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![Cong Wang](/assets/img/avatar_default.png)
Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Cong Wang <amwang@redhat.com>
243 lines
6.4 KiB
C
243 lines
6.4 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/percpu.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/proc_fs.h>
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#include <linux/export.h>
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#include "rds.h"
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/*
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* This file implements a getsockopt() call which copies a set of fixed
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* sized structs into a user-specified buffer as a means of providing
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* read-only information about RDS.
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*
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* For a given information source there are a given number of fixed sized
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* structs at a given time. The structs are only copied if the user-specified
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* buffer is big enough. The destination pages that make up the buffer
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* are pinned for the duration of the copy.
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*
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* This gives us the following benefits:
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*
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* - simple implementation, no copy "position" across multiple calls
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* - consistent snapshot of an info source
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* - atomic copy works well with whatever locking info source has
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* - one portable tool to get rds info across implementations
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* - long-lived tool can get info without allocating
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*
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* at the following costs:
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*
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* - info source copy must be pinned, may be "large"
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*/
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struct rds_info_iterator {
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struct page **pages;
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void *addr;
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unsigned long offset;
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};
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static DEFINE_SPINLOCK(rds_info_lock);
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static rds_info_func rds_info_funcs[RDS_INFO_LAST - RDS_INFO_FIRST + 1];
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void rds_info_register_func(int optname, rds_info_func func)
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{
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int offset = optname - RDS_INFO_FIRST;
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BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST);
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spin_lock(&rds_info_lock);
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BUG_ON(rds_info_funcs[offset]);
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rds_info_funcs[offset] = func;
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spin_unlock(&rds_info_lock);
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}
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EXPORT_SYMBOL_GPL(rds_info_register_func);
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void rds_info_deregister_func(int optname, rds_info_func func)
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{
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int offset = optname - RDS_INFO_FIRST;
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BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST);
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spin_lock(&rds_info_lock);
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BUG_ON(rds_info_funcs[offset] != func);
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rds_info_funcs[offset] = NULL;
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spin_unlock(&rds_info_lock);
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}
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EXPORT_SYMBOL_GPL(rds_info_deregister_func);
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/*
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* Typically we hold an atomic kmap across multiple rds_info_copy() calls
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* because the kmap is so expensive. This must be called before using blocking
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* operations while holding the mapping and as the iterator is torn down.
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*/
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void rds_info_iter_unmap(struct rds_info_iterator *iter)
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{
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if (iter->addr) {
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kunmap_atomic(iter->addr);
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iter->addr = NULL;
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}
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}
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/*
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* get_user_pages() called flush_dcache_page() on the pages for us.
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*/
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void rds_info_copy(struct rds_info_iterator *iter, void *data,
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unsigned long bytes)
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{
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unsigned long this;
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while (bytes) {
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if (!iter->addr)
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iter->addr = kmap_atomic(*iter->pages);
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this = min(bytes, PAGE_SIZE - iter->offset);
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rdsdebug("page %p addr %p offset %lu this %lu data %p "
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"bytes %lu\n", *iter->pages, iter->addr,
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iter->offset, this, data, bytes);
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memcpy(iter->addr + iter->offset, data, this);
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data += this;
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bytes -= this;
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iter->offset += this;
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if (iter->offset == PAGE_SIZE) {
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kunmap_atomic(iter->addr);
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iter->addr = NULL;
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iter->offset = 0;
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iter->pages++;
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}
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}
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}
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EXPORT_SYMBOL_GPL(rds_info_copy);
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/*
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* @optval points to the userspace buffer that the information snapshot
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* will be copied into.
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*
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* @optlen on input is the size of the buffer in userspace. @optlen
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* on output is the size of the requested snapshot in bytes.
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*
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* This function returns -errno if there is a failure, particularly -ENOSPC
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* if the given userspace buffer was not large enough to fit the snapshot.
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* On success it returns the positive number of bytes of each array element
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* in the snapshot.
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*/
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int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval,
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int __user *optlen)
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{
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struct rds_info_iterator iter;
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struct rds_info_lengths lens;
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unsigned long nr_pages = 0;
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unsigned long start;
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unsigned long i;
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rds_info_func func;
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struct page **pages = NULL;
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int ret;
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int len;
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int total;
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if (get_user(len, optlen)) {
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ret = -EFAULT;
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goto out;
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}
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/* check for all kinds of wrapping and the like */
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start = (unsigned long)optval;
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if (len < 0 || len + PAGE_SIZE - 1 < len || start + len < start) {
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ret = -EINVAL;
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goto out;
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}
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/* a 0 len call is just trying to probe its length */
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if (len == 0)
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goto call_func;
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nr_pages = (PAGE_ALIGN(start + len) - (start & PAGE_MASK))
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>> PAGE_SHIFT;
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pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
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if (!pages) {
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ret = -ENOMEM;
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goto out;
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}
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ret = get_user_pages_fast(start, nr_pages, 1, pages);
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if (ret != nr_pages) {
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if (ret > 0)
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nr_pages = ret;
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else
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nr_pages = 0;
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ret = -EAGAIN; /* XXX ? */
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goto out;
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}
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rdsdebug("len %d nr_pages %lu\n", len, nr_pages);
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call_func:
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func = rds_info_funcs[optname - RDS_INFO_FIRST];
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if (!func) {
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ret = -ENOPROTOOPT;
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goto out;
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}
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iter.pages = pages;
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iter.addr = NULL;
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iter.offset = start & (PAGE_SIZE - 1);
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func(sock, len, &iter, &lens);
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BUG_ON(lens.each == 0);
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total = lens.nr * lens.each;
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rds_info_iter_unmap(&iter);
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if (total > len) {
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len = total;
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ret = -ENOSPC;
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} else {
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len = total;
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ret = lens.each;
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}
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if (put_user(len, optlen))
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ret = -EFAULT;
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out:
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for (i = 0; pages && i < nr_pages; i++)
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put_page(pages[i]);
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kfree(pages);
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return ret;
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}
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