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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
CC:     Liam Howlett <liam.howlett@oracle.com>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH v2 37/44] mm/mmap: Use vma_prepare() and vma_complete() in
 vma_expand()
Thread-Topic: [PATCH v2 37/44] mm/mmap: Use vma_prepare() and vma_complete()
 in vma_expand()
Thread-Index: AQHZITonLQpgwctfXES3nm/KnMoahA==
Date:   Thu, 5 Jan 2023 19:16:03 +0000
Message-ID: <20230105191517.3099082-38-Liam.Howlett@oracle.com>
References: <20230105191517.3099082-1-Liam.Howlett@oracle.com>
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From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Use the new locking functions for vma_expand().  This reduces code
duplication.

At the same time change VM_BUG_ON() to VM_WARN_ON()

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 mm/mmap.c | 189 +++++++++++++++++++++---------------------------------
 1 file changed, 73 insertions(+), 116 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 3cf08aaee17d..9546d5811ca9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -519,122 +519,6 @@ static int vma_link(struct mm_struct *mm, struct vm_a=
rea_struct *vma)
 	return 0;
 }
=20
-/*
- * vma_expand - Expand an existing VMA
- *
- * @mas: The maple state
- * @vma: The vma to expand
- * @start: The start of the vma
- * @end: The exclusive end of the vma
- * @pgoff: The page offset of vma
- * @next: The current of next vma.
- *
- * Expand @vma to @start and @end.  Can expand off the start and end.  Wil=
l
- * expand over @next if it's different from @vma and @end =3D=3D @next->vm=
_end.
- * Checking if the @vma can expand and merge with @next needs to be handle=
d by
- * the caller.
- *
- * Returns: 0 on success
- */
-inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma=
,
-		      unsigned long start, unsigned long end, pgoff_t pgoff,
-		      struct vm_area_struct *next)
-{
-	struct mm_struct *mm =3D vma->vm_mm;
-	struct address_space *mapping =3D NULL;
-	struct rb_root_cached *root =3D NULL;
-	struct anon_vma *anon_vma =3D vma->anon_vma;
-	struct file *file =3D vma->vm_file;
-	bool remove_next =3D false;
-
-	if (next && (vma !=3D next) && (end =3D=3D next->vm_end)) {
-		remove_next =3D true;
-		if (next->anon_vma && !vma->anon_vma) {
-			int error;
-
-			anon_vma =3D next->anon_vma;
-			vma->anon_vma =3D anon_vma;
-			error =3D anon_vma_clone(vma, next);
-			if (error)
-				return error;
-		}
-	}
-
-	/* Not merging but overwriting any part of next is not handled. */
-	VM_BUG_ON(next && !remove_next && next !=3D vma && end > next->vm_start);
-	/* Only handles expanding */
-	VM_BUG_ON(vma->vm_start < start || vma->vm_end > end);
-
-	if (vma_iter_prealloc(vmi, vma))
-		goto nomem;
-
-	vma_adjust_trans_huge(vma, start, end, 0);
-
-	if (file) {
-		mapping =3D file->f_mapping;
-		root =3D &mapping->i_mmap;
-		uprobe_munmap(vma, vma->vm_start, vma->vm_end);
-		i_mmap_lock_write(mapping);
-	}
-
-	if (anon_vma) {
-		anon_vma_lock_write(anon_vma);
-		anon_vma_interval_tree_pre_update_vma(vma);
-	}
-
-	if (file) {
-		flush_dcache_mmap_lock(mapping);
-		vma_interval_tree_remove(vma, root);
-	}
-
-	/* VMA iterator points to previous, so set to start if necessary */
