Add a 00-INDEX file to Documentation/sysctl/
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / filemap_xip.c
blob32132f3cd641a9bdea85c101aebfb51315ee0456
1 /*
2 * linux/mm/filemap_xip.c
4 * Copyright (C) 2005 IBM Corporation
5 * Author: Carsten Otte <cotte@de.ibm.com>
7 * derived from linux/mm/filemap.c - Copyright (C) Linus Torvalds
9 */
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 <linux/sched.h>
17 #include <asm/tlbflush.h>
20 * We do use our own empty page to avoid interference with other users
21 * of ZERO_PAGE(), such as /dev/zero
23 static struct page *__xip_sparse_page;
25 static struct page *xip_sparse_page(void)
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);
39 return __xip_sparse_page;
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.
47 * Note the struct file* is not used at all. It may be NULL.
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)
57 struct inode *inode = mapping->host;
58 unsigned long index, end_index, offset;
59 loff_t isize;
61 BUG_ON(!mapping->a_ops->get_xip_page);
63 index = *ppos >> PAGE_CACHE_SHIFT;
64 offset = *ppos & ~PAGE_CACHE_MASK;
66 isize = i_size_read(inode);
67 if (!isize)
68 goto out;
70 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
71 for (;;) {
72 struct page *page;
73 unsigned long nr, ret;
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;
85 nr = nr - offset;
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 */
94 page = ZERO_PAGE(0);
95 } else {
96 desc->error = PTR_ERR(page);
97 goto out;
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.
105 if (mapping_writably_mapped(mapping))
106 flush_dcache_page(page);
109 * Ok, we have the page, so now we can copy it to user space...
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).
117 ret = actor(desc, page, offset, nr);
118 offset += ret;
119 index += offset >> PAGE_CACHE_SHIFT;
120 offset &= ~PAGE_CACHE_MASK;
122 if (ret == nr && desc->count)
123 continue;
124 goto out;
126 no_xip_page:
127 /* Did not get the page. Report it */
128 desc->error = -EIO;
129 goto out;
132 out:
133 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
134 if (filp)
135 file_accessed(filp);
138 ssize_t
139 xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
141 read_descriptor_t desc;
143 if (!access_ok(VERIFY_WRITE, buf, len))
144 return -EFAULT;
146 desc.written = 0;
147 desc.arg.buf = buf;
148 desc.count = len;
149 desc.error = 0;
151 do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
152 ppos, &desc, file_read_actor);
154 if (desc.written)
155 return desc.written;
156 else
157 return desc.error;
159 EXPORT_SYMBOL_GPL(xip_file_read);
162 * __xip_unmap is invoked from xip_unmap and
163 * xip_write
165 * This function walks all vmas of the address_space and unmaps the
166 * __xip_sparse_page when found at pgoff.
168 static void
169 __xip_unmap (struct address_space * mapping,
170 unsigned long pgoff)
172 struct vm_area_struct *vma;
173 struct mm_struct *mm;
174 struct prio_tree_iter iter;
175 unsigned long address;
176 pte_t *pte;
177 pte_t pteval;
178 spinlock_t *ptl;
179 struct page *page;
181 page = __xip_sparse_page;
182 if (!page)
183 return;
185 spin_lock(&mapping->i_mmap_lock);
186 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
187 mm = vma->vm_mm;
188 address = vma->vm_start +
189 ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
190 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
191 pte = page_check_address(page, mm, address, &ptl);
192 if (pte) {
193 /* Nuke the page table entry. */
194 flush_cache_page(vma, address, pte_pfn(*pte));
195 pteval = ptep_clear_flush(vma, address, pte);
196 page_remove_rmap(page, vma);
197 dec_mm_counter(mm, file_rss);
198 BUG_ON(pte_dirty(pteval));
199 pte_unmap_unlock(pte, ptl);
200 page_cache_release(page);
203 spin_unlock(&mapping->i_mmap_lock);
207 * xip_fault() is invoked via the vma operations vector for a
208 * mapped memory region to read in file data during a page fault.
210 * This function is derived from filemap_fault, but used for execute in place
212 static int xip_file_fault(struct vm_area_struct *area, struct vm_fault *vmf)
214 struct file *file = area->vm_file;
215 struct address_space *mapping = file->f_mapping;
216 struct inode *inode = mapping->host;
217 struct page *page;
218 pgoff_t size;
220 /* XXX: are VM_FAULT_ codes OK? */
222 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
223 if (vmf->pgoff >= size)
224 return VM_FAULT_SIGBUS;
226 page = mapping->a_ops->get_xip_page(mapping,
227 vmf->pgoff*(PAGE_SIZE/512), 0);
228 if (!IS_ERR(page))
229 goto out;
230 if (PTR_ERR(page) != -ENODATA)
231 return VM_FAULT_OOM;
233 /* sparse block */
234 if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) &&
235 (area->vm_flags & (VM_SHARED| VM_MAYSHARE)) &&
236 (!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
237 /* maybe shared writable, allocate new block */
238 page = mapping->a_ops->get_xip_page(mapping,
239 vmf->pgoff*(PAGE_SIZE/512), 1);
240 if (IS_ERR(page))
241 return VM_FAULT_SIGBUS;
242 /* unmap page at pgoff from all other vmas */
243 __xip_unmap(mapping, vmf->pgoff);
244 } else {
245 /* not shared and writable, use xip_sparse_page() */
246 page = xip_sparse_page();
247 if (!page)
248 return VM_FAULT_OOM;
251 out:
252 page_cache_get(page);
253 vmf->page = page;
254 return 0;
257 static struct vm_operations_struct xip_file_vm_ops = {
258 .fault = xip_file_fault,
261 int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
263 BUG_ON(!file->f_mapping->a_ops->get_xip_page);
265 file_accessed(file);
266 vma->vm_ops = &xip_file_vm_ops;
267 vma->vm_flags |= VM_CAN_NONLINEAR;
268 return 0;
270 EXPORT_SYMBOL_GPL(xip_file_mmap);
272 static ssize_t
273 __xip_file_write(struct file *filp, const char __user *buf,
274 size_t count, loff_t pos, loff_t *ppos)
276 struct address_space * mapping = filp->f_mapping;
277 const struct address_space_operations *a_ops = mapping->a_ops;
278 struct inode *inode = mapping->host;
279 long status = 0;
280 struct page *page;
281 size_t bytes;
282 ssize_t written = 0;
284 BUG_ON(!mapping->a_ops->get_xip_page);
286 do {
287 unsigned long index;
288 unsigned long offset;
289 size_t copied;
290 char *kaddr;
292 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
293 index = pos >> PAGE_CACHE_SHIFT;
294 bytes = PAGE_CACHE_SIZE - offset;
295 if (bytes > count)
296 bytes = count;
298 page = a_ops->get_xip_page(mapping,
299 index*(PAGE_SIZE/512), 0);
300 if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) {
301 /* we allocate a new page unmap it */
302 page = a_ops->get_xip_page(mapping,
303 index*(PAGE_SIZE/512), 1);
304 if (!IS_ERR(page))
305 /* unmap page at pgoff from all other vmas */
306 __xip_unmap(mapping, index);
309 if (IS_ERR(page)) {
310 status = PTR_ERR(page);
311 break;
314 fault_in_pages_readable(buf, bytes);
315 kaddr = kmap_atomic(page, KM_USER0);
316 copied = bytes -
317 __copy_from_user_inatomic_nocache(kaddr, buf, bytes);
318 kunmap_atomic(kaddr, KM_USER0);
319 flush_dcache_page(page);
321 if (likely(copied > 0)) {
322 status = copied;
324 if (status >= 0) {
325 written += status;
326 count -= status;
327 pos += status;
328 buf += status;
331 if (unlikely(copied != bytes))
332 if (status >= 0)
333 status = -EFAULT;
334 if (status < 0)
335 break;
336 } while (count);
337 *ppos = pos;
339 * No need to use i_size_read() here, the i_size
340 * cannot change under us because we hold i_mutex.
342 if (pos > inode->i_size) {
343 i_size_write(inode, pos);
344 mark_inode_dirty(inode);
347 return written ? written : status;
350 ssize_t
351 xip_file_write(struct file *filp, const char __user *buf, size_t len,
352 loff_t *ppos)
354 struct address_space *mapping = filp->f_mapping;
355 struct inode *inode = mapping->host;
356 size_t count;
357 loff_t pos;
358 ssize_t ret;
360 mutex_lock(&inode->i_mutex);
362 if (!access_ok(VERIFY_READ, buf, len)) {
363 ret=-EFAULT;
364 goto out_up;
367 pos = *ppos;
368 count = len;
370 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
372 /* We can write back this queue in page reclaim */
373 current->backing_dev_info = mapping->backing_dev_info;
375 ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode));
376 if (ret)
377 goto out_backing;
378 if (count == 0)
379 goto out_backing;
381 ret = remove_suid(filp->f_path.dentry);
382 if (ret)
383 goto out_backing;
385 file_update_time(filp);
387 ret = __xip_file_write (filp, buf, count, pos, ppos);
389 out_backing:
390 current->backing_dev_info = NULL;
391 out_up:
392 mutex_unlock(&inode->i_mutex);
393 return ret;
395 EXPORT_SYMBOL_GPL(xip_file_write);
398 * truncate a page used for execute in place
399 * functionality is analog to block_truncate_page but does use get_xip_page
400 * to get the page instead of page cache
403 xip_truncate_page(struct address_space *mapping, loff_t from)
405 pgoff_t index = from >> PAGE_CACHE_SHIFT;
406 unsigned offset = from & (PAGE_CACHE_SIZE-1);
407 unsigned blocksize;
408 unsigned length;
409 struct page *page;
411 BUG_ON(!mapping->a_ops->get_xip_page);
413 blocksize = 1 << mapping->host->i_blkbits;
414 length = offset & (blocksize - 1);
416 /* Block boundary? Nothing to do */
417 if (!length)
418 return 0;
420 length = blocksize - length;
422 page = mapping->a_ops->get_xip_page(mapping,
423 index*(PAGE_SIZE/512), 0);
424 if (!page)
425 return -ENOMEM;
426 if (unlikely(IS_ERR(page))) {
427 if (PTR_ERR(page) == -ENODATA)
428 /* Hole? No need to truncate */
429 return 0;
430 else
431 return PTR_ERR(page);
433 zero_user_page(page, offset, length, KM_USER0);
434 return 0;
436 EXPORT_SYMBOL_GPL(xip_truncate_page);