zram: refactor zram_bdev_write

Split the read/modify/write case into a separate helper.

Link: https://lkml.kernel.org/r/20230411171459.567614-14-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index cbcfb5c..1a7fe75 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1568,33 +1568,33 @@ out:
        return ret;
 }
 
-static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
-                               u32 index, int offset, struct bio *bio)
+/*
+ * This is a partial IO. Read the full page before writing the changes.
+ */
+static int zram_bvec_write_partial(struct zram *zram, struct bio_vec *bvec,
+                                  u32 index, int offset, struct bio *bio)
 {
-       struct page *page = bvec->bv_page;
+       struct page *page = alloc_page(GFP_NOIO);
        int ret;
 
-       if (is_partial_io(bvec)) {
-               /*
-                * This is a partial IO. We need to read the full page
-                * before to write the changes.
-                */
-               page = alloc_page(GFP_NOIO);
-               if (!page)
-                       return -ENOMEM;
-
-               ret = zram_read_page(zram, page, index, bio, true);
-               if (ret)
-                       goto out;
+       if (!page)
+               return -ENOMEM;
 
+       ret = zram_read_page(zram, page, index, bio, true);
+       if (!ret) {
                memcpy_from_bvec(page_address(page) + offset, bvec);
+               ret = zram_write_page(zram, page, index);
        }
+       __free_page(page);
+       return ret;
+}
 
-       ret = zram_write_page(zram, page, index);
-out:
+static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
+                          u32 index, int offset, struct bio *bio)
+{
        if (is_partial_io(bvec))
-               __free_page(page);
-       return ret;
+               return zram_bvec_write_partial(zram, bvec, index, offset, bio);
+       return zram_write_page(zram, bvec->bv_page, index);
 }
 
 #ifdef CONFIG_ZRAM_MULTI_COMP