knfsd: exportfs: add exportfs.h header

currently the export_operation structure and helpers related to it are in
fs.h.  fs.h is already far too large and there are very few places needing the
export bits, so split them off into a separate header.

[[email protected]: fix cifs build]
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Neil Brown <[email protected]>
Cc: Steven French <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
20 files changed