On 2018/11/7 下午2:28, Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx> wrote:
>
>
> On 10/24/2018 8:34 AM, Qu Wenruo wrote:
>>
>> On 2018/10/23 下午5:41, Su Yue wrote:
>>> From: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx>
>>>
>>> It may cost more time to search all extent data of correspond files but
>>> should not influence total speed too much cause that only corrupted
>>> extent items are participated in.
>> Sorry, I didn't really get the point of the modification from the commit
>> message.
>>
>> Would you please explain the purpose of this patch first?
>>
>> Thanks,
>> Qu
>
> In find_possible_backrefs() function:
>
> key.objectid = dback->owner;
> key.type = BTRFS_EXTENT_DATA_KEY;
> key.offset = dback->offset;//
> ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
>
> 'dback->offset' is not the offset in file range, we'll find wrong file
> extent.
Now this makes sense.
The original commit message doesn't touch this part, and focused on the
side effect, not the problem itself.
Please update the commit message.
Thanks,
Qu
>
> Thanks,
>
> Su
>
>>> Signed-off-by: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx>
>>> ---
>>> check/main.c | 110 ++++++++++++++++++++++++++++++++++++++++++---------
>>> 1 file changed, 92 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/check/main.c b/check/main.c
>>> index bd1f322e0f12..90d9fd570287 100644
>>> --- a/check/main.c
>>> +++ b/check/main.c
>>> @@ -7015,6 +7015,89 @@ out:
>>> return ret ? ret : nr_del;
>>> }
>>> +/*
>>> + * Based extent backref item, we find all file extent items in the
>>> fs tree. By
>>> + * the info we can rebuild the extent backref item
>>> + */
>>> +static int __find_possible_backrefs(struct btrfs_root *root,
>>> + u64 owner, u64 offset, u64 bytenr, u64 *refs_ret,
>>> + u64 *bytes_ret)
>>> +{
>>> + int ret = 0;
>>> + struct btrfs_path path;
>>> + struct btrfs_key key;
>>> + struct btrfs_key found_key;
>>> + struct btrfs_file_extent_item *fi;
>>> + struct extent_buffer *leaf;
>>> + u64 backref_offset, disk_bytenr;
>>> + int slot;
>>> +
>>> + btrfs_init_path(&path);
>>> +
>>> + key.objectid = owner;
>>> + key.type = BTRFS_INODE_ITEM_KEY;
>>> + key.offset = 0;
>>> +
>>> + ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
>>> + if (ret > 0)
>>> + ret = -ENOENT;
>>> + if (ret) {
>>> + btrfs_release_path(&path);
>>> + return ret;
>>> + }
>>> +
>>> + btrfs_release_path(&path);
>>> +
>>> + key.objectid = owner;
>>> + key.type = BTRFS_EXTENT_DATA_KEY;
>>> + key.offset = 0;
>>> +
>>> + ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
>>> + if (ret < 0) {
>>> + btrfs_release_path(&path);
>>> + return ret;
>>> + }
>>> +
>>> + while (1) {
>>> + leaf = path.nodes[0];
>>> + slot = path.slots[0];
>>> +
>>> + if (slot >= btrfs_header_nritems(leaf)) {
>>> + ret = btrfs_next_leaf(root, &path);
>>> + if (ret) {
>>> + if (ret > 0)
>>> + ret = 0;
>>> + break;
>>> + }
>>> +
>>> + leaf = path.nodes[0];
>>> + slot = path.slots[0];
>>> + }
>>> +
>>> + btrfs_item_key_to_cpu(leaf, &found_key, slot);
>>> + if ((found_key.objectid != owner) ||
>>> + (found_key.type != BTRFS_EXTENT_DATA_KEY))
>>> + break;
>>> +
>>> + fi = btrfs_item_ptr(leaf, slot,
>>> + struct btrfs_file_extent_item);
>>> +
>>> + backref_offset = found_key.offset -
>>> + btrfs_file_extent_offset(leaf, fi);
>>> + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
>>> + *bytes_ret = btrfs_file_extent_disk_num_bytes(leaf,
>>> + fi);
>>> + if ((disk_bytenr == bytenr) &&
>>> + (backref_offset == offset)) {
>>> + (*refs_ret)++;
>>> + }
>>> + path.slots[0]++;
>>> + }
>>> +
>>> + btrfs_release_path(&path);
>>> + return ret;
>>> +}
>>> +
>>> static int find_possible_backrefs(struct btrfs_fs_info *info,
>>> struct btrfs_path *path,
>>> struct cache_tree *extent_cache,
>>> @@ -7024,9 +7107,9 @@ static int find_possible_backrefs(struct
>>> btrfs_fs_info *info,
>>> struct extent_backref *back, *tmp;
>>> struct data_backref *dback;
>>> struct cache_extent *cache;
>>> - struct btrfs_file_extent_item *fi;
>>> struct btrfs_key key;
>>> u64 bytenr, bytes;
>>> + u64 refs;
>>> int ret;
>>> rbtree_postorder_for_each_entry_safe(back, tmp,
>>> @@ -7054,24 +7137,15 @@ static int find_possible_backrefs(struct
>>> btrfs_fs_info *info,
>>> if (IS_ERR(root))
>>> return PTR_ERR(root);
>>> - key.objectid = dback->owner;
>>> - key.type = BTRFS_EXTENT_DATA_KEY;
>>> - key.offset = dback->offset;
>>> - ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
>>> - if (ret) {
>>> - btrfs_release_path(path);
>>> - if (ret < 0)
>>> - return ret;
>>> - /* Didn't find it, we can carry on */
>>> - ret = 0;
>>> + refs = 0;
>>> + bytes = 0;
>>> + ret = __find_possible_backrefs(root, dback->owner,
>>> + dback->offset, rec->start, &refs, &bytes);
>>> + if (ret)
>>> continue;
>>> - }
>>> - fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
>>> - struct btrfs_file_extent_item);
>>> - bytenr = btrfs_file_extent_disk_bytenr(path->nodes[0], fi);
>>> - bytes = btrfs_file_extent_disk_num_bytes(path->nodes[0], fi);
>>> - btrfs_release_path(path);
>>> + bytenr = rec->start;
>>> +
>>> cache = lookup_cache_extent(extent_cache, bytenr, 1);
>>> if (cache) {
>>> struct extent_record *tmp;
>>> @@ -7090,7 +7164,7 @@ static int find_possible_backrefs(struct
>>> btrfs_fs_info *info,
>>> continue;
>>> }
>>> - dback->found_ref += 1;
>>> + dback->found_ref += refs;
>>> dback->disk_bytenr = bytenr;
>>> dback->bytes = bytes;
>>>
>>
>
>
>
