[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / mm / filemap_xip.c

/*
 *	linux/mm/filemap_xip.c
 *
 * Copyright (C) 2005 IBM Corporation
 * Author: Carsten Otte <cotte@de.ibm.com>
 *
 * derived from linux/mm/filemap.c - Copyright (C) Linus Torvalds
 *
 */

#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/module.h>
#include <linux/uio.h>
#include <linux/rmap.h>
#include <asm/tlbflush.h>
#include "filemap.h"

/*
 * We do use our own empty page to avoid interference with other users
 * of ZERO_PAGE(), such as /dev/zero
 */
static struct page *__xip_sparse_page;

static struct page *xip_sparse_page(void)
{
	if (!__xip_sparse_page) {
		unsigned long zeroes = get_zeroed_page(GFP_HIGHUSER);
		if (zeroes) {
			static DEFINE_SPINLOCK(xip_alloc_lock);
			spin_lock(&xip_alloc_lock);
			if (!__xip_sparse_page)
				__xip_sparse_page = virt_to_page(zeroes);
			else
				free_page(zeroes);
			spin_unlock(&xip_alloc_lock);
		}
	}
	return __xip_sparse_page;
}

/*
 * This is a file read routine for execute in place files, and uses
 * the mapping->a_ops->get_xip_page() function for the actual low-level
 * stuff.
 *
 * Note the struct file* is not used at all.  It may be NULL.
 */
static void
do_xip_mapping_read(struct address_space *mapping,
		    struct file_ra_state *_ra,
		    struct file *filp,
		    loff_t *ppos,
		    read_descriptor_t *desc,
		    read_actor_t actor)
{
	struct inode *inode = mapping->host;
	unsigned long index, end_index, offset;
	loff_t isize;

	BUG_ON(!mapping->a_ops->get_xip_page);

	index = *ppos >> PAGE_CACHE_SHIFT;
	offset = *ppos & ~PAGE_CACHE_MASK;

	isize = i_size_read(inode);
	if (!isize)
		goto out;

	end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
	for (;;) {
		struct page *page;
		unsigned long nr, ret;

		/* nr is the maximum number of bytes to copy from this page */
		nr = PAGE_CACHE_SIZE;
		if (index >= end_index) {
			if (index > end_index)
				goto out;
			nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
			if (nr <= offset) {
				goto out;
			}
		}
		nr = nr - offset;

		page = mapping->a_ops->get_xip_page(mapping,
			index*(PAGE_SIZE/512), 0);
		if (!page)
			goto no_xip_page;
		if (unlikely(IS_ERR(page))) {
			if (PTR_ERR(page) == -ENODATA) {
				/* sparse */
				page = ZERO_PAGE(0);
			} else {
				desc->error = PTR_ERR(page);
				goto out;
			}
		}

		/* If users can be writing to this page using arbitrary
		 * virtual addresses, take care about potential aliasing
		 * before reading the page on the kernel side.
		 */
		if (mapping_writably_mapped(mapping))
			flush_dcache_page(page);

		/*
		 * Ok, we have the page, so now we can copy it to user space...
		 *
		 * The actor routine returns how many bytes were actually used..
		 * NOTE! This may not be the same as how much of a user buffer
		 * we filled up (we may be padding etc), so we can only update
		 * "pos" here (the actor routine has to update the user buffer
		 * pointers and the remaining count).
		 */
		ret = actor(desc, page, offset, nr);
		offset += ret;
		index += offset >> PAGE_CACHE_SHIFT;
		offset &= ~PAGE_CACHE_MASK;

		if (ret == nr && desc->count)
			continue;
		goto out;

no_xip_page:
		/* Did not get the page. Report it */
		desc->error = -EIO;
		goto out;
	}

out:
	*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
	if (filp)
		file_accessed(filp);
}

ssize_t
xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
{
	read_descriptor_t desc;

	if (!access_ok(VERIFY_WRITE, buf, len))
		return -EFAULT;

	desc.written = 0;
	desc.arg.buf = buf;
	desc.count = len;
	desc.error = 0;

	do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
			    ppos, &desc, file_read_actor);

	if (desc.written)
		return desc.written;
	else
		return desc.error;
}
EXPORT_SYMBOL_GPL(xip_file_read);

ssize_t
xip_file_sendfile(struct file *in_file, loff_t *ppos,
	     size_t count, read_actor_t actor, void *target)
{
	read_descriptor_t desc;

	if (!count)
		return 0;

	desc.written = 0;
	desc.count = count;
	desc.arg.data = target;
	desc.error = 0;

	do_xip_mapping_read(in_file->f_mapping, &in_file->f_ra, in_file,
			    ppos, &desc, actor);
	if (desc.written)
		return desc.written;
	return desc.error;
}
EXPORT_SYMBOL_GPL(xip_file_sendfile);

