[linux.git] / fs / ramfs / file-nommu.c

/* file-nommu.c: no-MMU version of ramfs
 *
 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
#include <linux/backing-dev.h>
#include <linux/ramfs.h>
#include <linux/quotaops.h>
#include <linux/pagevec.h>
#include <linux/mman.h>

#include <asm/uaccess.h>
#include "internal.h"

static int ramfs_nommu_setattr(struct dentry *, struct iattr *);

struct address_space_operations ramfs_aops = {
	.readpage		= simple_readpage,
	.prepare_write		= simple_prepare_write,
	.commit_write		= simple_commit_write
};

const struct file_operations ramfs_file_operations = {
	.mmap			= ramfs_nommu_mmap,
	.get_unmapped_area	= ramfs_nommu_get_unmapped_area,
	.read			= generic_file_read,
	.write			= generic_file_write,
	.fsync			= simple_sync_file,
	.sendfile		= generic_file_sendfile,
	.llseek			= generic_file_llseek,
};

struct inode_operations ramfs_file_inode_operations = {
	.setattr		= ramfs_nommu_setattr,
	.getattr		= simple_getattr,
};

/*****************************************************************************/
/*
 * add a contiguous set of pages into a ramfs inode when it's truncated from
 * size 0 on the assumption that it's going to be used for an mmap of shared
 * memory
 */
static int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
{
	struct pagevec lru_pvec;
	unsigned long npages, xpages, loop, limit;
	struct page *pages;
	unsigned order;
	void *data;
	int ret;

	/* make various checks */
	order = get_order(newsize);
	if (unlikely(order >= MAX_ORDER))
		goto too_big;

	limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
	if (limit != RLIM_INFINITY && newsize > limit)
		goto fsize_exceeded;

	if (newsize > inode->i_sb->s_maxbytes)
		goto too_big;

	i_size_write(inode, newsize);

	/* allocate enough contiguous pages to be able to satisfy the
	 * request */
	pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order);
	if (!pages)
		return -ENOMEM;

	/* split the high-order page into an array of single pages */
	xpages = 1UL << order;
	npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;

	split_page(pages, order);

	/* trim off any pages we don't actually require */
	for (loop = npages; loop < xpages; loop++)
		__free_page(pages + loop);

	/* clear the memory we allocated */
	newsize = PAGE_SIZE * npages;
	data = page_address(pages);
	memset(data, 0, newsize);

	/* attach all the pages to the inode's address space */
	pagevec_init(&lru_pvec, 0);
	for (loop = 0; loop < npages; loop++) {
		struct page *page = pages + loop;

		ret = add_to_page_cache(page, inode->i_mapping, loop, GFP_KERNEL);
		if (ret < 0)
			goto add_error;

		if (!pagevec_add(&lru_pvec, page))
			__pagevec_lru_add(&lru_pvec);

		unlock_page(page);
	}

	pagevec_lru_add(&lru_pvec);
	return 0;

 fsize_exceeded:
	send_sig(SIGXFSZ, current, 0);
 too_big:
	return -EFBIG;

 add_error:
	page_cache_release(pages + loop);
	for (loop++; loop < npages; loop++)
		__free_page(pages + loop);
	return ret;
}

/*****************************************************************************/
/*
 * check that file shrinkage doesn't leave any VMAs dangling in midair
 */
static int ramfs_nommu_check_mappings(struct inode *inode,
				      size_t newsize, size_t size)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;

	/* search for VMAs that fall within the dead zone */
	vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
			      newsize >> PAGE_SHIFT,
			      (size + PAGE_SIZE - 1) >> PAGE_SHIFT
			      ) {
		/* found one - only interested if it's shared out of the page
		 * cache */
		if (vma->vm_flags & VM_SHARED)
			return -ETXTBSY; /* not quite true, but near enough */
	}

	return 0;
}

/*****************************************************************************/
/*
 *
 */
static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
{
	int ret;

