> IORING_OP_GETDENTS behaves much like getdents64(2) and takes the same
> arguments, but with a small twist: it takes an additional offset
> argument, and reading from the specified directory starts at the given
> offset.
>
> For the first IORING_OP_GETDENTS call on a directory, the offset
> parameter can be set to zero, and for subsequent calls, it can be
> set to the ->d_off field of the last struct linux_dirent64 returned
> by the previous IORING_OP_GETDENTS call.
>
> Internally, if necessary, IORING_OP_GETDENTS will vfs_llseek() to
> the right directory position before calling vfs_getdents().
For my envisioned use case it would be important to support reading from
the current file position when offset == -1 (IORING_FEAT_RW_CUR_POS).
Among other things, this would let me fully read a directory with fewer
round-trips. Normally after the first getdents(), another one must be
issued to distinguish between EOF and a short first read. It would be
nice to do both calls with linked SQEs so I could immediately know that
I've reached the end of the directory.
> IORING_OP_GETDENTS may or may not update the specified directory's
> file offset, and the file offset should not be relied upon having
> any particular value during or after an IORING_OP_GETDENTS call.
Obviously for the above to work, we'd have to get rid of this
limitation. Is that possible?
