aufs4.1 mmap patch

diff --git a/fs/buffer.c b/fs/buffer.c
index c7a5602..8c50a22 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2450,7 +2450,7 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
 	 * Update file times before taking page lock. We may end up failing the
 	 * fault so this update may be superfluous but who really cares...
 	 */
-	file_update_time(vma->vm_file);
+	vma_file_update_time(vma);
 
 	ret = __block_page_mkwrite(vma, vmf, get_block);
 	sb_end_pagefault(sb);
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 093ca14..fc1ac03 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1744,7 +1744,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path)
 	down_read(&mm->mmap_sem);
 	vma = find_exact_vma(mm, vm_start, vm_end);
 	if (vma && vma->vm_file) {
-		*path = vma->vm_file->f_path;
+		*path = vma_pr_or_file(vma)->f_path;
 		path_get(path);
 		rc = 0;
 	}
diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
index d4a3574..1397181 100644
--- a/fs/proc/nommu.c
+++ b/fs/proc/nommu.c
@@ -45,7 +45,10 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 	file = region->vm_file;
 
 	if (file) {
-		struct inode *inode = file_inode(region->vm_file);
+		struct inode *inode;
+
+		file = vmr_pr_or_file(region);
+		inode = file_inode(file);
 		dev = inode->i_sb->s_dev;
 		ino = inode->i_ino;
 	}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 6dee68d..9afa35d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -279,7 +279,10 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 	const char *name = NULL;
 
 	if (file) {
-		struct inode *inode = file_inode(vma->vm_file);
+		struct inode *inode;
+
+		file = vma_pr_or_file(vma);
+		inode = file_inode(file);
 		dev = inode->i_sb->s_dev;
 		ino = inode->i_ino;
 		pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
@@ -1479,7 +1482,7 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid)
 	struct proc_maps_private *proc_priv = &numa_priv->proc_maps;
 	struct vm_area_struct *vma = v;
 	struct numa_maps *md = &numa_priv->md;
-	struct file *file = vma->vm_file;
+	struct file *file = vma_pr_or_file(vma);
 	struct mm_struct *mm = vma->vm_mm;
 	struct mm_walk walk = {
 		.hugetlb_entry = gather_hugetlb_stats,
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 599ec2e..1740207 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -160,7 +160,10 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 	file = vma->vm_file;
 
 	if (file) {
-		struct inode *inode = file_inode(vma->vm_file);
+		struct inode *inode;
+
+		file = vma_pr_or_file(vma);
+		inode = file_inode(file);
 		dev = inode->i_sb->s_dev;
 		ino = inode->i_ino;
 		pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0755b9f..2ee5500 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1172,6 +1172,28 @@ static inline int fixup_user_fault(struct task_struct *tsk,
 }
 #endif
 
+extern void vma_do_file_update_time(struct vm_area_struct *, const char[], int);
+extern struct file *vma_do_pr_or_file(struct vm_area_struct *, const char[],
+				      int);
+extern void vma_do_get_file(struct vm_area_struct *, const char[], int);
+extern void vma_do_fput(struct vm_area_struct *, const char[], int);
+
+#define vma_file_update_time(vma)	vma_do_file_update_time(vma, __func__, \
+								__LINE__)
+#define vma_pr_or_file(vma)		vma_do_pr_or_file(vma, __func__, \
+							  __LINE__)
+#define vma_get_file(vma)		vma_do_get_file(vma, __func__, __LINE__)
+#define vma_fput(vma)			vma_do_fput(vma, __func__, __LINE__)
+
+#ifndef CONFIG_MMU
+extern struct file *vmr_do_pr_or_file(struct vm_region *, const char[], int);
+extern void vmr_do_fput(struct vm_region *, const char[], int);
+
+#define vmr_pr_or_file(region)		vmr_do_pr_or_file(region, __func__, \
+							  __LINE__)
+#define vmr_fput(region)		vmr_do_fput(region, __func__, __LINE__)
+#endif /* !CONFIG_MMU */
+
 extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
 extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
 		void *buf, int len, int write);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8d37e26..ce89d4c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -241,6 +241,7 @@ struct vm_region {
 	unsigned long	vm_top;		/* region allocated to here */
 	unsigned long	vm_pgoff;	/* the offset in vm_file corresponding to vm_start */
 	struct file	*vm_file;	/* the backing file or NULL */
+	struct file	*vm_prfile;	/* the virtual backing file or NULL */
 
 	int		vm_usage;	/* region usage count (access under nommu_region_sem) */
 	bool		vm_icache_flushed : 1; /* true if the icache has been flushed for
@@ -305,6 +306,7 @@ struct vm_area_struct {
 	unsigned long vm_pgoff;		/* Offset (within vm_file) in PAGE_SIZE
 					   units, *not* PAGE_CACHE_SIZE */
 	struct file * vm_file;		/* File we map to (can be NULL). */
+	struct file *vm_prfile;		/* shadow of vm_file */
 	void * vm_private_data;		/* was vm_pte (shared mem) */
 
