From RFC 7530 Section 16.34.5:
o The server has not recorded an unconfirmed { v, x, c, *, * } and
has recorded a confirmed { v, x, c, *, s }. If the principals of
the record and of SETCLIENTID_CONFIRM do not match, the server
returns NFS4ERR_CLID_INUSE without removing any relevant leased
client state, and without changing recorded callback and
callback_ident values for client { x }.
The current code intends to do what the spec describes above but
it forgot to set 'old' to NULL resulting to the confirmed client
to be expired.
Fixes: 2b63482185 ("nfsd: fix clid_inuse on mount with security change")
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Bruce Fields <bfields@fieldses.org>
In my testing, we're sometimes hitting the request->fl_flags & FL_EXISTS
case in posix_lock_inode, presumably just by random luck since we're not
actually initializing fl_flags here.
This probably didn't matter before commit 7f024fcd5c ("Keep read and
write fds with each nlm_file") since we wouldn't previously unlock
unless we knew there were locks.
But now it causes lockd to give up on removing more locks.
We could just initialize fl_flags, but really it seems dubious to be
calling vfs_lock_file with random values in some of the fields.
Fixes: 7f024fcd5c ("Keep read and write fds with each nlm_file")
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
[ cel: fixed checkpatch.pl nit ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
I thought I was iterating over the array when actually the iteration is
over the values contained in the array?
Ugh, keep it simple.
Symptoms were a null deference in vfs_lock_file() when an NFSv3 client
that previously held a lock came back up and sent a notify.
Reported-by: Jonathan Woithe <jwoithe@just42.net>
Fixes: 7f024fcd5c ("Keep read and write fds with each nlm_file")
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Avoid potentially hazardous memory copying and the needless use of
"%pIS" -- in the kernel, an RPC service listener is always bound to
ANYADDR. Having the network namespace is helpful when recording
errors, though.
Fixes: a0469f46fa ("SUNRPC: Replace dprintk call sites in TCP state change callouts")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
While testing, I got an unexpected KASAN splat:
Jan 08 13:50:27 oracle-102.nfsv4.dev kernel: BUG: KASAN: stack-out-of-bounds in trace_event_raw_event_svc_xprt_create_err+0x190/0x210 [sunrpc]
Jan 08 13:50:27 oracle-102.nfsv4.dev kernel: Read of size 28 at addr ffffc9000008f728 by task mount.nfs/4628
The memcpy() in the TP_fast_assign section of this trace point
copies the size of the destination buffer in order that the buffer
won't be overrun.
In other similar trace points, the source buffer for this memcpy is
a "struct sockaddr_storage" so the actual length of the source
buffer is always long enough to prevent the memcpy from reading
uninitialized or unallocated memory.
However, for this trace point, the source buffer can be as small as
a "struct sockaddr_in". For AF_INET sockaddrs, the memcpy() reads
memory that follows the source buffer, which is not always valid
memory.
To avoid copying past the end of the passed-in sockaddr, make the
source address's length available to the memcpy(). It would be a
little nicer if the tracing infrastructure was more friendly about
storing socket addresses that are not AF_INET, but I could not find
a way to make printk("%pIS") work with a dynamic array.
Reported-by: KASAN
Fixes: 4b8f380e46 ("SUNRPC: Tracepoint to record errors in svc_xpo_create()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
RTM says "If the special ONE stateid is passed to
nfs4_preprocess_stateid_op(), it returns status=0 but does not set
*cstid. nfsd4_copy_notify() depends on stid being set if status=0, and
thus can crash if the client sends the right COPY_NOTIFY RPC."
RFC 7862 says "The cna_src_stateid MUST refer to either open or locking
states provided earlier by the server. If it is invalid, then the
operation MUST fail."
The RFC doesn't specify an error, and the choice doesn't matter much as
this is clearly illegal client behavior, but bad_stateid seems
reasonable.
