Commit 9d0d47d5 authored Mar 21, 2023 by Filipe Manana Committed by David Sterba Apr 17, 2023

btrfs: update flush method assertion when reserving space



When reserving space, at space-info.c:__reserve_bytes(), we assert that
either the current task is not holding a transacion handle, or, if it is,
that the flush method is not BTRFS_RESERVE_FLUSH_ALL. This is because that
flush method can trigger transaction commits, and therefore could lead to
a deadlock.

However there are other 2 flush methods that can trigger transaction
commits:

1) BTRFS_RESERVE_FLUSH_ALL_STEAL
2) BTRFS_RESERVE_FLUSH_EVICT

So update the assertion to check the flush method is also not one those
two methods if the current task is holding a transaction handle.

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

parent 1a332502

fs/btrfs/space-info.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -1603,7 +1603,18 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info,
		bool pending_tickets;

		ASSERT(orig_bytes);
		ASSERT(!current->journal_info \|\| flush != BTRFS_RESERVE_FLUSH_ALL);
		/*
		* If have a transaction handle (current->journal_info != NULL), then
		* the flush method can not be neither BTRFS_RESERVE_FLUSH_ALL* nor
		* BTRFS_RESERVE_FLUSH_EVICT, as we could deadlock because those
		* flushing methods can trigger transaction commits.
		*/
		if (current->journal_info) {
		/* One assert per line for easier debugging. */
		ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL);
		ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL_STEAL);
		ASSERT(flush != BTRFS_RESERVE_FLUSH_EVICT);
		}

		if (flush == BTRFS_RESERVE_FLUSH_DATA)
		async_work = &fs_info->async_data_reclaim_work;