dm: bio list helpers

More bio_list helper functions for new targets (including dm-delay and
dm-loop) to manipulate lists of bios.

Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Bryn Reeves <breeves@redhat.com>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/md/dm-bio-list.h b/drivers/md/dm-bio-list.h
index da4349649f7f..c6be88826fae 100644
--- a/drivers/md/dm-bio-list.h
+++ b/drivers/md/dm-bio-list.h
@@ -8,17 +8,43 @@
 #define DM_BIO_LIST_H
 
 #include <linux/bio.h>
+#include <linux/prefetch.h>
 
 struct bio_list {
         struct bio *head;
         struct bio *tail;
 };
 
+static inline int bio_list_empty(const struct bio_list *bl)
+{
+        return bl->head == NULL;
+}
+
+#define BIO_LIST_INIT { .head = NULL, .tail = NULL }
+
+#define BIO_LIST(bl) \
+        struct bio_list bl = BIO_LIST_INIT
+
 static inline void bio_list_init(struct bio_list *bl)
 {
         bl->head = bl->tail = NULL;
 }
 
+#define bio_list_for_each(bio, bl) \
+        for (bio = (bl)->head; bio && ({ prefetch(bio->bi_next); 1; }); \
+             bio = bio->bi_next)
+
+static inline unsigned bio_list_size(const struct bio_list *bl)
+{
+        unsigned sz = 0;
+        struct bio *bio;
+
+        bio_list_for_each(bio, bl)
+                sz++;
+
+        return sz;
+}
+
 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 {
         bio->bi_next = NULL;