[ Upstream commit 91d2e9b56cf5c80f9efc530d494968369a8a0e0d ]
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 27c438f53e79 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 1463b38e7cf34d4cc60f41daff459ad807b2e408 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit d057cfec4940ce6eeffa22b4a71dec203b06cd55 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 3409e4f1e8f239f0ed81be0b068ecf4e73e2e826 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit ec52361df99b490f6af412b046df9799b92c1050 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit f4e44b393389c77958f7c58bf4415032b4cda15b ]
Currently the source's export is mounted and unmounted on every
inter-server copy operation. This patch is an enhancement to delay
the unmount of the source export for a certain period of time to
eliminate the mount and unmount overhead on subsequent copy operations.
After a copy operation completes, a work entry is added to the
delayed unmount list with an expiration time. This list is serviced
by the laundromat thread to unmount the export of the expired entries.
Each time the export is being used again, its expiration time is
extended and the entry is re-inserted to the tail of the list.
The unmount task and the mount operation of the copy request are
synced to make sure the export is not unmounted while it's being
used.
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e567b98ce9a4b35b63c364d24828a9e5cd7a8179 ]
nfsd stats counters can be updated by concurrent nfsd threads without any
protection.
Convert some nfsd_stats and nfsd_net struct members to use percpu counters.
The longest_chain* members of struct nfsd_net remain unprotected.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
