fc_destroy_bsgjob() and bsg_destroy_job() are now 1:1 copies, so use the
latter. As bsg_destroy_job() comes from bsg-lib we need to select it in
Kconfig once CONFOG_SCSI_FC_ATTRS is active.
Signed-off-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver was changed to call ioport_map, which breaks platforms that
cannot provide this function:

drivers/scsi/g_NCR5380.o: In function `generic_NCR5380_init_one.constprop.0':
g_NCR5380.c:(.text.generic_NCR5380_init_one.constprop.0+0x388): undefined reference to `ioport_map'

This adds a Kconfig dependency.

Fixes: 04c40f82ccc5 ("scsi: g_NCR5380: Merge g_NCR5380 and g_NCR5380_mmio drivers")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Merge the port-mapped IO and memory-mapped IO support (with the help of
ioport_map) into the g_NCR5380 module and delete g_NCR5380_mmio.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver has not seen any maintainer activity or other work that
wasn't tree wide conversion or clenaups in the entire history of
the git tree.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Acked-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver has not seen any maintainer activity or other work that
wasn't tree wide conversion or clenaups in the entire history of
the git tree.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Acked-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver has not seen any maintainer activity or other work that
wasn't tree wide conversion or clenaups in the entire history of
the git tree.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Acked-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver has not seen any maintainer activity or other work that
wasn't tree wide conversion or clenaups in the entire history of
the git tree.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver has not seen any maintainer activity or other work that
wasn't tree wide conversion or clenaups in the entire history of
the git tree.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver has not seen any maintainer activity or other work that
wasn't tree wide conversion or clenaups in the entire history of
the git tree.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The driver has not seen any maintainer activity or other work that
wasn't tree wide conversion or clenaups in the entire history of
the git tree.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This initial commit contains Microsemi's smartpqi module.

[mkp: Minor tweaks to apply to 4.9/scsi-queue]
Reviewed-by: NScott Benesh <scott.benesh@microsemi.com>
Reviewed-by: NKevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: NKevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: NDon Brace <don.brace@microsemi.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NEwan D. Milne <emilne@redhat.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This driver is a pick up of the old IBM VIO scsi Target Driver
that was started by Nick and Fujita 2-4 years ago.
http://comments.gmane.org/gmane.linux.scsi/90119

The driver provides a virtual SCSI device on IBM Power Servers.

This patch contains the fifth version for an initial merge of the
tcm ibmvscsis driver. More information on this driver and config
can be found:

https://github.com/powervm/ibmvscsis/wiki/Configuration
http://www.linux-iscsi.org/wiki/IBM_vSCSI

(Drop extra libsrp review breakage + Fix kconfig typo - nab)
Signed-off-by: NSteven Royer <seroyer@linux.vnet.ibm.com>
Signed-off-by: NTyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: NMichael Cyr <mikecyr@linux.vnet.ibm.com>
Signed-off-by: NBryant G. Ly <bryantly@linux.vnet.ibm.com>
Cc: FUJITA Tomonori <tomof@acm.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Fix build when CONFIG_ISA_DMA_API is not enabled. Fixes these build
errors (on x86_64):

../drivers/scsi/ultrastor.c: In function 'ultrastor_14f_detect':
../drivers/scsi/ultrastor.c:519:5: error: implicit declaration of function 'request_dma' [-Werror=implicit-function-declaration]
     if (config.dma_channel && request_dma(config.dma_channel,"Ultrastor")) {
     ^
../drivers/scsi/ultrastor.c: In function 'ultrastor_release':
../drivers/scsi/ultrastor.c:658:3: error: implicit declaration of function 'free_dma' [-Werror=implicit-function-declaration]
   free_dma(shost->dma_channel);
   ^
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Now it's ready to move the mempool based SG chained allocator code from
SCSI driver to lib/sg_pool.c, which will be compiled only based on a Kconfig
symbol CONFIG_SG_POOL.

SCSI selects CONFIG_SG_POOL.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMing Lin <ming.l@ssi.samsung.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This change brings a number of improvements: fewer macros, better test
coverage, simpler code and sane Kconfig options. The downside is a small
chance of incompatibility (which seems unavoidable).

