btrfs: don't call btrfs_handle_fs_error() in qgroup_account_snapshot()

btrfs: don't call btrfs_handle_fs_error() in qgroup_account_snapshot()

There's no need to call btrfs_handle_fs_error() as we are inside a
transaction and we propagate the error returned from
btrfs_write_and_wait_transaction() to the caller and it ends going up the
call chain to btrfs_commit_transaction() (returned by the call to
create_pending_snapshots()), where we jump to the 'unlock_reloc' label
and end up calling cleanup_transaction(), which aborts the transaction.

This is odd given that we have a transaction handle and that in the
transaction commit path any error makes us abort the transaction and,
besides another place inside btrfs_commit_transaction(), it's the only
place that calls btrfs_handle_fs_error().

Remove the btrfs_handle_fs_error() call and replace it with an error
message so that if it happens we know what went wrong during the
transaction commit. Also annotate the condition in the if statement
with 'unlikely' since this is not expected to happen.

We've been wanting to remove btrfs_handle_fs_error(), so this removes
one user that does not even need it.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>