commit 06ba5d2e94 upstream.
The advertisement of the persistent grants feature (writing
'feature-persistent' to xenbus) should mean not the decision for using
the feature but only the availability of the feature. However, commit
aac8a70db2 ("xen-blkback: add a parameter for disabling of persistent
grants") made a field of blkback, which was a place for saving only the
negotiation result, to be used for yet another purpose: caching of the
'feature_persistent' parameter value. As a result, the advertisement,
which should follow only the parameter value, becomes inconsistent.
This commit fixes the misuse of the semantic by making blkback saves the
parameter value in a separate place and advertises the support based on
only the saved value.
Fixes: aac8a70db2 ("xen-blkback: add a parameter for disabling of persistent grants")
Cc: <stable@vger.kernel.org> # 5.10.x
Suggested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220831165824.94815-2-sj@kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e94c6101e1 upstream.
In some use cases[1], the backend is created while the frontend doesn't
support the persistent grants feature, but later the frontend can be
changed to support the feature and reconnect. In the past, 'blkback'
enabled the persistent grants feature since it unconditionally checked
if frontend supports the persistent grants feature for every connect
('connect_ring()') and decided whether it should use persistent grans or
not.
However, commit aac8a70db2 ("xen-blkback: add a parameter for
disabling of persistent grants") has mistakenly changed the behavior.
It made the frontend feature support check to not be repeated once it
shown the 'feature_persistent' as 'false', or the frontend doesn't
support persistent grants.
This commit changes the behavior of the parameter to make effect for
every connect, so that the previous workflow can work again as expected.
[1] https://lore.kernel.org/xen-devel/CAJwUmVB6H3iTs-C+U=v-pwJB7-_ZRHPxHzKRJZ22xEPW7z8a=g@mail.gmail.com/
Reported-by: Andrii Chepurnyi <andrii.chepurnyi82@gmail.com>
Fixes: aac8a70db2 ("xen-blkback: add a parameter for disabling of persistent grants")
Cc: <stable@vger.kernel.org> # 5.10.x
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Maximilian Heyne <mheyne@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220715225108.193398-3-sj@kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit fc9be616bb upstream.
Persistent grants feature can be used only when both backend and the
frontend supports the feature. The feature was always supported by
'blkback', but commit aac8a70db2 ("xen-blkback: add a parameter for
disabling of persistent grants") has introduced a parameter for
disabling it runtime.
To avoid the parameter be updated while being used by 'blkback', the
commit caches the parameter into 'vbd->feature_gnt_persistent' in
'xen_vbd_create()', and then check if the guest also supports the
feature and finally updates the field in 'connect_ring()'.
However, 'connect_ring()' could be called before 'xen_vbd_create()', so
later execution of 'xen_vbd_create()' can wrongly overwrite 'true' to
'vbd->feature_gnt_persistent'. As a result, 'blkback' could try to use
'persistent grants' feature even if the guest doesn't support the
feature.
This commit fixes the issue by moving the parameter value caching to
'xen_blkif_alloc()', which allocates the 'blkif'. Because the struct
embeds 'vbd' object, which will be used by 'connect_ring()' later, this
should be called before 'connect_ring()' and therefore this should be
the right and safe place to do the caching.
Fixes: aac8a70db2 ("xen-blkback: add a parameter for disabling of persistent grants")
Cc: <stable@vger.kernel.org> # 5.10.x
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Maximilian Heyne <mheyne@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220715225108.193398-2-sj@kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Delete/fixup few includes in anticipation of global -isystem compile
option removal.
Note: crypto/aegis128-neon-inner.c keeps <stddef.h> due to redefinition
of uintptr_t error (one definition comes from <stddef.h>, another from
<linux/types.h>).
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Prior to commit 4a8c31a1c6 ("xen/blkback: rework connect_ring() to avoid
inconsistent xenstore 'ring-page-order' set by malicious blkfront"), the
behaviour of xen-blkback when connecting to a frontend was:
- read 'ring-page-order'
- if not present then expect a single page ring specified by 'ring-ref'
- else expect a ring specified by 'ring-refX' where X is between 0 and
1 << ring-page-order
This was correct behaviour, but was broken by the afforementioned commit to
become:
- read 'ring-page-order'
- if not present then expect a single page ring (i.e. ring-page-order = 0)
- expect a ring specified by 'ring-refX' where X is between 0 and
1 << ring-page-order
- if that didn't work then see if there's a single page ring specified by
'ring-ref'
This incorrect behaviour works most of the time but fails when a frontend
that sets 'ring-page-order' is unloaded and replaced by one that does not
because, instead of reading 'ring-ref', xen-blkback will read the stale
'ring-ref0' left around by the previous frontend will try to map the wrong
grant reference.
This patch restores the original behaviour.
Fixes: 4a8c31a1c6 ("xen/blkback: rework connect_ring() to avoid inconsistent xenstore 'ring-page-order' set by malicious blkfront")
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: "Roger Pau Monné" <roger.pau@citrix.com>
Link: https://lore.kernel.org/r/20210202175659.18452-1-paul@xen.org
Signed-off-by: Juergen Gross <jgross@suse.com>
In order to support the possibility of per-device event channel
settings (e.g. lateeoi spurious event thresholds) add a xenbus device
pointer to struct irq_info() and modify the related event channel
binding interfaces to take the pointer to the xenbus device as a
parameter instead of the domain id of the other side.
While at it remove the stale prototype of bind_evtchn_to_irq_lateeoi().
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
When xen_blkif_disconnect() is called, the kernel thread behind the
block interface is stopped by calling kthread_stop(ring->xenblkd).
The ring->xenblkd thread pointer being non-NULL determines if the
thread has been already stopped.
Normally, the thread's function xen_blkif_schedule() sets the
ring->xenblkd to NULL, when the thread's main loop ends.
However, when the thread has not been started yet (i.e.
wake_up_process() has not been called on it), the xen_blkif_schedule()
function would not be called yet.
In such case the kthread_stop() call returns -EINTR and the
ring->xenblkd remains dangling.
When this happens, any consecutive call to xen_blkif_disconnect (for
example in frontend_changed() callback) leads to a kernel crash in
kthread_stop() (e.g. NULL pointer dereference in exit_creds()).
This is XSA-350.
Cc: <stable@vger.kernel.org> # 4.12
Fixes: a24fa22ce2 ("xen/blkback: don't use xen_blkif_get() in xen-blkback kthread")
Reported-by: Olivier Benjamin <oliben@amazon.com>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Some code does not directly make 'xenbus_watch' object and call
'register_xenbus_watch()' but use 'xenbus_watch_path()' instead. This
commit adds support of 'will_handle' callback in the
'xenbus_watch_path()' and it's wrapper, 'xenbus_watch_pathfmt()'.
This is part of XSA-349
Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Instead of having similar helpers in multiple backend drivers use
common helpers for caching pages allocated via gnttab_alloc_pages().
Make use of those helpers in blkback and scsiback.
Cc: <stable@vger.kernel.org> # 5.9
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovksy@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Persistent grants feature provides high scalability. On some small
systems, however, it could incur data copy overheads[1] and thus it is
required to be disabled. But, there is no option to disable it. For
the reason, this commit adds a module parameter for disabling of the
feature.
[1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability
Signed-off-by: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Link: https://lore.kernel.org/r/20200923061841.20531-2-sjpark@amazon.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
In order to reduce the chance for the system becoming unresponsive due
to event storms triggered by a misbehaving blkfront use the lateeoi
irq binding for blkback and unmask the event channel only after
processing all pending requests.
As the thread processing requests is used to do purging work in regular
intervals an EOI may be sent only after having received an event. If
there was no pending I/O request flag the EOI as spurious.
This is part of XSA-332.
Cc: stable@vger.kernel.org
Reported-by: Julien Grall <julien@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
The number of empty lines between functions in the xenbus.c is
inconsistent. This trivial style cleanup commit fixes the file to
consistently place only one empty line.
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Each `blkif` has a free pages pool for the grant mapping. The size of
the pool starts from zero and is increased on demand while processing
the I/O requests. If current I/O requests handling is finished or 100
milliseconds has passed since last I/O requests handling, it checks and
shrinks the pool to not exceed the size limit, `max_buffer_pages`.
Therefore, host administrators can cause memory pressure in blkback by
attaching a large number of block devices and inducing I/O. Such
problematic situations can be avoided by limiting the maximum number of
devices that can be attached, but finding the optimal limit is not so
easy. Improper set of the limit can results in memory pressure or a
resource underutilization. This commit avoids such problematic
situations by squeezing the pools (returns every free page in the pool
to the system) for a while (users can set this duration via a module
parameter) if memory pressure is detected.
Discussions
===========
The `blkback`'s original shrinking mechanism returns only pages in the
pool which are not currently be used by `blkback` to the system. In
other words, the pages that are not mapped with granted pages. Because
this commit is changing only the shrink limit but still uses the same
freeing mechanism it does not touch pages which are currently mapping
grants.
Once memory pressure is detected, this commit keeps the squeezing limit
for a user-specified time duration. The duration should be neither too
long nor too short. If it is too long, the squeezing incurring overhead
can reduce the I/O performance. If it is too short, `blkback` will not
free enough pages to reduce the memory pressure. This commit sets the
value as `10 milliseconds` by default because it is a short time in
terms of I/O while it is a long time in terms of memory operations.
Also, as the original shrinking mechanism works for at least every 100
milliseconds, this could be a somewhat reasonable choice. I also tested
other durations (refer to the below section for more details) and
confirmed that 10 milliseconds is the one that works best with the test.
That said, the proper duration depends on actual configurations and
workloads. That's why this commit allows users to set the duration as a
module parameter.
Memory Pressure Test
====================
To show how this commit fixes the memory pressure situation well, I
configured a test environment on a xen-running virtualization system.
On the `blkfront` running guest instances, I attach a large number of
network-backed volume devices and induce I/O to those. Meanwhile, I
measure the number of pages that swapped in (pswpin) and out (pswpout)
on the `blkback` running guest. The test ran twice, once for the
`blkback` before this commit and once for that after this commit. As
shown below, this commit has dramatically reduced the memory pressure:
pswpin pswpout
before 76,672 185,799
after 867 3,967
Optimal Aggressive Shrinking Duration
-------------------------------------
To find a best squeezing duration, I repeated the test with three
different durations (1ms, 10ms, and 100ms). The results are as below:
duration pswpin pswpout
1 707 5,095
10 867 3,967
100 362 3,348
As expected, the memory pressure decreases as the duration increases,
but the reduction become slow from the `10ms`. Based on this results, I
chose the default duration as 10ms.
Performance Overhead Test
=========================
This commit could incur I/O performance degradation under severe memory
pressure because the squeezing will require more page allocations per
I/O. To show the overhead, I artificially made a worst-case squeezing
situation and measured the I/O performance of a `blkfront` running
guest.
For the artificial squeezing, I set the `blkback.max_buffer_pages` using
the `/sys/module/xen_blkback/parameters/max_buffer_pages` file. In this
test, I set the value to `1024` and `0`. The `1024` is the default
value. Setting the value as `0` is same to a situation doing the
squeezing always (worst-case).
If the underlying block device is slow enough, the squeezing overhead
could be hidden. For the reason, I use a fast block device, namely the
rbd[1]:
# xl block-attach guest phy:/dev/ram0 xvdb w
For the I/O performance measurement, I run a simple `dd` command 5 times
directly to the device as below and collect the 'MB/s' results.
$ for i in {1..5}; do dd if=/dev/zero of=/dev/xvdb \
bs=4k count=$((256*512)); sync; done
The results are as below. 'max_pgs' represents the value of the
`blkback.max_buffer_pages` parameter.
max_pgs Min Max Median Avg Stddev
0 417 423 420 419.4 2.5099801
1024 414 425 416 417.8 4.4384682
No difference proven at 95.0% confidence
In short, even worst case squeezing on ramdisk based fast block device
makes no visible performance degradation. Please note that this is just
a very simple and minimal test. On systems using super-fast block
devices and a special I/O workload, the results might be different. If
you have any doubt, test on your machine with your workload to find the
optimal squeezing duration for you.
