[PATCH 28/35] mm, dmemfs: support huge_fault() for dmemfs

[yulei . kernel]

From: Yulei Zhang <yuleixzh...@tencent.com>

Introduce __dmemfs_huge_fault() to handle 1G huge pud for dmemfs.

Signed-off-by: Chen Zhuo <sagazc...@tencent.com>
Signed-off-by: Yulei Zhang <yuleixzh...@tencent.com>
---
 fs/dmemfs/inode.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/fs/dmemfs/inode.c b/fs/dmemfs/inode.c
index 53a9bf214e0d..027428a7f7a0 100644
--- a/fs/dmemfs/inode.c
+++ b/fs/dmemfs/inode.c
@@ -522,6 +522,43 @@ static vm_fault_t  __dmemfs_pmd_fault(struct vm_fault *vmf)
        return ret;
 }
 
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static vm_fault_t __dmemfs_huge_fault(struct vm_fault *vmf)
+{
+       struct vm_area_struct *vma = vmf->vma;
+       unsigned long pud_addr = vmf->address & PUD_MASK;
+       struct inode *inode = file_inode(vma->vm_file);
+       void *entry;
+       phys_addr_t phys;
+       pfn_t pfn;
+       int ret;
+
+       if (dmem_page_size(inode) < PUD_SIZE)
+               return VM_FAULT_FALLBACK;
+
+       WARN_ON(pud_addr < vma->vm_start ||
+               vma->vm_end < pud_addr + PUD_SIZE);
+
+       entry = radix_get_create_entry(vma, pud_addr, inode,
+                                      linear_page_index(vma, pud_addr));
+       if (IS_ERR(entry))
+               return (PTR_ERR(entry) == -ENOMEM) ?
+                       VM_FAULT_OOM : VM_FAULT_SIGBUS;
+
+       phys = dmem_entry_to_addr(inode, entry);
+       pfn = phys_to_pfn_t(phys, PFN_DMEM);
+       ret = vmf_insert_pfn_pud(vmf, pfn, !!(vma->vm_flags & VM_WRITE));
+
+       radix_put_entry();
+       return ret;
+}
+#else
+static vm_fault_t __dmemfs_huge_fault(struct vm_fault *vmf)
+{
+       return VM_FAULT_FALLBACK;
+}
+#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+
 static vm_fault_t dmemfs_huge_fault(struct vm_fault *vmf, enum page_entry_size 
pe_size)
 {
        int ret;
@@ -533,6 +570,9 @@ static vm_fault_t dmemfs_huge_fault(struct vm_fault *vmf, 
enum page_entry_size p
        case PE_SIZE_PMD:
                ret = __dmemfs_pmd_fault(vmf);
                break;
+       case PE_SIZE_PUD:
+               ret = __dmemfs_huge_fault(vmf);
+               break;
        default:
                ret = VM_FAULT_SIGBUS;
        }
-- 
2.28.0