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 <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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 <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Move ovl_copy_up_start()/ovl_copy_up_end() out so that it's used for both
tempfile and workdir copy ups.
Signed-off-by: Miklos 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: Miklos Szeredi <mszeredi@redhat.com>
Factor out helper for copying lower inode data and metadata to temp
upper inode, that is common to copy up using O_TMPFILE and workdir.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
On copy up of regular file using an O_TMPFILE, lock upper dir only
before linking the tempfile in place.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pass in the subdir name to create and specify if subdir is persistent
or if it should be cleaned up on every mount.
Move fallback to readonly mount on failure to create dir and print of error
message into the helper.
This function is going to be used for creating the persistent 'index' dir
under workbasedir.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
For the case of all layers not on the same fs, try to decode the copy up
origin file handle on any of the lower layers.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Bad things can happen if several concurrent overlay mounts try to
use the same upperdir/workdir path.
Try to get the 'inuse' advisory lock on upperdir and workdir.
Fail mount if another overlay mount instance or another user
holds the 'inuse' lock on these directories.
Note that this provides no protection for concurrent overlay
mount that use overlapping (i.e. descendant) upper/work dirs.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Use the new ovl_inode mutex to synchonize concurrent copy up
instead of the super block copy up workqueue.
Moving the synchronization object from the overlay dentry to
the overlay inode is needed for synchonizing concurrent copy up
of lower hardlinks to the same upper inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When checking for consistency in directory operations (unlink, rename,
etc.) match inodes not dentries.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
We need some more space to store overlay inode data in memory,
so allocate overlay inodes from a slab of struct ovl_inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This patch fixes an overlay inode nlink leak in the case where
ovl_rename() renames over a non-dir.
This is not so critical, because overlay inode doesn't rely on
nlink dropping to zero for inode deletion.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
- introduce the new uuid_t/guid_t types that are going to replace
the somewhat confusing uuid_be/uuid_le types and make the terminology
fit the various specs, as well as the userspace libuuid library.
(me, based on a previous version from Amir)
- consolidated generic uuid/guid helper functions lifted from XFS
and libnvdimm (Amir and me)
- conversions to the new types and helpers (Amir, Andy and me)
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Merge tag 'uuid-for-4.13' of git://git.infradead.org/users/hch/uuid into overlayfs-next
UUID/GUID updates:
- introduce the new uuid_t/guid_t types that are going to replace
the somewhat confusing uuid_be/uuid_le types and make the terminology
fit the various specs, as well as the userspace libuuid library.
(me, based on a previous version from Amir)
- consolidated generic uuid/guid helper functions lifted from XFS
and libnvdimm (Amir and me)
- conversions to the new types and helpers (Amir, Andy and me)
When copying up a file that has multiple hard links we need to break any
association with the origin file. This makes copy-up be essentially an
atomic replace.
The new file has nothing to do with the old one (except having the same
data and metadata initially), so don't set the overlay.origin attribute.
We can relax this in the future when we are able to index upper object by
origin.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 3a1e819b4e ("ovl: store file handle of lower inode on copy up")
Nothing prevents mischief on upper layer while we are busy copying up the
data.
Move the lookup right before the looked up dentry is actually used.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 01ad3eb8a0 ("ovl: concurrent copy up of regular files")
Cc: <stable@vger.kernel.org> # v4.11
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
For some file systems we still memcpy into it, but in various places this
already allows us to use the proper uuid helpers. More to come..
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com> (Changes to IMA/EVM)
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Filesystems filter out extended attributes in the "trusted." domain for
unprivlieged callers.
Overlay calls underlying filesystem's method with elevated privs, so need
to do the filtering in overlayfs too.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
We get a link error when EXPORTFS is not enabled:
ERROR: "exportfs_encode_fh" [fs/overlayfs/overlay.ko] undefined!
ERROR: "exportfs_decode_fh" [fs/overlayfs/overlay.ko] undefined!
This adds a Kconfig 'select' statement for overlayfs, the same way that
it is done for the other users of exportfs.
Fixes: 3a1e819b4e ("ovl: store file handle of lower inode on copy up")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pull overlayfs update from Miklos Szeredi:
"The biggest part of this is making st_dev/st_ino on the overlay behave
like a normal filesystem (i.e. st_ino doesn't change on copy up,
st_dev is the same for all files and directories). Currently this only
works if all layers are on the same filesystem, but future work will
move the general case towards more sane behavior.
There are also miscellaneous fixes, including fixes to handling
append-only files. There's a small change in the VFS, but that only
has an effect on overlayfs, since otherwise file->f_path.dentry->inode
and file_inode(file) are always the same"
* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: update documentation w.r.t. constant inode numbers
ovl: persistent inode numbers for upper hardlinks
ovl: merge getattr for dir and nondir
ovl: constant st_ino/st_dev across copy up
ovl: persistent inode number for directories
ovl: set the ORIGIN type flag
ovl: lookup non-dir copy-up-origin by file handle
ovl: use an auxiliary var for overlay root entry
ovl: store file handle of lower inode on copy up
ovl: check if all layers are on the same fs
ovl: do not set overlay.opaque on non-dir create
ovl: check IS_APPEND() on real upper inode
vfs: ftruncate check IS_APPEND() on real upper inode
ovl: Use designated initializers
ovl: lockdep annotate of nested stacked overlayfs inode lock
An upper type non directory dentry that is a copy up target
should have a reference to its lower copy up origin.
There are three ways for an upper type dentry to be instantiated:
1. A lower type dentry that is being copied up
2. An entry that is found in upper dir by ovl_lookup()
3. A negative dentry is hardlinked to an upper type dentry
In the first case, the lower reference is set before copy up.
In the second case, the lower reference is found by ovl_lookup().
In the last case of hardlinked upper dentry, it is not easy to
update the lower reference of the negative dentry. Instead,
drop the newly hardlinked negative dentry from dcache and let
the next access call ovl_lookup() to find its lower reference.
This makes sure that the inode number reported by stat(2) after
the hardlink is created is the same inode number that will be
reported by stat(2) after mount cycle, which is the inode number
of the lower copy up origin of the hardlink source.
NOTE that this does not fix breaking of lower hardlinks on copy
up, but only fixes the case of lower nlink == 1, whose upper copy
up inode is hardlinked in upper dir.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When all layers are on the same underlying filesystem, let stat(2) return
st_dev/st_ino values of the copy up origin inode if it is known.
This results in constant st_ino/st_dev representation of files in an
overlay mount before and after copy up.
When the underlying filesystem support NFS exportfs, the result is also
persistent st_ino/st_dev representation before and after mount cycle.
Lower hardlinks are 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.
When all overlay layers are on the same fs, use overlay st_dev for non-dirs
to get the correct result from du -x.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Amir Goldstein
Miklos Szeredi
Christoph Hellwig
Arnd Bergmann
Linus Torvalds