From: David Sterba <dsterba@suse.cz>
To: Anand Jain <anand.jain@oracle.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>,
David Sterba <dsterba@suse.com>, Qu Wenru <wqu@suse.com>,
Linux BTRFS Mailinglist <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH v2 3/7] btrfs: handle allocation failure in strdup
Date: Fri, 15 Nov 2019 10:39:08 +0100 [thread overview]
Message-ID: <20191115093908.GN3001@suse.cz> (raw)
In-Reply-To: <3c492c97-0c41-a4b1-5687-6b9ccf40cf67@oracle.com>
On Thu, Nov 14, 2019 at 07:00:54PM +0800, Anand Jain wrote:
> On 13/11/19 6:27 PM, Johannes Thumshirn wrote:
> > Gracefully handle allocation failures in btrfs_close_one_device()'s
> > rcu_string_strdup() instead of crashing the machine.
> >
> > Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
> > ---
> > fs/btrfs/volumes.c | 22 ++++++++++++++--------
> > 1 file changed, 14 insertions(+), 8 deletions(-)
> >
> > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> > index 0a2a73907563..e5864ca3bb3b 100644
> > --- a/fs/btrfs/volumes.c
> > +++ b/fs/btrfs/volumes.c
> > @@ -1064,7 +1064,7 @@ static void btrfs_close_bdev(struct btrfs_device *device)
> > static int btrfs_close_one_device(struct btrfs_device *device)
> > {
> > struct btrfs_fs_devices *fs_devices = device->fs_devices;
> > - struct btrfs_device *new_device;
> > + struct btrfs_device *new_device = NULL;
> > struct rcu_string *name;
> >
> > new_device = btrfs_alloc_device(NULL, &device->devid,
> > @@ -1072,6 +1072,15 @@ static int btrfs_close_one_device(struct btrfs_device *device)
> > if (IS_ERR(new_device))
> > goto err_close_device;
> >
> > + /* Safe because we are under uuid_mutex */
> > + if (device->name) {
> > + name = rcu_string_strdup(device->name->str, GFP_NOFS);
> > + if (!name)
> > + goto err_free_device;
> > +
> > + rcu_assign_pointer(new_device->name, name);
> > + }
> > +
>
> Any idea why do we need to strdup() at all to close a device?
It shouldn't be needed but that's how it got implemented since the
beginning in e4404d6e8da678d852. The device on close is duplicated, so
has to be the name.
next prev parent reply other threads:[~2019-11-15 9:39 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-13 10:27 [PATCH v2 0/7] remove BUG_ON()s in btrfs_close_one_device() Johannes Thumshirn
2019-11-13 10:27 ` [PATCH v2 1/7] btrfs: decrement number of open devices after closing the device not before Johannes Thumshirn
2019-11-13 10:27 ` [PATCH v2 2/7] btrfs: handle device allocation failure in btrfs_close_one_device() Johannes Thumshirn
2019-11-13 14:58 ` David Sterba
2019-11-14 8:48 ` Johannes Thumshirn
2019-11-14 10:56 ` Anand Jain
2019-11-14 12:03 ` Johannes Thumshirn
2019-11-14 13:02 ` Johannes Thumshirn
2019-11-13 10:27 ` [PATCH v2 3/7] btrfs: handle allocation failure in strdup Johannes Thumshirn
2019-11-14 11:00 ` Anand Jain
2019-11-15 9:39 ` David Sterba [this message]
2019-11-15 21:11 ` Nikolay Borisov
2019-11-13 10:27 ` [PATCH v2 4/7] btrfs: handle error return of close_fs_devices() Johannes Thumshirn
2019-11-13 15:00 ` David Sterba
2019-11-14 8:15 ` Johannes Thumshirn
2019-11-13 10:27 ` [PATCH v2 5/7] btrfs: remove final BUG_ON() in close_fs_devices() Johannes Thumshirn
2019-11-13 15:02 ` David Sterba
2019-11-14 9:01 ` Johannes Thumshirn
2019-11-13 10:27 ` [PATCH v2 6/7] btrfs: change btrfs_fs_devices::seeing to bool Johannes Thumshirn
2019-11-14 11:04 ` Anand Jain
2019-11-13 10:27 ` [PATCH v2 7/7] btrfs: change btrfs_fs_devices::rotating " Johannes Thumshirn
2019-11-14 11:05 ` Anand Jain
2019-11-13 11:56 ` [PATCH v2 0/7] remove BUG_ON()s in btrfs_close_one_device() Qu Wenruo
2019-11-13 15:05 ` David Sterba
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