Commit 4330e183 authored Mar 09, 2017 by Qu Wenruo Committed by David Sterba Aug 16, 2017

btrfs: Do chunk level check for degraded rw mount



Now use the btrfs_check_rw_degradable() to check if we can mount in the
degraded mode.

With this patch, we can mount in the following case:
 # mkfs.btrfs -f -m raid1 -d single /dev/sdb /dev/sdc
 # wipefs -a /dev/sdc
 # mount /dev/sdb /mnt/btrfs -o degraded
 As the single data chunk is only on sdb, so it's OK to mount as
 degraded, as missing one device is OK for RAID1.

But still fail in the following case as expected:
 # mkfs.btrfs -f -m raid1 -d single /dev/sdb /dev/sdc
 # wipefs -a /dev/sdb
 # mount /dev/sdc /mnt/btrfs -o degraded
 As the data chunk is only in sdb, so it's not OK to mount it as
 degraded.

Reported-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Reported-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 21634a19

fs/btrfs/disk-io.c

+3 −8

Original line number	Diff line number	Diff line
		@@ -3035,15 +3035,10 @@ retry_root_backup:
		btrfs_err(fs_info, "failed to read block groups: %d", ret);
		goto fail_sysfs;
		}
		fs_info->num_tolerated_disk_barrier_failures =
		btrfs_calc_num_tolerated_disk_barrier_failures(fs_info);
		if (fs_info->fs_devices->missing_devices >
		fs_info->num_tolerated_disk_barrier_failures &&
		!(sb->s_flags & MS_RDONLY)) {

		if (!(sb->s_flags & MS_RDONLY) && !btrfs_check_rw_degradable(fs_info)) {
		btrfs_warn(fs_info,
		"missing devices (%llu) exceeds the limit (%d), writeable mount is not allowed",
		fs_info->fs_devices->missing_devices,
		fs_info->num_tolerated_disk_barrier_failures);
		"writeable mount is not allowed due to too many missing devices");
		goto fail_sysfs;
		}

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