From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f196.google.com ([209.85.215.196]:42661 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727530AbeIHBsq (ORCPT ); Fri, 7 Sep 2018 21:48:46 -0400 Received: by mail-pg1-f196.google.com with SMTP id y4-v6so7546705pgp.9 for ; Fri, 07 Sep 2018 14:06:02 -0700 (PDT) Date: Fri, 7 Sep 2018 14:06:01 -0700 From: Omar Sandoval To: David Sterba Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH 05/11] btrfs: dev-replace: avoid useless lock on error handling path Message-ID: <20180907210601.GH29245@vader> References: <41a1cc8519061dde7a7cbf2139f672d433a5cfbd.1536331604.git.dsterba@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <41a1cc8519061dde7a7cbf2139f672d433a5cfbd.1536331604.git.dsterba@suse.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Sep 07, 2018 at 04:55:11PM +0200, David Sterba wrote: > The exit sequence in btrfs_dev_replace_start does not allow to simply > add a label to the right place so the error handling after starting > transaction failure jumps there. Currently there's a lock that pairs > with the unlock in the section, which is unnecessary and only raises > questions. Add a variable to track the locking status and avoid the > extra locking. Reviewed-by: Omar Sandoval > Signed-off-by: David Sterba > --- > fs/btrfs/dev-replace.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c > index 8b512dddf727..0a49843b2ee6 100644 > --- a/fs/btrfs/dev-replace.c > +++ b/fs/btrfs/dev-replace.c > @@ -400,6 +400,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > int ret; > struct btrfs_device *tgt_device = NULL; > struct btrfs_device *src_device = NULL; > + bool need_unlock; > > ret = btrfs_find_device_by_devspec(fs_info, srcdevid, > srcdev_name, &src_device); > @@ -424,6 +425,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > return PTR_ERR(trans); > } > > + need_unlock = true; > btrfs_dev_replace_write_lock(dev_replace); > switch (dev_replace->replace_state) { > case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED: > @@ -462,6 +464,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > atomic64_set(&dev_replace->num_write_errors, 0); > atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0); > btrfs_dev_replace_write_unlock(dev_replace); > + need_unlock = false; > > ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device); > if (ret) > @@ -473,7 +476,6 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > trans = btrfs_start_transaction(root, 0); > if (IS_ERR(trans)) { > ret = PTR_ERR(trans); > - btrfs_dev_replace_write_lock(dev_replace); > goto leave; > } > > @@ -497,7 +499,8 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > leave: > dev_replace->srcdev = NULL; > dev_replace->tgtdev = NULL; > - btrfs_dev_replace_write_unlock(dev_replace); > + if (need_unlock) > + btrfs_dev_replace_write_unlock(dev_replace); > btrfs_destroy_dev_replace_tgtdev(tgt_device); > return ret; > } > -- > 2.18.0 >