On Sat, Sep 06, 2025 at 05:25:11PM -0400, Chuck Lever wrote: > From: Mike Snitzer <snitzer@xxxxxxxxxx> > > Add 'io_cache_read' to NFSD's debugfs interface so that any data > read by NFSD will either be: > - cached using page cache (NFSD_IO_BUFFERED=0) > - cached but removed from the page cache upon completion > (NFSD_IO_DONTCACHE=1). > > io_cache_read may be set by writing to: > /sys/kernel/debug/nfsd/io_cache_read > > Add 'io_cache_write' to NFSD's debugfs interface so that any data > written by NFSD will either be: > - cached using page cache (NFSD_IO_BUFFERED=0) > - cached but removed from the page cache upon completion > (NFSD_IO_DONTCACHE=1). > > io_cache_write may be set by writing to: > /sys/kernel/debug/nfsd/io_cache_write > > The default value for both settings is NFSD_IO_BUFFERED, which is > NFSD's existing behavior for both read and write. Changes to these > settings take immediate effect for all exports and NFS versions. > > Currently only xfs and ext4 implement RWF_DONTCACHE. For file > systems that do not implement RWF_DONTCACHE, NFSD use only buffered > I/O when the io_cache setting is NFSD_IO_DONTCACHE. > > Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> > Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> > --- > fs/nfsd/debugfs.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++ > fs/nfsd/nfsd.h | 9 +++++ > fs/nfsd/vfs.c | 21 +++++++++++ > 3 files changed, 123 insertions(+) > > Changes since v1: > - Corrected patch author > - Break back to NFSD_IO_BUFFERED when exported file system does not > support RWF_DONTCACHE > - Smoke tested NFSD_IO_DONTCACHE with NFSv3,v4.0,v4.1 on xfs and > tmpfs Looks good, thanks. Mike
