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v6.8
  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* file-nommu.c: no-MMU version of ramfs
  3 *
  4 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
  5 * Written by David Howells (dhowells@redhat.com)
 
 
 
 
 
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/fs.h>
 10#include <linux/mm.h>
 11#include <linux/pagemap.h>
 12#include <linux/highmem.h>
 13#include <linux/init.h>
 14#include <linux/string.h>
 15#include <linux/backing-dev.h>
 16#include <linux/ramfs.h>
 17#include <linux/pagevec.h>
 18#include <linux/mman.h>
 19#include <linux/sched.h>
 20#include <linux/slab.h>
 21
 22#include <linux/uaccess.h>
 23#include "internal.h"
 24
 25static int ramfs_nommu_setattr(struct mnt_idmap *, struct dentry *, struct iattr *);
 26static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
 27						   unsigned long addr,
 28						   unsigned long len,
 29						   unsigned long pgoff,
 30						   unsigned long flags);
 31static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma);
 32
 33static unsigned ramfs_mmap_capabilities(struct file *file)
 34{
 35	return NOMMU_MAP_DIRECT | NOMMU_MAP_COPY | NOMMU_MAP_READ |
 36		NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
 37}
 
 38
 39const struct file_operations ramfs_file_operations = {
 40	.mmap_capabilities	= ramfs_mmap_capabilities,
 41	.mmap			= ramfs_nommu_mmap,
 42	.get_unmapped_area	= ramfs_nommu_get_unmapped_area,
 43	.read_iter		= generic_file_read_iter,
 44	.write_iter		= generic_file_write_iter,
 
 
 45	.fsync			= noop_fsync,
 46	.splice_read		= filemap_splice_read,
 47	.splice_write		= iter_file_splice_write,
 48	.llseek			= generic_file_llseek,
 49};
 50
 51const struct inode_operations ramfs_file_inode_operations = {
 52	.setattr		= ramfs_nommu_setattr,
 53	.getattr		= simple_getattr,
 54};
 55
 56/*****************************************************************************/
 57/*
 58 * add a contiguous set of pages into a ramfs inode when it's truncated from
 59 * size 0 on the assumption that it's going to be used for an mmap of shared
 60 * memory
 61 */
 62int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
 63{
 64	unsigned long npages, xpages, loop;
 65	struct page *pages;
 66	unsigned order;
 67	void *data;
 68	int ret;
 69	gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
 70
 71	/* make various checks */
 72	order = get_order(newsize);
 73	if (unlikely(order > MAX_PAGE_ORDER))
 74		return -EFBIG;
 75
 76	ret = inode_newsize_ok(inode, newsize);
 77	if (ret)
 78		return ret;
 79
 80	i_size_write(inode, newsize);
 81
 82	/* allocate enough contiguous pages to be able to satisfy the
 83	 * request */
 84	pages = alloc_pages(gfp, order);
 85	if (!pages)
 86		return -ENOMEM;
 87
 88	/* split the high-order page into an array of single pages */
 89	xpages = 1UL << order;
 90	npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
 91
 92	split_page(pages, order);
 93
 94	/* trim off any pages we don't actually require */
 95	for (loop = npages; loop < xpages; loop++)
 96		__free_page(pages + loop);
 97
 98	/* clear the memory we allocated */
 99	newsize = PAGE_SIZE * npages;
100	data = page_address(pages);
101	memset(data, 0, newsize);
102
103	/* attach all the pages to the inode's address space */
104	for (loop = 0; loop < npages; loop++) {
105		struct page *page = pages + loop;
106
107		ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
108					gfp);
109		if (ret < 0)
110			goto add_error;
111
112		/* prevent the page from being discarded on memory pressure */
113		SetPageDirty(page);
114		SetPageUptodate(page);
115
116		unlock_page(page);
117		put_page(page);
118	}
119
120	return 0;
121
122add_error:
123	while (loop < npages)
124		__free_page(pages + loop++);
125	return ret;
126}
127
128/*****************************************************************************/
129/*
130 *
131 */
132static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
133{
134	int ret;
135
136	/* assume a truncate from zero size is going to be for the purposes of
137	 * shared mmap */
138	if (size == 0) {
139		if (unlikely(newsize >> 32))
140			return -EFBIG;
141
142		return ramfs_nommu_expand_for_mapping(inode, newsize);
143	}
144
145	/* check that a decrease in size doesn't cut off any shared mappings */
146	if (newsize < size) {
147		ret = nommu_shrink_inode_mappings(inode, size, newsize);
148		if (ret < 0)
149			return ret;
150	}
151
152	truncate_setsize(inode, newsize);
153	return 0;
154}
155
156/*****************************************************************************/
157/*
158 * handle a change of attributes
159 * - we're specifically interested in a change of size
160 */
161static int ramfs_nommu_setattr(struct mnt_idmap *idmap,
162			       struct dentry *dentry, struct iattr *ia)
163{
164	struct inode *inode = d_inode(dentry);
165	unsigned int old_ia_valid = ia->ia_valid;
166	int ret = 0;
167
168	/* POSIX UID/GID verification for setting inode attributes */
169	ret = setattr_prepare(&nop_mnt_idmap, dentry, ia);
170	if (ret)
171		return ret;
172
173	/* pick out size-changing events */
174	if (ia->ia_valid & ATTR_SIZE) {
175		loff_t size = inode->i_size;
176
177		if (ia->ia_size != size) {
178			ret = ramfs_nommu_resize(inode, ia->ia_size, size);
179			if (ret < 0 || ia->ia_valid == ATTR_SIZE)
180				goto out;
181		} else {
182			/* we skipped the truncate but must still update
183			 * timestamps
184			 */
185			ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
186		}
187	}
188
189	setattr_copy(&nop_mnt_idmap, inode, ia);
190 out:
191	ia->ia_valid = old_ia_valid;
192	return ret;
193}
194
195/*****************************************************************************/
196/*
197 * try to determine where a shared mapping can be made
198 * - we require that:
199 *   - the pages to be mapped must exist
200 *   - the pages be physically contiguous in sequence
201 */
202static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
203					    unsigned long addr, unsigned long len,
204					    unsigned long pgoff, unsigned long flags)
205{
206	unsigned long maxpages, lpages, nr_folios, loop, ret, nr_pages, pfn;
207	struct inode *inode = file_inode(file);
208	struct folio_batch fbatch;
209	loff_t isize;
210
 
