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Observability here is now covered by static tracepoints.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observability here is now covered by static tracepoints.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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There isn't a common helper for getattrs, so add these into the
protocol-specific helpers.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observe the start of NFS READDIR operations.
The NFS READDIR's count argument can be interesting when tuning a
client's readdir behavior.
However, the count argument is not passed to nfsd_readdir(). To
properly capture the count argument, this tracepoint must appear in
each proc function before the nfsd_readdir() call.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observe the start of RENAME operations for all NFS versions.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observe the start of UNLINK, REMOVE, and RMDIR operations for all
NFS versions.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observe the start of NFS LINK operations.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observe the start of SYMLINK operations for all NFS versions.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Observe the start of file and directory creation for all NFS
versions.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Replace the dprintk in nfsd_lookup_dentry() with a trace point.
nfsd_lookup_dentry() is called frequently enough that enabling this
dprintk call site would result in log floods and performance issues.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Turn Sargun's internal kprobe based implementation of this into a normal
static tracepoint. Also, remove the dprintk's that got added recently
with the fix for zero-length ACLs.
Cc: Sargun Dillon <sargun@sargun.me>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Introduce tracing helpers that can be used before the procedure
status code is known. These macros are similar to the
SVC_RQST_ENDPOINT helpers, but they can be modified to include
NFS-specific fields if that is needed later.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Record and emit presentation addresses using tracing helpers
designed for the task.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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RFC 7862 states that if an NFS server implements a CLONE operation,
it MUST also implement FATTR4_CLONE_BLKSIZE. NFSD implements CLONE,
but does not implement FATTR4_CLONE_BLKSIZE.
Note that in Section 12.2, RFC 7862 claims that
FATTR4_CLONE_BLKSIZE is RECOMMENDED, not REQUIRED. Likely this is
because a minor version is not permitted to add a REQUIRED
attribute. Confusing.
We assume this attribute reports a block size as a count of bytes,
as RFC 7862 does not specify a unit.
Reported-by: Roland Mainz <roland.mainz@nrubsig.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
Cc: stable@vger.kernel.org # v6.7+
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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This user of SHA-256 does not support any other algorithm, so the
crypto_shash abstraction provides no value. Just use the SHA-256
library API instead, which is much simpler and easier to use.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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In nfs4_state_start_net(), laundromat_work may access nfsd_ssc through
nfs4_laundromat -> nfsd4_ssc_expire_umount. If nfsd_ssc isn't initialized,
this can cause NULL pointer dereference.
Normally the delayed start of laundromat_work allows sufficient time for
nfsd_ssc initialization to complete. However, when the kernel waits too
long for userspace responses (e.g. in nfs4_state_start_net ->
nfsd4_end_grace -> nfsd4_record_grace_done -> nfsd4_cld_grace_done ->
cld_pipe_upcall -> __cld_pipe_upcall -> wait_for_completion path), the
delayed work may start before nfsd_ssc initialization finishes.
Fix this by moving nfsd_ssc initialization before starting laundromat_work.
Fixes: f4e44b393389 ("NFSD: delay unmount source's export after inter-server copy completed.")
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Very useful for gauging how long the vfs_fsync_range() takes.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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If the request being processed is not a v4 compound request, then
examining the cstate can have undefined results.
This patch adds a check that the rpc procedure being executed
(rq_procinfo) is the NFSPROC4_COMPOUND procedure.
Reported-by: Olga Kornievskaia <okorniev@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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When an export policy with xprtsec policy is set with "tls"
and/or "mtls", but an NFS client is doing a v3 xprtsec=tls
mount, then NLM locking calls fail with an error because
there is currently no support for NLM with TLS.
Until such support is added, allow NLM calls under TLS-secured
policy.
Fixes: 4cc9b9f2bf4d ("nfsd: refine and rename NFSD_MAY_LOCK")
Cc: stable@vger.kernel.org
Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
Reviewed-by: NeilBrown <neil@brown.name>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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It can be removed since svc_fill_write_vector already has the
same WARN_ON_ONCE.
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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NFSD currently has two separate code paths for handling read
requests. One uses page splicing; the other is a traditional read
based on an iov iterator.
Because most Linux file systems support splice read, the latter
does not get nearly the same test experience as splice reads.
To force the use of vectored reads for testing and benchmarking,
introduce the ability to disable splice reads for all NFS READ
operations.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Create a small sandbox under /sys/kernel/debug for experimental NFS
server feature settings. There is no API/ABI compatibility guarantee
for these settings.
The only documentation for such settings, if any documentation exists,
is in the kernel source code.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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As of now nfsd calls create_proc_exports_entry() at start of init_nfsd
and cleanup by remove_proc_entry() at last of exit_nfsd.
Which causes kernel OOPs if there is race between below 2 operations:
(i) exportfs -r
(ii) mount -t nfsd none /proc/fs/nfsd
for 5.4 kernel ARM64:
CPU 1:
el1_irq+0xbc/0x180
arch_counter_get_cntvct+0x14/0x18
running_clock+0xc/0x18
preempt_count_add+0x88/0x110
prep_new_page+0xb0/0x220
get_page_from_freelist+0x2d8/0x1778
__alloc_pages_nodemask+0x15c/0xef0
__vmalloc_node_range+0x28c/0x478
__vmalloc_node_flags_caller+0x8c/0xb0
kvmalloc_node+0x88/0xe0
nfsd_init_net+0x6c/0x108 [nfsd]
ops_init+0x44/0x170
register_pernet_operations+0x114/0x270
register_pernet_subsys+0x34/0x50
init_nfsd+0xa8/0x718 [nfsd]
do_one_initcall+0x54/0x2e0
CPU 2 :
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
PC is at : exports_net_open+0x50/0x68 [nfsd]
Call trace:
exports_net_open+0x50/0x68 [nfsd]
exports_proc_open+0x2c/0x38 [nfsd]
proc_reg_open+0xb8/0x198
do_dentry_open+0x1c4/0x418
vfs_open+0x38/0x48
path_openat+0x28c/0xf18
do_filp_open+0x70/0xe8
do_sys_open+0x154/0x248
Sometimes it crashes at exports_net_open() and sometimes cache_seq_next_rcu().
and same is happening on latest 6.14 kernel as well:
[ 0.000000] Linux version 6.14.0-rc5-next-20250304-dirty
...
[ 285.455918] Unable to handle kernel paging request at virtual address 00001f4800001f48
...
[ 285.464902] pc : cache_seq_next_rcu+0x78/0xa4
...
[ 285.469695] Call trace:
[ 285.470083] cache_seq_next_rcu+0x78/0xa4 (P)
[ 285.470488] seq_read+0xe0/0x11c
[ 285.470675] proc_reg_read+0x9c/0xf0
[ 285.470874] vfs_read+0xc4/0x2fc
[ 285.471057] ksys_read+0x6c/0xf4
[ 285.471231] __arm64_sys_read+0x1c/0x28
[ 285.471428] invoke_syscall+0x44/0x100
[ 285.471633] el0_svc_common.constprop.0+0x40/0xe0
[ 285.471870] do_el0_svc_compat+0x1c/0x34
[ 285.472073] el0_svc_compat+0x2c/0x80
[ 285.472265] el0t_32_sync_handler+0x90/0x140
[ 285.472473] el0t_32_sync+0x19c/0x1a0
[ 285.472887] Code: f9400885 93407c23 937d7c27 11000421 (f86378a3)
[ 285.473422] ---[ end trace 0000000000000000 ]---
It reproduced simply with below script:
while [ 1 ]
do
/exportfs -r
done &
while [ 1 ]
do
insmod /nfsd.ko
mount -t nfsd none /proc/fs/nfsd
umount /proc/fs/nfsd
rmmod nfsd
done &
So exporting interfaces to user space shall be done at last and
cleanup at first place.
With change there is no Kernel OOPs.
Co-developed-by: Shubham Rana <s9.rana@samsung.com>
Signed-off-by: Shubham Rana <s9.rana@samsung.com>
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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With rpc_status netlink support, unregister of register_filesystem()
was missed in case of genl_register_family() fails.
Correcting it by making new label.
Fixes: bd9d6a3efa97 ("NFSD: add rpc_status netlink support")
Cc: stable@vger.kernel.org
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Help the client resolve the race between the reply to an
asynchronous COPY reply and the associated CB_OFFLOAD callback by
planting the session, slot, and sequence number of the COPY in the
CB_SEQUENCE contained in the CB_OFFLOAD COMPOUND.
Suggested-by: Trond Myklebust <trondmy@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The slot index number of the current COMPOUND has, until now, not
been needed outside of nfsd4_sequence(). But to record the tuple
that represents a referring call, the slot number will be needed
when processing subsequent operations in the COMPOUND.
Refactor the code that allocates a new struct nfsd4_slot to ensure
that the new sl_index field is always correctly initialized.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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We have yet to implement a mechanism in NFSD for resolving races
between a server's reply and a related callback operation. For
example, a CB_OFFLOAD callback can race with the matching COPY
response. The client will not recognize the copy state ID in the
CB_OFFLOAD callback until the COPY response arrives.
Trond adds:
> It is also needed for the same kind of race with delegation
> recalls, layout recalls, CB_NOTIFY_DEVICEID and would also be
> helpful (although not as strongly required) for CB_NOTIFY_LOCK.
RFC 8881 Section 20.9.3 describes referring call lists this way:
> The csa_referring_call_lists array is the list of COMPOUND
> requests, identified by session ID, slot ID, and sequence ID.
> These are requests that the client previously sent to the server.
> These previous requests created state that some operation(s) in
> the same CB_COMPOUND as the csa_referring_call_lists are
> identifying. A session ID is included because leased state is tied
> to a client ID, and a client ID can have multiple sessions. See
> Section 2.10.6.3.
Introduce the XDR infrastructure for populating the
csa_referring_call_lists argument of CB_SEQUENCE. Subsequent patches
will put the referring call list to use.
Note that cb_sequence_enc_sz estimates that only zero or one rcl is
included in each CB_SEQUENCE, but the new infrastructure can
manage any number of referring calls.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Try not to prolong the wait for completion of a COPY or COPY_NOTIFY
operation.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Update the status of an async COPY operation when it has been
stopped. OFFLOAD_STATUS needs to indicate that the COPY is no longer
running.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux
Pull nfsd fixes from Chuck Lever:
- v6.15 libcrc clean-up makes invalid configurations possible
- Fix a potential deadlock introduced during the v6.15 merge window
* tag 'nfsd-6.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
nfsd: decrease sc_count directly if fail to queue dl_recall
nfs: add missing selections of CONFIG_CRC32
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A deadlock warning occurred when invoking nfs4_put_stid following a failed
dl_recall queue operation:
T1 T2
nfs4_laundromat
nfs4_get_client_reaplist
nfs4_anylock_blockers
__break_lease
spin_lock // ctx->flc_lock
spin_lock // clp->cl_lock
nfs4_lockowner_has_blockers
locks_owner_has_blockers
spin_lock // flctx->flc_lock
nfsd_break_deleg_cb
nfsd_break_one_deleg
nfs4_put_stid
refcount_dec_and_lock
spin_lock // clp->cl_lock
When a file is opened, an nfs4_delegation is allocated with sc_count
initialized to 1, and the file_lease holds a reference to the delegation.
The file_lease is then associated with the file through kernel_setlease.
The disassociation is performed in nfsd4_delegreturn via the following
call chain:
nfsd4_delegreturn --> destroy_delegation --> destroy_unhashed_deleg -->
nfs4_unlock_deleg_lease --> kernel_setlease --> generic_delete_lease
The corresponding sc_count reference will be released after this
disassociation.
Since nfsd_break_one_deleg executes while holding the flc_lock, the
disassociation process becomes blocked when attempting to acquire flc_lock
in generic_delete_lease. This means:
1) sc_count in nfsd_break_one_deleg will not be decremented to 0;
2) The nfs4_put_stid called by nfsd_break_one_deleg will not attempt to
acquire cl_lock;
3) Consequently, no deadlock condition is created.
Given that sc_count in nfsd_break_one_deleg remains non-zero, we can
safely perform refcount_dec on sc_count directly. This approach
effectively avoids triggering deadlock warnings.
Fixes: 230ca758453c ("nfsd: put dl_stid if fail to queue dl_recall")
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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nfs.ko, nfsd.ko, and lockd.ko all use crc32_le(), which is available
only when CONFIG_CRC32 is enabled. But the only NFS kconfig option that
selected CONFIG_CRC32 was CONFIG_NFS_DEBUG, which is client-specific and
did not actually guard the use of crc32_le() even on the client.
The code worked around this bug by only actually calling crc32_le() when
CONFIG_CRC32 is built-in, instead hard-coding '0' in other cases. This
avoided randconfig build errors, and in real kernels the fallback code
was unlikely to be reached since CONFIG_CRC32 is 'default y'. But, this
really needs to just be done properly, especially now that I'm planning
to update CONFIG_CRC32 to not be 'default y'.
Therefore, make CONFIG_NFS_FS, CONFIG_NFSD, and CONFIG_LOCKD select
CONFIG_CRC32. Then remove the fallback code that becomes unnecessary,
as well as the selection of CONFIG_CRC32 from CONFIG_NFS_DEBUG.
Fixes: 1264a2f053a3 ("NFS: refactor code for calculating the crc32 hash of a filehandle")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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nfsd uses some VFS interfaces (such as vfs_mkdir) which take an explicit
mnt_idmap, and it passes &nop_mnt_idmap as nfsd doesn't yet support
idmapped mounts.
It also uses the lookup_one_len() family of functions which implicitly
use &nop_mnt_idmap. This mixture of implicit and explicit could be
confusing. When we eventually update nfsd to support idmap mounts it
would be best if all places which need an idmap determined from the
mount point were similar and easily found.
So this patch changes nfsd to use lookup_one(), lookup_one_unlocked(),
and lookup_one_positive_unlocked(), passing &nop_mnt_idmap.
This has the benefit of removing some uses of the lookup_one_len
functions where permission checking is actually needed. Many callers
don't care about permission checking and using these function only where
permission checking is needed is a valuable simplification.
This change requires passing the name in a qstr. Currently this is a
little clumsy, but if nfsd is changed to use qstr more broadly it will
result in a net improvement.
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/r/20250319031545.2999807-3-neil@brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Pull nfsd updates from Chuck Lever:
"Neil Brown contributed more scalability improvements to NFSD's open
file cache, and Jeff Layton contributed a menagerie of repairs to
NFSD's NFSv4 callback / backchannel implementation.
Mike Snitzer contributed a change to NFS re-export support that
disables support for file locking on a re-exported NFSv4 mount. This
is because NFSv4 state recovery is currently difficult if not
impossible for re-exported NFS mounts. The change aims to prevent data
integrity exposures after the re-export server crashes.
Work continues on the evolving NFSD netlink administrative API.
