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f5f82cd187
Move netfs_extract_iter_to_sg() to lib/scatterlist.c as it's going to be used by more than just network filesystems (AF_ALG, for example). Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: Steve French <sfrench@samba.org> cc: Shyam Prasad N <nspmangalore@gmail.com> cc: Rohith Surabattula <rohiths.msft@gmail.com> cc: Jens Axboe <axboe@kernel.dk> cc: Herbert Xu <herbert@gondor.apana.org.au> cc: "David S. Miller" <davem@davemloft.net> cc: Eric Dumazet <edumazet@google.com> cc: Jakub Kicinski <kuba@kernel.org> cc: Paolo Abeni <pabeni@redhat.com> cc: Matthew Wilcox <willy@infradead.org> cc: linux-crypto@vger.kernel.org cc: linux-cachefs@redhat.com cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: netdev@vger.kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
103 lines
2.9 KiB
C
103 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Iterator helpers.
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*
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* Copyright (C) 2022 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/uio.h>
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#include <linux/scatterlist.h>
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#include <linux/netfs.h>
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#include "internal.h"
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/**
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* netfs_extract_user_iter - Extract the pages from a user iterator into a bvec
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* @orig: The original iterator
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* @orig_len: The amount of iterator to copy
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* @new: The iterator to be set up
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* @extraction_flags: Flags to qualify the request
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*
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* Extract the page fragments from the given amount of the source iterator and
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* build up a second iterator that refers to all of those bits. This allows
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* the original iterator to disposed of.
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*
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* @extraction_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA be
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* allowed on the pages extracted.
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*
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* On success, the number of elements in the bvec is returned, the original
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* iterator will have been advanced by the amount extracted.
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*
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* The iov_iter_extract_mode() function should be used to query how cleanup
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* should be performed.
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*/
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ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
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struct iov_iter *new,
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iov_iter_extraction_t extraction_flags)
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{
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struct bio_vec *bv = NULL;
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struct page **pages;
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unsigned int cur_npages;
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unsigned int max_pages;
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unsigned int npages = 0;
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unsigned int i;
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ssize_t ret;
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size_t count = orig_len, offset, len;
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size_t bv_size, pg_size;
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if (WARN_ON_ONCE(!iter_is_ubuf(orig) && !iter_is_iovec(orig)))
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return -EIO;
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max_pages = iov_iter_npages(orig, INT_MAX);
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bv_size = array_size(max_pages, sizeof(*bv));
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bv = kvmalloc(bv_size, GFP_KERNEL);
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if (!bv)
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return -ENOMEM;
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/* Put the page list at the end of the bvec list storage. bvec
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* elements are larger than page pointers, so as long as we work
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* 0->last, we should be fine.
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*/
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pg_size = array_size(max_pages, sizeof(*pages));
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pages = (void *)bv + bv_size - pg_size;
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while (count && npages < max_pages) {
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ret = iov_iter_extract_pages(orig, &pages, count,
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max_pages - npages, extraction_flags,
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&offset);
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if (ret < 0) {
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pr_err("Couldn't get user pages (rc=%zd)\n", ret);
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break;
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}
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if (ret > count) {
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pr_err("get_pages rc=%zd more than %zu\n", ret, count);
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break;
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}
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count -= ret;
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ret += offset;
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cur_npages = DIV_ROUND_UP(ret, PAGE_SIZE);
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if (npages + cur_npages > max_pages) {
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pr_err("Out of bvec array capacity (%u vs %u)\n",
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npages + cur_npages, max_pages);
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break;
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}
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for (i = 0; i < cur_npages; i++) {
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len = ret > PAGE_SIZE ? PAGE_SIZE : ret;
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bvec_set_page(bv + npages + i, *pages++, len - offset, offset);
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ret -= len;
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offset = 0;
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}
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npages += cur_npages;
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}
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iov_iter_bvec(new, orig->data_source, bv, npages, orig_len - count);
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return npages;
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}
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EXPORT_SYMBOL_GPL(netfs_extract_user_iter);
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