block: add bio_has_data() to detect whether a bio carries data or not

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 0933a14e641423f523d8ed7a56ef7f2a6b849e5c..9e93c9299479054aa0273ff65b144c6f161b4719 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -445,6 +445,14 @@ static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
        __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 #define bio_kunmap_irq(buf,flags)      __bio_kunmap_irq(buf, flags)
 
+/*
+ * Check whether this bio carries any data or not. A NULL bio is allowed.
+ */
+static inline int bio_has_data(struct bio *bio)
+{
+       return bio && bio->bi_io_vec != NULL;
+}
+
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 
 #define bip_vec_idx(bip, idx)  (&(bip->bip_vec[(idx)]))