[curvefs] When the fs mount is mounted multiple times with different enableSumInDir switches, the xattr information recorded in the metadata will be inaccurate

[cw123]

curvefs 有个特性，为了加快getfattr查询目录下的所有文件的length的长度之和，使用了一个enableSumInDir的特性，当开启这个开关的时候，每次在目录下创建、删除文件，修改文件的长度的时候，都会在目录的attr字段中更新相应的字段。可以在curvefs/src/client/fuse_client.cpp 搜索 enableSumInDir_ 查看对应的实现逻辑。

但是，如果一个fs，挂载了多次，且挂载的时候，有时开启这个特性，有时不开这个特性，就会造成文件的长度信息统计不准。需要想办法避免这种情况。怎么才能在开启这个特性的时候让这个值保持准确？或者，怎么才能在这个统计值不准的时候，不要使用这个值，而是通过遍历所有文件的方式统计数据，来避免拿到错误的数据？

Curvefs has a feature. In order to speed up getfattr to query the sum of the lengths of all files in the directory, a feature of enableSumInDirt is used. When this switch is turned on, every time a file is created or deleted in the directory, the length of the file is modified. At any time, the corresponding field will be updated in the attr field of the directory. You can search enableSumInDir_ in curvefs/src/client/fuse_client.cpp to view the corresponding implementation logic.

However, if an fs is mounted multiple times, and when mounting, sometimes this feature is enabled, and sometimes this feature is not enabled, the statistics of the length information of the file will be inaccurate. A way needs to be found to avoid this. How can I keep this value accurate when this feature is turned on? Or, how can we not use this value when the statistical value is inaccurate, but get the data by traversing all files to avoid getting wrong data?

curvefs/src/client/fuse_client.cpp

enableSumInDir_ = fsInfo_->enablesumindir() && !FLAGS_enableCto;

[tangwz]

assign

[wuhongsong]

Are you having some trouble? If so, please let us know so that we can communicate together @tangwz

[tangwz]

@wuhongsong Sorry I'm too busy this week, I will try to finish it this week.

[wuhongsong]

@tangwz keep going when you have time ？ If you're still busy, you can do it later.

[ilixiaocui]

cc @tangwz Is this issue still being followed up? Did you encounter any problems？

[tangwz]

cc @tangwz Is this issue still being followed up? Did you encounter any problems？

I'm doing this these days. I'm reading the code and think how to do it.

[tangwz]

@ilixiaocui How about if enableSumInDir_ is true in FuseOpInit(), we call CalOneLayerSumInfo() get and record the XATTRFBYTES?

[SeanHai]

@ilixiaocui How about if enableSumInDir_ is true in FuseOpInit(), we call CalOneLayerSumInfo() get and record the XATTRFBYTES?

curve/curvefs/src/client/xattr_manager.cpp

Line 423 in 740debe

CURVEFS_ERROR XattrManager::GetXattr(const char* name, std::string *value,

CalOneLayerSumInfo need calculate all files and directories under the current directory
CalAllLayerSumInfo need calculate all files and directories under the current directory and all subdirs

FastCalOneLayerSumInfo and FastCalAllLayerSumInfo only need get statistics from sumdirs' xattr, because every dir xattr have recorded one layer statistics.

You can read the design document: https://github.com/opencurve/curve/blob/master/docs/cn/curvefs_summary_xattr.md

[tangwz]

So, we can

1. Is enableSumInDir_ is true in FuseOpInit()?
2. If enableSumInDir_ is true, callGetXattr()get theXATTRFBYTES ` and update it in the xattr.

How about this ?

[SeanHai]

So, we can

1. Is enableSumInDir_ is true in FuseOpInit()?
2. If enableSumInDir_ is true, callGetXattr()get theXATTRFBYTES ` and update it in the xattr.

How about this ?

I actually don't understand what your problem is.
The issue is about problem:

1. You turn on 'enableSumInDir_' first, and the summary info will recorded in parent dir xattr after a while. You only need statistic all subdirs' xattr can get the all info under this dir.
2. Then you turn off 'enableSumInDir_', the file number/size etc changed will not record in parent xattr anymore at this period.
3. Finally you turn on 'enableSumInDir_', you get a wrong statistic info form all subdirs' xattr, because missed some changes when step 2(turn off 'enableSumInDir_').

[wuhongsong]

@tangwz Keep talking and figure it out？

[tangwz]

/unassign

[caoxianfei1]

any one want to take it ?

[bit-dance]

I want to try it.

[Cyber-SiKu]

@bit-dance Are you still going on?

[bit-dance]

Yes,and i am trying to test in my local fs but had some build questions and struggled in this step.

[zhanghuidinah]

• This issue has been chosen for community developer activities. Welcome to feel free to try it. After the PR is merged, you will receive a gift package and a certificate as a community contributor.

• Developer Activities Registration Steps please ref [2023 Q2 Developer Activities]: Call For Participation！ #2334 (comment)