On Thu, Apr 05, 2018 at 11:16:36PM +0300, Amir Goldstein wrote: > On Mon, Apr 2, 2018 at 4:56 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > On Fri, Mar 30, 2018 at 07:52:17AM +0300, Amir Goldstein wrote: > >> On Thu, Mar 29, 2018 at 10:38 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > >> > 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. > >> > > >> > Like index feature, we verify on mount that upper root is not being > >> > reused with a different lower root. > >> > >> I don't see that in the patch > > > > Oh.., this is leftover from previous patches. Will remove this comment. > > I have completely got rid of dealing with ORIGIN when moving to > > REDIRECT based lookup. > > > >> > >> > This hopes to get the configuration > >> > right and detect the copied layers use case. But this does only so > >> > much as we don't verify all the lowers. So it is possible that a lower is > >> > missing and later data copy up fails. > >> > > >> > Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx> > >> > Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx> > >> > --- > >> > Documentation/filesystems/overlayfs.txt | 30 ++++++++++++++++++++++++- > >> > fs/overlayfs/Kconfig | 19 ++++++++++++++++ > >> > fs/overlayfs/ovl_entry.h | 1 + > >> > fs/overlayfs/super.c | 40 ++++++++++++++++++++++++++++++++- > >> > 4 files changed, 88 insertions(+), 2 deletions(-) > >> > > >> > diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt > >> > index 6ea1e64d1464..b7720e61973c 100644 > >> > --- a/Documentation/filesystems/overlayfs.txt > >> > +++ b/Documentation/filesystems/overlayfs.txt > >> > @@ -249,6 +249,30 @@ rightmost one and going left. In the above example lower1 will be the > >> > top, lower2 the middle and lower3 the bottom layer. > >> > > >> > > >> > +Metadata only copyup > >> > +-------------------- > >> > + > >> > +When metadata only copy up 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. > >> > + > >> > +IOW, this is delayed data copy up operation and data is copied up when > >> > +there is a need to actually modify data. > >> > + > > Vivek, > > Some nick picking here. > This is document is about the only decent documentation for overlayfs. > I always try to live up to the standards set by Neil who started it. > Abbreviations (IOW) doesn't seem right to me in this context. > Also, you'll notice that the form "copyup" does not appear in this document. > It may sound petty, but if people wish to read a coherent document about > overlayfs, we would be wise to maintain coherency in the phrases we use > throughout the document. Ok, I will remove IOW. Also will replace "copyup" with "copy up". Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
