mm: join struct fault_env and vm_fault

Currently we have two different structures for passing fault information
around - struct vm_fault and struct fault_env.  DAX will need more
information in struct vm_fault to handle its faults so the content of
that structure would become event closer to fault_env.  Furthermore it
would need to generate struct fault_env to be able to call some of the
generic functions.  So at this point I don't think there's much use in
keeping these two structures separate.  Just embed into struct vm_fault
all that is needed to use it for both purposes.

Link: http://lkml.kernel.org/r/1479460644-25076-2-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: jankara

Documentation/filesystems/Locking

@@ -556,7 +556,7 @@ till "end_pgoff". ->map_pages() is called with page table locked and must
 not block.  If it's not possible to reach a page without blocking,
 filesystem should skip it. Filesystem should use do_set_pte() to setup
 page table entry. Pointer to entry associated with the page is passed in
-"pte" field in fault_env structure. Pointers to entries for other offsets
+"pte" field in vm_fault structure. Pointers to entries for other offsets
 should be calculated relative to "pte".
 
 	->page_mkwrite() is called when a previously read-only pte is

fs/userfaultfd.c

@@ -257,9 +257,9 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
  * fatal_signal_pending()s, and the mmap_sem must be released before
  * returning it.
  */
-int handle_userfault(struct fault_env *fe, unsigned long reason)
+int handle_userfault(struct vm_fault *vmf, unsigned long reason)
 {
-	struct mm_struct *mm = fe->vma->vm_mm;
+	struct mm_struct *mm = vmf->vma->vm_mm;
 	struct userfaultfd_ctx *ctx;
 	struct userfaultfd_wait_queue uwq;
 	int ret;
@@ -268,7 +268,7 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 	BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
 
 	ret = VM_FAULT_SIGBUS;
-	ctx = fe->vma->vm_userfaultfd_ctx.ctx;
+	ctx = vmf->vma->vm_userfaultfd_ctx.ctx;
 	if (!ctx)
 		goto out;
 
@@ -301,17 +301,18 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 	 * without first stopping userland access to the memory. For
 	 * VM_UFFD_MISSING userfaults this is enough for now.
 	 */
-	if (unlikely(!(fe->flags & FAULT_FLAG_ALLOW_RETRY))) {
+	if (unlikely(!(vmf->flags & FAULT_FLAG_ALLOW_RETRY))) {
 		/*
 		 * Validate the invariant that nowait must allow retry
 		 * to be sure not to return SIGBUS erroneously on
 		 * nowait invocations.
 		 */
-		BUG_ON(fe->flags & FAULT_FLAG_RETRY_NOWAIT);
+		BUG_ON(vmf->flags & FAULT_FLAG_RETRY_NOWAIT);
 #ifdef CONFIG_DEBUG_VM
 		if (printk_ratelimit()) {
 			printk(KERN_WARNING
-			       "FAULT_FLAG_ALLOW_RETRY missing %x\n", fe->flags);
+			       "FAULT_FLAG_ALLOW_RETRY missing %x\n",
+			       vmf->flags);
 			dump_stack();
 		}
 #endif
@@ -323,19 +324,19 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 	 * and wait.
 	 */
 	ret = VM_FAULT_RETRY;
-	if (fe->flags & FAULT_FLAG_RETRY_NOWAIT)
+	if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
 		goto out;
 
 	/* take the reference before dropping the mmap_sem */
 	userfaultfd_ctx_get(ctx);
 
 	init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function);
 	uwq.wq.private = current;
-	uwq.msg = userfault_msg(fe->address, fe->flags, reason);
+	uwq.msg = userfault_msg(vmf->address, vmf->flags, reason);
 	uwq.ctx = ctx;
 
 	return_to_userland =
-		(fe->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) ==
+		(vmf->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) ==
 		(FAULT_FLAG_USER|FAULT_FLAG_KILLABLE);
 
 	spin_lock(&ctx->fault_pending_wqh.lock);
@@ -353,7 +354,8 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 			  TASK_KILLABLE);
 	spin_unlock(&ctx->fault_pending_wqh.lock);
 
-	must_wait = userfaultfd_must_wait(ctx, fe->address, fe->flags, reason);
+	must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
+					  reason);
 	up_read(&mm->mmap_sem);
 
 	if (likely(must_wait && !ACCESS_ONCE(ctx->released) &&

include/linux/huge_mm.h

@@ -1,12 +1,12 @@
 #ifndef _LINUX_HUGE_MM_H
 #define _LINUX_HUGE_MM_H
 
-extern int do_huge_pmd_anonymous_page(struct fault_env *fe);
+extern int do_huge_pmd_anonymous_page(struct vm_fault *vmf);
 extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 			 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
 			 struct vm_area_struct *vma);
-extern void huge_pmd_set_accessed(struct fault_env *fe, pmd_t orig_pmd);
-extern int do_huge_pmd_wp_page(struct fault_env *fe, pmd_t orig_pmd);
+extern void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd);
+extern int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd);
 extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 					  unsigned long addr,
 					  pmd_t *pmd,
@@ -142,7 +142,7 @@ static inline int hpage_nr_pages(struct page *page)
 	return 1;
 }
 
-extern int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t orig_pmd);
+extern int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t orig_pmd);
 
 extern struct page *huge_zero_page;
 
@@ -212,7 +212,7 @@ static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
 	return NULL;
 }
 
