Re: [PATCH v6 00/11] cleanups and unit test for mballoc
From: IBM
Date: Tue Aug 29 2023 - 15:03:52 EST
Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> writes:
> v5-v6:
>
Hi Kemeng,
Sorry for the delay in getting started on this. I am going through the
series now.
> 1. Separate block bitmap and buddy bitmap freeing in individual patch
> and rewrite the descriptions.
> 2. Remove #ifdef around KUNIT_STATIC_STUB_REDIRECT which should be
> only defined when CONFIG_KUNIT is enabled after fix [7] which was merged
> into kunit-next/kunit
> 3. Use mbt prefix to distiguish test APIs from actual kernel APIs.
> 4. Add prepare function for ext4_mark_context and rename
> ext4_mb_mark_group_bb to ext4_mb_mark_context
> 5. Support to run mballoc test with different layouts setting and
> different block size is tested.
>
> v4->v5:
> 1. WARN on free blocks to uninitialized group is removed as normal
> fast commit route may triggers this, see [1] for details. The review
> tag from Ojaswin of changed patch is also removed and a futher review
> is needed.
>
> v3->v4:
> 1. Collect Reviewed-by from Ojaswin
> 2. Do improve as Ojaswin kindly suggested: Fix typo in commit,
> WARN if try to clear bit of uninitialized group and improve
> refactoring of AGGRESSIVE_CHECK code.
> 3. Fix conflic on patch 16
> 4. Improve git log in patch 16,17
>
> v2->v3:
> 1. Fix build warnings on "ext4: add some kunit stub for mballoc kunit
> test" and "ext4: add first unit test for ext4_mb_new_blocks_simple in
> mballoc"
>
> This series is a new version of unmerged patches from [1]. The first 6
> patches of this series factor out codes to mark blocks used or freed
> which will update on disk block bitmap and group descriptor. Several
> reasons to do this:
> 1. pair behavior of alloc/free bits. For example,
> ext4_mb_new_blocks_simple will update free_clusters in struct flex_groups
> in ext4_mb_mark_bb while ext4_free_blocks_simple forgets this.
> 2. remove repeat code to read from disk, update and write back to disk.
> 3. reduce future unit test mocks to avoid real IO to update structure
> on disk.
>
> The last 2 patches add a unit test for mballoc. Before more unit tests
> are added, there are something should be discussed:
> 1. How to test static function in mballoc.c
> Currently, include mballoc-test.c in mballoc.c to test static function
> in mballoc.c from mballoc-test.c which is one way suggested in [2].
> Not sure if there is any more elegant way to test static function without
> touch mballoc.c.
> 2. How to add mocks to function in mballoc.c which may issue IO to disk
> Currently, KUNIT_STATIC_STUB_REDIRECT is added to functions as suggested
> in kunit document [3].
I will get back to this, after reviwing some of the initial few
refactoring patches.
But FYI - I noticed some compilation errors, when building w/o
CONFIG_KUNIT.
../fs/ext4/balloc.c: In function ‘ext4_get_group_desc’:
../fs/ext4/balloc.c:278:2: error: implicit declaration of function ‘KUNIT_STATIC_STUB_REDIRECT’ [-Werror=implicit-function-declaration]
278 | KUNIT_STATIC_STUB_REDIRECT(ext4_get_group_desc,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
-ritesh
> 3. How to simulate a block bitmap.
> Currently, a fake buffer_head with bitmap data is returned, then no
> futher change is needed.
> If we simulate a block bitmap with an array of data structure like:
> struct test_bitmap {
> unsigned int start;
> unsigned int len;
> }
> which is suggested by Theodore in [4], then we need to add mocks to
> function which expected bitmap from bitmap_bh->b_data, like
> mb_find_next_bit, mb_find_next_zero_bit and maybe more.
>
> Would like to hear any suggestion! Thanks!
>
> I run kvm-xfstest with config "ext4/all" and "-g auto" together with
> patchset for resize, you can see detail report in [6].
>
> Unit test result is as followings:
> # ./tools/testing/kunit/kunit.py run --kunitconfig=fs/ext4/.kunitconfig --raw_output
> [18:23:36] Configuring KUnit Kernel ...
> [18:23:36] Building KUnit Kernel ...
> Populating config with:
> $ make ARCH=um O=.kunit olddefconfig
> Building with:
> $ make ARCH=um O=.kunit --jobs=88
> [18:23:40] Starting KUnit Kernel (1/1)...
