Commit Graph

93 Commits

Author SHA1 Message Date
Trond Myklebust
d527e5c15d NFSv4.1: Do not call pnfs_return_layout() from an rpciod context
Move the call to pnfs_return_layout() to the read and write rpc_release()
callbacks, so that it gets called from nfsiod, which is a more appropriate
context.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-10-15 10:49:43 -04:00
Peng Tao
6296556f0b NFS41: send real write size in layoutget
For buffer write, block layout client scan inode mapping to find
next hole and use offset-to-hole as layoutget length. Object
layout client uses offset-to-isize as layoutget length.

For direct write, both block layout and object layout use dreq->bytes_left.

Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-10-08 19:32:22 -04:00
Trond Myklebust
e5929f3cff NFSv4.1: Remove the NFS_LAYOUT_RETURNED state
It serves no purpose that the test for whether or not we have valid
layout segments doesn't already serve.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:17 -04:00
Trond Myklebust
8006bfba36 NFSv4.1: Get rid of the NFS_LAYOUT_DESTROYED state
We already have a mechanism for blocking LAYOUTGET by means of the
plh_block_lgets counter. The only "service" that NFS_LAYOUT_DESTROYED
provides at this point is to block layoutget once the layout segment
list is empty, which basically means that you have to wait until
the pnfs_layout_hdr is destroyed before you can do pNFS on that file
again.

This patch enables the reuse of the pnfs_layout_hdr if the layout
segment list is empty.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:16 -04:00
Trond Myklebust
965938b83b NFSv4.1: Get rid of pNFS layout state "NFS_LAYOUT_INVALID"
In all cases where we set NFS_LAYOUT_INVALID, we also set NFS_LAYOUT_DESTROYED.
Furthermore, in all cases where we test for NFS_LAYOUT_INVALID, we should
also be testing for NFS_LAYOUT_DESTROYED, since the latter means that
we hold no valid layout segments.
Ergo the two are redundant.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:12 -04:00
Trond Myklebust
7fdab069b7 NFSv4.1: Fix a race in the pNFS return-on-close code
If we sleep after dropping the inode->i_lock, then we are no longer
atomic with respect to the rpc_wake_up() call in pnfs_layout_remove_lseg().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:11 -04:00
Trond Myklebust
1dfed2737d NFSv4.1: pNFS data servers may be temporarily offline
In cases where the pNFS data server is just temporarily out of service,
we want to mark it as such, and then try again later. Typically that will
be in cases of network connection errors etc.
This patch allows us to mark the devices as being "unavailable" for such
transient errors, and will make them available for retries after a
2 minute timeout period.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:09 -04:00
Trond Myklebust
25c7533357 NFSv4.1: Retry pNFS after a 2 minute timeout
If we had to fall back to read/write through MDS, then assume that we should
retry pNFS after a suitable timeout period.
The following patch sets a timeout of 2 minutes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:09 -04:00
Trond Myklebust
b9e028fd89 NFSv4.1: Add helpers for setting/reading the I/O fail bit
...and make them local to the pnfs.c file.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:09 -04:00
Trond Myklebust
9369a431bc NFSv4.1: Cleanup; add "pnfs_" prefix to put_lseg() and get_lseg()
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:07 -04:00
Trond Myklebust
70c3bd2bdf NFSv4.1: Cleanup; add "pnfs_" prefix to get_layout_hdr() and put_layout_hdr()
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:07 -04:00
Trond Myklebust
49a85061b0 NFSv4.1: Cleanup add a "pnfs_" prefix to mark_matching_lsegs_invalid
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:06 -04:00
Trond Myklebust
a0b0a6e39b NFS: Clean up the pNFS layoutget interface
Ensure that we do return errors from nfs4_proc_layoutget() and that we
don't mark the layout as having failed if the error was due to a
signal or resource problem on the client side.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-09-28 16:03:06 -04:00
Idan Kedar
21d1f58aed pnfs: nfs4_proc_layoutget returns void
since the only user of nfs4_proc_layoutget is send_layoutget, which
ignores its return value, there is no reason to return any value.