/*
 * __xip_unmap is invoked from xip_unmap and
 * xip_write
 *
 * This function walks all vmas of the address_space and unmaps the
 * __xip_sparse_page when found at pgoff.
 */
static void
__xip_unmap (struct address_space * mapping,
		     unsigned long pgoff)
{
	struct vm_area_struct *vma;
	struct mm_struct *mm;
	struct prio_tree_iter iter;
	unsigned long address;
	pte_t *pte;
	pte_t pteval;
	spinlock_t *ptl;
	struct page *page;

	page = __xip_sparse_page;
	if (!page)
		return;

	spin_lock(&mapping->i_mmap_lock);
	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
		mm = vma->vm_mm;
		address = vma->vm_start +
			((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
		BUG_ON(address < vma->vm_start || address >= vma->vm_end);
		pte = page_check_address(page, mm, address, &ptl);
		if (pte) {
			/* Nuke the page table entry. */
			flush_cache_page(vma, address, pte_pfn(*pte));
			pteval = ptep_clear_flush(vma, address, pte);
			page_remove_rmap(page, vma);
			dec_mm_counter(mm, file_rss);
			BUG_ON(pte_dirty(pteval));
			pte_unmap_unlock(pte, ptl);
			page_cache_release(page);
		}
	}
	spin_unlock(&mapping->i_mmap_lock);
}

/*
 * xip_nopage() is invoked via the vma operations vector for a
 * mapped memory region to read in file data during a page fault.
 *
 * This function is derived from filemap_nopage, but used for execute in place
 */
static struct page *
xip_file_nopage(struct vm_area_struct * area,
		   unsigned long address,
		   int *type)
{
	struct file *file = area->vm_file;
	struct address_space *mapping = file->f_mapping;
	struct inode *inode = mapping->host;
	struct page *page;
	unsigned long size, pgoff, endoff;

	pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT)
		+ area->vm_pgoff;
	endoff = ((area->vm_end - area->vm_start) >> PAGE_CACHE_SHIFT)
		+ area->vm_pgoff;

	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	if (pgoff >= size)
		return NOPAGE_SIGBUS;

	page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0);
	if (!IS_ERR(page))
		goto out;
	if (PTR_ERR(page) != -ENODATA)
		return NOPAGE_SIGBUS;

	/* sparse block */
	if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) &&
	    (area->vm_flags & (VM_SHARED| VM_MAYSHARE)) &&
	    (!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
		/* maybe shared writable, allocate new block */
		page = mapping->a_ops->get_xip_page (mapping,
			pgoff*(PAGE_SIZE/512), 1);
		if (IS_ERR(page))
			return NOPAGE_SIGBUS;
		/* unmap page at pgoff from all other vmas */
		__xip_unmap(mapping, pgoff);
	} else {
		/* not shared and writable, use xip_sparse_page() */
		page = xip_sparse_page();
		if (!page)
			return NOPAGE_OOM;
	}

out:
	page_cache_get(page);
	return page;
}

static struct vm_operations_struct xip_file_vm_ops = {
	.nopage         = xip_file_nopage,
};

int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
{
	BUG_ON(!file->f_mapping->a_ops->get_xip_page);

	file_accessed(file);
	vma->vm_ops = &xip_file_vm_ops;
	return 0;
}
EXPORT_SYMBOL_GPL(xip_file_mmap);

static ssize_t
__xip_file_write(struct file *filp, const char __user *buf,
		  size_t count, loff_t pos, loff_t *ppos)
{
	struct address_space * mapping = filp->f_mapping;
	const struct address_space_operations *a_ops = mapping->a_ops;
	struct inode 	*inode = mapping->host;
	long		status = 0;
	struct page	*page;
	size_t		bytes;
	ssize_t		written = 0;