[1] https://www.kernel.org/doc/html/latest/admin-guide/blockdev/ramdisk.html
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
By simply re-attaching to shared rings during connect_ring() rather than
assuming they are freshly allocated (i.e assuming the counters are zero)
it is possible for vbd instances to be unbound and re-bound from and to
(respectively) a running guest.
This has been tested by running:
while true;
do fio --name=randwrite --ioengine=libaio --iodepth=16 \
--rw=randwrite --bs=4k --direct=1 --size=1G --verify=crc32;
done
in a PV guest whilst running:
while true;
do echo vbd-$DOMID-$VBD >unbind;
echo unbound;
sleep 5;
echo vbd-$DOMID-$VBD >bind;
echo bound;
sleep 3;
done
in dom0 from /sys/bus/xen-backend/drivers/vbd to continuously unbind and
re-bind its system disk image.
This is a highly useful feature for a backend module as it allows it to be
unloaded and re-loaded (i.e. updated) without requiring domUs to be halted.
This was also tested by running:
while true;
do echo vbd-$DOMID-$VBD >unbind;
echo unbound;
sleep 5;
rmmod xen-blkback;
echo unloaded;
sleep 1;
modprobe xen-blkback;
echo bound;
cd $(pwd);
sleep 3;
done
in dom0 whilst running the same loop as above in the (single) PV guest.
Some (less stressful) testing has also been done using a Windows HVM guest
with the latest 9.0 PV drivers installed.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Objects allocated by xen_blkif_alloc come from the 'blkif_cache' kmem
cache. This cache is destoyed when xen-blkif is unloaded so it is
necessary to wait for the deferred free routine used for such objects to
complete. This necessity was missed in commit 14855954f6 "xen-blkback:
allow module to be cleanly unloaded". This patch fixes the problem by
taking/releasing extra module references in xen_blkif_alloc/free()
respectively.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
In read_per_ring_refs(), after 'req' and related memory regions are
allocated, xen_blkif_map() is invoked to map the shared frame, irq, and
etc. However, if this mapping process fails, no cleanup is performed,
leading to memory leaks. To fix this issue, invoke the cleanup before
returning the error.
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Based on 3 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [kishon] [vijay] [abraham]
[i] [kishon]@[ti] [com] this program is distributed in the hope that
it will be useful but without any warranty without even the implied
warranty of merchantability or fitness for a particular purpose see
the gnu general public license for more details
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [graeme] [gregory]
[gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i]
[kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema]
[hk] [hemahk]@[ti] [com] this program is distributed in the hope
that it will be useful but without any warranty without even the
implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1105 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The xenstore 'ring-page-order' is used globally for each blkback queue and
therefore should be read from xenstore only once. However, it is obtained
in read_per_ring_refs() which might be called multiple times during the
initialization of each blkback queue.
If the blkfront is malicious and the 'ring-page-order' is set in different
value by blkfront every time before blkback reads it, this may end up at
the "WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));" in
xen_blkif_disconnect() when frontend is destroyed.
This patch reworks connect_ring() to read xenstore 'ring-page-order' only
once.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
As 'be->blkif' is used for many times in connect_ring(), the stack variable
'blkif' is added to substitute 'be-blkif'.
Suggested-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Convert the S_<FOO> symbolic permissions to their octal equivalents as
using octal and not symbolic permissions is preferred by many as more
readable.
see: https://lkml.org/lkml/2016/8/2/1945
Done with automated conversion via:
$ ./scripts/checkpatch.pl -f --types=SYMBOLIC_PERMS --fix-inplace <files...>
Miscellanea:
o Wrapped modified multi-line calls to a single line where appropriate
o Realign modified multi-line calls to open parenthesis
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block layer updates from Jens Axboe:
"This is the first pull request for 4.14, containing most of the code
changes. It's a quiet series this round, which I think we needed after
the churn of the last few series. This contains:
- Fix for a registration race in loop, from Anton Volkov.
