cephfs目录下的每一个目录在元数据存储池中都有一个对应的对象，目录的扩展属性以及存放在它下面的子目录和文件的元数据信息都是存放在这个对象的omap属性中的，通过导出这个omap文件可以将目录的扩展属性解析出来。
首先导出目录testdir1的元数据，这个目录在cephfs的根目录下面，所以导出的时候要在根目录对应的对象1.00000000上去找。
[root@node101 10000000000.00000000]# rados -p metadata getomapval 1.00000000 testdir1_head testdir1_head
Writing to testdir1_head
[root@node101 10000000000.00000000]# hexdump -C testdir1_head
00000000 02 00 00 00 00 00 00 00 49 10 06 bf 01 00 00 00 |........I.......|
00000010 00 00 00 00 01 00 00 00 00 00 00 ad 9a a9 61 70 |..............ap|
00000020 42 61 00 ed 41 00 00 00 00 00 00 00 00 00 00 01 |Ba..A...........|
00000030 00 00 00 00 02 00 00 00 00 00 00 00 02 02 18 00 |................|
00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff |................|
00000050 ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 |................|
00000060 00 00 01 00 00 00 ff ff ff ff ff ff ff ff 00 00 |................|
00000070 00 00 00 00 00 00 00 00 00 00 ad 9a a9 61 70 42 |.............apB|
00000080 61 00 f6 7e a8 61 c8 90 1e 29 00 00 00 00 00 00 |a..~.a...)......|
00000090 00 00 03 02 28 00 00 00 00 00 00 00 00 00 00 00 |....(...........|
000000a0 ad 9a a9 61 70 42 61 00 04 00 00 00 00 00 00 00 |...apBa.........|
000000b0 00 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 |................|
000000c0 03 02 38 00 00 00 00 00 00 00 00 00 00 00 18 00 |..8.............|
000000d0 00 00 00 00 00 00 04 00 00 00 00 00 00 00 01 00 |................|
000000e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000000f0 00 00 00 00 00 00 ad 9a a9 61 70 42 61 00 03 02 |.........apBa...|
00000100 38 00 00 00 00 00 00 00 00 00 00 00 18 00 00 00 |8...............|
00000110 00 00 00 00 04 00 00 00 00 00 00 00 01 00 00 00 |................|
00000120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000130 00 00 00 00 ad 9a a9 61 70 42 61 00 10 00 00 00 |.......apBa.....|
00000140 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 |................|
00000150 00 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00 |................|
00000160 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff |................|
00000170 00 00 00 00 01 01 10 00 00 00 00 00 00 00 00 00 |................|
00000180 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000190 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f6 7e |...............~|
000001a0 a8 61 c8 90 1e 29 04 00 00 00 00 00 00 00 ff ff |.a...)..........|
000001b0 ff ff 01 01 16 00 00 00 00 00 00 00 00 00 00 00 |................|
000001c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fe ff |................|
000001e0 ff ff ff ff ff ff 00 00 00 00 |..........|
000001ea
截取目录大小元数据片段（大小为62字节）。
[root@node101 10000000000.00000000]# dd if=testdir1_head of=testdir1_head_1 bs=1 skip=192 count=62
62+0 records in
62+0 records out
62 bytes (62 B) copied, 0.000924797 s, 67.0 kB/s
[root@node101 10000000000.00000000]# hexdump -C testdir1_head_1
00000000 03 02 38 00 00 00 00 00 00 00 00 00 00 00 18 00 |..8.............|
00000010 00 00 00 00 00 00 04 00 00 00 00 00 00 00 01 00 |................|
00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000030 00 00 00 00 00 00 ad 9a a9 61 70 42 61 00 |.........apBa.|
0000003e
使用ceph-dencoder工具查看nest_info_t类别的解析结果。
rbytes表示目录大小，rfiles表示目录下的文件数量，rsubdirs表示目录下的子目录数量，rsnaprealms表示目录快照数量，rctime表示目录最后更新时间。
[root@node101 10000000000.00000000]# ceph-dencoder type 'nest_info_t' import testdir1_head_1 decode dump_json
{
"version": 0,
"rbytes": 24,
"rfiles": 4,
"rsubdirs": 1,
"rsnaprealms": 0,
"rctime": "2021-12-03 12:18:53.006374"
}
这个对应的是，其中ceph.dir.rctime使用的时间戳是以秒为单位计算的：
[root@node101 testdir1]# getfattr -dm . /vcluster/cephfs/testdir1/
getfattr: Removing leading '/' from absolute path names
# file: vcluster/cephfs/testdir1/
ceph.dir.entries="4"
ceph.dir.files="4"
ceph.dir.rbytes="1048600"
ceph.dir.rctime="1638505133.09133377000"
ceph.dir.rentries="5"
ceph.dir.rfiles="4"
ceph.dir.rsubdirs="1"
ceph.dir.subdirs="0"
查看目录中的文件数量和大小，与属性描述一致。
[root@node101 10000000000.00000000]# cd -
/vcluster/cephfs/testdir1
[root@node101 testdir1]# ll
total 1026
-rw-r--r-- 1 root root 1048576 Dec 3 12:18 1mfile
-rw-r--r-- 1 root root 8 Dec 2 16:18 file1
-rw-r--r-- 1 root root 8 Dec 2 16:28 file2
-rw-r--r-- 1 root root 8 Dec 2 18:03 file3