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    SubjectRe: [PATCH v6 00/11] cleanups and unit test for mballoc
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    on 8/30/2023 3:02 AM, Ritesh Harjani wrote:
    > Kemeng Shi <shikemeng@huaweicloud.com> 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
    Hi ritesh, thanks for feedback. I think the compilation problem below is
    relevant to this change which relie on fix [7]. I'm not sure if I need to
    include fix [7] in this set to fix the compilation error. Would like to
    hear any advise!

    >> 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@huaweicloud.com/T/#m5ff8e3a058ce1cb272dfef3262cd3202ce6e4358
    >> [2]
    >> https://lore.kernel.org/linux-ext4/ZC3MoWn2UO6p+Swp@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com/
    >> [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@mit.edu/
    >> [6]
    >> https://lore.kernel.org/linux-ext4/20230629120044.1261968-1-shikemeng@huaweicloud.com/T/#mcc8fb0697fd54d9267c02c027e1eb3468026ae56
    >> [7]
    >> https://lore.kernel.org/lkml/20230725172051.2142641-1-shikemeng@huaweicloud.com/
    >>
    >> 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
    >

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