On Feb 4, 2008, at 7:18 PM, Trond Myklebust wrote:
> On Mon, 2008-02-04 at 19:04 -0500, Chuck Lever wrote:
>> Refresh the help text for Kconfig items related to the NFS
>> client. Remove
>> obsolete URLs, and make the language consistent among the options.
>>
>> Also move the ROOT_NFS config option next to the options related
>> to the NFS
>> client.
>>
>> Signed-off-by: Chuck Lever <[email protected]>
>> ---
>>
>> fs/Kconfig | 136 +++++++++++++++++++++++++++++
>> +------------------------------
>> 1 files changed, 69 insertions(+), 67 deletions(-)
>>
>> diff --git a/fs/Kconfig b/fs/Kconfig
>> index 987b5d7..5c7f6ee 100644
>> --- a/fs/Kconfig
>> +++ b/fs/Kconfig
>> @@ -1517,10 +1517,6 @@ config UFS_FS
>> The recently released UFS2 variant (used in FreeBSD
>> 5.x) is
>> READ-ONLY supported.
>>
>> - If you only intend to mount files from some other Unix over the
>> - network using NFS, you don't need the UFS file system support
>> (but
>> - you need NFS file system support obviously).
>> -
>> Note that this option is generally not needed for floppies,
>> since a
>> good portable way to transport files and directories between
>> unixes
>> (and even other operating systems) is given by the tar program
>> ("man
>> @@ -1560,6 +1556,7 @@ menuconfig NETWORK_FILESYSTEMS
>> Say Y here to get to see options for network filesystems and
>> filesystem-related networking code, such as NFS daemon and
>> RPCSEC security modules.
>> +
>> This option alone does not add any kernel code.
>>
>> If you say N, all options in this submenu will be skipped and
>> @@ -1574,44 +1571,35 @@ config NFS_FS
>> select SUNRPC
>> select NFS_ACL_SUPPORT if NFS_V3_ACL
>> help
>> - If you are connected to some other (usually local) Unix computer
>> - (using SLIP, PLIP, PPP or Ethernet) and want to mount files
>> residing
>> - on that computer (the NFS server) using the Network File Sharing
>> - protocol, say Y. "Mounting files" means that the client can
>> access
>> - the files with usual UNIX commands as if they were sitting on the
>> - client's hard disk. For this to work, the server must run the
>> - programs nfsd and mountd (but does not need to have NFS file
>> system
>> - support enabled in its kernel). NFS is explained in the Network
>> - Administrator's Guide, available from
>> - <http://www.tldp.org/docs.html#guide>, on its man page: "man
>> - nfs", and in the NFS-HOWTO.
>> -
>> - A superior but less widely used alternative to NFS is provided by
>> - the Coda file system; see "Coda file system support" below.
>> + Say Y here if you want to access files residing on other
>> computers
>> + using the internet standard Network File System protocol. To
>
> Tsk, tsk.... NFS isn't an internet standard (yet!).
Well, I used lower case. :-)
How about "proposed internet standard" or "de-facto internet
standard" ? We could say "Sun Network File System" but that's just
so antique.
>> + compile this file system support as a module, choose M here: the
>> + module will be called nfs.
>>
>> - If you say Y here, you should have said Y to TCP/IP networking
>> also.
>> - This option would enlarge your kernel by about 27 KB.
>> + To mount file systems exported by NFS servers, you also need to
>> + install the user space mount.nfs command which can be found in
>> + the Linux nfs-utils package, available from http://linux-
>> nfs.org/.
>> + Information about using the mount command is available in the
>> + mount(8) man page. More detail about the Linux NFS client
>> + implementation is available via the nfs(5) man page.
>>
>> - To compile this file system support as a module, choose M
>> here: the
>> - module will be called nfs.
>> + Below you can select which versions of the NFS protocol are
>> + available in the kernel to mount NFS servers. Support for NFS
>> + version 2 (RFC 1094) is always available when NFS_FS is selected.
>>
>> - If you are configuring a diskless machine which will mount its
>> root
>> - file system over NFS at boot time, say Y here and to "Kernel
>> - level IP autoconfiguration" above and to "Root file system on
>> NFS"
>> - below. You cannot compile this driver as a module in this case.
>> - There are two packages designed for booting diskless machines
>> over
>> - the net: netboot, available from
>> - <http://ftp1.sourceforge.net/netboot/>, and Etherboot,
>> - available from <http://ftp1.sourceforge.net/etherboot/>.
>> + To configure a system which mounts its root file system via
>> NFS at
>> + boot time, say Y here, select "Kernel level IP autoconfiguration"
>> + in the NETWORK menu, and select "Root file system on NFS" below.
>> + You cannot compile this driver as a module in this case.
>>
>> - If you don't know what all this is about, say N.
>> + If unsure, say N.
>>
>> config NFS_V3
>> bool "Provide NFSv3 client support"
>> depends on NFS_FS
>> help
>> - Say Y here if you want your NFS client to be able to speak
>> version
>> - 3 of the NFS protocol.
>> + This option enables support for version 3 of the NFS protocol
>> + (RFC 1813) in the kernel's NFS client.
>>
>> If unsure, say Y.
>>
>> @@ -1619,9 +1607,21 @@ config NFS_V3_ACL
>> bool "Provide client support for the NFSv3 ACL protocol extension"
>> depends on NFS_V3
>> help
>> - Implement the NFSv3 ACL protocol extension for manipulating POSIX
>> - Access Control Lists. The server should also be compiled with
>> - the NFSv3 ACL protocol extension; see the CONFIG_NFSD_V3_ACL
>> option.
