Re: [PATCH/RFC v3 01/13] Move index v2 specific functions to their own file

> If you found that an entry you read halfway has an inconsistent crc,
> and if you suspect that is because somebody else was writing to the
> same index, it is a _sure_ sign that you are not alone, and all the
> entries you read so far to the core, even if they weren't touched by
> that sombody else when you read them, may be stale, and worse yet,
> what you are going to read may be inconsistent with what you've read
> and have in-core (e.g. you may have read "f" before somebody else
> that is racing with you have turned it into a directory, and your
> next read may find "f/d" in the index without crc error).
>
> One sane way to avoid reading such an inconsistent state may be to
> redo this whole function, starting from the part that calls mmap().
> IOW,
>
> 	do {
> 		fd = open()
> 		mmap = xmmap(fd);
> 		close(fd);
>                 verify_various_fields(mmap);
>                 status = istate->ops->read_index(istate, mmap, mmap_size));
> 	} while (status == READ_AGAIN);
>
> I do not think the "pass fd around so that we can redo the mapping
> deep inside the callchain" is either a good idea or necessary.