From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:40690 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932261AbaJ2K4V (ORCPT ); Wed, 29 Oct 2014 06:56:21 -0400 Message-ID: <5450C7CA.5010005@oracle.com> Date: Wed, 29 Oct 2014 18:56:10 +0800 From: Anand Jain MIME-Version: 1.0 To: Gui Hecheng CC: linux-btrfs@vger.kernel.org, David Sterba Subject: Re: [PATCH] btrfs-progs: fix dev stats error output related to replace handle References: <1414029371-6765-1-git-send-email-guihc.fnst@cn.fujitsu.com> In-Reply-To: <1414029371-6765-1-git-send-email-guihc.fnst@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi Gui, We don't need this patch. Actually you should back out this patch to get this correct. [PATCH] btrfs-progs: do a separate probe for _transient_ replacing device OR apply. this [PATCH] revert btrfs-progs: do a separate probe for _transient_ replacing device Try it out. Lets know. Thanks On 10/23/14 09:56, Gui Hecheng wrote: > Steps to reproduce: > # mkfs.btrfs -f /dev/sdb7 > # mount /dev/sdb7 /mnt > # btrfs dev stats /dev/sdb7 > output: > [/dev/sdb7].write_io_errs 0 > [/dev/sdb7].read_io_errs 0 > [/dev/sdb7].flush_io_errs 0 > [/dev/sdb7].corruption_errs 0 > [/dev/sdb7].generation_errs 0 > * ERROR: ioctl(BTRFS_IOC_GET_DEV_STATS) on failed: No such device > > while the following cmd: > # btrfs dev stats /mnt > yields the right thing: > [/dev/sdb7].write_io_errs 0 > [/dev/sdb7].read_io_errs 0 > [/dev/sdb7].flush_io_errs 0 > [/dev/sdb7].corruption_errs 0 > [/dev/sdb7].generation_errs 0 > > This is caused by commit: > commit d0588bfa479409b2a0f6243f894338a01a56221a > btrfs-progs: do a separate probe for transient replacing device > > The above commit trys to handle the fi show problem with device under > replacing, but it changes the @get_fs_info() logic which annoys dev stats. > For @get_fs_info(): > o If the passed in @path is a mount point, then the @get_device_info() to > probe the replacing device will be glad to accept the device index > var @i as its init value 0 and the following i++ correctly sets @i > to 1 as the start of all devices in btrfs. > o If @path is a block device, then the problem comes... > The device index @i is set to devid of the block device passed in, > and the @get_device_info() will be forced to accept the devid unwillingly. > Then the following i++ do the evil of skip the block device desired and an > empty piece is handled next which causes the ERROR above. > > To fix this problem, let's just pass 0 to the @get_device_info() explicitly, > and set the index @i to 1 if a mount point is passed in. > > Under my own test, this will not affect the original fix of the fi show > problem with device under replacing. > > Signed-off-by: Gui Hecheng > --- > utils.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/utils.c b/utils.c > index f10c178..0ba2b26 100644 > --- a/utils.c > +++ b/utils.c > @@ -1881,12 +1881,15 @@ int get_fs_info(char *path, struct btrfs_ioctl_fs_info_args *fi_args, > } > > /* get the replace target device if it is there */ > - ret = get_device_info(fd, i, &di_args[ndevs]); > + ret = get_device_info(fd, 0, &di_args[ndevs]); > if (!ret) { > ndevs++; > fi_args->num_devices++; > } > - i++; > + > + /* if a mount point is passed in, start from devid 1 */ > + if (fi_args->num_devices != 1) > + i = 1; > > for (; i <= fi_args->max_id; ++i) { > BUG_ON(ndevs >= fi_args->num_devices); >