From: Stefan Hajnoczi <stefa...@redhat.com>

Add DAX mmap() support.

Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
 fs/fuse/file.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index edbb11ca735e..a053bcb9498d 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2576,10 +2576,15 @@ static const struct vm_operations_struct 
fuse_file_vm_ops = {
        .page_mkwrite   = fuse_page_mkwrite,
 };
 
+static int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma);
 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
        struct fuse_file *ff = file->private_data;
 
+       /* DAX mmap is superior to direct_io mmap */
+       if (IS_DAX(file_inode(file)))
+               return fuse_dax_mmap(file, vma);
+
        if (ff->open_flags & FOPEN_DIRECT_IO) {
                /* Can't provide the coherency needed for MAP_SHARED */
                if (vma->vm_flags & VM_MAYSHARE)
@@ -2611,9 +2616,65 @@ static ssize_t fuse_file_splice_read(struct file *in, 
loff_t *ppos,
 
 }
 
+static int __fuse_dax_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
+                           bool write)
+{
+       vm_fault_t ret;
+       struct inode *inode = file_inode(vmf->vma->vm_file);
+       struct super_block *sb = inode->i_sb;
+       pfn_t pfn;
+
+       if (write)
+               sb_start_pagefault(sb);
+
+       /* TODO inode semaphore to protect faults vs truncate */
+
+       ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL, &fuse_iomap_ops);
+
+       if (ret & VM_FAULT_NEEDDSYNC)
+               ret = dax_finish_sync_fault(vmf, pe_size, pfn);
+
+       if (write)
+               sb_end_pagefault(sb);
+
+       return ret;
+}
+
+static vm_fault_t fuse_dax_fault(struct vm_fault *vmf)
+{
+       return __fuse_dax_fault(vmf, PE_SIZE_PTE,
+                               vmf->flags & FAULT_FLAG_WRITE);
+}
+
+static vm_fault_t fuse_dax_huge_fault(struct vm_fault *vmf,
+                              enum page_entry_size pe_size)
+{
+       return __fuse_dax_fault(vmf, pe_size, vmf->flags & FAULT_FLAG_WRITE);
+}
+
+static vm_fault_t fuse_dax_page_mkwrite(struct vm_fault *vmf)
+{
+       return __fuse_dax_fault(vmf, PE_SIZE_PTE, true);
+}
+
+static vm_fault_t fuse_dax_pfn_mkwrite(struct vm_fault *vmf)
+{
+       return __fuse_dax_fault(vmf, PE_SIZE_PTE, true);
+}
+
+static const struct vm_operations_struct fuse_dax_vm_ops = {
+       .fault          = fuse_dax_fault,
+       .huge_fault     = fuse_dax_huge_fault,
+       .page_mkwrite   = fuse_dax_page_mkwrite,
+       .pfn_mkwrite    = fuse_dax_pfn_mkwrite,
+};
+
 static int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma)
 {
-       return -EINVAL; /* TODO */
+       file_accessed(file);
+       vma->vm_ops = &fuse_dax_vm_ops;
+       vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
+       return 0;
 }
 
 static int convert_fuse_file_lock(struct fuse_conn *fc,
@@ -3622,6 +3683,7 @@ static const struct file_operations fuse_file_operations 
= {
        .release        = fuse_release,
        .fsync          = fuse_fsync,
        .lock           = fuse_file_lock,
+       .get_unmapped_area = thp_get_unmapped_area,
        .flock          = fuse_file_flock,
        .splice_read    = fuse_file_splice_read,
        .splice_write   = iter_file_splice_write,
-- 
2.20.1

Reply via email to