On Tue, Jun 20, 2023 at 10:35:32AM +0800, karel wrote:
> Not sure if I understand. According to docs BlueStore uses XFS
> partition to store metadata and another device to store raw data. It
> sounds like the XFS should be visible as a normal filesystem.
> From your description it sounds like the both is on the same device
> and we should not detect it as XFS log. If yes, then I do not
> understand why anyone use XFS log header for this purpose.
> XFS log detection seems robust, so I guess if libblkid detects the
> superblock then it's really the FS.
You can specify another disk device to store the external log for the XFS file system, similar to the following command:
mkfs.xfs -l logdev=/dev/nvme0n1p2,size=10000b /dev/nvme0n1p3
Using the dd command, you can copy the first sector of /dev/nvme0n1p2 to any sector between 17 and 512 of the
Ceph BlueStore file system for disk device A, for example, sector 51. After performing this action, a problem occurs where an additional file system,
efs_external_log, is created on the disk device A originally used for Ceph BlueStore.
This leads to udev errors and the loss of the disk device A's partlabel. for example
blkid -o udev -p /dev/xxxx
ID_FS_AMBIVALIENT=other:ceph_blueStore other:efs_external_log
Ceph BlueStore file system for Disk device A is exposed as a block device for users to use as a cloud disk.
Users can create an XFS External Log on it.
zhujun2
>> Signed-off-by: zhujun2 <zhujun2@xxxxxxxxxxxxxxxxxxxx>
>> ---
>> libblkid/src/superblocks/xfs.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/libblkid/src/superblocks/xfs.c b/libblkid/src/superblocks/xfs.c
>> index d8c6fb6d4..3686bd52b 100644
>> --- a/libblkid/src/superblocks/xfs.c
>> +++ b/libblkid/src/superblocks/xfs.c
>> @@ -259,6 +259,11 @@ static int probe_xfs_log(blkid_probe pr,
>> if (memcmp(&buf[i*512], "XFSB", 4) == 0)
>> return 1;
>>
>> + if (memcmp(&buf[i*512], "bluestore block device", 22) == 0) {
>> + DBG(LOWPROBE, ul_debug("\t device has ceph_bluestore ambivalent"));
>> + return 1;
>> + }
>> +
>> rhead = (struct xlog_rec_header *)&buf[i*512];
>>
>> if (xlog_valid_rec_header(rhead)) {
>> --
>> 2.20.1
