block: Introduce new bio_split()

[linux-2.6-block.git] / include / linux / bio.h

diff --git a/include/linux/bio.h b/include/linux/bio.h
index aa67af0b31ac14856059ed32eb472b83fa8f99f5..19e31b2f5b2c0f1910acc08dc8a52b420cb87915 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -321,6 +321,28 @@ extern struct bio_pair *bio_pair_split(struct bio *bi, int first_sectors);
 extern void bio_pair_release(struct bio_pair *dbio);
 extern void bio_trim(struct bio *bio, int offset, int size);
 
+extern struct bio *bio_split(struct bio *bio, int sectors,
+                            gfp_t gfp, struct bio_set *bs);
+
+/**
+ * bio_next_split - get next @sectors from a bio, splitting if necessary
+ * @bio:       bio to split
+ * @sectors:   number of sectors to split from the front of @bio
+ * @gfp:       gfp mask
+ * @bs:                bio set to allocate from
+ *
+ * Returns a bio representing the next @sectors of @bio - if the bio is smaller
+ * than @sectors, returns the original bio unchanged.
+ */
+static inline struct bio *bio_next_split(struct bio *bio, int sectors,
+                                        gfp_t gfp, struct bio_set *bs)
+{
+       if (sectors >= bio_sectors(bio))
+               return bio;
+
+       return bio_split(bio, sectors, gfp, bs);
+}
+
 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 extern void bioset_free(struct bio_set *);
 extern mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries);