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author | Bryan Schumaker <bjschuma@netapp.com> | 2010-09-29 15:41:49 -0400 |
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committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2010-10-07 18:48:49 -0400 |
commit | 955a857e062642cd3ebe1dc7bb38c0f85d8f8f17 (patch) | |
tree | f95fc349c245c4a0a3f6f8fcc5bf02f36a756134 /Documentation | |
parent | aa510da5bfe1dfe263215fd0e05dac96e738a782 (diff) | |
download | kernel_samsung_aries-955a857e062642cd3ebe1dc7bb38c0f85d8f8f17.zip kernel_samsung_aries-955a857e062642cd3ebe1dc7bb38c0f85d8f8f17.tar.gz kernel_samsung_aries-955a857e062642cd3ebe1dc7bb38c0f85d8f8f17.tar.bz2 |
NFS: new idmapper
This patch creates a new idmapper system that uses the request-key function to
place a call into userspace to map user and group ids to names. The old
idmapper was single threaded, which prevented more than one request from running
at a single time. This means that a user would have to wait for an upcall to
finish before accessing a cached result.
The upcall result is stored on a keyring of type id_resolver. See the file
Documentation/filesystems/nfs/idmapper.txt for instructions.
Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
[Trond: fix up the return value of nfs_idmap_lookup_name and clean up code]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/filesystems/nfs/00-INDEX | 2 | ||||
-rw-r--r-- | Documentation/filesystems/nfs/idmapper.txt | 67 |
2 files changed, 69 insertions, 0 deletions
diff --git a/Documentation/filesystems/nfs/00-INDEX b/Documentation/filesystems/nfs/00-INDEX index 2f68cd6..3225a56 100644 --- a/Documentation/filesystems/nfs/00-INDEX +++ b/Documentation/filesystems/nfs/00-INDEX @@ -14,3 +14,5 @@ nfsroot.txt - short guide on setting up a diskless box with NFS root filesystem. rpc-cache.txt - introduction to the caching mechanisms in the sunrpc layer. +idmapper.txt + - information for configuring request-keys to be used by idmapper diff --git a/Documentation/filesystems/nfs/idmapper.txt b/Documentation/filesystems/nfs/idmapper.txt new file mode 100644 index 0000000..c385204 --- /dev/null +++ b/Documentation/filesystems/nfs/idmapper.txt @@ -0,0 +1,67 @@ + +========= +ID Mapper +========= +Id mapper is used by NFS to translate user and group ids into names, and to +translate user and group names into ids. Part of this translation involves +performing an upcall to userspace to request the information. Id mapper will +user request-key to perform this upcall and cache the result. The program +/usr/sbin/nfs.upcall should be called by request-key, and will perform the +translation and initialize a key with the resulting information. + + NFS_USE_NEW_IDMAPPER must be selected when configuring the kernel to use this + feature. + +=========== +Configuring +=========== +The file /etc/request-key.conf will need to be modified so /sbin/request-key can +direct the upcall. The following line should be added: + +#OP TYPE DESCRIPTION CALLOUT INFO PROGRAM ARG1 ARG2 ARG3 ... +#====== ======= =============== =============== =============================== +create id_resolver * * /usr/sbin/nfs.upcall %k %d 600 + +This will direct all id_resolver requests to the program /usr/sbin/nfs.upcall. +The last parameter, 600, defines how many seconds into the future the key will +expire. This parameter is optional for /usr/sbin/nfs.upcall. When the timeout +is not specified, nfs.upcall will default to 600 seconds. + +id mapper uses for key descriptions: + uid: Find the UID for the given user + gid: Find the GID for the given group + user: Find the user name for the given UID + group: Find the group name for the given GID + +You can handle any of these individually, rather than using the generic upcall +program. If you would like to use your own program for a uid lookup then you +would edit your request-key.conf so it look similar to this: + +#OP TYPE DESCRIPTION CALLOUT INFO PROGRAM ARG1 ARG2 ARG3 ... +#====== ======= =============== =============== =============================== +create id_resolver uid:* * /some/other/program %k %d 600 +create id_resolver * * /usr/sbin/nfs.upcall %k %d 600 + +Notice that the new line was added above the line for the generic program. +request-key will find the first matching line and corresponding program. In +this case, /some/other/program will handle all uid lookups and +/usr/sbin/nfs.upcall will handle gid, user, and group lookups. + +See <file:Documentation/keys-request-keys.txt> for more information about the +request-key function. + + +========== +nfs.upcall +========== +nfs.upcall is designed to be called by request-key, and should not be run "by +hand". This program takes two arguments, a serialized key and a key +description. The serialized key is first converted into a key_serial_t, and +then passed as an argument to keyctl_instantiate (both are part of keyutils.h). + +The actual lookups are performed by functions found in nfsidmap.h. nfs.upcall +determines the correct function to call by looking at the first part of the +description string. For example, a uid lookup description will appear as +"uid:user@domain". + +nfs.upcall will return 0 if the key was instantiated, and non-zero otherwise. |