Commit Graph

13 Commits

Author SHA1 Message Date
Linus Torvalds
3ce62cf4dc flexible-array transformations for 5.18-rc1
Hi Linus,
 
 Please, pull the following treewide patch that replaces zero-length arrays with
 flexible-array members. This patch has been baking in linux-next for a
 whole development cycle.
 
 Thanks
 --
 Gustavo
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Merge tag 'flexible-array-transformations-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

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
2022-03-24 11:39:32 -07:00
Ritesh Harjani
c864ccd182 ext4: remove unused enum EXT4_FC_COMMIT_FAILED
Below commit removed all references of EXT4_FC_COMMIT_FAILED.
commit 0915e464cb ("ext4: simplify updating of fast commit stats")

Just remove it since it is not used anymore.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/c941357e476be07a1138c7319ca5faab7fb80fc6.1647057583.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2022-03-12 21:26:08 -05:00
Ritesh Harjani
b3998b3bc6 ext4: improve fast_commit performance and scalability
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 <riteshh@linux.ibm.com>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/930f35d4fd5f83e2673c868781d9ebf15e91bf4e.1645426817.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2022-03-02 23:11:15 -05:00
Gustavo A. R. Silva
5224f79096 treewide: Replace zero-length arrays with flexible-array members
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 <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2022-02-17 07:00:39 -06:00
Harshad Shirwadkar
0915e464cb ext4: simplify updating of fast commit stats
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 <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20211223202140.2061101-4-harshads@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-12-23 18:13:25 -05:00
Harshad Shirwadkar
a7ba36bc94 ext4: fix fast commit alignment issues
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: 8016e29f43 ("ext4: fast commit recovery path")
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20210519215920.2037527-1-harshads@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-06-06 10:10:23 -04:00
Harshad Shirwadkar
941ba122ca ext4: make fast_commit.h byte identical with e2fsprogs/fast_commit.h
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 <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201120202232.2240293-1-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-12-17 13:30:45 -05:00
Harshad Shirwadkar
556e0319fb ext4: disable fast commit with data journalling
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 <jack@suse.cz>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20201106035911.1942128-19-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-11-06 23:01:05 -05:00
Harshad Shirwadkar
a1e5e465b3 ext4: clean up the JBD2 API that initializes fast commits
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 <jack@suse.cz>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201106035911.1942128-7-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-11-06 23:01:03 -05:00
Harshad Shirwadkar
b21ebf143a ext4: mark fc ineligible if inode gets evictied due to mem pressure
If inode gets evicted due to memory pressure, we have to remove it
from the fast commit list. However, that inode may have uncommitted
changes that fast commits will lose. So, just fall back to full
commits in this case. Also, rename the fast commit ineligiblity reason
from "EXT4_FC_REASON_MEM" to "EXT4_FC_REASON_MEM_NOMEM" for better
expression.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201106035911.1942128-3-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-11-06 23:01:02 -05:00
Harshad Shirwadkar
8016e29f43 ext4: fast commit recovery path
This patch adds fast commit recovery path support for Ext4 file
system. We add several helper functions that are similar in spirit to
e2fsprogs journal recovery path handlers. Example of such functions
include - a simple block allocator, idempotent block bitmap update
function etc. Using these routines and the fast commit log in the fast
commit area, the recovery path (ext4_fc_replay()) performs fast commit
log recovery.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201015203802.3597742-8-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-10-21 23:22:38 -04:00
Harshad Shirwadkar
aa75f4d3da ext4: main fast-commit commit path
This patch adds main fast commit commit path handlers. The overall
patch can be divided into two inter-related parts:

(A) Metadata updates tracking

    This part consists of helper functions to track changes that need
    to be committed during a commit operation. These updates are
    maintained by Ext4 in different in-memory queues. Following are
    the APIs and their short description that are implemented in this
    patch:

    - ext4_fc_track_link/unlink/creat() - Track unlink. link and creat
      operations
    - ext4_fc_track_range() - Track changed logical block offsets
      inodes
    - ext4_fc_track_inode() - Track inodes
    - ext4_fc_mark_ineligible() - Mark file system fast commit
      ineligible()
    - ext4_fc_start_update() / ext4_fc_stop_update() /
      ext4_fc_start_ineligible() / ext4_fc_stop_ineligible() These
      functions are useful for co-ordinating inode updates with
      commits.

(B) Main commit Path

    This part consists of functions to convert updates tracked in
    in-memory data structures into on-disk commits. Function
    ext4_fc_commit() is the main entry point to commit path.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201015203802.3597742-6-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-10-21 23:22:37 -04:00
Harshad Shirwadkar
6866d7b3f2 ext4 / jbd2: add fast commit initialization
This patch adds fast commit area trackers in the journal_t
structure. These are initialized via the jbd2_fc_init() routine that
this patch adds. This patch also adds ext4/fast_commit.c and
ext4/fast_commit.h files for fast commit code that will be added in
subsequent patches in this series.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201015203802.3597742-4-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-10-21 23:22:26 -04:00