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The following request sequence to the same file causes the NFS client and
server getting into an infinite loop with COMMIT and NFS4ERR_DELAY:
OPEN
REMOVE
WRITE
COMMIT
Problem reported by recall11, recall12, recall14, recall20, recall22,
recall40, recall42, recall48, recall50 of nfstest suite.
This patch restores the handling of race condition in nfsd_file_do_acquire
with unlink to that prior of the regression.
Fixes: ac3a2585f018 ("nfsd: rework refcounting in filecache")
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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When queueing a dispose list to the appropriate "freeme" lists, it
pointlessly queues the objects one at a time to an intermediate list.
Remove a few helpers and just open code a list_move to make it more
clear and efficient. Better document the resulting functions with
kerneldoc comments.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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While we were converting the nfs4_file hashtable to use the kernel's
resizable hashtable data structure, Neil Brown observed that the
list variant (rhltable) would be better for managing nfsd_file items
as well. The nfsd_file hash table will contain multiple entries for
the same inode -- these should be kept together on a list. And, it
could be possible for exotic or malicious client behavior to cause
the hash table to resize itself on every insertion.
A nice simplification is that rhltable_lookup() can return a list
that contains only nfsd_file items that match a given inode, which
enables us to eliminate specialized hash table helper functions and
use the default functions provided by the rhashtable implementation).
Since we are now storing nfsd_file items for the same inode on a
single list, that effectively reduces the number of hash entries
that have to be tracked in the hash table. The mininum bucket count
is therefore lowered.
Light testing with fstests generic/531 show no regressions.
Suggested-by: Neil Brown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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On most filesystems, there is no reason to delay reaping an nfsd_file
just because its underlying inode is still under writeback. nfsd just
relies on client activity or the local flusher threads to do writeback.
The main exception is NFS, which flushes all of its dirty data on last
close. Add a new EXPORT_OP_FLUSH_ON_CLOSE flag to allow filesystems to
signal that they do this, and only skip closing files under writeback on
such filesystems.
Also, remove a redundant NULL file pointer check in
nfsd_file_check_writeback, and clean up nfs's export op flag
definitions.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The last thing that filp_close does is an fput, so don't bother taking
and putting the extra reference.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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David Howells mentioned that he found this bit of code confusing, so
sprinkle in some comments to clarify.
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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An error from break_lease is non-fatal, so we needn't destroy the
nfsd_file in that case. Just put the reference like we normally would
and return the error.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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test_bit returns bool, so we can just compare the result of that to the
key->gc value without the "!!".
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Since v4 files are expected to be long-lived, there's little value in
closing them out of the cache when there is conflicting access.
Change the comparator to also match the gc value in the key. Change both
of the current users of that key to set the gc value in the key to
"true".
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Most of the time, NFSv4 clients issue a COMMIT before the final CLOSE of
an open stateid, so with NFSv4, the fsync in the nfsd_file_free path is
usually a no-op and doesn't block.
We have a customer running knfsd over very slow storage (XFS over Ceph
RBD). They were using the "async" export option because performance was
more important than data integrity for this application. That export
option turns NFSv4 COMMIT calls into no-ops. Due to the fsync in this
codepath however, their final CLOSE calls would still stall (since a
CLOSE effectively became a COMMIT).
I think this fsync is not strictly necessary. We only use that result to
reset the write verifier. Instead of fsync'ing all of the data when we
free an nfsd_file, we can just check for writeback errors when one is
acquired and when it is freed.
If the client never comes back, then it'll never see the error anyway
and there is no point in resetting it. If an error occurs after the
nfsd_file is removed from the cache but before the inode is evicted,
then it will reset the write verifier on the next nfsd_file_acquire,
(since there will be an unseen error).
The only exception here is if something else opens and fsyncs the file
during that window. Given that local applications work with this
limitation today, I don't see that as an issue.
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2166658
Fixes: ac3a2585f018 ("nfsd: rework refcounting in filecache")
Reported-and-tested-by: Pierguido Lambri <plambri@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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...and remove some now-useless NULL pointer checks in its callers.
Suggested-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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nfsd_file_cache_purge is called when the server is shutting down, in
which case, tearing things down is generally fine, but it also gets
called when the exports cache is flushed.
Instead of walking the cache and freeing everything unconditionally,
handle it the same as when we have a notification of conflicting access.
Fixes: ac3a2585f018 ("nfsd: rework refcounting in filecache")
Reported-by: Ruben Vestergaard <rubenv@drcmr.dk>
Reported-by: Torkil Svensgaard <torkil@drcmr.dk>
Reported-by: Shachar Kagan <skagan@nvidia.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Shachar Kagan <skagan@nvidia.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Commit fb70bf124b05 ("NFSD: Instantiate a struct file when creating a
regular NFSv4 file") added the ability to cache an open fd over a
compound. There are a couple of problems with the way this currently
works:
It's racy, as a newly-created nfsd_file can end up with its PENDING bit
cleared while the nf is hashed, and the nf_file pointer is still zeroed
out. Other tasks can find it in this state and they expect to see a
valid nf_file, and can oops if nf_file is NULL.
