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Evan Green 012fd9ffcd loop: Better discard support for block devices
[ Upstream commit c52abf5630 ]

If the backing device for a loop device is itself a block device,
then mirror the "write zeroes" capabilities of the underlying
block device into the loop device. Copy this capability into both
max_write_zeroes_sectors and max_discard_sectors of the loop device.

The reason for this is that REQ_OP_DISCARD on a loop device translates
into blkdev_issue_zeroout(), rather than blkdev_issue_discard(). This
presents a consistent interface for loop devices (that discarded data
is zeroed), regardless of the backing device type of the loop device.
There should be no behavior change for loop devices backed by regular
files.

This change fixes blktest block/003, and removes an extraneous
error print in block/013 when testing on a loop device backed
by a block device that does not support discard.

Signed-off-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
[used updated version of Evan's comment in loop_config_discard()]
[moved backingq to local scope, removed redundant braces]
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-04-29 16:31:13 +02:00
arch arm64: Silence clang warning on mismatched value/register sizes 2020-04-29 16:31:09 +02:00
block block, bfq: fix use-after-free in bfq_idle_slice_timer_body 2020-04-17 10:48:42 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: api - Fix race condition in crypto_spawn_alg 2020-02-11 04:34:05 -08:00
Documentation arm64: errata: Hide CTR_EL0.DIC on systems affected by Neoverse-N1 #1542419 2020-04-29 16:31:08 +02:00
drivers loop: Better discard support for block devices 2020-04-29 16:31:13 +02:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:21:29 +01:00
fs ceph: don't skip updating wanted caps when cap is stale 2020-04-29 16:31:11 +02:00
include KEYS: Don't write out to userspace while holding key semaphore 2020-04-23 10:30:24 +02:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc ipc/util.c: sysvipc_find_ipc() should increase position index 2020-04-29 16:31:13 +02:00
kernel kernel/gcov/fs.c: gcov_seq_next() should increase position index 2020-04-29 16:31:12 +02:00
lib lib/raid6: use vdupq_n_u8 to avoid endianness warnings 2020-04-23 10:30:15 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/vmalloc.c: move 'area->pages' after if statement 2020-04-21 09:03:13 +02:00
net vti4: removed duplicate log message. 2020-04-29 16:31:08 +02:00
samples samples/bpf: Don't try to remove user's homedir on clean 2020-02-11 04:34:05 -08:00
scripts kconfig: qconf: Fix a few alignment issues 2020-04-29 16:31:13 +02:00
security KEYS: Don't write out to userspace while holding key semaphore 2020-04-23 10:30:24 +02:00
sound ASoC: Intel: atom: Take the drv->lock mutex before calling sst_send_slot_map() 2020-04-29 16:31:11 +02:00
tools selftests: kmod: fix handling test numbers above 9 2020-04-29 16:31:12 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:44:59 +02:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:42:21 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:38:49 +01:00
Makefile Linux 4.19.118 2020-04-23 10:30:24 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.