f2fs: introduce a new ioctl F2FS_IOC_WRITE_CHECKPOINT

This patch introduce a new ioctl for those users who want to trigger
checkpoint from userspace through ioctl.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -231,6 +231,7 @@ static inline bool __has_cursum_space(struct f2fs_summary_block *sum, int size,
 #define F2FS_IOC_RELEASE_VOLATILE_WRITE	_IO(F2FS_IOCTL_MAGIC, 4)
 #define F2FS_IOC_ABORT_VOLATILE_WRITE	_IO(F2FS_IOCTL_MAGIC, 5)
 #define F2FS_IOC_GARBAGE_COLLECT	_IO(F2FS_IOCTL_MAGIC, 6)
+#define F2FS_IOC_WRITE_CHECKPOINT	_IO(F2FS_IOCTL_MAGIC, 7)
 
 #define F2FS_IOC_SET_ENCRYPTION_POLICY					\
 		_IOR('f', 19, struct f2fs_encryption_policy)

fs/f2fs/file.c

@@ -1639,6 +1639,27 @@ static int f2fs_ioc_gc(struct file *filp, unsigned long arg)
 	return f2fs_gc(sbi, sync);
 }
 
+static int f2fs_ioc_write_checkpoint(struct file *filp, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct cp_control cpc;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (f2fs_readonly(sbi->sb))
+		return -EROFS;
+
+	cpc.reason = __get_cp_reason(sbi);
+
+	mutex_lock(&sbi->gc_mutex);
+	write_checkpoint(sbi, &cpc);
+	mutex_unlock(&sbi->gc_mutex);
+
+	return 0;
+}
+
 long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	switch (cmd) {
@@ -1670,6 +1691,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return f2fs_ioc_get_encryption_pwsalt(filp, arg);
 	case F2FS_IOC_GARBAGE_COLLECT:
 		return f2fs_ioc_gc(filp, arg);
+	case F2FS_IOC_WRITE_CHECKPOINT:
+		return f2fs_ioc_write_checkpoint(filp, arg);
 	default:
 		return -ENOTTY;
 	}