Merge tag 'ovl-fixes-5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "Here's one fix for a class of bugs triggered by syzcaller, and one
  that makes xfstests fail less"

* tag 'ovl-fixes-5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: doc: add non-standard corner cases
  ovl: detect overlapping layers
  ovl: support the FS_IOC_FS[SG]ETXATTR ioctls

1 files changed, 14 insertions, 2 deletions

diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt
index eef7d9d259e8..1da2f1668f08 100644
--- a/Documentation/filesystems/overlayfs.txt
+++ b/Documentation/filesystems/overlayfs.txt
@@ -336,8 +336,20 @@ the copied layers will fail the verification of the lower root file handle.
 Non-standard behavior
 ---------------------
 
-Overlayfs can now act as a POSIX compliant filesystem with the following
-features turned on:
+Current version of overlayfs can act as a mostly POSIX compliant
+filesystem.
+
+This is the list of cases that overlayfs doesn't currently handle:
+
+a) POSIX mandates updating st_atime for reads.  This is currently not
+done in the case when the file resides on a lower layer.
+
+b) If a file residing on a lower layer is opened for read-only and then
+memory mapped with MAP_SHARED, then subsequent changes to the file are not
+reflected in the memory mapping.
+
+The following options allow overlayfs to act more like a standards
+compliant filesystem:
 
 1) "redirect_dir"