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>

2 files changed, 24 insertions, 24 deletions

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 8fb7d91cd0b1..152434396c48 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -158,13 +158,13 @@ unsigned long hugetlb_total_pages(void);
 vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 			unsigned long address, unsigned int flags);
 #ifdef CONFIG_USERFAULTFD
-int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
-				struct vm_area_struct *dst_vma,
-				unsigned long dst_addr,
-				unsigned long src_addr,
-				enum mcopy_atomic_mode mode,
-				struct page **pagep,
-				bool wp_copy);
+int hugetlb_mfill_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
+			     struct vm_area_struct *dst_vma,
+			     unsigned long dst_addr,
+			     unsigned long src_addr,
+			     enum mcopy_atomic_mode mode,
+			     struct page **pagep,
+			     bool wp_copy);
 #endif /* CONFIG_USERFAULTFD */
 bool hugetlb_reserve_pages(struct inode *inode, long from, long to,
 						struct vm_area_struct *vma,
@@ -393,14 +393,14 @@ static inline void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 }
 
 #ifdef CONFIG_USERFAULTFD
-static inline int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
-						pte_t *dst_pte,
-						struct vm_area_struct *dst_vma,
-						unsigned long dst_addr,
-						unsigned long src_addr,
-						enum mcopy_atomic_mode mode,
-						struct page **pagep,
-						bool wp_copy)
+static inline int hugetlb_mfill_atomic_pte(struct mm_struct *dst_mm,
+					   pte_t *dst_pte,
+					   struct vm_area_struct *dst_vma,
+					   unsigned long dst_addr,
+					   unsigned long src_addr,
+					   enum mcopy_atomic_mode mode,
+					   struct page **pagep,
+					   bool wp_copy)
 {
 	BUG();
 	return 0;
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 0cf8880219da..ac178d810dc7 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -61,15 +61,15 @@ extern int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
 				    unsigned long dst_addr, struct page *page,
 				    bool newly_allocated, bool wp_copy);
 
-extern 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);
-extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
-			      unsigned long dst_start,
-			      unsigned long len,
-			      atomic_t *mmap_changing);
-extern ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long dst_start,
-			      unsigned long len, atomic_t *mmap_changing);
+extern 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);
+extern ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm,
+				     unsigned long dst_start,
+				     unsigned long len,
+				     atomic_t *mmap_changing);
+extern ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long dst_start,
+				     unsigned long len, atomic_t *mmap_changing);
 extern int mwriteprotect_range(struct mm_struct *dst_mm,
 			       unsigned long start, unsigned long len,
 			       bool enable_wp, atomic_t *mmap_changing);