[PATCH] zram: propagate read_from_bdev_async() errors

[Sergey Senozhatsky <senozhatsky@chromium.org>]

When read_from_bdev_async() fails to chain bio, for instance
fails to allocate request or bio, we need to propagate the
error condition so that upper layer is aware of it.  zram
already does that by setting BLK_STS_IOERR ->bi_status,
but only for sync reads.  Change async read path to return
its error status so that async errors are also handled.

Suggested-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 drivers/block/zram/zram_drv.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 63f71371a7e9..b47cb1d99144 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1445,21 +1445,21 @@ static void zram_async_read_endio(struct bio *bio)
 	queue_work(system_highpri_wq, &req->work);
 }
 
-static void read_from_bdev_async(struct zram *zram, struct page *page,
-				 u32 index, unsigned long blk_idx,
-				 struct bio *parent)
+static int read_from_bdev_async(struct zram *zram, struct page *page,
+				u32 index, unsigned long blk_idx,
+				struct bio *parent)
 {
 	struct zram_rb_req *req;
 	struct bio *bio;
 
 	req = kmalloc_obj(*req, GFP_NOIO);
 	if (!req)
-		return;
+		return -ENOMEM;
 
 	bio = bio_alloc(zram->bdev, 1, parent->bi_opf, GFP_NOIO);
 	if (!bio) {
 		kfree(req);
-		return;
+		return -ENOMEM;
 	}
 
 	req->zram = zram;
@@ -1475,6 +1475,8 @@ static void read_from_bdev_async(struct zram *zram, struct page *page,
 	__bio_add_page(bio, page, PAGE_SIZE, 0);
 	bio_inc_remaining(parent);
 	submit_bio(bio);
+
+	return 0;
 }
 
 static void zram_sync_read(struct work_struct *w)
@@ -1523,8 +1525,7 @@ static int read_from_bdev(struct zram *zram, struct page *page, u32 index,
 			return -EIO;
 		return read_from_bdev_sync(zram, page, index, blk_idx);
 	}
-	read_from_bdev_async(zram, page, index, blk_idx, parent);
-	return 0;
+	return read_from_bdev_async(zram, page, index, blk_idx, parent);
 }
 #else
 static inline void reset_bdev(struct zram *zram) {};
-- 
2.53.0.851.ga537e3e6e9-goog