>From: girish chandrashekara <girish_c_99@xxxxxxxxx>
>Hi,
> Iam working on dmapi support in VFS layer of linux
>to make it generic for underlying file systems. In the
>process I went through your source code
>for dmapi support in XFS(2.4.0-test5 kernel), I need
>some clarifications (correct me if Iam wrongly
>understood)
I'm absolutely positive that I must be misunderstanding what you
are asking for, but here goes...
>(1)Data events are triggered by the caller(through
>xfs_ioctls, xfs_dm_fcntl) except create(truncate
>event). How XFS manages (trigger implicitly-initiated
>by kernel)to send data event to DM application incase
>of read,write and mmap by user application on the
>managed region
DM_EVENT_READ comes from XFS this way:
xfs_read->xfs_dm_send_data_event->dm_send_data_event
In Irix XFS, and Linux XFS, we support just one managed region per file.
Mmap is not working yet.
>(2)Nospace event is also triggered through xfs_ioctl
>when filesystem runs out of space. How XFS triggers
>nospace event implicitly, when filesystem runs out of
>space
DM_EVENT_NOSPACE comes in one of two ways:
xfs_alloc_file_space->dm_send_namesp_event
xfs_write->dm_send_namesp_event
Dean
|