{
const struct address_space_operations *aops = mapping->a_ops;
- if (aops->write_begin) {
- return aops->write_begin(file, mapping, pos, len, flags,
+ return aops->write_begin(file, mapping, pos, len, flags,
pagep, fsdata);
- } else {
- int ret;
- pgoff_t index = pos >> PAGE_CACHE_SHIFT;
- unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
- struct inode *inode = mapping->host;
- struct page *page;
-again:
- page = __grab_cache_page(mapping, index);
- *pagep = page;
- if (!page)
- return -ENOMEM;
-
- if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
- /*
- * There is no way to resolve a short write situation
- * for a !Uptodate page (except by double copying in
- * the caller done by generic_perform_write_2copy).
- *
- * Instead, we have to bring it uptodate here.
- */
- ret = aops->readpage(file, page);
- page_cache_release(page);
- if (ret) {
- if (ret == AOP_TRUNCATED_PAGE)
- goto again;
- return ret;
- }
- goto again;
- }
-
- ret = aops->prepare_write(file, page, offset, offset+len);
- if (ret) {
- unlock_page(page);
- page_cache_release(page);
- if (pos + len > inode->i_size)
- vmtruncate(inode, inode->i_size);
- }
- return ret;
- }
}
EXPORT_SYMBOL(pagecache_write_begin);
struct page *page, void *fsdata)
{
const struct address_space_operations *aops = mapping->a_ops;
- int ret;
-
- if (aops->write_end) {
- mark_page_accessed(page);
- ret = aops->write_end(file, mapping, pos, len, copied,
- page, fsdata);
- } else {
- unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
- struct inode *inode = mapping->host;
-
- flush_dcache_page(page);
- ret = aops->commit_write(file, page, offset, offset+len);
- unlock_page(page);
- mark_page_accessed(page);
- page_cache_release(page);
-
- if (ret < 0) {
- if (pos + len > inode->i_size)
- vmtruncate(inode, inode->i_size);
- } else if (ret > 0)
- ret = min_t(size_t, copied, ret);
- else
- ret = copied;
- }
- return ret;
+ mark_page_accessed(page);
+ return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
}
EXPORT_SYMBOL(pagecache_write_end);
}
EXPORT_SYMBOL(__grab_cache_page);
-static ssize_t generic_perform_write_2copy(struct file *file,
- struct iov_iter *i, loff_t pos)
-{
- struct address_space *mapping = file->f_mapping;
- const struct address_space_operations *a_ops = mapping->a_ops;
- struct inode *inode = mapping->host;
- long status = 0;
- ssize_t written = 0;
-
- do {
- struct page *src_page;
- struct page *page;
- pgoff_t index; /* Pagecache index for current page */
- unsigned long offset; /* Offset into pagecache page */
- unsigned long bytes; /* Bytes to write to page */
- size_t copied; /* Bytes copied from user */
-
- offset = (pos & (PAGE_CACHE_SIZE - 1));
- index = pos >> PAGE_CACHE_SHIFT;
- bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
- iov_iter_count(i));
-
- /*
- * a non-NULL src_page indicates that we're doing the
- * copy via get_user_pages and kmap.
- */
- src_page = NULL;
-
- /*
- * 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.
- *
- * Not only is this an optimisation, but it is also required
- * to check that the address is actually valid, when atomic
- * usercopies are used, below.
- */
- if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
- status = -EFAULT;
- break;
- }
-
- page = __grab_cache_page(mapping, index);
- if (!page) {
- status = -ENOMEM;
- break;
- }
-
- /*
- * non-uptodate pages cannot cope with short copies, and we
- * cannot take a pagefault with the destination page locked.
- * So pin the source page to copy it.
- */
- if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
- unlock_page(page);
-
- src_page = alloc_page(GFP_KERNEL);
- if (!src_page) {
- page_cache_release(page);
- status = -ENOMEM;
- break;
- }
-
- /*
- * Cannot get_user_pages with a page locked for the
- * same reason as we can't take a page fault with a
- * page locked (as explained below).
- */
- copied = iov_iter_copy_from_user(src_page, i,
- offset, bytes);
- if (unlikely(copied == 0)) {
- status = -EFAULT;
- page_cache_release(page);
- page_cache_release(src_page);
- break;
- }
- bytes = copied;
-
- lock_page(page);
- /*
- * Can't handle the page going uptodate here, because
- * that means we would use non-atomic usercopies, which
- * zero out the tail of the page, which can cause
- * zeroes to become transiently visible. We could just
- * use a non-zeroing copy, but the APIs aren't too
- * consistent.
- */
- if (unlikely(!page->mapping || PageUptodate(page))) {
- unlock_page(page);
- page_cache_release(page);
- page_cache_release(src_page);
- continue;
- }
- }
-
- status = a_ops->prepare_write(file, page, offset, offset+bytes);
- if (unlikely(status))
- goto fs_write_aop_error;
-
- if (!src_page) {
- /*
- * Must not enter the pagefault handler here, because
- * we hold the page lock, so we might recursively
- * deadlock on the same lock, or get an ABBA deadlock
- * against a different lock, or against the mmap_sem
- * (which nests outside the page lock). So increment
- * preempt count, and use _atomic usercopies.
- *
- * The page is uptodate so we are OK to encounter a
- * short copy: if unmodified parts of the page are
- * marked dirty and written out to disk, it doesn't
- * really matter.
- */
- pagefault_disable();
- copied = iov_iter_copy_from_user_atomic(page, i,
- offset, bytes);
- pagefault_enable();
- } else {
- void *src, *dst;
- src = kmap_atomic(src_page, KM_USER0);
- dst = kmap_atomic(page, KM_USER1);
- memcpy(dst + offset, src + offset, bytes);
- kunmap_atomic(dst, KM_USER1);
- kunmap_atomic(src, KM_USER0);
- copied = bytes;
- }
- flush_dcache_page(page);
-
- status = a_ops->commit_write(file, page, offset, offset+bytes);
- if (unlikely(status < 0))
- goto fs_write_aop_error;
- if (unlikely(status > 0)) /* filesystem did partial write */
- copied = min_t(size_t, copied, status);
-
- unlock_page(page);
- mark_page_accessed(page);
- page_cache_release(page);
- if (src_page)
- page_cache_release(src_page);
-
- iov_iter_advance(i, copied);
- pos += copied;
- written += copied;
-
- balance_dirty_pages_ratelimited(mapping);
- cond_resched();
- continue;
-
-fs_write_aop_error:
- unlock_page(page);
- page_cache_release(page);
- if (src_page)
- page_cache_release(src_page);
-
- /*
- * prepare_write() may have instantiated a few blocks
- * outside i_size. Trim these off again. Don't need
- * i_size_read because we hold i_mutex.
- */
- if (pos + bytes > inode->i_size)
- vmtruncate(inode, inode->i_size);
- break;
- } while (iov_iter_count(i));
-
- return written ? written : status;
-}
-
static ssize_t generic_perform_write(struct file *file,
struct iov_iter *i, loff_t pos)
{
struct iov_iter i;
iov_iter_init(&i, iov, nr_segs, count, written);
- if (a_ops->write_begin)
- status = generic_perform_write(file, &i, pos);
- else
- status = generic_perform_write_2copy(file, &i, pos);
+ status = generic_perform_write(file, &i, pos);
if (likely(status >= 0)) {
written += status;
projects / linux-2.6-omap-h63xx.git / blobdiff