For devices without a volatile write cache we don't need to send a FLUSH
command to ensure writes are stable on disk, and thus can avoid the whole
step of batching up bios for processing by the MD thread.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
drivers/md/raid5-cache.c | 33 +++++++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index b04e908..0d18ed7 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -83,6 +83,8 @@ struct r5l_log {
struct list_head no_space_stripes; /* pending stripes, log has no space */
spinlock_t no_space_stripes_lock;
+
+ bool need_cache_flush;
};
/*
@@ -205,6 +207,22 @@ static void r5l_io_run_stripes(struct r5l_io_unit *io)
}
}
+static void r5l_log_run_stripes(struct r5l_log *log)
+{
+ struct r5l_io_unit *io, *next;
+
+ assert_spin_locked(&log->io_list_lock);
+
+ list_for_each_entry_safe(io, next, &log->running_ios, log_sibling) {
+ /* don't change list order */
+ if (io->state < IO_UNIT_IO_END)
+ break;
+
+ list_move_tail(&io->log_sibling, &log->finished_ios);
+ r5l_io_run_stripes(io);
+ }
+}
+
static void r5l_log_endio(struct bio *bio)
{
struct r5l_io_unit *io = bio->bi_private;
@@ -221,11 +239,15 @@ 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);
- r5l_move_io_unit_list(&log->running_ios, &log->io_end_ios,
- IO_UNIT_IO_END);
+ if (log->need_cache_flush)
+ r5l_move_io_unit_list(&log->running_ios, &log->io_end_ios,
+ IO_UNIT_IO_END);
+ else
+ r5l_log_run_stripes(log);
spin_unlock_irqrestore(&log->io_list_lock, flags);
- md_wakeup_thread(log->rdev->mddev->thread);
+ if (log->need_cache_flush)
+ md_wakeup_thread(log->rdev->mddev->thread);
}
static void r5l_submit_current_io(struct r5l_log *log)
@@ -626,7 +648,8 @@ static void r5l_log_flush_endio(struct bio *bio)
void r5l_flush_stripe_to_raid(struct r5l_log *log)
{
bool do_flush;
- if (!log)
+
+ if (!log || !log->need_cache_flush)
return;
spin_lock_irq(&log->io_list_lock);
@@ -1115,6 +1138,8 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
return -ENOMEM;
log->rdev = rdev;
+ log->need_cache_flush = (rdev->bdev->bd_disk->queue->flush_flags != 0);
+
log->uuid_checksum = crc32_le(~0, (void *)rdev->mddev->uuid,
sizeof(rdev->mddev->uuid));
--
1.9.1
--
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