Commit 8d103963 authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
Browse files

userfaultfd: shmem: add shmem_mfill_zeropage_pte for userfaultfd support 

shmem_mfill_zeropage_pte is the low level routine that implements the
userfaultfd UFFDIO_ZEROPAGE command.  Since for shmem mappings zero
pages are always allocated and accounted, the new method is a slight
extension of the existing shmem_mcopy_atomic_pte.

Link: http://lkml.kernel.org/r/1497939652-16528-4-git-send-email-rppt@linux.vnet.ibm.com


Signed-off-by: default avatarMike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0f079694

include/linux/shmem_fs.h

+6 −0
Original line number Diff line number Diff line
@@ -137,9 +137,15 @@ extern int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, 
				  unsigned long dst_addr,

				  unsigned long src_addr,

				  struct page **pagep);

extern int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,

				    pmd_t *dst_pmd,

				    struct vm_area_struct *dst_vma,

				    unsigned long dst_addr);

#else

#define shmem_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \

			       src_addr, pagep)        ({ BUG(); 0; })

#define shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, \

				 dst_addr)      ({ BUG(); 0; })

#endif



#endif

mm/shmem.c

+45 −17
Original line number Diff line number Diff line
@@ -2207,11 +2207,12 @@ bool shmem_mapping(struct address_space *mapping) 
	return mapping->a_ops == &shmem_aops;

}



int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,

static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,

				  pmd_t *dst_pmd,

				  struct vm_area_struct *dst_vma,

				  unsigned long dst_addr,

				  unsigned long src_addr,

				  bool zeropage,

				  struct page **pagep)

{

	struct inode *inode = file_inode(dst_vma->vm_file);
@@ -2235,8 +2236,10 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, 
		if (!page)

			goto out_unacct_blocks;



		if (!zeropage) {	/* mcopy_atomic */

			page_kaddr = kmap_atomic(page);

		ret = copy_from_user(page_kaddr, (const void __user *)src_addr,

			ret = copy_from_user(page_kaddr,

					     (const void __user *)src_addr,

					     PAGE_SIZE);

			kunmap_atomic(page_kaddr);
@@ -2247,6 +2250,9 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, 
				/* don't free the page */

				return -EFAULT;

			}

		} else {		/* mfill_zeropage_atomic */

			clear_highpage(page);

		}

	} else {

		page = *pagep;

		*pagep = NULL;
@@ -2311,6 +2317,28 @@ out_unacct_blocks: 
	goto out;

}



int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,

			   pmd_t *dst_pmd,

			   struct vm_area_struct *dst_vma,

			   unsigned long dst_addr,

			   unsigned long src_addr,

			   struct page **pagep)

{

	return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,

				      dst_addr, src_addr, false, pagep);

}



int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,

			     pmd_t *dst_pmd,

			     struct vm_area_struct *dst_vma,

			     unsigned long dst_addr)

{

	struct page *page = NULL;



	return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,

				      dst_addr, 0, true, &page);

}



#ifdef CONFIG_TMPFS

static const struct inode_operations shmem_symlink_inode_operations;

static const struct inode_operations shmem_short_symlink_operations;

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