Commit 4f01b02c authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: simple cleanups to write_cache_pages_da() 



Eliminate duplicate code, unneeded variables, etc., to make it easier
to understand the code.  No behavioral changes were made in this patch.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 8eb9e5ce

fs/ext4/inode.c

+48 −67
Original line number Diff line number Diff line
@@ -2723,17 +2723,14 @@ static int write_cache_pages_da(struct address_space *mapping, 
				struct mpage_da_data *mpd,

				pgoff_t *done_index)

{

	struct inode *inode = mpd->inode;

	struct buffer_head	*bh, *head;

	sector_t logical;

	int ret = 0;

	int done = 0;

	struct inode		*inode = mpd->inode;

	struct pagevec		pvec;

	unsigned nr_pages;

	pgoff_t index;

	pgoff_t end;		/* Inclusive */

	unsigned int		nr_pages;

	sector_t		logical;

	pgoff_t			index, end;

	long			nr_to_write = wbc->nr_to_write;

	int tag;

	int			i, tag, ret = 0;



	pagevec_init(&pvec, 0);

	index = wbc->range_start >> PAGE_CACHE_SHIFT;
@@ -2745,13 +2742,11 @@ static int write_cache_pages_da(struct address_space *mapping, 
		tag = PAGECACHE_TAG_DIRTY;



	*done_index = index;

	while (!done && (index <= end)) {

		int i;



	while (index <= end) {

		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,

			      min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);

		if (nr_pages == 0)

			break;

			return 0;



		for (i = 0; i < nr_pages; i++) {

			struct page *page = pvec.pages[i];
@@ -2763,47 +2758,37 @@ static int write_cache_pages_da(struct address_space *mapping, 
			 * mapping. However, page->index will not change

			 * because we have a reference on the page.

			 */

			if (page->index > end) {

				done = 1;

				break;

			}

			if (page->index > end)

				goto out;



			*done_index = page->index + 1;



			lock_page(page);



			/*

			 * Page truncated or invalidated. We can freely skip it

			 * then, even for data integrity operations: the page

			 * has disappeared concurrently, so there could be no

			 * real expectation of this data interity operation

			 * even if there is now a new, dirty page at the same

			 * pagecache address.

			 * If the page is no longer dirty, or its

			 * mapping no longer corresponds to inode we

			 * are writing (which means it has been

			 * truncated or invalidated), or the page is

			 * already under writeback and we are not

			 * doing a data integrity writeback, skip the page

			 */

			if (unlikely(page->mapping != mapping)) {

			if (!PageDirty(page) ||

			    (PageWriteback(page) &&

			     (wbc->sync_mode == WB_SYNC_NONE)) ||

			    unlikely(page->mapping != mapping)) {

			continue_unlock:

				unlock_page(page);

				continue;

			}



			if (!PageDirty(page)) {

				/* someone wrote it for us */

				goto continue_unlock;

			}



			if (PageWriteback(page)) {

				if (wbc->sync_mode != WB_SYNC_NONE)

			if (PageWriteback(page))

				wait_on_page_writeback(page);

				else

					goto continue_unlock;

			}



			BUG_ON(PageWriteback(page));

			if (!clear_page_dirty_for_io(page))

				goto continue_unlock;



			/* BEGIN __mpage_da_writepage */



			/*

			 * Can we merge this page to current extent?

			 */
@@ -2820,8 +2805,7 @@ static int write_cache_pages_da(struct address_space *mapping, 
					 */

					redirty_page_for_writepage(wbc, page);

					unlock_page(page);

					ret = MPAGE_DA_EXTENT_TAIL;

					goto out;

					goto ret_extent_tail;

				}



				/*
@@ -2838,15 +2822,15 @@ static int write_cache_pages_da(struct address_space *mapping, 
				(PAGE_CACHE_SHIFT - inode->i_blkbits);



			if (!page_has_buffers(page)) {

				mpage_add_bh_to_extent(mpd, logical, PAGE_CACHE_SIZE,

				mpage_add_bh_to_extent(mpd, logical,

						       PAGE_CACHE_SIZE,

						       (1 << BH_Dirty) | (1 << BH_Uptodate));

				if (mpd->io_done) {

					ret = MPAGE_DA_EXTENT_TAIL;

					goto out;

				}

				if (mpd->io_done)

					goto ret_extent_tail;

			} else {

				/*

				 * Page with regular buffer heads, just add all dirty ones

				 * Page with regular buffer heads,

				 * just add all dirty ones

				 */

				head = page_buffers(page);

				bh = head;
@@ -2862,18 +2846,19 @@ static int write_cache_pages_da(struct address_space *mapping, 
						mpage_add_bh_to_extent(mpd, logical,

								       bh->b_size,

								       bh->b_state);

						if (mpd->io_done) {

							ret = MPAGE_DA_EXTENT_TAIL;

							goto out;

						}

						if (mpd->io_done)

							goto ret_extent_tail;

					} else if (buffer_dirty(bh) && (buffer_mapped(bh))) {

						/*

						 * mapped dirty buffer. We need to update

						 * the b_state because we look at

						 * b_state in mpage_da_map_blocks. We don't

						 * update b_size because if we find an

						 * unmapped buffer_head later we need to

						 * use the b_state flag of that buffer_head.

						 * mapped dirty buffer. We need

						 * to update the b_state

						 * because we look at b_state

						 * in mpage_da_map_blocks.  We

						 * don't update b_size because

						 * if we find an unmapped

						 * buffer_head later we need to

						 * use the b_state flag of that

						 * buffer_head.

						 */

						if (mpd->b_size == 0)

							mpd->b_state = bh->b_state & BH_FLAGS;
@@ -2882,14 +2867,10 @@ static int write_cache_pages_da(struct address_space *mapping, 
				} while ((bh = bh->b_this_page) != head);

			}



			ret = 0;



			/* END __mpage_da_writepage */



			if (nr_to_write > 0) {

				nr_to_write--;

				if (nr_to_write == 0 &&

				    wbc->sync_mode == WB_SYNC_NONE) {

				    wbc->sync_mode == WB_SYNC_NONE)

					/*

					 * We stop writing back only if we are

					 * not doing integrity sync. In case of
@@ -2900,15 +2881,15 @@ static int write_cache_pages_da(struct address_space *mapping, 
					 * pages, but have not synced all of the

					 * old dirty pages.

					 */

					done = 1;

					break;

				}

					goto out;

			}

		}

		pagevec_release(&pvec);

		cond_resched();

	}

	return ret;

	return 0;

ret_extent_tail:

	ret = MPAGE_DA_EXTENT_TAIL;

out:

	pagevec_release(&pvec);

	cond_resched();