[PATCH v6 2/5] zram: reject zero-size dictionary

[Haoqin Huang <haoqinhuang7@gmail.com>]

From: Haoqin Huang <haoqinhuang@tencent.com>

kernel_read_file_from_path() already rejects empty files (i_size <= 0)
and returns -EINVAL, but the current implementation only checks for
sz < 0 without logging any information. Use sz == 0 to reject the
zero-size case and print distinct error messages for each failure type.

Signed-off-by: Haoqin Huang <haoqinhuang@tencent.com>
Signed-off-by: Rongwei Wang <zigiwang@tencent.com>
---
 drivers/block/zram/zram_drv.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index cfa98846ac48..f73e30b61067 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1700,8 +1700,16 @@ static int comp_params_store(struct zram *zram, u32 prio, s32 level,
 						INT_MAX,
 						NULL,
 						READING_POLICY);
-		if (sz < 0)
+		if (sz < 0) {
+			pr_err("failed to load dictionary %s (err=%zd)\n",
+			       dict_path, sz);
+			return sz;
+		}
+		if (sz == 0) {
+			pr_err("failed to load dictionary %s (empty file)\n",
+			       dict_path);
 			return -EINVAL;
+		}
 	}
 
 	zram->params[prio].dict_sz = sz;
-- 
2.43.7