This patch will introduce chunk <-> dev extent mapping check, to protect us against invalid dev extents or chunks.
Since chunk mapping is the fundamental infrastructure of btrfs, extra check at mount time could prevent a lot of unexpected behavior (BUG_ON). Reported-by: Xu Wen <wen...@gatech.edu> Links: https://bugzilla.kernel.org/show_bug.cgi?id=200403 Links: https://bugzilla.kernel.org/show_bug.cgi?id=200407 Signed-off-by: Qu Wenruo <w...@suse.com> --- fs/btrfs/disk-io.c | 7 ++ fs/btrfs/volumes.c | 173 +++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/volumes.h | 2 + 3 files changed, 182 insertions(+) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 205092dc9390..068ca7498e94 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3075,6 +3075,13 @@ int open_ctree(struct super_block *sb, fs_info->generation = generation; fs_info->last_trans_committed = generation; + ret = btrfs_verify_dev_extents(fs_info); + if (ret) { + btrfs_err(fs_info, + "failed to verify dev extents against chunks: %d", + ret); + goto fail_block_groups; + } ret = btrfs_recover_balance(fs_info); if (ret) { btrfs_err(fs_info, "failed to recover balance: %d", ret); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index e6a8e4aabc66..05e418cb37f3 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -6440,6 +6440,7 @@ static int read_one_chunk(struct btrfs_fs_info *fs_info, struct btrfs_key *key, map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk); map->type = btrfs_chunk_type(leaf, chunk); map->sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk); + map->verified_stripes = 0; for (i = 0; i < num_stripes; i++) { map->stripes[i].physical = btrfs_stripe_offset_nr(leaf, chunk, i); @@ -7295,3 +7296,175 @@ void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info) fs_devices = fs_devices->seed; } } + +static u64 calc_stripe_length(u64 type, u64 chunk_len, int num_stripes) +{ + switch (type & BTRFS_BLOCK_GROUP_PROFILE_MASK) { + case BTRFS_BLOCK_GROUP_RAID0: + return div_u64(chunk_len, num_stripes); + case BTRFS_BLOCK_GROUP_RAID10: + return div_u64(chunk_len * 2, num_stripes); + case BTRFS_BLOCK_GROUP_RAID5: + return div_u64(chunk_len, num_stripes - 1); + case BTRFS_BLOCK_GROUP_RAID6: + return div_u64(chunk_len, num_stripes - 2); + default: + return chunk_len; + } +} +static int verify_one_dev_extent(struct btrfs_fs_info *fs_info, + u64 chunk_offset, u64 devid, + u64 physical_offset, u64 physical_len) +{ + struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree; + struct extent_map *em; + struct map_lookup *map; + u64 stripe_len; + bool found = false; + int ret = 0; + int i; + + read_lock(&em_tree->lock); + em = lookup_extent_mapping(em_tree, chunk_offset, 1); + read_unlock(&em_tree->lock); + + if (!em) { + ret = -EUCLEAN; + btrfs_err(fs_info, + "dev extent (%llu, %llu) doesn't have corresponding chunk", + devid, physical_offset); + goto out; + } + + map = em->map_lookup; + stripe_len = calc_stripe_length(map->type, em->len, map->num_stripes); + if (physical_len != stripe_len) { + btrfs_err(fs_info, +"dev extent (%llu, %llu) length doesn't match with chunk %llu, have %llu expect %llu", + devid, physical_offset, em->start, physical_len, + stripe_len); + ret = -EUCLEAN; + goto out; + } + + for (i = 0; i < map->num_stripes; i++) { + if (map->stripes[i].dev->devid == devid && + map->stripes[i].physical == physical_offset) { + found = true; + if (map->verified_stripes >= map->num_stripes) { + btrfs_err(fs_info, + "too many dev extent for chunk %llu is detected", + em->start); + ret = -EUCLEAN; + goto out; + } + map->verified_stripes++; + break; + } + } +out: + free_extent_map(em); + return ret; +} + +static int verify_chunk_dev_extent_mapping(struct btrfs_fs_info *fs_info) +{ + struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree; + struct extent_map *em; + struct rb_node *node; + int ret = 0; + + read_lock(&em_tree->lock); + for (node = rb_first(&em_tree->map); node; node = rb_next(node)) { + em = rb_entry(node, struct extent_map, rb_node); + if (em->map_lookup->num_stripes != + em->map_lookup->verified_stripes) { + btrfs_err(fs_info, + "chunk %llu has missing dev extent, have %d expect %d", + em->start, em->map_lookup->verified_stripes, + em->map_lookup->num_stripes); + ret = -EUCLEAN; + goto out; + } + } +out: + read_unlock(&em_tree->lock); + return ret; +} + +/* + * Ensure all dev extents are mapped to correct chunk. + * Or later chunk allocation/free would cause unexpected behavior. + * + * NOTE: This will iterate through the whole device tree, which should be + * at the same size level of chunk tree. + * This would increase mount time by a tiny fraction. + */ +int btrfs_verify_dev_extents(struct btrfs_fs_info *fs_info) +{ + struct btrfs_path *path; + struct btrfs_root *root = fs_info->dev_root; + struct btrfs_key key; + int ret = 0; + + key.objectid = 1; + key.type = BTRFS_DEV_EXTENT_KEY; + key.offset = 0; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + path->reada = READA_FORWARD; + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) + goto out; + + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { + ret = btrfs_next_item(root, path); + if (ret < 0) + goto out; + /* No dev extents at all? Not good */ + if (ret > 0) { + ret = -EUCLEAN; + goto out; + } + } + while (1) { + struct extent_buffer *leaf = path->nodes[0]; + struct btrfs_dev_extent *dext; + int slot = path->slots[0]; + u64 chunk_offset; + u64 physical_offset; + u64 physical_len; + u64 devid; + + btrfs_item_key_to_cpu(leaf, &key, slot); + if (key.type != BTRFS_DEV_EXTENT_KEY) + break; + devid = key.objectid; + physical_offset = key.offset; + + dext = btrfs_item_ptr(leaf, slot, struct btrfs_dev_extent); + chunk_offset = btrfs_dev_extent_chunk_offset(leaf, dext); + physical_len = btrfs_dev_extent_length(leaf, dext); + + ret = verify_one_dev_extent(fs_info, chunk_offset, devid, + physical_offset, physical_len); + if (ret < 0) + goto out; + ret = btrfs_next_item(root, path); + if (ret < 0) + goto out; + if (ret > 0) { + ret = 0; + break; + } + } + + /* Ensure all chunks have corresponding dev extents */ + ret = verify_chunk_dev_extent_mapping(fs_info); +out: + btrfs_free_path(path); + return ret; +} diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 6d4f38ad9f5c..4301bf2d0534 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -345,6 +345,7 @@ struct map_lookup { u64 stripe_len; int num_stripes; int sub_stripes; + int verified_stripes; /* For mount time dev extent verification */ struct btrfs_bio_stripe stripes[]; }; @@ -559,5 +560,6 @@ void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info); void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info); bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info, struct btrfs_device *failing_dev); +int btrfs_verify_dev_extents(struct btrfs_fs_info *fs_info); #endif -- 2.18.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