Also, there is no guarantee that we'll end up creating a new nfsd_file
if one is already in the hash. If an extant entry is in the hash with a
valid nf_file, nfs4_get_vfs_file will clobber its nf_file pointer with
the value of op_file and the old nf_file will leak.
Fix both issues by making a new nfsd_file_acquirei_opened variant that
takes an optional file pointer. If one is present when this is called,
we'll take a new reference to it instead of trying to open the file. If
the nfsd_file already has a valid nf_file, we'll just ignore the
optional file and pass the nfsd_file back as-is.
Also rework the tracepoints a bit to allow for an "opened" variant and
don't try to avoid counting acquisitions in the case where we already
have a cached open file.
Fixes: fb70bf124b05 ("NFSD: Instantiate a struct file when creating a regular NFSv4 file")
Cc: Trond Myklebust <trondmy@hammerspace.com>
Reported-by: Stanislav Saner <ssaner@redhat.com>
Reported-and-Tested-by: Ruben Vestergaard <rubenv@drcmr.dk>
Reported-and-Tested-by: Torkil Svensgaard <torkil@drcmr.dk>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The filecache refcounting is a bit non-standard for something searchable
by RCU, in that we maintain a sentinel reference while it's hashed. This
in turn requires that we have to do things differently in the "put"
depending on whether its hashed, which we believe to have led to races.
There are other problems in here too. nfsd_file_close_inode_sync can end
up freeing an nfsd_file while there are still outstanding references to
it, and there are a number of subtle ToC/ToU races.
Rework the code so that the refcount is what drives the lifecycle. When
the refcount goes to zero, then unhash and rcu free the object. A task
searching for a nfsd_file is allowed to bump its refcount, but only if
it's not already 0. Ensure that we don't make any other changes to it
until a reference is held.
With this change, the LRU carries a reference. Take special care to deal
with it when removing an entry from the list, and ensure that we only
repurpose the nf_lru list_head when the refcount is 0 to ensure
exclusive access to it.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add a tracepoint to capture the number of filecache-triggered fsync
calls and which files needed it. Also, record when an fsync triggers
a write verifier reset.
Examples:
<...>-97 [007] 262.505611: nfsd_file_free: inode=0xffff888171e08140 ref=0 flags=GC may=WRITE nf_file=0xffff8881373d2400
<...>-97 [007] 262.505612: nfsd_file_fsync: inode=0xffff888171e08140 ref=0 flags=GC may=WRITE nf_file=0xffff8881373d2400 ret=0
<...>-97 [007] 262.505623: nfsd_file_free: inode=0xffff888171e08dc0 ref=0 flags=GC may=WRITE nf_file=0xffff8881373d1e00
<...>-97 [007] 262.505624: nfsd_file_fsync: inode=0xffff888171e08dc0 ref=0 flags=GC may=WRITE nf_file=0xffff8881373d1e00 ret=0
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
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We don't really care whether there are hashed entries when it comes to
scheduling the laundrette. They might all be non-gc entries, after all.
We only want to schedule it if there are entries on the LRU.
Switch to using list_lru_count, and move the check into
nfsd_file_gc_worker. The other callsite in nfsd_file_put doesn't need to
count entries, since it only schedules the laundrette after adding an
entry to the LRU.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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In a coming patch, we're going to rework how the filecache refcounting
works. Move some code around in the function to reduce the churn in the
later patches, and rename some of the functions with (hopefully) clearer
names: nfsd_file_flush becomes nfsd_file_fsync, and
nfsd_file_unhash_and_dispose is renamed to nfsd_file_unhash_and_queue.
Also, the nfsd_file_put_final tracepoint is renamed to nfsd_file_free,
to better match the name of the function from which it's called.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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We're counting mapping->nrpages, but not all of those are necessarily
dirty. We don't really have a simple way to count just the dirty pages,
so just remove this stat since it's not accurate.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add a missing SPDX header.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
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Record what we've learned recently about the NFSD filecache in a
documenting comment so our future selves don't forget what all this
is for.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
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NFSv4 operations manage the lifetime of nfsd_file items they use by
means of NFSv4 OPEN and CLOSE. Hence there's no need for them to be
garbage collected.
Introduce a mechanism to enable garbage collection for nfsd_file
items used only by NFSv2/3 callers.
Note that the change in nfsd_file_put() ensures that both CLOSE and
DELEGRETURN will actually close out and free an nfsd_file on last
reference of a non-garbage-collected file.
Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=394
Suggested-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
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This reverts commit 5e138c4a750dc140d881dab4a8804b094bbc08d2.
That commit attempted to make files available to other users as soon
as all NFSv4 clients were done with them, rather than waiting until
the filecache LRU had garbage collected them.
It gets the reference counting wrong, for one thing.
But it also misses that DELEGRETURN should release a file in the
same fashion. In fact, any nfsd_file_put() on an file held open
by an NFSv4 client needs potentially to release the file
immediately...
Clear the way for implementing that idea.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
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When we fail to insert into the hashtable with a non-retryable error,
we'll free the object and then goto out_status. If the tracepoint is
enabled, it'll end up accessing the freed object when it tries to
grab the fields out of it.
Set nf to NULL after freeing it to avoid the issue.
Fixes: 243a5263014a ("nfsd: rework hashtable handling in nfsd_do_file_acquire")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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If the namespace doesn't match the one in "net", then we'll continue,
but that doesn't cause another rhashtable_walk_next call, so it will
loop infinitely.
Fixes: ce502f81ba88 ("NFSD: Convert the filecache to use rhashtable")
Reported-by: Petr Vorel <pvorel@suse.cz>
Link: https://lore.kernel.org/ltp/Y1%2FP8gDAcWC%2F+VR3@pevik/
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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nfsd_file is RCU-freed, so we need to hold the rcu_read_lock long enough
to get a reference after finding it in the hash. Take the
rcu_read_lock() and call rhashtable_lookup directly.
Switch to using rhashtable_lookup_insert_key as well, and use the usual
retry mechanism if we hit an -EEXIST. Rename the "retry" bool to
open_retry, and eliminiate the insert_err goto target.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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nfsd_file_unhash_and_dispose() is called for two reasons:
We're either shutting down and purging the filecache, or we've gotten a
notification about a file delete, so we want to go ahead and unhash it
so that it'll get cleaned up when we close.
We're either walking the hashtable or doing a lookup in it and we
don't take a reference in either case. What we want to do in both cases
is to try and unhash the object and put it on the dispose list if that
was successful. If it's no longer hashed, then we don't want to touch
it, with the assumption being that something else is already cleaning
up the sentinel reference.
Instead of trying to selectively decrement the refcount in this
function, just unhash it, and if that was successful, move it to the
dispose list. Then, the disposal routine will just clean that up as
usual.
Also, just make this a void function, drop the WARN_ON_ONCE, and the
comments about deadlocking since the nature of the purported deadlock
is no longer clear.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Use DEFINE_SHOW_ATTRIBUTE helper macro to simplify the code.
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Pull nfsd updates from Chuck Lever:
"Work on 'courteous server', which was introduced in 5.19, continues
apace. This release introduces a more flexible limit on the number of
NFSv4 clients that NFSD allows, now that NFSv4 clients can remain in
courtesy state long after the lease expiration timeout. The client
limit is adjusted based on the physical memory size of the server.
The NFSD filecache is a cache of files held open by NFSv4 clients or
recently touched by NFSv2 or NFSv3 clients. This cache had some
significant scalability constraints that have been relieved in this
release. Thanks to all who contributed to this work.
A data corruption bug found during the most recent NFS bake-a-thon
that involves NFSv3 and NFSv4 clients writing the same file has been
addressed in this release.
This release includes several improvements in CPU scalability for
NFSv4 operations. In addition, Neil Brown provided patches that
simplify locking during file lookup, creation, rename, and removal
that enables subsequent work on making these operations more scalable.
We expect to see that work materialize in the next release.
There are also numerous single-patch fixes, clean-ups, and the usual
improvements in observability"
* tag 'nfsd-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (78 commits)
lockd: detect and reject lock arguments that overflow
NFSD: discard fh_locked flag and fh_lock/fh_unlock
NFSD: use (un)lock_inode instead of fh_(un)lock for file operations
NFSD: use explicit lock/unlock for directory ops
NFSD: reduce locking in nfsd_lookup()
NFSD: only call fh_unlock() once in nfsd_link()
NFSD: always drop directory lock in nfsd_unlink()
NFSD: change nfsd_create()/nfsd_symlink() to unlock directory before returning.
NFSD: add posix ACLs to struct nfsd_attrs
NFSD: add security label to struct nfsd_attrs
NFSD: set attributes when creating symlinks
NFSD: introduce struct nfsd_attrs
NFSD: verify the opened dentry after setting a delegation
NFSD: drop fh argument from alloc_init_deleg
NFSD: Move copy offload callback arguments into a separate structure
NFSD: Add nfsd4_send_cb_offload()
NFSD: Remove kmalloc from nfsd4_do_async_copy()
NFSD: Refactor nfsd4_do_copy()
NFSD: Refactor nfsd4_cleanup_inter_ssc() (2/2)
NFSD: Refactor nfsd4_cleanup_inter_ssc() (1/2)
...
