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Commit a7b334de authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 

* 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext3: Try to avoid starting a transaction in writepage for data=writepage
  block_write_full_page: switch synchronous writes to use WRITE_SYNC_PLUG
parents 72ae9e09 430db323

fs/buffer.c

+12 −1
Original line number Diff line number Diff line
@@ -1596,6 +1596,16 @@ EXPORT_SYMBOL(unmap_underlying_metadata); 
 * locked buffer.   This only can happen if someone has written the buffer

 * directly, with submit_bh().  At the address_space level PageWriteback

 * prevents this contention from occurring.

 *

 * If block_write_full_page() is called with wbc->sync_mode ==

 * WB_SYNC_ALL, the writes are posted using WRITE_SYNC_PLUG; this

 * causes the writes to be flagged as synchronous writes, but the

 * block device queue will NOT be unplugged, since usually many pages

 * will be pushed to the out before the higher-level caller actually

 * waits for the writes to be completed.  The various wait functions,

 * such as wait_on_writeback_range() will ultimately call sync_page()

 * which will ultimately call blk_run_backing_dev(), which will end up

 * unplugging the device queue.

 */

static int __block_write_full_page(struct inode *inode, struct page *page,

			get_block_t *get_block, struct writeback_control *wbc)
@@ -1606,7 +1616,8 @@ static int __block_write_full_page(struct inode *inode, struct page *page, 
	struct buffer_head *bh, *head;

	const unsigned blocksize = 1 << inode->i_blkbits;

	int nr_underway = 0;

	int write_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);

	int write_op = (wbc->sync_mode == WB_SYNC_ALL ?

			WRITE_SYNC_PLUG : WRITE);



	BUG_ON(!PageLocked(page));

fs/ext3/inode.c

+18 −5
Original line number Diff line number Diff line
@@ -1521,12 +1521,16 @@ static int ext3_ordered_writepage(struct page *page, 
	if (!page_has_buffers(page)) {

		create_empty_buffers(page, inode->i_sb->s_blocksize,

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

	} else if (!walk_page_buffers(NULL, page_buffers(page), 0, PAGE_CACHE_SIZE, NULL, buffer_unmapped)) {

		/* Provide NULL instead of get_block so that we catch bugs if buffers weren't really mapped */

		page_bufs = page_buffers(page);

	} else {

		page_bufs = page_buffers(page);

		if (!walk_page_buffers(NULL, page_bufs, 0, PAGE_CACHE_SIZE,

				       NULL, buffer_unmapped)) {

			/* Provide NULL get_block() to catch bugs if buffers

			 * weren't really mapped */

			return block_write_full_page(page, NULL, wbc);

		}

	page_bufs = page_buffers(page);



	}

	handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));



	if (IS_ERR(handle)) {
@@ -1581,6 +1585,15 @@ static int ext3_writeback_writepage(struct page *page, 
	if (ext3_journal_current_handle())

		goto out_fail;



	if (page_has_buffers(page)) {

		if (!walk_page_buffers(NULL, page_buffers(page), 0,

				      PAGE_CACHE_SIZE, NULL, buffer_unmapped)) {

			/* Provide NULL get_block() to catch bugs if buffers

			 * weren't really mapped */

			return block_write_full_page(page, NULL, wbc);

		}

	}



	handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));

	if (IS_ERR(handle)) {

		ret = PTR_ERR(handle);