	BUG_ON(!mapping->a_ops->get_xip_page);

	do {
		unsigned long index;
		unsigned long offset;
		size_t copied;

		offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
		index = pos >> PAGE_CACHE_SHIFT;
		bytes = PAGE_CACHE_SIZE - offset;
		if (bytes > count)
			bytes = count;

		/*
		 * Bring in the user page that we will copy from _first_.
		 * Otherwise there's a nasty deadlock on copying from the
		 * same page as we're writing to, without it being marked
		 * up-to-date.
		 */
		fault_in_pages_readable(buf, bytes);

		page = a_ops->get_xip_page(mapping,
					   index*(PAGE_SIZE/512), 0);
		if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) {
			/* we allocate a new page unmap it */
			page = a_ops->get_xip_page(mapping,
						   index*(PAGE_SIZE/512), 1);
			if (!IS_ERR(page))
				/* unmap page at pgoff from all other vmas */
				__xip_unmap(mapping, index);
		}

		if (IS_ERR(page)) {
			status = PTR_ERR(page);
			break;
		}

		copied = filemap_copy_from_user(page, offset, buf, bytes);
		flush_dcache_page(page);
		if (likely(copied > 0)) {
			status = copied;

			if (status >= 0) {
				written += status;
				count -= status;
				pos += status;
				buf += status;
			}
		}
		if (unlikely(copied != bytes))
			if (status >= 0)
				status = -EFAULT;
		if (status < 0)
			break;
	} while (count);
	*ppos = pos;
	/*
	 * No need to use i_size_read() here, the i_size
	 * cannot change under us because we hold i_mutex.
	 */
	if (pos > inode->i_size) {
		i_size_write(inode, pos);
		mark_inode_dirty(inode);
	}

	return written ? written : status;
}

ssize_t
xip_file_write(struct file *filp, const char __user *buf, size_t len,
	       loff_t *ppos)
{
	struct address_space *mapping = filp->f_mapping;
	struct inode *inode = mapping->host;
	size_t count;
	loff_t pos;
	ssize_t ret;

	mutex_lock(&inode->i_mutex);

	if (!access_ok(VERIFY_READ, buf, len)) {
		ret=-EFAULT;
		goto out_up;
	}

	pos = *ppos;
	count = len;

	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);

	/* We can write back this queue in page reclaim */
	current->backing_dev_info = mapping->backing_dev_info;

	ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode));
	if (ret)
		goto out_backing;
	if (count == 0)
		goto out_backing;

	ret = remove_suid(filp->f_path.dentry);
	if (ret)
		goto out_backing;

	file_update_time(filp);

	ret = __xip_file_write (filp, buf, count, pos, ppos);

 out_backing:
	current->backing_dev_info = NULL;
 out_up:
	mutex_unlock(&inode->i_mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(xip_file_write);

/*
 * truncate a page used for execute in place
 * functionality is analog to block_truncate_page but does use get_xip_page
 * to get the page instead of page cache
 */
int
xip_truncate_page(struct address_space *mapping, loff_t from)
{
	pgoff_t index = from >> PAGE_CACHE_SHIFT;
	unsigned offset = from & (PAGE_CACHE_SIZE-1);
	unsigned blocksize;
	unsigned length;
	struct page *page;

	BUG_ON(!mapping->a_ops->get_xip_page);

	blocksize = 1 << mapping->host->i_blkbits;
	length = offset & (blocksize - 1);

	/* Block boundary? Nothing to do */
	if (!length)
		return 0;

	length = blocksize - length;

