mm: kill vma flag VM_CAN_NONLINEAR

Move actual pte filling for non-linear file mappings into the new special
vma operation: ->remap_pages().

Filesystems must implement this method to get non-linear mapping support,
if it uses filemap_fault() then generic_file_remap_pages() can be used.

Now device drivers can implement this method and obtain nonlinear vma support.

Signed-off-by: Konstantin Khlebnikov <[e-mail]>
Cc: Alexander Viro <[e-mail]>
Cc: Carsten Otte <[e-mail]>
Cc: Chris Metcalf <[e-mail]> #arch/tile
Cc: Cyrill Gorcunov <[e-mail]>
Cc: Eric Paris <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Morris <[e-mail]>
Cc: Jason Baron <[e-mail]>
Cc: Kentaro Takeda <[e-mail]>
Cc: Matt Helsley <[e-mail]>
Cc: Nick Piggin <[e-mail]>
Cc: Oleg Nesterov <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Robert Richter <[e-mail]>
Cc: Suresh Siddha <[e-mail]>
Cc: Tetsuo Handa <[e-mail]>
Cc: Venkatesh Pallipadi <[e-mail]>
Acked-by: Linus Torvalds <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/staging/android/ashmem.c

···
 	if (vma->vm_file)
 		fput(vma->vm_file);
 	vma->vm_file = asma->file;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 
 out:
 	mutex_unlock(&ashmem_mutex);

fs/9p/vfs_file.c

···
 static const struct vm_operations_struct v9fs_file_vm_ops = {
 	.fault = filemap_fault,
 	.page_mkwrite = v9fs_vm_page_mkwrite,
+	.remap_pages = generic_file_remap_pages,
 };
 
 

fs/btrfs/file.c

···
 static const struct vm_operations_struct btrfs_file_vm_ops = {
 	.fault		= filemap_fault,
 	.page_mkwrite	= btrfs_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };
 
 static int btrfs_file_mmap(struct file	*filp, struct vm_area_struct *vma)
···
 
 	file_accessed(filp);
 	vma->vm_ops = &btrfs_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 
 	return 0;
 }

fs/ceph/addr.c

···
 static struct vm_operations_struct ceph_vmops = {
 	.fault		= filemap_fault,
 	.page_mkwrite	= ceph_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };
 
 int ceph_mmap(struct file *file, struct vm_area_struct *vma)
···
 		return -ENOEXEC;
 	file_accessed(file);
 	vma->vm_ops = &ceph_vmops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }

fs/cifs/file.c

···
 static struct vm_operations_struct cifs_file_vm_ops = {
 	.fault = filemap_fault,
 	.page_mkwrite = cifs_page_mkwrite,
+	.remap_pages = generic_file_remap_pages,
 };
 
 int cifs_file_strict_mmap(struct file *file, struct vm_area_struct *vma)

fs/ext4/file.c

···
 static const struct vm_operations_struct ext4_file_vm_ops = {
 	.fault		= filemap_fault,
 	.page_mkwrite   = ext4_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };
 
 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
···
 		return -ENOEXEC;
 	file_accessed(file);
 	vma->vm_ops = &ext4_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 

fs/fuse/file.c

···
 	.close		= fuse_vma_close,
 	.fault		= filemap_fault,
 	.page_mkwrite	= fuse_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };
 
 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)

fs/gfs2/file.c

···
 static const struct vm_operations_struct gfs2_vm_ops = {
 	.fault = filemap_fault,
 	.page_mkwrite = gfs2_page_mkwrite,
+	.remap_pages = generic_file_remap_pages,
 };
 
 /**
···
 			return error;
 	}
 	vma->vm_ops = &gfs2_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 
 	return 0;
 }

fs/nfs/file.c

···
 static const struct vm_operations_struct nfs_file_vm_ops = {
 	.fault = filemap_fault,
 	.page_mkwrite = nfs_vm_page_mkwrite,
+	.remap_pages = generic_file_remap_pages,
 };
 
 static int nfs_need_sync_write(struct file *filp, struct inode *inode)

fs/nilfs2/file.c

···
 static const struct vm_operations_struct nilfs_file_vm_ops = {
 	.fault		= filemap_fault,
 	.page_mkwrite	= nilfs_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };
 
 static int nilfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	file_accessed(file);
 	vma->vm_ops = &nilfs_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 

fs/ocfs2/mmap.c

···
 static const struct vm_operations_struct ocfs2_file_vm_ops = {
 	.fault		= ocfs2_fault,
 	.page_mkwrite	= ocfs2_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };
 
 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
···
 	ocfs2_inode_unlock(file->f_dentry->d_inode, lock_level);
 out:
 	vma->vm_ops = &ocfs2_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 

fs/ubifs/file.c

···
 static const struct vm_operations_struct ubifs_file_vm_ops = {
 	.fault        = filemap_fault,
 	.page_mkwrite = ubifs_vm_page_mkwrite,
+	.remap_pages = generic_file_remap_pages,
 };
 
 static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)

fs/xfs/xfs_file.c

···
 	struct vm_area_struct *vma)
 {
 	vma->vm_ops = &xfs_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 
 	file_accessed(filp);
 	return 0;
···
 static const struct vm_operations_struct xfs_file_vm_ops = {
 	.fault		= filemap_fault,
 	.page_mkwrite	= xfs_vm_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };

include/linux/fs.h

···
 
 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
+extern int generic_file_remap_pages(struct vm_area_struct *, unsigned long addr,
+		unsigned long size, pgoff_t pgoff);
 extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
 int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
 extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);

include/linux/mm.h

···
 #define VM_ARCH_1	0x01000000	/* Architecture-specific flag */
 #define VM_NODUMP	0x04000000	/* Do not include in the core dump */
 
