<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/drivers/mmc/core/queue.c, branch v4.14.263</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v4.14.263</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v4.14.263'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2020-10-14T07:51:14+00:00</updated>
<entry>
<title>mmc: core: don't set limits.discard_granularity as 0</title>
<updated>2020-10-14T07:51:14+00:00</updated>
<author>
<name>Coly Li</name>
<email>colyli@suse.de</email>
</author>
<published>2020-10-02T01:38:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=387026b76afb69a349bc5aa7e18fa9ef4aa0bd23'/>
<id>urn:sha1:387026b76afb69a349bc5aa7e18fa9ef4aa0bd23</id>
<content type='text'>
[ Upstream commit 4243219141b67d7c2fdb2d8073c17c539b9263eb ]

In mmc_queue_setup_discard() the mmc driver queue's discard_granularity
might be set as 0 (when card-&gt;pref_erase &gt; max_discard) while the mmc
device still declares to support discard operation. This is buggy and
triggered the following kernel warning message,

WARNING: CPU: 0 PID: 135 at __blkdev_issue_discard+0x200/0x294
CPU: 0 PID: 135 Comm: f2fs_discard-17 Not tainted 5.9.0-rc6 #1
Hardware name: Google Kevin (DT)
pstate: 00000005 (nzcv daif -PAN -UAO BTYPE=--)
pc : __blkdev_issue_discard+0x200/0x294
lr : __blkdev_issue_discard+0x54/0x294
sp : ffff800011dd3b10
x29: ffff800011dd3b10 x28: 0000000000000000 x27: ffff800011dd3cc4 x26: ffff800011dd3e18 x25: 000000000004e69b x24: 0000000000000c40 x23: ffff0000f1deaaf0 x22: ffff0000f2849200 x21: 00000000002734d8 x20: 0000000000000008 x19: 0000000000000000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000394 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 00000000000008b0 x9 : ffff800011dd3cb0 x8 : 000000000004e69b x7 : 0000000000000000 x6 : ffff0000f1926400 x5 : ffff0000f1940800 x4 : 0000000000000000 x3 : 0000000000000c40 x2 : 0000000000000008 x1 : 00000000002734d8 x0 : 0000000000000000 Call trace:
__blkdev_issue_discard+0x200/0x294
__submit_discard_cmd+0x128/0x374
__issue_discard_cmd_orderly+0x188/0x244
__issue_discard_cmd+0x2e8/0x33c
issue_discard_thread+0xe8/0x2f0
kthread+0x11c/0x120
ret_from_fork+0x10/0x1c
---[ end trace e4c8023d33dfe77a ]---

This patch fixes the issue by setting discard_granularity as SECTOR_SIZE
instead of 0 when (card-&gt;pref_erase &gt; max_discard) is true. Now no more
complain from __blkdev_issue_discard() for the improper value of discard
granularity.

This issue is exposed after commit b35fd7422c2f ("block: check queue's
limits.discard_granularity in __blkdev_issue_discard()"), a "Fixes:" tag
is also added for the commit to make sure people won't miss this patch
after applying the change of __blkdev_issue_discard().

Fixes: e056a1b5b67b ("mmc: queue: let host controllers specify maximum discard timeout")
Fixes: b35fd7422c2f ("block: check queue's limits.discard_granularity in __blkdev_issue_discard()").
Reported-and-tested-by: Vicente Bergas &lt;vicencb@gmail.com&gt;
Signed-off-by: Coly Li &lt;colyli@suse.de&gt;
Acked-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
Link: https://lore.kernel.org/r/20201002013852.51968-1-colyli@suse.de
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mmc: block: Delete mmc_access_rpmb()</title>
<updated>2020-01-12T11:12:03+00:00</updated>
<author>
<name>Linus Walleij</name>
<email>linus.walleij@linaro.org</email>
</author>
<published>2017-09-20T08:02:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=ae4e8ce0d86159bbba7cfaa44f6276d38b1f2200'/>
<id>urn:sha1:ae4e8ce0d86159bbba7cfaa44f6276d38b1f2200</id>
<content type='text'>
commit 14f4ca7e4d2825f9f71e22905ae177b899959f1d upstream.

This function is used by the block layer queue to bail out of
requests if the current request is towards an RPMB
"block device".

This was done to avoid boot time scanning of this "block
device" which was never really a block device, thus duct-taping
over the fact that it was badly engineered.

This problem is now gone as we removed the offending RPMB block
device in another patch and replaced it with a character
device.

Cc: Tomas Winkler &lt;tomas.winkler@intel.com&gt;
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
Cc: Jisheng Zhang &lt;Jisheng.Zhang@synaptics.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>mmc: Delete bounce buffer handling</title>
<updated>2017-10-04T08:22:55+00:00</updated>
<author>
<name>Linus Walleij</name>
<email>linus.walleij@linaro.org</email>
</author>
<published>2017-09-20T08:56:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=de3ee99b097dd51938276e3af388cd4ad0f2750a'/>
<id>urn:sha1:de3ee99b097dd51938276e3af388cd4ad0f2750a</id>
<content type='text'>
In may, Steven sent a patch deleting the bounce buffer handling
and the CONFIG_MMC_BLOCK_BOUNCE option.

I chose the less invasive path of making it a runtime config
option, and we merged that successfully for kernel v4.12.

The code is however just standing in the way and taking up
space for seemingly no gain on any systems in wide use today.

Pierre says the code was there to improve speed on TI SDHCI
controllers on certain HP laptops and possibly some Ricoh
controllers as well. Early SDHCI controllers lacked the
scatter-gather feature, which made software bounce buffers
a significant speed boost.

We are clearly talking about the list of SDHCI PCI-based
MMC/SD card readers found in the pci_ids[] list in
drivers/mmc/host/sdhci-pci-core.c.

The TI SDHCI derivative is not supported by the upstream
kernel. This leaves the Ricoh.

What we can however notice is that the x86 defconfigs in the
kernel did not enable CONFIG_MMC_BLOCK_BOUNCE option, which
means that any such laptop would have to have a custom
configured kernel to actually take advantage of this
bounce buffer speed-up. It simply seems like there was
a speed optimization for the Ricoh controllers that noone
was using. (I have not checked the distro defconfigs but
I am pretty sure the situation is the same there.)

Bounce buffers increased performance on the OMAP HSMMC
at one point, and was part of the original submission in
commit a45c6cb81647 ("[ARM] 5369/1: omap mmc: Add new
   omap hsmmc controller for 2430 and 34xx, v3")

This optimization was removed in
commit 0ccd76d4c236 ("omap_hsmmc: Implement scatter-gather
   emulation")
which found that scatter-gather emulation provided even
better performance.

The same was introduced for SDHCI in
commit 2134a922c6e7 ("sdhci: scatter-gather (ADMA) support")

I am pretty positively convinced that software
scatter-gather emulation will do for any host controller what
the bounce buffers were doing. Essentially, the bounce buffer
was a reimplementation of software scatter-gather-emulation in
the MMC subsystem, and it should be done away with.

Cc: Pierre Ossman &lt;pierre@ossman.eu&gt;
Cc: Juha Yrjola &lt;juha.yrjola@solidboot.com&gt;
Cc: Steven J. Hill &lt;Steven.Hill@cavium.com&gt;
Cc: Shawn Lin &lt;shawn.lin@rock-chips.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Suggested-by: Steven J. Hill &lt;Steven.Hill@cavium.com&gt;
Suggested-by: Shawn Lin &lt;shawn.lin@rock-chips.com&gt;
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
</content>
</entry>
<entry>
<title>mmc: block: Fix incorrectly initialized requests</title>
<updated>2017-09-08T13:37:51+00:00</updated>
<author>
<name>Adrian Hunter</name>
<email>adrian.hunter@intel.com</email>
</author>
<published>2017-09-07T07:40:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=01f5bbd17a8066b58dba9b5049fad504bce67322'/>
<id>urn:sha1:01f5bbd17a8066b58dba9b5049fad504bce67322</id>
<content type='text'>
mmc_init_request() depends on card-&gt;bouncesz so it must be calculated
before blk_init_allocated_queue() starts allocating requests.

Reported-by: Seraphime Kirkovski &lt;kirkseraph@gmail.com&gt;
Fixes: 304419d8a7e9 ("mmc: core: Allocate per-request data using the..")
Signed-off-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Tested-by: Seraphime Kirkovski &lt;kirkseraph@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
Tested-by: Pavel Machek &lt;pavel@ucw.cz&gt;
</content>
</entry>
<entry>
<title>Merge tag 'mmc-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc</title>
<updated>2017-07-04T18:11:56+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-07-04T18:11:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=17ece345a042347224e50032e959ad3959638b21'/>
<id>urn:sha1:17ece345a042347224e50032e959ad3959638b21</id>
<content type='text'>
Pull MMC updates from Ulf Hansson:
 "MMC core:
   - Add support to enable irq wake for slot gpio
   - Remove MMC_CAP2_HC_ERASE_SZ and make it the default behaviour
   - Improve R1 response error checks for stop commands
   - Cleanup and clarify some MMC specific code
   - Keep card runtime resumed while adding SDIO function devices
   - Use device_property_read instead of of_property_read in mmc_of_parse()
   - Move boot partition locking into a driver op to enable proper I/O scheduling
   - Move multi/single-ioctl() to use block layer to enable proper I/O scheduling
   - Delete bounce buffer Kconfig option
   - Improve the eMMC HW reset support provided via the eMMC pwrseq
   - Add host API to manage SDIO IRQs from a workqueue

  MMC host:
   - dw_mmc: Drop support for multiple slots
   - dw_mmc: Use device_property_read instead of of_property_read
   - dw_mmc-rockchip: Optional improved tuning to greatly decrease tuning time
   - dw_mmc: Prevent rpm suspend for SDIO IRQs instead of always for SDIO cards
   - dw_mmc: Convert to use MMC_CAP2_SDIO_IRQ_NOTHREAD for SDIO IRQs
   - omap_hsmmc: Convert to mmc regulator APIs to consolidate code
   - omap_hsmmc: Deprecate "vmmc_aux" in DT and use "vqmmc" instead
   - tmio: make sure SDIO gets reinitialized after resume
   - sdhi: add CMD23 support to R-Car Gen2 &amp; Gen3
   - tmio: add CMD23 support
   - sdhi/tmio: Refactor code and rename files to simplify Kconfig options
   - sdhci-pci: Enable card detect wake for Intel BYT-related SD controllers
   - sdhci-pci: Add support for Intel CNP
   - sdhci-esdhc-imx: Remove ENGcm07207 workaround - allow multi block transfers
   - sdhci-esdhc-imx: Allow all supported prescaler values
   - sdhci-esdhc-imx: Fix DAT line software reset
   - sdhci-esdhc: Add SDHCI_QUIRK_32BIT_DMA_ADDR
   - atmel-mci: Drop AVR32 support"

* tag 'mmc-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc: (86 commits)
  mmc: dw_mmc: remove the unnecessary slot variable
  mmc: dw_mmc: use the 'slot' instead of 'cur_slot'
  mmc: dw_mmc: remove the 'id' arguments about functions relevant to slot
  mmc: dw_mmc: change the array of slots
  mmc: dw_mmc: remove the loop about finding slots
  mmc: dw_mmc: deprecated the "num-slots" property
  mmc: dw_mmc-rockchip: parse rockchip, desired-num-phases from DT
  dt-bindings: rockchip-dw-mshc: add optional rockchip, desired-num-phases
  mmc: renesas-sdhi: improve checkpatch cleanness
  mmc: tmio: improve checkpatch cleanness
  mmc: sdhci-pci: Enable card detect wake for Intel BYT-related SD controllers
  mmc: slot-gpio: Add support to enable irq wake on cd_irq
  mmc: core: Remove MMC_CAP2_HC_ERASE_SZ
  mmc: core: for data errors, take response of stop cmd into account
  mmc: core: check also R1 response for stop commands
  mmc: core: Clarify code for sending CSD
  mmc: core: Drop mmc_all_send_cid() and use mmc_send_cxd_native() instead
  mmc: core: Re-factor code for sending CID
  mmc: core: Remove redundant code in mmc_send_cid()
  mmc: core: Make mmc_can_reset() static
  ...
</content>
</entry>
<entry>
<title>mmc/block: remove a call to blk_queue_bounce_limit</title>
<updated>2017-06-27T18:13:45+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2017-06-19T07:26:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=8298912bb6de7e3c9f86ad19d6488ac88cd0e940'/>
<id>urn:sha1:8298912bb6de7e3c9f86ad19d6488ac88cd0e940</id>
<content type='text'>
BLK_BOUNCE_ANY is the defauly now, so the call is superflous.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
</entry>
<entry>
<title>mmc: block: remove req back pointer</title>
<updated>2017-06-20T08:30:24+00:00</updated>
<author>
<name>Linus Walleij</name>
<email>linus.walleij@linaro.org</email>
</author>
<published>2017-05-19T13:37:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=67e69d5220c904238f94bb2e6001d7c590f5a0bb'/>
<id>urn:sha1:67e69d5220c904238f94bb2e6001d7c590f5a0bb</id>
<content type='text'>
Just as we can use blk_mq_rq_from_pdu() to get the per-request
tag we can use blk_mq_rq_to_pdu() to get a request from a tag.
Introduce a static inline helper so we are on the clear what
is happening.

