btrfs: don't arbitrarily slow down delalloc if we're committing

We have a random schedule_timeout() if the current transaction is
committing, which seems to be a holdover from the original delalloc
reservation code.

Remove this, we have the proper flushing stuff, we shouldn't be hoping
for random timing things to make everything work.  This just induces
latency for no reason.

CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/delalloc-space.c

@@ -322,9 +322,6 @@ int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes,
 	} else {
 		if (current->journal_info)
 			flush = BTRFS_RESERVE_FLUSH_LIMIT;
-
-		if (btrfs_transaction_in_commit(fs_info))
-			schedule_timeout(1);
 	}
 
 	num_bytes = ALIGN(num_bytes, fs_info->sectorsize);