> KTAP version 1
> 1..2
> KTAP version 1
> # Subtest: ext4_mballoc_test
> 1..1
> KTAP version 1
> # Subtest: test_new_blocks_simple
> ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
> ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
> ok 3 block_bits=18 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
> # test_new_blocks_simple: pass:3 fail:0 skip:0 total:3
> ok 1 test_new_blocks_simple
> # Totals: pass:3 fail:0 skip:0 total:3
> ok 1 ext4_mballoc_test
> KTAP version 1
> # Subtest: ext4_inode_test
> 1..1
> KTAP version 1
> # Subtest: inode_test_xtimestamp_decoding
> ok 1 1901-12-13 Lower bound of 32bit < 0 timestamp, no extra bits
> ok 2 1969-12-31 Upper bound of 32bit < 0 timestamp, no extra bits
> ok 3 1970-01-01 Lower bound of 32bit >=0 timestamp, no extra bits
> ok 4 2038-01-19 Upper bound of 32bit >=0 timestamp, no extra bits
> ok 5 2038-01-19 Lower bound of 32bit <0 timestamp, lo extra sec bit on
> ok 6 2106-02-07 Upper bound of 32bit <0 timestamp, lo extra sec bit on
> ok 7 2106-02-07 Lower bound of 32bit >=0 timestamp, lo extra sec bit on
> ok 8 2174-02-25 Upper bound of 32bit >=0 timestamp, lo extra sec bit on
> ok 9 2174-02-25 Lower bound of 32bit <0 timestamp, hi extra sec bit on
> ok 10 2242-03-16 Upper bound of 32bit <0 timestamp, hi extra sec bit on
> ok 11 2242-03-16 Lower bound of 32bit >=0 timestamp, hi extra sec bit on
> ok 12 2310-04-04 Upper bound of 32bit >=0 timestamp, hi extra sec bit on
> ok 13 2310-04-04 Upper bound of 32bit>=0 timestamp, hi extra sec bit 1. 1 ns
> ok 14 2378-04-22 Lower bound of 32bit>= timestamp. Extra sec bits 1. Max ns
> ok 15 2378-04-22 Lower bound of 32bit >=0 timestamp. All extra sec bits on
> ok 16 2446-05-10 Upper bound of 32bit >=0 timestamp. All extra sec bits on
> # inode_test_xtimestamp_decoding: pass:16 fail:0 skip:0 total:16
> ok 1 inode_test_xtimestamp_decoding
> # Totals: pass:16 fail:0 skip:0 total:16
> ok 2 ext4_inode_test
> [18:23:41] Elapsed time: 4.960s total, 0.001s configuring, 4.842s building, 0.072s running
>
> [1]
> https://lore.kernel.org/linux-ext4/20230603150327.3596033-1-shikemeng@xxxxxxxxxxxxxxx/T/#m5ff8e3a058ce1cb272dfef3262cd3202ce6e4358
> [2]
> https://lore.kernel.org/linux-ext4/ZC3MoWn2UO6p+Swp@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> [3]
> https://docs.kernel.org/dev-tools/kunit/usage.html#testing-static-functions
> [4]
> https://docs.kernel.org/dev-tools/kunit/api/functionredirection.html#c.KUNIT_STATIC_STUB_REDIRECT
> [5]
> https://lore.kernel.org/linux-ext4/20230317155047.GB3270589@xxxxxxx/
> [6]
> https://lore.kernel.org/linux-ext4/20230629120044.1261968-1-shikemeng@xxxxxxxxxxxxxxx/T/#mcc8fb0697fd54d9267c02c027e1eb3468026ae56
> [7]
> https://lore.kernel.org/lkml/20230725172051.2142641-1-shikemeng@xxxxxxxxxxxxxxx/
>
> Kemeng Shi (11):
> ext4: factor out codes to update block bitmap and group descriptor on
> disk from ext4_mb_mark_bb
> ext4: call ext4_mb_mark_context in ext4_free_blocks_simple
> ext4: extent ext4_mb_mark_context to support allocation under journal
> ext4: call ext4_mb_mark_context in ext4_mb_mark_diskspace_used
> ext4: Separate block bitmap and buddy bitmap freeing in
> ext4_mb_clear_bb()
> ext4: call ext4_mb_mark_context in ext4_mb_clear_bb
> ext4: Separate block bitmap and buddy bitmap freeing in
> ext4_group_add_blocks()
> ext4: call ext4_mb_mark_context in ext4_group_add_blocks()
> ext4: add some kunit stub for mballoc kunit test
> ext4: add first unit test for ext4_mb_new_blocks_simple in mballoc
> ext4: run mballoc test with different layouts setting
>
> fs/ext4/balloc.c | 10 +
> fs/ext4/mballoc-test.c | 351 ++++++++++++++++++++++++++++
> fs/ext4/mballoc.c | 505 ++++++++++++++++-------------------------
> 3 files changed, 557 insertions(+), 309 deletions(-)
> create mode 100644 fs/ext4/mballoc-test.c
>
> --
> 2.30.0