block: Add submit_bio_wait(), remove from md

Random cleanup - this code was duplicated and it's not really specific
to md.

Also added the ability to return the actual error code.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/fs/bio.c b/fs/bio.c
index f1b4c1651089..4ce24ee5dcd0 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -752,6 +752,42 @@ int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
 }
 EXPORT_SYMBOL(bio_add_page);
 
+struct submit_bio_ret {
+        struct completion event;
+        int error;
+};
+
+static void submit_bio_wait_endio(struct bio *bio, int error)
+{
+        struct submit_bio_ret *ret = bio->bi_private;
+
+        ret->error = error;
+        complete(&ret->event);
+}
+
+/**
+ * submit_bio_wait - submit a bio, and wait until it completes
+ * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
+ * @bio: The &struct bio which describes the I/O
+ *
+ * Simple wrapper around submit_bio(). Returns 0 on success, or the error from
+ * bio_endio() on failure.
+ */
+int submit_bio_wait(int rw, struct bio *bio)
+{
+        struct submit_bio_ret ret;
+
+        rw |= REQ_SYNC;
+        init_completion(&ret.event);
+        bio->bi_private = &ret;
+        bio->bi_end_io = submit_bio_wait_endio;
+        submit_bio(rw, bio);
+        wait_for_completion(&ret.event);
+
+        return ret.error;
+}
+EXPORT_SYMBOL(submit_bio_wait);
+
 /**
  * bio_advance - increment/complete a bio by some number of bytes
  * @bio:        bio to advance