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d72dc8a25a
Make pagevec_lookup() (and underlying find_get_pages()) update index to the next page where iteration should continue. Most callers want this and also pagevec_lookup_tag() already does this. Link: http://lkml.kernel.org/r/20170726114704.7626-3-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
269 lines
6.8 KiB
C
269 lines
6.8 KiB
C
/* file-nommu.c: no-MMU version of ramfs
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*
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* Copyright (C) 2005 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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/init.h>
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#include <linux/string.h>
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#include <linux/backing-dev.h>
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#include <linux/ramfs.h>
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#include <linux/pagevec.h>
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#include <linux/mman.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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static int ramfs_nommu_setattr(struct dentry *, struct iattr *);
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static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
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unsigned long addr,
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unsigned long len,
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unsigned long pgoff,
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unsigned long flags);
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static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma);
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static unsigned ramfs_mmap_capabilities(struct file *file)
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{
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return NOMMU_MAP_DIRECT | NOMMU_MAP_COPY | NOMMU_MAP_READ |
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NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
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}
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const struct file_operations ramfs_file_operations = {
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.mmap_capabilities = ramfs_mmap_capabilities,
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.mmap = ramfs_nommu_mmap,
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.get_unmapped_area = ramfs_nommu_get_unmapped_area,
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.read_iter = generic_file_read_iter,
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.write_iter = generic_file_write_iter,
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.fsync = noop_fsync,
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.splice_read = generic_file_splice_read,
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.splice_write = iter_file_splice_write,
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.llseek = generic_file_llseek,
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};
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const struct inode_operations ramfs_file_inode_operations = {
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.setattr = ramfs_nommu_setattr,
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.getattr = simple_getattr,
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};
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/*****************************************************************************/
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/*
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* add a contiguous set of pages into a ramfs inode when it's truncated from
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* size 0 on the assumption that it's going to be used for an mmap of shared
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* memory
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*/
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int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
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{
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unsigned long npages, xpages, loop;
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struct page *pages;
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unsigned order;
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void *data;
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int ret;
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gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
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/* make various checks */
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order = get_order(newsize);
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if (unlikely(order >= MAX_ORDER))
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return -EFBIG;
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ret = inode_newsize_ok(inode, newsize);
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if (ret)
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return ret;
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i_size_write(inode, newsize);
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/* allocate enough contiguous pages to be able to satisfy the
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* request */
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pages = alloc_pages(gfp, order);
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if (!pages)
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return -ENOMEM;
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/* split the high-order page into an array of single pages */
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xpages = 1UL << order;
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npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
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split_page(pages, order);
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/* trim off any pages we don't actually require */
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for (loop = npages; loop < xpages; loop++)
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__free_page(pages + loop);
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/* clear the memory we allocated */
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newsize = PAGE_SIZE * npages;
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data = page_address(pages);
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memset(data, 0, newsize);
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/* attach all the pages to the inode's address space */
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for (loop = 0; loop < npages; loop++) {
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struct page *page = pages + loop;
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ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
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gfp);
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if (ret < 0)
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goto add_error;
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/* prevent the page from being discarded on memory pressure */
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SetPageDirty(page);
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SetPageUptodate(page);
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unlock_page(page);
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put_page(page);
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}
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return 0;
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add_error:
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while (loop < npages)
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__free_page(pages + loop++);
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return ret;
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}
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/*****************************************************************************/
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/*
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*
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*/
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static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
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{
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int ret;
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/* assume a truncate from zero size is going to be for the purposes of
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* shared mmap */
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if (size == 0) {
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if (unlikely(newsize >> 32))
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return -EFBIG;
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return ramfs_nommu_expand_for_mapping(inode, newsize);
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}
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/* check that a decrease in size doesn't cut off any shared mappings */
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if (newsize < size) {
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ret = nommu_shrink_inode_mappings(inode, size, newsize);
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if (ret < 0)
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return ret;
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}
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truncate_setsize(inode, newsize);
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return 0;
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}
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/*****************************************************************************/
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/*
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* handle a change of attributes
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* - we're specifically interested in a change of size
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*/
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static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia)
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{
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struct inode *inode = d_inode(dentry);
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unsigned int old_ia_valid = ia->ia_valid;
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int ret = 0;
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/* POSIX UID/GID verification for setting inode attributes */
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ret = setattr_prepare(dentry, ia);
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if (ret)
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return ret;
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/* pick out size-changing events */
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if (ia->ia_valid & ATTR_SIZE) {
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loff_t size = inode->i_size;
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if (ia->ia_size != size) {
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ret = ramfs_nommu_resize(inode, ia->ia_size, size);
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if (ret < 0 || ia->ia_valid == ATTR_SIZE)
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goto out;
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} else {
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/* we skipped the truncate but must still update
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* timestamps
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*/
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ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
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}
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}
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setattr_copy(inode, ia);
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out:
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ia->ia_valid = old_ia_valid;
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return ret;
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}
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/*****************************************************************************/
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/*
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* try to determine where a shared mapping can be made
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* - we require that:
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* - the pages to be mapped must exist
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* - the pages be physically contiguous in sequence
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*/
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static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
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unsigned long addr, unsigned long len,
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unsigned long pgoff, unsigned long flags)
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{
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unsigned long maxpages, lpages, nr, loop, ret;
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struct inode *inode = file_inode(file);
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struct page **pages = NULL, **ptr, *page;
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loff_t isize;
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/* the mapping mustn't extend beyond the EOF */
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lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
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isize = i_size_read(inode);
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ret = -ENOSYS;
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maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (pgoff >= maxpages)
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goto out;
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if (maxpages - pgoff < lpages)
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goto out;
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/* gang-find the pages */
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pages = kcalloc(lpages, sizeof(struct page *), GFP_KERNEL);
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if (!pages)
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goto out_free;
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nr = find_get_pages(inode->i_mapping, &pgoff, lpages, pages);
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if (nr != lpages)
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goto out_free_pages; /* leave if some pages were missing */
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/* check the pages for physical adjacency */
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ptr = pages;
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page = *ptr++;
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page++;
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for (loop = lpages; loop > 1; loop--)
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if (*ptr++ != page++)
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goto out_free_pages;
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/* okay - all conditions fulfilled */
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ret = (unsigned long) page_address(pages[0]);
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out_free_pages:
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ptr = pages;
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for (loop = nr; loop > 0; loop--)
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put_page(*ptr++);
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out_free:
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kfree(pages);
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out:
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return ret;
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}
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/*****************************************************************************/
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/*
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* set up a mapping for shared memory segments
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*/
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static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
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{
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if (!(vma->vm_flags & (VM_SHARED | VM_MAYSHARE)))
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return -ENOSYS;
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file_accessed(file);
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vma->vm_ops = &generic_file_vm_ops;
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return 0;
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}
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