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From: Andrea Tomassetti <andrea.tomassetti-opensource@devo.com>
To: Coly Li <colyli@suse.de>
Cc: Kent Overstreet <kent.overstreet@gmail.com>,
	linux-bcache@vger.kernel.org
Subject: [RFC] Live resize of backing device
Date: Wed, 3 Aug 2022 12:05:55 +0200	[thread overview]
Message-ID: <CAHykVA5sgGooeRjM1EepCCpZqkvtQJ_=cY8hmjqe0oQ3FLDFnQ@mail.gmail.com> (raw)

Hi Coly,
In one of our previous emails you said that
> Currently bcache doesn’t support cache or backing device resize

I was investigating this point and I actually found a solution. I
briefly tested it and it seems to work fine.
Basically what I'm doing is:
  1. Check if there's any discrepancy between the nr of sectors
reported by the bcache backing device (holder) and the nr of sectors
reported by its parent (slave).
  2. If the number of sectors of the two devices are not the same,
then call set_capacity_and_notify on the bcache device.
  3. From user space, depending on the fs used, grow the fs with some
utility (e.g. xfs_growfs)

This works without any need of unmounting the mounted fs nor stopping
the bcache backing device.

 So my question is: am I missing something? Can this live resize cause
some problems (e.g. data loss)? Would it be useful if I send a patch
on this?

Kind regards,
Andrea

             reply	other threads:[~2022-08-03 10:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-03 10:05 Andrea Tomassetti [this message]
2022-08-04 14:32 ` [RFC] Live resize of backing device Coly Li
2022-08-05 19:38 ` Eric Wheeler
2022-09-06 13:22   ` Andrea Tomassetti
2022-09-08  8:32     ` Andrea Tomassetti
2022-09-19 11:42       ` Andrea Tomassetti
2022-09-19 12:16         ` Coly Li
2022-12-09  8:57           ` Andrea Tomassetti
2022-12-09  9:36             ` Coly Li
2022-12-30 10:40       ` Coly Li
2023-01-11 16:01         ` Andrea Tomassetti
2023-01-17 13:08           ` Error messages with kernel 6.1.[56] Pierre Juhen
2023-01-17 16:08             ` Coly Li
2023-01-17 16:18           ` [RFC] Live resize of backing device Coly Li
2023-01-25 10:07             ` Andrea Tomassetti
2023-01-25 17:59               ` Coly Li
2023-01-27 12:44                 ` Andrea Tomassetti
2023-01-27 22:40                   ` Eric Wheeler
2023-01-31 10:20                     ` Andrea Tomassetti
2023-02-02 17:18                   ` Coly Li
2023-02-02 20:48                     ` Eric Wheeler
2023-02-03  2:41                       ` Coly Li
2023-02-19  9:39                   ` Coly Li
2023-02-20  8:27                     ` mingzhe
2023-02-20 12:29                       ` Coly Li
2023-02-22  8:42                         ` Andrea Tomassetti
2023-02-27 22:08                       ` Eric Wheeler
2023-02-28  2:46                         ` mingzhe
2023-01-27  2:53               ` [RFC] Live resize of bcache " Eric Wheeler

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