Many thanks to the contributors, reviewers, testers, and bug reporters
who participated during the v6.15 development cycle"
* tag 'nfsd-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (45 commits)
NFSD: Add a Kconfig setting to enable delegated timestamps
sysctl: Fixes nsm_local_state bounds
nfsd: use a long for the count in nfsd4_state_shrinker_count()
nfsd: remove obsolete comment from nfs4_alloc_stid
nfsd: remove unneeded forward declaration of nfsd4_mark_cb_fault()
nfsd: reorganize struct nfs4_delegation for better packing
nfsd: handle errors from rpc_call_async()
nfsd: move cb_need_restart flag into cb_flags
nfsd: replace CB_GETATTR_BUSY with NFSD4_CALLBACK_RUNNING
nfsd: eliminate cl_ra_cblist and NFSD4_CLIENT_CB_RECALL_ANY
nfsd: prevent callback tasks running concurrently
nfsd: disallow file locking and delegations for NFSv4 reexport
nfsd: filecache: drop the list_lru lock during lock gc scans
nfsd: filecache: don't repeatedly add/remove files on the lru list
nfsd: filecache: introduce NFSD_FILE_RECENT
nfsd: filecache: use list_lru_walk_node() in nfsd_file_gc()
nfsd: filecache: use nfsd_file_dispose_list() in nfsd_file_close_inode_sync()
NFSD: Re-organize nfsd_file_gc_worker()
nfsd: filecache: remove race handling.
fs: nfs: acl: Avoid -Wflex-array-member-not-at-end warning
...
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After three tries, we still see test failures with delegated
timestamps. Disable them by default, but leave the implementation
intact so that development can continue.
Cc: stable@vger.kernel.org # v6.14
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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If there are no courtesy clients then the return value from the
atomic_long_read() could overflow an int. Use a long to store the value
instead.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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idr_alloc_cyclic() is what guarantees that now, not this long-gone trick.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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This isn't needed.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Move dl_type field above dl_time, which shaves 8 bytes off this struct.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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It's possible for rpc_call_async() to fail (mainly due to memory
allocation failure). If it does, there isn't much recourse other than to
requeue the callback and try again later.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Since there is now a cb_flags word, use a new NFSD4_CALLBACK_REQUEUE
flag in that instead of a separate boolean.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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These flags serve essentially the same purpose and get set and cleared
at the same time. Drop CB_GETATTR_BUSY and just use
NFSD4_CALLBACK_RUNNING instead.
For this to work, we must use clear_and_wake_up_bit(), but doing that on
for other types of callbacks is wasteful. Declare a new NFSD4_CALLBACK_WAKE
flag in cb_flags to indicate that wake_up is needed, and only set that
for CB_GETATTRs.
Also, make the wait use a TASK_UNINTERRUPTIBLE sleep. This is done in
the context of an nfsd thread, and it should never need to deal with
signals.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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deleg_reaper() will walk the client_lru list and put any suitable
entries onto "cblist" using the cl_ra_cblist pointer. It then walks the
objects outside the spinlock and queues callbacks for them.
None of the operations that deleg_reaper() does outside the
nn->client_lock are blocking operations. Just queue their workqueue jobs
under the nn->client_lock instead.
Also, the NFSD4_CLIENT_CB_RECALL_ANY and NFSD4_CALLBACK_RUNNING flags
serve an identical purpose now. Drop the NFSD4_CLIENT_CB_RECALL_ANY flag
and just use the one in the callback.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The nfsd4_callback workqueue jobs exist to queue backchannel RPCs to
rpciod. Because they run in different workqueue contexts, the rpc_task
can run concurrently with the workqueue job itself, should it become
requeued. This is problematic as there is no locking when accessing the
fields in the nfsd4_callback.
Add a new unsigned long to nfsd4_callback and declare a new
NFSD4_CALLBACK_RUNNING flag to be set in it. When attempting to run a
workqueue job, do a test_and_set_bit() on that flag first, and don't
queue the workqueue job if it returns true. Clear NFSD4_CALLBACK_RUNNING
in nfsd41_destroy_cb().
This also gives us a more reliable mechanism for handling queueing
failures in codepaths where we have to take references under spinlocks.
We can now do the test_and_set_bit on NFSD4_CALLBACK_RUNNING first, and
only take references to the objects if that returns false.
