@@ -57,11 +57,15 @@ static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
PAGE_CACHE_SIZE - offset, write_bytes);
struct page *page = prepared_pages[pg];
again:
- if (unlikely(iov_iter_fault_in_readable(i, count)))
- return -EFAULT;
-
- /* Copy data from userspace to the current page */
- copied = iov_iter_copy_from_user(page, i, offset, count);
+ /*
+ * Copy data from userspace to the current page
+ *
+ * Disable pagefault to avoid recursive lock since
+ * the pages are already locked
+ */
+ pagefault_disable();
+ copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
+ pagefault_enable();
/* Flush processor's dcache for this page */
flush_dcache_page(page);
@@ -974,6 +978,15 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
if (ret)
goto out;
+ /*
+ * fault pages before locking them in prepare_pages
+ * to avoid recursive lock
+ */
+ if (unlikely(iov_iter_fault_in_readable(&i, write_bytes))) {
+ ret = -EFAULT;
+ goto out;
+ }
+
ret = prepare_pages(root, file, pages, num_pages,
pos, first_index, last_index,
write_bytes);