- Overflow complaint fix from Arnd for DAC960.
- Series of drbd changes from the usual suspects.
- Conversion of the stec/skd driver to blk-mq. From Bart.
- A few BFQ improvements/fixes from Paolo.
- CFQ improvement from Ritesh, allowing idling for group idle.
- A few fixes found by Dan's smatch, courtesy of Dan.
- A warning fixup for a race between changing the IO scheduler and
device remova. From David Jeffery.
- A few nbd fixes from Josef.
- Support for cgroup info in blktrace, from Shaohua.
- Also from Shaohua, new features in the null_blk driver to allow it
to actually hold data, among other things.
- Various corner cases and error handling fixes from Weiping Zhang.
- Improvements to the IO stats tracking for blk-mq from me. Can
drastically improve performance for fast devices and/or big
machines.
- Series from Christoph removing bi_bdev as being needed for IO
submission, in preparation for nvme multipathing code.
- Series from Bart, including various cleanups and fixes for switch
fall through case complaints"
* 'for-4.14/block' of git://git.kernel.dk/linux-block: (162 commits)
kernfs: checking for IS_ERR() instead of NULL
drbd: remove BIOSET_NEED_RESCUER flag from drbd_{md_,}io_bio_set
drbd: Fix allyesconfig build, fix recent commit
drbd: switch from kmalloc() to kmalloc_array()
drbd: abort drbd_start_resync if there is no connection
drbd: move global variables to drbd namespace and make some static
drbd: rename "usermode_helper" to "drbd_usermode_helper"
drbd: fix race between handshake and admin disconnect/down
drbd: fix potential deadlock when trying to detach during handshake
drbd: A single dot should be put into a sequence.
drbd: fix rmmod cleanup, remove _all_ debugfs entries
drbd: Use setup_timer() instead of init_timer() to simplify the code.
drbd: fix potential get_ldev/put_ldev refcount imbalance during attach
drbd: new disk-option disable-write-same
drbd: Fix resource role for newly created resources in events2
drbd: mark symbols static where possible
drbd: Send P_NEG_ACK upon write error in protocol != C
drbd: add explicit plugging when submitting batches
drbd: change list_for_each_safe to while(list_first_entry_or_null)
drbd: introduce drbd_recv_header_maybe_unplug
...
In xen_blkif_disconnect, before checking inflight I/O, following code
stops the blkback thread,
if (ring->xenblkd) {
kthread_stop(ring->xenblkd);
wake_up(&ring->shutdown_wq);
}
If there is inflight I/O in any non-last queue, blkback returns -EBUSY
directly, and above code would not be called to stop thread of remaining
queue and processs them. When removing vbd device with lots of disk I/O
load, some queues with inflight I/O still have blkback thread running even
though the corresponding vbd device or guest is gone.
And this could cause some problems, for example, if the backend device type
is file, some loop devices and blkback thread always lingers there forever
after guest is destroyed, and this causes failure of umounting repositories
unless rebooting the dom0.
This patch allows thread of every queue has the chance to get stopped.
Otherwise, only thread of queue previous to(including) first busy one get
stopped, blkthread of remaining queue will still run. So stop all threads
properly and return -EBUSY if any queue has inflight I/O.
Signed-off-by: Annie Li <annie.li@oracle.com>
Reviewed-by: Herbert van den Bergh <herbert.van.den.bergh@oracle.com>
Reviewed-by: Bhavesh Davda <bhavesh.davda@oracle.com>
Reviewed-by: Adnan Misherfi <adnan.misherfi@oracle.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
There is no need to use xen_blkif_get()/xen_blkif_put() in the kthread
of xen-blkback. Thread stopping is synchronous and using the blkif
reference counting in the kthread will avoid to ever let the reference
count drop to zero at the end of an I/O running concurrent to
disconnecting and multiple rings.
Setting ring->xenblkd to NULL after stopping the kthread isn't needed
as the kthread does this already.
