staging: zram: fix data corruption issue

In zram_read() and zram_write() we were not incrementing the
index number and thus were reading/writing values from/to
incorrect sectors on zram disk, resulting in data corruption.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 5415712f01f804bf1ed432034c98e148561324bb..4bd8cbdaee76fe8de24b4d88bf0543314f285410 100644 (file)
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -227,6 +227,7 @@ static int zram_read(struct zram *zram, struct bio *bio)
 
                if (zram_test_flag(zram, index, ZRAM_ZERO)) {
                        handle_zero_page(page);
+                       index++;
                        continue;
                }
 
@@ -235,12 +236,14 @@ static int zram_read(struct zram *zram, struct bio *bio)
                        pr_debug("Read before write: sector=%lu, size=%u",
                                (ulong)(bio->bi_sector), bio->bi_size);
                        /* Do nothing */
+                       index++;
                        continue;
                }
 
                /* Page is stored uncompressed since it's incompressible */
                if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
                        handle_uncompressed_page(zram, page, index);
+                       index++;
                        continue;
                }
 
@@ -320,6 +323,7 @@ static int zram_write(struct zram *zram, struct bio *bio)
                        mutex_unlock(&zram->lock);
                        zram_stat_inc(&zram->stats.pages_zero);
                        zram_set_flag(zram, index, ZRAM_ZERO);
+                       index++;
                        continue;
                }