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nfsd(7) | Miscellaneous Information Manual | nfsd(7) |
NAME¶
nfsd - special filesystem for controlling Linux NFS serverSYNPOSIS¶
mount -t nfsd nfsd /proc/fs/nfsdDESCRIPTION¶
The nfsd filesystem is a special filesystem which provides access to the Linux NFS server. The filesystem consists of a single directory which contains a number of files. These files are actually gateways into the NFS server. Writing to them can affect the server. Reading from them can provide information about the server. This file system is only available in Linux 2.6 and later series kernels (and in the later parts of the 2.5 development series leading up to 2.6). This man page does not apply to 2.4 and earlier. As well as this filesystem, there are a collection of files in the procfs filesystem (normally mounted at /proc) which are used to control the NFS server. This manual page describes all of these files. The exportfs and mountd programs (part of the nfs-utils package) expect to find this filesystem mounted at /proc/fs/nfsd or /proc/fs/nfs. If it is not mounted, they will fall-back on 2.4 style functionality. This involves accessing the NFS server via a systemcall. This systemcall is scheduled to be removed after the 2.6 kernel series.DETAILS¶
The three files in the nfsd filesystem are:- exports
- This file contains a list of filesystems that are currently
exported and clients that each filesystem is exported to, together with a
list of export options for that client/filesystem pair. This is similar to
the /proc/fs/nfs/exports file in 2.4. One difference is that a
client doesn't necessarily correspond to just one host. It can respond to
a large collection of hosts that are being treated identically.
- threads
- This file represents the number of nfsd thread
currently running. Reading it will show the number of threads. Writing an
ASCII decimal number will cause the number of threads to be changed
(increased or decreased as necessary) to achieve that number.
- filehandle
- This is a somewhat unusual file in that what is read from
it depends on what was just written to it. It provides a transactional
interface where a program can open the file, write a request, and read a
response. If two separate programs open, write, and read at the same time,
their requests will not be mixed up.
- auth.domain
- This cache maps the name of a client (or domain) to an
internal data structure. The only access that is possible is to flush the
cache.
- auth.unix.ip
- This cache contains a mapping from IP address to the name
of the authentication domain that the ipaddress should be treated as part
of.
- nfsd.export
- This cache contains a mapping from directory and domain to
export options.
- nfsd.fh
- This cache contains a mapping from domain and a filesystem
identifier to a directory. The filesystem identifier is stored in the
filehandles and consists of a number indicating the type of identifier and
a number of hex bytes indicating the content of the identifier.
- flush
- When a number of seconds since epoch (1 Jan 1970) is
written to this file, all entries in the cache that were last updated
before that file become invalidated and will be flushed out. Writing 1
will flush everything. This is the only file that will always be present.
- content
- This file, if present, contains a textual representation of
ever entry in the cache, one per line. If an entry is still in the cache
(because it is actively being used) but has expired or is otherwise
invalid, it will be presented as a comment (with a leading hash
character).
- channel
- This file, if present, acts a channel for request from the
kernel-based nfs server to be passed to a user-space program for handling.
/proc/sys/sunrpc/nfs_debug
They control tracing for the NFS client, the NFS server, the Network Lock Manager (lockd) and the underlying RPC layer respectively. Decimal numbers can be read from or written to these files. Each number represents a bit-pattern where bits that are set cause certain classes of tracing to be enabled. Consult the kernel header files to find out what number correspond to what tracing.
SEE ALSO¶
nfsd(8), rpc.nfsd(8), exports(5), nfsstat(8), mountd(8) exportfs(8).AUTHOR¶
NeilBrown3 July 2003 |