-static inline int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t orig_pmd)
+static inline int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t orig_pmd)
 {
 	return 0;
 }

include/linux/mm.h

@@ -292,10 +292,16 @@ extern pgprot_t protection_map[16];
  * pgoff should be used in favour of virtual_address, if possible.
  */
 struct vm_fault {
+	struct vm_area_struct *vma;	/* Target VMA */
 	unsigned int flags;		/* FAULT_FLAG_xxx flags */
 	gfp_t gfp_mask;			/* gfp mask to be used for allocations */
 	pgoff_t pgoff;			/* Logical page offset based on vma */
-	void __user *virtual_address;	/* Faulting virtual address */
+	unsigned long address;		/* Faulting virtual address */
+	void __user *virtual_address;	/* Faulting virtual address masked by
+					 * PAGE_MASK */
+	pmd_t *pmd;			/* Pointer to pmd entry matching
+					 * the 'address'
+					 */
 
 	struct page *cow_page;		/* Handler may choose to COW */
 	struct page *page;		/* ->fault handlers should return a
@@ -309,19 +315,7 @@ struct vm_fault {
 					 * VM_FAULT_DAX_LOCKED and fill in
 					 * entry here.
 					 */
-};
-
-/*
- * Page fault context: passes though page fault handler instead of endless list
- * of function arguments.
- */
-struct fault_env {
-	struct vm_area_struct *vma;	/* Target VMA */
-	unsigned long address;		/* Faulting virtual address */
-	unsigned int flags;		/* FAULT_FLAG_xxx flags */
-	pmd_t *pmd;			/* Pointer to pmd entry matching
-					 * the 'address'
-					 */
+	/* These three entries are valid only while holding ptl lock */
 	pte_t *pte;			/* Pointer to pte entry matching
 					 * the 'address'. NULL if the page
 					 * table hasn't been allocated.
@@ -351,7 +345,7 @@ struct vm_operations_struct {
 	int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
 	int (*pmd_fault)(struct vm_area_struct *, unsigned long address,
 						pmd_t *, unsigned int flags);
-	void (*map_pages)(struct fault_env *fe,
+	void (*map_pages)(struct vm_fault *vmf,
 			pgoff_t start_pgoff, pgoff_t end_pgoff);
 
 	/* notification that a previously read-only page is about to become
@@ -625,7 +619,7 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
 	return pte;
 }
 
-int alloc_set_pte(struct fault_env *fe, struct mem_cgroup *memcg,
+int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
 		struct page *page);
 #endif
 
@@ -2094,7 +2088,7 @@ extern void truncate_inode_pages_final(struct address_space *);
 
 /* generic vm_area_ops exported for stackable file systems */
 extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
-extern void filemap_map_pages(struct fault_env *fe,
+extern void filemap_map_pages(struct vm_fault *vmf,
 		pgoff_t start_pgoff, pgoff_t end_pgoff);
 extern int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
 

include/linux/userfaultfd_k.h

@@ -27,7 +27,7 @@
 #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
 #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
 
-extern int handle_userfault(struct fault_env *fe, unsigned long reason);
+extern int handle_userfault(struct vm_fault *vmf, unsigned long reason);
 
 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
 			    unsigned long src_start, unsigned long len);
@@ -55,7 +55,7 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma)
 #else /* CONFIG_USERFAULTFD */
 
 /* mm helpers */
-static inline int handle_userfault(struct fault_env *fe, unsigned long reason)
+static inline int handle_userfault(struct vm_fault *vmf, unsigned long reason)
 {
 	return VM_FAULT_SIGBUS;
 }

mm/filemap.c

@@ -2164,12 +2164,12 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 }
 EXPORT_SYMBOL(filemap_fault);
 
-void filemap_map_pages(struct fault_env *fe,
+void filemap_map_pages(struct vm_fault *vmf,
 		pgoff_t start_pgoff, pgoff_t end_pgoff)
 {
 	struct radix_tree_iter iter;
 	void **slot;
-	struct file *file = fe->vma->vm_file;
+	struct file *file = vmf->vma->vm_file;
 	struct address_space *mapping = file->f_mapping;
 	pgoff_t last_pgoff = start_pgoff;
 	loff_t size;
@@ -2225,11 +2225,11 @@ void filemap_map_pages(struct fault_env *fe,
 		if (file->f_ra.mmap_miss > 0)
 			file->f_ra.mmap_miss--;
 
-		fe->address += (iter.index - last_pgoff) << PAGE_SHIFT;
-		if (fe->pte)
-			fe->pte += iter.index - last_pgoff;
+		vmf->address += (iter.index - last_pgoff) << PAGE_SHIFT;
+		if (vmf->pte)
+			vmf->pte += iter.index - last_pgoff;
 		last_pgoff = iter.index;
-		if (alloc_set_pte(fe, NULL, page))
+		if (alloc_set_pte(vmf, NULL, page))
 			goto unlock;
 		unlock_page(page);
 		goto next;
@@ -2239,7 +2239,7 @@ void filemap_map_pages(struct fault_env *fe,
 		put_page(page);
 next:
 		/* Huge page is mapped? No need to proceed. */
-		if (pmd_trans_huge(*fe->pmd))
+		if (pmd_trans_huge(*vmf->pmd))
 			break;
 		if (iter.index == end_pgoff)
 			break;