[PATCH] mm: move get_vma_name() from procfs to mm tree

["qiwu.chen" <qiwuchen55@gmail.com>]

Commit acd4b2ecf3bb2 ("fs/procfs: extract logic for getting VMA name
constituents") introduces a generic helper to get VMA name constituents.
Currently, it's statically defined and referenced in fs/proc/task_mmu.c,
which is not opened to users who want to query VMA name more efficiently.

This patch moves get_vma_name() from procfs to mm/mmap.c, and export it
for modules usage.

There should be no functional changes.

Signed-off-by: qiwu.chen <qiwu.chen@transsion.com>
---
 fs/proc/task_mmu.c | 61 --------------------------------------
 include/linux/mm.h |  2 ++
 mm/mmap.c          | 74 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+), 61 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 72f14fd59c2d..7d414c39367a 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -240,67 +240,6 @@ static int do_maps_open(struct inode *inode, struct file *file,
 				sizeof(struct proc_maps_private));
 }
 
-static void get_vma_name(struct vm_area_struct *vma,
-			 const struct path **path,
-			 const char **name,
-			 const char **name_fmt)
-{
-	struct anon_vma_name *anon_name = vma->vm_mm ? anon_vma_name(vma) : NULL;
-
-	*name = NULL;
-	*path = NULL;
-	*name_fmt = NULL;
-
-	/*
-	 * Print the dentry name for named mappings, and a
-	 * special [heap] marker for the heap:
-	 */
-	if (vma->vm_file) {
-		/*
-		 * If user named this anon shared memory via
-		 * prctl(PR_SET_VMA ..., use the provided name.
-		 */
-		if (anon_name) {
-			*name_fmt = "[anon_shmem:%s]";
-			*name = anon_name->name;
-		} else {
-			*path = file_user_path(vma->vm_file);
-		}
-		return;
-	}
-
-	if (vma->vm_ops && vma->vm_ops->name) {
-		*name = vma->vm_ops->name(vma);
-		if (*name)
-			return;
-	}
-
-	*name = arch_vma_name(vma);
-	if (*name)
-		return;
-
-	if (!vma->vm_mm) {
-		*name = "[vdso]";
-		return;
-	}
-
-	if (vma_is_initial_heap(vma)) {
-		*name = "[heap]";
-		return;
-	}
-
-	if (vma_is_initial_stack(vma)) {
-		*name = "[stack]";
-		return;
-	}
-
-	if (anon_name) {
-		*name_fmt = "[anon:%s]";
-		*name = anon_name->name;
-		return;
-	}
-}
-
 static void show_vma_header_prefix(struct seq_file *m,
 				   unsigned long start, unsigned long end,
 				   vm_flags_t flags, unsigned long long pgoff,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ecf63d2b0582..31abb857e11e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3418,6 +3418,8 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address);
 extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);
 extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
 					     struct vm_area_struct **pprev);
+extern void get_vma_name(struct vm_area_struct *vma, const struct path **path,
+			const char **name, const char **name_fmt);
 
 /*
  * Look up the first VMA which intersects the interval [start_addr, end_addr)
diff --git a/mm/mmap.c b/mm/mmap.c
index ee8f91eaadb9..d6ca383fc302 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -995,6 +995,80 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
 	return vma;
 }
 
+/**
+ * get_vma_name() - get VMA name with relevant pieces of data.
+ * @vma: The vma to check
+ * @path: The file path given to the vma
+ * @name: The vma name
+ * @name_fmt: The formatted vma name
+ *
+ * Extract generic logic to fetch relevant pieces of data to describe
+ * VMA name. This could be just some string (either special constant or
+ * user-provided), or a string with some formatted wrapping text (e.g.,
+ * "[anon_shmem:<something>]"), or, commonly, file path.
+ */
+void get_vma_name(struct vm_area_struct *vma,
+			 const struct path **path,
+			 const char **name,
+			 const char **name_fmt)
+{
+	struct anon_vma_name *anon_name = vma->vm_mm ? anon_vma_name(vma) : NULL;
+
+	*name = NULL;
+	*path = NULL;
+	*name_fmt = NULL;
+
+	/*
+	 * Print the dentry name for named mappings, and a
+	 * special [heap] marker for the heap:
+	 */
+	if (vma->vm_file) {
+		/*
+		 * If user named this anon shared memory via
+		 * prctl(PR_SET_VMA ..., use the provided name.
+		 */
+		if (anon_name) {
+			*name_fmt = "[anon_shmem:%s]";
+			*name = anon_name->name;
+		} else {
+			*path = file_user_path(vma->vm_file);
+		}
+		return;
+	}
+
+	if (vma->vm_ops && vma->vm_ops->name) {
+		*name = vma->vm_ops->name(vma);
+		if (*name)
+			return;
+	}
+
+	*name = arch_vma_name(vma);
+	if (*name)
+		return;
+
+	if (!vma->vm_mm) {
+		*name = "[vdso]";
+		return;
+	}
+
+	if (vma_is_initial_heap(vma)) {
+		*name = "[heap]";
+		return;
+	}
+
+	if (vma_is_initial_stack(vma)) {
+		*name = "[stack]";
+		return;
+	}
+
+	if (anon_name) {
+		*name_fmt = "[anon:%s]";
+		*name = anon_name->name;
+		return;
+	}
+}
+EXPORT_SYMBOL(get_vma_name);
+
 /*
  * Verify that the stack growth is acceptable and
  * update accounting. This is shared with both the
-- 
2.25.1