NFS buffered write cleanup

[Christoph Hellwig <hch@lst.de>]

Hi all,

this series cleans up the nfs_page handling in the buffer write path.

The first patch was already sent independently but hasn't been picked up
and this included here again.

The last patch fixes a bug where a request could get incorrectly reused.
It would require the flexfiles layout and odd I/O timings, and without
a flexfiles server I can't actually hit it.  I'd appreciate a careful
review of that one.

The series is against Trond's testing branch.

Diffstat:
 fs/nfs/file.c                  |    6 
 fs/nfs/filelayout/filelayout.c |    1 
 fs/nfs/fscache.c               |    2 
 fs/nfs/internal.h              |    8 -
 fs/nfs/pagelist.c              |  117 ---------------
 fs/nfs/pnfs.h                  |   22 --
 fs/nfs/pnfs_nfs.c              |   47 ------
 fs/nfs/read.c                  |    2 
 fs/nfs/write.c                 |  316 ++++++++++++++++++-----------------------
 include/linux/nfs_page.h       |    7 
 10 files changed, 157 insertions(+), 371 deletions(-)