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![Ben Hutchings](/assets/img/avatar_default.png)
Fix incorrect start markers, wrapped summary lines, missing section breaks, incorrect separators, and some name mismatches. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
215 lines
5.8 KiB
C
215 lines
5.8 KiB
C
/*
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* Copyright (c) 2006 Oracle. All rights reserved.
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*
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* This software is available to you under a choice of one of two
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* licenses. You may choose to be licensed under the terms of the GNU
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* General Public License (GPL) Version 2, available from the file
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* COPYING in the main directory of this source tree, or the
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* OpenIB.org BSD license below:
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*
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* Redistribution and use in source and binary forms, with or
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* without modification, are permitted provided that the following
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* conditions are met:
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*
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* - Redistributions of source code must retain the above
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* copyright notice, this list of conditions and the following
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* disclaimer.
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*
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* - Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*/
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#include <linux/highmem.h>
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#include <linux/gfp.h>
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#include <linux/cpu.h>
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#include <linux/export.h>
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#include "rds.h"
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struct rds_page_remainder {
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struct page *r_page;
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unsigned long r_offset;
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};
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder,
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rds_page_remainders);
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/*
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* returns 0 on success or -errno on failure.
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*
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* We don't have to worry about flush_dcache_page() as this only works
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* with private pages. If, say, we were to do directed receive to pinned
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* user pages we'd have to worry more about cache coherence. (Though
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* the flush_dcache_page() in get_user_pages() would probably be enough).
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*/
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int rds_page_copy_user(struct page *page, unsigned long offset,
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void __user *ptr, unsigned long bytes,
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int to_user)
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{
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unsigned long ret;
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void *addr;
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addr = kmap(page);
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if (to_user) {
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rds_stats_add(s_copy_to_user, bytes);
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ret = copy_to_user(ptr, addr + offset, bytes);
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} else {
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rds_stats_add(s_copy_from_user, bytes);
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ret = copy_from_user(addr + offset, ptr, bytes);
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}
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kunmap(page);
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return ret ? -EFAULT : 0;
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}
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EXPORT_SYMBOL_GPL(rds_page_copy_user);
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/**
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* rds_page_remainder_alloc - build up regions of a message.
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*
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* @scat: Scatter list for message
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* @bytes: the number of bytes needed.
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* @gfp: the waiting behaviour of the allocation
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*
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* @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
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* kmap the pages, etc.
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*
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* If @bytes is at least a full page then this just returns a page from
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* alloc_page().
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*
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* If @bytes is a partial page then this stores the unused region of the
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* page in a per-cpu structure. Future partial-page allocations may be
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* satisfied from that cached region. This lets us waste less memory on
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* small allocations with minimal complexity. It works because the transmit
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* path passes read-only page regions down to devices. They hold a page
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* reference until they are done with the region.
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*/
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int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
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gfp_t gfp)
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{
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struct rds_page_remainder *rem;
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unsigned long flags;
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struct page *page;
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int ret;
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gfp |= __GFP_HIGHMEM;
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/* jump straight to allocation if we're trying for a huge page */
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if (bytes >= PAGE_SIZE) {
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page = alloc_page(gfp);
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if (!page) {
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ret = -ENOMEM;
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} else {
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sg_set_page(scat, page, PAGE_SIZE, 0);
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ret = 0;
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}
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goto out;
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}
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rem = &per_cpu(rds_page_remainders, get_cpu());
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local_irq_save(flags);
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while (1) {
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/* avoid a tiny region getting stuck by tossing it */
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if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
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rds_stats_inc(s_page_remainder_miss);
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__free_page(rem->r_page);
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rem->r_page = NULL;
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}
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/* hand out a fragment from the cached page */
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if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
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sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
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get_page(sg_page(scat));
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if (rem->r_offset != 0)
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rds_stats_inc(s_page_remainder_hit);
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rem->r_offset += bytes;
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if (rem->r_offset == PAGE_SIZE) {
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__free_page(rem->r_page);
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rem->r_page = NULL;
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}
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ret = 0;
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break;
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}
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/* alloc if there is nothing for us to use */
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local_irq_restore(flags);
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put_cpu();
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page = alloc_page(gfp);
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rem = &per_cpu(rds_page_remainders, get_cpu());
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local_irq_save(flags);
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if (!page) {
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ret = -ENOMEM;
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break;
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}
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/* did someone race to fill the remainder before us? */
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if (rem->r_page) {
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__free_page(page);
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continue;
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}
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/* otherwise install our page and loop around to alloc */
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rem->r_page = page;
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rem->r_offset = 0;
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}
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local_irq_restore(flags);
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put_cpu();
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out:
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rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
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ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
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ret ? 0 : scat->length);
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return ret;
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}
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EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
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static int rds_page_remainder_cpu_notify(struct notifier_block *self,
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unsigned long action, void *hcpu)
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{
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struct rds_page_remainder *rem;
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long cpu = (long)hcpu;
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rem = &per_cpu(rds_page_remainders, cpu);
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rdsdebug("cpu %ld action 0x%lx\n", cpu, action);
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switch (action) {
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case CPU_DEAD:
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if (rem->r_page)
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__free_page(rem->r_page);
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rem->r_page = NULL;
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break;
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}
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return 0;
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}
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static struct notifier_block rds_page_remainder_nb = {
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.notifier_call = rds_page_remainder_cpu_notify,
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};
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void rds_page_exit(void)
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{
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int i;
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for_each_possible_cpu(i)
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rds_page_remainder_cpu_notify(&rds_page_remainder_nb,
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(unsigned long)CPU_DEAD,
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(void *)(long)i);
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}
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