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Filipe Manana a5e6ea18e3 fs: allow deduplication of eof block into the end of the destination file
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>
2020-01-23 18:20:48 +01:00
arch RISC-V updates for v5.5-rc7 2020-01-19 12:10:28 -08:00
block block: fix an integer overflow in logical block size 2020-01-15 21:43:09 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto tpmdd fixes for Linux v5.5-rc3 2019-12-18 17:17:36 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
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fs fs: allow deduplication of eof block into the end of the destination file 2020-01-23 18:20:48 +01:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
init mm, debug_pagealloc: don't rely on static keys too early 2020-01-13 18:19:02 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
lib lib/vdso: Make __cvdso_clock_getres() static 2020-01-10 19:29:01 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid 2020-01-13 18:19:02 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
samples samples/seccomp: Zero out members based on seccomp_notif_sizes 2020-01-02 13:03:39 -08:00
scripts Kbuild fixes for v5.5 (2nd) 2020-01-03 11:21:25 -08:00
security + Bug fixes 2020-01-04 19:28:30 -08:00
sound sound fixes for 5.5-rc7 2020-01-17 08:38:35 -08:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt PPC KVM fix for 5.5 2019-12-22 13:18:15 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
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COPYING
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
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 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-19 12:03:53 -08:00
Makefile Linux 5.5-rc7 2020-01-19 16:02:49 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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.

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.