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>
stat(2) on overlay directories reports the overlay temp inode
number, which is constant across copy up, but is not persistent.
When all layers are on the same fs, report the copy up origin inode
number for directories.
This inode number is persistent, unique across the overlay mount and
constant across copy up.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If overlay.origin xattr is found on a non-dir upper inode try to get lower
dentry by calling exportfs_decode_fh().
On failure to lookup by file handle to lower layer, do not lookup the copy
up origin by name, because the lower found by name could be another file in
case the upper file was renamed.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos 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: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Some features can only work when all layers are on the same fs. Test this
condition during mount time, so features can check them later.
Add helper ovl_same_sb() to return the common super block in case all
layers are on the same fs.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The optimization for opaque dir create was wrongly being applied
also to non-dir create.
Fixes: 97c684cc91 ("ovl: create directories inside merged parent opaque")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v4.10
For overlay file open, check IS_APPEND() on the real upper inode
inside d_real(), because the overlay inode does not have the
S_APPEND flag and IS_APPEND() can only be checked at open time.
Note that because overlayfs does not copy up the chattr inode flags
(i.e. S_APPEND, S_IMMUTABLE), the IS_APPEND() check is only relevant
for upper inodes that were set with chattr +a and not to lower
inodes that had chattr +a before copy up.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Prepare to mark sensitive kernel structures for randomization by making
sure they're using designated initializers. These were identified during
allyesconfig builds of x86, arm, and arm64, with most initializer fixes
extracted from grsecurity.
For these cases, use { }, which will be zero-filled, instead of
undesignated NULLs.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This removes the extra include header file that was added in commit
e58bc92783 "Pull overlayfs updates from Miklos Szeredi" now that it
is no longer needed.
There are probably other such includes that got added during the
scheduler header splitup series, but this is the one that annoyed me
personally and I know about.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
An overlayfs instance can be the lower layer of another overlayfs
instance. This setup triggers a lockdep splat of possible recursive
locking of sb->s_type->i_mutex_key in iterate_dir(). Trimmed snip:
[ INFO: possible recursive locking detected ]
bash/2468 is trying to acquire lock:
&sb->s_type->i_mutex_key#14, at: iterate_dir+0x7d/0x15c
but task is already holding lock:
&sb->s_type->i_mutex_key#14, at: iterate_dir+0x7d/0x15c
One problem observed with this splat is that ovl_new_inode()
does not call lockdep_annotate_inode_mutex_key() to annotate
the dir inode lock as &sb->s_type->i_mutex_dir_key like other
fs do.
The other problem is that the 2 nested levels of overlayfs inode
lock are annotated using the same key, which is the cause of the
false positive lockdep warning.
Fix this by annotating overlayfs inode lock in ovl_fill_inode()
according to stack level of the super block instance and use
different key for dir vs. non-dir like other fs do.
Here is an edited snip from /proc/lockdep_chains after
iterate_dir() of nested overlayfs:
[...] &ovl_i_mutex_dir_key[depth] (stack_depth=2)
[...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1)
[...] &type->i_mutex_dir_key (stack_depth=0)
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pull overlayfs updates from Miklos Szeredi:
"Because copy up can take a long time, serialized copy ups could be a
big performance bottleneck. This update allows concurrent copy up of
regular files eliminating this potential problem.
There are also minor fixes"
* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: drop CAP_SYS_RESOURCE from saved mounter's credentials
ovl: properly implement sync_filesystem()
ovl: concurrent copy up of regular files
ovl: introduce copy up waitqueue
ovl: copy up regular file using O_TMPFILE
ovl: rearrange code in ovl_copy_up_locked()
ovl: check if upperdir fs supports O_TMPFILE
Pull vfs 'statx()' update from Al Viro.
This adds the new extended stat() interface that internally subsumes our
previous stat interfaces, and allows user mode to specify in more detail
what kind of information it wants.
It also allows for some explicit synchronization information to be
passed to the filesystem, which can be relevant for network filesystems:
is the cached value ok, or do you need open/close consistency, or what?
From David Howells.
