scsi: ->queue_rq can't sleep

The blk-mq ->queue_rq method is always called from process context,
but might have preemption disabled.  This means we still always
have to use GFP_ATOMIC for memory allocations, and thus need to
revert part of commit 3c356bde1 ("scsi: stop passing a gfp_mask
argument down the command setup path").

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>

drivers/scsi/scsi_lib.c

@@ -591,7 +591,6 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb, bool mq)
 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, bool mq)
 {
 	struct scatterlist *first_chunk = NULL;
-	gfp_t gfp_mask = mq ? GFP_NOIO : GFP_ATOMIC;
 	int ret;
 
 	BUG_ON(!nents);
@@ -606,7 +605,7 @@ static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, bool mq)
 	}
 
 	ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
-			       first_chunk, gfp_mask, scsi_sg_alloc);
+			       first_chunk, GFP_ATOMIC, scsi_sg_alloc);
 	if (unlikely(ret))
 		scsi_free_sgtable(sdb, mq);
 	return ret;