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Commit a97adc9f authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: use larger nr_to_write for larger extents 



When btrfs fills a large delayed allocation extent, it is a good idea
to try and convince the write_cache_pages caller to go ahead and
write a good chunk of that extent.  The extra IO is basically free
because we know it is contiguous.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 4f878e84

fs/btrfs/extent_io.c

+9 −5
Original line number Diff line number Diff line
@@ -2135,6 +2135,7 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, 
	delalloc_end = 0;

	page_started = 0;

	if (!epd->extent_locked) {

		u64 delalloc_to_write;

		/*

		 * make sure the wbc mapping index is at least updated

		 * to this page.
@@ -2154,6 +2155,14 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, 
			tree->ops->fill_delalloc(inode, page, delalloc_start,

						 delalloc_end, &page_started,

						 &nr_written);

			delalloc_to_write = (delalloc_end -

					max_t(u64, page_offset(page),

					      delalloc_start) + 1) >>

				        PAGE_CACHE_SHIFT;

			if (wbc->nr_to_write < delalloc_to_write) {

				wbc->nr_to_write = min_t(long, 8192,

						 delalloc_to_write);

			}

			delalloc_start = delalloc_end + 1;

		}
@@ -2350,7 +2359,6 @@ static int extent_write_cache_pages(struct extent_io_tree *tree, 
			     writepage_t writepage, void *data,

			     void (*flush_fn)(void *))

{

	struct backing_dev_info *bdi = mapping->backing_dev_info;

	int ret = 0;

	int done = 0;

	struct pagevec pvec;
@@ -2425,10 +2433,6 @@ static int extent_write_cache_pages(struct extent_io_tree *tree, 
			}

			if (ret || wbc->nr_to_write <= 0)

				done = 1;

			if (wbc->nonblocking && bdi_write_congested(bdi)) {

				wbc->encountered_congestion = 1;

				done = 1;

			}

		}

		pagevec_release(&pvec);

		cond_resched();