Peng Tao [Thu, 23 Aug 2012 16:27:53 +0000 (00:27 +0800)]
pnfsblock: fix non-aligned DIO write
For DIO writes, if it is not blocksize aligned, we need to do
internal serialization. It may slow down writers anyway. So we
just bail them out and resend to MDS.
Peng Tao [Thu, 23 Aug 2012 16:27:52 +0000 (00:27 +0800)]
pnfsblock: fix non-aligned DIO read
For DIO read, if it is not sector aligned, we should reject it
and resend via MDS. Otherwise there might be data corruption.
Also teach bl_read_pagelist to handle partial page reads for DIO.
Peng Tao [Thu, 23 Aug 2012 16:27:51 +0000 (00:27 +0800)]
pnfsblock: fix partial page buffer wirte
If applications use flock to protect its write range, generic NFS
will not do read-modify-write cycle at page cache level. Therefore
LD should know how to handle non-sector aligned writes. Otherwise
there will be data corruption.
Peng Tao [Thu, 23 Aug 2012 16:27:49 +0000 (00:27 +0800)]
NFS41: fix error of setting blocklayoutdriver
After commit e38eb650 (NFS: set_pnfs_layoutdriver() from
nfs4_proc_fsinfo()), set_pnfs_layoutdriver() is called inside
nfs4_proc_fsinfo(), but pnfs_blksize is not set. It causes setting
blocklayoutdriver failure and pnfsblock mount failure.
Peng Tao [Thu, 23 Aug 2012 16:27:48 +0000 (00:27 +0800)]
NFSv41: fix DIO write_io calculation
pnfs_within_mdsthreshold() is called inside pg_init. We need to set
read_io/write_io before that. Otherwise we fail pnfs_within_mdsthreshold()
and IO goes to MDS.
A simple test case:
dd if=foo of=/mnt/pnfs/bar bs=10M count=1 oflag=direct
Signed-off-by: Peng Tao <tao.peng@emc.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:24:41 +0000 (17:24 -0400)]
NFS: Add nfs4_unique_id boot parameter
An optional boot parameter is introduced to allow client
administrators to specify a string that the Linux NFS client can
insert into its nfs_client_id4 id string, to make it both more
globally unique, and to ensure that it doesn't change even if the
client's nodename changes.
If this boot parameter is not specified, the client's nodename is
used, as before.
Client installation procedures can create a unique string (typically,
a UUID) which remains unchanged during the lifetime of that client
instance. This works just like creating a UUID for the label of the
system's root and boot volumes.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:24:32 +0000 (17:24 -0400)]
NFS: Discover NFSv4 server trunking when mounting
"Server trunking" is a fancy named for a multi-homed NFS server.
Trunking might occur if a client sends NFS requests for a single
workload to multiple network interfaces on the same server. There
are some implications for NFSv4 state management that make it useful
for a client to know if a single NFSv4 server instance is
multi-homed. (Note this is only a consideration for NFSv4, not for
legacy versions of NFS, which are stateless).
If a client cares about server trunking, no NFSv4 operations can
proceed until that client determines who it is talking to. Thus
server IP trunking discovery must be done when the client first
encounters an unfamiliar server IP address.
The nfs_get_client() function walks the nfs_client_list and matches
on server IP address. The outcome of that walk tells us immediately
if we have an unfamiliar server IP address. It invokes
nfs_init_client() in this case. Thus, nfs4_init_client() is a good
spot to perform trunking discovery.
Discovery requires a client to establish a fresh client ID, so our
client will now send SETCLIENTID or EXCHANGE_ID as the first NFS
operation after a successful ping, rather than waiting for an
application to perform an operation that requires NFSv4 state.
The exact process for detecting trunking is different for NFSv4.0 and
NFSv4.1, so a minorversion-specific init_client callout method is
introduced.
CLID_INUSE recovery is important for the trunking discovery process.
CLID_INUSE is a sign the server recognizes the client's nfs_client_id4
id string, but the client is using the wrong principal this time for
the SETCLIENTID operation. The SETCLIENTID must be retried with a
series of different principals until one works, and then the rest of
trunking discovery can proceed.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:24:21 +0000 (17:24 -0400)]
NFS: Use the same nfs_client_id4 for every server
Currently, when identifying itself to NFS servers, the Linux NFS
client uses a unique nfs_client_id4.id string for each server IP
address it talks with. For example, when client A talks to server X,
the client identifies itself using a string like "AX". The
requirements for these strings are specified in detail by RFC 3530
(and bis).
This form of client identification presents a problem for Transparent
State Migration. When client A's state on server X is migrated to
server Y, it continues to be associated with string "AX." But,
according to the rules of client string construction above, client
A will present string "AY" when communicating with server Y.
Server Y thus has no way to know that client A should be associated
with the state migrated from server X. "AX" is all but abandoned,
interfering with establishing fresh state for client A on server Y.
To support transparent state migration, then, NFSv4.0 clients must
instead use the same nfs_client_id4.id string to identify themselves
to every NFS server; something like "A".
Now a client identifies itself as "A" to server X. When a file
system on server X transitions to server Y, and client A identifies
itself as "A" to server Y, Y will know immediately that the state
associated with "A," whether it is native or migrated, is owned by
the client, and can merge both into a single lease.
As a pre-requisite to adding support for NFSv4 migration to the Linux
NFS client, this patch changes the way Linux identifies itself to NFS
servers via the SETCLIENTID (NFSv4 minor version 0) and EXCHANGE_ID
(NFSv4 minor version 1) operations.
In addition to removing the server's IP address from nfs_client_id4,
the Linux NFS client will also no longer use its own source IP address
as part of the nfs_client_id4 string. On multi-homed clients, the
value of this address depends on the address family and network
routing used to contact the server, thus it can be different for each
server.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:24:11 +0000 (17:24 -0400)]
NFS: Introduce "migration" mount option
Currently, the Linux client uses a unique nfs_client_id4.id string
when identifying itself to distinct NFS servers.
To support transparent state migration, the Linux client will have to
use the same nfs_client_id4 string for all servers it communicates
with (also known as the "uniform client string" approach). Otherwise
NFS servers can not recognize that open and lock state need to be
merged after a file system transition.
Unfortunately, there are some NFSv4.0 servers currently in the field
that do not tolerate the uniform client string approach.
Thus, by default, our NFSv4.0 mounts will continue to use the current
approach, and we introduce a mount option that switches them to use
the uniform model. Client administrators must identify which servers
can be mounted with this option. Eventually most NFSv4.0 servers will
be able to handle the uniform approach, and we can change the default.
The first mount of a server controls the behavior for all subsequent
mounts for the lifetime of that set of mounts of that server. After
the last mount of that server is gone, the client erases the data
structure that tracks the lease. A subsequent lease may then honor
a different "migration" setting.
This patch adds only the infrastructure for parsing the new mount
option. Support for uniform client strings is added in a subsequent
patch.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:24:02 +0000 (17:24 -0400)]
SUNRPC: Introduce rpc_clone_client_set_auth()
An ULP is supposed to be able to replace a GSS rpc_auth object with
another GSS rpc_auth object using rpcauth_create(). However,
rpcauth_create() in 3.5 reliably fails with -EEXIST in this case.
This is because when gss_create() attempts to create the upcall pipes,
sometimes they are already there. For example if a pipe FS mount
event occurs, or a previous GSS flavor was in use for this rpc_clnt.
It turns out that's not the only problem here. While working on a
fix for the above problem, we noticed that replacing an rpc_clnt's
rpc_auth is not safe, since dereferencing the cl_auth field is not
protected in any way.
So we're deprecating the ability of rpcauth_create() to switch an
rpc_clnt's security flavor during normal operation. Instead, let's
add a fresh API that clones an rpc_clnt and gives the clone a new
flavor before it's used.
This makes immediate use of the new __rpc_clone_client() helper.
This can be used in a similar fashion to rpcauth_create() when a
client is hunting for the correct security flavor. Instead of
replacing an rpc_clnt's security flavor in a loop, the ULP replaces
the whole rpc_clnt.
To fix the -EEXIST problem, any ULP logic that relies on replacing
an rpc_clnt's rpc_auth with rpcauth_create() must be changed to use
this API instead.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:23:52 +0000 (17:23 -0400)]
SUNRPC: Refactor rpc_clone_client()
rpc_clone_client() does most of the same tasks as rpc_new_client(),
so there is an opportunity for code re-use. Create a generic helper
that makes it easy to clone an RPC client while replacing any of the
clnt's parameters.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:23:43 +0000 (17:23 -0400)]
SUNRPC: Use __func__ in dprintk() in auth_gss.c
Clean up: Some function names have changed, but debugging messages
were never updated. Automate the construction of the function name
in debugging messages.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:23:23 +0000 (17:23 -0400)]
NFS: Slow down state manager after an unhandled error
If the state manager thread is not actually able to fully recover from
some situation, it wakes up waiters, who kick off a new state manager
thread. Quite often the fresh invocation of the state manager is just
as successful.
This results in a livelock as the client dumps thousands of NFS
requests a second on the network in a vain attempt to recover. Not
very friendly.
To mitigate this situation, add a delay in the state manager after
an unhandled error, so that the client sends just a few requests
every second in this case.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Chuck Lever [Fri, 14 Sep 2012 21:23:14 +0000 (17:23 -0400)]
NFS: nfs_parsed_mount_options can use unsigned int
fs/nfs/super.c: In function ‘nfs_compare_remount_data’:
fs/nfs/super.c:2042:18: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
fs/nfs/super.c:2043:18: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
fs/nfs/super.c:2044:20: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
fs/nfs/super.c:2046:21: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
fs/nfs/super.c:2047:21: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
fs/nfs/super.c:2048:21: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
fs/nfs/super.c:2049:21: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
fs/nfs/super.c:2050:18: warning: comparison between signed and
unsigned integer expressions [-Wsign-compare]
Seen with gcc (GCC) 4.6.3 20120306 (Red Hat 4.6.3-2).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
lockd: create and use per-net NSM RPC clients on MON/UNMON requests
NSM RPC client can be required on NFSv3 umount, when child reaper is dying
(and destroying it's mount namespace). It means, that current nsproxy is set
to NULL already, but creation of RPC client requires UTS namespace for gaining
hostname string.
This patch creates reference-counted per-net NSM client on first monitor
request and destroys it after last unmonitor request.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: <stable@vger.kernel.org> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
lockd: use rpc client's cl_nodename for id encoding
Taking hostname from uts namespace if not safe, because this cuold be
performind during umount operation on child reaper death. And in this case
current->nsproxy is NULL already.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: <stable@vger.kernel.org> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
lockd: per-net NSM client creation and destruction helpers introduced
NSM RPC client can be required on NFSv3 umount, when child reaper is dying (and
destroying it's mount namespace). It means, that current nsproxy is set to
NULL already, but creation of RPC client requires UTS namespace for gaining
hostname string.
This patch introduces reference counted NFS RPC clients creation and
destruction helpers (similar to RPCBIND RPC clients).
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: <stable@vger.kernel.org> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Usage coutner now increased only is the service was started sccessfully.
Even if service is running already, then goto is not required anymore, because
service creation and start will be skipped.
With this patch code looks clearer.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This is just a code move, which from my POW makes code looks better.
I.e. now on start we have 3 different stages:
1) Service creation.
2) Service per-net data allocation.
3) Service start.
Patch also renames goto label "out_err:" into "err_start:" to reflect new
changes.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
No need to assign transports backchannel server explicitly in
nfs41_callback_up() - there is nfs_callback_bc_serv() function for this.
By using it, nfs4_callback_up() and nfs41_callback_up() can be called without
transport argument.
Note: service have to be passed to nfs_callback_bc_serv() instead of callback,
since callback link can be uninitialized.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFS: move per-net callback thread initialization to nfs_callback_up_net()
v4:
1) Callback transport creation routine selection by version simlified.
This new function in now called before nfs_minorversion_callback_svc_setup()).
Also few small changes:
1) current network namespace in nfs_callback_up() was replaced by transport net.
2) svc_shutdown_net() was moved prior to callback usage counter decrement
(because in case of per-net data allocation faulure svc_shutdown_net() have to
be skipped).
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFS: callback service creation function introduced
This function creates service if it's not exist, or increase usage counter of
the existent, and returns pointer to it.
Usage counter will be droppepd by svc_destroy() later in nfs_callback_up().