Andreas Dilger points out that the first version of the extended statx
interface was posted June 29, 2010:
https://www.spinics.net/lists/linux-fsdevel/msg33831.html
* 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
statx: Add a system call to make enhanced file info available
Add a system call to make extended file information available, including
file creation and some attribute flags where available through the
underlying filesystem.
The getattr inode operation is altered to take two additional arguments: a
u32 request_mask and an unsigned int flags that indicate the
synchronisation mode. This change is propagated to the vfs_getattr*()
function.
Functions like vfs_stat() are now inline wrappers around new functions
vfs_statx() and vfs_statx_fd() to reduce stack usage.
========
OVERVIEW
========
The idea was initially proposed as a set of xattrs that could be retrieved
with getxattr(), but the general preference proved to be for a new syscall
with an extended stat structure.
A number of requests were gathered for features to be included. The
following have been included:
(1) Make the fields a consistent size on all arches and make them large.
(2) Spare space, request flags and information flags are provided for
future expansion.
(3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an
__s64).
(4) Creation time: The SMB protocol carries the creation time, which could
be exported by Samba, which will in turn help CIFS make use of
FS-Cache as that can be used for coherency data (stx_btime).
This is also specified in NFSv4 as a recommended attribute and could
be exported by NFSD [Steve French].
(5) Lightweight stat: Ask for just those details of interest, and allow a
netfs (such as NFS) to approximate anything not of interest, possibly
without going to the server [Trond Myklebust, Ulrich Drepper, Andreas
Dilger] (AT_STATX_DONT_SYNC).
(6) Heavyweight stat: Force a netfs to go to the server, even if it thinks
its cached attributes are up to date [Trond Myklebust]
(AT_STATX_FORCE_SYNC).
And the following have been left out for future extension:
(7) Data version number: Could be used by userspace NFS servers [Aneesh
Kumar].
Can also be used to modify fill_post_wcc() in NFSD which retrieves
i_version directly, but has just called vfs_getattr(). It could get
it from the kstat struct if it used vfs_xgetattr() instead.
(There's disagreement on the exact semantics of a single field, since
not all filesystems do this the same way).
(8) BSD stat compatibility: Including more fields from the BSD stat such
as creation time (st_btime) and inode generation number (st_gen)
[Jeremy Allison, Bernd Schubert].
(9) Inode generation number: Useful for FUSE and userspace NFS servers
[Bernd Schubert].
(This was asked for but later deemed unnecessary with the
open-by-handle capability available and caused disagreement as to
whether it's a security hole or not).
(10) Extra coherency data may be useful in making backups [Andreas Dilger].
(No particular data were offered, but things like last backup
timestamp, the data version number and the DOS archive bit would come
into this category).
(11) Allow the filesystem to indicate what it can/cannot provide: A
filesystem can now say it doesn't support a standard stat feature if
that isn't available, so if, for instance, inode numbers or UIDs don't
exist or are fabricated locally...
(This requires a separate system call - I have an fsinfo() call idea
for this).
(12) Store a 16-byte volume ID in the superblock that can be returned in
struct xstat [Steve French].
(Deferred to fsinfo).
(13) Include granularity fields in the time data to indicate the
granularity of each of the times (NFSv4 time_delta) [Steve French].
(Deferred to fsinfo).
(14) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags.
Note that the Linux IOC flags are a mess and filesystems such as Ext4
define flags that aren't in linux/fs.h, so translation in the kernel
may be a necessity (or, possibly, we provide the filesystem type too).
(Some attributes are made available in stx_attributes, but the general
feeling was that the IOC flags were to ext[234]-specific and shouldn't
be exposed through statx this way).
(15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
Michael Kerrisk].
(Deferred, probably to fsinfo. Finding out if there's an ACL or
seclabal might require extra filesystem operations).
(16) Femtosecond-resolution timestamps [Dave Chinner].
(A __reserved field has been left in the statx_timestamp struct for
this - if there proves to be a need).
(17) A set multiple attributes syscall to go with this.