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Steven Haigh <netwiz@crc.id.au>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The be structure must not be freed when freeing the blkif structure
isn't done. Otherwise a use-after-free of be when unmapping the ring
used for communicating with the frontend will occur in case of a
late call of xenblk_disconnect() (e.g. due to an I/O still active
when trying to disconnect).
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Steven Haigh <netwiz@crc.id.au>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Today disconnecting xen-blkback is broken in case there are still
I/Os in flight: xen_blkif_disconnect() will bail out early without
releasing all resources in the hope it will be called again when
the last request has terminated. This, however, won't happen as
xen_blkif_free() won't be called on termination of the last running
request: xen_blkif_put() won't decrement the blkif refcnt to 0 as
xen_blkif_disconnect() didn't finish before thus some xen_blkif_put()
calls in xen_blkif_disconnect() didn't happen.
To solve this deadlock xen_blkif_disconnect() and
xen_blkif_alloc_rings() shouldn't use xen_blkif_put() and
xen_blkif_get() but use some other way to do their accounting of
resources.
This at once fixes another error in xen_blkif_disconnect(): when it
returned early with -EBUSY for another ring than 0 it would call
xen_blkif_put() again for already handled rings on a subsequent call.
This will lead to inconsistencies in the refcnt handling.
Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Steven Haigh <netwiz@crc.id.au>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Today a Xenstore watch event is delivered via a callback function
declared as:
void (*callback)(struct xenbus_watch *,
const char **vec, unsigned int len);
As all watch events only ever come with two parameters (path and token)
changing the prototype to:
void (*callback)(struct xenbus_watch *,
const char *path, const char *token);
is the natural thing to do.
Apply this change and adapt all users.
Cc: konrad.wilk@oracle.com
Cc: roger.pau@citrix.com
Cc: wei.liu2@citrix.com
Cc: paul.durrant@citrix.com
Cc: netdev@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of one read from int to unsigned,
but this case has been wrong before: negative values are not allowed
for the modified case.
Cc: konrad.wilk@oracle.com
Cc: roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
- ACPI support for guests on ARM platforms.
- Generic steal time support for arm and x86.
- Support cases where kernel cpu is not Xen VCPU number (e.g., if
in-guest kexec is used).
- Use the system workqueue instead of a custom workqueue in various
places.
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Merge tag 'for-linus-4.8-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen updates from David Vrabel:
"Features and fixes for 4.8-rc0:
- ACPI support for guests on ARM platforms.
- Generic steal time support for arm and x86.
- Support cases where kernel cpu is not Xen VCPU number (e.g., if
in-guest kexec is used).
- Use the system workqueue instead of a custom workqueue in various
places"
* tag 'for-linus-4.8-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: (47 commits)
xen: add static initialization of steal_clock op to xen_time_ops
xen/pvhvm: run xen_vcpu_setup() for the boot CPU
xen/evtchn: use xen_vcpu_id mapping
xen/events: fifo: use xen_vcpu_id mapping
xen/events: use xen_vcpu_id mapping in events_base
x86/xen: use xen_vcpu_id mapping when pointing vcpu_info to shared_info
x86/xen: use xen_vcpu_id mapping for HYPERVISOR_vcpu_op
xen: introduce xen_vcpu_id mapping
x86/acpi: store ACPI ids from MADT for future usage
x86/xen: update cpuid.h from Xen-4.7
xen/evtchn: add IOCTL_EVTCHN_RESTRICT
xen-blkback: really don't leak mode property
xen-blkback: constify instance of "struct attribute_group"
xen-blkfront: prefer xenbus_scanf() over xenbus_gather()
xen-blkback: prefer xenbus_scanf() over xenbus_gather()
xen: support runqueue steal time on xen
arm/xen: add support for vm_assist hypercall
xen: update xen headers
xen-pciback: drop superfluous variables
xen-pciback: short-circuit read path used for merging write values
...
Commit 9d092603cc ("xen-blkback: do not leak mode property") left one
path unfixed; correct this.
