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Kernel: Enable metacopy and redirect_dir in overlayfs #170

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dongsupark opened this issue Aug 24, 2020 · 2 comments · Fixed by flatcar/coreos-overlay#691
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Kernel: Enable metacopy and redirect_dir in overlayfs #170

dongsupark opened this issue Aug 24, 2020 · 2 comments · Fixed by flatcar/coreos-overlay#691
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kind/feature A feature request

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@dongsupark
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Current situation
At the moment, Kernel module overlay enables its features, neither metacopy nor redirect_dir, as it is given so by default. According to the overlayfs developer Amir Goldstein at LPC 2020, distros and container runtimes should enable both features for overlayfs.

We should do so, and go through the ordinary CI to see if there is any regression.

Kernel configs:

  • metacopy: CONFIG_OVERLAY_FS_METACOPY
  • redirect_dir: CONFIG_OVERLAY_FS_REDIRECT_DIR

See also https://github.com/amir73il/overlayfs/wiki .

@dongsupark dongsupark added the kind/feature A feature request label Aug 24, 2020
@goochjj
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goochjj commented Sep 24, 2020

+1

@dongsupark dongsupark self-assigned this Nov 17, 2020
dongsupark added a commit to dongsupark/coreos-overlay that referenced this issue Nov 17, 2020
Enable CONFIG_OVERLAY_FS_METACOPY, metadata only copy up feature
in overlayfs. When turned on, overlayfs will only copy up metadata
when a metadata specific operation like chown/chmod is performed.
Full file will be copied up later when file is opened for WRITE
operation. More or less like delayed data copy up operation.

Enable CONFIG_OVERLAY_FS_REDIRECT_DIR, which is equivalent to
"redirect_dir=on" in the kernel command-line. When turned on, overlayfs
will copy up directory first, before the actual contents.

flatcar/Flatcar#170
dongsupark added a commit to flatcar/coreos-overlay that referenced this issue Nov 17, 2020
Enable CONFIG_OVERLAY_FS_METACOPY, metadata only copy up feature
in overlayfs. When turned on, overlayfs will only copy up metadata
when a metadata specific operation like chown/chmod is performed.
Full file will be copied up later when file is opened for WRITE
operation. More or less like delayed data copy up operation.

Enable CONFIG_OVERLAY_FS_REDIRECT_DIR, which is equivalent to
"redirect_dir=on" in the kernel command-line. When turned on, overlayfs
will copy up directory first, before the actual contents.

flatcar/Flatcar#170
dongsupark added a commit to flatcar/coreos-overlay that referenced this issue Nov 17, 2020
Enable CONFIG_OVERLAY_FS_METACOPY, metadata only copy up feature
in overlayfs. When turned on, overlayfs will only copy up metadata
when a metadata specific operation like chown/chmod is performed.
Full file will be copied up later when file is opened for WRITE
operation. More or less like delayed data copy up operation.

Enable CONFIG_OVERLAY_FS_REDIRECT_DIR, which is equivalent to
"redirect_dir=on" in the kernel command-line. When turned on, overlayfs
will copy up directory first, before the actual contents.

See also flatcar/Flatcar#170
@dongsupark
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Filed PR flatcar/coreos-overlay#691

t-lo pushed a commit to flatcar/coreos-overlay that referenced this issue Nov 18, 2020
Enable CONFIG_OVERLAY_FS_METACOPY, metadata only copy up feature
in overlayfs. When turned on, overlayfs will only copy up metadata
when a metadata specific operation like chown/chmod is performed.
Full file will be copied up later when file is opened for WRITE
operation. More or less like delayed data copy up operation.

Enable CONFIG_OVERLAY_FS_REDIRECT_DIR, which is equivalent to
"redirect_dir=on" in the kernel command-line. When turned on, overlayfs
will copy up directory first, before the actual contents.

See also flatcar/Flatcar#170
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