Signed-off-by: Idan Kedar <idank@tonian.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-08-02 17:39:06 -04:00
Idan Kedar
8554116e17 pnfs: defer release of pages in layoutget
we have encountered a bug whereby reading a lot of files (copying
fedora's /bin) from a pNFS mount and hitting Ctrl+C in the middle caused
a general protection fault in xdr_shrink_bufhead. this function is
called when decoding the response from LAYOUTGET. the decoding is done
by a worker thread, and the caller of LAYOUTGET waits for the worker
thread to complete.

hitting Ctrl+C caused the synchronous wait to end and the next thing the
caller does is to free the pages, so when the worker thread calls
xdr_shrink_bufhead, the pages are gone. therefore, the cleanup of these
pages has been moved to nfs4_layoutget_release.

Signed-off-by: Idan Kedar <idank@tonian.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-08-02 17:38:54 -04:00
Andy Adamson
366d50521c NFSv4.1 mark layout when already returned
When the file layout driver is fencing a DS, _pnfs_return_layout can be
called mulitple times per inode due to in-flight i/o referencing lsegs on it's
plh_segs list.

Remember that LAYOUTRETURN has been called, and do not call it again.
Allow LAYOUTRETURNs after a subsequent LAYOUTGET.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-07-16 14:37:25 -04:00
Bryan Schumaker
57208fa7e5 NFS: Create an write_pageio_init() function
pNFS needs to select a write function based on the layout driver
currently in use, so I let each NFS version decide how to best handle
initializing writes.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-06-29 11:46:46 -04:00
Bryan Schumaker
1abb50886a NFS: Create an read_pageio_init() function
pNFS needs to select a read function based on the layout driver
currently in use, so I let each NFS version decide how to best handle
initializing reads.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-06-29 11:46:46 -04:00
Fred Isaman
fb47ddc9d5 NFS4: Fix open bug when pnfs module blacklisted
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-06-07 13:44:24 -04:00
Andy Adamson
82be417aa3 NFSv4.1 cache mdsthreshold values on OPEN
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-05-24 16:15:48 -04:00
Andy Adamson
041245c88a NFSv4.1 resend LAYOUTGET on data server invalid layout errors
The "invalid layout" class of errors is handled by destroying the layout and
getting a new layout from the server.  Currently, the layout must be
destroyed before a new layout can be obtained.

This means that all references (e.g.lsegs) to the "to be destroyed" layout
header must be dropped before it can be destroyed. This in turn means waiting
for all in flight RPC's using the old layout as well as draining the data
server session slot table wait queue.

Set the NFS_LAYOUT_INVALID flag to redirect I/O to the MDS while waiting for
the old layout to be destroyed.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-05-19 17:55:33 -04:00
Andy Adamson
e7dd79af01 NFSv4.1: mark deviceid invalid on filelayout DS connection errors
This prevents the use of any layout for i/o that references the deviceid.
I/O is redirected through the MDS.

Redirect the unhandled failed I/O to the MDS without marking either the
layout or the deviceid invalid.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-05-19 17:54:20 -04:00
Bryan Schumaker
b58fee2189 NFS: pnfs_pageio_init_read() and init_write() need an extra argument
This is only when CONFIG_NFS_V4_1 isn't enabled.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Acked-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-04-30 14:06:46 -04:00
Fred Isaman
1763da1234 NFS: rewrite directio write to use async coalesce code
This also has the advantage that it allows directio to use pnfs.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-04-27 14:10:39 -04:00
Fred Isaman
ea2cf2282b NFS: create struct nfs_commit_info
It is COMMIT that is handled the most differently between
the paged and direct paths.  Create a structure that encapsulates
everything either path needs to know about the commit state.

We could use void to hide some of the layout driver stuff, but
Trond suggests pulling it out to ensure type checking, given the
huge changes being made, and the fact that it doesn't interfere
with other drivers.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-04-27 14:10:38 -04:00
Fred Isaman
061ae2edb7 NFS: create completion structure to pass into page_init functions
Factors out the code that will need to change when directio
starts using these code paths.  This will allow directio to use
the generic pagein and flush routines

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-04-27 14:10:38 -04:00
Trond Myklebust
6f00866ddd NFS: Fix more NFS debug related build warnings
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-03-21 09:31:44 -04:00
Trond Myklebust
3b3be88d67 NFS: Use cond_resched_lock() to reduce latencies in the commit scans
Ensure that we conditionally drop the inode->i_lock when it is safe
to do so in the commit loops.
We do so after locking the nfs_page, but before removing it from the
commit list. We can then use list_safe_reset_next to recover the loop
after the lock is retaken.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-03-20 13:08:26 -04:00
Trond Myklebust
8dd3775889 NFSv4.1: Clean ups and bugfixes for the pNFS read/writeback/commit code
Move more pnfs-isms out of the generic commit code.

