Re: [PATCH 15/16] zram: fix synchronous reads

[Christoph Hellwig <hch@lst.de>]

Meh, turns out this doesn't even compile for PAGE_SIZE > 4096.

Below is the fix, which also removes the #if and instead relies
on compiler dead code elimination.  I wonder if zram should (maybe
optionally) also offer a 512 byte block size, so that we could
also test the smaller than page size I/O path even on x86.

---
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 3af04684c11ebb..c989907301d06e 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -764,7 +764,6 @@ static ssize_t writeback_store(struct device *dev,
 	return ret;
 }
 
-#if PAGE_SIZE != 4096
 struct zram_work {
 	struct work_struct work;
 	struct zram *zram;
@@ -776,7 +775,7 @@ struct zram_work {
 static void zram_sync_read(struct work_struct *work)
 {
 	struct zram_work *zw = container_of(work, struct zram_work, work);
-	struct bio_bvec bv;
+	struct bio_vec bv;
 	struct bio bio;
 
 	bio_init(&bio, zw->zram->bdev, &bv, 1, REQ_OP_READ);
@@ -795,6 +794,9 @@ static int read_from_bdev_sync(struct zram *zram, struct page *page,
 {
 	struct zram_work work;
 
+	if (WARN_ON_ONCE(PAGE_SIZE != 4096))
+		return -EIO;
+
 	work.page = page;
 	work.zram = zram;
 	work.entry = entry;
@@ -806,14 +808,6 @@ static int read_from_bdev_sync(struct zram *zram, struct page *page,
 
 	return work.error;
 }
-#else
-static int read_from_bdev_sync(struct zram *zram, struct page *page,
-				unsigned long entry)
-{
-	WARN_ON(1);
-	return -EIO;
-}
-#endif
 
 static int read_from_bdev(struct zram *zram, struct page *page,
 			unsigned long entry, struct bio *parent)