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| -rw-r--r-- | Documentation/filesystems/overlayfs.rst | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst index a3e588dc8437..1ef4ef38b542 100644 --- a/Documentation/filesystems/overlayfs.rst +++ b/Documentation/filesystems/overlayfs.rst @@ -97,11 +97,13 @@ directory trees to be in the same filesystem and there is no requirement that the root of a filesystem be given for either upper or lower. -The lower filesystem can be any filesystem supported by Linux and does -not need to be writable. The lower filesystem can even be another -overlayfs. The upper filesystem will normally be writable and if it -is it must support the creation of trusted.* extended attributes, and -must provide valid d_type in readdir responses, so NFS is not suitable. +A wide range of filesystems supported by Linux can be the lower filesystem, +but not all filesystems that are mountable by Linux have the features +needed for OverlayFS to work. The lower filesystem does not need to be +writable. The lower filesystem can even be another overlayfs. The upper +filesystem will normally be writable and if it is it must support the +creation of trusted.* extended attributes, and must provide valid d_type in +readdir responses, so NFS is not suitable. A read-only overlay of two read-only filesystems may use any filesystem type. |