-#define VM_CAN_NONLINEAR 0x08000000	/* Has ->fault & does nonlinear pages */
 #define VM_MIXEDMAP	0x10000000	/* Can contain "struct page" and pure PFN pages */
 #define VM_HUGEPAGE	0x20000000	/* MADV_HUGEPAGE marked this vma */
 #define VM_NOHUGEPAGE	0x40000000	/* MADV_NOHUGEPAGE marked this vma */
···
  * of VM_FAULT_xxx flags that give details about how the fault was handled.
  *
  * pgoff should be used in favour of virtual_address, if possible. If pgoff
- * is used, one may set VM_CAN_NONLINEAR in the vma->vm_flags to get nonlinear
- * mapping support.
+ * is used, one may implement ->remap_pages to get nonlinear mapping support.
  */
 struct vm_fault {
 	unsigned int flags;		/* FAULT_FLAG_xxx flags */
···
 	int (*migrate)(struct vm_area_struct *vma, const nodemask_t *from,
 		const nodemask_t *to, unsigned long flags);
 #endif
+	/* called by sys_remap_file_pages() to populate non-linear mapping */
+	int (*remap_pages)(struct vm_area_struct *vma, unsigned long addr,
+			   unsigned long size, pgoff_t pgoff);
 };
 
 struct mmu_gather;

mm/filemap.c

···
 const struct vm_operations_struct generic_file_vm_ops = {
 	.fault		= filemap_fault,
 	.page_mkwrite	= filemap_page_mkwrite,
+	.remap_pages	= generic_file_remap_pages,
 };
 
 /* This is used for a general mmap of a disk file */
···
 		return -ENOEXEC;
 	file_accessed(file);
 	vma->vm_ops = &generic_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 

mm/filemap_xip.c

···
 static const struct vm_operations_struct xip_file_vm_ops = {
 	.fault	= xip_file_fault,
 	.page_mkwrite	= filemap_page_mkwrite,
+	.remap_pages = generic_file_remap_pages,
 };
 
 int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
···
 
 	file_accessed(file);
 	vma->vm_ops = &xip_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR | VM_MIXEDMAP;
+	vma->vm_flags |= VM_MIXEDMAP;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xip_file_mmap);

mm/fremap.c

···
  *
  * started by Ingo Molnar, Copyright (C) 2002, 2003
  */
+#include <linux/export.h>
 #include <linux/backing-dev.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
···
 	return err;
 }
 
-static int populate_range(struct mm_struct *mm, struct vm_area_struct *vma,
-			unsigned long addr, unsigned long size, pgoff_t pgoff)
+int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
+			     unsigned long size, pgoff_t pgoff)
 {
+	struct mm_struct *mm = vma->vm_mm;
 	int err;
 
 	do {
···
 		pgoff++;
 	} while (size);
 
-        return 0;
-
+	return 0;
 }
+EXPORT_SYMBOL(generic_file_remap_pages);
 
 /**
  * sys_remap_file_pages - remap arbitrary pages of an existing VM_SHARED vma
···
 	if (vma->vm_private_data && !(vma->vm_flags & VM_NONLINEAR))
 		goto out;
 
-	if (!(vma->vm_flags & VM_CAN_NONLINEAR))
+	if (!vma->vm_ops->remap_pages)
 		goto out;
 
 	if (start < vma->vm_start || start + size > vma->vm_end)
···
 	}
 
 	mmu_notifier_invalidate_range_start(mm, start, start + size);
-	err = populate_range(mm, vma, start, size, pgoff);
+	err = vma->vm_ops->remap_pages(vma, start, size, pgoff);
 	mmu_notifier_invalidate_range_end(mm, start, start + size);
 	if (!err && !(flags & MAP_NONBLOCK)) {
 		if (vma->vm_flags & VM_LOCKED) {

mm/mmap.c

···
 static inline int is_mergeable_vma(struct vm_area_struct *vma,
 			struct file *file, unsigned long vm_flags)
 {
-	/* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
-	if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
+	if (vma->vm_flags ^ vm_flags)
 		return 0;
 	if (vma->vm_file != file)
 		return 0;

mm/nommu.c

···
 }
 EXPORT_SYMBOL(filemap_fault);
 
+int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
+			     unsigned long size, pgoff_t pgoff)
+{
+	BUG();
+	return 0;
+}
+EXPORT_SYMBOL(generic_file_remap_pages);
+
 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 		unsigned long addr, void *buf, int len, int write)
 {

mm/shmem.c

···
 {
 	file_accessed(file);
 	vma->vm_ops = &shmem_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 
···
 	.set_policy     = shmem_set_policy,
 	.get_policy     = shmem_get_policy,
 #endif
+	.remap_pages	= generic_file_remap_pages,
 };
 
 static struct dentry *shmem_mount(struct file_system_type *fs_type,
···
 		fput(vma->vm_file);
 	vma->vm_file = file;
 	vma->vm_ops = &shmem_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }