在终端下调整ext4文件系统的大小

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在带有GUI的Linux系统中，我们可以通过GParted方便地管理磁盘分区，但是在很多时候我们没有条件使用GUI工具，所以本文简单介绍一下如何在命令行界面调整ext4分区的大小。

系统环境

  • 待分配分区：/dev/sdb1
  • 分区工具：fdisk
  • 文件系统检查工具：e2fsck
  • 文件系统调整工具：resize2fs

扩大文件系统

首先需要明确，决定文件系统上限的是其所在的分区大小，因此，如果待调整的文件系统已经占满了整个分区，那么在调整文件系统之前，需要先调整分区大小，本文假设待调整分区的后面仍然有可用的空间。

重建分区

原始状态下，分区dev/sdb1有512M，我们要把它调整为768M。

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NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb      8:16   0     1G  0 disk
└─sdb1   8:17   0   512M  0 part /mnt

  1. 解挂分区

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    sudo umount /mnt

  2. 删除旧分区

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    sudo fdisk /dev/sdb
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    Welcome to fdisk (util-linux 2.31.1).
    Changes will remain in memory only, until you decide to write them.
    Be careful before using the write command.


    Command (m for help): p
    Disk /dev/sdb: 1 GiB, 1073741824 bytes, 2097152 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disklabel type: dos
    Disk identifier: 0x485cc8a2

    Device     Boot Start     End Sectors  Size Id Type
    /dev/sdb1        2048 1050623 1048576  512M 83 Linux

    Command (m for help): d
    Selected partition 1
    Partition 1 has been deleted.

    Command (m for help): w
    The partition table has been altered.
    Calling ioctl() to re-read partition table.
    Syncing disks.

  3. 创建新分区

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    sudo fdisk /dev/sdb
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    Welcome to fdisk (util-linux 2.31.1).
    Changes will remain in memory only, until you decide to write them.
    Be careful before using the write command.


    Command (m for help): n
    Partition type
       p   primary (0 primary, 0 extended, 4 free)
       e   extended (container for logical partitions)
    Select (default p): p
    Partition number (1-4, default 1):
    First sector (2048-2097151, default 2048):
    Last sector, +sectors or +size{K,M,G,T,P} (2048-2097151, default 2097151): +768M

    Created a new partition 1 of type 'Linux' and of size 768 MiB.
    Partition #1 contains a ext4 signature.

    Do you want to remove the signature? [Y]es/[N]o: n

    Command (m for help): w

    The partition table has been altered.
    Calling ioctl() to re-read partition table.
    Syncing disks.

    注意：新分区的起始扇区必须跟老分区的起始扇区一致。

检查文件系统

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sudo e2fsck -f /dev/sdb1
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e2fsck 1.44.1 (24-Mar-2018)
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
/dev/sdb1: 12/32768 files (0.0% non-contiguous), 6354/131072 blocks

调整文件系统

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sudo resize2fs /dev/sdb1
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resize2fs 1.44.1 (24-Mar-2018)
Resizing the filesystem on /dev/sdb1 to 196608 (4k) blocks.
The filesystem on /dev/sdb1 is now 196608 (4k) blocks long.

缩小文件系统

缩小文件系统理论上不需要调整分区，但是这样会造成空间的浪费，其操作顺序与扩大文件系统相反。我们现在把刚才的768M的文件系统再调整为512M。

检查文件系统

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sudo e2fsck -f /dev/sdb1
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e2fsck 1.44.1 (24-Mar-2018)
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
/dev/sdb1: 12/49152 files (0.0% non-contiguous), 7447/196608 blocks

调整文件系统

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sudo resize2fs /dev/sdb1 512M
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resize2fs 1.44.1 (24-Mar-2018)
Resizing the filesystem on /dev/sdb1 to 131072 (4k) blocks.
The filesystem on /dev/sdb1 is now 131072 (4k) blocks long.

重建分区

  1. 删除旧分区

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    sudo fdisk /dev/sdb
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    Command (m for help): p
    Disk /dev/sdb: 1 GiB, 1073741824 bytes, 2097152 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disklabel type: dos
    Disk identifier: 0x485cc8a2

    Device     Boot Start     End Sectors  Size Id Type
    /dev/sdb1        2048 1574911 1572864  768M 83 Linux

    Command (m for help): d
    Selected partition 1
    Partition 1 has been deleted.

    Command (m for help): w
    The partition table has been altered.
    Calling ioctl() to re-read partition table.
    Syncing disks.

  2. 创建新分区

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    sudo fdisk /dev/sdb
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    Command (m for help): p
    Disk /dev/sdb: 1 GiB, 1073741824 bytes, 2097152 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disklabel type: dos
    Disk identifier: 0x485cc8a2

    Command (m for help): n
    Partition type
       p   primary (0 primary, 0 extended, 4 free)
       e   extended (container for logical partitions)
    Select (default p): p
    Partition number (1-4, default 1):
    First sector (2048-2097151, default 2048):
    Last sector, +sectors or +size{K,M,G,T,P} (2048-2097151, default 2097151): +512M

    Created a new partition 1 of type 'Linux' and of size 512 MiB.
    Partition #1 contains a ext4 signature.

    Do you want to remove the signature? [Y]es/[N]o: n

    Command (m for help): w

    The partition table has been altered.
    Calling ioctl() to re-read partition table.
    Syncing disks.

总结

本文所描述的场景仅仅适用于分区后面仍然有可分配的空间，如果后面紧跟着其它分区或者该分区是最后一个分区，会涉及到分区的移动，以后有机会会讲到。

参考资料

Resize Partition and Filesystem with fdisk & resize2fs