 #ifndef CONFIG_MMU
diff --git a/kernel/fork.c b/kernel/fork.c
index 03c1eaa..7e215ba 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -456,7 +456,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 			struct inode *inode = file_inode(file);
 			struct address_space *mapping = file->f_mapping;
 
-			get_file(file);
+			vma_get_file(tmp);
 			if (tmp->vm_flags & VM_DENYWRITE)
 				atomic_dec(&inode->i_writecount);
 			i_mmap_lock_write(mapping);
diff --git a/mm/Makefile b/mm/Makefile
index 98c4eae..3f0c9b9 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -21,7 +21,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o \
 			   mm_init.o mmu_context.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   debug.o $(mmu-y)
+			   prfile.o debug.o $(mmu-y)
 
 obj-y += init-mm.o
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 6bf5e42..a863d0f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2062,7 +2062,7 @@ int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 	int ret = VM_FAULT_LOCKED;
 
 	sb_start_pagefault(inode->i_sb);
-	file_update_time(vma->vm_file);
+	vma_file_update_time(vma);
 	lock_page(page);
 	if (page->mapping != inode->i_mapping) {
 		unlock_page(page);
diff --git a/mm/memory.c b/mm/memory.c
index 22e037e..62096a2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2034,7 +2034,7 @@ static inline int wp_page_reuse(struct mm_struct *mm,
 		}
 
 		if (!page_mkwrite)
-			file_update_time(vma->vm_file);
+			vma_file_update_time(vma);
 	}
 
 	return VM_FAULT_WRITE;
diff --git a/mm/mmap.c b/mm/mmap.c
index bb50cac..9019a83 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -274,7 +274,7 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 	if (vma->vm_ops && vma->vm_ops->close)
 		vma->vm_ops->close(vma);
 	if (vma->vm_file)
-		fput(vma->vm_file);
+		vma_fput(vma);
 	mpol_put(vma_policy(vma));
 	kmem_cache_free(vm_area_cachep, vma);
 	return next;
@@ -886,7 +886,7 @@ again:			remove_next = 1 + (end > next->vm_end);
 	if (remove_next) {
 		if (file) {
 			uprobe_munmap(next, next->vm_start, next->vm_end);
-			fput(file);
+			vma_fput(vma);
 		}
 		if (next->anon_vma)
 			anon_vma_merge(vma, next);
@@ -1671,8 +1671,8 @@ out:
 	return addr;
 
 unmap_and_free_vma:
+	vma_fput(vma);
 	vma->vm_file = NULL;
-	fput(file);
 
 	/* Undo any partial mapping done by a device driver. */
 	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
@@ -2473,7 +2473,7 @@ static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
 		goto out_free_mpol;
 
 	if (new->vm_file)
-		get_file(new->vm_file);
+		vma_get_file(new);
 
 	if (new->vm_ops && new->vm_ops->open)
 		new->vm_ops->open(new);
@@ -2492,7 +2492,7 @@ static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
 	if (new->vm_ops && new->vm_ops->close)
 		new->vm_ops->close(new);
 	if (new->vm_file)
-		fput(new->vm_file);
+		vma_fput(new);
 	unlink_anon_vmas(new);
  out_free_mpol:
 	mpol_put(vma_policy(new));
@@ -2635,7 +2635,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 	struct vm_area_struct *vma;
 	unsigned long populate = 0;
 	unsigned long ret = -EINVAL;
-	struct file *file;
+	struct file *file, *prfile;
 
 	pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
 			"See Documentation/vm/remap_file_pages.txt.\n",
@@ -2679,10 +2679,27 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 		munlock_vma_pages_range(vma, start, start + size);
 	}
 
-	file = get_file(vma->vm_file);
+	vma_get_file(vma);
+	file = vma->vm_file;
+	prfile = vma->vm_prfile;
 	ret = do_mmap_pgoff(vma->vm_file, start, size,
 			prot, flags, pgoff, &populate);
+	if (!IS_ERR_VALUE(ret) && file && prfile) {
+		struct vm_area_struct *new_vma;
+
+		new_vma = find_vma(mm, ret);
+		if (!new_vma->vm_prfile)
+			new_vma->vm_prfile = prfile;
+		if (new_vma != vma)
+			get_file(prfile);
+	}
+	/*
+	 * two fput()s instead of vma_fput(vma),
+	 * coz vma may not be available anymore.
+	 */
 	fput(file);
+	if (prfile)
+		fput(prfile);
 out:
 	up_write(&mm->mmap_sem);
 	if (populate)
@@ -2949,7 +2966,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 			if (anon_vma_clone(new_vma, vma))
 				goto out_free_mempol;
 			if (new_vma->vm_file)
-				get_file(new_vma->vm_file);
+				vma_get_file(new_vma);
 			if (new_vma->vm_ops && new_vma->vm_ops->open)
 				new_vma->vm_ops->open(new_vma);
 			vma_link(mm, new_vma, prev, rb_link, rb_parent);
diff --git a/mm/nommu.c b/mm/nommu.c
index e544508..dd6f74a 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -693,7 +693,7 @@ static void __put_nommu_region(struct vm_region *region)
 		up_write(&nommu_region_sem);
 
 		if (region->vm_file)
-			fput(region->vm_file);
+			vmr_fput(region);
 
