On 2019/10/17 上午11:23, Anand Jain wrote: > On 10/8/19 12:49 PM, Qu Wenruo wrote: >> This patch does the following refactor: >> - Refactor parameter from @root to @fs_info >> >> - Refactor the large loop body into another function >> Now we have a helper function, read_one_block_group(), to handle >> block group cache and space info related routine. >> >> - Refactor the return value >> Even we have the code handling ret > 0 from find_first_block_group(), >> it never works, as when there is no more block group, >> find_first_block_group() just return -ENOENT other than 1. > > > Can it be separated into patches? My concern is as it alters the return > value of the rescue command. So we shall have clarity of a discrete > patch to blame. Otherwise I agree its a good change.
No problem.
What about 3 patches split by the mentioned 3 refactors?
>
>
>> This is super confusing, it's almost a mircle it even works.
>>
>> Signed-off-by: Qu Wenruo <w...@suse.com>
>> ---
>> ctree.h | 2 +-
>> disk-io.c | 9 ++-
>> extent-tree.c | 160 ++++++++++++++++++++++++++++----------------------
>> 3 files changed, 97 insertions(+), 74 deletions(-)
>>
>> diff --git a/ctree.h b/ctree.h
>> index 8c7b3cb40151..2899de358613 100644
>> --- a/ctree.h
>> +++ b/ctree.h
>> @@ -2550,7 +2550,7 @@ int update_space_info(struct btrfs_fs_info
>> *info, u64 flags,
>> u64 total_bytes, u64 bytes_used,
>> struct btrfs_space_info **space_info);
>> int btrfs_free_block_groups(struct btrfs_fs_info *info);
>> -int btrfs_read_block_groups(struct btrfs_root *root);
>> +int btrfs_read_block_groups(struct btrfs_fs_info *info);
>> struct btrfs_block_group_cache *
>> btrfs_add_block_group(struct btrfs_fs_info *fs_info, u64 bytes_used,
>> u64 type,
>> u64 chunk_offset, u64 size);
>> diff --git a/disk-io.c b/disk-io.c
>> index be44eead5cef..8978f0cb60c7 100644
>> --- a/disk-io.c
>> +++ b/disk-io.c
>> @@ -983,14 +983,17 @@ int btrfs_setup_all_roots(struct btrfs_fs_info
>> *fs_info, u64 root_tree_bytenr,
>> fs_info->last_trans_committed = generation;
>> if (extent_buffer_uptodate(fs_info->extent_root->node) &&
>> !(flags & OPEN_CTREE_NO_BLOCK_GROUPS)) {
>> - ret = btrfs_read_block_groups(fs_info->tree_root);
>> + ret = btrfs_read_block_groups(fs_info);
>> /*
>> * If we don't find any blockgroups (ENOENT) we're either
>> * restoring or creating the filesystem, where it's expected,
>> * anything else is error
>> */
>> - if (ret != -ENOENT)
>> - return -EIO;
>> + if (ret < 0 && ret != -ENOENT) {
>> + errno = -ret;
>> + error("failed to read block groups: %m");
>> + return ret;
>> + }
>> }
>
>
> As mentioned this alters the rescue command semantics as show below.
> Earlier we had only -EIO as error now its much more and accurate
> which is good. fstests is fine but anything else?
>
> cmd_rescue_chunk_recover()
> btrfs_recover_chunk_tree()
> open_ctree_with_broken_chunk()
> btrfs_setup_all_roots()
I'm not sure if I got the point.
Although btrfs_setup_all_roots() get called in above call chain, it
doesn't have any special handling of -EIO or others.
It just reads the extent tree root.
Would you mind to explain a little more?
Thanks,
Qu
>
> Thanks, Anand
>
>> key.objectid = BTRFS_FS_TREE_OBJECTID;
>> diff --git a/extent-tree.c b/extent-tree.c
>> index 19d1ea0df570..9713d627764c 100644
>> --- a/extent-tree.c
>> +++ b/extent-tree.c
>> @@ -2607,6 +2607,13 @@ int btrfs_free_block_groups(struct
>> btrfs_fs_info *info)
>> return 0;
>> }
>> +/*
>> + * Find a block group which starts >= @key->objectid in extent tree.
>> + *
>> + * Return 0 for found
>> + * Retrun >0 for not found
>> + * Return <0 for error
>> + */
>> static int find_first_block_group(struct btrfs_root *root,
>> struct btrfs_path *path, struct btrfs_key *key)
>> {
>> @@ -2636,36 +2643,95 @@ static int find_first_block_group(struct
>> btrfs_root *root,
>> return 0;
>> path->slots[0]++;
>> }
>> - ret = -ENOENT;
>> + ret = 1;
>> error:
>> return ret;
>> }
>> -int btrfs_read_block_groups(struct btrfs_root *root)
>> +/*
>> + * Helper function to read out one BLOCK_GROUP_ITEM and insert it into
>> + * block group cache.
>> + *
>> + * Return 0 if nothing wrong (either insert the bg cache or skip 0
>> sized bg)
>> + * Return <0 for error.
>> + */
>> +static int read_one_block_group(struct btrfs_fs_info *fs_info,
>> + struct btrfs_path *path)
>> {
>> - struct btrfs_path *path;
>> - int ret;
>> - int bit;
>> - struct btrfs_block_group_cache *cache;
>> - struct btrfs_fs_info *info = root->fs_info;
>> + struct extent_io_tree *block_group_cache =
>> &fs_info->block_group_cache;
>> + struct extent_buffer *leaf = path->nodes[0];
>> struct btrfs_space_info *space_info;
>> - struct extent_io_tree *block_group_cache;
>> + struct btrfs_block_group_cache *cache;
>> struct btrfs_key key;
>> - struct btrfs_key found_key;
>> - struct extent_buffer *leaf;
>> + int slot = path->slots[0];
>> + int bit = 0;
>> + int ret;
>> - block_group_cache = &info->block_group_cache;
>> + btrfs_item_key_to_cpu(leaf, &key, slot);
>> + ASSERT(key.type == BTRFS_BLOCK_GROUP_ITEM_KEY);
>> +
>> + /*
>> + * Skip 0 sized block group, don't insert them into block
>> + * group cache tree, as its length is 0, it won't get
>> + * freed at close_ctree() time.
