Fix regression for HVM case on older (<4.1.1) hypervisors caused by
commit 99bbb3a84a
Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Date: Thu Dec 2 17:55:10 2010 +0000
xen: PV on HVM: support PV spinlocks and IPIs
This change replaced the SMP operations with event based handlers without
taking into account that this only works when the hypervisor supports
callback vectors. This causes unexplainable hangs early on boot for
HVM guests with more than one CPU.
BugLink: http://bugs.launchpad.net/bugs/791850
CC: stable@kernel.org
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-and-Reported-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
In case we have a pending completion, for example due to a problem with
the input clock which got corrected after we timed out.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
We get called once per DAPM context but only need to run once. When DAPM
was serialized this was a series of noops but now it can run in parallel
we need to take proper care.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
There's no need for separate widgets for the enables (as the map already
shows).
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Make AIFCLK supply the record paths otherwise record will not work unless
there is a simultaneous playback.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Otherwise these would need to be painstakingly calculated looking at the source
code.
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Alpha needs to have available the system bus address for the Radeon's
local memory, so that it can be used in ttm_bo_vm_fault(), when building
the PTEs for accessing that VRAM. So, we make bus.addr hold the ioremap()
return, and then we can modify bus.base appropriately for use during page
fault processing.
Signed-off-by: Jay Estabrook <jay.estabrook@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
ep93xx_keypad.c uses interfaces from linux/module.h,
so it should include that file. This patch fixes build errors.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
tnetv107x-ts.c uses interfaces from linux/module.h,
so it should include that file. This patch fixes build errors.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This fixes a regression introduced by commit cdcb725c05 ("Btrfs: check
if there is enough space for balancing smarter"). We can't do 64-bit
divides on 32-bit architectures.
In cases where we need to divide/multiply by 2 we should just left/right
shift respectively, and in cases where theres N number of devices use
do_div. Also make the counters u64 to match up with rw_devices.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Acked-and-tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: flush any pending end_io requests before DIO reads w/dioread_nolock
ext4: fix nomblk_io_submit option so it correctly converts uninit blocks
ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.
ext4: call ext4_ioend_wait and ext4_flush_completed_IO in ext4_evict_inode
ext4: Fix ext4_should_writeback_data() for no-journal mode
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
ALSA: sound/aoa/fabrics/layout.c: remove unneeded kfree
ALSA: hda - Fix error check from snd_hda_get_conn_index() in patch_cirrus.c
ALSA: hda - Don't spew too many ELD errors
ALSA: usb-audio - Fix missing mixer dB information
ALSA: hda - Add "PCM" volume to vmaster slave list
ALSA: hda - Fix duplicated capture-volume creation for ALC268 models
ALSA: ac97: Add HP Compaq dc5100 SFF(PT003AW) to Headphone Jack Sense whitelist
ALSA: snd_usb_caiaq: track submitted output urbs
Fix new kernel-doc warning in pci.c:
Warning(drivers/pci/pci.c:3259): No description found for parameter 'mps'
Warning(drivers/pci/pci.c:3259): Excess function parameter 'rq' description in 'pcie_set_mps'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we can't push the pending register windows onto the user's stack,
we disallow signal delivery even if the signal would be delivered on a
valid seperate signal stack.
Add a register window save area in the signal frame, and store any
unsavable windows there.
On sigreturn, if any windows are still queued up in the signal frame,
try to push them back onto the stack and if that fails we kill the
process immediately.
This allows the debug/tst-longjmp_chk2 glibc test case to pass.
Signed-off-by: David S. Miller <davem@davemloft.net>
The original license statement was confusing since it was unclear if
the license was pure GPLv2 or GPLv2+ and did not match the license
of the driver max11801_ts was derived from. The license is GPLv2+.
Signed-off-by: Jiejing Zhang <jiejing.zhang@freescale.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This oops have been already fixed with commit
27141666b6
atm: [br2684] Fix oops due to skb->dev being NULL
It happens that if a packet arrives in a VC between the call to open it on
the hardware and the call to change the backend to br2684, br2684_regvcc
processes the packet and oopses dereferencing skb->dev because it is
NULL before the call to br2684_push().
but have been introduced again with commit
b6211ae7f2
atm: Use SKB queue and list helpers instead of doing it by-hand.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The label outnodev is only used when kzalloc has not yet taken place or has
failed, so there is no need for the call for kfree under this label.
A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)
// <smpl>
@@
identifier x;
expression E1!=0,E2,E3,E4;
statement S;
iterator I;
@@
(
if (...) { ... when != kfree(x)
when != x = E3
when != E3 = x
* return ...;
}
... when != x = E2
when != I(...,x,...) S
if (...) { ... when != x = E4
kfree(x); ... return ...; }
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
snd_hda_get_conn_index() returns a negative value while the current code
stores it in an unsigned int. It must be stored in a signed integer.
Reported-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Currently HD-audio driver shows the all error ELD byte as an error
in the kernel message. This is annoying when the video driver doesn't
set the correct ELD from the beginning. e.g. radeon sends a zero-byte
data, but we still check ELD with the fixed 128 byte as a workaround
for some broken devices, it spews 128-times errors.
For avoiding this, the driver aborts reading when the first byte is
invalid. In such a case, the whole data is certainly invalid.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/drm-intel:
drm/i915: set GFX_MODE to pre-Ivybridge default value even on Ivybridge
There is a race between ext4 buffer write and direct_IO read with
dioread_nolock mount option enabled. The problem is that we clear
PageWriteback flag during end_io time but will do
uninitialized-to-initialized extent conversion later with dioread_nolock.
If an O_direct read request comes in during this period, ext4 will return
zero instead of the recently written data.
This patch checks whether there are any pending uninitialized-to-initialized
extent conversion requests before doing O_direct read to close the race.
Note that this is just a bandaid fix. The fundamental issue is that we
clear PageWriteback flag before we really complete an IO, which is
problem-prone. To fix the fundamental issue, we may need to implement an
extent tree cache that we can use to look up pending to-be-converted extents.
Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Prior to Ivybridge, the GFX_MODE would default to 0x800, meaning that
MI_FLUSH would flush the TLBs in addition to the rest of the caches
indicated in the MI_FLUSH command. However starting with Ivybridge, the
register defaults to 0x2800 out of reset, meaning that to invalidate the
TLB we need to use PIPE_CONTROL. Since we're not doing that yet, go
back to the old default so things work.
v2: don't forget to actually *clear* the new bit
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
* 'for-linus' of git://git.kernel.dk/linux-block: (23 commits)
Revert "cfq: Remove special treatment for metadata rqs."
block: fix flush machinery for stacking drivers with differring flush flags
block: improve rq_affinity placement
blktrace: add FLUSH/FUA support
Move some REQ flags to the common bio/request area
allow blk_flush_policy to return REQ_FSEQ_DATA independent of *FLUSH
xen/blkback: Make description more obvious.
cfq-iosched: Add documentation about idling
block: Make rq_affinity = 1 work as expected
block: swim3: fix unterminated of_device_id table
block/genhd.c: remove useless cast in diskstats_show()
drivers/cdrom/cdrom.c: relax check on dvd manufacturer value
drivers/block/drbd/drbd_nl.c: use bitmap_parse instead of __bitmap_parse
bsg-lib: add module.h include
cfq-iosched: Reduce linked group count upon group destruction
blk-throttle: correctly determine sync bio
loop: fix deadlock when sysfs and LOOP_CLR_FD race against each other
loop: add BLK_DEV_LOOP_MIN_COUNT=%i to allow distros 0 pre-allocated loop devices
loop: add management interface for on-demand device allocation
loop: replace linked list of allocated devices with an idr index
...
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
PCI: OF: Don't crash when bridge parent is NULL.
PCI: export pcie_bus_configure_settings symbol
PCI: code and comments cleanup
PCI: make cardbus-bridge resources optional
PCI: make SRIOV resources optional
PCI : ability to relocate assigned pci-resources
PCI: honor child buses add_size in hot plug configuration
PCI: Set PCI-E Max Payload Size on fabric
Add linux/module.h to fix this compilation error:
drivers/power/s3c_adc_battery.c:435:15: error: expected declaration specifiers or ‘...’ before string constant
drivers/power/s3c_adc_battery.c:435:1: warning: data definition has no type or storage class
drivers/power/s3c_adc_battery.c:435:1: warning: type defaults to ‘int’ in declaration of ‘MODULE_AUTHOR’
drivers/power/s3c_adc_battery.c:435:15: warning: function declaration isn’t a prototype
drivers/power/s3c_adc_battery.c:436:20: error: expected declaration specifiers or ‘...’ before string constant
drivers/power/s3c_adc_battery.c:436:1: warning: data definition has no type or storage class
drivers/power/s3c_adc_battery.c:436:1: warning: type defaults to ‘int’ in declaration of ‘MODULE_DESCRIPTION’
drivers/power/s3c_adc_battery.c:436:20: warning: function declaration isn’t a prototype
drivers/power/s3c_adc_battery.c:437:16: error: expected declaration specifiers or ‘...’ before string constant
drivers/power/s3c_adc_battery.c:437:1: warning: data definition has no type or storage class
drivers/power/s3c_adc_battery.c:437:1: warning: type defaults to ‘int’ in declaration of ‘MODULE_LICENSE’
drivers/power/s3c_adc_battery.c:437:16: warning: function declaration isn’t a prototype
make[2]: *** [drivers/power/s3c_adc_battery.o] Error 1
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Ian Lartey <ian@opensource.wolfsonmicro.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
power/max8997_charger.c uses interfaces from linux/module.h,
so it should include that file. This fixes build errors.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
power/max8998_charger.c uses interfaces from linux/module.h,
so it should include that file. This fixes build errors.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
In pcibios_get_phb_of_node(), we will crash while booting if
bus->bridge->parent is NULL.
Check for this case and avoid dereferencing the NULL pointer.
Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Instead of printing something non-formatted to stdout, call
man(1) to show the man page for the proper subcommand.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Loosely based on a patch for cpufrequtils, submittted by
Sergey Dryabzhinsky <sergey.dryabzhinsky@gmail.com> and
signed-off-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Revert the pass-good area introduced in ffd1f609ab ("writeback:
introduce max-pause and pass-good dirty limits") and make the max-pause
area smaller and safe.
This fixes ~30% performance regression in the ext3 data=writeback
fio_mmap_randwrite_64k/fio_mmap_randrw_64k test cases, where there are
12 JBOD disks, on each disk runs 8 concurrent tasks doing reads+writes.
Using deadline scheduler also has a regression, but not that big as CFQ,
so this suggests we have some write starvation.
The test logs show that
- the disks are sometimes under utilized
- global dirty pages sometimes rush high to the pass-good area for
several hundred seconds, while in the mean time some bdi dirty pages
drop to very low value (bdi_dirty << bdi_thresh). Then suddenly the
global dirty pages dropped under global dirty threshold and bdi_dirty
rush very high (for example, 2 times higher than bdi_thresh). During
which time balance_dirty_pages() is not called at all.
So the problems are
1) The random writes progress so slow that they break the assumption of
the max-pause logic that "8 pages per 200ms is typically more than
enough to curb heavy dirtiers".
2) The max-pause logic ignored task_bdi_thresh and thus opens the possibility
for some bdi's to over dirty pages, leading to (bdi_dirty >> bdi_thresh)
and then (bdi_thresh >> bdi_dirty) for others.
3) The higher max-pause/pass-good thresholds somehow leads to the bad
swing of dirty pages.
The fix is to allow the task to slightly dirty over task_bdi_thresh, but
no way to exceed bdi_dirty and/or global dirty_thresh.
Tests show that it fixed the JBOD regression completely (both behavior
and performance), while still being able to cut down large pause times
in balance_dirty_pages() for single-disk cases.
Reported-by: Li Shaohua <shaohua.li@intel.com>
Tested-by: Li Shaohua <shaohua.li@intel.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
IPV6_2292PKTOPTIONS is broken for 32-bit applications running
in COMPAT mode on 64-bit kernels.
The same problem was fixed for IPv4 with the patch:
ipv4: Fix ip_getsockopt for IP_PKTOPTIONS,
commit dd23198e58
Signed-off-by: Sorin Dumitru <sdumitru@ixiacom.com>
Signed-off-by: Daniel Baluta <dbaluta@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We have a kernel build regression since 3.1-rc1, which is about 10%
regression. The kernel source is in an ext3 filesystem.
Alex Shi bisect it to commit:
commit a07405b780
Author: Justin TerAvest <teravest@google.com>
Date: Sun Jul 10 22:09:19 2011 +0200
cfq: Remove special treatment for metadata rqs.
Apparently this is caused by lack metadata preemption, where ext3/ext4
do use READ_META. I didn't see a way to fix the issue, so suggest
reverting the patch.
This reverts commit a07405b780.
Reported-by: Alex Shi<alex.shi@intel.com>
Reported-by: Shaohua Li<shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The recent fix for testing dB range at the mixer creation time seems
to cause regressions in some devices. In such devices, reading the dB
info at probing time gives an error, thus both dBmin and dBmax are still
zero, and TLV flag isn't set although the later read of dB info succeeds.