	page = mapping->a_ops->get_xip_page(mapping,
					    index*(PAGE_SIZE/512), 0);
	if (!page)
		return -ENOMEM;
	if (unlikely(IS_ERR(page))) {
		if (PTR_ERR(page) == -ENODATA)
			/* Hole? No need to truncate */
			return 0;
		else
			return PTR_ERR(page);
	}
	zero_user_page(page, offset, length, KM_USER0);
	return 0;
}
EXPORT_SYMBOL_GPL(xip_truncate_page);
Commit	Line	Data
ceffc078 CO	1	/*
	2	* linux/mm/filemap_xip.c
	3	*
	4	* Copyright (C) 2005 IBM Corporation
	5	* Author: Carsten Otte <cotte@de.ibm.com>
	6	*
	7	* derived from linux/mm/filemap.c - Copyright (C) Linus Torvalds
	8	*
	9	*/
	10
	11	#include <linux/fs.h>
	12	#include <linux/pagemap.h>
	13	#include <linux/module.h>
	14	#include <linux/uio.h>
	15	#include <linux/rmap.h>
	16	#include <asm/tlbflush.h>
	17	#include "filemap.h"
	18
a76c0b97 CO	19	/*
	20	* We do use our own empty page to avoid interference with other users
	21	* of ZERO_PAGE(), such as /dev/zero
	22	*/
	23	static struct page *__xip_sparse_page;
	24
	25	static struct page *xip_sparse_page(void)
	26	{
	27	if (!__xip_sparse_page) {
	28	unsigned long zeroes = get_zeroed_page(GFP_HIGHUSER);
	29	if (zeroes) {
	30	static DEFINE_SPINLOCK(xip_alloc_lock);
	31	spin_lock(&xip_alloc_lock);
	32	if (!__xip_sparse_page)
	33	__xip_sparse_page = virt_to_page(zeroes);
	34	else
	35	free_page(zeroes);
	36	spin_unlock(&xip_alloc_lock);
	37	}
	38	}
	39	return __xip_sparse_page;
	40	}
	41
ceffc078 CO	42	/*
	43	* This is a file read routine for execute in place files, and uses
	44	* the mapping->a_ops->get_xip_page() function for the actual low-level
	45	* stuff.
	46	*
	47	* Note the struct file* is not used at all. It may be NULL.
	48	*/
	49	static void
	50	do_xip_mapping_read(struct address_space *mapping,
	51	struct file_ra_state *_ra,
	52	struct file *filp,
	53	loff_t *ppos,
	54	read_descriptor_t *desc,
	55	read_actor_t actor)
	56	{
	57	struct inode *inode = mapping->host;
	58	unsigned long index, end_index, offset;
	59	loff_t isize;
	60
	61	BUG_ON(!mapping->a_ops->get_xip_page);
	62
	63	index = *ppos >> PAGE_CACHE_SHIFT;
	64	offset = *ppos & ~PAGE_CACHE_MASK;
	65
	66	isize = i_size_read(inode);
	67	if (!isize)
	68	goto out;
	69
	70	end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
	71	for (;;) {
	72	struct page *page;
	73	unsigned long nr, ret;
	74
	75	/* nr is the maximum number of bytes to copy from this page */
	76	nr = PAGE_CACHE_SIZE;
	77	if (index >= end_index) {
	78	if (index > end_index)
	79	goto out;
	80	nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
	81	if (nr <= offset) {
	82	goto out;
	83	}
	84	}
	85	nr = nr - offset;
	86
	87	page = mapping->a_ops->get_xip_page(mapping,
	88	index*(PAGE_SIZE/512), 0);
	89	if (!page)
	90	goto no_xip_page;
	91	if (unlikely(IS_ERR(page))) {
	92	if (PTR_ERR(page) == -ENODATA) {
	93	/* sparse */
afa597ba	94	page = ZERO_PAGE(0);
ceffc078 CO	95	} else {
	96	desc->error = PTR_ERR(page);
	97	goto out;
	98	}
afa597ba	99	}
ceffc078 CO	100
	101	/* If users can be writing to this page using arbitrary
	102	* virtual addresses, take care about potential aliasing
	103	* before reading the page on the kernel side.
	104	*/
	105	if (mapping_writably_mapped(mapping))
	106	flush_dcache_page(page);
	107
	108	/*
afa597ba	109	* Ok, we have the page, so now we can copy it to user space...
ceffc078 CO	110	*
	111	* The actor routine returns how many bytes were actually used..
	112	* NOTE! This may not be the same as how much of a user buffer
	113	* we filled up (we may be padding etc), so we can only update
	114	* "pos" here (the actor routine has to update the user buffer
	115	* pointers and the remaining count).
	116	*/
	117	ret = actor(desc, page, offset, nr);
	118	offset += ret;
	119	index += offset >> PAGE_CACHE_SHIFT;
	120	offset &= ~PAGE_CACHE_MASK;
	121
	122	if (ret == nr && desc->count)
	123	continue;
	124	goto out;
	125
	126	no_xip_page:
	127	/* Did not get the page. Report it */
	128	desc->error = -EIO;
	129	goto out;
	130	}
	131
	132	out:
	133	*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
	134	if (filp)
	135	file_accessed(filp);
	136	}
	137
ceffc078	138	ssize_t
eb6fe0c3	139	xip_file_read(struct file filp, char __user buf, size_t len, loff_t *ppos)
ceffc078	140	{
eb6fe0c3	141	read_descriptor_t desc;
ceffc078	142
eb6fe0c3 CO	143	if (!access_ok(VERIFY_WRITE, buf, len))
eb6fe0c3 CO	144	return -EFAULT;
ceffc078	145
eb6fe0c3 CO	146	desc.written = 0;
	147	desc.arg.buf = buf;
	148	desc.count = len;
	149	desc.error = 0;
ceffc078	150
eb6fe0c3 CO	151	do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
	152	ppos, &desc, file_read_actor);
	153
	154	if (desc.written)
	155	return desc.written;
	156	else
	157	return desc.error;
ceffc078	158	}
eb6fe0c3	159	EXPORT_SYMBOL_GPL(xip_file_read);
ceffc078 CO	160
	161	ssize_t
	162	xip_file_sendfile(struct file in_file, loff_t ppos,
	163	size_t count, read_actor_t actor, void *target)
	164	{
	165	read_descriptor_t desc;
	166
	167	if (!count)
	168	return 0;
	169
	170	desc.written = 0;
	171	desc.count = count;
	172	desc.arg.data = target;
	173	desc.error = 0;
	174
	175	do_xip_mapping_read(in_file->f_mapping, &in_file->f_ra, in_file,
	176	ppos, &desc, actor);
	177	if (desc.written)
	178	return desc.written;
	179	return desc.error;
	180	}
	181	EXPORT_SYMBOL_GPL(xip_file_sendfile);
	182
	183	/*
	184	* __xip_unmap is invoked from xip_unmap and
	185	* xip_write
	186	*
	187	* This function walks all vmas of the address_space and unmaps the
a76c0b97	188	* __xip_sparse_page when found at pgoff.
ceffc078 CO	189	*/
	190	static void
	191	__xip_unmap (struct address_space * mapping,
	192	unsigned long pgoff)
	193	{
	194	struct vm_area_struct *vma;
	195	struct mm_struct *mm;
	196	struct prio_tree_iter iter;
	197	unsigned long address;
	198	pte_t *pte;
	199	pte_t pteval;
c0718806	200	spinlock_t *ptl;
67b02f11	201	struct page *page;
ceffc078	202
a76c0b97 CO	203	page = __xip_sparse_page;
	204	if (!page)
	205	return;
	206
ceffc078 CO	207	spin_lock(&mapping->i_mmap_lock);
	208	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
	209	mm = vma->vm_mm;
	210	address = vma->vm_start +
	211	((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
	212	BUG_ON(address < vma->vm_start \|\| address >= vma->vm_end);
c0718806 HD	213	pte = page_check_address(page, mm, address, &ptl);
c0718806 HD	214	if (pte) {
ceffc078	215	/* Nuke the page table entry. */
082ff0a9	216	flush_cache_page(vma, address, pte_pfn(*pte));
ceffc078	217	pteval = ptep_clear_flush(vma, address, pte);
7de6b805	218	page_remove_rmap(page, vma);
b5810039	219	dec_mm_counter(mm, file_rss);
ceffc078	220	BUG_ON(pte_dirty(pteval));
c0718806	221	pte_unmap_unlock(pte, ptl);
b5810039	222	page_cache_release(page);
ceffc078 CO	223	}
	224	}
	225	spin_unlock(&mapping->i_mmap_lock);
	226	}
	227
	228	/*
	229	* xip_nopage() is invoked via the vma operations vector for a
	230	* mapped memory region to read in file data during a page fault.
	231	*
	232	* This function is derived from filemap_nopage, but used for execute in place
	233	*/
	234	static struct page *
	235	xip_file_nopage(struct vm_area_struct * area,
	236	unsigned long address,
	237	int *type)
	238	{
	239	struct file *file = area->vm_file;
	240	struct address_space *mapping = file->f_mapping;
	241	struct inode *inode = mapping->host;
	242	struct page *page;
	243	unsigned long size, pgoff, endoff;
	244
	245	pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT)
	246	+ area->vm_pgoff;
	247	endoff = ((area->vm_end - area->vm_start) >> PAGE_CACHE_SHIFT)
	248	+ area->vm_pgoff;
	249
	250	size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
a76c0b97 CO	251	if (pgoff >= size)
a76c0b97 CO	252	return NOPAGE_SIGBUS;
ceffc078 CO	253
ceffc078 CO	254	page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0);
a76c0b97	255	if (!IS_ERR(page))
b5810039	256	goto out;
ceffc078	257	if (PTR_ERR(page) != -ENODATA)
a76c0b97	258	return NOPAGE_SIGBUS;
ceffc078 CO	259
	260	/* sparse block */
	261	if ((area->vm_flags & (VM_WRITE \| VM_MAYWRITE)) &&
	262	(area->vm_flags & (VM_SHARED\| VM_MAYSHARE)) &&
	263	(!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
	264	/* maybe shared writable, allocate new block */
	265	page = mapping->a_ops->get_xip_page (mapping,
	266	pgoff*(PAGE_SIZE/512), 1);
	267	if (IS_ERR(page))
a76c0b97	268	return NOPAGE_SIGBUS;
ceffc078 CO	269	/* unmap page at pgoff from all other vmas */
	270	__xip_unmap(mapping, pgoff);
	271	} else {
a76c0b97 CO	272	/* not shared and writable, use xip_sparse_page() */
	273	page = xip_sparse_page();
	274	if (!page)
	275	return NOPAGE_OOM;
ceffc078 CO	276	}
ceffc078 CO	277
b5810039 NP	278	out:
b5810039 NP	279	page_cache_get(page);
ceffc078 CO	280	return page;
	281	}
	282
	283	static struct vm_operations_struct xip_file_vm_ops = {
	284	.nopage = xip_file_nopage,
	285	};
	286
	287	int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
	288	{
	289	BUG_ON(!file->f_mapping->a_ops->get_xip_page);
	290
	291	file_accessed(file);
	292	vma->vm_ops = &xip_file_vm_ops;
	293	return 0;
	294	}
	295	EXPORT_SYMBOL_GPL(xip_file_mmap);
	296
	297	static ssize_t
eb6fe0c3 CO	298	__xip_file_write(struct file filp, const char __user buf,
eb6fe0c3 CO	299	size_t count, loff_t pos, loff_t *ppos)
ceffc078	300	{
eb6fe0c3	301	struct address_space * mapping = filp->f_mapping;
f5e54d6e	302	const struct address_space_operations *a_ops = mapping->a_ops;
ceffc078 CO	303	struct inode *inode = mapping->host;
	304	long status = 0;
	305	struct page *page;
	306	size_t bytes;
ceffc078 CO	307	ssize_t written = 0;
	308
	309	BUG_ON(!mapping->a_ops->get_xip_page);
	310
ceffc078 CO	311	do {
	312	unsigned long index;
	313	unsigned long offset;
	314	size_t copied;
	315
	316	offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
	317	index = pos >> PAGE_CACHE_SHIFT;
	318	bytes = PAGE_CACHE_SIZE - offset;
	319	if (bytes > count)
	320	bytes = count;
	321
	322	/*
	323	* Bring in the user page that we will copy from _first_.
	324	* Otherwise there's a nasty deadlock on copying from the
	325	* same page as we're writing to, without it being marked
	326	* up-to-date.
	327	*/
	328	fault_in_pages_readable(buf, bytes);
	329
	330	page = a_ops->get_xip_page(mapping,
eb6fe0c3	331	index*(PAGE_SIZE/512), 0);
ceffc078 CO	332	if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) {
	333	/* we allocate a new page unmap it */
	334	page = a_ops->get_xip_page(mapping,
eb6fe0c3	335	index*(PAGE_SIZE/512), 1);
ceffc078	336	if (!IS_ERR(page))
eb6fe0c3 CO	337	/* unmap page at pgoff from all other vmas */
eb6fe0c3 CO	338	__xip_unmap(mapping, index);
ceffc078 CO	339	}
	340
	341	if (IS_ERR(page)) {
	342	status = PTR_ERR(page);
	343	break;
	344	}
	345
eb6fe0c3	346	copied = filemap_copy_from_user(page, offset, buf, bytes);
ceffc078 CO	347	flush_dcache_page(page);
	348	if (likely(copied > 0)) {
	349	status = copied;
	350
	351	if (status >= 0) {
	352	written += status;
	353	count -= status;
	354	pos += status;
	355	buf += status;
ceffc078 CO	356	}
	357	}
	358	if (unlikely(copied != bytes))
	359	if (status >= 0)
	360	status = -EFAULT;
	361	if (status < 0)
	362	break;
	363	} while (count);
	364	*ppos = pos;
	365	/*
	366	* No need to use i_size_read() here, the i_size
1b1dcc1b	367	* cannot change under us because we hold i_mutex.
ceffc078 CO	368	*/
	369	if (pos > inode->i_size) {
	370	i_size_write(inode, pos);
	371	mark_inode_dirty(inode);
	372	}
	373
	374	return written ? written : status;
	375	}
	376
eb6fe0c3 CO	377	ssize_t
	378	xip_file_write(struct file filp, const char __user buf, size_t len,
	379	loff_t *ppos)
ceffc078	380	{
eb6fe0c3 CO	381	struct address_space *mapping = filp->f_mapping;
	382	struct inode *inode = mapping->host;
	383	size_t count;
	384	loff_t pos;
	385	ssize_t ret;
ceffc078	386
1b1dcc1b	387	mutex_lock(&inode->i_mutex);
ceffc078	388
eb6fe0c3 CO	389	if (!access_ok(VERIFY_READ, buf, len)) {
	390	ret=-EFAULT;
	391	goto out_up;
ceffc078 CO	392	}
ceffc078 CO	393
ceffc078	394	pos = *ppos;
eb6fe0c3	395	count = len;
ceffc078 CO	396
	397	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
	398
eb6fe0c3 CO	399	/* We can write back this queue in page reclaim */
eb6fe0c3 CO	400	current->backing_dev_info = mapping->backing_dev_info;
ceffc078	401
eb6fe0c3 CO	402	ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode));
	403	if (ret)
	404	goto out_backing;
ceffc078	405	if (count == 0)
eb6fe0c3	406	goto out_backing;
ceffc078	407
d3ac7f89	408	ret = remove_suid(filp->f_path.dentry);
eb6fe0c3 CO	409	if (ret)
eb6fe0c3 CO	410	goto out_backing;
ceffc078	411
870f4817	412	file_update_time(filp);
ceffc078	413
eb6fe0c3	414	ret = __xip_file_write (filp, buf, count, pos, ppos);
ceffc078	415
eb6fe0c3 CO	416	out_backing:
	417	current->backing_dev_info = NULL;
	418	out_up:
1b1dcc1b	419	mutex_unlock(&inode->i_mutex);
ceffc078 CO	420	return ret;
ceffc078 CO	421	}
eb6fe0c3	422	EXPORT_SYMBOL_GPL(xip_file_write);
ceffc078 CO	423
	424	/*
	425	* truncate a page used for execute in place
	426	* functionality is analog to block_truncate_page but does use get_xip_page
	427	* to get the page instead of page cache
	428	*/
	429	int
	430	xip_truncate_page(struct address_space *mapping, loff_t from)
	431	{
	432	pgoff_t index = from >> PAGE_CACHE_SHIFT;
	433	unsigned offset = from & (PAGE_CACHE_SIZE-1);
	434	unsigned blocksize;
	435	unsigned length;
	436	struct page *page;
ceffc078 CO	437
	438	BUG_ON(!mapping->a_ops->get_xip_page);
	439
	440	blocksize = 1 << mapping->host->i_blkbits;
	441	length = offset & (blocksize - 1);
	442
	443	/* Block boundary? Nothing to do */
	444	if (!length)
	445	return 0;
	446
	447	length = blocksize - length;
	448
	449	page = mapping->a_ops->get_xip_page(mapping,
	450	index*(PAGE_SIZE/512), 0);
ceffc078	451	if (!page)
eb6fe0c3	452	return -ENOMEM;
ceffc078	453	if (unlikely(IS_ERR(page))) {
eb6fe0c3	454	if (PTR_ERR(page) == -ENODATA)
ceffc078 CO	455	/* Hole? No need to truncate */
ceffc078 CO	456	return 0;
eb6fe0c3 CO	457	else
eb6fe0c3 CO	458	return PTR_ERR(page);
afa597ba	459	}
01f2705d	460	zero_user_page(page, offset, length, KM_USER0);
eb6fe0c3	461	return 0;
ceffc078 CO	462	}
ceffc078 CO	463	EXPORT_SYMBOL_GPL(xip_truncate_page);