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| author | Amir Goldstein <amir73il@gmail.com> | 2023-07-07 11:26:29 +0300 |
|---|---|---|
| committer | Amir Goldstein <amir73il@gmail.com> | 2023-08-12 19:02:50 +0300 |
| commit | cbb44f0935974bba997f8db0458fac5739ae0009 (patch) | |
| tree | c32f08f3a699457bbcf17a0e6b6e180d50732233 /Documentation/filesystems | |
| parent | d9544c1b0d9e14a66936814dcc8a85861ea1b99f (diff) | |
| download | linux-cbb44f0935974bba997f8db0458fac5739ae0009.tar.gz | |
ovl: auto generate uuid for new overlay filesystems
Add a new mount option uuid=auto, which is the default.
If a persistent UUID xattr is found it is used.
Otherwise, an existing ovelrayfs with copied up subdirs in upper dir
that was never mounted with uuid=on retains the null UUID.
A new overlayfs with no copied up subdirs, generates the persistent UUID
on first mount.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/overlayfs.rst | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst index 8275ed735f7747..35853906accb38 100644 --- a/Documentation/filesystems/overlayfs.rst +++ b/Documentation/filesystems/overlayfs.rst @@ -664,7 +664,7 @@ UUID and fsid The UUID of overlayfs instance itself and the fsid reported by statfs(2) are controlled by the "uuid" mount option, which supports these values: -- "null": (default) +- "null": UUID of overlayfs is null. fsid is taken from upper most filesystem. - "off": UUID of overlayfs is null. fsid is taken from upper most filesystem. @@ -674,6 +674,12 @@ controlled by the "uuid" mount option, which supports these values: UUID is stored in xattr "trusted.overlay.uuid", making overlayfs fsid unique and persistent. This option requires an overlayfs with upper filesystem that supports xattrs. +- "auto": (default) + UUID is taken from xattr "trusted.overlay.uuid" if it exists. + Upgrade to "uuid=on" on first time mount of new overlay filesystem that + meets the prerequites. + Downgrade to "uuid=null" for existing overlay filesystems that were never + mounted with "uuid=on". Volatile mount |