bcachefs: Journal writes are now IOPRIO_CLASS_RT

System performance is particularly sensitive to journal write latency,
the number of outstanding journal writes is bounded and we can't issue
journal flushes until other journal writes have completed.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Author: Kent Overstreet

fs/bcachefs/journal_io.c

@@ -17,6 +17,7 @@
 #include "sb-clean.h"
 #include "trace.h"
 
+#include <linux/ioprio.h>
 #include <linux/string_choices.h>
 
 void bch2_journal_pos_from_member_info_set(struct bch_fs *c)
@@ -1763,6 +1764,7 @@ static CLOSURE_CALLBACK(journal_write_submit)
 		bio->bi_iter.bi_sector	= ptr->offset;
 		bio->bi_end_io		= journal_write_endio;
 		bio->bi_private		= ca;
+		bio->bi_ioprio		= IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 0);
 
 		BUG_ON(bio->bi_iter.bi_sector == ca->prev_journal_sector);
 		ca->prev_journal_sector = bio->bi_iter.bi_sector;