kernel.git/fs/overlayfs/inode.c, branch linux-4.16.y

ovl: set lower layer st_dev only if setting lower st_ino

2018-04-19T06:54:09Z

commit 9f99e50d460ac7fd5f6c9b97aad0088c28c8656d upstream. For broken hardlinks, we do not return lower st_ino, so we should also not return lower pseudo st_dev. Fixes: a0c5ad307ac0 ("ovl: relax same fs constraint for constant st_ino") Cc: #v4.15 Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: set i_ino to the value of st_ino for NFS export

2018-04-19T06:54:09Z

commit 695b46e76b62447e506cddc87e088236498008e5 upstream. Eddie Horng reported that readdir of an overlayfs directory that was exported via NFSv3 returns entries with d_type set to DT_UNKNOWN. The reason is that while preparing the response for readdirplus, nfsd checks inside encode_entryplus_baggage() that a child dentry's inode number matches the value of d_ino returns by overlayfs readdir iterator. Because the overlayfs inodes use arbitrary inode numbers that are not correlated with the values of st_ino/d_ino, NFSv3 falls back to not encoding d_type. Although this is an allowed behavior, we can fix it for the case of all overlayfs layers on the same underlying filesystem. When NFS export is enabled and d_ino is consistent with st_ino (samefs), set the same value also to i_ino in ovl_fill_inode() for all overlayfs inodes, nfsd readdirplus sanity checks will pass. ovl_fill_inode() may be called from ovl_new_inode(), before real inode was created with ino arg 0. In that case, i_ino will be updated to real upper inode i_ino on ovl_inode_init() or ovl_inode_update(). Reported-by: Eddie Horng Tested-by: Eddie Horng Signed-off-by: Amir Goldstein Fixes: 8383f1748829 ("ovl: wire up NFS export operations") Cc: #v4.16 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: hash non-dir by lower inode for fsnotify

2018-02-16T14:53:20Z

Commit 31747eda41ef ("ovl: hash directory inodes for fsnotify") fixed an issue of inotify watch on directory that stops getting events after dropping dentry caches. A similar issue exists for non-dir non-upper files, for example: $ mkdir -p lower upper work merged $ touch lower/foo $ mount -t overlay -o lowerdir=lower,workdir=work,upperdir=upper none merged $ inotifywait merged/foo & $ echo 2 > /proc/sys/vm/drop_caches $ cat merged/foo inotifywait doesn't get the OPEN event, because ovl_lookup() called from 'cat' allocates a new overlay inode and does not reuse the watched inode. Fix this by hashing non-dir overlay inodes by lower real inode in the following cases that were not hashed before this change: - A non-upper overlay mount - A lower non-hardlink when index=off A helper ovl_hash_bylower() was added to put all the logic and documentation about which real inode an overlay inode is hashed by into one place. The issue dates back to initial version of overlayfs, but this patch depends on ovl_inode code that was introduced in kernel v4.13. Cc: #v4.13 Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: lookup connected ancestor of dir in inode cache

2018-01-24T10:26:05Z

Decoding a dir file handle requires walking backward up to layer root and for lower dir also checking the index to see if any of the parents have been copied up. Lookup overlay ancestor dentry in inode/dentry cache by decoded real parents to shortcut looking up all the way back to layer root. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: hash non-indexed dir by upper inode for NFS export

2018-01-24T10:26:04Z

Non-indexed upper dirs are encoded as upper file handles. When NFS export is enabled, hash non-indexed directory inodes by upper inode, so we can find them in inode cache using the decoded upper inode. When NFS export is disabled, directories are not indexed on copy up, so hash non-indexed directory inodes by origin inode, the same hash key that is used before copy up. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: decode lower file handles of unlinked but open files

2018-01-24T10:26:03Z

Lookup overlay inode in cache by origin inode, so we can decode a file handle of an open file even if the index has a whiteout index entry to mark this overlay inode was unlinked. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: copy up of disconnected dentries

2018-01-24T10:25:58Z

With NFS export, some operations on decoded file handles (e.g. open, link, setattr, xattr_set) may call copy up with a disconnected non-dir. In this case, we will copy up lower inode to index dir without linking it to upper dir. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: do not pass overlay dentry to ovl_get_inode()

2018-01-24T10:25:57Z

This is needed for using ovl_get_inode() for decoding file handles for NFS export. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: unbless lower st_ino of unverified origin

2018-01-24T10:25:52Z

On a malformed overlay, several redirected dirs can point to the same dir on a lower layer. This presents a similar challenge as broken hardlinks, because different objects in the overlay can return the same st_ino/st_dev pair from stat(2). For broken hardlinks, we do not provide constant st_ino on copy up to avoid this inconsistency. When NFS export feature is enabled, apply the same logic to files and directories with unverified lower origin. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: hash directory inodes for fsnotify

2018-01-19T12:54:33Z

fsnotify pins a watched directory inode in cache, but if directory dentry is released, new lookup will allocate a new dentry and a new inode. Directory events will be notified on the new inode, while fsnotify listener is watching the old pinned inode. Hash all directory inodes to reuse the pinned inode on lookup. Pure upper dirs are hashes by real upper inode, merge and lower dirs are hashed by real lower inode. The reference to lower inode was being held by the lower dentry object in the overlay dentry (oe->lowerstack[0]). Releasing the overlay dentry may drop lower inode refcount to zero. Add a refcount on behalf of the overlay inode to prevent that. As a by-product, hashing directory inodes also detects multiple redirected dirs to the same lower dir and uncovered redirected dir target on and returns -ESTALE on lookup. The reported issue dates back to initial version of overlayfs, but this patch depends on ovl_inode code that was introduced in kernel v4.13. Cc: #v4.13 Reported-by: Niklas Cassel Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Tested-by: Niklas Cassel