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The documenting comment for struct nf_file states:
/*
* A representation of a file that has been opened by knfsd. These are hashed
* in the hashtable by inode pointer value. Note that this object doesn't
* hold a reference to the inode by itself, so the nf_inode pointer should
* never be dereferenced, only used for comparison.
*/
Replace the two existing dereferences to make the comment always
true.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The last close of a file should enable other accessors to open and
use that file immediately. Leaving the file open in the filecache
prevents other users from accessing that file until the filecache
garbage-collects the file -- sometimes that takes several seconds.
Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Link: https://bugzilla.linux-nfs.org/show_bug.cgi?387
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Avoid recording the allocation of an nfsd_file item that is
immediately released because a matching item was already
inserted in the hash.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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These tracepoints collect different information: the create case does
not open a file, so there's no nf_file available.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Enable the filecache hash table to start small, then grow with the
workload. Smaller server deployments benefit because there should
be lower memory utilization. Larger server deployments should see
improved scaling with the number of open files.
Suggested-by: Jeff Layton <jlayton@kernel.org>
Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add code to initialize and tear down an rhashtable. The rhashtable
is not used yet.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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In a moment, the nfsd_file_hashtbl global will be replaced with an
rhashtable. Replace the one or two spots that need to check if the
hash table is available. We can easily reuse the SHUTDOWN flag for
this purpose.
Document that this mechanism relies on callers to hold the
nfsd_mutex to prevent init, shutdown, and purging to run
concurrently.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The value in this field can always be computed from nf_inode, thus
it is no longer used.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Remove an unnecessary use of nf_hashval.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The code that computes the hashval is the same in both callers.
To prevent them from going stale, reframe the documenting comments
to remove descriptions of the underlying hash table structure, which
is about to be replaced.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Remove an unnecessary usage of nf_hashval.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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IIUC, holding the hash bucket lock is needed only in
nfsd_file_unhash, and there is already a lockdep assertion there.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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I'm about to replace nfsd_file_hashtbl with an rhashtable. The
individual hash values will no longer be visible or relevant, so
remove them from the tracepoints.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The checks in nfsd_file_acquire() and nfsd_file_put() that directly
invoke filecache garbage collection are intended to keep cache
occupancy between a low- and high-watermark. The reason to limit the
capacity of the filecache is to keep filecache lookups reasonably
fast.
However, invoking garbage collection at those points has some
undesirable negative impacts. Files that are held open by NFSv4
clients often push the occupancy of the filecache over these
watermarks. At that point:
- Every call to nfsd_file_acquire() and nfsd_file_put() results in
an LRU walk. This has the same effect on lookup latency as long
chains in the hash table.
- Garbage collection will then run on every nfsd thread, causing a
lot of unnecessary lock contention.
- Limiting cache capacity pushes out files used only by NFSv3
clients, which are the type of files the filecache is supposed to
help.
To address those negative impacts, remove the direct calls to the
garbage collector. Subsequent patches will address maintaining
lookup efficiency as cache capacity increases.
Suggested-by: Wang Yugui <wangyugui@e16-tech.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Without LRU item rotation, the shrinker visits only a few items on
the end of the LRU list, and those would always be long-term OPEN
files for NFSv4 workloads. That makes the filecache shrinker
completely ineffective.
Adopt the same strategy as the inode LRU by using LRU_ROTATE.
Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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There have been reports of problems when running fstests generic/531
against Linux NFS servers with NFSv4. The NFS server that hosts the
test's SCRATCH_DEV suffers from CPU soft lock-ups during the test.
Analysis shows that:
fs/nfsd/filecache.c
482 ret = list_lru_walk(&nfsd_file_lru,
483 nfsd_file_lru_cb,
484 &head, LONG_MAX);
causes nfsd_file_gc() to walk the entire length of the filecache LRU
list every time it is called (which is quite frequently). The walk
holds a spinlock the entire time that prevents other nfsd threads
from accessing the filecache.
What's more, for NFSv4 workloads, none of the items that are visited
during this walk may be evicted, since they are all files that are
held OPEN by NFS clients.
Address this by ensuring that open files are not kept on the LRU
list.
Reported-by: Frank van der Linden <fllinden@amazon.com>
Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=386
Suggested-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observe the operation of garbage collection and the lifetime of
filecache items.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add a guardrail to prevent freeing memory that is still on a list.
This includes either a dispose list or the LRU list.
This is the sign of a bug, but this class of bugs can be detected
so that they don't endanger system stability, especially while
debugging.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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If nfsd_file_cache_init() is called after a shutdown, be sure the
stat counters are reset.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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