free space inode generation (0) did not match free space cache generation

Hello,

I have a file-system on which I cannot write anymore (no space left on device, which is not true

root@homeserver:~/btrfs/integration/devel# df -h
Dateisystem    Größe Benutzt Verf. Verw% Eingehängt auf
/dev/sdd2        30G     24G  5,1G   83% /mnt/test1
)

About the filesystem:

root@homeserver:~/btrfs/integration/devel# ./btrfs fi show /mnt/test1
Label: 'ROOT_BTRFS_RAID'  uuid: a2d5f2db-04ca-413a-aee1-cb754aa8fba5
        Total devices 2 FS bytes used 11.84GiB
        devid    1 size 14.85GiB used 14.67GiB path /dev/sde2
        devid    2 size 14.65GiB used 14.65GiB path /dev/sdd2
Btrfs this-will-become-v3.13-48-g57c3600

Check of the filesystem:

root@homeserver:~/btrfs/integration/devel# umount /mnt/test1
root@homeserver:~/btrfs/integration/devel# ./btrfsck /dev/sdd2
Checking filesystem on /dev/sdd2
UUID: a2d5f2db-04ca-413a-aee1-cb754aa8fba5
checking extents
checking free space cache
free space inode generation (0) did not match free space cache generation (41)
free space inode generation (0) did not match free space cache generation (7380)
free space inode generation (0) did not match free space cache generation (3081)
checking fs roots
checking csums
checking root refs
found 3680170466 bytes used err is 0
total csum bytes: 10071956
total tree bytes: 2398781440
total fs tree bytes: 2308784128
total extent tree bytes: 74203136
btree space waste bytes: 372004575
file data blocks allocated: 341759610880
 referenced 75292241920
Btrfs this-will-become-v3.13-48-g57c3600

Before the btrfsck I did a
mount -o clear_cache /dev/sdd2 /mnt/test1/

which in fact reduced the number of error messages (did not match free space cache generation) from more than ten to just three.

I do have a backup of the FS and in fact it would have been quicker just whiping the disk and using the backup (just 16GB), than writing this message. But:
Is it of interest to look at fixing this for someone, so that the development of btrfs can profit of this, or should I just whipe the disc?

Greetings,
Hendrik

Hendrik Friedel posted on Sat, 22 Mar 2014 19:13:48 +0100 as excerpted:

That's a FAQ and I just replied to a different thread with a detailed explanation and procedure for fixing. See

http://permalink.gmane.org/gmane.comp.file-systems.btrfs/33643

It's linked there, but you'll also want to read up on the btrfs wiki, particularly the free-space and balance sections of the FAQ, along with the balance filters page.

https://btrfs.wiki.kernel.org

Bookmark it! =:^)

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"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman