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authorAmir Goldstein <amir73il@gmail.com>2023-07-07 11:20:41 +0300
committerAmir Goldstein <amir73il@gmail.com>2023-08-12 19:02:50 +0300
commitd9544c1b0d9e14a66936814dcc8a85861ea1b99f (patch)
treeb8c8a2f1daee13141cd107888e932902873569d4 /Documentation/filesystems/overlayfs.rst
parentb0504bfe1b8acdcfb5ef466581d930835ef3c49e (diff)
downloadlinux-d9544c1b0d9e14a66936814dcc8a85861ea1b99f.tar.xz
ovl: store persistent uuid/fsid with uuid=on
With uuid=on, store a persistent uuid in xattr on the upper dir to give the overlayfs instance a persistent identifier. This also makes f_fsid persistent and more reliable for reporting fid info in fanotify events. uuid=on is not supported on non-upper overlayfs or with upper fs that does not support xattrs. Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Diffstat (limited to 'Documentation/filesystems/overlayfs.rst')
-rw-r--r--Documentation/filesystems/overlayfs.rst3
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
index d55381d3fa0f..8275ed735f77 100644
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -671,6 +671,9 @@ controlled by the "uuid" mount option, which supports these values:
UUID of underlying layers is ignored.
- "on":
UUID of overlayfs is generated and used to report a unique fsid.
+ 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.
Volatile mount