[patch 035/176] staging: zram: fix data corruption issue

[Greg KH]

2.6.36-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Nitin Gupta <ngupta@xxxxxxxxxx>

commit 5414e557fca545614ceedc3d3496f747457e2e3b upstream.

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@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/staging/zram/zram_drv.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -235,6 +235,7 @@ static int zram_read(struct zram *zram,
 
 		if (zram_test_flag(zram, index, ZRAM_ZERO)) {
 			handle_zero_page(page);
+			index++;
 			continue;
 		}
 
@@ -243,12 +244,14 @@ static int zram_read(struct zram *zram,
 			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;
 		}
 
@@ -324,6 +327,7 @@ static int zram_write(struct zram *zram,
 			mutex_unlock(&zram->lock);
 			zram_stat_inc(&zram->stats.pages_zero);
 			zram_set_flag(zram, index, ZRAM_ZERO);
+			index++;
 			continue;
 		}
 


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