Btrfs: skip looking for delalloc if we don't have ->fill_delalloc (9e487107) · Commits · 戴 / test

We always look for delalloc bytes in our io_tree so we can fill in delalloc. This is fine in most cases, but if we're writing out the btree_inode this is just a superfluous tree search on the io_tree, and if we have a lot of metadata dirty this could be an expensive check. So instead check to see if our io_tree has a ->fill_delalloc op, and if not don't even bother doing the lookup. Thanks, Signed-off-by:

Josef Bacik <josef@redhat.com>

fs/btrfs/extent_io.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -2136,6 +2136,7 @@ static int __extent_writepage(struct page page, struct writeback_control wbc,
		int compressed;
		int write_flags;
		unsigned long nr_written = 0;
		bool fill_delalloc = true;

		if (wbc->sync_mode == WB_SYNC_ALL)
		write_flags = WRITE_SYNC;
		@@ -2166,10 +2167,13 @@ static int __extent_writepage(struct page page, struct writeback_control wbc,

		set_page_extent_mapped(page);

		if (!tree->ops \|\| !tree->ops->fill_delalloc)
		fill_delalloc = false;

		delalloc_start = start;
		delalloc_end = 0;
		page_started = 0;
		if (!epd->extent_locked) {
		if (!epd->extent_locked && fill_delalloc) {
		u64 delalloc_to_write = 0;
		/*
		* make sure the wbc mapping index is at least updated

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