Simplest is just to guarantee that nfs4_preprocess_stateid_op, called
with non-NULL cstid, errors out if it can't return a stateid.
Reported-by: rtm@csail.mit.edu
Fixes: 624322f1ad ("NFSD add COPY_NOTIFY operation")
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Olga Kornievskaia <kolga@netapp.com>
Tested-by: Olga Kornievskaia <kolga@netapp.com>
I'm cutting back on my responsibilities. The NFS server and file
locking code are in good hands.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
These functions are related to file handle processing and have
nothing to do with XDR encoding or decoding. Also they are no longer
NFSv3-specific. As a clean-up, move their definitions to a more
appropriate location. WCC is also an NFSv3-specific term, so rename
them as general-purpose helpers.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
On the wire, I observed NFSv4 OPEN(CREATE) operations sometimes
returning a reasonable-looking value in the cinfo.before field and
zero in the cinfo.after field.
RFC 8881 Section 10.8.1 says:
> When a client is making changes to a given directory, it needs to
> determine whether there have been changes made to the directory by
> other clients. It does this by using the change attribute as
> reported before and after the directory operation in the associated
> change_info4 value returned for the operation.
and
> ... The post-operation change
> value needs to be saved as the basis for future change_info4
> comparisons.
A good quality client implementation therefore saves the zero
cinfo.after value. During a subsequent OPEN operation, it will
receive a different non-zero value in the cinfo.before field for
that directory, and it will incorrectly believe the directory has
changed, triggering an undesirable directory cache invalidation.
There are filesystem types where fs_supports_change_attribute()
returns false, tmpfs being one. On NFSv4 mounts, this means the
fh_getattr() call site in fill_pre_wcc() and fill_post_wcc() is
never invoked. Subsequently, nfsd4_change_attribute() is invoked
with an uninitialized @stat argument.
In fill_pre_wcc(), @stat contains stale stack garbage, which is
then placed on the wire. In fill_post_wcc(), ->fh_post_wc is all
zeroes, so zero is placed on the wire. Both of these values are
meaningless.
This fix can be applied immediately to stable kernels. Once there
are more regression tests in this area, this optimization can be
attempted again.
Fixes: 428a23d2bf ("nfsd: skip some unnecessary stats in the v4 case")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
According to commit bbf2f09883 ("nfsd: Reset the boot verifier on
all write I/O errors"), the Linux NFS server forces all clients to
resend pending unstable writes if any server-side write or commit
operation encounters an error (say, ENOSPC). This is a rare and
quite exceptional event that could require administrative recovery
action, so it should be made trace-able. Example trace event:
nfsd-938 [002] 7174.945558: nfsd_writeverf_reset: boot_time= 61cc920d xid=0xdcd62036 error=-28 new verifier=0x08aecc6142515904
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Clean up: These functions handle what the specs call a write
verifier, which in the Linux NFS server implementation is now
divorced from the server's boot instance
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
There are two boot-time fields in struct nfsd_net: one called
boot_time and one called nfssvc_boot. The latter is used only to
form write verifiers, but its documenting comment declares:
/* Time of server startup */
Since commit 27c438f53e ("nfsd: Support the server resetting the
boot verifier"), this field can be reset at any time; it's no
longer tied to server restart. So that comment is stale.
Also, according to pahole, struct timespec64 is 16 bytes long on
x86_64. The nfssvc_boot field is used only to form a write verifier,
which is 8 bytes long.
Let's clarify this situation by manufacturing an 8-byte verifier
in nfs_reset_boot_verifier() and storing only that in struct
nfsd_net.
We're grabbing 128 bits of time, so compress all of those into a
64-bit verifier instead of throwing out the high-order bits.
In the future, the siphash_key can be re-used for other hashed
objects per-nfsd_net.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
When vfs_iter_write() starts to fail because a file system is full,
a bunch of writes can fail at once with ENOSPC. These writes
repeatedly invoke nfsd_reset_boot_verifier() in quick succession.