>> + Some NFS servers support an auxiliary NFSv3 ACL protocol that
>> + Sun added to Solaris but never became an official part of the
>> + NFS version 3 protocol. This nonstandard side-band protocol
>> + allows applications on NFS clients to manipulate POSIX Access
>> + Control Lists on files residing on NFS servers. NFS servers
>> + enforce ACLs on local files whether this protocol is available
>> + or not.
>> +
>> + Say Y here if your NFS server supports the Solaris NFSv3 ACL
>> + protocol and you want your NFS client to allow applications to
>> + access and modify ACLs on files on the server.
>> +
>> + Some NFS servers don't support the Solaris NFSv3 ACL protocol.
> ^^^^ Most?
Fixed.
>> + You can say N here or specify the "noacl" mount option to prevent
>> + your NFS client from trying to use the NFSv3 ACL protocol.
>>
>> If unsure, say N.
>>
>> @@ -1630,38 +1630,54 @@ config NFS_V4
>> depends on NFS_FS && EXPERIMENTAL
>> select RPCSEC_GSS_KRB5
>> help
>> - Say Y here if you want your NFS client to be able to speak the
>> newer
>> - version 4 of the NFS protocol.
>> + This option enables support for version 4 of the NFS protocol
>> + (RFC 3530) in the kernel's NFS client.
>>
>> - Note: Requires auxiliary userspace daemons which may be found on
>> - http://www.citi.umich.edu/projects/nfsv4/
>> + To mount NFS servers using NFSv4, you also need to install user
>> + space programs which can be found in the Linux nfs-utils package,
>> + available from http://linux-nfs.org/.
>>
>> If unsure, say N.
>>
>> config NFS_DIRECTIO
>> bool "Allow direct I/O on NFS files"
>> depends on NFS_FS
>> + default N
>
> Why? Isn't O_DIRECT pretty much a standard feature that is enabled in
> most distros at this time?
> IMO we should rather be aiming to phase out NFS_DIRECTIO.
Using a build option that defaults "off" was your idea, all these
many years ago, as was the language in the help text about how
dangerous uncached I/O is.
I would be happy to provide a patch for 2.6.25 that simply excises
CONFIG_NFS_DIRECTIO and leaves the NFS direct I/O engine always built
in.
>> help
>> - This option enables applications to perform uncached I/O on files
>> - in NFS file systems using the O_DIRECT open() flag. When
>> O_DIRECT
>> - is set for a file, its data is not cached in the system's page
>> - cache. Data is moved to and from user-level application buffers
>> - directly. Unlike local disk-based file systems, NFS O_DIRECT has
>> - no alignment restrictions.
>> + This option enables support for uncached I/O on files accessed
>> + via an NFS mount point. Applications request direct I/O by
>> + setting the O_DIRECT flag when opening a file.
>> +
>> + When direct I/O is requested, the NFS client moves data to and
>> + from user-level application buffers directly to NFS servers.
>> + Direct I/O on NFS files does not suffer from any I/O or buffer
>> + alignment restrictions, as does direct I/O on files that reside
>> + in local file systems.
>> +
>> + For details, see the open(2) man page.
>>
>> Unless your program is designed to use O_DIRECT properly, you are
>> - much better off allowing the NFS client to manage data caching
>> for
>> - you. Misusing O_DIRECT can cause poor server performance or
>> network
>> - storms. This kernel build option defaults OFF to avoid exposing
>> + better off allowing the NFS client to manage data caching for
>> you.
>> + Misusing O_DIRECT can cause poor server performance or network
>> + storms. This kernel build option defaults to N to avoid exposing
>> system administrators unwittingly to a potentially hazardous
>> feature.
>>
>> - For more details on NFS O_DIRECT, see fs/nfs/direct.c.
>> -
>> - If unsure, say N. This reduces the size of the NFS client, and
>> - causes open() to return EINVAL if a file residing in NFS is
>> + If unsure, say N. This reduces the size of the kernel NFS
>> client,
>> + and causes open(2) to return EINVAL if a file residing in NFS is
>> opened with the O_DIRECT flag.
>>
>> +config ROOT_NFS
>> + bool "Root file system on NFS"
>> + depends on NFS_FS=y && IP_PNP
>> + help
>> + If you want your system to mount its root file system via NFS,
>> say
>> + Y here. This is common practice for managing systems without
>> + local permanent storage. Read <file:Documentation/nfsroot.txt>
>> + for details.
>> +
>> + Most people say N here.
>> +
>> config NFSD
>> tristate "NFS server support"
>> depends on INET
>> @@ -1738,20 +1754,6 @@ config NFSD_TCP
>> TCP connections usually perform better than the default UDP when
>> the network is lossy or congested. If unsure, say Y.
>>
>> -config ROOT_NFS
>> - bool "Root file system on NFS"
>> - depends on NFS_FS=y && IP_PNP
>> - help
>> - If you want your Linux box to mount its whole root file system
>> (the
>> - one containing the directory /) from some other computer over the
>> - net via NFS (presumably because your box doesn't have a hard
>> disk),
>> - say Y. Read <file:Documentation/nfsroot.txt> for details. It is
>> - likely that in this case, you also want to say Y to "Kernel
>> level IP
>> - autoconfiguration" so that your box can discover its network
>> address
>> - at boot time.
>> -
>> - Most people say N here.
>> -
>> config LOCKD
>> tristate
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com