ovl: update documentation of inodes index feature

Document that inode index feature solves breaking hard links on
copy up.

Simplify Kconfig backward compatibility disclaimer.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt
index e6a5f4912b6d4a4910ed1d2fc494fff304ab47ff..213547cb6d361b3513b2b7be6f99d508827bd747 100644 (file)
--- a/Documentation/filesystems/overlayfs.txt
+++ b/Documentation/filesystems/overlayfs.txt
@@ -281,9 +281,9 @@ filesystem, so both st_dev and st_ino of the file may change.
 
 Any open files referring to this inode will access the old data.
 
-If a file with multiple hard links is copied up, then this will
-"break" the link.  Changes will not be propagated to other names
-referring to the same inode.
+Unless "inode index" feature is enabled, if a file with multiple hard
+links is copied up, then this will "break" the link.  Changes will not be
+propagated to other names referring to the same inode.
 
 Unless "redirect_dir" feature is enabled, rename(2) on a lower or merged
 directory will fail with EXDEV.

diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
index 5ac4154668613d158d63301272039ee5f5b814e4..9eac01c3e21efb0a01721c1ade51f07a73c6e257 100644 (file)
--- a/fs/overlayfs/Kconfig
+++ b/fs/overlayfs/Kconfig
@@ -47,9 +47,6 @@ config OVERLAY_FS_INDEX
          The inodes index feature prevents breaking of lower hardlinks on copy
          up.
 
-         Note, that the inodes index feature is read-only backward compatible.
-         That is, mounting an overlay which has an index dir on a kernel that
-         doesn't support this feature read-only, will not have any negative
-         outcomes.  However, mounting the same overlay with an old kernel
-         read-write and then mounting it again with a new kernel, will have
-         unexpected results.
+         Note, that the inodes index feature is not backward compatible.
+         That is, mounting an overlay which has an inodes index on a kernel
+         that doesn't support this feature will have unexpected results.