1 files changed, 29 insertions, 13 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 3d4df44e4221..75572b5f2374 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -612,6 +612,19 @@ void __lock_page_nosync(struct page *page)
                                                         TASK_UNINTERRUPTIBLE);
 }
 
+int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
+                         unsigned int flags)
+{
+        if (!(flags & FAULT_FLAG_ALLOW_RETRY)) {
+                __lock_page(page);
+                return 1;
+        } else {
+                up_read(&mm->mmap_sem);
+                wait_on_page_locked(page);
+                return 0;
+        }
+}
+
 /**
  * find_get_page - find and get a page reference
  * @mapping: the address_space to search
@@ -1539,25 +1552,28 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
                  * waiting for the lock.
                  */
                 do_async_mmap_readahead(vma, ra, file, page, offset);
-                lock_page(page);
-
-                /* Did it get truncated? */
-                if (unlikely(page->mapping != mapping)) {
-                        unlock_page(page);
-                        put_page(page);
-                        goto no_cached_page;
-                }
         } else {
                 /* No page in the page cache at all */
                 do_sync_mmap_readahead(vma, ra, file, offset);
                 count_vm_event(PGMAJFAULT);
                 ret = VM_FAULT_MAJOR;
 retry_find:
-                page = find_lock_page(mapping, offset);
+                page = find_get_page(mapping, offset);
                 if (!page)
                         goto no_cached_page;
         }
 
+        if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags))
+                return ret | VM_FAULT_RETRY;
+
+        /* Did it get truncated? */
+        if (unlikely(page->mapping != mapping)) {
+                unlock_page(page);
+                put_page(page);
+                goto retry_find;
+        }
+        VM_BUG_ON(page->index != offset);
+
         /*
          * We have a locked page in the page cache, now we need to check
          * that it's up-to-date. If not, it is going to be due to an error.
@@ -2177,12 +2193,12 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
         }
 
         if (written > 0) {
-                loff_t end = pos + written;
-                if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
-                        i_size_write(inode,  end);
+                pos += written;
+                if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
+                        i_size_write(inode, pos);
                         mark_inode_dirty(inode);
                 }
-                *ppos = end;
+                *ppos = pos;
         }
 out:
         return written;