kernel.git/fs/overlayfs/inode.c, branch linux-4.13.y

ovl: fix EIO from lookup of non-indexed upper

2017-11-02T08:54:47Z

commit 6eaf011144af10cad34c0d46f82e50d382c8e926 upstream. Commit fbaf94ee3cd5 ("ovl: don't set origin on broken lower hardlink") attempt to avoid the condition of non-indexed upper inode with lower hardlink as origin. If this condition is found, lookup returns EIO. The protection of commit mentioned above does not cover the case of lower that is not a hardlink when it is copied up (with either index=off/on) and then lower is hardlinked while overlay is offline. Changes to lower layer while overlayfs is offline should not result in unexpected behavior, so a permanent EIO error after creating a link in lower layer should not be considered as correct behavior. This fix replaces EIO error with success in cases where upper has origin but no index is found, or index is found that does not match upper inode. In those cases, lookup will not fail and the returned overlay inode will be hashed by upper inode instead of by lower origin inode. Fixes: 359f392ca53e ("ovl: lookup index entry for copy up origin") Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix false positive ESTALE on lookup

2017-09-20T06:27:48Z

commit 939ae4efd51c627da270af74ef069db5124cb5b0 upstream. Commit b9ac5c274b8c ("ovl: hash overlay non-dir inodes by copy up origin") verifies that the origin lower inode stored in the overlayfs inode matched the inode of a copy up origin dentry found by lookup. There is a false positive result in that check when lower fs does not support file handles and copy up origin cannot be followed by file handle at lookup time. The false negative happens when finding an overlay inode in cache on a copied up overlay dentry lookup. The overlay inode still 'remembers' the copy up origin inode, but the copy up origin dentry is not available for verification. Relax the check in case copy up origin dentry is not available. Fixes: b9ac5c274b8c ("ovl: hash overlay non-dir inodes by copy up...") Reported-by: Jordi Pujol Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix xattr get and set with selinux

2017-07-20T09:08:21Z

inode_doinit_with_dentry() in SELinux wants to read the upper inode's xattr to get security label, and ovl_xattr_get() calls ovl_dentry_real(), which depends on dentry->d_inode, but d_inode is null and not initialized yet at this point resulting in an Oops. Fix by getting the upperdentry info from the inode directly in this case. Reported-by: Eryu Guan Fixes: 09d8b586731b ("ovl: move __upperdentry to ovl_inode") Signed-off-by: Miklos Szeredi

ovl: cleanup orphan index entries

2017-07-04T20:03:19Z

index entry should live only as long as there are upper or lower hardlinks. Cleanup orphan index entries on mount and when dropping the last overlay inode nlink. When about to cleanup or link up to orphan index and the index inode nlink > 1, admit that something went wrong and adjust overlay nlink to index inode nlink - 1 to prevent it from dropping below zero. This could happen when adding lower hardlinks underneath a mounted overlay and then trying to unlink them. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: persistent overlay inode nlink for indexed inodes

2017-07-04T20:03:19Z

With inodes index enabled, an overlay inode nlink counts the union of upper and non-covered lower hardlinks. During the lifetime of a non-pure upper inode, the following nlink modifying operations can happen: 1. Lower hardlink copy up 2. Upper hardlink created, unlinked or renamed over 3. Lower hardlink whiteout or renamed over For the first, copy up case, the union nlink does not change, whether the operation succeeds or fails, but the upper inode nlink may change. Therefore, before copy up, we store the union nlink value relative to the lower inode nlink in the index inode xattr trusted.overlay.nlink. For the second, upper hardlink case, the union nlink should be incremented or decremented IFF the operation succeeds, aligned with nlink change of the upper inode. Therefore, before link/unlink/rename, we store the union nlink value relative to the upper inode nlink in the index inode. For the last, lower cover up case, we simplify things by preceding the whiteout or cover up with copy up. This makes sure that there is an index upper inode where the nlink xattr can be stored before the copied up upper entry is unlink. Return the overlay inode nlinks for indexed upper inodes on stat(2). Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: implement index dir copy up

2017-07-04T20:03:19Z

Implement a copy up method for non-dir objects using index dir to prevent breaking lower hardlinks on copy up. This method requires that the inodes index dir feature was enabled and that all underlying fs support file handle encoding/decoding. On the first lower hardlink copy up, upper file is created in index dir, named after the hex representation of the lower origin inode file handle. On the second lower hardlink copy up, upper file is found in index dir, by the same lower handle key. On either case, the upper indexed inode is then linked to the copy up upper path. The index entry remains linked for future lower hardlink copy up and for lower to upper inode map, that is needed for exporting overlayfs to NFS. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: hash overlay non-dir inodes by copy up origin

2017-07-04T20:03:17Z

Signed-off-by: Miklos Szeredi

ovl: lookup index entry for copy up origin

2017-07-04T20:03:17Z

When inodes index feature is enabled, lookup in indexdir for the index entry of lower real inode or copy up origin inode. The index entry name is the hex representation of the lower inode file handle. If the index dentry in negative, then either no lower aliases have been copied up yet, or aliases have been copied up in older kernels and are not indexed. If the index dentry for a copy up origin inode is positive, but points to an inode different than the upper inode, then either the upper inode has been copied up and not indexed or it was indexed, but since then index dir was cleared. Either way, that index cannot be used to indentify the overlay inode. If a positive dentry that matches the upper inode was found, then it is safe to use the copy up origin st_ino for upper hardlinks, because all indexed upper hardlinks are represented by the same overlay inode as the copy up origin. Set the INDEX type flag on an indexed upper dentry. A non-upper dentry may also have a positive index from copy up of another lower hardlink. This situation will be handled by following patches. Index lookup is going to be used to prevent breaking hardlinks on copy up. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: move impure to ovl_inode

2017-07-04T20:03:16Z

Signed-off-by: Miklos Szeredi

ovl: move __upperdentry to ovl_inode

2017-07-04T20:03:16Z

Signed-off-by: Miklos Szeredi