1 files changed, 22 insertions, 13 deletions

diff --git a/fs/dax.c b/fs/dax.c
index de622d4282a6..85abd741253d 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -373,6 +373,22 @@ restart:
                 }
                 spin_lock_irq(&mapping->tree_lock);
 
+                if (!entry) {
+                        /*
+                         * We needed to drop the page_tree lock while calling
+                         * radix_tree_preload() and we didn't have an entry to
+                         * lock.  See if another thread inserted an entry at
+                         * our index during this time.
+                         */
+                        entry = __radix_tree_lookup(&mapping->page_tree, index,
+                                        NULL, &slot);
+                        if (entry) {
+                                radix_tree_preload_end();
+                                spin_unlock_irq(&mapping->tree_lock);
+                                goto restart;
+                        }
+                }
+
                 if (pmd_downgrade) {
                         radix_tree_delete(&mapping->page_tree, index);
                         mapping->nrexceptional--;
@@ -388,19 +404,12 @@ restart:
                 if (err) {
                         spin_unlock_irq(&mapping->tree_lock);
                         /*
-                         * Someone already created the entry?  This is a
-                         * normal failure when inserting PMDs in a range
-                         * that already contains PTEs.  In that case we want
-                         * to return -EEXIST immediately.
-                         */
-                        if (err == -EEXIST && !(size_flag & RADIX_DAX_PMD))
-                                goto restart;
-                        /*
-                         * Our insertion of a DAX PMD entry failed, most
-                         * likely because it collided with a PTE sized entry
-                         * at a different index in the PMD range.  We haven't
-                         * inserted anything into the radix tree and have no
-                         * waiters to wake.
+                         * Our insertion of a DAX entry failed, most likely
+                         * because we were inserting a PMD entry and it
+                         * collided with a PTE sized entry at a different
+                         * index in the PMD range.  We haven't inserted
+                         * anything into the radix tree and have no waiters to
+                         * wake.
                          */
                         return ERR_PTR(err);
                 }