Commit 80d197fe authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: make the logic from btrfs_block_can_be_shared() easier to read 



The logic in btrfs_block_can_be_shared() is hard to follow as we have a
lot of conditions in a single if statement including a subexpression with
a logical or and two nested if statements inside the main if statement.

Make this easier to read by using separate if statements that return
immediately when we find a condition that determines if a block can be
or can not be shared.

Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 6e5de50f

fs/btrfs/ctree.c

+24 −16
Original line number Diff line number Diff line
@@ -374,27 +374,35 @@ bool btrfs_block_can_be_shared(struct btrfs_trans_handle *trans, 
			       struct btrfs_root *root,

			       struct extent_buffer *buf)

{

	const u64 buf_gen = btrfs_header_generation(buf);



	/*

	 * Tree blocks not in shareable trees and tree roots are never shared.

	 * If a block was allocated after the last snapshot and the block was

	 * not allocated by tree relocation, we know the block is not shared.

	 */

	if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&

	    buf != root->node &&

	    (btrfs_header_generation(buf) <=

	     btrfs_root_last_snapshot(&root->root_item) ||

	     btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))) {



	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))

		return false;



	if (buf == root->node)

		return false;



	if (buf_gen > btrfs_root_last_snapshot(&root->root_item) &&

	    !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))

		return false;



	if (buf != root->commit_root)

		return true;



	/*

		 * An extent buffer that used to be the commit root may still be

		 * shared because the tree height may have increased and it

		 * became a child of a higher level root. This can happen when

		 * snapshotting a subvolume created in the current transaction.

	 * An extent buffer that used to be the commit root may still be shared

	 * because the tree height may have increased and it became a child of a

	 * higher level root. This can happen when snapshotting a subvolume

	 * created in the current transaction.

	 */

		if (btrfs_header_generation(buf) == trans->transid)

	if (buf_gen == trans->transid)

		return true;

	}



	return false;

}