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Joe Thornber a8d99d6301 dm space map common: fix to ensure new block isn't already in use
commit 4feaef830d upstream.

The space-maps track the reference counts for disk blocks allocated by
both the thin-provisioning and cache targets.  There are variants for
tracking metadata blocks and data blocks.

Transactionality is implemented by never touching blocks from the
previous transaction, so we can rollback in the event of a crash.

When allocating a new block we need to ensure the block is free (has
reference count of 0) in both the current and previous transaction.
Prior to this fix we were doing this by searching for a free block in
the previous transaction, and relying on a 'begin' counter to track
where the last allocation in the current transaction was.  This
'begin' field was not being updated in all code paths (eg, increment
of a data block reference count due to breaking sharing of a neighbour
block in the same btree leaf).

This fix keeps the 'begin' field, but now it's just a hint to speed up
the search.  Instead the current transaction is searched for a free
block, and then the old transaction is double checked to ensure it's
free.  Much simpler.

This fixes reports of sm_disk_new_block()'s BUG_ON() triggering when
DM thin-provisioning's snapshots are heavily used.

Reported-by: Eric Wheeler <dm-devel@lists.ewheeler.net>
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-11 04:35:26 -08:00
Documentation PM / devfreq: Add new name attribute for sysfs 2020-02-05 21:22:40 +00:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch ARM: dma-api: fix max_pfn off-by-one error in __dma_supported() 2020-02-11 04:35:25 -08:00
block block: fix memleak of bio integrity data 2020-01-26 10:01:09 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: api - Check spawn->alg under lock in crypto_drop_spawn 2020-02-11 04:35:22 -08:00
drivers dm space map common: fix to ensure new block isn't already in use 2020-02-11 04:35:26 -08:00
fs f2fs: fix race conditions in ->d_compare() and ->d_hash() 2020-02-11 04:35:25 -08:00
include cpufreq: Avoid creating excessively large stack frames 2020-02-11 04:35:25 -08:00
init Revert "um: Enable CONFIG_CONSTRUCTORS" 2020-02-01 09:34:53 +00:00
ipc ipc/msg.c: consolidate all xxxctl_down() functions 2020-02-11 04:35:07 -08:00
kernel padata: Remove broken queue flushing 2020-02-11 04:35:22 -08:00
lib lib/test_kasan.c: fix memory leak in kmalloc_oob_krealloc_more() 2020-02-11 04:35:14 -08:00
mm mm: move_pages: report the number of non-attempted pages 2020-02-11 04:35:13 -08:00
net netfilter: ipset: fix suspicious RCU usage in find_set_and_id 2020-02-11 04:35:07 -08:00
samples samples/bpf: Fix broken xdp_rxq_info due to map order assumptions 2020-01-26 10:00:58 +01:00
scripts scripts/find-unused-docs: Fix massive false positives 2020-02-11 04:35:23 -08:00
security tomoyo: Use atomic_t for statistics counter 2020-02-05 21:22:41 +00:00
sound ASoC: SOF: core: free trace on errors 2020-02-11 04:35:21 -08:00
tools cpupower: Revert library ABI changes from commit ae2917093f 2020-02-11 04:35:24 -08:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-09 10:20:00 +01:00
virt KVM: arm64: Only sign-extend MMIO up to register width 2020-02-11 04:35:16 -08:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: correct entries for ISDN/mISDN section 2020-02-11 04:35:06 -08:00
Makefile Linux 5.4.18 2020-02-05 21:22:53 +00:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.

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.