 
 
211	/* the mapping mustn't extend beyond the EOF */
212	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
213	isize = i_size_read(inode);
214
215	ret = -ENOSYS;
216	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
217	if (pgoff >= maxpages)
218		goto out;
219
220	if (maxpages - pgoff < lpages)
221		goto out;
222
223	/* gang-find the pages */
224	folio_batch_init(&fbatch);
225	nr_pages = 0;
226repeat:
227	nr_folios = filemap_get_folios_contig(inode->i_mapping, &pgoff,
228			ULONG_MAX, &fbatch);
229	if (!nr_folios) {
230		ret = -ENOSYS;
231		return ret;
232	}
233
234	if (ret == -ENOSYS) {
235		ret = (unsigned long) folio_address(fbatch.folios[0]);
236		pfn = folio_pfn(fbatch.folios[0]);
237	}
238	/* check the pages for physical adjacency */
239	for (loop = 0; loop < nr_folios; loop++) {
240		if (pfn + nr_pages != folio_pfn(fbatch.folios[loop])) {
241			ret = -ENOSYS;
242			goto out_free; /* leave if not physical adjacent */
243		}
244		nr_pages += folio_nr_pages(fbatch.folios[loop]);
245		if (nr_pages >= lpages)
246			goto out_free; /* successfully found desired pages*/
247	}
248
249	if (nr_pages < lpages) {
250		folio_batch_release(&fbatch);
251		goto repeat; /* loop if pages are missing */
252	}
253	/* okay - all conditions fulfilled */
 
254
 
 
 