Bugfixes:

- filelayout_scan_commit_lists doesn't need to get/put the lseg.
  In fact since it is run under the inode->i_lock, the lseg_put()
  can deadlock.

- Ensure that we distinguish between what needs to be done for
  commit-to-data server and what needs to be done for commit-to-MDS
  using the new flag PG_COMMIT_TO_DS. Otherwise we may end up calling
  put_lseg() on a bucket for a struct nfs_page that got written
  through the MDS.

- Fix a case where we were using list_del() on an nfs_page->wb_list
  instead of list_del_init().

- filelayout_initiate_commit needs to call filelayout_commit_release
  on error instead of the mds_ops->rpc_release(). Otherwise it won't
  clear the commit lock.

Cleanups:

- Let the files layout manage the commit lists for the pNFS case.
  Don't expose stuff like pnfs_choose_commit_list, and the fact
  that the commit buckets hold references to the layout segment
  in common code.

- Cast out the put_lseg() calls for the struct nfs_read/write_data->lseg
  into the pNFS layer from whence they came.

- Let the pNFS layer manage the NFS_INO_PNFS_COMMIT bit.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Fred Isaman <iisaman@netapp.com>
2012-03-17 11:09:33 -04:00
Fred Isaman
d6d6dc7cdf NFS: remove nfs_inode radix tree
The radix tree is only being used to compile lists of reqs needing commit.
It is simpler to just put the reqs directly into a list.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-03-10 17:14:10 -05:00
Trond Myklebust
7df529af5f NFSv4.1: Don't call nfs4_deviceid_purge_client() unless we're NFSv4.1
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-02-26 17:34:22 -05:00
Boaz Harrosh
fe0fe83585 pnfs-obj: Must return layout on IO error
As mandated by the standard. In case of an IO error, a pNFS
objects layout driver must return it's layout. This is because
all device errors are reported to the server as part of the
layout return buffer.

This is implemented the same way PNFS_LAYOUTRET_ON_SETATTR
is done, through a bit flag on the pnfs_layoutdriver_type->flags
member. The flag is set by the layout driver that wants a
layout_return preformed at pnfs_ld_{write,read}_done in case
of an error.
(Though I have not defined a wrapper like pnfs_ld_layoutret_on_setattr
 because this code is never called outside of pnfs.c and pnfs IO
 paths)

Without this patch 3.[0-2] Kernels leak memory and have an annoying
WARN_ON after every IO error utilizing the pnfs-obj driver.

[This patch is for 3.2 Kernel. 3.1/0 Kernels need a different patch]
CC: Stable Tree <stable@kernel.org>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-01-06 08:55:33 -05:00
Peng Tao
9b7eecdcfe pnfs: recoalesce when ld read pagelist fails
For pnfs pagelist read failure, we need to pg_recoalesce and resend IO to
mds.

Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Cc: stable@kernel.org [3.0]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-10-18 09:08:14 -07:00
Peng Tao
8ce160c5ef pnfs: recoalesce when ld write pagelist fails
For pnfs pagelist write failure, we need to pg_recoalesce and resend IO to
mds.

Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Cc: stable@kernel.org [3.0]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-10-18 09:08:13 -07:00
Peng Tao
1b0ae06877 pnfs: make _set_lo_fail generic
file layout and block layout both use it to set mark layout io failure
bit. So make it generic.

Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Cc: stable@kernel.org [3.0]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-10-18 09:08:13 -07:00
Trond Myklebust
a00ed25cce NFS: Re-enable compilation of nfs with !CONFIG_NFS_V4 || !CONFIG_NFS_V4_1
Fix two recently introduced compile problems:

Fix a typo in fs/nfs/pnfs.h

Move the pnfs_blksize declaration outside the CONFIG_NFS_V4 section in
struct nfs_server.

Reported-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-31 14:27:04 -10:00
Fred Isaman
2f9fd18260 pnfsblock: call and parse getdevicelist
Call GETDEVICELIST during mount, then call and parse GETDEVICEINFO
for each device returned.

