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>

3 files changed, 14 insertions, 1 deletions

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 805a33088e82..ed70b68b2b38 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1536,7 +1536,11 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
         clear_sbi_flag(sbi, SBI_IS_DIRTY);
         clear_sbi_flag(sbi, SBI_NEED_CP);
         clear_sbi_flag(sbi, SBI_QUOTA_SKIP_FLUSH);
+
+        spin_lock(&sbi->stat_lock);
         sbi->unusable_block_count = 0;
+        spin_unlock(&sbi->stat_lock);
+
         __set_cp_next_pack(sbi);
 
         /*
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8388d2abacb5..8dee063c833f 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2169,8 +2169,11 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
                          * before, we must track that to know how much space we
                          * really have.
                          */
-                        if (f2fs_test_bit(offset, se->ckpt_valid_map))
+                        if (f2fs_test_bit(offset, se->ckpt_valid_map)) {
+                                spin_lock(&sbi->stat_lock);
                                 sbi->unusable_block_count++;
+                                spin_unlock(&sbi->stat_lock);
+                        }
                 }
 
                 if (f2fs_test_and_clear_bit(offset, se->discard_map))
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: