dm thin: refactor requeue_io to eliminate spinlock bouncing

Also refactor some other bio_list erroring helpers.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 575e3ed..fb05f6a 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -457,21 +457,32 @@ struct dm_thin_endio_hook {
        struct rb_node rb_node;
 };
 
-static void requeue_bio_list(struct thin_c *tc, struct bio_list *master)
+static void __merge_bio_list(struct bio_list *bios, struct bio_list *master)
+{
+       bio_list_merge(bios, master);
+       bio_list_init(master);
+}
+
+static void error_bio_list(struct bio_list *bios, int error)
 {
        struct bio *bio;
+
+       while ((bio = bio_list_pop(bios)))
+               bio_endio(bio, error);
+}
+
+static void error_thin_bio_list(struct thin_c *tc, struct bio_list *master, int error)
+{
        struct bio_list bios;
        unsigned long flags;
 
        bio_list_init(&bios);
 
        spin_lock_irqsave(&tc->lock, flags);
-       bio_list_merge(&bios, master);
-       bio_list_init(master);
+       __merge_bio_list(&bios, master);
        spin_unlock_irqrestore(&tc->lock, flags);
 
-       while ((bio = bio_list_pop(&bios)))
-               bio_endio(bio, DM_ENDIO_REQUEUE);
+       error_bio_list(&bios, error);
 }
 
 static void requeue_deferred_cells(struct thin_c *tc)
@@ -493,26 +504,18 @@ static void requeue_deferred_cells(struct thin_c *tc)
 
 static void requeue_io(struct thin_c *tc)
 {
-       requeue_bio_list(tc, &tc->deferred_bio_list);
-       requeue_bio_list(tc, &tc->retry_on_resume_list);
-       requeue_deferred_cells(tc);
-}
-
-static void error_thin_retry_list(struct thin_c *tc)
-{
-       struct bio *bio;
-       unsigned long flags;
        struct bio_list bios;
+       unsigned long flags;
 
        bio_list_init(&bios);
 
        spin_lock_irqsave(&tc->lock, flags);
-       bio_list_merge(&bios, &tc->retry_on_resume_list);
-       bio_list_init(&tc->retry_on_resume_list);
+       __merge_bio_list(&bios, &tc->deferred_bio_list);
+       __merge_bio_list(&bios, &tc->retry_on_resume_list);
        spin_unlock_irqrestore(&tc->lock, flags);
 
-       while ((bio = bio_list_pop(&bios)))
-               bio_io_error(bio);
+       error_bio_list(&bios, DM_ENDIO_REQUEUE);
+       requeue_deferred_cells(tc);
 }
 
 static void error_retry_list(struct pool *pool)
@@ -521,7 +524,7 @@ static void error_retry_list(struct pool *pool)
 
        rcu_read_lock();
        list_for_each_entry_rcu(tc, &pool->active_thins, list)
-               error_thin_retry_list(tc);
+               error_thin_bio_list(tc, &tc->retry_on_resume_list, -EIO);
        rcu_read_unlock();
 }
 
@@ -1752,7 +1755,7 @@ static void process_thin_deferred_bios(struct thin_c *tc)
        unsigned count = 0;
 
        if (tc->requeue_mode) {
-               requeue_bio_list(tc, &tc->deferred_bio_list);
+               error_thin_bio_list(tc, &tc->deferred_bio_list, DM_ENDIO_REQUEUE);
                return;
        }