md/r5cache: generate R5LOG_PAYLOAD_FLUSH

In r5c_finish_stripe_write_out(), R5LOG_PAYLOAD_FLUSH is append to
log->current_io.

Appending R5LOG_PAYLOAD_FLUSH in quiesce needs extra writes to
journal. To simplify the logic, we just skip R5LOG_PAYLOAD_FLUSH in
quiesce.

Even R5LOG_PAYLOAD_FLUSH supports multiple stripes per payload.
However, current implementation is one stripe per R5LOG_PAYLOAD_FLUSH,
which is simpler.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index f85ab2744bfbd354af16ecdb830da2ff7228ee64..64493132470b527683771ba2d5d3dcd2d2ea606e 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -593,7 +593,7 @@ static void r5l_log_endio(struct bio *bio)
 
        spin_lock_irqsave(&log->io_list_lock, flags);
        __r5l_set_io_unit_state(io, IO_UNIT_IO_END);
-       if (log->need_cache_flush)
+       if (log->need_cache_flush && !list_empty(&io->stripe_list))
                r5l_move_to_end_ios(log);
        else
                r5l_log_run_stripes(log);
@@ -621,9 +621,11 @@ static void r5l_log_endio(struct bio *bio)
                        bio_endio(bi);
                        atomic_dec(&io->pending_stripe);
                }
-               if (atomic_read(&io->pending_stripe) == 0)
-                       __r5l_stripe_write_finished(io);
        }
+
+       /* finish flush only io_unit and PAYLOAD_FLUSH only io_unit */
+       if (atomic_read(&io->pending_stripe) == 0)
+               __r5l_stripe_write_finished(io);
 }
 
 static void r5l_do_submit_io(struct r5l_log *log, struct r5l_io_unit *io)
@@ -845,6 +847,41 @@ static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
        r5_reserve_log_entry(log, io);
 }
 
+static void r5l_append_flush_payload(struct r5l_log *log, sector_t sect)
+{
+       struct mddev *mddev = log->rdev->mddev;
+       struct r5conf *conf = mddev->private;
+       struct r5l_io_unit *io;
+       struct r5l_payload_flush *payload;
+       int meta_size;
+
+       /*
+        * payload_flush requires extra writes to the journal.
+        * To avoid handling the extra IO in quiesce, just skip
+        * flush_payload
+        */
+       if (conf->quiesce)
+               return;
+
+       mutex_lock(&log->io_mutex);
+       meta_size = sizeof(struct r5l_payload_flush) + sizeof(__le64);
+
+       if (r5l_get_meta(log, meta_size)) {
+               mutex_unlock(&log->io_mutex);
+               return;
+       }
+
+       /* current implementation is one stripe per flush payload */
+       io = log->current_io;
+       payload = page_address(io->meta_page) + io->meta_offset;
+       payload->header.type = cpu_to_le16(R5LOG_PAYLOAD_FLUSH);
+       payload->header.flags = cpu_to_le16(0);
+       payload->size = cpu_to_le32(sizeof(__le64));
+       payload->flush_stripes[0] = cpu_to_le64(sect);
+       io->meta_offset += meta_size;
+       mutex_unlock(&log->io_mutex);
+}
+
 static int r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
                           int data_pages, int parity_pages)
 {
@@ -2784,6 +2821,8 @@ void r5c_finish_stripe_write_out(struct r5conf *conf,
                atomic_dec(&conf->r5c_flushing_full_stripes);
                atomic_dec(&conf->r5c_cached_full_stripes);
        }
+
+       r5l_append_flush_payload(log, sh->sector);
 }
 
 int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh)