The "mon_name" argument of the NSMPROC_MON and NSMPROC_UNMON upcalls
is a string that contains the hostname or IP address of the remote peer
to be notified when this host has rebooted. The sm-notify command uses
this identifier to contact the peer when we reboot, so it must be
either a well-qualified DNS hostname or a presentation format IP
address string.
When the "nsm_use_hostnames" sysctl is set to zero, the kernel's NSM
provides a presentation format IP address in the "mon_name" argument.
Otherwise, the "caller_name" argument from NLM requests is used,
which is usually just the DNS hostname of the peer.
To support IPv6 addresses for the mon_name argument, we use the
nsm_handle's address eye-catcher, which already contains an appropriate
presentation format address string. Using the eye-catcher string
obviates the need to use a large buffer on the stack to form the
presentation address string for the upcall.
This patch also addresses a subtle bug.
An NSMPROC_MON request and the subsequent NSMPROC_UNMON request for the
same peer are required to use the same value for the "mon_name"
argument. Otherwise, rpc.statd's NSMPROC_UNMON processing cannot
locate the database entry for that peer and remove it.
If the setting of nsm_use_hostnames is changed between the time the
kernel sends an NSMPROC_MON request and the time it sends the
NSMPROC_UNMON request for the same peer, the "mon_name" argument for
these two requests may not be the same. This is because the value of
"mon_name" is currently chosen at the moment the call is made based on
the setting of nsm_use_hostnames
To ensure both requests pass identical contents in the "mon_name"
argument, we now select which string to use for the argument in the
nsm_monitor() function. A pointer to this string is saved in the
nsm_handle so it can be used for a subsequent NSMPROC_UNMON upcall.
NB: There are other potential problems, such as how nlm_host_rebooted()
might behave if nsm_use_hostnames were changed while hosts are still
being monitored. This patch does not attempt to address those
problems.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Clean up: I'm about to add another "char *" field to the nsm_handle
structure. The sm_name field uses an older style of declaring a
"char *" field. If I match that style for the new field, checkpatch.pl
will complain.
So, fix the sm_name field to use the new style.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Clean up: make the printk(KERN_DEBUG) in nsm_mon_unmon() a dprintk,
and add another dprintk to note if creating an RPC client for the
upcall failed.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Clean up: Use a C99 structure initializer instead of open-coding the
initialization of nsm_args.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Clean up: introduce a helper function to generate IPv4 addresses using
the same style as the IPv6 helper function we just added.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Scope ID support is needed since the kernel's NSM implementation is
about to use these displayed addresses as a mon_name in some cases.
When nsm_use_hostnames is zero, without scope ID support NSM will fail
to handle peers that contact us via a link-local address. Link-local
addresses do not work without an interface ID, which is stored in the
sockaddr's sin6_scope_id field.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
AF_UNSPEC support is no longer needed in nlm_display_address() now
that a presentation address is no longer generated for the h_srcaddr
field.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
The h_name field in struct nlm_host is a just copy of
h_nsmhandle->sm_name. Likewise, the contents of the h_addrbuf field
should be identical to the sm_addrbuf field.
The h_srcaddrbuf field is used only in one place for debugging. We can
live without this until we get %pI formatting for printk().
Currently these buffers are 48 bytes, but we need to support scope IDs
in IPv6 presentation addresses, which means making the buffers even
larger. Instead, let's find ways to eliminate them to save space.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Clean up: I'm about to add another "char *" field to the nlm_host
structure. The h_name field, for example, uses an older style of
declaring a "char *" field. If I match that style for the new field,
checkpatch.pl will complain.
So, fix pointer fields to use the new style.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
The default method for calculating the number of connections allowed
per RPC service arbitrarily limits single-threaded services to 80
connections. This is too low for services like lockd and artificially
limits the number of TCP clients that it can support.
Have lockd set a default sv_maxconn value to 1024 (which is the typical
default value for RLIMIT_NOFILE. Also add a module parameter to allow an
admin to set this to an arbitrary value.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Neil Brown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
svc_check_conn_limits() attempts to prevent denial of service attacks
by having the service close old connections once it reaches a
threshold. This threshold is based on the number of threads in the
service:
(serv->sv_nrthreads + 3) * 20
Once we reach this, we drop the oldest connections and a printk pops
to warn the admin that they should increase the number of threads.
Increasing the number of threads isn't an option however for services
like lockd. We don't want to eliminate this check entirely for such
services but we need some way to increase this limit.
This patch adds a sv_maxconn field to the svc_serv struct. When it's
set to 0, we use the current method to calculate the max number of
connections. RPC services can then set this on an as-needed basis.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Neil Brown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
cksum.data is not freed up in one error case. Compile tested.
Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Supply dm_add_exception as a callback to the read_metadata function.
Add a status function ready for a later patch and name the functions
consistently.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Move the existing snapshot exception store implementations out into
separate files. Later patches will place these behind a new
interface in preparation for alternative implementations.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Rename struct exception_store to dm_exception_store.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Pull structures that bridge the gap between snapshot and
exception store out of dm-snap.h and put them in a new
.h file - dm-exception-store.h. This file will define the
API for new exception stores.
Ultimately, dm-snap.h is unnecessary, since only dm-snap.c
should be using it.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
The same workqueue is used both for sending uevents and processing queued I/O.
Deadlock has been reported in RHEL5 when sending a uevent was blocked waiting
for the queued I/O to be processed. Use scheduled_work() for the asynchronous
uevents instead.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Implement simple read-only sysfs entry for device-mapper block device.
This patch adds a simple sysfs directory named "dm" under block device
properties and implements
- name attribute (string containing mapped device name)
- uuid attribute (string containing UUID, or empty string if not set)
The kobject is embedded in mapped_device struct, so no additional
memory allocation is needed for initializing sysfs entry.
During the processing of sysfs attribute we need to lock mapped device
which is done by a new function dm_get_from_kobj, which returns the md
associated with kobject and increases the usage count.
Each 'show attribute' function is responsible for its own locking.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Rework table reference counting.
The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.
This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
same process.
* stale reference from some other kernel code keeps the table
constructed, which keeps some devices open, even after successful
return from "dmsetup remove". This can confuse lvm and prevent closing
of underlying devices or reusing device minor numbers.
The patch changes reference counting so that the table destructor can be
called only at predetermined places.
The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders. A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.
Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.
When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor. We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.
This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.
Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Implement barrier support for single device DM devices
This patch implements barrier support in DM for the common case of dm linear
just remapping a single underlying device. In this case we can safely
pass the barrier through because there can be no reordering between
devices.
NB. Any DM device might cease to support barriers if it gets
reconfigured so code must continue to allow for a possible
-EOPNOTSUPP on every barrier bio submitted. - agk
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This patch adds the following target interfaces for request-based dm.
map_rq : for mapping a request
rq_end_io : for finishing a request
busy : for avoiding performance regression from bio-based dm.
Target can tell dm core not to map requests now, and
that may help requests in the block layer queue to be
bigger by I/O merging.
In bio-based dm, this behavior is done by device
drivers managing the block layer queue.
But in request-based dm, dm core has to do that
since dm core manages the block layer queue.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Chuck Lever
Jeff Layton
J. Bruce Fields
Krishna Kumar
Linus Torvalds
Jonathan Brassow
Alasdair G Kergon
Milan Broz
Mikulas Patocka
Andi Kleen
Kiyoshi Ueda