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08582d678f
Overlayfs uses backing files with "fake" overlayfs f_path and "real" underlying f_inode, in order to use underlying inode aops for mapped files and to display the overlayfs path in /proc/<pid>/maps. In preparation for storing the overlayfs "fake" path instead of the underlying "real" path in struct backing_file, define a noop helper file_user_path() that returns f_path for now. Use the new helper in procfs and kernel logs whenever a path of a mapped file is displayed to users. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Link: https://lore.kernel.org/r/20231009153712.1566422-3-amir73il@gmail.com Signed-off-by: Christian Brauner <brauner@kernel.org>
116 lines
2.6 KiB
C
116 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* nommu.c: mmu-less memory info files
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*
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* Copyright (C) 2004 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/init.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/mman.h>
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#include <linux/proc_fs.h>
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#include <linux/mm.h>
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#include <linux/mmzone.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/smp.h>
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#include <linux/seq_file.h>
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#include <linux/hugetlb.h>
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#include <linux/vmalloc.h>
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#include <asm/tlb.h>
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#include <asm/div64.h>
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#include "internal.h"
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/*
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* display a single region to a sequenced file
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*/
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static int nommu_region_show(struct seq_file *m, struct vm_region *region)
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{
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unsigned long ino = 0;
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struct file *file;
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dev_t dev = 0;
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int flags;
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flags = region->vm_flags;
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file = region->vm_file;
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if (file) {
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struct inode *inode = file_inode(region->vm_file);
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dev = inode->i_sb->s_dev;
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ino = inode->i_ino;
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}
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seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
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seq_printf(m,
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"%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
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region->vm_start,
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region->vm_end,
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flags & VM_READ ? 'r' : '-',
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flags & VM_WRITE ? 'w' : '-',
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flags & VM_EXEC ? 'x' : '-',
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flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
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((loff_t)region->vm_pgoff) << PAGE_SHIFT,
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MAJOR(dev), MINOR(dev), ino);
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if (file) {
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seq_pad(m, ' ');
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seq_path(m, file_user_path(file), "");
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}
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seq_putc(m, '\n');
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return 0;
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}
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/*
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* display a list of all the REGIONs the kernel knows about
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* - nommu kernels have a single flat list
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*/
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static int nommu_region_list_show(struct seq_file *m, void *_p)
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{
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struct rb_node *p = _p;
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return nommu_region_show(m, rb_entry(p, struct vm_region, vm_rb));
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}
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static void *nommu_region_list_start(struct seq_file *m, loff_t *_pos)
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{
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struct rb_node *p;
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loff_t pos = *_pos;
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down_read(&nommu_region_sem);
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for (p = rb_first(&nommu_region_tree); p; p = rb_next(p))
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if (pos-- == 0)
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return p;
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return NULL;
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}
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static void nommu_region_list_stop(struct seq_file *m, void *v)
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{
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up_read(&nommu_region_sem);
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}
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static void *nommu_region_list_next(struct seq_file *m, void *v, loff_t *pos)
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{
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(*pos)++;
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return rb_next((struct rb_node *) v);
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}
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static const struct seq_operations proc_nommu_region_list_seqop = {
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.start = nommu_region_list_start,
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.next = nommu_region_list_next,
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.stop = nommu_region_list_stop,
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.show = nommu_region_list_show
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};
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static int __init proc_nommu_init(void)
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{
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proc_create_seq("maps", S_IRUGO, NULL, &proc_nommu_region_list_seqop);
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return 0;
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}
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fs_initcall(proc_nommu_init);
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