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The functions these get passed to have been taking pointers to const
since at least 2.6.16.
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
... for single items being collected: It is more typesafe (as the
compiler can check format string and to-be-written-to variable match)
and requires one less parameter to be passed.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Instead of overloading the discard support with the REQ_SECURE flag.
Use the opportunity to rename the queue flag as well, and remove the
dead checks for this flag in the RAID 1 and RAID 10 drivers that don't
claim support for secure erase.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Now that we converted everything to the newer block write cache
interface, kill off the queue flush_flags and queueable flush
entries.
Signed-off-by: Jens Axboe <axboe@fb.com>
The processes names are truncated to 17, while we had the length
of the process as name 20 - which meant that while we filled
it out with various details - the last 3 characters (which had
the queue number) never surfaced to the user-space.
To simplify this and be able to fit the device name, domain id,
and the queue number we remove the 'blkback' from the name.
Prior to this patch the device name is "blkback.<domid>.<name>"
for example: blkback.8.xvda, blkback.11.hda.
With the multiqueue block backend we add "-%d" for the queue.
But sadly this is already way past the limit so it gets stripped.
Possible solution had been identified by Ian:
http://lists.xenproject.org/archives/html/xen-devel/2015-05/msg03516.html
"
If you are pressed for space then the "xvd" is probably a bit redundant
in a string which starts blkbk.
The guest may not even call the device xvdN (iirc BSD has another
prefix) any how, so having blkback say so seems of limited use anyway.
Since this seems to not include a partition number how does this work in
the split partition scheme? (i.e. one where the guest is given xvda1 and
xvda2 rather than xvda with a partition table)
[It will be 'blkback.8.xvda1', and 'blkback.11.xvda2']
Perhaps something derived from one of the schemes in
http://xenbits.xen.org/docs/unstable/misc/vbd-interface.txt might be a
better fit?
After a bit of discussion (see
http://lists.xenproject.org/archives/html/xen-devel/2015-12/msg01588.html)
we settled on dropping the "blback" part.
This will make it possible to have the <domid>.<name>-<queue>:
[1.xvda-0]
[1.xvda-1]
And we enough space to make it go up to:
[32100.xvdfg9-5]
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
There's no reason to defer this until the connect phase, and in fact
there are frontend implementations expecting this to be available
earlier. Move it into the probe function.
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This patch fixs two memleaks:
backtrace:
[<ffffffff817ba5e8>] kmemleak_alloc+0x28/0x50
[<ffffffff81205e3b>] kmem_cache_alloc+0xbb/0x1d0
[<ffffffff81534028>] xen_blkbk_probe+0x58/0x230
[<ffffffff8146adb6>] xenbus_dev_probe+0x76/0x130
[<ffffffff81511716>] driver_probe_device+0x166/0x2c0
[<ffffffff815119bc>] __device_attach_driver+0xac/0xb0
[<ffffffff8150fa57>] bus_for_each_drv+0x67/0x90
[<ffffffff81511ab7>] __device_attach+0xc7/0x120
[<ffffffff81511b23>] device_initial_probe+0x13/0x20
[<ffffffff8151059a>] bus_probe_device+0x9a/0xb0
[<ffffffff8150f0a1>] device_add+0x3b1/0x5c0
[<ffffffff8150f47e>] device_register+0x1e/0x30
[<ffffffff8146a9e8>] xenbus_probe_node+0x158/0x170
[<ffffffff8146abaf>] xenbus_dev_changed+0x1af/0x1c0
[<ffffffff8146b1bb>] backend_changed+0x1b/0x20
[<ffffffff81468ca6>] xenwatch_thread+0xb6/0x160
unreferenced object 0xffff880007ba8ef8 (size 224):
backtrace:
[<ffffffff817ba5e8>] kmemleak_alloc+0x28/0x50
[<ffffffff81205c73>] __kmalloc+0xd3/0x1e0
[<ffffffff81534d87>] frontend_changed+0x2c7/0x580
[<ffffffff8146af12>] xenbus_otherend_changed+0xa2/0xb0
[<ffffffff8146b2c0>] frontend_changed+0x10/0x20
[<ffffffff81468ca6>] xenwatch_thread+0xb6/0x160
[<ffffffff810d3e97>] kthread+0xd7/0xf0
[<ffffffff817c4a9f>] ret_from_fork+0x3f/0x70
[<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff8800048dcd38 (size 224):
The first leak is caused by not put() the be->blkif reference
which we had gotten in xen_blkif_alloc(), while the second is
us not freeing blkif->rings in the right place.
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Reported-and-Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Make st_* statistics per ring and the VBD sysfs would iterate over all the
rings.
Note: xenvbd_sysfs_delif() is called in xen_blkbk_remove() before all rings
are torn down, so it's safe.
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v2: Aligned the variables on the same column.
With the multi-queue support we could fail at setting up
some of the rings and fail the connection. That meant that
all resources tied to rings[0..n-1] (where n is the ring
that failed to be setup). Eventually the frontend will switch
to the states and we will call xen_blkif_disconnect.
However we do not want to be at the mercy of the frontend
deciding when to change states. This allows us to do the
cleanup right away and freeing resources.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Make pool of persistent grants and free pages per-queue/ring instead of
per-device to get better scalability.
Test was done based on null_blk driver:
dom0: v4.2-rc8 16vcpus 10GB "modprobe null_blk"
domu: v4.2-rc8 16vcpus 10GB
[test]
rw=read
direct=1
ioengine=libaio
bs=4k
time_based
runtime=30
filename=/dev/xvdb
numjobs=16
iodepth=64
iodepth_batch=64
iodepth_batch_complete=64
group_reporting
Results:
iops1: After patch "xen/blkfront: make persistent grants per-queue".
iops2: After this patch.
Queues: 1 4 8 16
Iops orig(k): 810 1064 780 700
Iops1(k): 810 1230(~20%) 1024(~20%) 850(~20%)
Iops2(k): 810 1410(~35%) 1354(~75%) 1440(~100%)
With 4 queues after this commit we can get ~75% increase in IOPS, and
performance won't drop if increasing queue numbers.
Please find the respective chart in this link:
https://www.dropbox.com/s/agrcy2pbzbsvmwv/iops.png?dl=0
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Backend advertises "multi-queue-max-queues" to front, also get the negotiated
number from "multi-queue-num-queues" written by blkfront.
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Preparatory patch for multiple hardware queues (rings). The number of
rings is unconditionally set to 1, larger number will be enabled in
"xen/blkback: get the number of hardware queues/rings from blkfront".
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v2: Align variables in the structures.
Split per ring information to an new structure "xen_blkif_ring", so that one vbd
device can be associated with one or more rings/hardware queues.
Introduce 'pers_gnts_lock' to protect the pool of persistent grants since we
may have multi backend threads.
This patch is a preparation for supporting multi hardware queues/rings.
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v2: Align the variables in the structure.
Linux may use a different page size than the size of grant. So make
clear that the order is actually in number of grant.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
The PV block protocol is using 4KB page granularity. The goal of this
patch is to allow a Linux using 64KB page granularity behaving as a
block backend on a non-modified Xen.
It's only necessary to adapt the ring size and the number of request per
indirect frames. The rest of the code is relying on the grant table
code.
Note that the grant table code is allocating a Linux page per grant
which will result to waste 6OKB for every grant when Linux is using 64KB
page granularity. This could be improved by sharing the page between
multiple grants.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Acked-by: "Roger Pau Monné" <roger.pau@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
SeongJae Park
Maximilian Heyne
Alexey Dobriyan
Paul Durrant
Juergen Gross
Pawel Wieczorkiewicz
SeongJae Park
Gustavo A. R. Silva
Wenwen Wang
Thomas Gleixner
Dongli Zhang
Kees Cook
Joe Perches
Linus Torvalds
Annie Li
Bart Van Assche
Gustavo A. R. Silva
Jan Beulich
Christoph Hellwig
Jens Axboe
Konrad Rzeszutek Wilk
Bob Liu
Julien Grall
