mm/userfaultfd: Moduarlize uffd_writeprotect() for memory types

Each memory type that treats the writeprotect differently has its own
implementation so that each one can do what it needs without injecting
checks on other types unnecessarily.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 114f9257d240f97dbbf36ff205d939b84efc327d..6f919008bddea8d5fa44d97cbaf56a9f3260396c 100644 (file)
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -116,6 +116,7 @@ struct uffd_info {
 }
 
 /* VMA userfaultfd operations */
+int uffd_writeprotect(struct uffd_info *info);
 ssize_t uffd_failed_do_unlock(struct userfaultfd_ctx *ctx,
                struct vm_area_struct *dst, struct folio *folio,
                unsigned long src_addr);
@@ -125,6 +126,7 @@ struct vm_uffd_ops {
        int (*zeropage)(struct uffd_info *info);
        int (*cont)(struct uffd_info *info);
        int (*poison)(struct uffd_info *info);
+       int (*writeprotect)(struct uffd_info *info);
        /* Required features below */
        ssize_t (*is_dst_valid)(struct vm_area_struct *dst_vma,
                                unsigned long dst_start, unsigned long len);

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 97b402762921d3c33562b680f5197a19d400fc8e..72daaf8d06e1ead02a0e8ef6327a87b1a293216e 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5538,6 +5538,7 @@ static const struct vm_uffd_ops hugetlb_uffd_ops = {
        .zeropage               =       NULL,
        .cont                   =       hugetlb_mfill_pte_continue,
        .poison                 =       hugetlb_mfill_pte_poison,
+       .writeprotect           =       uffd_writeprotect,
        .is_dst_valid           =       hugetlb_is_dst_valid,
        .increment              =       hugetlb_mfill_size,
        .failed_do_unlock       =       hugetlb_failed_do_unlock,

diff --git a/mm/shmem.c b/mm/shmem.c
index 165b428a661e0845c39ea51565317e1a3ab51f3b..3ddf7f42e1fa9b5b84178804df7f21c597bef539 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5273,6 +5273,7 @@ static const struct vm_uffd_ops shmem_uffd_ops = {
        .zeropage               =       shmem_mfill_atomic_pte_zeropage,
        .cont                   =       shmem_mfill_atomic_pte_continue,
        .poison                 =       mfill_atomic_pte_poison,
+       .writeprotect           =       uffd_writeprotect,
        .is_dst_valid           =       shmem_is_dst_valid,
        .increment              =       mfill_size,
        .failed_do_unlock       =       uffd_failed_do_unlock,

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 1bdccadcaeb3545f16a1cf4677d8a5ac5c1d6ce8..f7c5b40f3e0571d6710eb1297e3be730c0de7984 100644 (file)
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -475,6 +475,7 @@ static const struct vm_uffd_ops default_uffd_ops = {
        .zeropage               = mfill_atomic_pte_zeropage,
        .cont                   = NULL,
        .poison                 = mfill_atomic_pte_poison,
+       .writeprotect           = uffd_writeprotect,
        .is_dst_valid           = uffd_def_is_dst_valid,
        .increment              = mfill_size,
        .failed_do_unlock       = uffd_failed_do_unlock,
@@ -784,7 +785,7 @@ long uffd_wp_range(struct vm_area_struct *dst_vma,
        return ret;
 }
 
-static int uffd_writeprotect(struct uffd_info *info)
+int uffd_writeprotect(struct uffd_info *info)
 {
        long err;
        struct vm_area_struct *dst_vma;
@@ -843,7 +844,11 @@ int mwriteprotect_range(struct userfaultfd_ctx *ctx, unsigned long start,
 
        err = -ENOENT;
        for_each_vma_range(vmi, info.dst_vma, start + len) {
-               err = uffd_writeprotect(&info);
+               info.uffd_ops = vma_get_uffd_ops(info.dst_vma);
+               err = -EINVAL;
+               if (!info.uffd_ops || !info.uffd_ops->writeprotect)
+                       break;
+               err = info.uffd_ops->writeprotect(&info);
                if (err)
                        break;
        }