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    Subject[PATCH v9 23/69] mm: use maple tree operations for find_vma_intersection()
    Date
    From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

    Move find_vma_intersection() to mmap.c and change implementation to maple
    tree.

    When searching for a vma within a range, it is easier to use the maple
    tree interface.

    Exported find_vma_intersection() for kvm module.

    Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
    ---
    include/linux/mm.h | 22 ++++------------------
    mm/mmap.c | 29 +++++++++++++++++++++++++++++
    mm/nommu.c | 11 +++++++++++
    3 files changed, 44 insertions(+), 18 deletions(-)

    diff --git a/include/linux/mm.h b/include/linux/mm.h
    index 0fdb19d1b48b..6db9face6f84 100644
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -2780,26 +2780,12 @@ extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long add
    extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
    struct vm_area_struct **pprev);

    -/**
    - * find_vma_intersection() - Look up the first VMA which intersects the interval
    - * @mm: The process address space.
    - * @start_addr: The inclusive start user address.
    - * @end_addr: The exclusive end user address.
    - *
    - * Returns: The first VMA within the provided range, %NULL otherwise. Assumes
    - * start_addr < end_addr.
    +/*
    + * Look up the first VMA which intersects the interval [start_addr, end_addr)
    + * NULL if none. Assume start_addr < end_addr.
    */
    -static inline
    struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
    - unsigned long start_addr,
    - unsigned long end_addr)
    -{
    - struct vm_area_struct *vma = find_vma(mm, start_addr);
    -
    - if (vma && end_addr <= vma->vm_start)
    - vma = NULL;
    - return vma;
    -}
    + unsigned long start_addr, unsigned long end_addr);

    /**
    * vma_lookup() - Find a VMA at a specific address
    diff --git a/mm/mmap.c b/mm/mmap.c
    index ec4ce76f02dc..5f948f353376 100644
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -2069,6 +2069,35 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,

    EXPORT_SYMBOL(get_unmapped_area);

    +/**
    + * find_vma_intersection() - Look up the first VMA which intersects the interval
    + * @mm: The process address space.
    + * @start_addr: The inclusive start user address.
    + * @end_addr: The exclusive end user address.
    + *
    + * Returns: The first VMA within the provided range, %NULL otherwise. Assumes
    + * start_addr < end_addr.
    + */
    +struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
    + unsigned long start_addr,
    + unsigned long end_addr)
    +{
    + struct vm_area_struct *vma;
    + unsigned long index = start_addr;
    +
    + mmap_assert_locked(mm);
    + /* Check the cache first. */
    + vma = vmacache_find(mm, start_addr);
    + if (likely(vma))
    + return vma;
    +
    + vma = mt_find(&mm->mm_mt, &index, end_addr - 1);
    + if (vma)
    + vmacache_update(start_addr, vma);
    + return vma;
    +}
    +EXPORT_SYMBOL(find_vma_intersection);
    +
    /**
    * find_vma() - Find the VMA for a given address, or the next vma.
    * @mm: The mm_struct to check
    diff --git a/mm/nommu.c b/mm/nommu.c
    index 81408d20024f..2870edfad8ed 100644
    --- a/mm/nommu.c
    +++ b/mm/nommu.c
    @@ -629,6 +629,17 @@ static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
    vm_area_free(vma);
    }

    +struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
    + unsigned long start_addr,
    + unsigned long end_addr)
    +{
    + unsigned long index = start_addr;
    +
    + mmap_assert_locked(mm);
    + return mt_find(&mm->mm_mt, &index, end_addr - 1);
    +}
    +EXPORT_SYMBOL(find_vma_intersection);
    +
    /*
    * look up the first VMA in which addr resides, NULL if none
    * - should be called with mm->mmap_lock at least held readlocked
    --
    2.35.1
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