Commit 930b7c32 authored by Yuriy Belikov's avatar Yuriy Belikov Committed by Amir Goldstein
Browse files

overlayfs.rst: update metacopy section in overlayfs documentation 



- Provide info about trusted.overlay.metacopy extended attribute
- Minor rephrasing regarding copy-up operation with metacopy=on

Signed-off-by: default avatarYuriy Belikov <yuriybelikov1@gmail.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
parent 7d6899fb

Documentation/filesystems/overlayfs.rst

+5 −2
Original line number Diff line number Diff line
@@ -367,8 +367,11 @@ Metadata only copy up 


When the "metacopy" feature is enabled, overlayfs will only copy

up metadata (as opposed to whole file), when a metadata specific operation

like chown/chmod is performed. Full file will be copied up later when

file is opened for WRITE operation.

like chown/chmod is performed. An upper file in this state is marked with

"trusted.overlayfs.metacopy" xattr which indicates that the upper file

contains no data.  The data will be copied up later when file is opened for

WRITE operation.  After the lower file's data is copied up,

the "trusted.overlayfs.metacopy" xattr is removed from the upper file.



In other words, this is delayed data copy up operation and data is copied

up when there is a need to actually modify data.