Suggested-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
</content>
</entry>
<entry>
<title>mmc: core: Allocate per-request data using the block layer core</title>
<updated>2017-06-20T08:30:17+00:00</updated>
<author>
<name>Linus Walleij</name>
<email>linus.walleij@linaro.org</email>
</author>
<published>2017-05-18T09:29:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=304419d8a7e9204c5d19b704467b814df8c8f5b1'/>
<id>urn:sha1:304419d8a7e9204c5d19b704467b814df8c8f5b1</id>
<content type='text'>
The mmc_queue_req is a per-request state container the MMC core uses
to carry bounce buffers, pointers to asynchronous requests and so on.
Currently allocated as a static array of objects, then as a request
comes in, a mmc_queue_req is assigned to it, and used during the
lifetime of the request.

This is backwards compared to how other block layer drivers work:
they usally let the block core provide a per-request struct that get
allocated right beind the struct request, and which can be obtained
using the blk_mq_rq_to_pdu() helper. (The _mq_ infix in this function
name is misleading: it is used by both the old and the MQ block
layer.)

The per-request struct gets allocated to the size stored in the queue
variable .cmd_size initialized using the .init_rq_fn() and
cleaned up using .exit_rq_fn().

The block layer code makes the MMC core rely on this mechanism to
allocate the per-request mmc_queue_req state container.

Doing this make a lot of complicated queue handling go away. We only
need to keep the .qnct that keeps count of how many request are
currently being processed by the MMC layer. The MQ block layer will
replace also this once we transition to it.

Doing this refactoring is necessary to move the ioctl() operations
into custom block layer requests tagged with REQ_OP_DRV_[IN|OUT]
instead of the custom code using the BigMMCHostLock that we have
today: those require that per-request data be obtainable easily from
a request after creating a custom request with e.g.:

struct request *rq = blk_get_request(q, REQ_OP_DRV_IN, __GFP_RECLAIM);
struct mmc_queue_req *mq_rq = req_to_mq_rq(rq);

And this is not possible with the current construction, as the request
is not immediately assigned the per-request state container, but
instead it gets assigned when the request finally enters the MMC
queue, which is way too late for custom requests.

Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
[Ulf: Folded in the fix to drop a call to blk_cleanup_queue()]
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
Tested-by: Heiner Kallweit &lt;hkallweit1@gmail.com&gt;
</content>
</entry>
<entry>
<title>mmc: core: Delete bounce buffer Kconfig option</title>
<updated>2017-06-20T08:30:17+00:00</updated>
<author>
<name>Linus Walleij</name>
<email>linus.walleij@linaro.org</email>
</author>
<published>2017-05-18T09:29:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=c3dccb74be28a345a2ebcc224e41b774529b8b8f'/>
<id>urn:sha1:c3dccb74be28a345a2ebcc224e41b774529b8b8f</id>
<content type='text'>
This option is activated by all multiplatform configs and what
not so we almost always have it turned on, and the memory it
saves is negligible, even more so moving forward. The actual
bounce buffer only gets allocated only when used, the only
thing the ifdefs are saving is a little bit of code.

It is highly improper to have this as a Kconfig option that
get turned on by Kconfig, make this a pure runtime-thing and
let the host decide whether we use bounce buffers. We add a
new property "disable_bounce" to the host struct.

Notice that mmc_queue_calc_bouncesz() already disables the
bounce buffers if host-&gt;max_segs != 1, so any arch that has a
maximum number of segments higher than 1 will have bounce
buffers disabled.

The option CONFIG_MMC_BLOCK_BOUNCE is default y so the
majority of platforms in the kernel already have it on, and
it then gets turned off at runtime since most of these have
a host-&gt;max_segs &gt; 1. The few exceptions that have
host-&gt;max_segs == 1 and still turn off the bounce buffering
are those that disable it in their defconfig.

Those are the following:

arch/arm/configs/colibri_pxa300_defconfig
arch/arm/configs/zeus_defconfig
- Uses MMC_PXA, drivers/mmc/host/pxamci.c
- Sets host-&gt;max_segs = NR_SG, which is 1
- This needs its bounce buffer deactivated so we set
  host-&gt;disable_bounce to true in the host driver

arch/arm/configs/davinci_all_defconfig
- Uses MMC_DAVINCI, drivers/mmc/host/davinci_mmc.c
- This driver sets host-&gt;max_segs to MAX_NR_SG, which is 16
- That means this driver anyways disabled bounce buffers
- No special action needed for this platform

arch/arm/configs/lpc32xx_defconfig
arch/arm/configs/nhk8815_defconfig
arch/arm/configs/u300_defconfig
- Uses MMC_ARMMMCI, drivers/mmc/host/mmci.[c|h]
- This driver by default sets host-&gt;max_segs to NR_SG,
  which is 128, unless a DMA engine is used, and in that case
  the number of segments are also &gt; 1
- That means this driver already disables bounce buffers
- No special action needed for these platforms

arch/arm/configs/sama5_defconfig
- Uses MMC_SDHCI, MMC_SDHCI_PLTFM, MMC_SDHCI_OF_AT91, MMC_ATMELMCI
- Uses drivers/mmc/host/sdhci.c
- Normally sets host-&gt;max_segs to SDHCI_MAX_SEGS which is 128 and
  thus disables bounce buffers
- Sets host-&gt;max_segs to 1 if SDHCI_USE_SDMA is set
- SDHCI_USE_SDMA is only set by SDHCI on PCI adapers
- That means that for this platform bounce buffers are already
  disabled at runtime
- No special action needed for this platform

arch/blackfin/configs/CM-BF533_defconfig
arch/blackfin/configs/CM-BF537E_defconfig
- Uses MMC_SPI (a simple MMC card connected on SPI pins)
- Uses drivers/mmc/host/mmc_spi.c
- Sets host-&gt;max_segs to MMC_SPI_BLOCKSATONCE which is 128
- That means this platform already disables bounce buffers at
  runtime
- No special action needed for these platforms

arch/mips/configs/cavium_octeon_defconfig
- Uses MMC_CAVIUM_OCTEON, drivers/mmc/host/cavium.c
- Sets host-&gt;max_segs to 16 or 1
- Setting host-&gt;disable_bounce to be sure for the 1 case

arch/mips/configs/qi_lb60_defconfig
- Uses MMC_JZ4740, drivers/mmc/host/jz4740_mmc.c
- This sets host-&gt;max_segs to 128 so bounce buffers are
  already runtime disabled
- No action needed for this platform

It would be interesting to come up with a list of the platforms
that actually end up using bounce buffers. I have not been
able to infer such a list, but it occurs when
host-&gt;max_segs == 1 and the bounce buffering is not explicitly
disabled.

Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
</content>
</entry>
<entry>
<title>block: introduce new block status code type</title>
<updated>2017-06-09T15:27:32+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2017-06-03T07:38:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=2a842acab109f40f0d7d10b38e9ca88390628996'/>
<id>urn:sha1:2a842acab109f40f0d7d10b38e9ca88390628996</id>
<content type='text'>
Currently we use nornal Linux errno values in the block layer, and while
we accept any error a few have overloaded magic meanings.  This patch
instead introduces a new  blk_status_t value that holds block layer specific
status codes and explicitly explains their meaning.  Helpers to convert from
and to the previous special meanings are provided for now, but I suspect
we want to get rid of them in the long run - those drivers that have a
errno input (e.g. networking) usually get errnos that don't know about
the special block layer overloads, and similarly returning them to userspace
will usually return somethings that strictly speaking isn't correct
for file system operations, but that's left as an exercise for later.

For now the set of errors is a very limited set that closely corresponds
to the previous overloaded errno values, but there is some low hanging
fruite to improve it.

blk_status_t (ab)uses the sparse __bitwise annotations to allow for sparse
typechecking, so that we can easily catch places passing the wrong values.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Jens Axboe &lt;axboe@fb.com&gt;
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