[RFC PATCH v2 09/19] mm/gup: Introduce vaddr_pin structure

[ira.weiny@xxxxxxxxx]

From: Ira Weiny <ira.weiny@xxxxxxxxx>

Some subsystems need to pass owning file information to GUP calls to
allow for GUP to associate the "owning file" to any files being pinned
within the GUP call.

Introduce an object to specify this information and pass it down through
some of the GUP call stack.

Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
---
 include/linux/mm.h |  9 +++++++++
 mm/gup.c           | 36 ++++++++++++++++++++++--------------
 2 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 04f22722b374..befe150d17be 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -971,6 +971,15 @@ static inline bool is_zone_device_page(const struct page *page)
 }
 #endif
 
+/**
+ * @f_owner The file who "owns this GUP"
+ * @mm The mm who "owns this GUP"
+ */
+struct vaddr_pin {
+	struct file *f_owner;
+	struct mm_struct *mm;
+};
+
 #ifdef CONFIG_DEV_PAGEMAP_OPS
 void __put_devmap_managed_page(struct page *page);
 DECLARE_STATIC_KEY_FALSE(devmap_managed_key);
diff --git a/mm/gup.c b/mm/gup.c
index 0b05e22ac05f..7a449500f0a6 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1005,7 +1005,8 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 						struct page **pages,
 						struct vm_area_struct **vmas,
 						int *locked,
-						unsigned int flags)
+						unsigned int flags,
+						struct vaddr_pin *vaddr_pin)
 {
 	long ret, pages_done;
 	bool lock_dropped;
@@ -1165,7 +1166,8 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 
 	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
 				       locked,
-				       gup_flags | FOLL_TOUCH | FOLL_REMOTE);
+				       gup_flags | FOLL_TOUCH | FOLL_REMOTE,
+				       NULL);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
@@ -1320,7 +1322,8 @@ static long __get_user_pages_locked(struct task_struct *tsk,
 		struct mm_struct *mm, unsigned long start,
 		unsigned long nr_pages, struct page **pages,
 		struct vm_area_struct **vmas, int *locked,
-		unsigned int foll_flags)
+		unsigned int foll_flags,
+		struct vaddr_pin *vaddr_pin)
 {
 	struct vm_area_struct *vma;
 	unsigned long vm_flags;
@@ -1504,7 +1507,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
 		 */
 		nr_pages = __get_user_pages_locked(tsk, mm, start, nr_pages,
 						   pages, vmas, NULL,
-						   gup_flags);
+						   gup_flags, NULL);
 
 		if ((nr_pages > 0) && migrate_allow) {
 			drain_allow = true;
@@ -1537,7 +1540,8 @@ static long __gup_longterm_locked(struct task_struct *tsk,
 				  unsigned long nr_pages,
 				  struct page **pages,
 				  struct vm_area_struct **vmas,
-				  unsigned int gup_flags)
+				  unsigned int gup_flags,
+				  struct vaddr_pin *vaddr_pin)
 {
 	struct vm_area_struct **vmas_tmp = vmas;
 	unsigned long flags = 0;
@@ -1558,7 +1562,7 @@ static long __gup_longterm_locked(struct task_struct *tsk,
 	}
 
 	rc = __get_user_pages_locked(tsk, mm, start, nr_pages, pages,
-				     vmas_tmp, NULL, gup_flags);
+				     vmas_tmp, NULL, gup_flags, vaddr_pin);
 
 	if (gup_flags & FOLL_LONGTERM) {
 		memalloc_nocma_restore(flags);
@@ -1588,10 +1592,11 @@ static __always_inline long __gup_longterm_locked(struct task_struct *tsk,
 						  unsigned long nr_pages,
 						  struct page **pages,
 						  struct vm_area_struct **vmas,
-						  unsigned int flags)
+						  unsigned int flags,
+						  struct vaddr_pin *vaddr_pin)
 {
 	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
-				       NULL, flags);
+				       NULL, flags, vaddr_pin);
 }
 #endif /* CONFIG_FS_DAX || CONFIG_CMA */
 
@@ -1607,7 +1612,8 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 		struct vm_area_struct **vmas)
 {
 	return __gup_longterm_locked(current, current->mm, start, nr_pages,
-				     pages, vmas, gup_flags | FOLL_TOUCH);
+				     pages, vmas, gup_flags | FOLL_TOUCH,
+				     NULL);
 }
 EXPORT_SYMBOL(get_user_pages);
 
@@ -1647,7 +1653,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
 				       pages, NULL, locked,
-				       gup_flags | FOLL_TOUCH);
+				       gup_flags | FOLL_TOUCH, NULL);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
@@ -1684,7 +1690,7 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 
 	down_read(&mm->mmap_sem);
 	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
-				      &locked, gup_flags | FOLL_TOUCH);
+				      &locked, gup_flags | FOLL_TOUCH, NULL);
 	if (locked)
 		up_read(&mm->mmap_sem);
 	return ret;
@@ -2377,7 +2383,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 EXPORT_SYMBOL_GPL(__get_user_pages_fast);
 
 static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
-				   unsigned int gup_flags, struct page **pages)
+				   unsigned int gup_flags, struct page **pages,
+				   struct vaddr_pin *vaddr_pin)
 {
 	int ret;
 
@@ -2389,7 +2396,8 @@ static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
 		down_read(&current->mm->mmap_sem);
 		ret = __gup_longterm_locked(current, current->mm,
 					    start, nr_pages,
-					    pages, NULL, gup_flags);
+					    pages, NULL, gup_flags,
+					    vaddr_pin);
 		up_read(&current->mm->mmap_sem);
 	} else {
 		ret = get_user_pages_unlocked(start, nr_pages,
@@ -2448,7 +2456,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 		pages += nr;
 
 		ret = __gup_longterm_unlocked(start, nr_pages - nr,
-					      gup_flags, pages);
+					      gup_flags, pages, NULL);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {
-- 
2.20.1