tree.c | 52 +++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 51 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 82b446f014b9..746095034ca2 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -10038,6 +10038,56 @@ static int check_exist_chunk(struct btrfs_fs_info *fs_info, u64 start, u64 len, > return ret; > } > > +/* > + * Iterate all chunks and verify each of them has corresponding block group > + */ > +static int check_chunk_block_group_mappings(struct btrfs_fs_info *fs_info) > +{ > + struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree; > + struct extent_map *em; > + struct btrfs_block_group_cache *bg; > + u64 start = 0; > + int ret = 0; > + > + while (1) { > + read_lock(&map_tree->map_tree.lock); > + em = lookup_extent_mapping(&map_tree->map_tree, start, > + (u64)-1 - start); len parameter of lookup_extent_mapping eventually ends up in range_end. Meaning it will just return -1. Why not use just -1 for len. Looking at the rest of the code this seems to be the convention. But then there are several places where 1 is passed as well. Hm, in any case a single number is simpler than an expression. > + read_unlock(&map_tree->map_tree.lock); > + if (!em) > + break; > + > + bg = btrfs_lookup_block_group(fs_info, em->start); > + if (!bg) { > + btrfs_err_rl(fs_info, > + "chunk start=%llu len=%llu doesn't have corresponding block group", > + em->start, em->len); > + ret = -ENOENT; > + free_extent_map(em); > + break; > + } > + if (bg->key.objectid != em->start || > + bg->key.offset != em->len || > + (bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK) != > + (em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK)) { > + btrfs_err_rl(fs_info, > +"chunk start=%llu len=%llu flags=0x%llx doesn't match with block group start=%llu len=%llu flags=0x%llx", > + em->start, em->len, > + em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK, > + bg->key.objectid, bg->key.offset, > + bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK); > + ret = -EUCLEAN; > + free_extent_map(em); > + btrfs_put_block_group(bg); > + break; > + } > + start = em->start + em->len; > + free_extent_map(em); > + btrfs_put_block_group(bg); > + } > + return ret; > +} > + > int btrfs_read_block_groups(struct btrfs_fs_info *info) > { > struct btrfs_path *path; > @@ -10227,7 +10277,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) > > btrfs_add_raid_kobjects(info); > init_global_block_rsv(info); > - ret = 0; > + ret = check_chunk_block_group_mappings(info); Rather than doing that can we just get the count of chunks. Then if we have as many chunks as BG have been read in and we know the BG -> chunk mapping check has passed we can assume that chunks also map to BG without going through all chunks. > error: > btrfs_free_path(path); > return ret; > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
