From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44159) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fk9oW-0003Og-Br for qemu-devel@nongnu.org; Mon, 30 Jul 2018 11:10:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fk9oV-0008Nr-Fg for qemu-devel@nongnu.org; Mon, 30 Jul 2018 11:10:24 -0400 From: Kevin Wolf Date: Mon, 30 Jul 2018 17:09:54 +0200 Message-Id: <20180730150958.14607-10-kwolf@redhat.com> In-Reply-To: <20180730150958.14607-1-kwolf@redhat.com> References: <20180730150958.14607-1-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 09/13] block: Fix documentation for BDRV_REQ_MAY_UNMAP List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org BDRV_REQ_MAY_UNMAP in a write_zeroes request does not only allow the driver to unmap the blocks, but it actively requests that the blocks be unmapped afterwards if at all possible. Signed-off-by: Kevin Wolf --- include/block/block.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/include/block/block.h b/include/block/block.h index f85e3a6ed3..4e0871aaf9 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -43,11 +43,12 @@ typedef struct BlockFragInfo { typedef enum { BDRV_REQ_COPY_ON_READ = 0x1, BDRV_REQ_ZERO_WRITE = 0x2, - /* The BDRV_REQ_MAY_UNMAP flag is used to indicate that the block driver - * is allowed to optimize a write zeroes request by unmapping (discarding) - * blocks if it is guaranteed that the result will read back as - * zeroes. The flag is only passed to the driver if the block device is - * opened with BDRV_O_UNMAP. + + /* + * The BDRV_REQ_MAY_UNMAP flag is used in write_zeroes requests to indicate + * that the block driver should unmap (discard) blocks if it is guaranteed + * that the result will read back as zeroes. The flag is only passed to the + * driver if the block device is opened with BDRV_O_UNMAP. */ BDRV_REQ_MAY_UNMAP = 0x4, -- 2.13.6