Commit 5f6b2e5c authored Mar 13, 2020 by Josef Bacik Committed by David Sterba Mar 23, 2020

btrfs: reloc: reorder reservation before root selection



Since we're not only checking for metadata reservations but also if we
need to throttle our delayed ref generation, reorder
reserve_metadata_space() above the select_one_root() call in
relocate_tree_block().

The reason we want this is because select_reloc_root() will mess with
the backref cache, and if we're going to bail we want to be able to
cleanly remove this node from the backref cache and come back along to
regenerate it.  Move it up so this is the first thing we do to make
restarting cleaner.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent d7ff00f6

fs/btrfs/relocation.c

+8 −6

Original line number	Diff line number	Diff line
		@@ -3177,6 +3177,14 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
		if (!node)
		return 0;

		/*
		* If we fail here we want to drop our backref_node because we are going
		* to start over and regenerate the tree for it.
		*/
		ret = reserve_metadata_space(trans, rc, node);
		if (ret)
		goto out;

		BUG_ON(node->processed);
		root = select_one_root(node);
		if (root == ERR_PTR(-ENOENT)) {
		@@ -3184,12 +3192,6 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
		goto out;
		}

		if (!root \|\| test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
		ret = reserve_metadata_space(trans, rc, node);
		if (ret)
		goto out;
		}

		if (root) {
		if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
		BUG_ON(node->new_bytenr);

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