Commit 1de3e3df authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: move mpage_put_bnr_to_bhs()'s functionality to mpage_da_submit_io() 



This massively simplifies the ext4_da_writepages() code path by
completely removing mpage_put_bnr_bhs(), which is almost 100 lines of
code iterating over a set of pages using pagevec_lookup(), and folds
that functionality into mpage_da_submit_io()'s existing
pagevec_lookup() loop.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 3ecdb3a1

fs/ext4/inode.c

+38 −101
Original line number Diff line number Diff line
@@ -2003,7 +2003,8 @@ static void ext4_da_page_release_reservation(struct page *page, 
 *

 * As pages are already locked by write_cache_pages(), we can't use it

 */

static int mpage_da_submit_io(struct mpage_da_data *mpd)

static int mpage_da_submit_io(struct mpage_da_data *mpd,

			      struct ext4_map_blocks *map)

{

	struct pagevec pvec;

	unsigned long index, end;
@@ -2014,6 +2015,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd) 
	unsigned int len, block_start;

	struct buffer_head *bh, *page_bufs = NULL;

	int journal_data = ext4_should_journal_data(inode);

	sector_t pblock = 0, cur_logical = 0;



	BUG_ON(mpd->next_page <= mpd->first_page);

	/*
@@ -2031,7 +2033,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd) 
		if (nr_pages == 0)

			break;

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

			int commit_write = 0;

			int commit_write = 0, redirty_page = 0;

			struct page *page = pvec.pages[i];



			index = page->index;
@@ -2042,6 +2044,12 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd) 
				len = size & ~PAGE_CACHE_MASK;

			else

				len = PAGE_CACHE_SIZE;

			if (map) {

				cur_logical = index << (PAGE_CACHE_SHIFT -

							inode->i_blkbits);

				pblock = map->m_pblk + (cur_logical -

							map->m_lblk);

			}

			index++;



			BUG_ON(!PageLocked(page));
@@ -2068,13 +2076,34 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd) 
			bh = page_bufs = page_buffers(page);

			block_start = 0;

			do {

				/* redirty page if block allocation undone */

				if (!bh || buffer_delay(bh) ||

				    buffer_unwritten(bh))

				if (!bh)

					goto redirty_page;

				if (map && (cur_logical >= map->m_lblk) &&

				    (cur_logical <= (map->m_lblk +

						     (map->m_len - 1)))) {

					if (buffer_delay(bh)) {

						clear_buffer_delay(bh);

						bh->b_blocknr = pblock;

					}

					if (buffer_unwritten(bh) ||

					    buffer_mapped(bh))

						BUG_ON(bh->b_blocknr != pblock);

					if (map->m_flags & EXT4_MAP_UNINIT)

						set_buffer_uninit(bh);

					clear_buffer_unwritten(bh);

				}



				/* redirty page if block allocation undone */

				if (buffer_delay(bh) || buffer_unwritten(bh))

					redirty_page = 1;

				bh = bh->b_this_page;

				block_start += bh->b_size;

			} while ((bh != page_bufs) && (block_start < len));

				cur_logical++;

				pblock++;

			} while (bh != page_bufs);



			if (redirty_page)

				goto redirty_page;



			if (commit_write)

				/* mark the buffer_heads as dirty & uptodate */
@@ -2105,91 +2134,6 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd) 
	return ret;

}



/*

 * mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers

 *

 * the function goes through all passed space and put actual disk

 * block numbers into buffer heads, dropping BH_Delay and BH_Unwritten

 */

static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd,

				 struct ext4_map_blocks *map)

{

	struct inode *inode = mpd->inode;

	struct address_space *mapping = inode->i_mapping;

	int blocks = map->m_len;

	sector_t pblock = map->m_pblk, cur_logical;

	struct buffer_head *head, *bh;

	pgoff_t index, end;

	struct pagevec pvec;

	int nr_pages, i;



	index = map->m_lblk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);

	end = (map->m_lblk + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);

	cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);



	pagevec_init(&pvec, 0);



	while (index <= end) {

		/* XXX: optimize tail */

		nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);

		if (nr_pages == 0)

			break;

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

			struct page *page = pvec.pages[i];



			index = page->index;

			if (index > end)

				break;

			index++;



			BUG_ON(!PageLocked(page));

			BUG_ON(PageWriteback(page));

			BUG_ON(!page_has_buffers(page));



			bh = page_buffers(page);

			head = bh;



			/* skip blocks out of the range */

			do {

				if (cur_logical >= map->m_lblk)

					break;

				cur_logical++;

			} while ((bh = bh->b_this_page) != head);



			do {

				if (cur_logical > map->m_lblk + (blocks - 1))

					break;



				if (buffer_delay(bh) || buffer_unwritten(bh)) {



					BUG_ON(bh->b_bdev != inode->i_sb->s_bdev);



					if (buffer_delay(bh)) {

						clear_buffer_delay(bh);

						bh->b_blocknr = pblock;

					} else {

						/*

						 * unwritten already should have

						 * blocknr assigned. Verify that

						 */

						clear_buffer_unwritten(bh);

						BUG_ON(bh->b_blocknr != pblock);

					}



				} else if (buffer_mapped(bh))

					BUG_ON(bh->b_blocknr != pblock);



				if (map->m_flags & EXT4_MAP_UNINIT)

					set_buffer_uninit(bh);

				cur_logical++;

				pblock++;

			} while ((bh = bh->b_this_page) != head);

		}

		pagevec_release(&pvec);

	}

}





static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,

					sector_t logical, long blk_cnt)

{
@@ -2252,7 +2196,7 @@ static void ext4_print_free_blocks(struct inode *inode) 
static void mpage_da_map_and_submit(struct mpage_da_data *mpd)

{

	int err, blks, get_blocks_flags;

	struct ext4_map_blocks map;

	struct ext4_map_blocks map, *mapp = NULL;

	sector_t next = mpd->b_blocknr;

	unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;

	loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
@@ -2343,6 +2287,7 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd) 
	}

	BUG_ON(blks == 0);



	mapp = &map;

	if (map.m_flags & EXT4_MAP_NEW) {

		struct block_device *bdev = mpd->inode->i_sb->s_bdev;

		int i;
@@ -2351,14 +2296,6 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd) 
			unmap_underlying_metadata(bdev, map.m_pblk + i);

	}



	/*

	 * If blocks are delayed marked, we need to

	 * put actual blocknr and drop delayed bit

	 */

	if ((mpd->b_state & (1 << BH_Delay)) ||

	    (mpd->b_state & (1 << BH_Unwritten)))

		mpage_put_bnr_to_bhs(mpd, &map);



	if (ext4_should_order_data(mpd->inode)) {

		err = ext4_jbd2_file_inode(handle, mpd->inode);

		if (err)
@@ -2382,7 +2319,7 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd) 
	}



submit_io:

	mpage_da_submit_io(mpd);

	mpage_da_submit_io(mpd, mapp);

	mpd->io_done = 1;

}

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