diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/iov_iter.h | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/include/linux/iov_iter.h b/include/linux/iov_iter.h index a223370a59a7..c4aa58032faf 100644 --- a/include/linux/iov_iter.h +++ b/include/linux/iov_iter.h @@ -328,4 +328,51 @@ size_t iterate_and_advance(struct iov_iter *iter, size_t len, void *priv, return iterate_and_advance2(iter, len, priv, NULL, ustep, step); } +/** + * iterate_and_advance_kernel - Iterate over a kernel-internal iterator + * @iter: The iterator to iterate over. + * @len: The amount to iterate over. + * @priv: Data for the step functions. + * @priv2: More data for the step functions. + * @step: Function for other iterators; given kernel addresses. + * + * Iterate over the next part of an iterator, up to the specified length. The + * buffer is presented in segments, which for kernel iteration are broken up by + * physical pages and mapped, with the mapped address being presented. + * + * [!] Note This will only handle BVEC, KVEC, FOLIOQ, XARRAY and DISCARD-type + * iterators; it will not handle UBUF or IOVEC-type iterators. + * + * A step functions, @step, must be provided, one for handling mapped kernel + * addresses and the other is given user addresses which have the potential to + * fault since no pinning is performed. + * + * The step functions are passed the address and length of the segment, @priv, + * @priv2 and the amount of data so far iterated over (which can, for example, + * be added to @priv to point to the right part of a second buffer). The step + * functions should return the amount of the segment they didn't process (ie. 0 + * indicates complete processsing). + * + * This function returns the amount of data processed (ie. 0 means nothing was + * processed and the value of @len means processes to completion). + */ +static __always_inline +size_t iterate_and_advance_kernel(struct iov_iter *iter, size_t len, void *priv, + void *priv2, iov_step_f step) +{ + if (unlikely(iter->count < len)) + len = iter->count; + if (unlikely(!len)) + return 0; + if (iov_iter_is_bvec(iter)) + return iterate_bvec(iter, len, priv, priv2, step); + if (iov_iter_is_kvec(iter)) + return iterate_kvec(iter, len, priv, priv2, step); + if (iov_iter_is_folioq(iter)) + return iterate_folioq(iter, len, priv, priv2, step); + if (iov_iter_is_xarray(iter)) + return iterate_xarray(iter, len, priv, priv2, step); + return iterate_discard(iter, len, priv, priv2, step); +} + #endif /* _LINUX_IOV_ITER_H */ |