In a yocto distribution the ntfs file system of a USB key is mounted read-only?

To enable the mount of USB key formatted with file system ntfs I have created the following configuration fragment file:

CONFIG_NTFS_FS=m
# CONFIG_NTFS_DEBUG is not set
CONFIG_NTFS_RW=y

This file sets the parameters CONFIG_NTFS_FS and CONFIG_NTFS_RW used by the kernel build. To compile the kernel I have used the command:

bitbake -C compile virtual/kernel

With this modification of the kernel config my distribution is able to execute the mount of an ntfs USB by the command:

> mount /dev/sda /media/sda

where /dev/sda is the device associated with the USB key, and /media/sda is the mount point. The file system is mounted but read-only. This is showed by the following command:

# mount | grep media
/dev/sda on /media/sda type ntfs (ro,relatime,uid=0,gid=0,fmask=0177,dmask=077,nls=iso8859-1,errors=continue,mft_zone_multiplier=1)

In the fragment file I have set CONFIG_NTFS_RW=y, so why the ntfs file system of a USB key is mounted read-only? ___ **EDIT** If I execute the command dmesg I obtain the following message:

> dmesg
...
(device sda): load_system_files(): Volume is dirty.  Mounting read-only.  Run chkdsk and mount in Windows.

I have followed the info written in the previous message: - I have inserted the USB on a Windows system - The Windows system has executed a scanfix of the USB After that I have execute correctly the mount R/W of the USB on my Linux system:

> mount -t ntfs /dev/sda /media/sda
> mount | grep media
/dev/sda on /media/sda type ntfs (rw,relatime,uid=0,gid=0,fmask=0177,dmask=077,nls=iso8859-1,errors=continue,mft_zone_multiplier=1)

At this point if I try to write on the USB I get the following error:

> touch /media/sda/write_ntfs.txt
touch: cannot touch '/media/sda/write_ntfs.txt': Permission denied

The same if I try to change the permission of a file present on the USB:

> chmod 777 /media/sda/filename.csv
chmod: changing permissions of '/media/sda/filename.csv': Operation not supported

So, despite the output of the command mount, seems that the mount of the USB is yet read-only!