Commit 83f1b680 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: remove unnecessary @nr_written parameters 



We use @nr_written to record how many pages have been started by
btrfs_run_delalloc_range().

Currently there are only two cases that would populate @nr_written:

- Inline extent creation
- Compressed write

But both cases will also set @page_started to one.

In fact, in writepage_delalloc() we have the following code, showing
that @nr_written is really only utilized for above two cases:

	/* did the fill delalloc function already unlock and start
	 * the IO?
	 */
	if (page_started) {
		/*
		 * we've unlocked the page, so we can't update
		 * the mapping's writeback index, just update
		 * nr_to_write.
		 */
		wbc->nr_to_write -= nr_written;
		return 1;
	}

But for such cases, writepage_delalloc() will return 1, and exit
__extent_writepage() without going through __extent_writepage_io().

Thus this means, inside __extent_writepage_io(), we always get
@nr_written as 0.

So this patch is going to remove the unnecessary parameter from the
following functions:

- writepage_delalloc()

  As @nr_written passed in is always the initial value 0.

  Although inside that function, we still need a local @nr_written
  to update wbc->nr_to_write.

- __extent_writepage_io()

  As explained above, @nr_written passed in can only be 0.

  This also means we can remove one update_nr_written() call.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 9270501c

fs/btrfs/extent_io.c

+11 −16
Original line number Diff line number Diff line
@@ -3785,12 +3785,13 @@ static void update_nr_written(struct writeback_control *wbc, 
 * This returns < 0 if there were errors (page still locked)

 */

static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,

		struct page *page, struct writeback_control *wbc,

		unsigned long *nr_written)

		struct page *page, struct writeback_control *wbc)

{

	const u64 page_end = page_offset(page) + PAGE_SIZE - 1;

	u64 delalloc_start = page_offset(page);

	u64 delalloc_to_write = 0;

	/* How many pages are started by btrfs_run_delalloc_range() */

	unsigned long nr_written = 0;

	int ret;

	int page_started = 0;
@@ -3806,7 +3807,7 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, 
			continue;

		}

		ret = btrfs_run_delalloc_range(inode, page, delalloc_start,

				delalloc_end, &page_started, nr_written, wbc);

				delalloc_end, &page_started, &nr_written, wbc);

		if (ret) {

			btrfs_page_set_error(inode->root->fs_info, page,

					     page_offset(page), PAGE_SIZE);
@@ -3829,16 +3830,13 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, 
					 thresh);

	}



	/* did the fill delalloc function already unlock and start

	 * the IO?

	 */

	/* Did btrfs_run_dealloc_range() already unlock and start the IO? */

	if (page_started) {

		/*

		 * we've unlocked the page, so we can't update

		 * the mapping's writeback index, just update

		 * nr_to_write.

		 * We've unlocked the page, so we can't update the mapping's

		 * writeback index, just update nr_to_write.

		 */

		wbc->nr_to_write -= *nr_written;

		wbc->nr_to_write -= nr_written;

		return 1;

	}
@@ -3910,7 +3908,6 @@ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, 
				 struct writeback_control *wbc,

				 struct extent_page_data *epd,

				 loff_t i_size,

				 unsigned long nr_written,

				 int *nr_ret)

{

	struct btrfs_fs_info *fs_info = inode->root->fs_info;
@@ -3929,7 +3926,6 @@ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, 
	if (ret) {

		/* Fixup worker will requeue */

		redirty_page_for_writepage(wbc, page);

		update_nr_written(wbc, nr_written);

		unlock_page(page);

		return 1;

	}
@@ -3938,7 +3934,7 @@ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, 
	 * we don't want to touch the inode after unlocking the page,

	 * so we update the mapping writeback index now

	 */

	update_nr_written(wbc, nr_written + 1);

	update_nr_written(wbc, 1);



	while (cur <= end) {

		u64 disk_bytenr;
@@ -4076,7 +4072,6 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, 
	size_t pg_offset;

	loff_t i_size = i_size_read(inode);

	unsigned long end_index = i_size >> PAGE_SHIFT;

	unsigned long nr_written = 0;



	trace___extent_writepage(page, inode, wbc);
@@ -4105,7 +4100,7 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, 
	}



	if (!epd->extent_locked) {

		ret = writepage_delalloc(BTRFS_I(inode), page, wbc, &nr_written);

		ret = writepage_delalloc(BTRFS_I(inode), page, wbc);

		if (ret == 1)

			return 0;

		if (ret)
@@ -4113,7 +4108,7 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, 
	}



	ret = __extent_writepage_io(BTRFS_I(inode), page, wbc, epd, i_size,

				    nr_written, &nr);

				    &nr);

	if (ret == 1)

		return 0;