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Filipe Manana a421f51377 fs: allow deduplication of eof block into the end of the destination file
commit a5e6ea18e3 upstream.

We always round down, to a multiple of the filesystem's block size, the
length to deduplicate at generic_remap_check_len().  However this is only
needed if an attempt to deduplicate the last block into the middle of the
destination file is requested, since that leads into a corruption if the
length of the source file is not block size aligned.  When an attempt to
deduplicate the last block into the end of the destination file is
requested, we should allow it because it is safe to do it - there's no
stale data exposure and we are prepared to compare the data ranges for
a length not aligned to the block (or page) size - in fact we even do
the data compare before adjusting the deduplication length.

After btrfs was updated to use the generic helpers from VFS (by commit
34a28e3d77 ("Btrfs: use generic_remap_file_range_prep() for cloning
and deduplication")) we started to have user reports of deduplication
not reflinking the last block anymore, and whence users getting lower
deduplication scores.  The main use case is deduplication of entire
files that have a size not aligned to the block size of the filesystem.

We already allow cloning the last block to the end (and beyond) of the
destination file, so allow for deduplication as well.

Link: https://lore.kernel.org/linux-btrfs/2019-1576167349.500456@svIo.N5dq.dFFD/
CC: stable@vger.kernel.org # 5.1+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-11 04:35:23 -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 powerpc/32s: Fix CPU wake-up from sleep mode 2020-02-11 04:35:18 -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 crypto: ccree - fix PM race condition 2020-02-11 04:35:22 -08:00
fs fs: allow deduplication of eof block into the end of the destination file 2020-02-11 04:35:23 -08:00
include ALSA: hda: Apply aligned MMIO access only conditionally 2020-02-11 04:35:15 -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 ARM: 8950/1: ftrace/recordmcount: filter relocation types 2020-01-29 16:45:27 +01:00
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 objtool: Silence build output 2020-02-11 04:35:10 -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.