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>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 5415712f01f8..4bd8cbdaee76 100644
--- 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;
                 }