And propagate the error up the stack so we can add the stripe
to no_stripes_list and retry our log operation later.  This avoids
blocking raid5d due to reclaim, an it allows to get rid of the
deadlock-prone GFP_NOFAIL allocation.

shli: add missing mempool_destroy()
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NNeilBrown <neilb@suse.com>