BTRFS error after clearing cache

BTRFS error after clearing cache

[yzb3]

Hello,

I wanted to make sure that my boot slowdown was related to space_cache so I rebooted the PC several times and it did become slower again. What is more, it doesn't seem like I even need to generate any actual IO traffic to trigger this.

I thought I might give clear_cache a shot again and to test the boot speed with nospace_cache as well. After first booting with clear_cache,nospace_cache and nospace_cache afterwards I was unhappy about the boot speed, so I decided to clear the nospace_cache argument so that the cache would be rebuilt. However, even though my boot speed did improve (not well enough, though), I received 2 errors (this is also the output of dmesg | grep BTRFS):

[    5.528707] BTRFS error (device sda2): block group 1103101952 has wrong amount of free space
[    5.529630] BTRFS error (device sda2): failed to load free space cache for block group 1103101952

It comes up after every reboot now. The output of dmesg | grep trfs (no 'b', because it is inconsistent) is:

[    1.225343] Btrfs loaded
[    1.245586] btrfs: disk space caching is enabled
[    1.245588] btrfs: has skinny extents

Any ideas on how I can remove this error? This doesn't break my boot or anything, but it probably slows things down, leaves some fs garbage etc. By the way, it would be a good idea to be able to search for a consistent value in dmesg.

Re: BTRFS error after clearing cache

[Duncan]

yzb3 posted on Sun, 10 Nov 2013 17:15:14 +0100 as excerpted:

> The output of dmesg | grep trfs (no 'b', because it is inconsistent)

You know about grep's -i, --ignore-case option, right?  (The GNU grep 
manpage says -i is POSIX specified, so should be grep-origin agnostic.)

But your case for log consistency remains a valid point none-the-less.  
-i shouldn't be necessary.  Consistency is good! =:^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

RE: BTRFS error after clearing cache

[yzb3]

>Hello,

>I wanted to make sure that my boot slowdown was related to space_cache so I rebooted the PC several times and
>it did become slower again. What is more, it doesn't seem like I even need to generate any actual IO traffic
>to trigger this.

>I thought I might give clear_cache a shot again and to test the boot speed with nospace_cache as well. After
>first booting with clear_cache,nospace_cache and nospace_cache afterwards I was unhappy about the
>boot speed, so I decided to clear the nospace_cache argument so that the cache would be rebuilt. However,
>even though my boot speed did improve (not well enough, though), I received 2 errors (this is also the
>output of dmesg | grep BTRFS):

>[    5.528707] BTRFS error (device sda2): block group 1103101952 has wrong amount of free space
>[    5.529630] BTRFS error (device sda2): failed to load free space cache for block group 1103101952

>It comes up after every reboot now. The output of dmesg | grep trfs (no 'b', because it is inconsistent) is:

>[    1.225343] Btrfs loaded
>[    1.245586] btrfs: disk space caching is enabled
>[    1.245588] btrfs: has skinny extents

>Any ideas on how I can remove this error? This doesn't break my boot or anything, but it probably slows things
>down, leaves some fs garbage etc. By the way, it would be a good idea to be able to search for a consistent
>value in dmesg.

This is still present under kernel 12.0; during a boot with clear_cache the messages are gone, but right after removing
this option (so that the cache is rebuilt) they appear again.