Merge tag 'drm-intel-next-fixes-2016-12-22' of git://anongit.freedesktop.org/git...

[mirror_ubuntu-artful-kernel.git] / fs / dax.c

diff --git a/fs/dax.c b/fs/dax.c
index cf7a20a5858b6f585713a6b914c6ede3346320e9..a8732fbed381a45bbce44fcdf0731ccfdc1a09ba 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -31,6 +31,7 @@
 #include <linux/vmstat.h>
 #include <linux/pfn_t.h>
 #include <linux/sizes.h>
+#include <linux/mmu_notifier.h>
 #include <linux/iomap.h>
 #include "internal.h"
 
@@ -614,6 +615,59 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
        return new_entry;
 }
 
+static inline unsigned long
+pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
+{
+       unsigned long address;
+
+       address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+       VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+       return address;
+}
+
+/* Walk all mappings of a given index of a file and writeprotect them */
+static void dax_mapping_entry_mkclean(struct address_space *mapping,
+                                     pgoff_t index, unsigned long pfn)
+{
+       struct vm_area_struct *vma;
+       pte_t *ptep;
+       pte_t pte;
+       spinlock_t *ptl;
+       bool changed;
+
+       i_mmap_lock_read(mapping);
+       vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
+               unsigned long address;
+
+               cond_resched();
+
+               if (!(vma->vm_flags & VM_SHARED))
+                       continue;
+
+               address = pgoff_address(index, vma);
+               changed = false;
+               if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
+                       continue;
+               if (pfn != pte_pfn(*ptep))
+                       goto unlock;
+               if (!pte_dirty(*ptep) && !pte_write(*ptep))
+                       goto unlock;
+
+               flush_cache_page(vma, address, pfn);
+               pte = ptep_clear_flush(vma, address, ptep);
+               pte = pte_wrprotect(pte);
+               pte = pte_mkclean(pte);
+               set_pte_at(vma->vm_mm, address, ptep, pte);
+               changed = true;
+unlock:
+               pte_unmap_unlock(ptep, ptl);
+
+               if (changed)
+                       mmu_notifier_invalidate_page(vma->vm_mm, address);
+       }
+       i_mmap_unlock_read(mapping);
+}
+
 static int dax_writeback_one(struct block_device *bdev,
                struct address_space *mapping, pgoff_t index, void *entry)
 {
@@ -687,7 +741,17 @@ static int dax_writeback_one(struct block_device *bdev,
                goto unmap;
        }
 
+       dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn));
        wb_cache_pmem(dax.addr, dax.size);
+       /*
+        * After we have flushed the cache, we can clear the dirty tag. There
+        * cannot be new dirty data in the pfn after the flush has completed as
+        * the pfn mappings are writeprotected and fault waits for mapping
+        * entry lock.
+        */
+       spin_lock_irq(&mapping->tree_lock);
+       radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
+       spin_unlock_irq(&mapping->tree_lock);
  unmap:
        dax_unmap_atomic(bdev, &dax);
        put_locked_mapping_entry(mapping, index, entry);