erofs: correct the remaining shrink objects

commit 9d5a09c6 upstream.

The remaining count should not include successful
shrink attempts.

Fixes: e7e9a307 ("staging: erofs: introduce workstation for decompression")
Cc: <stable@vger.kernel.org> # 4.19+
Link: https://lore.kernel.org/r/20200226081008.86348-1-gaoxiang25@huawei.comReviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/utils.c

@@ -309,7 +309,7 @@ unsigned long erofs_shrink_scan(struct shrinker *shrink,
 		sbi->shrinker_run_no = run_no;
 
 #ifdef CONFIG_EROFS_FS_ZIP
-		freed += erofs_shrink_workstation(sbi, nr, false);
+		freed += erofs_shrink_workstation(sbi, nr - freed, false);
 #endif
 
 		spin_lock(&erofs_sb_list_lock);