Re: [PATCH 1/3] btrfs-progs: check/lowmem: Add check and repair for invalid inode generation

Qu Wenruo
2019-09-30T12:24:52Z

On 2019/9/30 下午7:36, Nikolay Borisov wrote:
>
>
> On 24.09.19 г. 11:11 ч., Qu Wenruo wrote:
>> There are at least two bug reports of kernel tree-checker complaining
>> about invalid inode generation.
>>
>> All offending inodes seem to be caused by old kernel around 2014, with
>> inode generation overflow.
>>
>> So add such check and repair ability to lowmem mode check first.
>>
>> This involves:
>> - Calculate the inode generation upper limit
>> If it's an inode from log tree, then the upper limit is
>> super_generation + 1, otherwise it's super_generation.
>>
>> - Check if the inode generation is larger than the upper limit
>>
>> - Repair by resetting inode generation to current transaction
>> generation
>>
>> Reported-by: Charles Wright <charles.v.wright@gmail.com>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>
> Tested-by: Nikolay Borisov <nborisov@suse.com>
>
> There is one small nit with the assert once rectified you can add:
>
> Reviewed-by: Nikolay Borisov <nborisov@suse.com>
>
>> ---
>> check/mode-lowmem.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 76 insertions(+)
>>
>> diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
>> index 5f7f101d..7af29ba9 100644
>> --- a/check/mode-lowmem.c
>> +++ b/check/mode-lowmem.c
>> @@ -2472,6 +2472,59 @@ static bool has_orphan_item(struct btrfs_root *root, u64 ino)
>> return false;
>> }
>>
>> +static int repair_inode_gen_lowmem(struct btrfs_root *root,
>> + struct btrfs_path *path)
>> +{
>> + struct btrfs_trans_handle *trans;
>> + struct btrfs_inode_item *ii;
>> + struct btrfs_key key;
>> + u64 transid;
>> + int ret;
>> +
>> + trans = btrfs_start_transaction(root, 1);
>> + if (IS_ERR(trans)) {
>> + ret = PTR_ERR(trans);
>> + errno = -ret;
>> + error("failed to start transaction for inode gen repair: %m");
>> + return ret;
>> + }
>> + transid = trans->transid;
>
>> + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
>> + ASSERT(key.type == BTRFS_INODE_ITEM_KEY);
>
> nit: This function's sole caller, check_inode_item, is guaranteed to be
> called with a path pointing to BTRFS_INODE_ITEM_KEY thanks to the logic
> in the 'for' loop in process_one_leaf. This renders the assert
> redundant. At the very least I think it should be moved to
> check_inode_item.

Yes, the ASSERT() doesn't make much sense by itself.

However I still believe it won't be a problem.

It's compiler's job to remove such dead ASSERT(), but for human reader,
I still believe this ASSERT() could still make sense, especially when
the caller or callee can get more and more complex.

Thanks,
Qu

>
>> +
>> + btrfs_release_path(path);
>> +
>> + ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
>> + if (ret > 0) {
>> + ret = -ENOENT;
>> + error("no inode item found for ino %llu", key.objectid);
>> + goto error;
>> + }
>> + if (ret < 0) {
>> + errno = -ret;
>> + error("failed to find inode item for ino %llu: %m",
>> + key.objectid);
>> + goto error;
>> + }
>> + ii = btrfs_item_ptr(path->nodes[0], path->slots[0],
>> + struct btrfs_inode_item);
>> + btrfs_set_inode_generation(path->nodes[0], ii, trans->transid);
>> + btrfs_mark_buffer_dirty(path->nodes[0]);
>> + ret = btrfs_commit_transaction(trans, root);
>> + if (ret < 0) {
>> + errno = -ret;
>> + error("failed to commit transaction: %m");
>> + goto error;
>> + }
>> + printf("reseting inode generation to %llu for ino %llu\n",
>> + transid, key.objectid);
>> + return ret;
>> +
>> +error:
>> + btrfs_abort_transaction(trans, ret);
>> + return ret;
>> +}
>> +
>> /*
>> * Check INODE_ITEM and related ITEMs (the same inode number)
>> * 1. check link count
>> @@ -2487,6 +2540,7 @@ static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path)
>> struct btrfs_inode_item *ii;
>> struct btrfs_key key;
>> struct btrfs_key last_key;
>> + struct btrfs_super_block *super = root->fs_info->super_copy;
>> u64 inode_id;
>> u32 mode;
>> u64 flags;
>> @@ -2497,6 +2551,8 @@ static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path)
>> u64 refs = 0;
>> u64 extent_end = 0;
>> u64 extent_size = 0;
>> + u64 generation;
>> + u64 gen_uplimit;
>> unsigned int dir;
>> unsigned int nodatasum;
>> bool is_orphan = false;
>> @@ -2527,6 +2583,7 @@ static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path)
>> flags = btrfs_inode_flags(node, ii);
>> dir = imode_to_type(mode) == BTRFS_FT_DIR;
>> nlink = btrfs_inode_nlink(node, ii);
>> + generation = btrfs_inode_generation(node, ii);
>> nodatasum = btrfs_inode_flags(node, ii) & BTRFS_INODE_NODATASUM;
>>
>> if (!is_valid_imode(mode)) {
>> @@ -2540,6 +2597,25 @@ static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path)
>> }
>> }
>>
>> + if (btrfs_super_log_root(super) != 0 &&
>> + root->objectid == BTRFS_TREE_LOG_OBJECTID)
>> + gen_uplimit = btrfs_super_generation(super) + 1;
>> + else
>> + gen_uplimit = btrfs_super_generation(super);
>> +
>> + if (generation > gen_uplimit) {
>> + error(
>> + "invalid inode generation for ino %llu, have %llu expect [0, %llu)",
>> + inode_id, generation, gen_uplimit);
>> + if (repair) {
>> + ret = repair_inode_gen_lowmem(root, path);
>> + if (ret < 0)
>> + err |= INVALID_GENERATION;
>> + } else {
>> + err |= INVALID_GENERATION;
>> + }
>> +
>> + }
>> if (S_ISLNK(mode) &&
>> flags & (BTRFS_INODE_IMMUTABLE | BTRFS_INODE_APPEND)) {
>> err |= INODE_FLAGS_ERROR;
>>