[v2,20/20] ovl: constant inode number for hardlinks

Commit Message

Amir Goldstein June 7, 2017, 7:51 a.m. UTC

When inodes index feature is enabled, it is safe to return the copy up
origin st_ino for indexed upper hardlinks, because all indexed upper
hardlinks are represented by the same overlay inode as the copy up
origin.

Signed-off-by: Amir Goldstein <[e-mail]>
---
 fs/overlayfs/inode.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Patch

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 6e85a2a7fcdc..8a30dc6cd42d 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -96,11 +96,14 @@  int ovl_getattr(const struct path *path, struct kstat *stat,
 
 			WARN_ON_ONCE(stat->dev != lowerstat.dev);
 			/*
-			 * Lower hardlinks are broken on copy up to different
+			 * Lower hardlinks may be broken on copy up to different
 			 * upper files, so we cannot use the lower origin st_ino
 			 * for those different files, even for the same fs case.
+			 * Indexed upper inodes are safe and non-hardlinked
+			 * origin inodes are safe.
 			 */
-			if (is_dir || lowerstat.nlink == 1)
+			if (is_dir || lowerstat.nlink == 1 ||
+			    OVL_TYPE_INDEX(type))
 				stat->ino = lowerstat.ino;
 		}
 		stat->dev = dentry->d_sb->s_dev;