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    SubjectRe: [PATCH 13/21] ext4: remove dead check in mb_buddy_mark_free
    On Fri, Feb 10, 2023 at 03:48:17AM +0800, Kemeng Shi wrote:
    > We always adjust first to even number and adjust last to odd number, so
    > first == last will never happen. Remove this dead check.
    >
    > Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
    > ---
    > fs/ext4/mballoc.c | 3 ++-
    > 1 file changed, 2 insertions(+), 1 deletion(-)
    >
    > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
    > index bdabe0d81d4a..0fdbf16ac180 100644
    > --- a/fs/ext4/mballoc.c
    > +++ b/fs/ext4/mballoc.c
    > @@ -1718,7 +1718,8 @@ static void mb_buddy_mark_free(struct ext4_buddy *e4b, int first, int last)
    > break;
    > order++;
    >
    > - if (first == last || !(buddy2 = mb_find_buddy(e4b, order, &max))) {
    > + buddy2 = mb_find_buddy(e4b, order, &max);
    > + if (!buddy2) {
    > mb_clear_bits(buddy, first, last - first + 1);
    > e4b->bd_info->bb_counters[order - 1] += last - first + 1;
    > break;
    > --
    > 2.30.0
    >
    Okay, so I checked the code and seems like you are right. There is can't be any
    scenario where (first == last) after the calls to mb_buddy_adjust_border().

    However, I'm a bit hesitant to give my Reviewed by since buddy algo is still a
    bit confusing to me and I might be missing some weird edge case. Maybe someone
    can help double check this.

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