Set up tracepoints to track read, write and commit, as well as
pNFS reads and writes and commits to the data server.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Set up tracepoints to track when delegations are set, reclaimed,
returned by the client, or recalled by the server.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Set up basic tracepoints for debugging NFSv4 setattr, access,
readlink, readdir, get_acl set_acl get_security_label,
and set_security_label.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Set up basic tracepoints for debugging NFSv4 lookup, unlink/remove,
symlink, mkdir, mknod, fs_locations and secinfo.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Set up basic tracepoints for debugging client id creation/destruction
and session creation/destruction.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
When doing an open of a directory, ensure that we do pass the lookup flags
from nfs_atomic_open into nfs_lookup.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.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>
Optimise for the case where we only do one lookup.
Clean up the code so it is obvious that silly[] is not a dynamic array.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
We always encode to __be32 format in XDR: silences a sparse warning.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Andy Adamson <andros@netapp.com>
Technically, we don't really need to convert these time stamps,
since they are actually cookies.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <Chuck.Lever@oracle.com>
Ever since commit 6168f62cb (Add ACCESS operation to OPEN compound)
the NFSv4 atomic open has primed the access cache, and so nfs_permission
will no longer do an RPC call on the wire.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
As per RFC 5661 Security Considerations
Commit 4edaa308 "NFS: Use "krb5i" to establish NFSv4 state whenever possible"
uses the nfs_client cl_rpcclient for all clientid management operations.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
As per RFC 3530 and RFC 5661 Security Considerations
Commit 4edaa308 "NFS: Use "krb5i" to establish NFSv4 state whenever possible"
uses the nfs_client cl_rpcclient for all clientid management operations.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Increase NFS4_DEF_SLOT_TABLE_SIZE which is used as the client ca_maxreequests
value in CREATE_SESSION. Current non-dynamic session slot server
implementations use the client ca_maxrequests as a maximum slot number: 64
session slots can handle most workloads.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Never try to use a non-UID 0 user credential for lease management,
as that credential can change out from under us. The server will
block NFSv4 lease recovery with NFS4ERR_CLID_INUSE.
Since the mechanism to acquire a credential for lease management
is now the same for all minor versions, replace the minor version-
specific callout with a single function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Commit 05f4c350 "NFS: Discover NFSv4 server trunking when mounting"
Fri Sep 14 17:24:32 2012 introduced Uniform Client String support,
which forces our NFS client to establish a client ID immediately
during a mount operation rather than waiting until a user wants to
open a file.
Normally machine credentials (eg. from a keytab) are used to perform
a mount operation that is protected by Kerberos. Before 05fc350,
SETCLIENTID used a machine credential, or fell back to a regular
user's credential if no keytab is available.
On clients that don't have a keytab, performing SETCLIENTID early
means there's no user credential to fall back on, since no regular
user has kinit'd yet. 05f4c350 seems to have broken the ability
to mount with sec=krb5 on clients that don't have a keytab in
kernels 3.7 - 3.10.
To address this regression, commit 4edaa308 (NFS: Use "krb5i" to
establish NFSv4 state whenever possible), Sat Mar 16 15:56:20 2013,
was merged in 3.10. This commit forces the NFS client to fall back
to AUTH_SYS for lease management operations if no keytab is
available.
Neil Brown noticed that, since root is required to kinit to do a
sec=krb5 mount when a client doesn't have a keytab, we can try to
use root's Kerberos credential before AUTH_SYS.
Now, when determining a principal and flavor to use for lease
management, the NFS client tries in this order:
1. Flavor: AUTH_GSS, krb5i
Principal: service principal (via keytab)
2. Flavor: AUTH_GSS, krb5i
Principal: user principal established for UID 0 (via kinit)
3. Flavor: AUTH_SYS
Principal: UID 0 / GID 0
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Currently, you can open a NFSv4 file with O_APPEND|O_DIRECT, but cannot
fcntl(F_SETFL,...) with those flags. This flag combination is explicitly
forbidden on NFSv3 opens, and it seems like it should also be on NFSv4.
Reported-by: Chao Ye <cye@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Commit 6f2ea7f2a (NFS: Add nfs4_unique_id boot parameter) introduces a
boot parameter that allows client administrators to set a string
identifier for use by the EXCHANGE_ID and SETCLIENTID arguments in order
to make them more globally unique.
Unfortunately, that uniquifier is no longer globally unique in the presence
of net namespaces, since each container expects to be able to set up their
own lease when mounting a new NFSv4/4.1 partition.
The fix is to add back in the container-specific hostname in addition to
the unique id.
