On 2019/8/10 上午12:10, Nikolay Borisov wrote:
>
>
> On 9.08.19 г. 9:53 ч., Qu Wenruo wrote:
>> Since kernel is going to reject any root item which is newer than super
>> block generation, we need to provide a way to fix such problem in
>> btrfs-check.
>>
>> This patch addes the ability to report and repair root generation in
>> lowmem mode.
>>
>> This is done by cowing the root node, so we will update the root
>> generation along with the root node generation at commit transaction
>> time.
>>
>> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
>> ---
>> check/mode-common.c | 29 +++++++++++++++++++++++++++++
>> check/mode-common.h | 1 +
>> check/mode-lowmem.c | 16 ++++++++++++++++
>> check/mode-lowmem.h | 1 +
>> 4 files changed, 47 insertions(+)
>>
>> diff --git a/check/mode-common.c b/check/mode-common.c
>> index d5f6c8ef97b1..a5b86a0ac32a 100644
>> --- a/check/mode-common.c
>> +++ b/check/mode-common.c
>> @@ -924,3 +924,32 @@ int check_repair_free_space_inode(struct btrfs_fs_info *fs_info,
>> }
>> return ret;
>> }
>> +
>> +int repair_root_generation(struct btrfs_root *root)
>> +{
>> + struct btrfs_trans_handle *trans;
>> + struct btrfs_path path;
>> + struct btrfs_key key;
>> + int ret;
>> +
>> + trans = btrfs_start_transaction(root, 1);
>> + if (IS_ERR(trans))
>> + return PTR_ERR(trans);
>> +
>> + key.objectid = 0;
>> + key.type = 0;
>> + key.offset = 0;
>> + btrfs_init_path(&path);
>> +
>> + /* Here we only CoW the tree root to update the geneartion */
>> + path.lowest_level = btrfs_header_level(root->node);
>> + root->node->flags |= EXTENT_BAD_TRANSID;
>
> Why do you set EXTENT_BAD_TRANSID? This flag is currently used only in
> read_tree_block to link blocks which have failed ordinary validation to
> the recow_ebs list, and this only happens in case we have a single copy
> for this eb. This list is then processed in the main check logic.
Because we have extra transid check in
btrfs_search_slot()/btrfs_cow_block().
EXTENT_BAD_TRANSID is to suppress such warning.
>
> So repair_root_generation could possibly be as simple as just linking
> root->node to the fs_info->recow_ebs and leave the rest to the existing
> logic?
It doesn't change the root generation.
>
>> +
>> + ret = btrfs_search_slot(trans, root, &key, &path, 0, 1);
>> + if (ret < 0)
>> + return ret;
>> +
>> + btrfs_release_path(&path);
>> + ret = btrfs_commit_transaction(trans, root);
>> + return ret;
>> +}
>> diff --git a/check/mode-common.h b/check/mode-common.h
>> index 4c169c6e3b29..4a3abeb02c81 100644
>> --- a/check/mode-common.h
>> +++ b/check/mode-common.h
>> @@ -155,4 +155,5 @@ static inline bool is_valid_imode(u32 imode)
>> return true;
>> }
>>
>> +int repair_root_generation(struct btrfs_root *root);
>> #endif
>> diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
>> index a2be0e6d7034..bf3b57f5ad2d 100644
>> --- a/check/mode-lowmem.c
>> +++ b/check/mode-lowmem.c
>> @@ -4957,6 +4957,7 @@ static int check_btrfs_root(struct btrfs_root *root, int check_all)
>> struct btrfs_path path;
>> struct node_refs nrefs;
>> struct btrfs_root_item *root_item = &root->root_item;
>> + u64 super_generation = btrfs_super_generation(root->fs_info->super_copy);
>> int ret;
>> int level;
>> int err = 0;
>> @@ -4978,6 +4979,21 @@ static int check_btrfs_root(struct btrfs_root *root, int check_all)
>> level = btrfs_header_level(root->node);
>> btrfs_init_path(&path);
>>
>> + if (btrfs_root_generation(root_item) > super_generation + 1) {
>> + error(
>> + "invalid root generation for root %llu, have %llu expect (0, %llu)",
>> + root->root_key.objectid, btrfs_root_generation(root_item),
>> + super_generation + 1);
>> + err |= INVALID_GENERATION;
>> + if (repair) {
>> + ret = repair_root_generation(root);
>> + if (!ret) {
>> + err &= ~INVALID_GENERATION;
>> + printf("Reset generation for root %llu\n",
>> + root->root_key.objectid);
>> + }
>> + }
>> + }
>> if (btrfs_root_refs(root_item) > 0 ||
>> btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
>> path.nodes[level] = root->node;
>> diff --git a/check/mode-lowmem.h b/check/mode-lowmem.h
>> index d2983fd12eb4..0361fb3382b1 100644
>> --- a/check/mode-lowmem.h
>> +++ b/check/mode-lowmem.h
>> @@ -47,6 +47,7 @@
>> #define INODE_FLAGS_ERROR (1<<23) /* Invalid inode flags */
>> #define DIR_ITEM_HASH_MISMATCH (1<<24) /* Dir item hash mismatch */
>> #define INODE_MODE_ERROR (1<<25) /* Bad inode mode */
>> +#define INVALID_GENERATION (1<<26) /* Generation is too new */
>>
>> /*
>> * Error bit for low memory mode check.
>>
