Commit 65f26738 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi

ovl: update documentation w.r.t. constant inode numbers

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 5b6c9053
...@@ -21,12 +21,19 @@ from accessing the corresponding object from the original filesystem. ...@@ -21,12 +21,19 @@ from accessing the corresponding object from the original filesystem.
This is most obvious from the 'st_dev' field returned by stat(2). This is most obvious from the 'st_dev' field returned by stat(2).
While directories will report an st_dev from the overlay-filesystem, While directories will report an st_dev from the overlay-filesystem,
all non-directory objects will report an st_dev from the lower or non-directory objects may report an st_dev from the lower filesystem or
upper filesystem that is providing the object. Similarly st_ino will upper filesystem that is providing the object. Similarly st_ino will
only be unique when combined with st_dev, and both of these can change only be unique when combined with st_dev, and both of these can change
over the lifetime of a non-directory object. Many applications and over the lifetime of a non-directory object. Many applications and
tools ignore these values and will not be affected. tools ignore these values and will not be affected.
In the special case of all overlay layers on the same underlying
filesystem, all objects will report an st_dev from the overlay
filesystem and st_ino from the underlying filesystem. This will
make the overlay mount more compliant with filesystem scanners and
overlay objects will be distinguishable from the corresponding
objects in the original filesystem.
Upper and Lower Upper and Lower
--------------- ---------------
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