On Fri, Sep 05, 2025 at 10:55:09AM -0400, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
Aside from attribution, which I suspect you didn't intend to switch
these changes from being attributed to me, this looks good (one small
nit below).
> 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.
>
> If NFSD_IO_DONTCACHE is specified, all exported filesystems must
> implement FOP_DONTCACHE, otherwise IO flagged with RWF_DONTCACHE
> will fail with -EOPNOTSUPP.
>
> 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 | 19 ++++++++++
> 3 files changed, 121 insertions(+)
>
> Changes from Mike's v9:
> - Squashed the "io controls" patches together
> - Removed NFSD_IO_DIRECT for the moment
> - Addressed a few more checkpatch.pl nits
>
> This gives a cleaner platform on which to build the direct I/O code
> paths, and does not expose partially implemented I/O modes to users.
>
> diff --git a/fs/nfsd/debugfs.c b/fs/nfsd/debugfs.c
> index 84b0c8b559dc..2b1bb716b608 100644
> --- a/fs/nfsd/debugfs.c
> +++ b/fs/nfsd/debugfs.c
> @@ -44,4 +131,10 @@ void nfsd_debugfs_init(void)
>
> debugfs_create_file("disable-splice-read", S_IWUSR | S_IRUGO,
> nfsd_top_dir, NULL, &nfsd_dsr_fops);
> +
> + debugfs_create_file("io_cache_read", 0644, nfsd_top_dir, NULL,
> + &nfsd_io_cache_read_fops);
> +
> + debugfs_create_file("io_cache_write", 0644, nfsd_top_dir, NULL,
> + &nfsd_io_cache_write_fops);
> }
Relative to checkpatch warnings, this ^ code is what I'm aware of.
For consistency I stuck with "S_IWUSR | S_IRUG", whereas you honored
checkpatch's suggestion to use 0644.
Maybe update disable-splice-read to also use 0644 too? But your call!
Thanks,
Mike