This patch adds a workaround for such a case by assuming that the later
read will succeed. In future, a similar test should be performed in a
case where a wrong dB range is seen even in the later read.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: <stable@kernel.org>
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
NFSv4.1: Return NFS4ERR_BADSESSION to callbacks during session resets
NFSv4.1: Fix the callback 'highest_used_slotid' behaviour
pnfs-obj: Fix the comp_index != 0 case
pnfs-obj: Bug when we are running out of bio
nfs: add missing prefetch.h include
CC arch/sparc/kernel/pcic.o
arch/sparc/kernel/pcic.c: In function 'pcic_probe':
arch/sparc/kernel/pcic.c:359:33: error: array subscript is above array bounds [-Werror=array-bounds]
arch/sparc/kernel/pcic.c:359:8: error: array subscript is above array bounds [-Werror=array-bounds]
arch/sparc/kernel/pcic.c:360:33: error: array subscript is above array bounds [-Werror=array-bounds]
arch/sparc/kernel/pcic.c:360:8: error: array subscript is above array bounds [-Werror=array-bounds]
arch/sparc/kernel/pcic.c:361:33: error: array subscript is above array bounds [-Werror=array-bounds]
arch/sparc/kernel/pcic.c:361:8: error: array subscript is above array bounds [-Werror=array-bounds]
cc1: all warnings being treated as errors
I'm not particularly familiar with sparc but t_nmi (defined in head_32.S via
the TRAP_ENTRY macro) and pcic_nmi_trap_patch (defined in entry.S) both appear
to be 4 instructions long and I presume from the usage that instructions are
int sized.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Update netdev-features.txt entry in 00-INDEX to incorporate
feedback by Michał Mirosław.
v2: restored tabs that were inadvertently changed to spaces in v1.
sorry for the error.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
It's after all necessary to do reset headers here. The reason is we
cannot depend that it gets reseted in __netif_receive_skb once skb is
reinjected. For incoming vlanids without vlan_dev, vlan_do_receive()
returns false with skb != NULL and __netif_reveive_skb continues, skb is
not reinjected.
This might be good material for 3.0-stable as well
Reported-by: Mike Auty <mike.auty@gmail.com>
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, error handling code in this function calls the function
sata_dwc_port_stop, but this function has essentially no effect if hsdevp
has not been stored in ap, which is the case throughout this function. The
only effect is to print a debugging message including ap->print_id.
The code is rewritten to not call sata_dwc_port_stop, but instead to jump
to a local label that prints the original error message and the print_id
information. In the case where hsdevp has been already allocated (but not
yet stored in ap), this value is freed as well.
A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)
// <smpl>
@exists@
local idexpression x;
statement S,S1;
expression E;
identifier fl;
expression *ptr != NULL;
@@
x = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
when != if (...) { <+...kfree(x)...+> }
when any
when != true x == NULL
x->fl
...>
(
if (x == NULL) S1
|
if (...) { ... when != x
when forall
(
return \(0\|<+...x...+>\|ptr\);
|
* return ...;
)
}
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Add basic support for pata on iMX. It has been tested only on imx51.
SDMA support will probably be added later so this version supports only
PIO.
v2:
- enable only when needed IORDY
- use dev_get_drvdata
v3:
- add missing clk_put() calls
- use platform_get_irq()
- fix resume code to avoid disabling IORDY on resume
v4:
- Remove EXPERIMENTAL and switch to depends on ARCH_MXC
- Use devm_kzalloc()
- make clock a must-have
- Use only 1 ioremap
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
On AVERATEC 3200, pata_via causes memory corruption with ATAPI DMA,
which often leads to random kernel oops. The cause of the problem is
not well understood yet and only small subset of machines using the
controller seem affected. Blacklist ATAPI DMA on the machine.
Signed-off-by: Tejun Heo <tj@kernel.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=11426
Reported-and-tested-by: Jim Bray <jimsantelmo@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Init 'serror' to silence the following warning:
drivers/ata/sata_sil.c: In function ‘sil_interrupt’:
drivers/ata/sata_sil.c:453:14: warning: ‘serror’ may be used uninitialized in
this function [-Wuninitialized]
This is not a 'can never happen' but is nonetheless extremely unlikely.
The easiest and cleanest warning fix is simply to init the var,
rather than worry about marking the var uninit-ok.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
Btrfs: set i_size properly when fallocating and we already
btrfs: unlock on error in btrfs_file_llseek()
btrfs: btrfs_permission's RO check shouldn't apply to device nodes
Btrfs: truncate pages from clone ioctl target range
Btrfs: fix uninitialized sync_pending
Btrfs: fix wrong free space information
btrfs: memory leak in btrfs_add_inode_defrag()
Btrfs: use plain page_address() in header fields setget functions
Btrfs: forced readonly when btrfs_drop_snapshot() fails
Btrfs: check if there is enough space for balancing smarter
Btrfs: fix a bug of balance on full multi-disk partitions
Btrfs: fix an oops of log replay
Btrfs: detect wether a device supports discard
Btrfs: force unplugs when switching from high to regular priority bios
