Test that if we write into an unwritten extent of a file when there
is no more space left to allocate in the filesystem and then
snapshot the file's subvolume, after a clean shutdown the data was
not lost.
This test is motivated by a bug found by Robbie Ko for which there
is a fix whose patch title is:
"Btrfs: fix unexpected failure of nocow buffered writes after
snapshotting when low on space"
Reported-by: Robbie Ko <robbieko@synology.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Filipe Manana