On Mon, Jul 09, 2018 at 02:42:02PM +0800, Qu Wenruo wrote: > 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.xu@xxxxxxxxxx> > Links: https://bugzilla.kernel.org/show_bug.cgi?id=200403 Link: > Links: https://bugzilla.kernel.org/show_bug.cgi?id=200407 > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> > --- > 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; > + } > +} There are already too many hardcoded values for the raid profiles, please don't add another one unless really necessary and use existing predefined constants or helpers (eg. nr_data_stripes or btrfs_raid_array). > +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; This variable is only set and never checked. > + 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; 2nd time set > + 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 majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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
