f2fs: Fix the race condition of resize flag between resizefs

Because the set/clear SBI_IS_RESIZEFS flag not between any locks,
In the following case:
  thread1			thread2
   ->ioctl(resizefs)
    ->set RESIZEFS flag		 ->ioctl(resizefs)
    ...                   	  ->set RESIZEFS flag
    ->clear RESIZEFS flag
    				  ->resizefs stream
				    # No RESIZEFS flag in the stream

Also before freeze_super, the resizefs not started, we should not set
the SBI_IS_RESIZEFS flag.

So move the set/clear SBI_IS_RESIZEFS flag between the cp_mutex and
gc_lock.

Fixes: b4b10061 ("f2fs: refactor resize_fs to avoid meta updates in progress")
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/gc.c

@@ -2134,8 +2134,6 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
 	if (err)
 		return err;
 
-	set_sbi_flag(sbi, SBI_IS_RESIZEFS);
-
 	freeze_super(sbi->sb);
 	f2fs_down_write(&sbi->gc_lock);
 	f2fs_down_write(&sbi->cp_global_sem);
@@ -2151,6 +2149,7 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
 	if (err)
 		goto out_err;
 
+	set_sbi_flag(sbi, SBI_IS_RESIZEFS);
 	err = free_segment_range(sbi, secs, false);
 	if (err)
 		goto recover_out;
@@ -2174,6 +2173,7 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
 		f2fs_commit_super(sbi, false);
 	}
 recover_out:
+	clear_sbi_flag(sbi, SBI_IS_RESIZEFS);
 	if (err) {
 		set_sbi_flag(sbi, SBI_NEED_FSCK);
 		f2fs_err(sbi, "resize_fs failed, should run fsck to repair!");
@@ -2186,6 +2186,5 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
 	f2fs_up_write(&sbi->cp_global_sem);
 	f2fs_up_write(&sbi->gc_lock);
 	thaw_super(sbi->sb);
-	clear_sbi_flag(sbi, SBI_IS_RESIZEFS);
 	return err;
 }