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Should not use the clientid maintenance rpc_clnt.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: when NFSv4.1 support is compiled out,
nfs4_end_drain_session() becomes a stub. Make the synopsis of the
stub match the synopsis of the real version of the function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Now that Al has fixed simple_lookup to account for the case where
sb->s_d_op is set, there's no need to keep our own special lookup op.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
nfs4_proc_setattr removes ATTR_OPEN from sattr->ia_valid, but later
nfs4_do_setattr checks for it
Signed-off-by: Nadav Shemer <nadav@tonian.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
The attribute length is already calculated in advance. There is no
reason why we cannot calculate the bitmap in advance too so that
we don't have to play pointer games.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Pull alpha architecture fixes from Matt Turner:
"This contains mostly clean ups and fixes but also an implementation of
atomic64_dec_if_positive() and a pair of new syscalls"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha:
alpha: Use handle_percpu_irq for the timer interrupt
alpha: Force the user-visible HZ to a constant 1024.
alpha: Don't if-out dp264_device_interrupt.
alpha: Use __builtin_alpha_rpcc
alpha: Fix type compatibility warning for marvel_map_irq
alpha: Generate dwarf2 unwind info for various kernel entry points.
alpha: Implement atomic64_dec_if_positive
alpha: Improve atomic_add_unless
alpha: Modernize lib/mpi/longlong.h
alpha: Add kcmp and finit_module syscalls
alpha: locks: remove unused arch_*_relax operations
alpha: kernel: typo issue, using '1' instead of '11'
alpha: kernel: using memcpy() instead of strcpy()
alpha: Convert print_symbol to %pSR
This includes some fixes for vhost net and scsi drivers.
The test module has already been reworked to avoid rcu
usage, but the necessary core changes are missing,
we fixed this.
Unlikely to affect any real-world users, but it's
early in the cycle so, let's merge them.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.13 (GNU/Linux)
iQEcBAABAgAGBQJR3qu5AAoJECgfDbjSjVRp66UIAKZFjSnjWBhQbqI+LkrrUJ+H
Zv4xnEgTU+5k7zLpArqhDABbWMPVUSHm91ecjS/OX9WWsXVYG2jAT+PK6F3PrexK
BpUA3RDX8a5drXleidhwGf2dHmsBhTTwZyn31h/pvKAiM27kVjFOS0S9Rhnpu/0x
UI/z/s//CZ/kNKbCvYVqu0+KjbrwDiRD1N56hGDLqwsVoFIn1sP9CBIg/PHCqebK
GnPSidTFdRu4yvFvhwJqQ3RgfpCxbgBc619knWr8XX4PVoH25NdpLZ4yHrR58Ms0
Hb2IJ5q9bOGf0hbLFKOeHO29uVyOtTGGq0UG7NnfS1aToIT/Zw2kYICV5kBlSvs=
=XGuu
-----END PGP SIGNATURE-----
Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
Pull vhost fixes from Michael Tsirkin:
"vhost: more fixes for 3.11
This includes some fixes for vhost net and scsi drivers.
The test module has already been reworked to avoid rcu usage, but the
necessary core changes are missing, we fixed this.
Unlikely to affect any real-world users, but it's early in the cycle
so, let's merge them"
(It was earlier when Michael originally sent the email, but it somehot
got missed in the flood, so here it is after -rc2)
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
vhost: Remove custom vhost rcu usage
vhost-scsi: Always access vq->private_data under vq mutex
vhost-net: Always access vq->private_data under vq mutex
The calculation of the attribute length was 4 bytes off.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Tested-by: Andre Heider <a.heider@gmail.com>
Reported-and-tested-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some of the fixes need to go back to 3.10. They are minor, and deal mostly
with incorrect ref counting in accessing event files.
There was a couple of optimizations that should have perf perform a bit
better when accessing trace events.
And some various clean ups. Some of the clean ups are necessary to help
in a fix to a theoretical race between opening a event file and
deleting that event.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)
iQEcBAABAgAGBQJR7TuSAAoJEOdOSU1xswtMFsEIALOQWth+jUEmd+TJNMgW7vHd
aJ4pjc0Br2ur0XOm4xsOOsuexQ/sKG4J0qJT4z01Ny4ZJ6UcL6CvLKlQXlySrUw5
POH6+7B7os3ikav+4KGDYJpeyR7l+uveA7IcqZz5OWAbz2yi3HbluPUUyFn+62ic
Q0IOi4KkCly4buHNqJqfQRUo+0eBb8sZUfaklIQE07Dd66YVyq4w2WogI2PxBanP
b6p4sE9n7wf7GxXXur5jPBz8PheAFu6a6dM9d9BX28ia79OGSGN4mYWbSNOn8wzl
gJr1ZqxKJBq73IHpNV7QBOCCgDJ9vtuqxKKm4kuLCMfjCTPBsQ3Bmo/qJulnnGI=
=AlmI
-----END PGP SIGNATURE-----
Merge tag 'trace-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes and cleanups from Steven Rostedt:
"This contains fixes, optimizations and some clean ups
Some of the fixes need to go back to 3.10. They are minor, and deal
mostly with incorrect ref counting in accessing event files.
There was a couple of optimizations that should have perf perform a
bit better when accessing trace events.
And some various clean ups. Some of the clean ups are necessary to
help in a fix to a theoretical race between opening a event file and
deleting that event"
* tag 'trace-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Kill the unbalanced tr->ref++ in tracing_buffers_open()
tracing: Kill trace_array->waiter
tracing: Do not (ab)use trace_seq in event_id_read()
tracing: Simplify the iteration logic in f_start/f_next
tracing: Add ref_data to function and fgraph tracer structs
tracing: Miscellaneous fixes for trace_array ref counting
tracing: Fix error handling to ensure instances can always be removed
tracing/kprobe: Wait for disabling all running kprobe handlers
tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare()
tracing/syscall: Avoid perf_trace_buf_*() if sys_data->perf_events is empty
tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is empty
tracing: Typo fix on ring buffer comments
tracing: Use trace_seq_puts()/trace_seq_putc() where possible
tracing: Use correct config guard CONFIG_STACK_TRACER
Pull thermal management fixes from Zhang Rui:
"These are fixes collected over the last week, they fixes several
problems caused by the x86_pkg_temp_thermal introduced in 3.11-rc1.
Specifics:
- the x86_pkg_temp_thermal driver causes crash on systems with no
package MSR support as there is a bug in the logic to check
presence of DTHERM and PTS feature together. Added a change so
that when there is no PTS support, module doesn't get loaded.
- fix krealloc() misuse in pkg_temp_thermal_device_add().
If krealloc() returns NULL, it doesn't free the original. Thus if
we want to exit because of the krealloc() failure, we must make
sure the original one is freed.
- The error code path of the x86 package temperature thermal driver's
initialization routine makes an unbalanced call to
get_online_cpus(), which causes subsequent CPU offline operations,
and consequently system suspend, to permanently block in
cpu_hotplug_begin() on systems where get_core_online() returns an
error code.
Remove the extra get_online_cpus() to fix the problem"
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux:
Thermal: Fix lockup of cpu_down()
Thermal: x86_pkg_temp: Limit number of pkg temp zones
Thermal: x86_pkg_temp: fix krealloc() misuse in in pkg_temp_thermal_device_add()
Thermal: x86 package temp thermal crash
- OMAP device tree boot fix
- Handle an error condition in the MSM driver
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.13 (GNU/Linux)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=Ld25
-----END PGP SIGNATURE-----
Merge tag 'gpio-for-v3.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio
Pull gpio fixes from Linus Walleij:
"A first round of GPIO fixes for the v3.11 series:
- OMAP device tree boot fix
- Handle an error condition in the MSM driver
The OMAP patches have been around since around the merge window, but
since they first caused more breakage I let them boil in -next for a
while. These should be fine now"
* tag 'gpio-for-v3.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
drivers: gpio: msm: Fix the error condition for reading ngpio
gpio/omap: fix build error when OF_GPIO is not defined.
gpio/omap: auto request GPIO as input if used as IRQ via DT
gpio/omap: don't create an IRQ mapping for every GPIO on DT
Pull block IO driver bits from Jens Axboe:
"As I mentioned in the core block pull request, due to real life
circumstances the driver pull request would be late. Now it looks
like -rc2 late... On the plus side, apart form the rsxx update, these
are all things that I could argue could go in later in the cycle as
they are fixes and not features. So even though things are late, it's
not ALL bad.
The pull request contains:
- Updates to bcache, all bug fixes, from Kent.
- A pile of drbd bug fixes (no big features this time!).
- xen blk front/back fixes.
- rsxx driver updates, some of them deferred form 3.10. So should be
well cooked by now"
* 'for-3.11/drivers' of git://git.kernel.dk/linux-block: (63 commits)
bcache: Allocation kthread fixes
bcache: Fix GC_SECTORS_USED() calculation
bcache: Journal replay fix
bcache: Shutdown fix
bcache: Fix a sysfs splat on shutdown
bcache: Advertise that flushes are supported
bcache: check for allocation failures
bcache: Fix a dumb race
bcache: Use standard utility code
bcache: Update email address
bcache: Delete fuzz tester
bcache: Document shrinker reserve better
bcache: FUA fixes
drbd: Allow online change of al-stripes and al-stripe-size
drbd: Constants should be UPPERCASE
drbd: Ignore the exit code of a fence-peer handler if it returns too late
drbd: Fix rcu_read_lock balance on error path
drbd: fix error return code in drbd_init()
drbd: Do not sleep inside rcu
bcache: Refresh usage docs
...
Commit f1a18a105 "Thermal: CPU Package temperature thermal" had code
that did a get_online_cpus(), run a loop and then do a
put_online_cpus(). The problem is that the loop had an error exit that
would skip the put_online_cpus() part.