-	if (vma_iter_addr(vmi) !=3D start)
-		vma_iter_set(vmi, start);
-
-	vma->vm_start =3D start;
-	vma->vm_end =3D end;
-	vma->vm_pgoff =3D pgoff;
-	vma_iter_store(vmi, vma);
-
-	if (file) {
-		vma_interval_tree_insert(vma, root);
-		flush_dcache_mmap_unlock(mapping);
-	}
-
-	/* Expanding over the next vma */
-	if (remove_next && file) {
-		__remove_shared_vm_struct(next, file, mapping);
-	}
-
-	if (anon_vma) {
-		anon_vma_interval_tree_post_update_vma(vma);
-		anon_vma_unlock_write(anon_vma);
-	}
-
-	if (file) {
-		i_mmap_unlock_write(mapping);
-		uprobe_mmap(vma);
-	}
-
-	if (remove_next) {
-		if (file) {
-			uprobe_munmap(next, next->vm_start, next->vm_end);
-			fput(file);
-		}
-		if (next->anon_vma)
-			anon_vma_merge(vma, next);
-		mm->map_count--;
-		mpol_put(vma_policy(next));
-		vm_area_free(next);
-	}
-
-	validate_mm(mm);
-	return 0;
-
-nomem:
-	return -ENOMEM;
-}
-
 /*
  * vma_prepare() - Helper function for handling locking VMAs prior to alte=
ring
  * @vp: The initialized vma_prepare struct
@@ -756,6 +640,79 @@ static inline void vma_complete(struct vma_prepare *vp=
,
 		uprobe_mmap(vp->insert);
 }
=20
+/*
+ * vma_expand - Expand an existing VMA
+ *
+ * @vmi: The vma iterator
+ * @vma: The vma to expand
+ * @start: The start of the vma
+ * @end: The exclusive end of the vma
+ * @pgoff: The page offset of vma
+ * @next: The current of next vma.
+ *
+ * Expand @vma to @start and @end.  Can expand off the start and end.  Wil=
l
+ * expand over @next if it's different from @vma and @end =3D=3D @next->vm=
_end.
+ * Checking if the @vma can expand and merge with @next needs to be handle=
d by
+ * the caller.
+ *
+ * Returns: 0 on success
+ */
+inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma=
,
+		      unsigned long start, unsigned long end, pgoff_t pgoff,
+		      struct vm_area_struct *next)
+
+{
+	struct vma_prepare vp;
+
+	memset(&vp, 0, sizeof(vp));
+	vp.vma =3D vma;
+	vp.anon_vma =3D vma->anon_vma;
+	if (next && (vma !=3D next) && (end =3D=3D next->vm_end)) {
+		vp.remove =3D next;
+		if (next->anon_vma && !vma->anon_vma) {
+			int error;
+
+			vp.anon_vma =3D next->anon_vma;
+			vma->anon_vma =3D next->anon_vma;
+			error =3D anon_vma_clone(vma, next);
+			if (error)
+				return error;
+		}
+	}
+
+	/* Not merging but overwriting any part of next is not handled. */
+	VM_WARN_ON(next && !vp.remove &&
+		  next !=3D vma && end > next->vm_start);
+	/* Only handles expanding */
+	VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);
+
+	if (vma_iter_prealloc(vmi, vma))
+		goto nomem;
+
+	vma_adjust_trans_huge(vma, start, end, 0);
+
+	vp.file =3D vma->vm_file;
+	if (vp.file)
+		vp.mapping =3D vp.file->f_mapping;
+
+	/* VMA iterator points to previous, so set to start if necessary */
+	if (vma_iter_addr(vmi) !=3D start)
+		vma_iter_set(vmi, start);
+
+	vma_prepare(&vp);
+	vma->vm_start =3D start;
+	vma->vm_end =3D end;
+	vma->vm_pgoff =3D pgoff;
+	/* Note: mas must be pointing to the expanding VMA */
+	vma_iter_store(vmi, vma);
+
+	vma_complete(&vp, vmi, vma->vm_mm);
+	validate_mm(vma->vm_mm);
+	return 0;
+
+nomem:
+	return -ENOMEM;
+}
 /*
  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
  * is already present in an i_mmap tree without adjusting the tree.
--=20
2.35.1