[PATCH] zram: add comment

[Minchan Kim]

Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 drivers/block/zram/zram_drv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index decca6f161b8..6f1ceb14e64b 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -975,6 +975,14 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
 	err = zram_bvec_rw(zram, &bv, index, offset, rw);
 out_unlock:
 	up_read(&zram->init_lock);
+	/*
+	 * If I/O fails, just return error(ie, non-zero) without
+	 * calling page_endio.
+	 * It causes resubmit the I/O with bio request by upper functions
+	 * of rw_page(e.g., swap_readpage, __swap_writepage) and
+	 * bio->bi_end_io does things to handle the error
+	 * (e.g., SetPageError, set_page_dirty and extra works).
+	 */
 	if (err == 0)
 		page_endio(page, rw, 0);
 	return err;
-- 
2.0.0

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-- 
Kind regards,
Minchan Kim
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