CONFIG_SCSI_GENERIC_NCR53C400 exists to enable or inhibit pseudo DMA
transfers when the driver is used with 53C400-compatible cards. Thanks to
Ondrej Zary's patches, PDMA now works which means it can be enabled
unconditionally.

Due to bad design, CONFIG_SCSI_GENERIC_NCR53C400 ties together unrelated
functionality as it sets both PSEUDO_DMA and BIOSPARAM macros. This patch
effectively enables PSEUDO_DMA and disables BIOSPARAM.

The defconfigs and the Kconfig default leave CONFIG_SCSI_GENERIC_NCR53C400
undefined. Red Hat 9 and CentOS 2.1 were the same. This leaves both
PSEUDO_DMA and BIOSPARAM disabled. The effect of this patch should be
better performance from enabling PSEUDO_DMA.

On the other hand, Debian 4 and SLES 10 had CONFIG_SCSI_GENERIC_NCR53C400
enabled, so both PSEUDO_DMA and BIOSPARAM were enabled. This patch might
affect configurations like this by disabling BIOSPARAM. My best guess is
that this could be a problem only in the vanishingly rare case that
1) the CHS values stored in the boot device partition table are wrong and
2) a 5380 card is in use (because PDMA on 53C400 used to be broken).
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

On 64 bit, struct error_info has 6 bytes of padding, which amounts to
over 4k of wasted space in the additional[] array. We could easily get
rid of that by instead using separate arrays for the codes and the
pointers. However, we can do even better than that and save an
additional 6 bytes per entry: In the table, just store the sizeof()
the corresponding string literal. The cumulative sum of these is then
the appropriate offset into additional_text, which is built from the
concatenation (with '\0's inbetween) of the strings.

$ scripts/bloat-o-meter /tmp/vmlinux vmlinux
add/remove: 0/0 grow/shrink: 1/1 up/down: 24/-8488 (-8464)
function                                     old     new   delta
scsi_extd_sense_format                       136     160     +24
additional                                 11312    2824   -8488

The Kconfig help text used to say that CONFIG_SCSI_CONSTANTS=y costs
around 75 KB, but that was a little exaggerated. The actual number was
closer to 44K, and 36K with this patch.
Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

tree:   https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fgit.kernel.org%2fpub%2fscm%2flinux%2fkernel%2fgit%2ftorvalds%2flinux.git&data=01%7c01%7ckys%40microsoft.com%7ce2e0622715844b79ad7108d32796ec3c%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=ubr4GbBaNS%2ftOz%2buJBk0CL9N0UNG9x2TidLgy6Yovg4%3d master
head:   03c21cb7
commit: dac58241 storvsc: Properly support Fibre Channel devices
date:   3 weeks ago
config: x86_64-randconfig-s3-01281016 (attached as .config)
reproduce:
        git checkout dac58241
        # save the attached .config to linux build tree
        make ARCH=x86_64

All errors (new ones prefixed by >>):

   drivers/built-in.o: In function `storvsc_remove':
>> storvsc_drv.c:(.text+0x213af7): undefined reference to `fc_remove_host'
   drivers/built-in.o: In function `storvsc_drv_init':
>> storvsc_drv.c:(.init.text+0xcbcc): undefined reference to `fc_attach_transport'
>> storvsc_drv.c:(.init.text+0xcc06): undefined reference to `fc_release_transport'
   drivers/built-in.o: In function `storvsc_drv_exit':
>> storvsc_drv.c:(.exit.text+0x123c): undefined reference to `fc_release_transport'

With this commit, the storvsc driver depends on FC atttributes. Make this
dependency explicit.
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The atari_NCR5380.c core driver now takes care of bus reset upon driver
initialization if required (same as NCR5380.c). Move the Toshiba CD-ROM
support into the core driver, enabled with a host flag, so that all
NCR5380 drivers can make use of it.

Drop the RESET_BOOT macros and the ATARI_SCSI_RESET_BOOT and
ATARI_SCSI_TOSHIBA_DELAY Kconfig symbols, which are now redundant.

Remove the atari_scsi_reset_boot(), mac_scsi_reset_boot() and
sun3_scsi_reset_boot() routines. None of this duplicated code is needed
now that all drivers can use NCR5380_maybe_reset_bus().

This brings atari_scsi, mac_scsi and sun3_scsi into line with all of the
other NCR5380 drivers.

The bus reset may raise an interrupt. That would be new behaviour for
atari_scsi only when CONFIG_ATARI_SCSI_RESET_BOOT=n. The ST DMA interrupt
is not assigned to atari_scsi at this stage, so
CONFIG_ATARI_SCSI_RESET_BOOT=y may well be problematic already.
Regardless, do_reset() now raises and clears the interrupt within
local_irq_save/restore which should avoid problems.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The current discovery routines use the VPD 0x83 inquiry page to find
the device SAS address and match it to the end point in the enclosure.
This doesn't work for SATA devices because expanders (or hosts) simply
make up an endpoint address for STP and thus the address returned by
the VPD page never matches.  Instead of doing this, for SAS attached
devices, match by the direct endpoint address instead.
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

The new name is irq_poll as iopoll is already taken.  Better suggestions
welcome.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>

This patch adds the initial bare main driver for the HiSilicon SAS
HBA. This only introduces the changes to build and load the main driver
module.

The complete driver consists of the core main module and also a module
platform driver for driving the hw.

The HBA is a platform device.
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Signed-off-by: NZhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The hpsa driver recently started using the sas transport class, but it
does not ensure that the corresponding code is actually built, which
may lead to a link error:

drivers/built-in.o: In function `hpsa_free_sas_phy':
(.text+0x1ce874): undefined reference to `sas_port_delete_phy'
(.text+0x1ce87c): undefined reference to `sas_phy_free'
drivers/built-in.o: In function `hpsa_alloc_sas_port':
(.text+0x1ceb9c): undefined reference to `sas_port_alloc_num'
(.text+0x1ceba8): undefined reference to `sas_port_add'
drivers/built-in.o: In function `hpsa_init':
(.init.text+0x8838): undefined reference to `sas_attach_transport'
(.init.text+0x8868): undefined reference to `sas_release_transport

This adds 'select SCSI_SAS_ATTR' in the Kconfig entry, just like we do
for all other drivers using those functions.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Fixes: d04e62b9 ("hpsa: add in sas transport class")
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The advansys drvier uses the request_dma function that is used on ISA
machines for the internal DMA controller, which causes build errors
on platforms that have ISA slots but do not provide the ISA DMA API:

drivers/scsi/advansys.c: In function 'advansys_board_found':
drivers/scsi/advansys.c:11300:10: error: implicit declaration of function 'request_dma' [-Werror=implicit-function-declaration]

The problem now showed up in ARM randconfig builds after commit
6571fb3f ("advansys: Update to version 3.5 and remove compilation
warning") made it possible to build on platforms that have neither
VIRT_TO_BUS nor ISA_DMA_API but that do have ISA.

This adds the missing dependency.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Modified the mpt3sas driver to have a single driver module which
supports both SAS 2.0 & SAS 3.0 HBA devices.

* Added SAS 2.0 HBA device IDs to the mpt3sas_pci_table pci table.

* Created two separate SCSI host templates for SAS2 and SAS3 HBAs so
  that, during the driver load time driver can use corresponding host
  template(based the pci device ID) while registering a scsi host
  adapter instance for that pci device.

* Registered two IOCTL devices, mpt2ctl is for SAS2 HBAs & mpt3ctl for
  SAS3 HBAs. Also updated the code to make sure that mpt2ctl device
  processes only those ioctl cmds issued for the SAS2 HBAs and mpt3ctl
  device processes only those ioctl cmds issued for the SAS3 HBAs.

* Added separate indexing for SAS2 and SAS3 HBAs.

* Replaced compile time check 'MPT2SAS_SCSI' to run time check
  'hba_mpi_version_belonged' whereever needed.

* Aliased this merged driver to mpt2sas using MODULE_ALIAS.

* Moved global varaible 'driver_name' to per adapter instance variable.

* Created two raid function template and used corresponding raid
  function templates based on the run time check
  'hba_mpi_version_belonged'.

