dax: dax_iomap_fault() needs to call iomap_end()

Currently iomap_end() doesn't do anything for DAX page faults for both ext2
and XFS.  ext2_iomap_end() just checks for a write underrun, and
xfs_file_iomap_end() checks to see if it needs to finish a delayed
allocation.  However, in the future iomap_end() calls might be needed to
make sure we have balanced allocations, locks, etc.  So, add calls to
iomap_end() with appropriate error handling to dax_iomap_fault().

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/dax.c b/fs/dax.c
index 77379546433ed458c62d694b2f0e625b1013e333..6edd89b3b69cfbb7904740f24beb659d283c1508 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1165,6 +1165,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
        struct iomap iomap = { 0 };
        unsigned flags = 0;
        int error, major = 0;
+       int locked_status = 0;
        void *entry;
 
        /*
@@ -1194,7 +1195,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
                goto unlock_entry;
        if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
                error = -EIO;           /* fs corruption? */
-               goto unlock_entry;
+               goto finish_iomap;
        }
 
        sector = dax_iomap_sector(&iomap, pos);
@@ -1216,13 +1217,15 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
                }
 
                if (error)
-                       goto unlock_entry;
+                       goto finish_iomap;
                if (!radix_tree_exceptional_entry(entry)) {
                        vmf->page = entry;
-                       return VM_FAULT_LOCKED;
+                       locked_status = VM_FAULT_LOCKED;
+               } else {
+                       vmf->entry = entry;
+                       locked_status = VM_FAULT_DAX_LOCKED;
                }
-               vmf->entry = entry;
-               return VM_FAULT_DAX_LOCKED;
+               goto finish_iomap;
        }
 
        switch (iomap.type) {
@@ -1237,8 +1240,10 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
                break;
        case IOMAP_UNWRITTEN:
        case IOMAP_HOLE:
-               if (!(vmf->flags & FAULT_FLAG_WRITE))
-                       return dax_load_hole(mapping, entry, vmf);
+               if (!(vmf->flags & FAULT_FLAG_WRITE)) {
+                       locked_status = dax_load_hole(mapping, entry, vmf);
+                       break;
+               }
                /*FALLTHRU*/
        default:
                WARN_ON_ONCE(1);
@@ -1246,14 +1251,30 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
                break;
        }
 
+ finish_iomap:
+       if (ops->iomap_end) {
+               if (error) {
+                       /* keep previous error */
+                       ops->iomap_end(inode, pos, PAGE_SIZE, 0, flags,
+                                       &iomap);
+               } else {
+                       error = ops->iomap_end(inode, pos, PAGE_SIZE,
+                                       PAGE_SIZE, flags, &iomap);
+               }
+       }
  unlock_entry:
-       put_locked_mapping_entry(mapping, vmf->pgoff, entry);
+       if (!locked_status || error)
+               put_locked_mapping_entry(mapping, vmf->pgoff, entry);
  out:
        if (error == -ENOMEM)
                return VM_FAULT_OOM | major;
        /* -EBUSY is fine, somebody else faulted on the same PTE */
        if (error < 0 && error != -EBUSY)
                return VM_FAULT_SIGBUS | major;
+       if (locked_status) {
+               WARN_ON_ONCE(error); /* -EBUSY from ops->iomap_end? */
+               return locked_status;
+       }
        return VM_FAULT_NOPAGE | major;
 }
 EXPORT_SYMBOL_GPL(dax_iomap_fault);