f2fs: fix to avoid potential race on sbi->unusable_block_count access/update

Use sbi.stat_lock to protect sbi->unusable_block_count accesss/udpate, in
order to avoid potential race on it.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index fe075aa12893..7ddf0d3cbece 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1226,10 +1226,13 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
         buf->f_blocks = total_count - start_count;
         buf->f_bfree = user_block_count - valid_user_blocks(sbi) -
                                                 sbi->current_reserved_blocks;
+
+        spin_lock(&sbi->stat_lock);
         if (unlikely(buf->f_bfree <= sbi->unusable_block_count))
                 buf->f_bfree = 0;
         else
                 buf->f_bfree -= sbi->unusable_block_count;
+        spin_unlock(&sbi->stat_lock);
 
         if (buf->f_bfree > F2FS_OPTION(sbi).root_reserved_blocks)
                 buf->f_bavail = buf->f_bfree -
@@ -1508,7 +1511,10 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
         if (err)
                 goto out_unlock;
 
+        spin_lock(&sbi->stat_lock);
         sbi->unusable_block_count = 0;
+        spin_unlock(&sbi->stat_lock);
+
 out_unlock:
         mutex_unlock(&sbi->gc_mutex);
 restore_flag: