ganesha-export-config - Man Page

NFS Ganesha Export Configuration File

Synopsis

/etc/ganesha/ganesha.conf

Description

NFS-Ganesha obtains configuration data from the configuration file:

/etc/ganesha/ganesha.conf

This file lists NFS-Ganesha Export block config options.

Export_defaults {}

These options are all "export permissions" options, and will be repeated in the Export {} and Export { Client {} } blocks.

These options will all be dynamically updateable.

Access_Type(enum, default None)
Possible values:

None, RW, RO, MDONLY, MDONLY_RO

Protocols(enum list, default none)
Possible values:

3, 4, NFS3, NFS4, V3, V4, NFSv3, NFSv4, 9P

Transports(enum list, values [UDP, TCP, RDMA], default [UDP, TCP])

Anonymous_uid(anonid, range INT32_MIN to UINT32_MAX, default -2)

Anonymous_gid(anonid, range INT32_MIN to UINT32_MAX, default -2)

SecType(enum list, default [none, sys])
Possible values:

none, sys, krb5, krb5i, krb5p

PrivilegedPort(bool, default false)

Manage_Gids(bool, default false)

Squash(enum, default root_sqaush)
Possible values:

root, root_squash, rootsquash, rootid, root_id_squash, rootidsquash, all, all_squash, allsquash, all_anomnymous, allanonymous, no_root_squash, none, noidsquash

Each line of defaults above are synonyms

Security_Label(bool, default false)

NFS_Commit(bool, default false)

Delegations(enum, default None)
Possible values:

None, read, write, readwrite, r, w, rw

Attr_Expiration_Time(int32, range -1 to INT32_MAX, default 60)

Export {}

All options below are dynamically changeable with config update unless specified below.

Export_id (required):

An identifier for the export, must be unique and between 0 and 65535. If Export_Id 0 is specified, Pseudo must be the root path (/).

Export_id is not dynamic per se, changing it essentially removes the old export and introduces a new export.

Path (required)

The directory in the exported file system this export is rooted on (may be ignored for some FSALs). It need not be unique if Pseudo and/or Tag are specified.

Note that if it is not unique, and the core option mount_path_pseudo is not set true, a v3 mount using the path will ONLY be able to access the first export configured. To access other exports the Tag option would need to be used.

This option is NOT dynamically updateable since it fundamentally changes the export. To change the path exported, export_id should be changed also.

Pseudo (required v4)

This option specifies the position in the Pseudo Filesystem this export occupies if this is an NFS v4 export. It must be unique. By using different Pseudo options, the same Path may be exported multiple times.

This option is used to place the export within the NFS v4 Pseudo Filesystem. This creates a single name space for NFS v4. Clients may mount the root of the Pseudo Filesystem and navigate to exports. Note that the Path and Tag options are not at all visible to NFS v4 clients.

Export id 0 is automatically created to provide the root and any directories necessary to navigate to exports if there is no other export specified with Pseudo = /;. Note that if an export is specified with Pseudo = /;, it need not be export id 0. Specifying such an export with FSAL { name = PSEUDO; } may be used to create a Pseudo Filesystem with specific options. Such an export may also use other FSALs (though directories to reach exports will ONLY be automatically created on FSAL PSEUDO exports).

This option is dynamically changeable and changing it will move the export within the pseudo filesystem. This may be disruptive to clients. Note that if the mount_path_pseudo NFS_CORE_PARAM option is true, the NFSv3 mount path will also change (that should not be disruptive to clients that have the export mounted).

Tag (no default)

This option allows an alternative access for NFS v3 mounts. The option MUST not have a leading /. Clients may not mount subdirectories (i.e. if Tag = foo, the client may not mount foo/baz). By using different Tag options, the same Path may be exported multiple times.

This option is not dynamically updatable.

MaxRead (64*1024*1024)

The maximum read size on this export

MaxWrite (64*1024*1024)

The maximum write size on this export

PrefRead (64*1024*1024)

The preferred read size on this export. Note that some older nfs client (e.g. libnfs 1.x) would not handle well for large preferred read size. If so, please try to decrease this size (usually less than 1M is suitable for older nfs client).

PrefWrite (64*1024*1024)

The preferred write size on this export. Note that some older nfs client (e.g. libnfs 1.x) would not handle well for large preferred write size. If so, please try to decrease this size (usually less than 1M is suitable for older nfs client).

PrefReaddir (16384)

The preferred readdir size on this export

MaxOffsetWrite (INT64_MAX)

Maximum file offset that may be written Range is 512 to UINT64_MAX

MaxOffsetRead (INT64_MAX)

Maximum file offset that may be read Range is 512 to UINT64_MAX

CLIENT (optional)

See the Export { Client {} } block.

FSAL (required)

See the Export { Fsal {} } block.

The FSAL for an export can not be changed dynamically. In order to change the FSAL, a new export must be created.

At this time, no FSAL actually supports any updatable options.

Export { Client {} }

Take all the "export permissions" options from EXPORT_DEFAULTS. The client lists are dynamically updateable.

These blocks form an ordered "access control list" for the export. If no client block matches for a particular client, then the permissions in the Export {} block will be used.

Even when a CLIENT block matches a client, if a particular export permission is not explicit in that CLIENT block, the permission specified in the EXPORT block will be used, or if not specified there, from the EXPORT_DEFAULTS block, and if not specified there, the permission will default to the default code value noted in the permission option descriptions above.

Note that when the CLIENT blocks are processed on config reload, a new client access list is constructed and atomically swapped in. This allows adding, removing, and re-arranging clients as well as changing the access for any give client.

Clients(client list, empty)

Client list entries can take on one of the following forms: Match any client:

@name       Netgroup name
x.x.x.x/y   IPv4 network address
wildcarded  If the string contains at least one ? or *
            character (and is not simply "*"), the string is
            used to pattern match host names. Note that [] may
            also be used, but the pattern MUST have at least one
            ? or *
hostname    Match a single client (match is by IP address, all
            addresses returned by getaddrinfo will match, the
            getaddrinfo call is made at config parsing time)
IP address  Match a single client

Export { Fsal {} }

NFS-Ganesha supports the following FSALs: Ceph Gluster GPFS PROXY_V3 PROXY_V4 RGW VFS XFS LUSTRE LIzardFS KVSFS

Refer to individual FSAL config file for list of config options.

The FSAL blocks generally are less updatable

Discussion

The EXPORT blocks define the file namespaces that are served by NFS-Ganesha.

In best practice, each underlying filesystem has a single EXPORT defining how that filesystem is to be shared, however, in some cases, it is desirable to sub-divide a filesystem into multiple exports. The danger when this is done is that rogue clients may be able to spoof file handles and access portions of the filesystem not intended to be accessible to that client.

Some FSALs (currently FSAL_VFS, FSAL_GPFS, FSAL_XFS, and FSAL_LUSTRE) are built to support nested filesystems, for example:

/export/fs1 /export/fs1/some/path/fs2

In this case, it is possible to create a single export that exports both filesystems. There is a lot of complexity of what can be done there.

In discussions of filesystems, btrfs filesystems exported by FSAL_VFS may have subvolumes. Starting in NFS-Ganesha V4.0 FSAL_VFS treats these as separate filesystems that are integrated with all the richness of FSAL_VFS exports.

Another significant FSAL from an export point of view is FSAL_PSEUDO. This is used to build glue exports to build the unified NFSv4 name space. This name space may also be used by NFSv3 by setting the NFS_CORE_PARAM option:

mount_path_pseudo = TRUE;

If no FSAL_PSEUDO export is explicitly defined, and there is no EXPORT with:

Pseudo = "/";

NFS-Ganesha will build a FSAL_PSEUDO EXPORT with this Pseudo Path using Export_Id = 0. This automatic EXPORT may be replaced with an explicit EXPORT which need not have Export_Id = 0, it just must have Pseudo = "/" and Protocols = 4.

In building the Pseudo Filesystem, there is a subtle gotcha. Since NFSv4 clients actually moount the root of the Pseudo Filesystem and then use LOOKUP to traverse into the actual directory the sysadmin has mounted from the client, any EXPORTs from "/" to the desired EXPORT MUST have Protocols = 4 specified either in Export_defaults {}, Export {}, or Export { Client {} }. This is to assure that the client is allowed to traverse each EXPORT.

If Mount_Path_Pseudo = TRUE is being used and an export is desired to be NFSv3 only, Protocols = 3 MUST be specified in the Export {} block. If Protocols is not specified in the Export {} block and is only specified in an Export { Client {} } block, then that export will still be mounted in the Pseudo Filesystem but might not be traversable. Thus if the following two filesystems are exported:

/export/fs1 /export/fs1/some/path/fs2

And the EXPORTs look something like this:

EXPORT {

Export_Id = 1; Path = /export/fs1; Peudo = /export/fs1;

FSAL {

Name = VFS;

}

CLIENT {

Clients="*"; Protocols=3;

}

}
EXPORT {

Export_Id = 1; Path = /export/fs1/some/path/fs2; Peudo = /export/fs1/some/path/fs2;

FSAL {

Name = VFS;

}

CLIENT {

Clients="*"; Protocols=3,4;

}

}

NFSv4 clients will not be able to access /export/fs1/some/path/fs2. The correct way to accomplish this is:

EXPORT {

Export_Id = 1; Path = /export/fs1; Peudo = /export/fs1; Protocols=3;

FSAL
{

Name = VFS;

}

}

Note that an Export { Client {} } block is not necessary if the default export permissions are workable.

Note that in order for an EXPORT to be usable with NSFv4 it MUST either have Protocols = 4 specified in the EXPORT block, or the EXPORT block must not have the Protocols option at all such that it defaults to 3,4,9P. Note though that if it is not set and EXPORT_DEFAULTS just has Protocols = 3; then even though the export is mounted in the Pseudo Filesystem, it will not be accessible and the gotcha discussed above may be in play.

Configuration Reload

In addition to the LOG {} configuration, Export {} config is the main configuration that can be updated while NFS-Ganesha is running by issuing a SIGHUP.

This causes all EXPORT and EXPORT_DEFAULTS blocks to be reloaded. NFS-Ganesha V4.0 and later have some significant improvements to this since it was introduced in NFS-Ganesha V2.4.0. V2.8.0 introduced the ability to remove EXPORTs via SIGHUP configuration reload.

Significantly how things work now is:

On SIGHUP all the EXPORT and EXPORT_DEFAULTS blocks are re-read. There are three conditions that may occur:

An export may be added An export may be removed An export may be updated

A note on Export_Id and Path. These are the primary options that define an export. If Export_Id is changed, the change is treated as a remove of the old Export_Id and an addition of the new Export_Id. Path can not be changed without also changing Export_Id. The Tag and Pseudo options that also contribute to the uniqueness of an EXPORT may be changed.

Any removed exports are removed from the internal tables and if they are NFSv4 exports, unmounted from the Pseudo Filesystem, which will then be re-built as if those exports had not been present.

Any new exports are added to the internal tables, and if the export is an NFSv4 export, they are mounted into the Pseudo Filesystem.

Any updated exports will be modified with the least disruption possible. If the Pseduo option is changed, the export is unmounted from the Pseduo Filesystem in it's original location, and re-mounted in it's new location. Other options are updated atomically, though serially, so for a short period of time, the options may be mixed between old and new. In most cases this should not cause problems. Notably though, the CLIENT blocks are processed to form a new access control list and that list is atomically swapped with the old list. If the Protocols for an EXPORT are changed to include or remove NFSv4, the Pseduo Filesystem will also be updated.

Note that there is no pause in operations other than a lock being taken when the client list is being swapped out, however the export permissions are applied to an operation once. Notably for NFSv4, this is on a PUTFH or LOOKUP which changes the Current File Handle. As an example, if a write is in progress, having passed the permission check with the previous export permissions, the write will complete without interruption. If the write is part of an NFSv4 COMPOUND, the other operations in that COMPOUND that operate on the same file handle will also complete with the previous export permissions.

An update of EXPORT_DEFAULTS changes the export options atomically. These options are only used for those options not otherwise set in an Export {} or CLIENT {} block and are applied when export permissions are evaluated when a new file handle is encountered.

The FSAL { Name } may not be changed and FSALs offer limited support for changing any options in the FSAL block. Some FSALs may validate and warn if any options in the FSAL block are changed when such a change is not supported.

See Also

ganesha-config(8) ganesha-rgw-config(8) ganesha-vfs-config(8) ganesha-lustre-config(8) ganesha-xfs-config(8) ganesha-gpfs-config(8) ganesha-9p-config(8) ganesha-proxy-config(8) ganesha-ceph-config(8)

Referenced By

ganesha-ceph-config(8), ganesha-config(8), ganesha-gluster-config(8), ganesha-gpfs-config(8), ganesha-proxy-v3-config(8), ganesha-proxy-v4-config(8), ganesha-rgw-config(8), ganesha-vfs-config(8).

Nov 30, 2022 NFS-Ganesha