Ensure that the time it grabs doesn't go backwards due to an ntp
adjustment going on at the same time.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Since a clone error commit can cause the boot verifier to change,
we should trace those errors.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
[ cel: Addressed a checkpatch.pl splat in fs/nfsd/vfs.h ]
The RWF_SYNC and !RWF_SYNC arms are now exactly alike except that
the RWF_SYNC arm resets the boot verifier twice in a row. Fix that
redundancy and de-duplicate the code.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The nfsd_file nf_rwsem is currently being used to separate file write
and commit instances to ensure that we catch errors and apply them to
the correct write/commit.
We can improve scalability at the expense of a little accuracy (some
extra false positives) by replacing the nf_rwsem with more careful
use of the errseq_t mechanism to track errors across the different
operations.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
[ cel: rebased on zero-verifier fix ]
RFC 8881 explains the purpose of the write verifier this way:
> The final portion of the result is the field writeverf. This field
> is the write verifier and is a cookie that the client can use to
> determine whether a server has changed instance state (e.g., server
> restart) between a call to WRITE and a subsequent call to either
> WRITE or COMMIT.
But then it says:
> This cookie MUST be unchanged during a single instance of the
> NFSv4.1 server and MUST be unique between instances of the NFSv4.1
> server. If the cookie changes, then the client MUST assume that
> any data written with an UNSTABLE4 value for committed and an old
> writeverf in the reply has been lost and will need to be
> recovered.
RFC 1813 has similar language for NFSv3. NFSv2 does not have a write
verifier since it doesn't implement the COMMIT procedure.
Since commit 19e0663ff9 ("nfsd: Ensure sampling of the write
verifier is atomic with the write"), the Linux NFS server has
returned a boot-time-based verifier for UNSTABLE WRITEs, but a zero
verifier for FILE_SYNC and DATA_SYNC WRITEs. FILE_SYNC and DATA_SYNC
WRITEs are not followed up with a COMMIT, so there's no need for
clients to compare verifiers for stable writes.
However, by returning a different verifier for stable and unstable
writes, the above commit puts the Linux NFS server a step farther
out of compliance with the first MUST above. At least one NFS client
(FreeBSD) noticed the difference, making this a potential
regression.
Reported-by: Rick Macklem <rmacklem@uoguelph.ca>
Link: https://lore.kernel.org/linux-nfs/YQXPR0101MB096857EEACF04A6DF1FC6D9BDD749@YQXPR0101MB0968.CANPRD01.PROD.OUTLOOK.COM/T/
Fixes: 19e0663ff9 ("nfsd: Ensure sampling of the write verifier is atomic with the write")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
If we get back -EOPENSTALE from an NFSv4 open, then we either got some
unhandled error or the inode we got back was not the same as the one
associated with the dentry.
We really have no recourse in that situation other than to retry the
open, and if it fails to just return nfserr_stale back to the client.
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The NFS client can occasionally return EREMOTEIO when signalling issues
with the server. ...map to NFSERR_IO.
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Now that we have open file cache, it is possible that another client
deletes the file and DP will not know about it. Then IO to MDS would
fail with BADSTATEID and knfsd would start state recovery, which
should fail as well and then nfs read/write will fail with EBADF.
And it triggers a WARN() in nfserrno().