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
The OPEN operation has no way to differentiate an open for read and an
open for execution - both look like read to the server. This allowed
users to read files that didn't have READ access but did have EXEC access,
which is obviously wrong.
This patch adds an ACCESS call to the OPEN compound to handle the
difference between OPENs for reading and execution. Since we're going
through the trouble of calling ACCESS, we check all possible access bits
and cache the results hopefully avoiding an ACCESS call in the future.
I put the client into an open recovery loop by:
Client: Open file
read half
Server: Expire client (echo 0 > /sys/kernel/debug/nfsd/forget_clients)
Client: Drop vm cache (echo 3 > /proc/sys/vm/drop_caches)
finish reading file
This causes a loop because the client never updates the nfs4_state after
discovering that the delegation is invalid. This means it will keep
trying to read using the bad delegation rather than attempting to re-open
the file.
NFSv4.1: Get rid of the NFS_LAYOUT_DESTROYED state
We already have a mechanism for blocking LAYOUTGET by means of the
plh_block_lgets counter. The only "service" that NFS_LAYOUT_DESTROYED
provides at this point is to block layoutget once the layout segment
list is empty, which basically means that you have to wait until
the pnfs_layout_hdr is destroyed before you can do pNFS on that file
again.
This patch enables the reuse of the pnfs_layout_hdr if the layout
segment list is empty.
NFSv4.1: Remove redundant reference to the pnfs_layout_hdr
Each layout segment already holds a reference to the pnfs_layout_hdr,
so there is no need to hold an extra reference that is released once
the last layout segment is freed.
Ensure that pnfs_find_alloc_layout() always returns a reference
to the pnfs_layout_hdr, which will be matched by the final call to
pnfs_put_layout_hdr() in pnfs_update_layout().
NFSv4.1: Get rid of pNFS layout state "NFS_LAYOUT_INVALID"
In all cases where we set NFS_LAYOUT_INVALID, we also set NFS_LAYOUT_DESTROYED.
Furthermore, in all cases where we test for NFS_LAYOUT_INVALID, we should
also be testing for NFS_LAYOUT_DESTROYED, since the latter means that
we hold no valid layout segments.
Ergo the two are redundant.
NFSv4.1: pnfs_layout_io_set_failed must clear invalid lsegs
If pnfs_layout_io_test_failed() authorises a retry of the failed layoutgets,
we should clear the existing layout segments so that we start afresh. Do
this in pnfs_layout_io_set_failed().
NFSv4.1: pNFS data servers may be temporarily offline
In cases where the pNFS data server is just temporarily out of service,
we want to mark it as such, and then try again later. Typically that will
be in cases of network connection errors etc.
This patch allows us to mark the devices as being "unavailable" for such
transient errors, and will make them available for retries after a
2 minute timeout period.
If we had to fall back to read/write through MDS, then assume that we should
retry pNFS after a suitable timeout period.
The following patch sets a timeout of 2 minutes.
NFSv4.1: Replace dprintk() in pnfs_update_layout with something less buggy
Dereferencing nfsi->layout in order to read plh_flags without holding
a spin lock is bug prone. Furthermore, the dprintk() tells you nothing
about whether or not the call succeeded.
Replace it with something that tells you about whether or not a valid
layout segment was returned for the inode in question.
Ensure that we do return errors from nfs4_proc_layoutget() and that we
don't mark the layout as having failed if the error was due to a
signal or resource problem on the client side.
SUNRPC: Get rid of the redundant xprt->shutdown bit field
It is only set after everyone has dereferenced the transport,
and serves no useful purpose: setting it is racy, so all the
socket code, etc still needs to be able to cope with the cases
where they miss reading it.
NFS: Fix fdatasync/fsync() when confronted with a server reboot
If the server reboots before it can commit the unstable writes to disk,
then nfs_commit_release_pages() will detect this when it compares the
verifier returned by COMMIT to the one returned by WRITE. When this
happens, the client needs to resend those writes in order to guarantee
that they make it to stable storage.
This patch adds a signalling mechanism to notify fsync() that it
needs to retry all writes before it can exit.
Trond Myklebust [Mon, 13 Aug 2012 22:54:45 +0000 (18:54 -0400)]
NFS: Clean up helper function nfs4_select_rw_stateid()
We want to be able to pass on the information that the page was not
dirtied under a lock. Instead of adding a flag parameter, do this
by passing a pointer to a 'struct nfs_lock_owner' that may be NULL.
Also reuse this structure in struct nfs_lock_context to carry the
fl_owner_t and pid_t.
NFSv4: Remove BUG_ON() and ACCESS_ONCE() calls in the idmapper
The use of ACCESS_ONCE() is wrong, since the various routines that set/clear
idmap->idmap_key_cons should be strictly ordered w.r.t. each other, and
the idmap->idmap_mutex ensures that only one thread at a time may be in
an upcall situation.
Also replace the BUG_ON()s with WARN_ON_ONCE() where appropriate.
NFS4: avoid underflow when converting error to pointer.
In nfs4_create_sec_client, 'flavor' can hold a negative error
code (returned from nfs4_negotiate_security), even though it
is an 'enum' and hence unsigned.
The code is careful to cast it to an (int) before testing if it
is negative, however it doesn't cast to an (int) before calling
ERR_PTR.
On a machine where "void*" is larger than "int", this results in
the unsigned equivalent of -1 (e.g. 0xffffffff) being converted
to a pointer. Subsequent code determines that this is not
negative, and so dereferences it with predictable results.
So: cast 'flavor' to a (signed) int before passing to ERR_PTR.
In case of error, the function rpcauth_create() returns ERR_PTR()
and never returns NULL pointer. The NULL test in the return value
check should be replaced with IS_ERR().
dpatch engine is used to auto generated this patch.
(https://github.com/weiyj/dpatch)
f39c1bfb5a03e2d255451bff05be0d7255298fa4 (SUNRPC: Fix a UDP transport
regression) introduced the "alloc_slot" function for xprt operations,
but never created one for the backchannel operations. This patch fixes
a null pointer dereference when mounting NFS over v4.1.
Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:
"A small collection of driver fixes/updates and a core fix for 3.6. It
contains:
- Bug fixes for mtip32xx, and support for new hardware (just addition
of IDs). They have been queued up for 3.7 for a few weeks as well.
- rate-limit a failing command error message in block core.
- A fix for an old cciss bug from Stephen.
- Prevent overflow of partition count from Alan."
* 'for-linus' of git://git.kernel.dk/linux-block:
cciss: fix handling of protocol error
blk: add an upper sanity check on partition adding
mtip32xx: fix user_buffer check in exec_drive_command
mtip32xx: Remove dead code
mtip32xx: Change printk to pr_xxxx
mtip32xx: Proper reporting of write protect status on big-endian
mtip32xx: Increase timeout for standby command
mtip32xx: Handle NCQ commands during the security locked state
mtip32xx: Add support for new devices
block: rate-limit the error message from failing commands
Merge tag 'sh-for-linus' of git://github.com/pmundt/linux-sh
Pull SuperH fixes from Paul Mundt.
* tag 'sh-for-linus' of git://github.com/pmundt/linux-sh:
sh: Fix up TIF_NOTIFY_RESUME sans TIF_SIGPENDING handling.
sh: pfc: Release spinlock in sh_pfc_gpio_request_enable() error path
sh: intc: Fix up multi-evt irq association.
Merge tag 'md-3.6-fixes' of git://neil.brown.name/md
Pull md fixes from NeilBrown:
"3 fixes for md in 3.6.
One reverts a recent patch which turns out to not be such a good idea.
Other two fix minor bugs with the new (since 3.3) 'replacement' code
and have been tagged for -stable."
* tag 'md-3.6-fixes' of git://neil.brown.name/md:
md: make sure metadata is updated when spares are activated or removed.
md/raid5: fix calculate of 'degraded' when a replacement becomes active.
Revert "md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE."
Merge branch 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue / powernow-k8 fix from Tejun Heo:
"This is the fix for the bug where cpufreq/powernow-k8 was tripping
BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a
different CPU.
https://bugzilla.kernel.org/show_bug.cgi?id=47301
As discussed, the fix is now two parts - one to reimplement
work_on_cpu() so that it doesn't create a new kthread each time and
the actual fix which makes powernow-k8 use work_on_cpu() instead of
performing manual migration.
While pretty late in the merge cycle, both changes are on the safer
side. Jiri and I verified two existing users of work_on_cpu() and
Duncan confirmed that the powernow-k8 fix survived about 18 hours of
testing."
* 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU
workqueue: reimplement work_on_cpu() using system_wq
cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU
powernowk8_target() runs off a per-cpu work item and if the
cpufreq_policy->cpu is different from the current one, it migrates the
kworker to the target CPU by manipulating current->cpus_allowed. The
function migrates the kworker back to the original CPU but this is
still broken. Workqueue concurrency management requires the kworkers
to stay on the same CPU and powernowk8_target() ends up triggerring
BUG_ON(rq != this_rq()) in try_to_wake_up_local() if it contends on
fidvid_mutex and sleeps.
It is unclear why this bug is being reported now. Duncan says it
appeared to be a regression of 3.6-rc1 and couldn't reproduce it on
3.5. Bisection seemed to point to 63d95a91 "workqueue: use @pool
instead of @gcwq or @cpu where applicable" which is an non-functional
change. Given that the reproduce case sometimes took upto days to
trigger, it's easy to be misled while bisecting. Maybe something made
contention on fidvid_mutex more likely? I don't know.
This patch fixes the bug by using work_on_cpu() instead if @pol->cpu
isn't the same as the current one. The code assumes that
cpufreq_policy->cpu is kept online by the caller, which Rafael tells
me is the case.
stable: ed48ece27c ("workqueue: reimplement work_on_cpu() using
system_wq") should be applied before this; otherwise, the
behavior could be horrible.
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Duncan <1i5t5.duncan@cox.net> Tested-by: Duncan <1i5t5.duncan@cox.net> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Andreas Herrmann <andreas.herrmann3@amd.com> Cc: stable@vger.kernel.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47301
workqueue: reimplement work_on_cpu() using system_wq
The existing work_on_cpu() implementation is hugely inefficient. It
creates a new kthread, execute that single function and then let the
kthread die on each invocation.
Now that system_wq can handle concurrent executions, there's no
advantage of doing this. Reimplement work_on_cpu() using system_wq
which makes it simpler and way more efficient.
stable: While this isn't a fix in itself, it's needed to fix a
workqueue related bug in cpufreq/powernow-k8. AFAICS, this
shouldn't break other existing users.
Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Jiri Kosina <jkosina@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Len Brown <lenb@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@vger.kernel.org
md: make sure metadata is updated when spares are activated or removed.
It isn't always necessary to update the metadata when spares are
removed as the presence-or-not of a spare isn't really important to
the integrity of an array.
Also activating a spare doesn't always require updating the metadata
as the update on 'recovery-completed' is usually sufficient.
However the introduction of 'replacement' devices have made these
transitions sometimes more important. For example the 'Replacement'
flag isn't cleared until the original device is removed, so we need
to ensure a metadata update after that 'spare' is removed.
So set MD_CHANGE_DEVS whenever a spare is activated or removed, to
complement the current situation where it is set when a spare is added
or a device is failed (or a number of other less common situations).
This is suitable for -stable as out-of-data metadata could lead
to data corruption.
This is only relevant for 3.3 and later 9when 'replacement' as
introduced.
md/raid5: fix calculate of 'degraded' when a replacement becomes active.
When a replacement device becomes active, we mark the device that it
replaces as 'faulty' so that it can subsequently get removed.
However 'calc_degraded' only pays attention to the primary device, not
the replacement, so the array appears to become degraded, which is
wrong.
So teach 'calc_degraded' to consider any replacement if a primary
device is faulty.
This is suitable for -stable as an incorrect 'degraded' value can
confuse md and could lead to data corruption.
This is only relevant for 3.3 and later.
Cc: stable@vger.kernel.org Reported-by: Robin Hill <robin@robinhill.me.uk> Reported-by: John Drescher <drescherjm@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
While this patch seemed like a good idea and did help some workloads,
it hurts other workloads.
Large sequential O_DIRECT writes were faster,
Small random O_DIRECT writes were slower.
Other changes (batching RAID5 writes) have improved the sequential
writes using a different mechanism, so the net result of this patch
is definitely negative. So revert it.
Reported-by: Shaohua Li <shli@kernel.org> Tested-by: Jianpeng Ma <majianpeng@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
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