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authorLinus Torvalds <torvalds@linux-foundation.org>2012-10-10 23:52:35 +0900
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-10 23:52:35 +0900
commitdf632d3ce7eacf92ad9b642301c7b53a1d95b8d8 (patch)
tree848c39ed4f7cfdb582bf2e0a0a03147efaa5198d /Documentation/filesystems
parent2474542f64432398f503373f53bdf620491bcfa8 (diff)
parentaf283885b70248268617955a5ea5476647bd556b (diff)
Merge tag 'nfs-for-3.7-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
Pull NFS client updates from Trond Myklebust: "Features include: - Remove CONFIG_EXPERIMENTAL dependency from NFSv4.1 Aside from the issues discussed at the LKS, distros are shipping NFSv4.1 with all the trimmings. - Fix fdatasync()/fsync() for the corner case of a server reboot. - NFSv4 OPEN access fix: finally distinguish correctly between open-for-read and open-for-execute permissions in all situations. - Ensure that the TCP socket is closed when we're in CLOSE_WAIT - More idmapper bugfixes - Lots of pNFS bugfixes and cleanups to remove unnecessary state and make the code easier to read. - In cases where a pNFS read or write fails, allow the client to resume trying layoutgets after two minutes of read/write- through-mds. - More net namespace fixes to the NFSv4 callback code. - More net namespace fixes to the NFSv3 locking code. - More NFSv4 migration preparatory patches. Including patches to detect network trunking in both NFSv4 and NFSv4.1 - pNFS block updates to optimise LAYOUTGET calls." * tag 'nfs-for-3.7-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (113 commits) pnfsblock: cleanup nfs4_blkdev_get NFS41: send real read size in layoutget NFS41: send real write size in layoutget NFS: track direct IO left bytes NFSv4.1: Cleanup ugliness in pnfs_layoutgets_blocked() NFSv4.1: Ensure that the layout sequence id stays 'close' to the current NFSv4.1: Deal with seqid wraparound in the pNFS return-on-close code NFSv4 set open access operation call flag in nfs4_init_opendata_res NFSv4.1: Remove the dependency on CONFIG_EXPERIMENTAL NFSv4 reduce attribute requests for open reclaim NFSv4: nfs4_open_done first must check that GETATTR decoded a file type NFSv4.1: Deal with wraparound when updating the layout "barrier" seqid NFSv4.1: Deal with wraparound issues when updating the layout stateid NFSv4.1: Always set the layout stateid if this is the first layoutget NFSv4.1: Fix another refcount issue in pnfs_find_alloc_layout NFSv4: don't put ACCESS in OPEN compound if O_EXCL NFSv4: don't check MAY_WRITE access bit in OPEN NFS: Set key construction data for the legacy upcall NFSv4.1: don't do two EXCHANGE_IDs on mount NFS: nfs41_walk_client_list(): re-lock before iterating ...
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/nfs/nfs.txt44
1 files changed, 41 insertions, 3 deletions
diff --git a/Documentation/filesystems/nfs/nfs.txt b/Documentation/filesystems/nfs/nfs.txt
index f50f26ce6cd..f2571c8bef7 100644
--- a/Documentation/filesystems/nfs/nfs.txt
+++ b/Documentation/filesystems/nfs/nfs.txt
@@ -12,9 +12,47 @@ and work is in progress on adding support for minor version 1 of the NFSv4
protocol.
The purpose of this document is to provide information on some of the
-upcall interfaces that are used in order to provide the NFS client with
-some of the information that it requires in order to fully comply with
-the NFS spec.
+special features of the NFS client that can be configured by system
+administrators.
+
+
+The nfs4_unique_id parameter
+============================
+
+NFSv4 requires clients to identify themselves to servers with a unique
+string. File open and lock state shared between one client and one server
+is associated with this identity. To support robust NFSv4 state recovery
+and transparent state migration, this identity string must not change
+across client reboots.
+
+Without any other intervention, the Linux client uses a string that contains
+the local system's node name. System administrators, however, often do not
+take care to ensure that node names are fully qualified and do not change
+over the lifetime of a client system. Node names can have other
+administrative requirements that require particular behavior that does not
+work well as part of an nfs_client_id4 string.
+
+The nfs.nfs4_unique_id boot parameter specifies a unique string that can be
+used instead of a system's node name when an NFS client identifies itself to
+a server. Thus, if the system's node name is not unique, or it changes, its
+nfs.nfs4_unique_id stays the same, preventing collision with other clients
+or loss of state during NFS reboot recovery or transparent state migration.
+
+The nfs.nfs4_unique_id string is typically a UUID, though it can contain
+anything that is believed to be unique across all NFS clients. An
+nfs4_unique_id string should be chosen when a client system is installed,
+just as a system's root file system gets a fresh UUID in its label at
+install time.
+
+The string should remain fixed for the lifetime of the client. It can be
+changed safely if care is taken that the client shuts down cleanly and all
+outstanding NFSv4 state has expired, to prevent loss of NFSv4 state.
+
+This string can be stored in an NFS client's grub.conf, or it can be provided
+via a net boot facility such as PXE. It may also be specified as an nfs.ko
+module parameter. Specifying a uniquifier string is not support for NFS
+clients running in containers.
+
The DNS resolver
================