Merge tag 'ovl-update-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs updates from Miklos Szeredi:
 "Fixes:

   - Resolve mount option conflicts consistently

   - Sync before remount R/O

   - Fix file handle encoding corner cases

   - Fix metacopy related issues

   - Fix an unintialized return value

   - Add missing permission checks for underlying layers

  Optimizations:

   - Allow multipe whiteouts to share an inode

   - Optimize small writes by inheriting SB_NOSEC from upper layer

   - Do not call ->syncfs() multiple times for sync(2)

   - Do not cache negative lookups on upper layer

   - Make private internal mounts longterm"

* tag 'ovl-update-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (27 commits)
  ovl: remove unnecessary lock check
  ovl: make oip->index bool
  ovl: only pass ->ki_flags to ovl_iocb_to_rwf()
  ovl: make private mounts longterm
  ovl: get rid of redundant members in struct ovl_fs
  ovl: add accessor for ofs->upper_mnt
  ovl: initialize error in ovl_copy_xattr
  ovl: drop negative dentry in upper layer
  ovl: check permission to open real file
  ovl: call secutiry hook in ovl_real_ioctl()
  ovl: verify permissions in ovl_path_open()
  ovl: switch to mounter creds in readdir
  ovl: pass correct flags for opening real directory
  ovl: fix redirect traversal on metacopy dentries
  ovl: initialize OVL_UPPERDATA in ovl_lookup()
  ovl: use only uppermetacopy state in ovl_lookup()
  ovl: simplify setting of origin for index lookup
  ovl: fix out of bounds access warning in ovl_check_fb_len()
  ovl: return required buffer size for file handles
  ovl: sync dirty data when remounting to ro mode
  ...

2 files changed, 12 insertions, 2 deletions

diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
index c9d2bf96b02d..660dbaf0b9b8 100644
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -365,8 +365,8 @@ pointed by REDIRECT. This should not be possible on local system as setting
 "trusted." xattrs will require CAP_SYS_ADMIN. But it should be possible
 for untrusted layers like from a pen drive.
 
-Note: redirect_dir={off|nofollow|follow[*]} conflicts with metacopy=on, and
-results in an error.
+Note: redirect_dir={off|nofollow|follow[*]} and nfs_export=on mount options
+conflict with metacopy=on, and will result in an error.
 
 [*] redirect_dir=follow only conflicts with metacopy=on if upperdir=... is
 given.
@@ -560,6 +560,9 @@ When the NFS export feature is enabled, all directory index entries are
 verified on mount time to check that upper file handles are not stale.
 This verification may cause significant overhead in some cases.
 
+Note: the mount options index=off,nfs_export=on are conflicting and will
+result in an error.
+
 
 Testsuite
 ---------
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index 26c093969573..867036aa90b8 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -858,3 +858,10 @@ be misspelled d_alloc_anon().
 [should've been added in 2016] stale comment in finish_open() nonwithstanding,
 failure exits in ->atomic_open() instances should *NOT* fput() the file,
 no matter what.  Everything is handled by the caller.
+
+---
+
+**mandatory**
+
+clone_private_mount() returns a longterm mount now, so the proper destructor of
+its result is kern_unmount() or kern_unmount_array().