Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[uclinux-h8/linux.git] / fs / dax.c

diff --git a/fs/dax.c b/fs/dax.c
index 37a0c48..c3e21cc 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -311,14 +311,21 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
  out:
        i_mmap_unlock_read(mapping);
 
-       if (bh->b_end_io)
-               bh->b_end_io(bh, 1);
-
        return error;
 }
 
-static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
-                       get_block_t get_block)
+/**
+ * __dax_fault - handle a page fault on a DAX file
+ * @vma: The virtual memory area where the fault occurred
+ * @vmf: The description of the fault
+ * @get_block: The filesystem method used to translate file offsets to blocks
+ *
+ * When a page fault occurs, filesystems may call this helper in their
+ * fault handler for DAX files. __dax_fault() assumes the caller has done all
+ * the necessary locking for the page fault to proceed successfully.
+ */
+int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
+                       get_block_t get_block, dax_iodone_t complete_unwritten)
 {
        struct file *file = vma->vm_file;
        struct address_space *mapping = file->f_mapping;
@@ -419,7 +426,19 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
                page_cache_release(page);
        }
 
+       /*
+        * If we successfully insert the new mapping over an unwritten extent,
+        * we need to ensure we convert the unwritten extent. If there is an
+        * error inserting the mapping, the filesystem needs to leave it as
+        * unwritten to prevent exposure of the stale underlying data to
+        * userspace, but we still need to call the completion function so
+        * the private resources on the mapping buffer can be released. We
+        * indicate what the callback should do via the uptodate variable, same
+        * as for normal BH based IO completions.
+        */
        error = dax_insert_mapping(inode, &bh, vma, vmf);
+       if (buffer_unwritten(&bh))
+               complete_unwritten(&bh, !error);
 
  out:
        if (error == -ENOMEM)
@@ -436,6 +455,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
        }
        goto out;
 }
+EXPORT_SYMBOL(__dax_fault);
 
 /**
  * dax_fault - handle a page fault on a DAX file
@@ -447,7 +467,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
  * fault handler for DAX files.
  */
 int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
-                       get_block_t get_block)
+             get_block_t get_block, dax_iodone_t complete_unwritten)
 {
        int result;
        struct super_block *sb = file_inode(vma->vm_file)->i_sb;
@@ -456,7 +476,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
                sb_start_pagefault(sb);
                file_update_time(vma->vm_file);
        }
-       result = do_dax_fault(vma, vmf, get_block);
+       result = __dax_fault(vma, vmf, get_block, complete_unwritten);
        if (vmf->flags & FAULT_FLAG_WRITE)
                sb_end_pagefault(sb);