* Moved mpt2sas_warpdrive.c file from mpt2sas to mpt3sas folder and
  renamed it as mpt3sas_warpdrive.c.

* Also renamed the functions in mpt3sas_warpdrive.c file to follow
  current driver function name convention.

* Updated the Makefile to build mpt3sas_warpdrive.o file for these
  WarpDrive-specific functions.

* Also in function mpt3sas_setup_direct_io(), used sector_div() API
  instead of division operator (which gives compilation errors on 32 bit
  machines).

* Removed mpt2sas files, mpt2sas directory & mpt3sas_module.c file.

* Added module parameter 'hbas_to_enumerate' which permits using this
  merged driver as a legacy mpt2sas driver or as a legacy mpt3sas
  driver.

  Here are the available options for this module parameter:

   0 - Merged driver which enumerates both SAS 2.0 & SAS 3.0 HBAs
   1 - Acts as legacy mpt2sas driver, which enumerates only SAS 2.0 HBAs
   2 - Acts as legacy mpt3sas driver, which enumerates only SAS 3.0 HBAs

* Removed mpt2sas entries from SCSI's Kconfig and Makefile files.
Signed-off-by: NSreekanth Reddy <Sreekanth.Reddy@avagotech.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This module has been removed in commit 6072609d
([SCSI] Remove scsi_wait_scan module), so this module is gone since 3.6.
Signed-off-by: NRolf Eike Beer <eike-kernel@sf-tec.de>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

SCSI device driver to support filesystem access on the IBM CXL Flash adapter.
Supported-by: NStephen Bates <stephen.bates@pmcs.com>
Reviewed-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NManoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: NBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

Cisco has developed a new PCI HBA interface called sNIC, which stands for
SCSI NIC. This is a new storage feature supported on specialized network
adapter. The new PCI function provides a uniform host interface and abstracts
backend storage.

[jejb: fix up checkpatch errors]
Signed-off-by: NNarsimhulu Musini <nmusini@cisco.com>
Signed-off-by: NSesidhar Baddela <sebaddel@cisco.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

This patch fix spelling typos in Kconfig.
Signed-off-by: NMasanari Iida <standby24x7@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

The driver has now been converted to DMA-API, so we should
increase the version number and remove the compilation
warning.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

Only required if the dma buffer has been allocated via
dma_alloc_noncoherent(), which this one is not.
With that call removed we can now also compile on ARM.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

T10 PI is just another optional feature, LLDDs should work without
the infrastructure.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

Instead of having constants.c littered with ifdef statements we should
be moving dummy functions into the header and condintionally compile in
constants.c if selected. And update the Kconfig description to reflect
the actual size difference.
Suggested-by: NChristoph Hellwig <hch@infradead.org>
Tested-by: NRobert Elliott <elliott@hp.com>
Reviewed-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Try to give a more accurate driver description and some extra
information in less lines.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: NEwan D. Milne <emilne@redhat.com>

Introduce wd719x, a driver for Western Digital WD7193, WD7197 and WD7296 PCI
SCSI controllers based on WD33C296A chip.
Tested with WD7193 card.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The am53c974 is a re-implementation of the tmscsim driver,
and provides the same functionality.
So remove the tmscsim driver and make am53c974 an alias to tmscsim.
Acked-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

This patch adds a new implementation for the Tekram DC-390T /
AMD AM53c974 SCSI controller, based on the generic
esp_scsi infrastructure.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Allow mac_scsi to be built as a module. Replace the old validation of
__setup options with code that validates both module and __setup options.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The pvscsi frontend driver requires the xenbus frontend driver. Reflect
this in Kconfig.
Signed-off-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

Add a Kconfig option to enable the blk-mq path for SCSI by default
to ease testing and deployment in setups that know they benefit
from blk-mq.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NRobert Elliott <elliott@hp.com>
Tested-by: NRobert Elliott <elliott@hp.com>

The T10 Protection Information format is also used by some devices that
do not go through the SCSI layer (virtual block devices, NVMe). Relocate
the relevant functions to a block layer library that can be used without
involving SCSI.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>