[pnfsblock: get rid of deprecated xdr macros]
Signed-off-by: Jim Rees <rees@umich.edu>
[pnfsblock: fix pnfs_deviceid references]
Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
[pnfsblock: fix print format warnings for sector_t and size_t]
[pnfs-block: #include <linux/vmalloc.h>]
[pnfsblock: no PNFS_NFS_SERVER]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[pnfsblock: fix bug determining size of striped volume]
[pnfsblock: fix oops when using multiple devices]
Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
[pnfsblock: get rid of vmap and deviceid->area structure]
Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-31 12:18:16 -04:00
Andy Adamson
db29c08909 pnfs: cleanup_layoutcommit
This gives layout driver a chance to cleanup structures they put in at
encode_layoutcommit.

Signed-off-by: Andy Adamson <andros@netapp.com>
[fixup layout header pointer for layoutcommit]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
[rm inode and pnfs_layout_hdr args from cleanup_layoutcommit()]
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-31 12:18:15 -04:00
Benny Halevy
738fd0f360 pnfs: add set-clear layoutdriver interface
To allow layout driver to issue getdevicelist at mount time, and clean up
at umount time.

[fixup non NFS_V4_1 set_pnfs_layoutdriver definition]
[pnfs: pass mntfh down the init_pnfs path]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-31 12:18:15 -04:00
Andy Adamson
7f11d8d38d pnfs: GETDEVICELIST
The block driver uses GETDEVICELIST

Signed-off-by: Andy Adamson <andros@netapp.com>
[pass struct nfs_server * to getdevicelist]
[get machince creds for getdevicelist]
[fix getdevicelist decode sizing]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-31 12:18:15 -04:00
Peng Tao
a9bae5666d pnfs: let layoutcommit handle a list of lseg
There can be multiple lseg per file, so layoutcommit should be
able to handle it.

[Needed in v3.0]
CC: Stable Tree <stable@kernel.org>
Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-31 12:18:15 -04:00
Peng Tao
9fa4075878 pnfs: save layoutcommit cred at layout header init
No need to save it for every lseg.
No need to save it at every pnfs_set_layoutcommit.

[Needed in v3.0]
CC: Stable Tree <stable@kernel.org>
Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-31 12:18:14 -04:00
Peng Tao
acff588053 pnfs: save layoutcommit lwb at layout header
No need to save it for every lseg.

[Needed in v3.0]
CC: Stable Tree <stable@kernel.org>
Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-31 12:18:14 -04:00
Trond Myklebust
dce81290ee NFS: Move the pnfs write code into pnfs.c
...and ensure that we recoalese to take into account differences in
differences in block sizes when falling back to write through the MDS.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-15 09:12:22 -04:00
Trond Myklebust
493292ddc7 NFS: Move the pnfs read code into pnfs.c
...and ensure that we recoalese to take into account differences in
block sizes when falling back to read through the MDS.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-15 09:12:21 -04:00
Andy Adamson
c47abcf8ff NFSv4.1: do not use deviceids after MDS clientid invalidation
Mark all deviceids established under an expired MDS clientid as invalid.
Stop all new i/o through DS and send through the MDS.
Don't use any new LAYOUTGETs that use the invalid deviceid. Purge all layouts
established under the expired MDS clientid.
Remove the MDS clientid deviceid and data servers reference

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-12 13:40:29 -04:00
Andy Adamson
7c24d9489f NFSv4.1: File layout only supports whole file layouts
Ask for whole file layouts. Until support for layout segments is fully
supported in the file layout code, discard non-whole file layouts.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-12 13:40:28 -04:00
Trond Myklebust
47cb498e93 NFSv4.1: Clean ups for the device id cache
The fact that the global device id cache holds a reference to the
nfs4_deviceid_node until it is invisible to rcu lookups implies that
we can always assume that the reference count is non-zero in
_find_get_deviceid.

Also clean up nfs4_put_deviceid_node and the removal of the device id
from the cache.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-12 13:40:28 -04:00
Trond Myklebust
d8007d4dd6 NFSv4.1: Add an initialisation callback for pNFS
Ensure that we always get a layout before setting up the i/o request.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-12 13:40:28 -04:00
Trond Myklebust
1751c3638f NFS: Cleanup of the nfs_pageio code in preparation for a pnfs bugfix
We need to ensure that the layouts are set up before we can decide to
coalesce requests. To do so, we want to further split up the struct
nfs_pageio_descriptor operations into an initialisation callback, a
coalescing test callback, and a 'do i/o' callback.

This patch cleans up the existing callback methods before adding the
'initialisation' callback.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-12 13:40:28 -04:00