Most of the nfsd4_run_cb() callers are converted to use this new flag or
the nfsd4_try_run_cb() wrapper. The main exception is the callback
channel probe, which has its own synchronization.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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We do not and cannot support file locking with NFS reexport over
NFSv4.x for the same reason we don't do it for NFSv3: NFS reexport
server reboot cannot allow clients to recover locks because the source
NFS server has not rebooted, and so it is not in grace. Since the
source NFS server is not in grace, it cannot offer any guarantees that
the file won't have been changed between the locks getting lost and
any attempt to recover/reclaim them. The same applies to delegations
and any associated locks, so disallow them too.
Clients are no longer allowed to get file locks or delegations from a
reexport server, any attempts will fail with operation not supported.
Update the "Reboot recovery" section accordingly in
Documentation/filesystems/nfs/reexport.rst
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Under a high NFSv3 load with lots of different files being accessed,
the LRU list of garbage-collectable files can become quite long.
Asking list_lru_scan_node() to scan the whole list can result in a long
period during which a spinlock is held, blocking the addition of new LRU
items.
So ask list_lru_scan_node() to scan only a few entries at a time, and
repeat until the scan is complete.
If the shrinker runs between two consecutive calls of
list_lru_scan_node() it could invalidate the "remaining" counter which
could lead to premature freeing. So add a spinlock to avoid that.
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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There is no need to remove a file from the lru every time we access it,
and then add it back. It is sufficient to set the REFERENCED flag every
time we put the file. The order in the lru of REFERENCED files is
largely irrelevant as they will all be moved to the end.
With this patch, files are added only when they are allocated (if
want_gc) and they are removed only by the list_lru_(shrink_)walk
callback or when forcibly removing a file.
This should reduce contention on the list_lru spinlock(s) and reduce
memory traffic a little.
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The filecache lru is walked in 2 circumstances for 2 different reasons.
1/ When called from the shrinker we want to discard the first few
entries on the list, ignoring any with NFSD_FILE_REFERENCED set
because they should really be at the end of the LRU as they have been
referenced recently. So those ones are ROTATED.
2/ When called from the nfsd_file_gc() timer function we want to discard
anything that hasn't been used since before the previous call, and
mark everything else as unused at this point in time.
Using the same flag for both of these can result in some unexpected
outcomes. If the shrinker callback clears NFSD_FILE_REFERENCED then
nfsd_file_gc() will think the file hasn't been used in a while, while
really it has.
I think it is easier to reason about the behaviour if we instead have
two flags.
NFSD_FILE_REFERENCED means "this should be at the end of the LRU, please
put it there when convenient"
NFSD_FILE_RECENT means "this has been used recently - since the last
run of nfsd_file_gc()
When either caller finds an NFSD_FILE_REFERENCED entry, that entry
should be moved to the end of the LRU and the flag cleared. This can
safely happen at any time. The actual order on the lru might not be
strictly least-recently-used, but that is normal for linux lrus.
The shrinker callback can ignore the "recent" flag. If it ends up
freeing something that is "recent" that simply means that memory
pressure is sufficient to limit the acceptable cache age to less than
the nfsd_file_gc frequency.
The gc callback should primarily focus on NFSD_FILE_RECENT. It should
free everything that doesn't have this flag set, and should clear the
flag on everything else. When it clears the flag it is convenient to
clear the "REFERENCED" flag and move to the end of the LRU too.
With this, calls from the shrinker do not prematurely age files. It
will focus only on freeing those that are least recently used.
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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list_lru_walk() is only useful when the aim is to remove all elements
from the list_lru. It will repeatedly visit rotated elements of the
first per-node sublist before proceeding to subsequent sublists.
This patch changes nfsd_file_gc() to use list_lru_walk_node() and
list_lru_count_node() on each NUMA node.
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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nfsd_file_close_inode_sync() contains an exact copy of
nfsd_file_dispose_list().
This patch removes that copy and calls nfsd_file_dispose_list()
instead.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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