path: root/features/aufs/aufs6-mmap.patch

From 550fbd6a226ed0b04b497dd4dcf5e14c7cd113f1 Mon Sep 17 00:00:00 2001
From: Bruce Ashfield <bruce.ashfield@gmail.com>
Date: Thu, 21 Sep 2023 17:49:39 -0400
Subject: [PATCH] aufs6: mmap

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
---
 fs/proc/base.c           |  2 +-
 fs/proc/nommu.c          |  5 ++-
 fs/proc/task_mmu.c       |  6 ++-
 fs/proc/task_nommu.c     |  5 ++-
 include/linux/mm.h       | 37 +++++++++++++++++
 include/linux/mm_types.h |  6 +++
 kernel/fork.c            |  2 +-
 mm/Makefile              |  1 +
 mm/filemap.c             |  2 +-
 mm/mmap.c                | 41 +++++++++++++++----
 mm/nommu.c               | 10 ++---
 mm/prfile.c              | 86 ++++++++++++++++++++++++++++++++++++++++
 12 files changed, 184 insertions(+), 19 deletions(-)
 create mode 100644 mm/prfile.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 98a031ac2648..9cd1d25f9fc0 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2215,7 +2215,7 @@ static int map_files_get_link(struct dentry *dentry, struct path *path)
 	rc = -ENOENT;
 	vma = find_exact_vma(mm, vm_start, vm_end);
 	if (vma && vma->vm_file) {
-		*path = *file_user_path(vma->vm_file);
+		*path = *file_user_path(vma_pr_or_file(vma));
 		path_get(path);
 		rc = 0;
 	}
diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
index c6e7ebc63756..d7ccfd909764 100644
--- a/fs/proc/nommu.c
+++ b/fs/proc/nommu.c
@@ -39,7 +39,10 @@ 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 3f78ebbb795f..32f9aaf5345e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -273,8 +273,10 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 	const char *name = NULL;
 
 	if (file) {
-		const struct inode *inode = file_user_inode(vma->vm_file);
+		struct inode *inode;
 
+		file = vma_pr_or_file(vma);
+		inode = file_user_inode(vma->vm_file);
 		dev = inode->i_sb->s_dev;
 		ino = inode->i_ino;
 		pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
@@ -2701,7 +2703,7 @@ static int show_numa_map(struct seq_file *m, void *v)
 	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;
 	char buffer[64];
 	struct mempolicy *pol;
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index bce674533000..b12b5a75c799 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -137,7 +137,10 @@ 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 f5a97dec5169..dc908f541ce9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2432,6 +2432,43 @@ static inline void unmap_shared_mapping_range(struct address_space *mapping,
 static inline struct vm_area_struct *vma_lookup(struct mm_struct *mm,
 						unsigned long addr);
 
+#if 1 /* IS_ENABLED(CONFIG_AUFS_FS) */
+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 */
+
+#else
+
+#define vma_file_update_time(vma)	file_update_time((vma)->vm_file)
+#define vma_pr_or_file(vma)		(vma)->vm_file
+#define vma_get_file(vma)		get_file((vma)->vm_file)
+#define vma_fput(vma)			fput((vma)->vm_file)
+
+#ifndef CONFIG_MMU
+#define vmr_pr_or_file(region)		(region)->vm_file
+#define vmr_fput(region)		fput((region)->vm_file)
+#endif /* !CONFIG_MMU */
+
+#endif /* CONFIG_AUFS_FS */
+
 extern int access_process_vm(struct task_struct *tsk, unsigned long addr,
 		void *buf, int len, unsigned int gup_flags);
 extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8b611e13153e..f5f10bfa5b63 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -527,6 +527,9 @@ 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 */
+#if 1 /* IS_ENABLED(CONFIG_AUFS_FS) */
+	struct file	*vm_prfile;	/* the virtual backing file or NULL */
+#endif
 
 	int		vm_usage;	/* region usage count (access under nommu_region_sem) */
 	bool		vm_icache_flushed : 1; /* true if the icache has been flushed for
@@ -691,6 +694,9 @@ struct vm_area_struct {
 	unsigned long vm_pgoff;		/* Offset (within vm_file) in PAGE_SIZE
 					   units */
 	struct file * vm_file;		/* File we map to (can be NULL). */
+#if 1 /* IS_ENABLED(CONFIG_AUFS_FS) */
+	struct file *vm_prfile;		/* shadow of vm_file */
+#endif
 	void * vm_private_data;		/* was vm_pte (shared mem) */
 
 #ifdef CONFIG_ANON_VMA_NAME
diff --git a/kernel/fork.c b/kernel/fork.c
index 47ff3b35352e..41a80f248514 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -716,7 +716,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 		if (file) {
 			struct address_space *mapping = file->f_mapping;
 
-			get_file(file);
+			vma_get_file(tmp);
 			i_mmap_lock_write(mapping);
 			if (vma_is_shared_maywrite(tmp))
 				mapping_allow_writable(mapping);
diff --git a/mm/Makefile b/mm/Makefile
index e4b5b75aaec9..d69ba9efb769 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -134,3 +134,4 @@ obj-$(CONFIG_IO_MAPPING) += io-mapping.o
 obj-$(CONFIG_HAVE_BOOTMEM_INFO_NODE) += bootmem_info.o
 obj-$(CONFIG_GENERIC_IOREMAP) += ioremap.o
 obj-$(CONFIG_SHRINKER_DEBUG) += shrinker_debug.o
+obj-y += prfile.o
diff --git a/mm/filemap.c b/mm/filemap.c
index 750e779c23db..b84a752ff676 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3587,7 +3587,7 @@ vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
 	vm_fault_t ret = VM_FAULT_LOCKED;
 
 	sb_start_pagefault(mapping->host->i_sb);
-	file_update_time(vmf->vma->vm_file);
+	vma_file_update_time(vmf->vma);
 	folio_lock(folio);
 	if (folio->mapping != mapping) {
 		folio_unlock(folio);
diff --git a/mm/mmap.c b/mm/mmap.c
index b78e83d351d2..e2ae3999a51c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -140,7 +140,7 @@ static void remove_vma(struct vm_area_struct *vma, bool unreachable)
 	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));
 	if (unreachable)
 		__vm_area_free(vma);
@@ -554,7 +554,7 @@ static inline void vma_complete(struct vma_prepare *vp,
 		if (vp->file) {
 			uprobe_munmap(vp->remove, vp->remove->vm_start,
 				      vp->remove->vm_end);
-			fput(vp->file);
+			vma_fput(vp->vma);
 		}
 		if (vp->remove->anon_vma)
 			anon_vma_merge(vp->vma, vp->remove);
@@ -2355,7 +2355,7 @@ static int __split_vma(struct vma_iterator *vmi, 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);
@@ -2853,7 +2853,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 				 * and cause general protection fault
 				 * ultimately.
 				 */
-				fput(vma->vm_file);
+				vma_fput(vma);
 				vm_area_free(vma);
 				vma = merge;
 				/* Update vm_flags to pick up the change. */
@@ -2948,7 +2948,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 
 	if (file || vma->vm_file) {
 unmap_and_free_vma:
-		fput(vma->vm_file);
+		vma_fput(vma);
 		vma->vm_file = NULL;
 
 		vma_iter_set(&vmi, vma->vm_end);
@@ -3010,6 +3010,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 	unsigned long populate = 0;
 	unsigned long ret = -EINVAL;
 	struct file *file;
+#if 1 /* IS_ENABLED(CONFIG_AUFS_FS) */
+	struct file *prfile;
+#endif
 
 	pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n",
 		     current->comm, current->pid);
@@ -3068,10 +3071,34 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 	if (vma->vm_flags & VM_LOCKED)
 		flags |= MAP_LOCKED;
 
+#if 1 /* IS_ENABLED(CONFIG_AUFS_FS) */
+	vma_get_file(vma);
+	file = vma->vm_file;
+	prfile = vma->vm_prfile;
+	ret = do_mmap(vma->vm_file, start, size,
+			prot, flags, pgoff, &populate, NULL);
+	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 (prfile)
+			get_file(prfile);
+	}
+	/*
+	 * two fput()s instead of vma_fput(vma),
+	 * coz vma may not be available anymore.
+	 */
+	fput(file);
+	if (prfile)
+		fput(prfile);
+#else
 	file = get_file(vma->vm_file);
 	ret = do_mmap(vma->vm_file, start, size,
 			prot, flags, 0, pgoff, &populate, NULL);
 	fput(file);
+#endif /* CONFIG_AUFS_FS */
 out:
 	mmap_write_unlock(mm);
 	if (populate)
@@ -3418,7 +3445,7 @@ 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);
 		if (vma_link(mm, new_vma))
@@ -3432,7 +3459,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 		new_vma->vm_ops->close(new_vma);
 
 	if (new_vma->vm_file)
-		fput(new_vma->vm_file);
+		vma_fput(new_vma);
 
 	unlink_anon_vmas(new_vma);
 out_free_mempol:
diff --git a/mm/nommu.c b/mm/nommu.c
index b6dc558d3144..d96655486468 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -523,7 +523,7 @@ 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 */
@@ -603,7 +603,7 @@ 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);
 	vm_area_free(vma);
 }
@@ -1135,7 +1135,7 @@ unsigned long do_mmap(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;
@@ -1221,10 +1221,10 @@ unsigned long do_mmap(struct file *file,
 error:
 	vma_iter_free(&vmi);
 	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);
 	vm_area_free(vma);
 	return ret;
 
diff --git a/mm/prfile.c b/mm/prfile.c
new file mode 100644
index 000000000000..8f820a235364
--- /dev/null
+++ b/mm/prfile.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Mainly for aufs which mmap(2) different 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) 2014-2022 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, %pD2\n", func, line, func2, f);
+#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 */
-- 
2.39.2