From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Rosenberg Subject: [PATCH v3 2/4] f2fs: Fix root reserved on remount Date: Wed, 29 May 2019 17:49:04 -0700 Message-ID: <20190530004906.261170-3-drosen@google.com> References: <20190530004906.261170-1-drosen@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20190530004906.261170-1-drosen@google.com> Sender: linux-kernel-owner@vger.kernel.org To: Jaegeuk Kim , Chao Yu , Jonathan Corbet , linux-f2fs-devel@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@android.com, Daniel Rosenberg List-Id: linux-f2fs-devel.lists.sourceforge.net On a remount, you can currently set root reserved if it was not previously set. This can cause an underflow if reserved has been set to a very high value, since then root reserved + current reserved could be greater than user_block_count. inc_valid_block_count later subtracts out these values from user_block_count, causing an underflow. Signed-off-by: Daniel Rosenberg --- fs/f2fs/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 912e2619d581b..359fd68509d16 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -213,7 +213,8 @@ void f2fs_msg(struct super_block *sb, const char *level, const char *fmt, ...) static inline void limit_reserve_root(struct f2fs_sb_info *sbi) { - block_t limit = (sbi->user_block_count << 1) / 1000; + block_t limit = min((sbi->user_block_count << 1) / 1000, + sbi->user_block_count - sbi->reserved_blocks); /* limit is 0.2% */ if (test_opt(sbi, RESERVE_ROOT) && -- 2.22.0.rc1.257.g3120a18244-goog