From d5791044d2e5749ef4de84161cec5532e2111540 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Fri, 11 May 2018 11:49:27 -0400 Subject: ovl: Provide a mount option metacopy=on/off for metadata copyup By default metadata only copy up is disabled. Provide a mount option so that users can choose one way or other. Also provide a kernel config and module option to enable/disable metacopy feature. metacopy feature requires redirect_dir=on when upper is present. Otherwise, it requires redirect_dir=follow atleast. As of now, metacopy does not work with nfs_export=on. So if both metacopy=on and nfs_export=on then nfs_export is disabled. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/Kconfig | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'fs/overlayfs/Kconfig') diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig index 9384164253ac..2ef91be2a04e 100644 --- a/fs/overlayfs/Kconfig +++ b/fs/overlayfs/Kconfig @@ -64,6 +64,7 @@ config OVERLAY_FS_NFS_EXPORT bool "Overlayfs: turn on NFS export feature by default" depends on OVERLAY_FS depends on OVERLAY_FS_INDEX + depends on !OVERLAY_FS_METACOPY help If this config option is enabled then overlay filesystems will use the index directory to decode overlay NFS file handles by default. @@ -103,3 +104,21 @@ config OVERLAY_FS_XINO_AUTO For more information, see Documentation/filesystems/overlayfs.txt If unsure, say N. + +config OVERLAY_FS_METACOPY + bool "Overlayfs: turn on metadata only copy up feature by default" + depends on OVERLAY_FS + select OVERLAY_FS_REDIRECT_DIR + help + If this config option is enabled then overlay filesystems will + copy up only metadata where appropriate and data copy up will + happen when a file is opened for WRITE operation. It is still + possible to turn off this feature globally with the "metacopy=off" + module option or on a filesystem instance basis with the + "metacopy=off" mount option. + + Note, that this feature is not backward compatible. That is, + mounting an overlay which has metacopy only inodes on a kernel + that doesn't support this feature will have unexpected results. + + If unsure, say N. -- cgit v1.2.3