pstore/ram: Include ecc_size when calculating ecc_block

Wastes less memory and allows using more memory for ecc than data.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
[jstultz: Tweaked commit subject]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 0306303be372..e5afa222c213 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -187,7 +187,8 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
         prz->ecc_block_size = 128;
         prz->ecc_size = ecc_size;
 
-        ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
+        ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_size,
+                                  prz->ecc_block_size + prz->ecc_size);
         ecc_total = (ecc_blocks + 1) * prz->ecc_size;
         if (ecc_total >= prz->buffer_size) {
                 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",