Commit 0b48d422 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-3.3' of git://linux-nfs.org/~bfields/linux 

* 'for-3.3' of git://linux-nfs.org/~bfields/linux: (31 commits)
  nfsd4: nfsd4_create_clid_dir return value is unused
  NFSD: Change name of extended attribute containing junction
  svcrpc: don't revert to SVC_POOL_DEFAULT on nfsd shutdown
  svcrpc: fix double-free on shutdown of nfsd after changing pool mode
  nfsd4: be forgiving in the absence of the recovery directory
  nfsd4: fix spurious 4.1 post-reboot failures
  NFSD: forget_delegations should use list_for_each_entry_safe
  NFSD: Only reinitilize the recall_lru list under the recall lock
  nfsd4: initialize special stateid's at compile time
  NFSd: use network-namespace-aware cache registering routines
  SUNRPC: create svc_xprt in proper network namespace
  svcrpc: update outdated BKL comment
  nfsd41: allow non-reclaim open-by-fh's in 4.1
  svcrpc: avoid memory-corruption on pool shutdown
  svcrpc: destroy server sockets all at once
  svcrpc: make svc_delete_xprt static
  nfsd: Fix oops when parsing a 0 length export
  nfsd4: Use kmemdup rather than duplicating its implementation
  nfsd4: add a separate (lockowner, inode) lookup
  nfsd4: fix CONFIG_NFSD_FAULT_INJECTION compile error
  ...
parents 8e63dd6e 7a6ef8c7

CREDITS

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S: Amsterdam

S: The Netherlands



N: NeilBrown

E: neil@brown.name

P: 4096R/566281B9 1BC6 29EB D390 D870 7B5F  497A 39EC 9EDD 5662 81B9

D: NFSD Maintainer 2000-2007



N: Zach Brown

E: zab@zabbo.net

D: maestro pci sound

Documentation/filesystems/nfs/00-INDEX

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	- this file (nfs-related documentation).

Exporting

	- explanation of how to make filesystems exportable.

fault_injection.txt

	- information for using fault injection on the server

knfsd-stats.txt

	- statistics which the NFS server makes available to user space.

nfs.txt

Documentation/filesystems/nfs/fault_injection.txt

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Fault Injection

===============

Fault injection is a method for forcing errors that may not normally occur, or

may be difficult to reproduce.  Forcing these errors in a controlled environment

can help the developer find and fix bugs before their code is shipped in a

production system.  Injecting an error on the Linux NFS server will allow us to

observe how the client reacts and if it manages to recover its state correctly.



NFSD_FAULT_INJECTION must be selected when configuring the kernel to use this

feature.





Using Fault Injection

=====================

On the client, mount the fault injection server through NFS v4.0+ and do some

work over NFS (open files, take locks, ...).



On the server, mount the debugfs filesystem to <debug_dir> and ls

<debug_dir>/nfsd.  This will show a list of files that will be used for

injecting faults on the NFS server.  As root, write a number n to the file

corresponding to the action you want the server to take.  The server will then

process the first n items it finds.  So if you want to forget 5 locks, echo '5'

to <debug_dir>/nfsd/forget_locks.  A value of 0 will tell the server to forget

all corresponding items.  A log message will be created containing the number

of items forgotten (check dmesg).



Go back to work on the client and check if the client recovered from the error

correctly.





Available Faults

================

forget_clients:

     The NFS server keeps a list of clients that have placed a mount call.  If

     this list is cleared, the server will have no knowledge of who the client

     is, forcing the client to reauthenticate with the server.



forget_openowners:

     The NFS server keeps a list of what files are currently opened and who

     they were opened by.  Clearing this list will force the client to reopen

     its files.



forget_locks:

     The NFS server keeps a list of what files are currently locked in the VFS.

     Clearing this list will force the client to reclaim its locks (files are

     unlocked through the VFS as they are cleared from this list).



forget_delegations:

     A delegation is used to assure the client that a file, or part of a file,

     has not changed since the delegation was awarded.  Clearing this list will

     force the client to reaquire its delegation before accessing the file

     again.



recall_delegations:

     Delegations can be recalled by the server when another client attempts to

     access a file.  This test will notify the client that its delegation has

     been revoked, forcing the client to reaquire the delegation before using

     the file again.





tools/nfs/inject_faults.sh script

=================================

This script has been created to ease the fault injection process.  This script

will detect the mounted debugfs directory and write to the files located there

based on the arguments passed by the user.  For example, running

`inject_faults.sh forget_locks 1` as root will instruct the server to forget

one lock.  Running `inject_faults forget_locks` will instruct the server to

forgetall locks.

MAINTAINERS

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KERNEL NFSD, SUNRPC, AND LOCKD SERVERS

M:	"J. Bruce Fields" <bfields@fieldses.org>

M:	Neil Brown <neilb@suse.de>

L:	linux-nfs@vger.kernel.org

W:	http://nfs.sourceforge.net/

S:	Supported

fs/nfsd/Kconfig

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	  available from http://linux-nfs.org/.



	  If unsure, say N.



config NFSD_FAULT_INJECTION

	bool "NFS server manual fault injection"

	depends on NFSD_V4 && DEBUG_KERNEL

	help

	  This option enables support for manually injecting faults

	  into the NFS server.  This is intended to be used for

	  testing error recovery on the NFS client.



	  If unsure, say N.

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