mm/mmap: convert brk to use vma iterator

Use the vma iterator API for the brk() system call.  This will provide
type safety at compile time.

Link: https://lkml.kernel.org/r/20230120162650.984577-9-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index db70f3e2181e16786002fee5bb268d11610d10ab..94a477a551094d21ad39e2ce7b36f17c430a9068 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -180,10 +180,10 @@ static int check_brk_limits(unsigned long addr, unsigned long len)
 
        return mlock_future_check(current->mm, current->mm->def_flags, len);
 }
-static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
                         unsigned long newbrk, unsigned long oldbrk,
                         struct list_head *uf);
-static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *brkvma,
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
                unsigned long addr, unsigned long request, unsigned long flags);
 SYSCALL_DEFINE1(brk, unsigned long, brk)
 {
@@ -194,7 +194,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
        bool populate;
        bool downgraded = false;
        LIST_HEAD(uf);
-       MA_STATE(mas, &mm->mm_mt, 0, 0);
+       struct vma_iterator vmi;
 
        if (mmap_write_lock_killable(mm))
                return -EINTR;
@@ -242,8 +242,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
                int ret;
 
                /* Search one past newbrk */
-               mas_set(&mas, newbrk);
-               brkvma = mas_find(&mas, oldbrk);
+               vma_iter_init(&vmi, mm, newbrk);
+               brkvma = vma_find(&vmi, oldbrk);
                if (!brkvma || brkvma->vm_start >= oldbrk)
                        goto out; /* mapping intersects with an existing non-brk vma. */
                /*
@@ -252,7 +252,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
                 * before calling do_brk_munmap().
                 */
                mm->brk = brk;
-               ret = do_brk_munmap(&mas, brkvma, newbrk, oldbrk, &uf);
+               ret = do_brk_munmap(&vmi, brkvma, newbrk, oldbrk, &uf);
                if (ret == 1)  {
                        downgraded = true;
                        goto success;
@@ -270,14 +270,14 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
         * Only check if the next VMA is within the stack_guard_gap of the
         * expansion area
         */
-       mas_set(&mas, oldbrk);
-       next = mas_find(&mas, newbrk - 1 + PAGE_SIZE + stack_guard_gap);
+       vma_iter_init(&vmi, mm, oldbrk);
+       next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
        if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
                goto out;
 
-       brkvma = mas_prev(&mas, mm->start_brk);
+       brkvma = vma_prev_limit(&vmi, mm->start_brk);
        /* Ok, looks good - let it rip. */
-       if (do_brk_flags(&mas, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
+       if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
                goto out;
 
        mm->brk = brk;
@@ -2917,8 +2917,8 @@ out:
 }
 
 /*
- * brk_munmap() - Unmap a partial vma.
- * @mas: The maple tree state.
+ * brk_munmap() - Unmap a full or partial vma.
+ * @vmi: The vma iterator
  * @vma: The vma to be modified
  * @newbrk: the start of the address to unmap
  * @oldbrk: The end of the address to unmap
@@ -2928,7 +2928,7 @@ out:
  * unmaps a partial VMA mapping.  Does not handle alignment, downgrades lock if
  * possible.
  */
-static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
                         unsigned long newbrk, unsigned long oldbrk,
                         struct list_head *uf)
 {
@@ -2936,14 +2936,14 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
        int ret;
 
        arch_unmap(mm, newbrk, oldbrk);
-       ret = do_mas_align_munmap(mas, vma, mm, newbrk, oldbrk, uf, true);
+       ret = do_mas_align_munmap(&vmi->mas, vma, mm, newbrk, oldbrk, uf, true);
        validate_mm_mt(mm);
        return ret;
 }
 
 /*
  * do_brk_flags() - Increase the brk vma if the flags match.
- * @mas: The maple tree state.
+ * @vmi: The vma iterator
  * @addr: The start address
  * @len: The length of the increase
  * @vma: The vma,
@@ -2953,7 +2953,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
  * do not match then create a new anonymous VMA.  Eventually we may be able to
  * do some brk-specific accounting here.
  */
-static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
+static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
                unsigned long addr, unsigned long len, unsigned long flags)
 {
        struct mm_struct *mm = current->mm;
@@ -2980,8 +2980,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
        if (vma && vma->vm_end == addr && !vma_policy(vma) &&
            can_vma_merge_after(vma, flags, NULL, NULL,
                                addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
-               mas_set_range(mas, vma->vm_start, addr + len - 1);
-               if (mas_preallocate(mas, GFP_KERNEL))
+               if (vma_iter_prealloc(vmi))
                        goto unacct_fail;
 
                vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
@@ -2991,7 +2990,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
                }
                vma->vm_end = addr + len;
                vma->vm_flags |= VM_SOFTDIRTY;
-               mas_store_prealloc(mas, vma);
+               vma_iter_store(vmi, vma);
 
                if (vma->anon_vma) {
                        anon_vma_interval_tree_post_update_vma(vma);
@@ -3012,8 +3011,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
        vma->vm_pgoff = addr >> PAGE_SHIFT;
        vma->vm_flags = flags;
        vma->vm_page_prot = vm_get_page_prot(flags);
-       mas_set_range(mas, vma->vm_start, addr + len - 1);
-       if (mas_store_gfp(mas, vma, GFP_KERNEL))
+       if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
                goto mas_store_fail;
 
        mm->map_count++;
@@ -3042,7 +3040,7 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
        int ret;
        bool populate;
        LIST_HEAD(uf);
-       MA_STATE(mas, &mm->mm_mt, addr, addr);
+       VMA_ITERATOR(vmi, mm, addr);
 
        len = PAGE_ALIGN(request);
        if (len < request)
@@ -3061,12 +3059,12 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
        if (ret)
                goto limits_failed;
 
-       ret = do_mas_munmap(&mas, mm, addr, len, &uf, 0);
+       ret = do_mas_munmap(&vmi.mas, mm, addr, len, &uf, 0);
        if (ret)
                goto munmap_failed;
 
-       vma = mas_prev(&mas, 0);
-       ret = do_brk_flags(&mas, vma, addr, len, flags);
+       vma = vma_prev(&vmi);
+       ret = do_brk_flags(&vmi, vma, addr, len, flags);
        populate = ((mm->def_flags & VM_LOCKED) != 0);
        mmap_write_unlock(mm);
        userfaultfd_unmap_complete(mm, &uf);