Re: Defrag operations sometimes don't work.

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On Sat, Jul 11, 2015 at 4:12 AM, Martin Steigerwald <martin@xxxxxxxxxxxx> wrote:
> Always do "sync" after a "btrfs fi defrag" and before measuring with
> "filefrag". The kernel may not have written everything. I have seen this
> repeatedly that the extent count drops further after a "sync", following
> "btrfs fi defrag".

First of all, thank you for your help. This fixed the problem for
defragging individual files.

I'm now seeing that recursive defragging doesn't work the way I expect. Running

$ btrfs fi defrag -r /path/to

returns almost immediately and does not reduce the number of fragments
in /path/to/file. However, running

$ btrfs fi defrag /path/to/file

does reduce the number of fragments.


Transcript:
eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ sync

eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ filefrag
/home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1YygQLPowcpLwoNE.bCX4a---/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1rvNb.zifeXTwNQmAhQdkpU--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1oFfB25Ypui-NUlhLrvnCu---/ECRYPTFS_FNEK_ENCRYPTED.FXbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1e.GaDiBl08xl5bZAxYj09kaLyAQQuN1NY-zCYqLw21g-
/home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1YygQLPowcpLwoNE.bCX4a---/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1rvNb.zifeXTwNQmAhQdkpU--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1oFfB25Ypui-NUlhLrvnCu---/ECRYPTFS_FNEK_ENCRYPTED.FXbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1e.GaDiBl08xl5bZAxYj09kaLyAQQuN1NY-zCYqLw21g-:
1567 extents found

eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ time btrfs fi defrag
-r /home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--

real    0m0.006s
user    0m0.000s
sys    0m0.004s

eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ sync

eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ filefrag
/home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1YygQLPowcpLwoNE.bCX4a---/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1rvNb.zifeXTwNQmAhQdkpU--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1oFfB25Ypui-NUlhLrvnCu---/ECRYPTFS_FNEK_ENCRYPTED.FXbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1e.GaDiBl08xl5bZAxYj09kaLyAQQuN1NY-zCYqLw21g-
/home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1YygQLPowcpLwoNE.bCX4a---/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1rvNb.zifeXTwNQmAhQdkpU--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1oFfB25Ypui-NUlhLrvnCu---/ECRYPTFS_FNEK_ENCRYPTED.FXbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1e.GaDiBl08xl5bZAxYj09kaLyAQQuN1NY-zCYqLw21g-:
1567 extents found

eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ btrfs fi defrag
/home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1YygQLPowcpLwoNE.bCX4a---/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1rvNb.zifeXTwNQmAhQdkpU--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1oFfB25Ypui-NUlhLrvnCu---/ECRYPTFS_FNEK_ENCRYPTED.FXbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1e.GaDiBl08xl5bZAxYj09kaLyAQQuN1NY-zCYqLw21g-

eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ sync

eric@europa:~/filefrag/2015-07-11 09:53:32-06:00$ filefrag
/home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1YygQLPowcpLwoNE.bCX4a---/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1rvNb.zifeXTwNQmAhQdkpU--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1oFfB25Ypui-NUlhLrvnCu---/ECRYPTFS_FNEK_ENCRYPTED.FXbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1e.GaDiBl08xl5bZAxYj09kaLyAQQuN1NY-zCYqLw21g-
/home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1MzDigXwKSteYI4y1XLf7qE--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1YygQLPowcpLwoNE.bCX4a---/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1rvNb.zifeXTwNQmAhQdkpU--/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1oFfB25Ypui-NUlhLrvnCu---/ECRYPTFS_FNEK_ENCRYPTED.FXbZ4j3re5lQYkQsG5UhAnMElrqSQB7o7Dt1e.GaDiBl08xl5bZAxYj09kaLyAQQuN1NY-zCYqLw21g-:
15 extents found

>> btrfs --version: Btrfs v3.17
>
> I recommend to update both :), but for the defragging it should not matter.

As long as it doesn't affect defragging, I think I'll stick with what
I've got. There isn't any critical data on this machine that I would
miss.

> […]
>> Terminal Transcript
>> -------------------
>>
>> eric@europa:~/filefrag/2015-07-09$ filefrag
>> /home/.ecryptfs/eric/.Private/ECRYPTFS_FNEK_ENCRYPTED.FWbZ4j3re5lQYkQsG5Uh
> […]
>
> Nice, someone like me searching the correspondending file name in ecryptfs
> for defragmenting :)

I was kind of surprised that ecryptfs-find uses inode numbers and the
find command to locate the encrypted name of a file. It seems like
there should be a better, much faster way to do this.

Thanks,
Eric
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