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为什么我无法在环回上挂载刚刚创建的图像？

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为什么我无法在环回上挂载刚刚创建的图像？

我通常在安装磁盘（文件系统）映像时遇到麻烦，因此我创建了一个通用磁盘映像，但发现它也无法安装！

dd if=/dev/zero of=image.dd bs=1k count=2048
mkfs -i 4096 -F -v -m0 image.dd

到目前为止一切顺利。我可以fsck在图像上运行，一切正常：

$ fsck.ext2 -f image.dd
e2fsck 1.42.13 (17-May-2015)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
image.dd: 11/512 files (0.0% non-contiguous), 90/2048 blocks

但是当我尝试安装它时，它失败了：

$ mkdir mnt;sudo mount -orw,loop image.dd mnt
mount: /dev/loop0: can't read superblock

奇怪的是，当我看时，dmesg我看到了 I/O 错误！

[19994.133342] blk_update_request: 4 callbacks suppressed
[19994.133357] blk_update_request: I/O error, dev loop0, sector 3968
[19994.134218] blk_update_request: I/O error, dev loop0, sector 3968
[19994.134221] Buffer I/O error on dev loop0, logical block 496, async page read
[19994.134278] blk_update_request: I/O error, dev loop0, sector 3968
[19994.134279] Buffer I/O error on dev loop0, logical block 496, async page read
[19994.134414] blk_update_request: I/O error, dev loop0, sector 2
[19994.134418] EXT4-fs (loop0): unable to read superblock
[19994.134433] blk_update_request: I/O error, dev loop0, sector 2
[19994.134435] EXT4-fs (loop0): unable to read superblock
[19994.134446] blk_update_request: I/O error, dev loop0, sector 2
[19994.134447] EXT4-fs (loop0): unable to read superblock
[19994.134458] blk_update_request: I/O error, dev loop0, sector 0
[19994.134460] SQUASHFS error: squashfs_read_data failed to read block 0x0
[19994.134461] squashfs: SQUASHFS error: unable to read squashfs_super_block

我也尝试使用该losetup命令，结果相同：

sudo losetup /dev/loop0 image.dd
sudo mount -orw /dev/loop0 mnt

答案1

您的系统已崩溃。前两个命令成功，因为所有操作都发生在页面缓存中。当您实际尝试挂载它时，页面缓存被绕过，这时事情就会出错，因为文件所在的设备出了问题。

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