 
255out_free:
256	folio_batch_release(&fbatch);
257out:
258	return ret;
259}
260
261/*****************************************************************************/
262/*
263 * set up a mapping for shared memory segments
264 */
265static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
266{
267	if (!is_nommu_shared_mapping(vma->vm_flags))
268		return -ENOSYS;
269
270	file_accessed(file);
271	vma->vm_ops = &generic_file_vm_ops;
272	return 0;
273}
v3.5.6
 
  1/* file-nommu.c: no-MMU version of ramfs
  2 *
  3 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
  4 * Written by David Howells (dhowells@redhat.com)
  5 *
  6 * This program is free software; you can redistribute it and/or
  7 * modify it under the terms of the GNU General Public License
  8 * as published by the Free Software Foundation; either version
  9 * 2 of the License, or (at your option) any later version.
 10 */
 11
 12#include <linux/module.h>
 13#include <linux/fs.h>
 14#include <linux/mm.h>
 15#include <linux/pagemap.h>
 16#include <linux/highmem.h>
 17#include <linux/init.h>
 18#include <linux/string.h>
 19#include <linux/backing-dev.h>
 20#include <linux/ramfs.h>
 21#include <linux/pagevec.h>
 22#include <linux/mman.h>
 23#include <linux/sched.h>
 24#include <linux/slab.h>
 25
 26#include <asm/uaccess.h>
 27#include "internal.h"
 28
 29static int ramfs_nommu_setattr(struct dentry *, struct iattr *);
 
 
 
 
 
 
 30
 31const struct address_space_operations ramfs_aops = {
 32	.readpage		= simple_readpage,
 33	.write_begin		= simple_write_begin,
 34	.write_end		= simple_write_end,
 35	.set_page_dirty		= __set_page_dirty_no_writeback,
 36};
 37
 38const struct file_operations ramfs_file_operations = {
 
 39	.mmap			= ramfs_nommu_mmap,
 40	.get_unmapped_area	= ramfs_nommu_get_unmapped_area,
 41	.read			= do_sync_read,
 42	.aio_read		= generic_file_aio_read,
 43	.write			= do_sync_write,
 44	.aio_write		= generic_file_aio_write,
 45	.fsync			= noop_fsync,
 46	.splice_read		= generic_file_splice_read,
 47	.splice_write		= generic_file_splice_write,
 48	.llseek			= generic_file_llseek,
 49};
 50
 51const struct inode_operations ramfs_file_inode_operations = {
 52	.setattr		= ramfs_nommu_setattr,
 53	.getattr		= simple_getattr,
 54};
 55
 56/*****************************************************************************/
 57/*
 58 * add a contiguous set of pages into a ramfs inode when it's truncated from
 59 * size 0 on the assumption that it's going to be used for an mmap of shared
 60 * memory
 61 */
 62int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
 63{
 64	unsigned long npages, xpages, loop;
 65	struct page *pages;
 66	unsigned order;
 67	void *data;
 68	int ret;
 
 69
 70	/* make various checks */
 71	order = get_order(newsize);
 72	if (unlikely(order >= MAX_ORDER))
 73		return -EFBIG;
 74
 75	ret = inode_newsize_ok(inode, newsize);
 76	if (ret)
 77		return ret;
 78
 79	i_size_write(inode, newsize);
 80
 81	/* allocate enough contiguous pages to be able to satisfy the
 82	 * request */
 83	pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order);
 84	if (!pages)
 85		return -ENOMEM;
 86
 87	/* split the high-order page into an array of single pages */
 88	xpages = 1UL << order;
 89	npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
 90
 91	split_page(pages, order);
 92
 93	/* trim off any pages we don't actually require */
 94	for (loop = npages; loop < xpages; loop++)
 95		__free_page(pages + loop);
 96
 97	/* clear the memory we allocated */
 98	newsize = PAGE_SIZE * npages;
 99	data = page_address(pages);
100	memset(data, 0, newsize);
101
102	/* attach all the pages to the inode's address space */
103	for (loop = 0; loop < npages; loop++) {
104		struct page *page = pages + loop;
105
106		ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
107					GFP_KERNEL);
108		if (ret < 0)
109			goto add_error;
110
111		/* prevent the page from being discarded on memory pressure */
112		SetPageDirty(page);
113		SetPageUptodate(page);
114
115		unlock_page(page);
116		put_page(page);
117	}
118
119	return 0;
120
121add_error:
122	while (loop < npages)
123		__free_page(pages + loop++);
124	return ret;
125}
126
127/*****************************************************************************/
128/*
129 *
130 */
131static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
132{
133	int ret;
134
135	/* assume a truncate from zero size is going to be for the purposes of
136	 * shared mmap */
137	if (size == 0) {
138		if (unlikely(newsize >> 32))
139			return -EFBIG;
140
141		return ramfs_nommu_expand_for_mapping(inode, newsize);
142	}
143
144	/* check that a decrease in size doesn't cut off any shared mappings */
145	if (newsize < size) {
146		ret = nommu_shrink_inode_mappings(inode, size, newsize);
147		if (ret < 0)
148			return ret;
149	}
150
151	truncate_setsize(inode, newsize);
152	return 0;
153}
154
155/*****************************************************************************/
156/*
157 * handle a change of attributes
158 * - we're specifically interested in a change of size
159 */
160static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia)
 