>> + */
>> + if (key.offset == 0)
>> + return 0;
>> +
>> + cache = kzalloc(sizeof(*cache), GFP_NOFS);
>> + if (!cache)
>> + return -ENOMEM;
>> + read_extent_buffer(leaf, &cache->item,
>> + btrfs_item_ptr_offset(leaf, slot),
>> + sizeof(cache->item));
>> + memcpy(&cache->key, &key, sizeof(key));
>> + cache->cached = 0;
>> + cache->pinned = 0;
>> + cache->flags = btrfs_block_group_flags(&cache->item);
>> + if (cache->flags & BTRFS_BLOCK_GROUP_DATA) {
>> + bit = BLOCK_GROUP_DATA;
>> + } else if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
>> + bit = BLOCK_GROUP_SYSTEM;
>> + } else if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
>> + bit = BLOCK_GROUP_METADATA;
>> + }
>> + set_avail_alloc_bits(fs_info, cache->flags);
>> + if (btrfs_chunk_readonly(fs_info, cache->key.objectid))
>> + cache->ro = 1;
>> + exclude_super_stripes(fs_info, cache);
>> +
>> + ret = update_space_info(fs_info, cache->flags, cache->key.offset,
>> + btrfs_block_group_used(&cache->item),
>> + &space_info);
>> + if (ret < 0) {
>> + free(cache);
>> + return ret;
>> + }
>> + cache->space_info = space_info;
>> +
>> + set_extent_bits(block_group_cache, cache->key.objectid,
>> + cache->key.objectid + cache->key.offset - 1,
>> + bit | EXTENT_LOCKED);
>> + set_state_private(block_group_cache, cache->key.objectid,
>> + (unsigned long)cache);
>> + return 0;
>> +}
>> - root = info->extent_root;
>> +int btrfs_read_block_groups(struct btrfs_fs_info *fs_info)
>> +{
>> + struct btrfs_path path;
>> + struct btrfs_root *root;
>> + int ret;
>> + struct btrfs_key key;
>> +
>> + root = fs_info->extent_root;
>> key.objectid = 0;
>> key.offset = 0;
>> key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
>> - path = btrfs_alloc_path();
>> - if (!path)
>> - return -ENOMEM;
>> + btrfs_init_path(&path);
>> while(1) {
>> - ret = find_first_block_group(root, path, &key);
>> + ret = find_first_block_group(root, &path, &key);
>> if (ret > 0) {
>> ret = 0;
>> goto error;
>> @@ -2673,67 +2739,21 @@ int btrfs_read_block_groups(struct btrfs_root
>> *root)
>> if (ret != 0) {
>> goto error;
>> }
>> - leaf = path->nodes[0];
>> - btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
>> + btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
>> - cache = kzalloc(sizeof(*cache), GFP_NOFS);
>> - if (!cache) {
>> - ret = -ENOMEM;
>> + ret = read_one_block_group(fs_info, &path);
>> + if (ret < 0)
>> goto error;
>> - }
>> - read_extent_buffer(leaf, &cache->item,
>> - btrfs_item_ptr_offset(leaf, path->slots[0]),
>> - sizeof(cache->item));
>> - memcpy(&cache->key, &found_key, sizeof(found_key));
>> - cache->cached = 0;
>> - cache->pinned = 0;
>> - key.objectid = found_key.objectid + found_key.offset;
>> - if (found_key.offset == 0)
>> + if (key.offset == 0)
>> key.objectid++;
>> - btrfs_release_path(path);
>> -
>> - /*
>> - * Skip 0 sized block group, don't insert them into block
>> - * group cache tree, as its length is 0, it won't get
>> - * freed at close_ctree() time.
>> - */
>> - if (found_key.offset == 0) {
>> - free(cache);
>> - continue;
>> - }
>> -
>> - cache->flags = btrfs_block_group_flags(&cache->item);
>> - bit = 0;
>> - if (cache->flags & BTRFS_BLOCK_GROUP_DATA) {
>> - bit = BLOCK_GROUP_DATA;
>> - } else if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
>> - bit = BLOCK_GROUP_SYSTEM;
>> - } else if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
>> - bit = BLOCK_GROUP_METADATA;
>> - }
>> - set_avail_alloc_bits(info, cache->flags);
>> - if (btrfs_chunk_readonly(info, cache->key.objectid))
>> - cache->ro = 1;
>> -
>> - exclude_super_stripes(info, cache);
>> -
>> - ret = update_space_info(info, cache->flags, found_key.offset,
>> - btrfs_block_group_used(&cache->item),
>> - &space_info);
>> - BUG_ON(ret);
>> - cache->space_info = space_info;
>> -
>> - /* use EXTENT_LOCKED to prevent merging */
>> - set_extent_bits(block_group_cache, found_key.objectid,
>> - found_key.objectid + found_key.offset - 1,
>> - bit | EXTENT_LOCKED);
>> - set_state_private(block_group_cache, found_key.objectid,
>> - (unsigned long)cache);
>> + else
>> + key.objectid = key.objectid + key.offset;
>> + btrfs_release_path(&path);
>> }
>> ret = 0;
>> error:
>> - btrfs_free_path(path);
>> + btrfs_release_path(&path);
>> return ret;
>> }
>>
>
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