f2fs: add ioctl to get IO priority hint

This patch adds an ioctl to give a per-file priority hint to attach
REQ_PRIO.

Reviewed-by: Chao Yu <[e-mail]>
Signed-off-by: Jaegeuk Kim <[e-mail]>

fs/f2fs/data.c

···
 static blk_opf_t f2fs_io_flags(struct f2fs_io_info *fio)
 {
 	unsigned int temp_mask = GENMASK(NR_TEMP_TYPE - 1, 0);
+	struct folio *fio_folio = page_folio(fio->page);
 	unsigned int fua_flag, meta_flag, io_flag;
 	blk_opf_t op_flags = 0;
 
···
 		op_flags |= REQ_META;
 	if (BIT(fio->temp) & fua_flag)
 		op_flags |= REQ_FUA;
+
+	if (fio->type == DATA &&
+	    F2FS_I(fio_folio->mapping->host)->ioprio_hint == F2FS_IOPRIO_WRITE)
+		op_flags |= REQ_PRIO;
+
 	return op_flags;
 }
 

fs/f2fs/f2fs.h

···
 
 	/* Use below internally in f2fs*/
 	unsigned long flags[BITS_TO_LONGS(FI_MAX)];	/* use to pass per-file flags */
+	unsigned int ioprio_hint;	/* hint for IO priority */
 	struct f2fs_rwsem i_sem;	/* protect fi info */
 	atomic_t dirty_pages;		/* # of dirty pages */
 	f2fs_hash_t chash;		/* hash value of given file name */

fs/f2fs/file.c

···
 			(u32 __user *)arg);
 }
 
+static int f2fs_ioc_io_prio(struct file *filp, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	__u32 level;
+
+	if (get_user(level, (__u32 __user *)arg))
+		return -EFAULT;
+
+	if (!S_ISREG(inode->i_mode) || level >= F2FS_IOPRIO_MAX)
+		return -EINVAL;
+
+	inode_lock(inode);
+	F2FS_I(inode)->ioprio_hint = level;
+	inode_unlock(inode);
+	return 0;
+}
+
 int f2fs_precache_extents(struct inode *inode)
 {
 	struct f2fs_inode_info *fi = F2FS_I(inode);
···
 		return f2fs_ioc_compress_file(filp);
 	case F2FS_IOC_GET_DEV_ALIAS_FILE:
 		return f2fs_ioc_get_dev_alias_file(filp, arg);
+	case F2FS_IOC_IO_PRIO:
+		return f2fs_ioc_io_prio(filp, arg);
 	default:
 		return -ENOTTY;
 	}
···
 	case F2FS_IOC_DECOMPRESS_FILE:
 	case F2FS_IOC_COMPRESS_FILE:
 	case F2FS_IOC_GET_DEV_ALIAS_FILE:
+	case F2FS_IOC_IO_PRIO:
 		break;
 	default:
 		return -ENOIOCTLCMD;

include/uapi/linux/f2fs.h

···
 #define F2FS_IOC_COMPRESS_FILE		_IO(F2FS_IOCTL_MAGIC, 24)
 #define F2FS_IOC_START_ATOMIC_REPLACE	_IO(F2FS_IOCTL_MAGIC, 25)
 #define F2FS_IOC_GET_DEV_ALIAS_FILE	_IOR(F2FS_IOCTL_MAGIC, 26, __u32)
+#define F2FS_IOC_IO_PRIO		_IOW(F2FS_IOCTL_MAGIC, 27, __u32)
 
 /*
  * should be same as XFS_IOC_GOINGDOWN.
···
 #define F2FS_TRIM_FILE_DISCARD		0x1	/* send discard command */
 #define F2FS_TRIM_FILE_ZEROOUT		0x2	/* zero out */
 #define F2FS_TRIM_FILE_MASK		0x3
+
+/* for F2FS_IOC_IO_PRIO */
+enum {
+	F2FS_IOPRIO_WRITE = 1,	/* high write priority */
+	F2FS_IOPRIO_MAX,
+};
 
 struct f2fs_gc_range {
 	__u32 sync;