	/* assume a truncate from zero size is going to be for the purposes of
	 * shared mmap */
	if (size == 0) {
		if (unlikely(newsize >> 32))
			return -EFBIG;

		return ramfs_nommu_expand_for_mapping(inode, newsize);
	}

	/* check that a decrease in size doesn't cut off any shared mappings */
	if (newsize < size) {
		ret = ramfs_nommu_check_mappings(inode, newsize, size);
		if (ret < 0)
			return ret;
	}

	ret = vmtruncate(inode, size);

	return ret;
}

/*****************************************************************************/
/*
 * handle a change of attributes
 * - we're specifically interested in a change of size
 */
static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia)
{
	struct inode *inode = dentry->d_inode;
	unsigned int old_ia_valid = ia->ia_valid;
	int ret = 0;

	/* by providing our own setattr() method, we skip this quotaism */
	if ((old_ia_valid & ATTR_UID && ia->ia_uid != inode->i_uid) ||
	    (old_ia_valid & ATTR_GID && ia->ia_gid != inode->i_gid))
		ret = DQUOT_TRANSFER(inode, ia) ? -EDQUOT : 0;

	/* pick out size-changing events */
	if (ia->ia_valid & ATTR_SIZE) {
		loff_t size = i_size_read(inode);
		if (ia->ia_size != size) {
			ret = ramfs_nommu_resize(inode, ia->ia_size, size);
			if (ret < 0 || ia->ia_valid == ATTR_SIZE)
				goto out;
		} else {
			/* we skipped the truncate but must still update
			 * timestamps
			 */
			ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
		}
	}

	ret = inode_setattr(inode, ia);
 out:
	ia->ia_valid = old_ia_valid;
	return ret;
}

/*****************************************************************************/
/*
 * try to determine where a shared mapping can be made
 * - we require that:
 *   - the pages to be mapped must exist
 *   - the pages be physically contiguous in sequence
 */
unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
					    unsigned long addr, unsigned long len,
					    unsigned long pgoff, unsigned long flags)
{
	unsigned long maxpages, lpages, nr, loop, ret;
	struct inode *inode = file->f_dentry->d_inode;
	struct page **pages = NULL, **ptr, *page;
	loff_t isize;

	if (!(flags & MAP_SHARED))
		return addr;

	/* the mapping mustn't extend beyond the EOF */
	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
	isize = i_size_read(inode);

	ret = -EINVAL;
	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
	if (pgoff >= maxpages)
		goto out;

	if (maxpages - pgoff < lpages)
		goto out;

	/* gang-find the pages */
	ret = -ENOMEM;
	pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
	if (!pages)
		goto out;

	nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
	if (nr != lpages)
		goto out; /* leave if some pages were missing */

	/* check the pages for physical adjacency */
	ptr = pages;
	page = *ptr++;
	page++;
	for (loop = lpages; loop > 1; loop--)
		if (*ptr++ != page++)
			goto out;

	/* okay - all conditions fulfilled */
	ret = (unsigned long) page_address(pages[0]);

 out:
	if (pages) {
		ptr = pages;
		for (loop = lpages; loop > 0; loop--)
			put_page(*ptr++);
		kfree(pages);
	}

	return ret;
}

/*****************************************************************************/
/*
 * set up a mapping
 */
int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
{
	return 0;
}
Commit	Line	Data
642fb4d1 DH	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 ([email protected])
	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/pagemap.h>
	15	#include <linux/highmem.h>
	16	#include <linux/init.h>
	17	#include <linux/string.h>
	18	#include <linux/smp_lock.h>
	19	#include <linux/backing-dev.h>
	20	#include <linux/ramfs.h>
	21	#include <linux/quotaops.h>
	22	#include <linux/pagevec.h>
	23	#include <linux/mman.h>
	24
	25	#include <asm/uaccess.h>
	26	#include "internal.h"
	27
	28	static int ramfs_nommu_setattr(struct dentry , struct iattr );
	29
	30	struct address_space_operations ramfs_aops = {
	31	.readpage = simple_readpage,
	32	.prepare_write = simple_prepare_write,
	33	.commit_write = simple_commit_write
	34	};
	35
4b6f5d20	36	const struct file_operations ramfs_file_operations = {
642fb4d1 DH	37	.mmap = ramfs_nommu_mmap,
	38	.get_unmapped_area = ramfs_nommu_get_unmapped_area,
	39	.read = generic_file_read,
	40	.write = generic_file_write,
	41	.fsync = simple_sync_file,
	42	.sendfile = generic_file_sendfile,
	43	.llseek = generic_file_llseek,
	44	};
	45
	46	struct inode_operations ramfs_file_inode_operations = {
	47	.setattr = ramfs_nommu_setattr,
	48	.getattr = simple_getattr,
	49	};
	50
	51	/*****************************************************************************/
	52	/*
	53	* add a contiguous set of pages into a ramfs inode when it's truncated from
	54	* size 0 on the assumption that it's going to be used for an mmap of shared
	55	* memory
	56	*/
	57	static int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
	58	{
	59	struct pagevec lru_pvec;
	60	unsigned long npages, xpages, loop, limit;
	61	struct page *pages;
	62	unsigned order;
	63	void *data;
	64	int ret;
	65
	66	/* make various checks */
	67	order = get_order(newsize);
	68	if (unlikely(order >= MAX_ORDER))
	69	goto too_big;
	70
	71	limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
	72	if (limit != RLIM_INFINITY && newsize > limit)
	73	goto fsize_exceeded;
	74
	75	if (newsize > inode->i_sb->s_maxbytes)
	76	goto too_big;
	77
	78	i_size_write(inode, newsize);
	79
	80	/* allocate enough contiguous pages to be able to satisfy the
	81	* request */
	82	pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order);
	83	if (!pages)
	84	return -ENOMEM;
	85
	86	/* split the high-order page into an array of single pages */
	87	xpages = 1UL << order;
	88	npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
	89
84097518	90	split_page(pages, order);
642fb4d1 DH	91
	92	/* trim off any pages we don't actually require */
	93	for (loop = npages; loop < xpages; loop++)
	94	__free_page(pages + loop);
	95
	96	/* clear the memory we allocated */
	97	newsize = PAGE_SIZE * npages;
	98	data = page_address(pages);
	99	memset(data, 0, newsize);
	100
	101	/* attach all the pages to the inode's address space */
	102	pagevec_init(&lru_pvec, 0);
	103	for (loop = 0; loop < npages; loop++) {
	104	struct page *page = pages + loop;
	105
	106	ret = add_to_page_cache(page, inode->i_mapping, loop, GFP_KERNEL);
	107	if (ret < 0)
	108	goto add_error;
	109
	110	if (!pagevec_add(&lru_pvec, page))
	111	__pagevec_lru_add(&lru_pvec);
	112
	113	unlock_page(page);
	114	}
	115
	116	pagevec_lru_add(&lru_pvec);
	117	return 0;
	118
	119	fsize_exceeded:
	120	send_sig(SIGXFSZ, current, 0);
	121	too_big:
	122	return -EFBIG;
	123
	124	add_error:
	125	page_cache_release(pages + loop);
	126	for (loop++; loop < npages; loop++)
	127	__free_page(pages + loop);
	128	return ret;
	129	}
	130
	131	/*****************************************************************************/
	132	/*
	133	* check that file shrinkage doesn't leave any VMAs dangling in midair
	134	*/
	135	static int ramfs_nommu_check_mappings(struct inode *inode,
	136	size_t newsize, size_t size)
	137	{
	138	struct vm_area_struct *vma;
	139	struct prio_tree_iter iter;
	140
	141	/* search for VMAs that fall within the dead zone */
	142	vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
	143	newsize >> PAGE_SHIFT,
	144	(size + PAGE_SIZE - 1) >> PAGE_SHIFT
	145	) {
	146	/* found one - only interested if it's shared out of the page
	147	* cache */
	148	if (vma->vm_flags & VM_SHARED)
	149	return -ETXTBSY; /* not quite true, but near enough */
	150	}
	151
	152	return 0;
	153	}
	154
155	/*****************************************************************************/
156	/*
157	*
158	*/
159	static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
160	{
161	int ret;
162
163	/* assume a truncate from zero size is going to be for the purposes of
164	* shared mmap */
165	if (size == 0) {
166	if (unlikely(newsize >> 32))
167	return -EFBIG;
168
169	return ramfs_nommu_expand_for_mapping(inode, newsize);
170	}
171
172	/* check that a decrease in size doesn't cut off any shared mappings */
173	if (newsize < size) {
174	ret = ramfs_nommu_check_mappings(inode, newsize, size);
175	if (ret < 0)
176	return ret;
177	}
178
179	ret = vmtruncate(inode, size);
180
181	return ret;
182	}
183
184	/*****************************************************************************/
185	/*
186	* handle a change of attributes
187	* - we're specifically interested in a change of size
188	*/
189	static int ramfs_nommu_setattr(struct dentry dentry, struct iattr ia)
190	{
191	struct inode *inode = dentry->d_inode;
192	unsigned int old_ia_valid = ia->ia_valid;
193	int ret = 0;
194
195	/* by providing our own setattr() method, we skip this quotaism */
196	if ((old_ia_valid & ATTR_UID && ia->ia_uid != inode->i_uid) \|\|
197	(old_ia_valid & ATTR_GID && ia->ia_gid != inode->i_gid))
198	ret = DQUOT_TRANSFER(inode, ia) ? -EDQUOT : 0;
199
200	/* pick out size-changing events */
201	if (ia->ia_valid & ATTR_SIZE) {
202	loff_t size = i_size_read(inode);
203	if (ia->ia_size != size) {
204	ret = ramfs_nommu_resize(inode, ia->ia_size, size);
205	if (ret < 0 \|\| ia->ia_valid == ATTR_SIZE)
206	goto out;
207	} else {
208	/* we skipped the truncate but must still update
209	* timestamps
210	*/
211	ia->ia_valid \|= ATTR_MTIME\|ATTR_CTIME;
212	}
213	}
214
215	ret = inode_setattr(inode, ia);
216	out:
217	ia->ia_valid = old_ia_valid;
218	return ret;
219	}
220
221	/*****************************************************************************/
222	/*
223	* try to determine where a shared mapping can be made
224	* - we require that:
225	* - the pages to be mapped must exist
226	* - the pages be physically contiguous in sequence
227	*/
228	unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
229	unsigned long addr, unsigned long len,
230	unsigned long pgoff, unsigned long flags)
231	{
232	unsigned long maxpages, lpages, nr, loop, ret;
233	struct inode *inode = file->f_dentry->d_inode;
234	struct page pages = NULL, ptr, *page;
235	loff_t isize;
236
237	if (!(flags & MAP_SHARED))
238	return addr;
239
240	/* the mapping mustn't extend beyond the EOF */
241	lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
242	isize = i_size_read(inode);
243
244	ret = -EINVAL;
245	maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
246	if (pgoff >= maxpages)
247	goto out;
248
249	if (maxpages - pgoff < lpages)
250	goto out;
251
252	/* gang-find the pages */
253	ret = -ENOMEM;
254	pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
255	if (!pages)
256	goto out;
257
258	nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
259	if (nr != lpages)
260	goto out; /* leave if some pages were missing */
261
262	/* check the pages for physical adjacency */
263	ptr = pages;
264	page = *ptr++;
265	page++;
266	for (loop = lpages; loop > 1; loop--)
267	if (*ptr++ != page++)
268	goto out;
269
270	/* okay - all conditions fulfilled */
271	ret = (unsigned long) page_address(pages[0]);
272
273	out:
274	if (pages) {
275	ptr = pages;
276	for (loop = lpages; loop > 0; loop--)
277	put_page(*ptr++);
278	kfree(pages);
279	}
280
281	return ret;
282	}
283
284	/*****************************************************************************/
285	/*
286	* set up a mapping
287	*/
288	int ramfs_nommu_mmap(struct file file, struct vm_area_struct vma)
289	{
290	return 0;
291	}