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Qu Wenruo 0d9c713cc3 btrfs: only write the sectors in the vertical stripe which has data stripes
commit bd8f7e6277 upstream.

If we have only 8K partial write at the beginning of a full RAID56
stripe, we will write the following contents:

                    0  8K           32K             64K
Disk 1	(data):     |XX|            |               |
Disk 2  (data):     |               |               |
Disk 3  (parity):   |XXXXXXXXXXXXXXX|XXXXXXXXXXXXXXX|

|X| means the sector will be written back to disk.

Note that, although we won't write any sectors from disk 2, but we will
write the full 64KiB of parity to disk.

This behavior is fine for now, but not for the future (especially for
RAID56J, as we waste quite some space to journal the unused parity
stripes).

So here we will also utilize the btrfs_raid_bio::dbitmap, anytime we
queue a higher level bio into an rbio, we will update rbio::dbitmap to
indicate which vertical stripes we need to writeback.

And at finish_rmw(), we also check dbitmap to see if we need to write
any sector in the vertical stripe.

So after the patch, above example will only lead to the following
writeback pattern:

                    0  8K           32K             64K
Disk 1	(data):     |XX|            |               |
Disk 2  (data):     |               |               |
Disk 3  (parity):   |XX|            |               |

Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-21 15:17:48 +02:00
Documentation xen-blkfront: Apply 'feature_persistent' parameter when connect 2022-08-17 14:24:28 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch x86/ftrace: Use alternative RET encoding 2022-08-21 15:17:48 +02:00
block block: don't allow the same type rq_qos add more than once 2022-08-17 14:24:24 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-17 14:24:28 +02:00
drivers tee: add overflow check in register_shm_helper() 2022-08-21 15:17:47 +02:00
fs btrfs: only write the sectors in the vertical stripe which has data stripes 2022-08-21 15:17:48 +02:00
include tracing/perf: Avoid -Warray-bounds warning for __rel_loc macro 2022-08-17 14:24:30 +02:00
init stack: Declare {randomize_,}kstack_offset to fix Sparse warnings 2022-08-17 14:23:10 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:23:10 +02:00
kernel tracing: Add '__rel_loc' using trace event macros 2022-08-17 14:24:26 +02:00
lib crypto: lib/blake2s - reduce stack frame usage in self test 2022-08-17 14:24:29 +02:00
mm mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region 2022-08-17 14:23:58 +02:00
net net_sched: cls_route: disallow handle of 0 2022-08-21 15:17:48 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:23:23 +02:00
scripts scripts/faddr2line: Fix vmlinux detection on arm64 2022-08-17 14:24:14 +02:00
security selinux: Add boundary check in put_entry() 2022-08-17 14:23:05 +02:00
sound ASoC: mchp-spdifrx: disable end of block interrupt on failures 2022-08-17 14:24:11 +02:00
tools tools/thermal: Fix possible path truncations 2022-08-17 14:24:15 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Don't set Accessed/Dirty bits for ZERO_PAGE 2022-08-17 14:23:44 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +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: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Input: goodix - add a goodix.h header file 2022-07-12 16:34:51 +02:00
Makefile Linux 5.15.61 2022-08-17 14:24:32 +02:00
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.