为什么环回设备创建会出现故障？

发布于 2024-09-18 09:16:38 字数 1320 浏览 5 评论 0原文

在代码的底部，您可以看到它失败了。事实上，我也会在一开始就把它放在这里，因为这是我需要解决的问题：

[350591.924819] EXT4-fs (loop0): bad geometry: block count 9750806 exceeds size of device (9750168 blocks)

我不明白为什么该设备据说太小。我两天前用普通的 fdisk 创建了这个分区，它是用 ext4 创建和格式化的，除了要格式化的分区 (/dev/sdb2) 之外不提供任何选项。

我能想到的唯一解释是 ext4 的分区大小不知何故错误，但这似乎不太可能。我的数学出了什么问题？偏移量是正确的，您可以使用 file 命令看到，并且大小也应该正确，因为 End - Start 的扇区数相同减 1，就像它应该的那样（磁盘从扇区 1 开始并以扇区结束2 将是 2 - 1 = 1 并且有两个扇区）。

# sfdisk -luS /dev/sdb

Disk /dev/sdb: 9729 cylinders, 255 heads, 63 sectors/track
Units = sectors of 512 bytes, counting from 0

   Device Boot    Start       End   #sectors  Id  System
/dev/sdb2      78295040 156296384   78001345  83  Linux

# losetup -r -f --show -o $((78295040 * 512)) --sizelimit $((78001345 * 512)) /dev/sdb
/dev/loop0
# file -s /dev/loop0
/dev/loop0: Linux rev 1.0 ext4 filesystem data (needs journal recovery) (extents) (large files) (huge files)
# mount -o ro -t ext4 /dev/loop0 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so
# dmesg | tail -n 1
[350591.924819] EXT4-fs (loop0): bad geometry: block count 9750806 exceeds size of device (9750168 blocks)

原文

At the bottom of the code you can see it failing. In fact, I'll put it here at the start too because it is the problem I need to solve:

[350591.924819] EXT4-fs (loop0): bad geometry: block count 9750806 exceeds size of device (9750168 blocks)

I don't understand why the device is supposedly too small. I made this partition two days ago with normal fdisk, it was created and formatted with ext4 supplying no options other than the partition (/dev/sdb2) to format.

The only explaination I can think of is that ext4 has the size of the partition wrong somehow but that seems very unlikely. What is wrong with my math? The offset is correct, you can see that with the file command, and the size should be correct too because End - Start comes to the same number of sectors minus 1, just like it should (A disk starting on sector 1 and ending on sector 2 would be 2 - 1 = 1 and have two sectors).

# sfdisk -luS /dev/sdb

Disk /dev/sdb: 9729 cylinders, 255 heads, 63 sectors/track
Units = sectors of 512 bytes, counting from 0

   Device Boot    Start       End   #sectors  Id  System
/dev/sdb2      78295040 156296384   78001345  83  Linux

# losetup -r -f --show -o $((78295040 * 512)) --sizelimit $((78001345 * 512)) /dev/sdb
/dev/loop0
# file -s /dev/loop0
/dev/loop0: Linux rev 1.0 ext4 filesystem data (needs journal recovery) (extents) (large files) (huge files)
# mount -o ro -t ext4 /dev/loop0 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so
# dmesg | tail -n 1
[350591.924819] EXT4-fs (loop0): bad geometry: block count 9750806 exceeds size of device (9750168 blocks)

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