From: Demi Marie Obenour <demiobenour@gmail.com>
To: linux-btrfs@vger.kernel.org
Subject: Can the output of FIEMAP on BTRFS be used to check if a file and its reflink copy might have diverged?
Date: Sun, 21 Sep 2025 20:07:10 -0400 [thread overview]
Message-ID: <a697548b-cc40-4275-9da1-3b29351654f0@gmail.com> (raw)
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Wyng Backup (https://codeberg.org/tasket/wyng-backup) relies on FIEMAP
to determine which parts of a file have not changed since it was last
backed up. Specifically, the output of filefrag -v is passed to sort and
then to uniq, and differences between the outputs for the file and
the previous version (a reflink copy) determine what gets backed up.
Is this safe under BTRFS, or can it result in data loss due to data
not being backed up that should be? In other words, can it result
in data being considered unchanged when it really is?
--
Sincerely,
Demi Marie Obenour (she/her/hers)
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next reply other threads:[~2025-09-22 0:07 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-22 0:07 Demi Marie Obenour [this message]
2025-09-22 0:50 ` Can the output of FIEMAP on BTRFS be used to check if a file and its reflink copy might have diverged? Qu Wenruo
2025-09-22 18:24 ` Demi Marie Obenour
2025-09-22 21:38 ` Qu Wenruo
2025-09-22 16:48 ` Christoph Hellwig
2025-09-22 17:18 ` Demi Marie Obenour
2025-09-22 17:20 ` Christoph Hellwig
2025-09-22 17:30 ` Demi Marie Obenour
2025-09-22 17:31 ` Christoph Hellwig
2025-09-22 17:54 ` Demi Marie Obenour
2025-09-29 8:50 ` Christoph Hellwig
2025-09-29 23:56 ` Demi Marie Obenour
2025-09-30 1:34 ` Demi Marie Obenour
2025-10-03 7:45 ` Christoph Hellwig
2025-09-22 23:25 ` Chris Laprise
2025-09-29 8:49 ` Christoph Hellwig
2025-09-29 23:55 ` Demi Marie Obenour
2025-10-03 7:44 ` Christoph Hellwig
2025-10-04 1:09 ` Demi Marie Obenour
2025-10-04 1:43 ` Chris Laprise
2025-10-04 4:51 ` Christoph Hellwig
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