zram: refactor zram_bdev_read

Split the partial read into a separate helper.

Link: https://lkml.kernel.org/r/20230411171459.567614-12-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.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 40ef0a7ce348aebdee20995016fc765046a17bf4..2e985531d8cba883d0abca66f7166d7cdf9b4a48 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1416,33 +1416,33 @@ static int zram_read_page(struct zram *zram, struct page *page, u32 index,
        return ret;
 }
 
-static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
-                         u32 index, int offset, struct bio *bio)
+/*
+ * Use a temporary buffer to decompress the page, as the decompressor
+ * always expects a full page for the output.
+ */
+static int zram_bvec_read_partial(struct zram *zram, struct bio_vec *bvec,
+                                 u32 index, int offset, struct bio *bio)
 {
+       struct page *page = alloc_page(GFP_NOIO);
        int ret;
-       struct page *page;
-
-       page = bvec->bv_page;
-       if (is_partial_io(bvec)) {
-               /* Use a temporary buffer to decompress the page */
-               page = alloc_page(GFP_NOIO);
-               if (!page)
-                       return -ENOMEM;
-       }
-
-       ret = zram_read_page(zram, page, index, bio, is_partial_io(bvec));
-       if (unlikely(ret))
-               goto out;
 
-       if (is_partial_io(bvec))
+       if (!page)
+               return -ENOMEM;
+       ret = zram_read_page(zram, page, index, bio, true);
+       if (likely(!ret))
                memcpy_to_bvec(bvec, page_address(page) + offset);
-out:
-       if (is_partial_io(bvec))
-               __free_page(page);
-
+       __free_page(page);
        return ret;
 }
 
+static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
+                         u32 index, int offset, struct bio *bio)
+{
+       if (is_partial_io(bvec))
+               return zram_bvec_read_partial(zram, bvec, index, offset, bio);
+       return zram_read_page(zram, bvec->bv_page, index, bio, false);
+}
+
 static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
                                u32 index, struct bio *bio)
 {