Hi, I found out a bug in btrfs where a RWF_NOWRITE does not fail if we write to a range that starts with an extent followed by holes (since it requires allocating extent(s)). When writing a test case for fstests I noticed xfs fails with -EAGAIN as expected, but ext4 succeeds just like btrfs currently does: mkfs.ext4 -F /dev/sdb mount /dev/sdb /mnt xfs_io -f -d -c "pwrite -S 0xab -b 256K 0 256K" /mnt/bar xfs_io -c "fpunch 64K 64K" /mnt/bar sync xfs_io -d -c "pwrite -N -V 1 -b 128K -S 0xfe 0 128K" /mnt/bar Is this a known bug? Or is there a technical reason that makes it too expensive to check no extents will need to be allocated? Thanks. -- Filipe David Manana, “Whether you think you can, or you think you can't — you're right.”