-----------[ cut here ]------------
WARNING: CPU: 0 PID: 13529 at fs/nfsd/nfsproc.c:758 nfserrno+0x58/0x70 [nfsd]()
nfsd: non-standard errno: -9
modules linked in: nfsv3 nfs_layout_flexfiles rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_connt
pata_acpi floppy
CPU: 0 PID: 13529 Comm: nfsd Tainted: G W 4.1.5-00307-g6e6579b #7
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 09/30/2014
0000000000000000 00000000464e6c9c ffff88079085fba8 ffffffff81789936
0000000000000000 ffff88079085fc00 ffff88079085fbe8 ffffffff810a08ea
ffff88079085fbe8 ffff88080f45c900 ffff88080f627d50 ffff880790c46a48
all Trace:
[<ffffffff81789936>] dump_stack+0x45/0x57
[<ffffffff810a08ea>] warn_slowpath_common+0x8a/0xc0
[<ffffffff810a0975>] warn_slowpath_fmt+0x55/0x70
[<ffffffff81252908>] ? splice_direct_to_actor+0x148/0x230
[<ffffffffa02fb8c0>] ? fsid_source+0x60/0x60 [nfsd]
[<ffffffffa02f9918>] nfserrno+0x58/0x70 [nfsd]
[<ffffffffa02fba57>] nfsd_finish_read+0x97/0xb0 [nfsd]
[<ffffffffa02fc7a6>] nfsd_splice_read+0x76/0xa0 [nfsd]
[<ffffffffa02fcca1>] nfsd_read+0xc1/0xd0 [nfsd]
[<ffffffffa0233af2>] ? svc_tcp_adjust_wspace+0x12/0x30 [sunrpc]
[<ffffffffa03073da>] nfsd3_proc_read+0xba/0x150 [nfsd]
[<ffffffffa02f7a03>] nfsd_dispatch+0xc3/0x210 [nfsd]
[<ffffffffa0233af2>] ? svc_tcp_adjust_wspace+0x12/0x30 [sunrpc]
[<ffffffffa0232913>] svc_process_common+0x453/0x6f0 [sunrpc]
[<ffffffffa0232cc3>] svc_process+0x113/0x1b0 [sunrpc]
[<ffffffffa02f740f>] nfsd+0xff/0x170 [nfsd]
[<ffffffffa02f7310>] ? nfsd_destroy+0x80/0x80 [nfsd]
[<ffffffff810bf3a8>] kthread+0xd8/0xf0
[<ffffffff810bf2d0>] ? kthread_create_on_node+0x1b0/0x1b0
[<ffffffff817912a2>] ret_from_fork+0x42/0x70
[<ffffffff810bf2d0>] ? kthread_create_on_node+0x1b0/0x1b0
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The Linux NFS server currently responds to a zero-length NFSv3 WRITE
request with NFS3ERR_IO. It responds to a zero-length NFSv4 WRITE
with NFS4_OK and count of zero.
RFC 1813 says of the WRITE procedure's @count argument:
count
The number of bytes of data to be written. If count is
0, the WRITE will succeed and return a count of 0,
barring errors due to permissions checking.
RFC 8881 has similar language for NFSv4, though NFSv4 removed the
explicit @count argument because that value is already contained in
the opaque payload array.
The synthetic client pynfs's WRT4 and WRT15 tests do emit zero-
length WRITEs to exercise this spec requirement. Commit fdec6114ee
("nfsd4: zero-length WRITE should succeed") addressed the same
problem there with the same fix.
But interestingly the Linux NFS client does not appear to emit zero-
length WRITEs, instead squelching them. I'm not aware of a test that
can generate such WRITEs for NFSv3, so I wrote a naive C program to
generate a zero-length WRITE and test this fix.
Fixes: 8154ef2776 ("NFSD: Clean up legacy NFS WRITE argument XDR decoders")
Reported-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
nbl allocated in nfsd4_lock can be released by a several ways:
directly in nfsd4_lock(), via nfs4_laundromat(), via another nfs
command RELEASE_LOCKOWNER or via nfsd4_callback.
This structure should be refcounted to be used and released correctly
in all these cases.
Refcount is initialized to 1 during allocation and is incremented
when nbl is added into nbl_list/nbl_lru lists.
Usually nbl is linked into both lists together, so only one refcount
is used for both lists.
However nfsd4_lock() should keep in mind that nbl can be present
in one of lists only. This can happen if nbl was handled already
by nfs4_laundromat/nfsd4_callback/etc.
Refcount is decremented if vfs_lock_file() returns FILE_LOCK_DEFERRED,
because nbl can be handled already by nfs4_laundromat/nfsd4_callback/etc.
Refcount is not changed in find_blocked_lock() because of it reuses counter
released after removing nbl from lists.
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
NFSv4.1 supports an optional lock notification feature which notifies
the client when a lock comes available. (Normally NFSv4 clients just
poll for locks if necessary.) To make that work, we need to request a
blocking lock from the filesystem.
We turned that off for NFS in commit f657f8eef3 ("nfs: don't atempt
blocking locks on nfs reexports") [sic] because it actually blocks the
nfsd thread while waiting for the lock.
Thanks to Vasily Averin for pointing out that NFS isn't the only
filesystem with that problem.
Any filesystem that leaves ->lock NULL will use posix_lock_file(), which
does the right thing. Simplest is just to assume that any filesystem
that defines its own ->lock is not safe to request a blocking lock from.
So, this patch mostly reverts commit f657f8eef3 ("nfs: don't atempt
blocking locks on nfs reexports") [sic] and commit b840be2f00 ("lockd:
don't attempt blocking locks on nfs reexports"), and instead uses a
check of ->lock (Vasily's suggestion) to decide whether to support
blocking lock notifications on a given filesystem. Also add a little
documentation.
Perhaps someday we could add back an export flag later to allow
filesystems with "good" ->lock methods to support blocking lock
notifications.
Reported-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
[ cel: Description rewritten to address checkpatch nits ]
[ cel: Fixed warning when SUNRPC debugging is disabled ]
[ cel: Fixed NULL check ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Vasily Averin <vvs@virtuozzo.com>
Clean up. Trond points out that xdr_stream_decode_uint32_array()
does the same thing as nfsd4_decode_bitmap4().
Suggested-by: Trond Myklebust <trondmy@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The use of the bitmaps is confusing. Add a cross-reference to make it
easier to find the existing comment. Add an updated reference with URL
to make it quicker to look up. And a bit more editorializing about the
value of this.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Clean up: The garbage_args and cant_encode tracepoints report the
same information as each other, so combine them into a single
tracepoint class to reduce code duplication and slightly reduce the
size of trace.o.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
I'm about to add more information to the server-side SUNRPC
tracepoints, so I'm going to offset the increased trace log
consumption by getting rid of some tracepoints that fire frequently
but don't offer much value.
trace_svc_xprt_received() was useful for debugging, perhaps, but
is not generally informative.
trace_svc_handle_xprt() reports largely the same information as
trace_svc_xdr_recvfrom().
As a clean-up, rename trace_svc_xprt_do_enqueue() to match
svc_xprt_dequeue().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
We currently have a 'laundrette' for closing cached files - a different
work-item for each network-namespace.
These 'laundrettes' (aka struct nfsd_fcache_disposal) are currently on a
list, and are freed using rcu.
The list is not necessary as we have a per-namespace structure (struct
nfsd_net) which can hold a link to the nfsd_fcache_disposal.
The use of kfree_rcu is also unnecessary as the cache is cleaned of all
files associated with a given namespace, and no new files can be added,
before the nfsd_fcache_disposal is freed.
So add a '->fcache_disposal' link to nfsd_net, and discard the list
management and rcu usage.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Commit 7142b98d9f ("nfsd: Clean up drc cache in preparation for
global spinlock elimination"), billed as a clean-up, added
be32_to_cpu() to the DRC hash function without explanation. That
commit removed two comments that state that byte-swapping in the
hash function is unnecessary without explaining whether there was
a need for that change.
On some Intel CPUs, the swab32 instruction is known to cause a CPU
pipeline stall. be32_to_cpu() does not add extra randomness, since
the hash multiplication is done /before/ shifting to the high-order
bits of the result.
