-static int bget_one(handle_t *handle, struct buffer_head *bh)
-{
- get_bh(bh);
- return 0;
-}
-
-static int bput_one(handle_t *handle, struct buffer_head *bh)
-{
- put_bh(bh);
- return 0;
-}
-
-/*
- * Note that we don't need to start a transaction unless we're journaling data
- * because we should have holes filled from ext4_page_mkwrite(). We even don't
- * need to file the inode to the transaction's list in ordered mode because if
- * we are writing back data added by write(), the inode is already there and if
- * we are writing back data modified via mmap(), noone guarantees in which
- * transaction the data will hit the disk. In case we are journaling data, we
- * cannot start transaction directly because transaction start ranks above page
- * lock so we have to do some magic.
- *
- * In all journaling modes block_write_full_page() will start the I/O.
- *
- * Problem:
- *
- * ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
- * ext4_writepage()
- *
- * Similar for:
- *
- * ext4_file_write() -> generic_file_write() -> __alloc_pages() -> ...
- *
- * Same applies to ext4_get_block(). We will deadlock on various things like
- * lock_journal and i_data_sem
- *
- * Setting PF_MEMALLOC here doesn't work - too many internal memory
- * allocations fail.
- *
- * 16May01: If we're reentered then journal_current_handle() will be
- * non-zero. We simply *return*.
- *
- * 1 July 2001: @@@ FIXME:
- * In journalled data mode, a data buffer may be metadata against the
- * current transaction. But the same file is part of a shared mapping
- * and someone does a writepage() on it.
- *
- * We will move the buffer onto the async_data list, but *after* it has
- * been dirtied. So there's a small window where we have dirty data on
- * BJ_Metadata.
- *
- * Note that this only applies to the last partial page in the file. The
- * bit which block_write_full_page() uses prepare/commit for. (That's
- * broken code anyway: it's wrong for msync()).
- *
- * It's a rare case: affects the final partial page, for journalled data
- * where the file is subject to bith write() and writepage() in the same
- * transction. To fix it we'll need a custom block_write_full_page().
- * We'll probably need that anyway for journalling writepage() output.
- *
- * We don't honour synchronous mounts for writepage(). That would be
- * disastrous. Any write() or metadata operation will sync the fs for
- * us.
- *
- */
-static int __ext4_normal_writepage(struct page *page,
- struct writeback_control *wbc)
-{
- struct inode *inode = page->mapping->host;
-
- if (test_opt(inode->i_sb, NOBH))
- return nobh_writepage(page, noalloc_get_block_write, wbc);
- else
- return block_write_full_page(page, noalloc_get_block_write,
- wbc);
-}
-
-static int ext4_normal_writepage(struct page *page,
- struct writeback_control *wbc)
-{
- struct inode *inode = page->mapping->host;
- loff_t size = i_size_read(inode);
- loff_t len;
-
- trace_ext4_normal_writepage(inode, page);
- J_ASSERT(PageLocked(page));
- if (page->index == size >> PAGE_CACHE_SHIFT)
- len = size & ~PAGE_CACHE_MASK;
- else
- len = PAGE_CACHE_SIZE;
-
- if (page_has_buffers(page)) {
- /* if page has buffers it should all be mapped
- * and allocated. If there are not buffers attached
- * to the page we know the page is dirty but it lost
- * buffers. That means that at some moment in time
- * after write_begin() / write_end() has been called
- * all buffers have been clean and thus they must have been
- * written at least once. So they are all mapped and we can
- * happily proceed with mapping them and writing the page.
- */
- BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
- ext4_bh_unmapped_or_delay));
- }
-
- if (!ext4_journal_current_handle())
- return __ext4_normal_writepage(page, wbc);
-
- redirty_page_for_writepage(wbc, page);
- unlock_page(page);
- return 0;
-}
-
-static int __ext4_journalled_writepage(struct page *page,
- struct writeback_control *wbc)
-{
- struct address_space *mapping = page->mapping;
- struct inode *inode = mapping->host;
- struct buffer_head *page_bufs;
- handle_t *handle = NULL;
- int ret = 0;
- int err;
-
- ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
- noalloc_get_block_write);
- if (ret != 0)
- goto out_unlock;
-
- page_bufs = page_buffers(page);
- walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE, NULL,
- bget_one);
- /* As soon as we unlock the page, it can go away, but we have
- * references to buffers so we are safe */
- unlock_page(page);
-
- handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- goto out;
- }
-
- ret = walk_page_buffers(handle, page_bufs, 0,
- PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
-
- err = walk_page_buffers(handle, page_bufs, 0,
- PAGE_CACHE_SIZE, NULL, write_end_fn);
- if (ret == 0)
- ret = err;
- err = ext4_journal_stop(handle);
- if (!ret)
- ret = err;
-
- walk_page_buffers(handle, page_bufs, 0,
- PAGE_CACHE_SIZE, NULL, bput_one);
- EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
- goto out;
-
-out_unlock:
- unlock_page(page);
-out:
- return ret;
-}
-
-static int ext4_journalled_writepage(struct page *page,
- struct writeback_control *wbc)
-{
- struct inode *inode = page->mapping->host;
- loff_t size = i_size_read(inode);
- loff_t len;
-
- trace_ext4_journalled_writepage(inode, page);
- J_ASSERT(PageLocked(page));
- if (page->index == size >> PAGE_CACHE_SHIFT)
- len = size & ~PAGE_CACHE_MASK;
- else
- len = PAGE_CACHE_SIZE;
-
- if (page_has_buffers(page)) {
- /* if page has buffers it should all be mapped
- * and allocated. If there are not buffers attached
- * to the page we know the page is dirty but it lost
- * buffers. That means that at some moment in time
- * after write_begin() / write_end() has been called
- * all buffers have been clean and thus they must have been
- * written at least once. So they are all mapped and we can
- * happily proceed with mapping them and writing the page.
- */
- BUG_ON(walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
- ext4_bh_unmapped_or_delay));
- }
-
- if (ext4_journal_current_handle())
- goto no_write;
-
- if (PageChecked(page)) {
- /*
- * It's mmapped pagecache. Add buffers and journal it. There
- * doesn't seem much point in redirtying the page here.
- */
- ClearPageChecked(page);
- return __ext4_journalled_writepage(page, wbc);
- } else {
- /*
- * It may be a page full of checkpoint-mode buffers. We don't
- * really know unless we go poke around in the buffer_heads.
- * But block_write_full_page will do the right thing.
- */
- return block_write_full_page(page, noalloc_get_block_write,
- wbc);
- }
-no_write:
- redirty_page_for_writepage(wbc, page);
- unlock_page(page);
- return 0;
-}
-