161{
162	struct inode *inode = dentry->d_inode;
163	unsigned int old_ia_valid = ia->ia_valid;
164	int ret = 0;
165
166	/* POSIX UID/GID verification for setting inode attributes */
167	ret = inode_change_ok(inode, ia);
168	if (ret)
169		return ret;
170
171	/* pick out size-changing events */
172	if (ia->ia_valid & ATTR_SIZE) {
173		loff_t size = inode->i_size;
174
175		if (ia->ia_size != size) {
176			ret = ramfs_nommu_resize(inode, ia->ia_size, size);
177			if (ret < 0 || ia->ia_valid == ATTR_SIZE)
178				goto out;
179		} else {
180			/* we skipped the truncate but must still update
181			 * timestamps
182			 */
183			ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
184		}
185	}
186
187	setattr_copy(inode, ia);
188 out:
189	ia->ia_valid = old_ia_valid;
190	return ret;
191}
192
193/*****************************************************************************/
194/*
195 * try to determine where a shared mapping can be made
196 * - we require that:
197 *   - the pages to be mapped must exist
198 *   - the pages be physically contiguous in sequence
199 */
200unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
201					    unsigned long addr, unsigned long len,
202					    unsigned long pgoff, unsigned long flags)
203{
204	unsigned long maxpages, lpages, nr, loop, ret;
205	struct inode *inode = file->f_path.dentry->d_inode;
206	struct page **pages = NULL, **ptr, *page;
207	loff_t isize;
208
209	if (!(flags & MAP_SHARED))
210		return addr;
211
212	/* the mapping mustn't extend beyond the EOF */
213	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
214	isize = i_size_read(inode);
215
216	ret = -EINVAL;
217	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
218	if (pgoff >= maxpages)
219		goto out;
220
221	if (maxpages - pgoff < lpages)
222		goto out;
223
224	/* gang-find the pages */
225	ret = -ENOMEM;
226	pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
227	if (!pages)
228		goto out_free;
229
230	nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
231	if (nr != lpages)
232		goto out_free_pages; /* leave if some pages were missing */
 
233
 
 
 
 
234	/* check the pages for physical adjacency */
235	ptr = pages;
236	page = *ptr++;
237	page++;
238	for (loop = lpages; loop > 1; loop--)
239		if (*ptr++ != page++)
240			goto out_free_pages;
 
 
 
241
 
 
 
 
242	/* okay - all conditions fulfilled */
243	ret = (unsigned long) page_address(pages[0]);
244
245out_free_pages:
246	ptr = pages;
247	for (loop = nr; loop > 0; loop--)
248		put_page(*ptr++);
249out_free:
250	kfree(pages);
251out:
252	return ret;
253}
254
255/*****************************************************************************/
256/*
257 * set up a mapping for shared memory segments
258 */
259int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
260{
261	if (!(vma->vm_flags & VM_SHARED))
262		return -ENOSYS;
263
264	file_accessed(file);
265	vma->vm_ops = &generic_file_vm_ops;
266	return 0;
267}