 		/* IO memory and memory shared directly out of the pagecache
 		 * from ramfs/tmpfs mustn't be released here */
@@ -858,7 +858,7 @@ static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 	if (vma->vm_ops && vma->vm_ops->close)
 		vma->vm_ops->close(vma);
 	if (vma->vm_file)
-		fput(vma->vm_file);
+		vma_fput(vma);
 	put_nommu_region(vma->vm_region);
 	kmem_cache_free(vm_area_cachep, vma);
 }
@@ -1398,7 +1398,7 @@ unsigned long do_mmap_pgoff(struct file *file,
 					goto error_just_free;
 				}
 			}
-			fput(region->vm_file);
+			vmr_fput(region);
 			kmem_cache_free(vm_region_jar, region);
 			region = pregion;
 			result = start;
@@ -1474,10 +1474,10 @@ error_just_free:
 	up_write(&nommu_region_sem);
 error:
 	if (region->vm_file)
-		fput(region->vm_file);
+		vmr_fput(region);
 	kmem_cache_free(vm_region_jar, region);
 	if (vma->vm_file)
-		fput(vma->vm_file);
+		vma_fput(vma);
 	kmem_cache_free(vm_area_cachep, vma);
 	kleave(" = %d", ret);
 	return ret;
diff --git a/mm/prfile.c b/mm/prfile.c
new file mode 100644
index 0000000..b323b8a
--- /dev/null
+++ b/mm/prfile.c
@@ -0,0 +1,86 @@
+/*
+ * Mainly for aufs which mmap(2) diffrent file and wants to print different path
+ * in /proc/PID/maps.
+ * Call these functions via macros defined in linux/mm.h.
+ *
+ * See Documentation/filesystems/aufs/design/06mmap.txt
+ *
+ * Copyright (c) 2014 Junjro R. Okajima
+ * Copyright (c) 2014 Ian Campbell
+ */
+
+#include <linux/mm.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+
+/* #define PRFILE_TRACE */
+static inline void prfile_trace(struct file *f, struct file *pr,
+			      const char func[], int line, const char func2[])
+{
+#ifdef PRFILE_TRACE
+	if (pr)
+		pr_info("%s:%d: %s, %s\n", func, line, func2,
+			f ? (char *)f->f_path.dentry->d_name.name : "(null)");
+#endif
+}
+
+void vma_do_file_update_time(struct vm_area_struct *vma, const char func[],
+			     int line)
+{
+	struct file *f = vma->vm_file, *pr = vma->vm_prfile;
+
+	prfile_trace(f, pr, func, line, __func__);
+	file_update_time(f);
+	if (f && pr)
+		file_update_time(pr);
+}
+
+struct file *vma_do_pr_or_file(struct vm_area_struct *vma, const char func[],
+			       int line)
+{
+	struct file *f = vma->vm_file, *pr = vma->vm_prfile;
+
+	prfile_trace(f, pr, func, line, __func__);
+	return (f && pr) ? pr : f;
+}
+
+void vma_do_get_file(struct vm_area_struct *vma, const char func[], int line)
+{
+	struct file *f = vma->vm_file, *pr = vma->vm_prfile;
+
+	prfile_trace(f, pr, func, line, __func__);
+	get_file(f);
+	if (f && pr)
+		get_file(pr);
+}
+
+void vma_do_fput(struct vm_area_struct *vma, const char func[], int line)
+{
+	struct file *f = vma->vm_file, *pr = vma->vm_prfile;
+
+	prfile_trace(f, pr, func, line, __func__);
+	fput(f);
+	if (f && pr)
+		fput(pr);
+}
+
+#ifndef CONFIG_MMU
+struct file *vmr_do_pr_or_file(struct vm_region *region, const char func[],
+			       int line)
+{
+	struct file *f = region->vm_file, *pr = region->vm_prfile;
+
+	prfile_trace(f, pr, func, line, __func__);
+	return (f && pr) ? pr : f;
+}
+
+void vmr_do_fput(struct vm_region *region, const char func[], int line)
+{
+	struct file *f = region->vm_file, *pr = region->vm_prfile;
+
+	prfile_trace(f, pr, func, line, __func__);
+	fput(f);
+	if (f && pr)
+		fput(pr);
+}
+#endif /* !CONFIG_MMU */