Option to control file layout/packing order (similar to SquashFS --sort)

[lucascdn]

Is there a way to control the layout of files on disk when building an EROFS image? SquashFS, for example, has the -sort / --sort-file options that let you fine-tune how data is clustered, and I was wondering if EROFS provides something similar.

Thanks!

[hsiangkao]

Hi @lucascdn ! Of course the data layout can be controlled but there is no such functionality for now.
Could you elaborate your use case in details?
I ask that because erofs supports data deduplication so the extents in a single inode can be nonconsecutive (which is unlike squashfs, because squashfs doesn't support finer data deduplication), so I'm not sure a file-based priority file is enough for all future use cases.

[sudobash1]

Does --tar=f --sort=none work for ordering the file data?

I have a possible use case:

I am generating an erofs with lots of small (1k - 20k) files with in a single directory. Their names are hashes, so they are essentially randomly ordered. When I add a more files and recreate erofs, I would like the new files to be appended to the end (or at least not interspersed among the prior files). This way tools like rsync and zchunk will have all the new data in one place instead of spread out.

I don't know if this is necessary, but it is something that I have been looking into.

Edit: I have also wondered about --incremental=data builds and if they would have a similar effect.

[hsiangkao]

Does --tar=f --sort=none work for ordering the file data?

I have a possible use case:

I am generating an erofs with lots of small (1k - 20k) files with in a single directory. Their names are hashes, so they are essentially randomly ordered. When I add a more files and recreate erofs, I would like the new files to be appended to the end (or at least not interspersed among the prior files). This way tools like rsync and zchunk will have all the new data in one place instead of spread out.

I don't know if this is necessary, but it is something that I have been looking into.

Edit: I have also wondered about --incremental=data builds and if they would have a similar effect.

You could try if --incremental=data works for you