The helper is needed to lookup an index by file handle for NFS export.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

With NFS export feature enabled, when overlay inode nlink drops to
zero, instead of removing the index entry, replace it with a whiteout
index entry.

This is needed for NFS export in order to prevent future open by handle
from opening the lower file directly.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

The helper determines which lower file needs to be indexed
on copy up and before nlink changes.

For index=on, the helper evaluates to true for lower hardlinks.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

A directory index is a directory type entry in index dir with a
"trusted.overlay.upper" xattr containing an encoded ovl_fh of the merge
directory upper dir inode.

On lookup of non-dir files, lower file is followed by origin file handle.
On lookup of dir entries, lower dir is found by name and then compared
to origin file handle. We only trust dir index if we verified that lower
dir matches origin file handle, otherwise index may be inconsistent and
we ignore it.

If we find an indexed non-upper dir or an indexed merged dir, whose
index 'upper' xattr points to a different upper dir, that means that the
lower directory may be also referenced by another upper dir via redirect,
so we fail the lookup on inconsistency error.

To be consistent with directory index entries format, the association of
index dir to upper root dir, that was stored by older kernels in
"trusted.overlay.origin" xattr is now stored in "trusted.overlay.upper"
xattr. This also serves as an indication that overlay was mounted with a
kernel that support index directory entries. For backward compatibility,
if an 'origin' xattr exists on the index dir we also verify it on mount.

Directory index entries are going to be used for NFS export.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Introduce the "nfs_export" config, module and mount options.

The NFS export feature depends on the "index" feature and enables two
implicit overlayfs features: "index_all" and "verify_lower".
The "index_all" feature creates an index on copy up of every file and
directory. The "verify_lower" feature uses the full index to detect
overlay filesystems inconsistencies on lookup, like redirect from
multiple upper dirs to the same lower dir.

NFS export can be enabled for non-upper mount with no index. However,
because lower layer redirects cannot be verified with the index, enabling
NFS export support on an overlay with no upper layer requires turning off
redirect follow (e.g. "redirect_dir=nofollow").

The full index may incur some overhead on mount time, especially when
verifying that lower directory file handles are not stale.

NFS export support, full index and consistency verification will be
implemented by following patches.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Remove the "origin" language from the functions that handle set, get
and verify of "origin" xattr and pass the xattr name as an argument.

The same helpers are going to be used for NFS export to get, get and
verify the "upper" xattr for directory index entries.

ovl_verify_origin() is now a helper used only to verify non upper
file handle stored in "origin" xattr of upper inode.

The upper root dir file handle is still stored in "origin" xattr on
the index dir for backward compatibility. This is going to be changed
by the patch that adds directory index entries support.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Pass the fs instance with lower_layers array instead of the dentry
lowerstack array to ovl_check_origin_fh(), because the dentry members
of lowerstack play no role in this helper.

This change simplifies the argument list of ovl_check_origin(),
ovl_cleanup_index() and ovl_verify_index().
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

For a merge dir that was copied up before v4.12 or that was hand crafted
offline (e.g. mkdir {upper/lower}/dir), upper dir does not contain the
'trusted.overlay.origin' xattr.  In that case, stat(2) on the merge dir
returns the lower dir st_ino, but getdents(2) returns the upper dir d_ino.

After this change, on merge dir lookup, missing origin xattr on upper
dir will be fixed and 'impure' xattr will be fixed on parent of the legacy
merge dir.
Suggested-by: Nzhangyi (F) <yi.zhang@huawei.com>
Reviewed-by: Nzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Fix ptr_ret.cocci warnings:
fs/overlayfs/overlayfs.h:179:11-17: WARNING: PTR_ERR_OR_ZERO can be used

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci
Signed-off-by: NVasyl Gomonovych <gomonovych@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

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

Define new structures to represent overlay instance lower layers and
overlay merge dir lower layers to make room for storing more per layer
information in-memory.

Instead of keeping the fs instance lower layers in an array of struct
vfsmount, keep them in an array of new struct ovl_layer, that has a
pointer to struct vfsmount.

Instead of keeping the dentry lower layers in an array of struct path,
keep them in an array of new struct ovl_path, that has a pointer to
struct dentry and to struct ovl_layer.

Add a small helper to find the fs layer id that correspopnds to a lower
struct ovl_path and use it in ovl_lookup().

[amir: split re-structure from anonymous bdev patch]
Signed-off-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Most overlayfs c files already explicitly include ovl_entry.h
to use overlay entry struct definitions and upcoming changes
are going to require even more c files to include this header.

All overlayfs c files include overlayfs.h and overlayfs.h itself
refers to some structs defined in ovl_entry.h, so it seems more
logic to include ovl_entry.h from overlayfs.h than from c files.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

If a non-merge dir in an overlay mount has an overlay.origin xattr, it
means it was once an upper merge dir, which may contain whiteouts and
then the lower dir was removed under it.

Do not iterate real dir directly in this case to avoid exposing whiteouts.

[SzM] Set OVL_WHITEOUT for all merge directories as well.

[amir] A directory that was just copied up does not have the OVL_WHITEOUTS
flag. We need to set it to fix merge dir iteration.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Commit fbaf94ee ("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: 359f392c ("ovl: lookup index entry for copy up origin")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Use the ovl_lock_rename_workdir() helper which requires
unlock_rename() only on lock success.

Fixes: ("fd210b7d ovl: move copy up lock out")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Impure directories are ones which contain objects with origins (i.e. those
that have been copied up).  These are relevant to readdir operation only
because of the d_ino field, no other transformation is necessary.  Also a
directory can become impure between two getdents(2) calls.

This patch creates a cache for impure directories.  Unlike the cache for
merged directories, this one only contains entries with origin and is not
refcounted but has a its lifetime tied to that of the dentry.

Similarly to the merged cache, the impure cache is invalidated based on a
version number.  This version number is incremented when an entry with
origin is added or removed from the directory.

If the cache is empty, then the impure xattr is removed from the directory.

This patch also fixes up handling of d_ino for the ".." entry if the parent
directory is merged.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

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: NEryu Guan <eguan@redhat.com>
Fixes: 09d8b586 ("ovl: move __upperdentry to ovl_inode")
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Commit 54fb347e ("ovl: verify index dir matches upper dir")
introduced a new ovl_fh flag OVL_FH_FLAG_PATH_UPPER to indicate
an upper file handle, but forgot to add the flag to the mask of
valid flags, so index dir origin verification always discards
existing origin and stores a new one.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

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

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

For rename, we need to ensure that an upper alias exists for hard links
before attempting the operation.  Introduce a flag in ovl_entry to track
the state of the upper alias.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Bad index entries are entries whose name does not match the
origin file handle stored in trusted.overlay.origin xattr.
Bad index entries could be a result of a system power off in
the middle of copy up.

Stale index entries are entries whose origin file handle is
stale. Stale index entries could be a result of copying layers
or removing lower entries while the overlay is not mounted.
The case of copying layers should be detected earlier by the
verification of upper root dir origin and index dir origin.

Both bad and stale index entries are detected and removed
on mount.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

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

An index dir contains persistent hardlinks to files in upper dir.
Therefore, we must never mount an existing index dir with a differnt
upper dir.

Store the upper root dir file handle in index dir inode when index
dir is created and verify the file handle before using an existing
index dir on mount.

Add an 'is_upper' flag to the overlay file handle encoding and set it
when encoding the upper root file handle. This is not critical for index
dir verification, but it is good practice towards a standard overlayfs
file handle format for NFS export.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

When inodes index feature is enabled, verify that the file handle stored
in upper root dir matches the lower root dir or fail to mount.

If upper root dir has no stored file handle, encode and store the lower
root dir file handle in overlay.origin xattr.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Create the index dir on mount. The index dir will contain hardlinks to
upper inodes, named after the hex representation of their origin lower
inodes.

The index dir is going to be used to prevent breaking lower hardlinks
on copy up and to implement overlayfs NFS export.

Because the feature is not fully backward compat, enabling the feature
is opt-in by config/module/mount option.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Added an i_state flag I_INUSE and helpers to set/clear/test the bit.

The 'inuse' lock is an 'advisory' inode lock, that can be used to extend
exclusive create protection beyond parent->i_mutex lock among cooperating
users.

This is going to be used by overlayfs to get exclusive ownership on upper
and work dirs among overlayfs mounts.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAmir Goldstein <amir73il@gmail.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

An upper dir is marked "impure" to let ovl_iterate() know that this
directory may contain non pure upper entries whose d_ino may need to be
read from the origin inode.

We already mark a non-merge dir "impure" when moving a non-pure child
entry inside it, to let ovl_iterate() know not to iterate the non-merge
dir directly.

Mark also a merge dir "impure" when moving a non-pure child entry inside
it and when copying up a child entry inside it.

This can be used to optimize ovl_iterate() to perform a "pure merge" of
upper and lower directories, merging the content of the directories,
without having to read d_ino from origin inodes.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

When moving a merge dir or non-dir with copy up origin into a non-merge
upper dir (a.k.a pure upper dir), we are marking the target parent dir
"impure". ovl_iterate() iterates pure upper dirs directly, because there is
no need to filter out whiteouts and merge dir content with lower dir. But
for the case of an "impure" upper dir, ovl_iterate() will not be able to
iterate the real upper dir directly, because it will need to lookup the
origin inode and use it to fill d_ino.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

On failure to set opaque/redirect xattr on rename, skip setting xattr and
return -EXDEV.

On failure to set opaque xattr when creating a new directory, -EIO is
returned instead of -EOPNOTSUPP.

Any failure to set those xattr will be recorded in super block and
then setting any xattr on upper won't be attempted again.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

xattr are needed by overlayfs for setting opaque dir, redirect dir
and copy up origin.

Check at mount time by trying to set the overlay.opaque xattr on the
workdir and if that fails issue a warning message.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

For directory entries, non zero oe->numlower implies OVL_TYPE_MERGE.
Define a new type flag OVL_TYPE_ORIGIN to indicate that an entry holds a
reference to its lower copy up origin.

For directory entries ORIGIN := MERGE && UPPER. For non-dir entries ORIGIN
means that a lower type dentry has been recently copied up or that we were
able to find the copy up origin from overlay.origin xattr.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Sometimes it is interesting to know if an upper file is pure upper or a
copy up target, and if it is a copy up target, it may be interesting to
find the copy up origin.

This will be used to preserve lower inode numbers across copy up.

Store the lower inode file handle in upper inode extended attribute
overlay.origin on copy up to use it later for these cases.  Store the lower
filesystem uuid along side the file handle, so we can validate that we are
looking for the origin file in the original fs.

If lower fs does not support NFS export ops store a zero sized xattr so we
can always use the overlay.origin xattr to distinguish between a copy up
and a pure upper inode.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>