fs/overlayfs/inode.c

221 			     (is_dir || lowerstat.nlink == 1))) {
268 	 * correct link count.  nlink=1 seems to pacify 'find' and
272 		stat->nlink = 1;
276 	 * Overlay inode nlink counts the union of the upper hardlinks
281 		stat->nlink = dentry->d_inode->i_nlink;
938  * With inodes index enabled, an overlay inode nlink counts the union of upper
940  * upper inode, the following nlink modifying operations can happen:
946  * For the first, copy up case, the union nlink does not change, whether the
947  * operation succeeds or fails, but the upper inode nlink may change.
948  * Therefore, before copy up, we store the union nlink value relative to the
949  * lower inode nlink in the index inode xattr .overlay.nlink.
951  * For the second, upper hardlink case, the union nlink should be incremented
952  * or decremented IFF the operation succeeds, aligned with nlink change of the
953  * upper inode. Therefore, before link/unlink/rename, we store the union nlink
954  * value relative to the upper inode nlink in the index inode.
958  * upper inode where the nlink xattr can be stored before the copied up upper
964  * On-disk format for indexed nlink:
966  * nlink relative to the upper inode - "U[+-]NUM"
967  * nlink relative to the lower inode - "L[+-]NUM"
1003 	int nlink;
1024 	nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink;
1025 	nlink += nlink_diff;
1027 	if (nlink <= 0)
1030 	return nlink;
1033 	pr_warn_ratelimited("failed to get index nlink (%pd2, err=%i)\n",
1237 		unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
1261 		/* Recalculate nlink for non-dir due to indexing */
1263 			nlink = ovl_get_nlink(ofs, lowerdentry, upperdentry,
1264 					      nlink);
1265 		set_nlink(inode, nlink);