From: Filipe Manana <email@example.com> To: firstname.lastname@example.org, Filipe Manana <email@example.com>, linux-btrfs <firstname.lastname@example.org> Subject: Re: [PATCH 3/4] Btrfs: check if destination root is read-only for deduplication Date: Tue, 12 Feb 2019 17:59:41 +0000 Message-ID: <CAL3q7H7eNikSyf78cP+DpRAoYS0nRXNVZn6EvxXRBbYxSMasVw@mail.gmail.com> (raw) In-Reply-To: <CAL3q7H7T4Nercz9ZYtq_2yjpiPVjUX8+1xuvxnqnaDsip0bmYw@mail.gmail.com> On Thu, Jan 31, 2019 at 4:39 PM Filipe Manana <email@example.com> wrote: > > On Thu, Dec 13, 2018 at 4:08 PM David Sterba <firstname.lastname@example.org> wrote: > > > > On Wed, Dec 12, 2018 at 06:05:58PM +0000, email@example.com wrote: > > > From: Filipe Manana <firstname.lastname@example.org> > > > > > > Checking if the destination root is read-only was being performed only for > > > clone operations. Make deduplication check it as well, as it does not make > > > sense to not do it, even if it is an operation that does not change the > > > file contents (such as defrag for example, which checks first if the root > > > is read-only). > > > > And this is also change in user-visible behaviour of dedupe, so this > > needs to be verified if it's not breaking existing tools. > > Have you had the chance to do such verification? > > This actually conflicts with send. Send does not expect a root/tree to > change, and with dedupe on read-only roots happening > in parallel with send is going to cause all sorts of unexpected and > undesired problems... > > This is a problem introduced by dedupe ioctl when it landed, since > send existed for a longer time (when nothing else was > allowed to change read-only roots, including defrag). Another ping. This is a problem that has to be solved one way or another. Thanks. > > I understand it can break some applications, but adding other solution > such as preventing send and dedupe from running in parallel > (erroring out or block and wait for each other, etc) is going to be > really ugly. There's always the workaround for apps to set the > subvolume > to RW mode, do the dedupe, then switch it back to RO mode. > > Thanks.
next prev parent reply index Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-12-12 18:05 [PATCH 0/4] Btrfs: a few more cleanups and fixes for clone/deduplication fdmanana 2018-12-12 18:05 ` [PATCH 1/4] Btrfs: move duplicated nodatasum check into common reflink/dedupe helper fdmanana 2019-01-11 14:55 ` David Sterba 2018-12-12 18:05 ` [PATCH 2/4] Btrfs: use cross mount point check for cloning and deduplication fdmanana 2018-12-13 16:02 ` David Sterba 2019-01-11 14:38 ` David Sterba 2018-12-12 18:05 ` [PATCH 3/4] Btrfs: check if destination root is read-only for deduplication fdmanana 2018-12-13 16:07 ` David Sterba 2019-01-31 16:39 ` Filipe Manana 2019-01-31 16:44 ` Hugo Mills 2019-02-18 15:38 ` David Sterba 2019-02-18 16:55 ` Filipe Manana 2019-02-12 17:59 ` Filipe Manana [this message] 2019-02-20 16:41 ` Zygo Blaxell 2019-02-20 16:54 ` Filipe Manana 2019-02-20 17:17 ` Zygo Blaxell 2019-02-22 11:13 ` Filipe Manana 2019-02-22 17:25 ` David Sterba 2019-02-21 16:54 ` Zygo Blaxell 2019-02-18 16:01 ` David Sterba 2018-12-12 18:05 ` [PATCH 4/4] Btrfs: remove no longer needed range length checks " fdmanana 2018-12-13 12:20 ` Nikolay Borisov 2019-01-31 16:31 ` Filipe Manana 2019-02-12 17:58 ` Filipe Manana 2019-02-18 15:10 ` David Sterba 2018-12-13 12:19 ` [PATCH 0/4] Btrfs: a few more cleanups and fixes for clone/deduplication Nikolay Borisov
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