As a micro-optimization, remove the unnecessary transform from the
DRC hash function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Now that thread management is consistent there is no need for
nfs-callback to use svc_create_pooled() as introduced in Commit
df807fffaa ("NFSv4.x/callback: Create the callback service through
svc_create_pooled"). So switch back to svc_create().
If service pools were configured, but the number of threads were left at
'1', nfs callback may not work reliably when svc_create_pooled() is used.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
svc_set_num_threads() does everything that lockd_start_svc() does, except
set sv_maxconn. It also (when passed 0) finds the threads and
stops them with kthread_stop().
So move the setting for sv_maxconn, and use svc_set_num_thread()
We now don't need nlmsvc_task.
Now that we use svc_set_num_threads() it makes sense to set svo_module.
This request that the thread exists with module_put_and_exit().
Also fix the documentation for svo_module to make this explicit.
svc_prepare_thread is now only used where it is defined, so it can be
made static.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Currently 'pooled' services hold a reference on the pool_map, and
'unpooled' services do not.
svc_destroy() uses the presence of ->svo_function (via
svc_serv_is_pooled()) to determine if the reference should be dropped.
There is no direct correlation between being pooled and the use of
svo_function, though in practice, lockd is the only non-pooled service,
and the only one not to use svo_function.
This is untidy and would cause problems if we changed lockd to use
svc_set_num_threads(), which requires the use of ->svo_function.
So change the test for "is the service pooled" to "is sv_nrpools > 1".
This means that when svc_pool_map_get() returns 1, it must NOT take a
reference to the pool.
We discard svc_serv_is_pooled(), and test sv_nrpools directly.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
These definitions are not used outside of svc.c, and there is no
evidence that they ever have been. So move them into svc.c
and make the declarations 'static'.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
lockd_create_svc() already does an svc_get() if the service already
exists, so it is more like a "get" than a "create".
So:
- Move the increment of nlmsvc_users into the function as well
- rename to lockd_get().
It is now the inverse of lockd_put().
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
There is some cleanup that is duplicated in lockd_down() and the failure
path of lockd_up().
Factor these out into a new lockd_put() and call it from both places.
lockd_put() does *not* take the mutex - that must be held by the caller.
It decrements nlmsvc_users and if that reaches zero, it cleans up.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The normal place to call svc_exit_thread() is from the thread itself
just before it exists.
Do this for lockd.
This means that nlmsvc_rqst is not used out side of lockd_start_svc(),
so it can be made local to that function, and renamed to 'rqst'.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
lockd_start_svc() only needs to be called once, just after the svc is
created. If the start fails, the svc is discarded too.
It thus makes sense to call lockd_start_svc() from lockd_create_svc().
This allows us to remove the test against nlmsvc_rqst at the start of
lockd_start_svc() - it must always be NULL.
lockd_up() only held an extra reference on the svc until a thread was
created - then it dropped it. The thread - and thus the extra reference
- will remain until kthread_stop() is called.
Now that the thread is created in lockd_create_svc(), the extra
reference can be dropped there. So the 'serv' variable is no longer
needed in lockd_up().
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Now that the network status notifiers use nlmsvc_serv rather then
nlmsvc_rqst the management can be simplified.
Notifier unregistration synchronises with any pending notifications so
providing we unregister before nlm_serv is freed no further interlock
is required.
So we move the unregister call to just before the thread is killed
(which destroys the service) and just before the service is destroyed in
the failure-path of lockd_up().
Then nlm_ntf_refcnt and nlm_ntf_wq can be removed.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
lockd has two globals - nlmsvc_task and nlmsvc_rqst - but mostly it
wants the 'struct svc_serv', and when it doesn't want it exactly it can
get to what it wants from the serv.
This patch is a first step to removing nlmsvc_task and nlmsvc_rqst. It
introduces nlmsvc_serv to store the 'struct svc_serv*'. This is set as
soon as the serv is created, and cleared only when it is destroyed.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
nfsd currently maintains an open-coded read/write semaphore (refcount
and wait queue) for each network namespace to ensure the nfs service
isn't shut down while the notifier is running.
This is excessive. As there is unlikely to be contention between
notifiers and they run without sleeping, a single spinlock is sufficient
to avoid problems.
Signed-off-by: NeilBrown <neilb@suse.de>
[ cel: ensure nfsd_notifier_lock is static ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The ->svo_setup callback serves no purpose. It is always called from
within the same module that chooses which callback is needed. So
discard it and call the relevant function directly.
Now that svc_set_num_threads() is no longer used remove it and rename
svc_set_num_threads_sync() to remove the "_sync" suffix.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
nfsd cannot currently use svc_set_num_threads_sync. It instead
uses svc_set_num_threads which does *not* wait for threads to all
exit, and has a separate mechanism (nfsd_shutdown_complete) to wait
for completion.
The reason that nfsd is unlike other services is that nfsd threads can
exit separately from svc_set_num_threads being called - they die on
receipt of SIGKILL. Also, when the last thread exits, the service must
be shut down (sockets closed).
For this, the nfsd_mutex needs to be taken, and as that mutex needs to
be held while svc_set_num_threads is called, the one cannot wait for
the other.
This patch changes the nfsd thread so that it can drop the ref on the
service without blocking on nfsd_mutex, so that svc_set_num_threads_sync
can be used:
- if it can drop a non-last reference, it does that. This does not
trigger shutdown and does not require a mutex. This will likely
happen for all but the last thread signalled, and for all threads
being shut down by nfsd_shutdown_threads()
- if it can get the mutex without blocking (trylock), it does that
and then drops the reference. This will likely happen for the
last thread killed by SIGKILL
- Otherwise there might be an unrelated task holding the mutex,
possibly in another network namespace, or nfsd_shutdown_threads()
might be just about to get a reference on the service, after which
we can drop ours safely.
We cannot conveniently get wakeup notifications on these events,
and we are unlikely to need to, so we sleep briefly and check again.
With this we can discard nfsd_shutdown_complete and
nfsd_complete_shutdown(), and switch to svc_set_num_threads_sync.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
There is nothing happening in the start of nfsd() that requires
protection by the mutex, so don't take it until shutting down the thread
- which does still require protection - but only for nfsd_put().
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Using sv_lock means we don't need to hold the service mutex over these
updates.
In particular, svc_exit_thread() no longer requires synchronisation, so
threads can exit asynchronously.
Note that we could use an atomic_t, but as there are many more read
sites than writes, that would add unnecessary noise to the code.
Some reads are already racy, and there is no need for them to not be.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This allows us to move the updates for th_cnt out of the mutex.
This is a step towards reducing mutex coverage in nfsd().
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The use of sv_nrthreads as a general refcount results in clumsy code, as
is seen by various comments needed to explain the situation.
This patch introduces a 'struct kref' and uses that for reference
counting, leaving sv_nrthreads to be a pure count of threads. The kref
is managed particularly in svc_get() and svc_put(), and also nfsd_put();
svc_destroy() now takes a pointer to the embedded kref, rather than to
the serv.
nfsd allows the svc_serv to exist with ->sv_nrhtreads being zero. This
happens when a transport is created before the first thread is started.
To support this, a 'keep_active' flag is introduced which holds a ref on
the svc_serv. This is set when any listening socket is successfully
added (unless there are running threads), and cleared when the number of
threads is set. So when the last thread exits, the nfs_serv will be
destroyed.
The use of 'keep_active' replaces previous code which checked if there
were any permanent sockets.
We no longer clear ->rq_server when nfsd() exits. This was done
to prevent svc_exit_thread() from calling svc_destroy().
Instead we take an extra reference to the svc_serv to prevent
svc_destroy() from being called.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
