Tools like tcpdump and rpcdebug can be very useful. But there are
plenty of environments where they are difficult or impossible to
use. For example, we've had customers report I/O failures during
workloads so heavy that collecting network traffic or enabling
RPC debugging are themselves onerous.
The kernel's static tracepoints are lightweight (less likely to
introduce timing changes) and efficient (the trace data is compact).
They also work in scenarios where capturing network traffic is not
possible due to lack of hardware support (some InfiniBand HCAs) or
where data or network privacy is a concern.
Introduce tracepoints that show when an NFS READ, WRITE, or COMMIT
is initiated, and when it completes. Record the arguments and
results of each operation, which are not shown by existing sunrpc
module's tracepoints.
For instance, the recorded offset and count can be used to match an
"initiate" event to a "done" event. If an NFS READ result returns
fewer bytes than requested or zero, seeing the EOF flag can be
probative. Seeing an NFS4ERR_BAD_STATEID result is also indication
of a particular class of problems. The timing information attached
to each event record can often be useful as well.
Usage example:
[root@manet tmp]# trace-cmd record -e nfs:*initiate* -e nfs:*done
/sys/kernel/debug/tracing/events/nfs/*initiate*/filter
/sys/kernel/debug/tracing/events/nfs/*done/filter
Hit Ctrl^C to stop recording
^CKernel buffer statistics:
Note: "entries" are the entries left in the kernel ring buffer and are not
recorded in the trace data. They should all be zero.
CPU: 0
entries: 0
overrun: 0
commit overrun: 0
bytes: 3680
oldest event ts: 78.367422
now ts: 100.124419
dropped events: 0
read events: 74
... and so on.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Highlights include:
Stable bugfixes:
- nfs: don't create zero-length requests
- Several LAYOUTGET bugfixes
Features:
- Several performance related features
- More aggressive caching when we can rely on close-to-open cache
consistency
- Remove serialisation of O_DIRECT reads and writes
- Optimise several code paths to not flush to disk unnecessarily. However
allow for the idiosyncracies of pNFS for those layout types that need
to issue a LAYOUTCOMMIT before the metadata can be updated on the server.
- SUNRPC updates to the client data receive path
- pNFS/SCSI support RH/Fedora dm-mpath device nodes
- pNFS files/flexfiles can now use unprivileged ports when the generic NFS
mount options allow it.
Bugfixes:
- Don't use RDMA direct data placement together with data integrity or
privacy security flavours
- Remove the RDMA ALLPHYSICAL memory registration mode as it has potential
security holes.
- Several layout recall fixes to improve NFSv4.1 protocol compliance.
- Fix an Oops in the pNFS files and flexfiles connection setup to the DS
- Allow retry of operations that used a returned delegation stateid
- Don't mark the inode as revalidated if a LAYOUTCOMMIT is outstanding
- Fix writeback races in nfs4_copy_range() and nfs42_proc_deallocate()
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1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=WNyE
-----END PGP SIGNATURE-----
Merge tag 'nfs-for-4.8-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
Pull NFS client updates from Trond Myklebust:
"Highlights include:
Stable bugfixes:
- nfs: don't create zero-length requests
- several LAYOUTGET bugfixes
Features:
- several performance related features
- more aggressive caching when we can rely on close-to-open
cache consistency
- remove serialisation of O_DIRECT reads and writes
- optimise several code paths to not flush to disk unnecessarily.
However allow for the idiosyncracies of pNFS for those layout
types that need to issue a LAYOUTCOMMIT before the metadata can
be updated on the server.
- SUNRPC updates to the client data receive path
- pNFS/SCSI support RH/Fedora dm-mpath device nodes
- pNFS files/flexfiles can now use unprivileged ports when
the generic NFS mount options allow it.
Bugfixes:
- Don't use RDMA direct data placement together with data
integrity or privacy security flavours
- Remove the RDMA ALLPHYSICAL memory registration mode as
it has potential security holes.
- Several layout recall fixes to improve NFSv4.1 protocol
compliance.
- Fix an Oops in the pNFS files and flexfiles connection
setup to the DS
- Allow retry of operations that used a returned delegation
stateid
- Don't mark the inode as revalidated if a LAYOUTCOMMIT is
outstanding
- Fix writeback races in nfs4_copy_range() and
nfs42_proc_deallocate()"
* tag 'nfs-for-4.8-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (104 commits)
pNFS: Actively set attributes as invalid if LAYOUTCOMMIT is outstanding
NFSv4: Clean up lookup of SECINFO_NO_NAME
NFSv4.2: Fix warning "variable ‘stateids’ set but not used"
NFSv4: Fix warning "no previous prototype for ‘nfs4_listxattr’"
SUNRPC: Fix a compiler warning in fs/nfs/clnt.c
pNFS: Remove redundant smp_mb() from pnfs_init_lseg()
pNFS: Cleanup - do layout segment initialisation in one place
pNFS: Remove redundant stateid invalidation
pNFS: Remove redundant pnfs_mark_layout_returned_if_empty()
pNFS: Clear the layout metadata if the server changed the layout stateid
pNFS: Cleanup - don't open code pnfs_mark_layout_stateid_invalid()
NFS: pnfs_mark_matching_lsegs_return() should match the layout sequence id
pNFS: Do not set plh_return_seq for non-callback related layoutreturns
pNFS: Ensure layoutreturn acts as a completion for layout callbacks
pNFS: Fix CB_LAYOUTRECALL stateid verification
pNFS: Always update the layout barrier seqid on LAYOUTGET
pNFS: Always update the layout stateid if NFS_LAYOUT_INVALID_STID is set
pNFS: Clear the layout return tracking on layout reinitialisation
pNFS: LAYOUTRETURN should only update the stateid if the layout is valid
nfs: don't create zero-length requests
...
Use __get_str(str) rather than __get_dynamic_array(str) when
deadling with strings.
It is just a code cleanup, no changes on tracepoint ABI.
Link: http://lkml.kernel.org/r/ea260df91817411cca2a1f3db2abd88860094788.1467407618.git.bristot@redhat.com
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Anna Schumaker <anna.schumaker@netapp.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-nfs@vger.kernel.org
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
use d_alloc_parallel() for sillyunlink/lookup exclusion and
explicit rwsem (nfs_rmdir() being a writer and nfs_call_unlink() -
a reader) for rmdir/sillyunlink one.
That ought to make lookup/readdir/!O_CREAT atomic_open really
parallel on NFS.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Allow synchronous RPC calls to wait for pending RPC calls to finish,
but also allow asynchronous ones to just fire off another commit.
With this patch, the xfstests generic/074 test completes in 226s
instead of 242s
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
There is a possible race in how the nfs_invalidate_mapping function is
handled. Currently, we go and invalidate the pages in the file and then
clear NFS_INO_INVALID_DATA.
The problem is that it's possible for a stale page to creep into the
mapping after the page was invalidated (i.e., via readahead). If another
writer comes along and sets the flag after that happens but before
invalidate_inode_pages2 returns then we could clear the flag
without the cache having been properly invalidated.
So, we must clear the flag first and then invalidate the pages. Doing
this however, opens another race:
It's possible to have two concurrent read() calls that end up in
nfs_revalidate_mapping at the same time. The first one clears the
NFS_INO_INVALID_DATA flag and then goes to call nfs_invalidate_mapping.
Just before calling that though, the other task races in, checks the
flag and finds it cleared. At that point, it trusts that the mapping is
good and gets the lock on the page, allowing the read() to be satisfied
from the cache even though the data is no longer valid.
These effects are easily manifested by running diotest3 from the LTP
test suite on NFS. That program does a series of DIO writes and buffered
reads. The operations are serialized and page-aligned but the existing
code fails the test since it occasionally allows a read to come out of
the cache incorrectly. While mixing direct and buffered I/O isn't
recommended, I believe it's possible to hit this in other ways that just
use buffered I/O, though that situation is much harder to reproduce.
The problem is that the checking/clearing of that flag and the
invalidation of the mapping really need to be atomic. Fix this by
serializing concurrent invalidations with a bitlock.
At the same time, we also need to allow other places that check
NFS_INO_INVALID_DATA to check whether we might be in the middle of
invalidating the file, so fix up a couple of places that do that
to look for the new NFS_INO_INVALIDATING flag.
Doing this requires us to be careful not to set the bitlock
unnecessarily, so this code only does that if it believes it will
be doing an invalidation.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Add tracepoints for inode attribute updates, attribute revalidation,
writeback start/end fsync start/end, attribute change start/end,
permission check start/end.
The intention is to enable performance tracing using 'perf'as well as
improving debugging.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever