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SubjectRe: [PATCH v9 2/8] iov_iter: Add a function to extract a page list from an iterator
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On 1/24/23 09:01, David Howells wrote:
...
> +/*
> + * Extract a list of contiguous pages from an ITER_BVEC iterator. This does
> + * not get references on the pages, nor does it get a pin on them.
> + */
> +static ssize_t iov_iter_extract_bvec_pages(struct iov_iter *i,
> + struct page ***pages, size_t maxsize,
> + unsigned int maxpages,
> + unsigned int extraction_flags,
> + size_t *offset0)
> +{
> + struct page **p, *page;
> + size_t skip = i->iov_offset, offset;
> + int k;
> +
> + for (;;) {
> + if (i->nr_segs == 0)
> + return 0;
> + maxsize = min(maxsize, i->bvec->bv_len - skip);
> + if (maxsize)
> + break;
> + i->iov_offset = 0;
> + i->nr_segs--;
> + i->kvec++;
> + skip = 0;
> + }
> +
> + skip += i->bvec->bv_offset;
> + page = i->bvec->bv_page + skip / PAGE_SIZE;
> + offset = skip % PAGE_SIZE;
> + *offset0 = offset;
> +
> + maxpages = want_pages_array(pages, maxsize, offset, maxpages);
> + if (!maxpages)
> + return -ENOMEM;

Is it OK that the iov_iter position has been advanced, and left that way,
in the case of an early -ENOMEM return here?


thanks,
--
John Hubbard
NVIDIA

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