From: Adam Borowski Date: Tue, 28 Mar 2017 16:55:05 +0200 Subject: btrfs: warn about RAID5/6 being experimental at mount time Bug-Debian: https://bugs.debian.org/863290 Origin: https://bugs.debian.org/863290#5 Too many people come complaining about losing their data -- and indeed, there's no warning outside a wiki and the mailing list tribal knowledge. Message severity chosen for consistency with XFS -- "alert" makes dmesg produce nice red background which should get the point across. Signed-off-by: Adam Borowski [bwh: Also add_taint() so this is flagged in bug reports] [2023-01-10: still accurate according to btrfs-progs own manpage: https://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git/commit/?id=922797e15590b836e377d6dc47b828356cafc2a9] [2024-03-17: still accurate; manpage is now in Documentation/btrfs-man5.rst implementation went from disk-io.c to super.c] --- fs/btrfs/super.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 101f786963d4..2c409bce1bf5 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -731,6 +731,18 @@ static void set_device_specific_options(struct btrfs_fs_info *fs_info) !fs_info->fs_devices->rotating) btrfs_set_opt(fs_info->mount_opt, SSD); + /* + * Warn about RAID5/6 being experimental at mount time + */ + if ((fs_info->avail_data_alloc_bits | + fs_info->avail_metadata_alloc_bits | + fs_info->avail_system_alloc_bits) & + BTRFS_BLOCK_GROUP_RAID56_MASK) { + btrfs_alert(fs_info, + "btrfs RAID5/6 is EXPERIMENTAL and has known data-loss bugs"); + add_taint(TAINT_AUX, LOCKDEP_STILL_OK); + } + /* * For devices supporting discard turn on discard=async automatically, * unless it's already set or disabled. This could be turned off by