In the error exit part of the function, it also did a get_online_cpus(),
run a loop and then put_online_cpus(). The only way to get to the error
exit part is with get_online_cpus() already performed. If this error
condition is hit, the system will be prevented from taking CPUs offline.
The process taking the CPU offline will lock up hard.
Removing the get_online_cpus() removes the lockup as the hotplug CPU
refcount is back to zero.
This was bisected with ktest.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
- Change from Aaron Lu makes ACPICA export a variable which can be
used by driver code to determine whether or not the BIOS believes
that we are compatible with Windows 8.
- Change from Matthew Garrett makes the ACPI video driver initialize
the ACPI backlight even if it is not going to be used afterward
(that is needed for backlight control to work on Thinkpads).
- Fix from Rafael J Wysocki implements Windows 8 backlight support
workaround making i915 take over bakclight control if the firmware
thinks it's dealing with Windows 8. Based on the work of multiple
developers including Matthew Garrett, Chun-Yi Lee, Seth Forshee,
and Aaron Lu.
- Fix from Aaron Lu makes the kernel follow Windows 8 by informing
the firmware through the _DOS method that it should not carry out
automatic brightness changes, so that brightness can be controlled
by GUI.
/
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.19 (GNU/Linux)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=vlwF
-----END PGP SIGNATURE-----
Merge tag 'acpi-video-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI video support fixes from Rafael Wysocki:
"I'm sending a separate pull request for this as it may be somewhat
controversial. The breakage addressed here is not really new and the
fixes may not satisfy all users of the affected systems, but we've had
so much back and forth dance in this area over the last several weeks
that I think it's time to actually make some progress.
The source of the problem is that about a year ago we started to tell
BIOSes that we're compatible with Windows 8, which we really need to
do, because some systems shipping with Windows 8 are tested with it
and nothing else, so if we tell their BIOSes that we aren't compatible
with Windows 8, we expose our users to untested BIOS/AML code paths.
However, as it turns out, some Windows 8-specific AML code paths are
not tested either, because Windows 8 actually doesn't use the ACPI
methods containing them, so if we declare Windows 8 compatibility and
attempt to use those ACPI methods, things break. That occurs mostly
in the backlight support area where in particular the _BCM and _BQC
methods are plain unusable on some systems if the OS declares Windows
8 compatibility.
[ The additional twist is that they actually become usable if the OS
says it is not compatible with Windows 8, but that may cause
problems to show up elsewhere ]
Investigation carried out by Matthew Garrett indicates that what
Windows 8 does about backlight is to leave backlight control up to
individual graphics drivers. At least there's evidence that it does
that if the Intel graphics driver is used, so we've decided to follow
Windows 8 in that respect and allow i915 to control backlight (Daniel
likes that part).
The first commit from Aaron Lu makes ACPICA export the variable from
which we can infer whether or not the BIOS believes that we are
compatible with Windows 8.
The second commit from Matthew Garrett prepares the ACPI video driver
by making it initialize the ACPI backlight even if it is not going to
be used afterward (that is needed for backlight control to work on
Thinkpads).
The third commit implements the actual workaround making i915 take
over backlight control if the firmware thinks it's dealing with
Windows 8 and is based on the work of multiple developers, including
Matthew Garrett, Chun-Yi Lee, Seth Forshee, and Aaron Lu.
The final commit from Aaron Lu makes us follow Windows 8 by informing
the firmware through the _DOS method that it should not carry out
automatic brightness changes, so that brightness can be controlled by
GUI.
Hopefully, this approach will allow us to avoid using blacklists of
systems that should not declare Windows 8 compatibility just to avoid
backlight control problems in the future.
- Change from Aaron Lu makes ACPICA export a variable which can be
used by driver code to determine whether or not the BIOS believes
that we are compatible with Windows 8.
- Change from Matthew Garrett makes the ACPI video driver initialize
the ACPI backlight even if it is not going to be used afterward
(that is needed for backlight control to work on Thinkpads).
- Fix from Rafael J Wysocki implements Windows 8 backlight support
workaround making i915 take over bakclight control if the firmware
thinks it's dealing with Windows 8. Based on the work of multiple
developers including Matthew Garrett, Chun-Yi Lee, Seth Forshee,
and Aaron Lu.
- Fix from Aaron Lu makes the kernel follow Windows 8 by informing
the firmware through the _DOS method that it should not carry out
automatic brightness changes, so that brightness can be controlled
by GUI"
* tag 'acpi-video-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI / video: no automatic brightness changes by win8-compatible firmware
ACPI / video / i915: No ACPI backlight if firmware expects Windows 8
ACPI / video: Always call acpi_video_init_brightness() on init
ACPICA: expose OSI version
