From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753370Ab2H2NO5 (ORCPT ); Wed, 29 Aug 2012 09:14:57 -0400 Received: from [66.192.166.38] ([66.192.166.38]:36965 "EHLO hancock.steeleye.com" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752255Ab2H2NO4 (ORCPT ); Wed, 29 Aug 2012 09:14:56 -0400 Date: Wed, 29 Aug 2012 08:41:02 -0400 From: paul.clements@steeleye.com To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] [RESEND] add discard support to nbd Message-ID: <503e0dde.ssYktQsJ5nYlhlQB%paul.clements@steeleye.com> User-Agent: nail 11.25 7/29/05 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Description: This patch adds discard support to nbd. When the nbd client system receives a discard request, this will be passed along to the nbd server system, where the nbd-server will respond by performing: fallocate(.. FALLOC_FL_PUNCH_HOLE ..) To punch a hole in the backend storage, which is no longer needed. Signed-off-by: Paul Clements --- diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index c544bb4..a014169 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -98,6 +98,7 @@ static const char *nbdcmd_to_ascii(int cmd) case NBD_CMD_READ: return "read"; case NBD_CMD_WRITE: return "write"; case NBD_CMD_DISC: return "disconnect"; + case NBD_CMD_TRIM: return "trim/discard"; } return "invalid"; } @@ -461,7 +462,11 @@ static void nbd_handle_req(struct nbd_device *nbd, struct request *req) nbd_cmd(req) = NBD_CMD_READ; if (rq_data_dir(req) == WRITE) { - nbd_cmd(req) = NBD_CMD_WRITE; + if ((req->cmd_flags & REQ_DISCARD)) { + WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM)); + nbd_cmd(req) = NBD_CMD_TRIM; + } else + nbd_cmd(req) = NBD_CMD_WRITE; if (nbd->flags & NBD_FLAG_READ_ONLY) { dev_err(disk_to_dev(nbd->disk), "Write on read-only\n"); @@ -667,6 +672,10 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, mutex_unlock(&nbd->tx_lock); + if (nbd->flags & NBD_FLAG_SEND_TRIM) + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, + nbd->disk->queue); + thread = kthread_create(nbd_thread, nbd, nbd->disk->disk_name); if (IS_ERR(thread)) { mutex_lock(&nbd->tx_lock); @@ -684,6 +693,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, nbd->file = NULL; nbd_clear_que(nbd); dev_warn(disk_to_dev(nbd->disk), "queue cleared\n"); + queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); if (file) fput(file); nbd->bytesize = 0; @@ -802,6 +812,9 @@ static int __init nbd_init(void) * Tell the block layer that we are not a rotational device */ queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue); + disk->queue->limits.discard_granularity = 512; + disk->queue->limits.max_discard_sectors = UINT_MAX; + disk->queue->limits.discard_zeroes_data = 0; } if (register_blkdev(NBD_MAJOR, "nbd")) { diff --git a/include/linux/nbd.h b/include/linux/nbd.h index bb349be..3b49a63 100644 --- a/include/linux/nbd.h +++ b/include/linux/nbd.h @@ -32,12 +32,16 @@ enum { NBD_CMD_READ = 0, NBD_CMD_WRITE = 1, - NBD_CMD_DISC = 2 + NBD_CMD_DISC = 2, + /* there is a gap here to match userspace */ + NBD_CMD_TRIM = 4 }; /* values for flags field */ #define NBD_FLAG_HAS_FLAGS (1 << 0) #define NBD_FLAG_READ_ONLY (1 << 1) +/* there is a gap here to match userspace */ +#define NBD_FLAG_SEND_TRIM (1 << 5) /* send trim/discard */ #define nbd_cmd(req) ((req)->cmd[0])