From: Christoph Hellwig <hch@infradead.org>
Subject: nfs_file_fsync question
Date: Sat, 26 Sep 2009 13:18:51 -0400
Message-ID: <20090926171851.GA16056@infradead.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
To: linux-nfs@vger.kernel.org
Sender: linux-nfs-owner@vger.kernel.org

Can anyone explain what nfs_do_fsync/nfs_wb_all is trying to do?

We use it for two cases:  either implementing ->fsync or the O_SYNC
implementation in ->aio_write/->splice_write.

But vfs_fsync_range which is used both by the fsync implementation and
called from generic_file_aio_write / generic_file_splice_write alread
y writes out all data and handles errors from it, so ->fsync does not
need to bother with data at all.  nfs_wb_all seems like a
re-implmenetation of the generic page flushing helpers in filemap.c
and not actually touch metadata.  So this code seems useless for the
fsync and O_SYNC cases and only useful for the error catching.  Which
we already do slightly different at VFS-level.  Any reasons to keep
all this cruft around instead of properly integrating it with the
VFS-level error reporting?