On Sun, Oct 8, 2017 at 8:45 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
> On Fri, Oct 06, 2017 at 03:36:06PM -0700, Dan Williams wrote:
>> A 'lease_direct' lease requires that the vma have a valid MAP_DIRECT
>> mapping established. For xfs we establish a new lease and then check if
>> the MAP_DIRECT mapping has been broken. We want to be sure that the
>> process will receive notification that the MAP_DIRECT mapping is being
>> torn down so it knows why other code paths are throwing failures.
>>
>> For example in the RDMA/ibverbs case we want ibv_reg_mr() to fail if the
>> MAP_DIRECT mapping is invalid or in the process of being invalidated.
>>
>> Cc: Jan Kara <jack@xxxxxxx>
>> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
>> Cc: Christoph Hellwig <hch@xxxxxx>
>> Cc: Dave Chinner <david@xxxxxxxxxxxxx>
>> Cc: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
>> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
>> Cc: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
>> Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
>> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>> ---
>> fs/xfs/xfs_file.c | 28 ++++++++++++++++++++++++++++
>> 1 file changed, 28 insertions(+)
>>
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index e35518600e28..823b65f17429 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -1166,6 +1166,33 @@ xfs_filemap_direct_close(
>> put_map_direct_vma(vma->vm_private_data);
>> }
>>
>> +static struct lease_direct *
>> +xfs_filemap_direct_lease(
>> + struct vm_area_struct *vma,
>> + void (*break_fn)(void *),
>> + void *owner)
>> +{
>> + struct lease_direct *ld;
>> +
>> + ld = map_direct_lease(vma, break_fn, owner);
>> +
>> + if (IS_ERR(ld))
>> + return ld;
>> +
>> + /*
>> + * We now have an established lease while the base MAP_DIRECT
>> + * lease was not broken. So, we know that the "lease holder" will
>> + * receive a SIGIO notification when the lease is broken and
>> + * take any necessary cleanup actions.
>> + */
>> + if (!is_map_direct_broken(vma->vm_private_data))
>> + return ld;
>> +
>> + map_direct_lease_destroy(ld);
>> +
>> + return ERR_PTR(-ENXIO);
>
> What's any of this got to do with XFS? Shouldn't it be in generic
> code, and called generic_filemap_direct_lease()?
True, I can move this to generic code. The filesystem is in charge of
where it wants to store the 'struct map_direct_state' context, but for
generic_filemap_direct_lease() it can just assume that it is stored in
->vm_private_data. I'll add comments to this effect on the new
routine.
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