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Diffstat (limited to 'fs/dax.c')
-rw-r--r--fs/dax.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/fs/dax.c b/fs/dax.c
index c3e21ccfc358..a7f77e1fa18c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -319,6 +319,12 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
* @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
+ * @complete_unwritten: The filesystem method used to convert unwritten blocks
+ * to written so the data written to them is exposed. This is required for
+ * required by write faults for filesystems that will return unwritten
+ * extent mappings from @get_block, but it is optional for reads as
+ * dax_insert_mapping() will always zero unwritten blocks. If the fs does
+ * not support unwritten extents, the it should pass NULL.
*
* 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
@@ -437,8 +443,12 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
* as for normal BH based IO completions.
*/
error = dax_insert_mapping(inode, &bh, vma, vmf);
- if (buffer_unwritten(&bh))
- complete_unwritten(&bh, !error);
+ if (buffer_unwritten(&bh)) {
+ if (complete_unwritten)
+ complete_unwritten(&bh, !error);
+ else
+ WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE));
+ }
out:
if (error == -ENOMEM)