svn commit: r212439 - head/sys/fs/nfs

[Kostik Belousov]

On Sat, Sep 11, 2010 at 08:41:22PM -0400, Rick Macklem wrote:
> > Then, fid_reserved is no more reserved ? Should we rename it ?
> > 
> > Comment for fid_reserved about longword alignment is wrong.
> 
> Well, it's actually more broken than that.
> fid_len - Most file systems set it to the size of their variant
>           of the entire structure, including the Xfid_len field.
>           ZFS sets it to the size of the structure - sizeof(uint16_t)
>           { presumably subtracting out the size if Xfid_len? }.
>           And xfs, well, it does weird stuff with it I can't figure
>           out, but it is definitely not the size of the entire struct.
> 
> As such, exposing fid_len above the VOP_xxx() doesn't make much sense.
> (After my commit yesterday, nothing above the VOP_VPTOFH() uses it.)
> 
> Personally, I'd lean towards a generic struct fid like...
> struct fid {
>        uint8_t fid_data[MAXFIDSZ];
> };
> with MAXFIDSZ increased appropriately, but this will require changes
> to xfs and zfs, since they both set the generic fid_len.
> 
> If you go with...
> struct fid {
>        uint16_t fid_len;
>        uint8_t fid_data[MAXFIDSZ];
> };
> then the hash functions in the two NFS servers need to be changed
> (they assume 32bit alignment of fid_data), but they should be fixed
> anyhow, since they mostly hash to 0 for ZFS at this time. (From what
> I see ZFS file handles looking like.)
> 
> Or, you could just rename fid_reserved to fid_pad and not worry about it.
> 
> Maybe the ZFS folks could decide what they would prefer? rick
Let at least rename the field. And I propose the name like fid_data0
or similar, not the fid_pad, to signify that it is used.
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