Hi folks, On 2023/8/23 01:29, Amir Goldstein wrote:
On Tue, Aug 22, 2023 at 7:19 PM Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
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I proposed to look at the two features independently: 1. Nesting of overlayfs xattrs (patch 3/5) 2. Alternative format for whiteout (overlay.whiteout) that can be used by container tools converting OCI/tar images to overlayfs images Together, they provide a solution to Alexander's use case. IIUC, the way this is intended to work is that mkfs.composefs is running inside a container, whose work directory is overlayfs and it composes some lower layers on that host mounted overlayfs. mkfs.composefs composes layers with overlay.{metacopy,whiteout,redirect} xattrs (up to here it is standard mkfs.composefs) and because those layers are stored in overlayfs, the xattrs are stored in the host fs as overlay.overlay.*. I hope I got the use case correctly?
Sorry for the dumb questions below. I'm interested in the use cases: after checking the previous github issue and emails (sorry if I'm still missing something), I'm curious about this too. I totally understand how it plans to work and how it works (by using escape xattr prefixes) but I'm not sure if I'm quite understand the original issue: Do composefs use cases store overlayfs xattrs in the meta-only layer? if so, such layer is actually hand-crafted by mkfs. Why do we need a way to keep escape xattrs on the underlay overlayfs? Does the other layer are data-only layers (do we keep some overlay xattrs in these data-only layers)? Thanks, Gao Xiang
