[PATCH v2] xfs: send warning of project quota to userspace via netlink

[Masatake YAMATO]

I'm sorry, mistakenly I sent the same message multiple times.
All the same. so please, review the any one of them.

Masatake YAMATO

> Linux's quota subsystem has an ability to handle
> project quota. This commit just utilizes the ability
> from xfs side.
> 
> dbus-monitor and quota_nld shipped as part of quota-tools can
> be used for testing.
> 
> The testing environment and condition:
> 
>     # cat /etc/projects
>     10:/root/Q/a
>     # grep Q /proc/mounts
>     /dev/loop0 /root/Q xfs rw,relatime,attr2,inode64,prjquota 0 0
>     # ls -l /dev/loop0
>     brw-rw---- 1 root disk 7, 0 Nov 26 10:46 /dev/loop0
> 
> 3 terminals are used for each commands: dd, quota_nld, and dbus-monitor.
> 
> Start quota_nld with terminal 1:
> 
> 	[1]# quota_nld -F
> 
> Start dbus-monitor with terminal 2:
> 
>         [2]# dbus-monitor --system
> 
> Start dd to generate a large file for hitting the quota limit:
> 
>         [3]# dd if=/dev/sda of=/root/Q/a/X
> 
> At the terminal 1, you will see warning messages like:
> 
>    quota_nld: Failed to open tty /dev/tty1 of user 0 to report warning.
> 
> Let's ignore them.  These meaningless messages
> are suppressed by a patch available at
> https://sourceforge.net/p/linuxquota/patches/43/.
> 
> At the terminal 2, you will see following traffic about disk quota
> (newlines are inserted):
> 
>     signal time=1448502680.741715 sender=:1.35 -> \
> 	   destination=(null destination) serial=4 path=/; \
> 	   interface=com.system.quota.warning; member=warning
>        uint32 2
>        uint64 10
>        uint32 6
>        uint32 7
>        uint32 0
>        uint64 0
>     signal time=1448502680.742518 sender=:1.35 -> \
> 	   destination=(null destination) serial=5 path=/; \
> 	   interface=com.system.quota.warning; member=warning
>        uint32 2
>        uint64 10
>        uint32 4
>        uint32 7
>        uint32 0
>        uint64 0
> 
> The 1st "2" means the type of quota: project quota.
> The 2nd "10" means the project id.
> The 3rd "4" and "6" mean "Block hardlimit reached" and
> "Block softlimit reached".
> The 4th "7" means the major number of loop0.
> The 5th "0" means the minor number of loop0.
> 
> Changes in v2:
> 
> 	a couple aesthetic things suggested by Brian Foster <bfoster at redhat.com>.
> 	* rename local vairable for aligning the parameter names,
> 	* move a short line to the end of its previous line.
> 
> Signed-off-by: Masatake YAMATO <yamato at redhat.com>
> ---
>  fs/xfs/xfs_trans_dquot.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/xfs/xfs_trans_dquot.c b/fs/xfs/xfs_trans_dquot.c
> index ce78534..9951701 100644
> --- a/fs/xfs/xfs_trans_dquot.c
> +++ b/fs/xfs/xfs_trans_dquot.c
> @@ -572,12 +572,16 @@ xfs_quota_warn(
>  	struct xfs_dquot	*dqp,
>  	int			type)
>  {
> -	/* no warnings for project quotas - we just return ENOSPC later */
> +	enum quota_type qtype;
> +
>  	if (dqp->dq_flags & XFS_DQ_PROJ)
> -		return;
> -	quota_send_warning(make_kqid(&init_user_ns,
> -				     (dqp->dq_flags & XFS_DQ_USER) ?
> -				     USRQUOTA : GRPQUOTA,
> +		qtype = PRJQUOTA;
> +	else if (dqp->dq_flags & XFS_DQ_USER)
> +		qtype = USRQUOTA;
> +	else
> +		qtype = GRPQUOTA;
> +
> +	quota_send_warning(make_kqid(&init_user_ns, qtype,
>  				     be32_to_cpu(dqp->q_core.d_id)),
>  			   mp->m_super->s_dev, type);
>  }
> -- 
> 2.5.0
>