From 2e5ab5f379f96a6207c45be40c357ebb1beb8ef3 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Mon, 17 Aug 2015 10:31:49 +0800 Subject: block: loop: prepare for supporing direct IO This patches provides one interface for enabling direct IO from user space: - userspace(such as losetup) can pass 'file' which is opened/fcntl as O_DIRECT Also __loop_update_dio() is introduced to check if direct I/O can be used on current loop setting. The last big change is to introduce LO_FLAGS_DIRECT_IO flag for userspace to know if direct IO is used to access backing file. Cc: linux-api@vger.kernel.org Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- include/uapi/linux/loop.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/uapi/linux/loop.h') diff --git a/include/uapi/linux/loop.h b/include/uapi/linux/loop.h index e0cecd2eabdc..949851ce681f 100644 --- a/include/uapi/linux/loop.h +++ b/include/uapi/linux/loop.h @@ -21,6 +21,7 @@ enum { LO_FLAGS_READ_ONLY = 1, LO_FLAGS_AUTOCLEAR = 4, LO_FLAGS_PARTSCAN = 8, + LO_FLAGS_DIRECT_IO = 16, }; #include /* for __kernel_old_dev_t */ -- cgit v1.2.3