使用fuser解除loop设备占用

SEO#

结束占用磁盘设备的进程
结束读取磁盘无法umount的进程

背景#

在Ubuntu上完全卸载snap后一直残留一个loop device无法移除

# lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop34        7:34   0 105.8M  1 loop 
# udisksctl loop-delete -b /dev/loop34
Error deleting loop device /dev/loop34: GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._g_2dbd_2dloop_2derror_2dquark.Code1: Error deleting /dev/loop34: Failed to detach the backing file from the /dev/loop34 device: No such device or address

使用losetup -l显示背后的文件已经删除，且设备为只读状态

# losetup -l
NAME        SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE                                      DIO LOG-SEC
/dev/loop34         0      0         1  1 /var/lib/snapd/snaps/core_16202.snap (deleted)   0     512

使用lsof查看占用却无法kill -9

# ps aux | grep loop34
root     18578  0.0  0.0      0     0 ?        SN    2023   0:31 [loop34]
root     24300  0.0  0.0  17904  1052 pts/0    S+   14:14   0:00 grep --color=auto loop34
# kill -9 18578

希望删除这个loop device并解除占用

解决#

尝试了一系列方法，最后使用fuser解决

# fuser -km /dev/loop34
/dev/loop34:         16924e

再运行lsblk已经看不到占用了

参考#

linux - Can't unmount a loop backed file but there's no open files? - Server Fault