mm: userfaultfd: rename functions for clarity + consistency

Patch series "mm: userfaultfd: refactor and add UFFDIO_CONTINUE_MODE_WP",
v5.

- Commits 1-3 refactor userfaultfd ioctl code without behavior changes, with the
  main goal of improving consistency and reducing the number of function args.

- Commit 4 adds UFFDIO_CONTINUE_MODE_WP.


This patch (of 4):

The basic problem is, over time we've added new userfaultfd ioctls, and
we've refactored the code so functions which used to handle only one case
are now re-used to deal with several cases.  While this happened, we
didn't bother to rename the functions.

Similarly, as we added new functions, we cargo-culted pieces of the
now-inconsistent naming scheme, so those functions too ended up with names
that don't make a lot of sense.

A key point here is, "copy" in most userfaultfd code refers specifically
to UFFDIO_COPY, where we allocate a new page and copy its contents from
userspace.  There are many functions with "copy" in the name that don't
actually do this (at least in some cases).

So, rename things into a consistent scheme.  The high level idea is that
the call stack for userfaultfd ioctls becomes:

userfaultfd_ioctl
  -> userfaultfd_(particular ioctl)
    -> mfill_atomic_(particular kind of fill operation)
      -> mfill_atomic    /* loops over pages in range */
        -> mfill_atomic_pte    /* deals with single pages */
          -> mfill_atomic_pte_(particular kind of fill operation)
            -> mfill_atomic_install_pte

There are of course some special cases (shmem, hugetlb), but this is the
general structure which all function names now adhere to.

Link: https://lkml.kernel.org/r/20230314221250.682452-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20230314221250.682452-2-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 49 insertions, 49 deletions

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 23cabd02ac52..874379ce271f 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -127,13 +127,13 @@ out_unlock:
 	return ret;
 }
 
-static int 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,
-			    bool wp_copy)
+static int mfill_atomic_pte_copy(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,
+				 bool wp_copy)
 {
 	void *page_kaddr;
 	int ret;
@@ -204,10 +204,10 @@ out_release:
 	goto out;
 }
 
-static int mfill_zeropage_pte(struct mm_struct *dst_mm,
-			      pmd_t *dst_pmd,
-			      struct vm_area_struct *dst_vma,
-			      unsigned long dst_addr)
+static int mfill_atomic_pte_zeropage(struct mm_struct *dst_mm,
+				     pmd_t *dst_pmd,
+				     struct vm_area_struct *dst_vma,
+				     unsigned long dst_addr)
 {
 	pte_t _dst_pte, *dst_pte;
 	spinlock_t *ptl;
@@ -240,11 +240,11 @@ out_unlock:
 }
 
 /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */
-static int mcontinue_atomic_pte(struct mm_struct *dst_mm,
-				pmd_t *dst_pmd,
-				struct vm_area_struct *dst_vma,
-				unsigned long dst_addr,
-				bool wp_copy)
+static int mfill_atomic_pte_continue(struct mm_struct *dst_mm,
+				     pmd_t *dst_pmd,
+				     struct vm_area_struct *dst_vma,
+				     unsigned long dst_addr,
+				     bool wp_copy)
 {
 	struct inode *inode = file_inode(dst_vma->vm_file);
 	pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
@@ -307,10 +307,10 @@ static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
 
 #ifdef CONFIG_HUGETLB_PAGE
 /*
- * __mcopy_atomic processing for HUGETLB vmas.  Note that this routine is
+ * mfill_atomic processing for HUGETLB vmas.  Note that this routine is
  * called with mmap_lock held, it will release mmap_lock before returning.
  */
-static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
+static __always_inline ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm,
 					      struct vm_area_struct *dst_vma,
 					      unsigned long dst_start,
 					      unsigned long src_start,
@@ -411,7 +411,7 @@ retry:
 			goto out_unlock;
 		}
 
-		err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
+		err = hugetlb_mfill_atomic_pte(dst_mm, dst_pte, dst_vma,
 					       dst_addr, src_addr, mode, &page,
 					       wp_copy);
 
@@ -463,7 +463,7 @@ out:
 }
 #else /* !CONFIG_HUGETLB_PAGE */
 /* fail at build time if gcc attempts to use this */
-extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
+extern ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm,
 				      struct vm_area_struct *dst_vma,
 				      unsigned long dst_start,
 				      unsigned long src_start,
@@ -484,8 +484,8 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
 	ssize_t err;
 
 	if (mode == MCOPY_ATOMIC_CONTINUE) {
-		return mcontinue_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
-					    wp_copy);
+		return mfill_atomic_pte_continue(dst_mm, dst_pmd, dst_vma,
+						 dst_addr, wp_copy);
 	}
 
 	/*
@@ -500,11 +500,11 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
 	 */
 	if (!(dst_vma->vm_flags & VM_SHARED)) {
 		if (mode == MCOPY_ATOMIC_NORMAL)
-			err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
-					       dst_addr, src_addr, page,
-					       wp_copy);
+			err = mfill_atomic_pte_copy(dst_mm, dst_pmd, dst_vma,
+						    dst_addr, src_addr, page,
+						    wp_copy);
 		else
-			err = mfill_zeropage_pte(dst_mm, dst_pmd,
+			err = mfill_atomic_pte_zeropage(dst_mm, dst_pmd,
 						 dst_vma, dst_addr);
 	} else {
 		err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
@@ -516,13 +516,13 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
 	return err;
 }
 
-static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
-					      unsigned long dst_start,
-					      unsigned long src_start,
-					      unsigned long len,
-					      enum mcopy_atomic_mode mcopy_mode,
-					      atomic_t *mmap_changing,
-					      __u64 mode)
+static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm,
+					    unsigned long dst_start,
+					    unsigned long src_start,
+					    unsigned long len,
+					    enum mcopy_atomic_mode mcopy_mode,
+					    atomic_t *mmap_changing,
+					    __u64 mode)
 {
 	struct vm_area_struct *dst_vma;
 	ssize_t err;
@@ -588,9 +588,9 @@ retry:
 	 * If this is a HUGETLB vma, pass off to appropriate routine
 	 */
 	if (is_vm_hugetlb_page(dst_vma))
-		return  __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
-					       src_start, len, mcopy_mode,
-					       wp_copy);
+		return  mfill_atomic_hugetlb(dst_mm, dst_vma, dst_start,
+					     src_start, len, mcopy_mode,
+					     wp_copy);
 
 	if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
 		goto out_unlock;
@@ -688,26 +688,26 @@ out:
 	return copied ? copied : err;
 }
 
-ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
-		     unsigned long src_start, unsigned long len,
-		     atomic_t *mmap_changing, __u64 mode)
+ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start,
+			  unsigned long src_start, unsigned long len,
+			  atomic_t *mmap_changing, __u64 mode)
 {
-	return __mcopy_atomic(dst_mm, dst_start, src_start, len,
-			      MCOPY_ATOMIC_NORMAL, mmap_changing, mode);
+	return mfill_atomic(dst_mm, dst_start, src_start, len,
+			    MCOPY_ATOMIC_NORMAL, mmap_changing, mode);
 }
 
-ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
-		       unsigned long len, atomic_t *mmap_changing)
+ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start,
+			      unsigned long len, atomic_t *mmap_changing)
 {
-	return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE,
-			      mmap_changing, 0);
+	return mfill_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE,
+			    mmap_changing, 0);
 }
 
-ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long start,
-		       unsigned long len, atomic_t *mmap_changing)
+ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start,
+			      unsigned long len, atomic_t *mmap_changing)
 {
-	return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE,
-			      mmap_changing, 0);
+	return mfill_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE,
+			    mmap_changing, 0);
 }
 
 long uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma,