[stable-11] filesystem: xfs resize: minimal required increment (#11033) #11042
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…ns#11033) Internally XFS uses allocation groups. Allocation groups have a maximum size of 1 TiB - 1 block. For devices >= 4 TiB XFS uses max size allocation groups. If a filesystem is extended and the last allocation group is already at max size, a new allocation group is added. An allocation group seems to require at least 64 4 KiB blocks. For devices with integer TiB size (>4), this creates a filesystem that has initially has 1 unused block per TiB size. The `resize` option detects this unused space, and tries to resize the filesystem. The xfs_growfs call is successful (exit 0), but does not increase the file system size. This is detected as repeated change in the task. Test case: ``` - hosts: localhost tasks: - ansible.builtin.command: cmd: truncate -s 4T /media/xfs.img creates: /media/xfs.img notify: loopdev xfs - ansible.builtin.meta: flush_handlers - name: pickup xfs.img resize ansible.builtin.command: cmd: losetup -c /dev/loop0 changed_when: false - community.general.filesystem: dev: "/dev/loop0" fstype: "xfs" - ansible.posix.mount: src: "/dev/loop0" fstype: "xfs" path: "/media/xfs" state: "mounted" # always shows a diff even for newly created filesystems - community.general.filesystem: dev: "/dev/loop0" fstype: "xfs" resizefs: true handlers: - name: loopdev xfs ansible.builtin.command: cmd: losetup /dev/loop0 /media/xfs.img ``` NB: If the last allocation group is not yet at max size, the filesystem can be resized. Detecting this requires considering the XFS topology. Other filesystems (at least ext4) also seem to require a minimum increment after the initial device size, but seem to use the entire device after initial creation. Fun observation: creating a 64(+) TiB filesystem leaves a 64(+) block gap at the end, that is allocated in a subsequent xfs_growfs call. Co-authored-by: Johannes Naab <[email protected]> (cherry picked from commit f594320)
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SUMMARY
Backport of #11033 to stable-11.
CC @jnaab
ISSUE TYPE
COMPONENT NAME
filesystem