[LTP] [PATCH v3] mm/zram: fix broken testcase

[Caspar Z. <ca...@ca...>]

v2 -> v3: fix a silly potential loop

current zram test is broken:

* At the end of test, error message printed:
    ERROR: Module zram is in use
  this is because the mapped area `s' is not freed yet. This patch unmaps
  it before calling `rmmod zram'.

* Sometimes `if (access() && errno == ENOENT)' doesn't work due to errno
  not correctly captured.

* argument passing to memset() is incorrect.

The fixes to above issues are all integrated into this patch and the
patch is tested by myself.

Signed-off-by: Caspar Zhang <ca...@ca...>
---
 testcases/kernel/mem/zram/zram01.c |   30 ++++++++++++++++++++++--------
 1 files changed, 22 insertions(+), 8 deletions(-)