"upperdir" are combined into a merged directory:
mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,\
-workdir=/work /merged
+ workdir=/work /merged
The "workdir" needs to be an empty directory on the same filesystem
as upperdir.
seek offsets are assigned sequentially when the directories are read.
Thus if
+
- read part of a directory
- remember an offset, and close the directory
- re-open the directory some time later
directory was not created on the upper layer to start with) overlayfs can
handle it in two different ways:
-1) return EXDEV error: this error is returned by rename(2) when trying to
+1. return EXDEV error: this error is returned by rename(2) when trying to
move a file or directory across filesystem boundaries. Hence
applications are usually prepared to hande this error (mv(1) for example
recursively copies the directory tree). This is the default behavior.
-2) If the "redirect_dir" feature is enabled, then the directory will be
+2. If the "redirect_dir" feature is enabled, then the directory will be
copied up (but not the contents). Then the "trusted.overlay.redirect"
extended attribute is set to the path of the original location from the
root of the overlay. Finally the directory is moved to the new