f2fs: add F2FS_IOC_SET_COMPRESS_OPTION ioctl

Added a new F2FS_IOC_SET_COMPRESS_OPTION ioctl to change file
compression option of a file.

struct f2fs_comp_option {
    u8 algorithm;         => compression algorithm
                          => 0:lzo, 1:lz4, 2:zstd, 3:lzorle
    u8 log_cluster_size;  => log scale cluster size
                          => 2 ~ 8
};

struct f2fs_comp_option option;

option.algorithm = 1;
option.log_cluster_size = 7;

ioctl(fd, F2FS_IOC_SET_COMPRESS_OPTION, &option);
Signed-off-by: Daeho Jeong <daehojeong@google.com>
[Chao Yu: remove f2fs_is_compress_algorithm_valid()]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -3972,6 +3972,57 @@ static int f2fs_ioc_get_compress_option(struct file *filp, unsigned long arg)
 	return 0;
 }
 
+static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct f2fs_comp_option option;
+	int ret = 0;
+
+	if (!f2fs_sb_has_compression(sbi))
+		return -EOPNOTSUPP;
+
+	if (!(filp->f_mode & FMODE_WRITE))
+		return -EBADF;
+
+	if (copy_from_user(&option, (struct f2fs_comp_option __user *)arg,
+				sizeof(option)))
+		return -EFAULT;
+
+	if (!f2fs_compressed_file(inode) ||
+			option.log_cluster_size < MIN_COMPRESS_LOG_SIZE ||
+			option.log_cluster_size > MAX_COMPRESS_LOG_SIZE ||
+			option.algorithm >= COMPRESS_MAX)
+		return -EINVAL;
+
+	file_start_write(filp);
+	inode_lock(inode);
+
+	if (f2fs_is_mmap_file(inode) || get_dirty_pages(inode)) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (inode->i_size != 0) {
+		ret = -EFBIG;
+		goto out;
+	}
+
+	F2FS_I(inode)->i_compress_algorithm = option.algorithm;
+	F2FS_I(inode)->i_log_cluster_size = option.log_cluster_size;
+	F2FS_I(inode)->i_cluster_size = 1 << option.log_cluster_size;
+	f2fs_mark_inode_dirty_sync(inode, true);
+
+	if (!f2fs_is_compress_backend_ready(inode))
+		f2fs_warn(sbi, "compression algorithm is successfully set, "
+			"but current kernel doesn't support this algorithm.");
+out:
+	inode_unlock(inode);
+	file_end_write(filp);
+
+	return ret;
+}
+
 long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
@@ -4062,6 +4113,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return f2fs_sec_trim_file(filp, arg);
 	case F2FS_IOC_GET_COMPRESS_OPTION:
 		return f2fs_ioc_get_compress_option(filp, arg);
+	case F2FS_IOC_SET_COMPRESS_OPTION:
+		return f2fs_ioc_set_compress_option(filp, arg);
 	default:
 		return -ENOTTY;
 	}
@@ -4233,6 +4286,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case F2FS_IOC_RESERVE_COMPRESS_BLOCKS:
 	case F2FS_IOC_SEC_TRIM_FILE:
 	case F2FS_IOC_GET_COMPRESS_OPTION:
+	case F2FS_IOC_SET_COMPRESS_OPTION:
 		break;
 	default:
 		return -ENOIOCTLCMD;

include/uapi/linux/f2fs.h

@@ -38,6 +38,8 @@
 						struct f2fs_sectrim_range)
 #define F2FS_IOC_GET_COMPRESS_OPTION	_IOR(F2FS_IOCTL_MAGIC, 21,	\
 						struct f2fs_comp_option)
+#define F2FS_IOC_SET_COMPRESS_OPTION	_IOW(F2FS_IOCTL_MAGIC, 22,	\
+						struct f2fs_comp_option)
 
 /*
  * should be same as XFS_IOC_GOINGDOWN.