Deleting file on btrfs partition gives "No space left on device"

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Environment

SUSE Linux Enterprise Server 11 Service Pack 2

Situation

On a SLES machine a file cannot be removed from the btrfs partition, new files cannot be created as well.
All snapshots were removed and the partition is showing enough of free space:

testsystem:~ # btrfs fi df /mnt/log/
Data: total=435.01GiB, used=347.67GiB
System, DUP: total=8.00MiB, used=56.00KiB
System: total=4.00MiB, used=0.00
Metadata, DUP: total=14.50GiB, used=3.44GiB
Metadata: total=8.00MiB, used=0.00

Resolution

A workaround is available:

umount /mnt/log
mount '-o clear_cache' /dev/mapper/mpatha_part1 /mnt/log

Cause

There is a discrepancy between cached free space and the actual status. This is rebuilt after remounting partition with clear_cache option.

Disclaimer

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