linux-toradex.git/fs/ext4/fast_commit.h, branch v6.1

ext4: introduce EXT4_FC_TAG_BASE_LEN helper

2022-10-01T03:46:54+00:00

Introduce EXT4_FC_TAG_BASE_LEN helper for calculate length of
struct ext4_fc_tl.

Signed-off-by: Ye Bin 
Link: https://lore.kernel.org/r/20220924075233.2315259-2-yebin10@huawei.com
Signed-off-by: Theodore Ts'o

Merge tag 'flexible-array-transformations-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

2022-03-24T18:39:32+00:00

Pull flexible-array transformations from Gustavo Silva:
 "Treewide patch that replaces zero-length arrays with flexible-array
  members.

  This has been baking in linux-next for a whole development cycle"

* tag 'flexible-array-transformations-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux:
  treewide: Replace zero-length arrays with flexible-array members

ext4: remove unused enum EXT4_FC_COMMIT_FAILED

2022-03-13T02:26:08+00:00

Below commit removed all references of EXT4_FC_COMMIT_FAILED.
commit 0915e464cb274 ("ext4: simplify updating of fast commit stats")

Just remove it since it is not used anymore.

Signed-off-by: Ritesh Harjani 
Reviewed-by: Jan Kara 
Reviewed-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/c941357e476be07a1138c7319ca5faab7fb80fc6.1647057583.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o

ext4: improve fast_commit performance and scalability

2022-03-03T04:11:15+00:00

Currently ext4_fc_commit_dentry_updates() is of quadratic time
complexity, which is causing performance bottlenecks with high
threads/file/dir count with fs_mark.

This patch makes commit dentry updates (and hence ext4_fc_commit()) path
to linear time complexity. Hence improves the performance of workloads
which does fsync on multiple threads/open files one-by-one.

Absolute numbers in avg file creates per sec (from fs_mark in 1K order)
=======================================================================
no.     Order   without-patch(K)   with-patch(K)   Diff(%)
1       1        16.90              17.51           +3.60
2       2,2      32.08              31.80           -0.87
3       3,3      53.97              55.01           +1.92
4       4,4      78.94              76.90           -2.58
5       5,5      95.82              95.37           -0.46
6       6,6      87.92              103.38          +17.58
7       6,10      0.73              126.13          +17178.08
8       6,14      2.33              143.19          +6045.49

workload type
==============
For e.g. 7th row order of 6,10 (2^6 == 64 && 2^10 == 1024)
echo /run/riteshh/mnt/{1..64} |sed -E 's/[[:space:]]+/ -d /g' \
  | xargs -I {} bash -c "sudo fs_mark -L 100 -D 1024 -n 1024 -s0 -S5 -d {}"

Perf profile
(w/o patches)
=============================
87.15%  [kernel]  [k] ext4_fc_commit           --> Heavy contention/bottleneck
 1.98%  [kernel]  [k] perf_event_interrupt
 0.96%  [kernel]  [k] power_pmu_enable
 0.91%  [kernel]  [k] update_sd_lb_stats.constprop.0
 0.67%  [kernel]  [k] ktime_get

Signed-off-by: Ritesh Harjani 
Reviewed-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/930f35d4fd5f83e2673c868781d9ebf15e91bf4e.1645426817.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o

treewide: Replace zero-length arrays with flexible-array members

2022-02-17T13:00:39+00:00

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(next-20220214$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
  ...
  T1 member;
  T2 array[
- 0
  ];
};

UAPI and wireless changes were intentionally excluded from this patch
and will be sent out separately.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Reviewed-by: Kees Cook 
Signed-off-by: Gustavo A. R. Silva

ext4: simplify updating of fast commit stats

2021-12-23T23:13:25+00:00

Move fast commit stats updating logic to a separate function from
ext4_fc_commit(). This significantly improves readability of
ext4_fc_commit().

Signed-off-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/20211223202140.2061101-4-harshads@google.com
Signed-off-by: Theodore Ts'o

ext4: fix fast commit alignment issues

2021-06-06T14:10:23+00:00

Fast commit recovery data on disk may not be aligned. So, when the
recovery code reads it, this patch makes sure that fast commit info
found on-disk is first memcpy-ed into an aligned variable before
accessing it. As a consequence of it, we also remove some macros that
could resulted in unaligned accesses.

Cc: stable@kernel.org
Fixes: 8016e29f4362 ("ext4: fast commit recovery path")
Signed-off-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/20210519215920.2037527-1-harshads@google.com
Signed-off-by: Theodore Ts'o

ext4: make fast_commit.h byte identical with e2fsprogs/fast_commit.h

2020-12-17T18:30:45+00:00

This patch makes fast_commit.h byte by byte identical with
e2fsprogs/fast_commit.h. This will help us ensure that there are no
on-disk format inconsistencies between e2fsck and kernel ext4.

Signed-off-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/20201120202232.2240293-1-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o

ext4: disable fast commit with data journalling

2020-11-07T04:01:05+00:00

Fast commits don't work with data journalling. This patch disables the
fast commit support when data journalling is turned on.

Suggested-by: Jan Kara 
Signed-off-by: Harshad Shirwadkar 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20201106035911.1942128-19-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o

ext4: clean up the JBD2 API that initializes fast commits

2020-11-07T04:01:03+00:00

This patch removes jbd2_fc_init() API and its related functions to
simplify enabling fast commits. With this change, the number of fast
commit blocks to use is solely determined by the JBD2 layer. So, we
move the default value for minimum number of fast commit blocks from
ext4/fast_commit.h to include/linux/jbd2.h. However, whether or not to
use fast commits is determined by the file system. The file system
just sets the fast commit feature using
jbd2_journal_set_features(). JBD2 layer then determines how many
blocks to use for fast commits (based on the value found in the JBD2
superblock).

Note that the JBD2 feature flag of fast commits is just an indication
that there are fast commit blocks present on disk. It doesn't tell
JBD2 layer about the intent of the file system of whether to it wants
to use fast commit or not. That's why, we blindly clear the fast
commit flag in journal_reset() after the recovery is done.

Suggested-by: Jan Kara 
Signed-off-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/20201106035911.1942128-7-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o