===============
NEW SYSTEM CALL
===============
The new system call is:
int ret = statx(int dfd,
const char *filename,
unsigned int flags,
unsigned int mask,
struct statx *buffer);
The dfd, filename and flags parameters indicate the file to query, in a
similar way to fstatat(). There is no equivalent of lstat() as that can be
emulated with statx() by passing AT_SYMLINK_NOFOLLOW in flags. There is
also no equivalent of fstat() as that can be emulated by passing a NULL
filename to statx() with the fd of interest in dfd.
Whether or not statx() synchronises the attributes with the backing store
can be controlled by OR'ing a value into the flags argument (this typically
only affects network filesystems):
(1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this
respect.
(2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise
its attributes with the server - which might require data writeback to
occur to get the timestamps correct.
(3) AT_STATX_DONT_SYNC will suppress synchronisation with the server in a
network filesystem. The resulting values should be considered
approximate.
mask is a bitmask indicating the fields in struct statx that are of
interest to the caller. The user should set this to STATX_BASIC_STATS to
get the basic set returned by stat(). It should be noted that asking for
more information may entail extra I/O operations.
buffer points to the destination for the data. This must be 256 bytes in
size.
======================
MAIN ATTRIBUTES RECORD
======================
The following structures are defined in which to return the main attribute
set:
struct statx_timestamp {
__s64 tv_sec;
__s32 tv_nsec;
__s32 __reserved;
};
struct statx {
__u32 stx_mask;
__u32 stx_blksize;
__u64 stx_attributes;
__u32 stx_nlink;
__u32 stx_uid;
__u32 stx_gid;
__u16 stx_mode;
__u16 __spare0[1];
__u64 stx_ino;
__u64 stx_size;
__u64 stx_blocks;
__u64 __spare1[1];
struct statx_timestamp stx_atime;
struct statx_timestamp stx_btime;
struct statx_timestamp stx_ctime;
struct statx_timestamp stx_mtime;
__u32 stx_rdev_major;
__u32 stx_rdev_minor;
__u32 stx_dev_major;
__u32 stx_dev_minor;
__u64 __spare2[14];
};
The defined bits in request_mask and stx_mask are:
STATX_TYPE Want/got stx_mode & S_IFMT
STATX_MODE Want/got stx_mode & ~S_IFMT
STATX_NLINK Want/got stx_nlink
STATX_UID Want/got stx_uid
STATX_GID Want/got stx_gid
STATX_ATIME Want/got stx_atime{,_ns}
STATX_MTIME Want/got stx_mtime{,_ns}
STATX_CTIME Want/got stx_ctime{,_ns}
STATX_INO Want/got stx_ino
STATX_SIZE Want/got stx_size
STATX_BLOCKS Want/got stx_blocks
STATX_BASIC_STATS [The stuff in the normal stat struct]
STATX_BTIME Want/got stx_btime{,_ns}
STATX_ALL [All currently available stuff]
stx_btime is the file creation time, stx_mask is a bitmask indicating the
data provided and __spares*[] are where as-yet undefined fields can be
placed.
Time fields are structures with separate seconds and nanoseconds fields
plus a reserved field in case we want to add even finer resolution. Note
that times will be negative if before 1970; in such a case, the nanosecond
fields will also be negative if not zero.
The bits defined in the stx_attributes field convey information about a
file, how it is accessed, where it is and what it does. The following
attributes map to FS_*_FL flags and are the same numerical value:
STATX_ATTR_COMPRESSED File is compressed by the fs
STATX_ATTR_IMMUTABLE File is marked immutable
STATX_ATTR_APPEND File is append-only
STATX_ATTR_NODUMP File is not to be dumped
STATX_ATTR_ENCRYPTED File requires key to decrypt in fs
Within the kernel, the supported flags are listed by:
KSTAT_ATTR_FS_IOC_FLAGS
[Are any other IOC flags of sufficient general interest to be exposed
through this interface?]
New flags include:
STATX_ATTR_AUTOMOUNT Object is an automount trigger
These are for the use of GUI tools that might want to mark files specially,
depending on what they are.
Fields in struct statx come in a number of classes:
(0) stx_dev_*, stx_blksize.
These are local system information and are always available.
(1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time, stx_ino,
stx_size, stx_blocks.
These will be returned whether the caller asks for them or not. The
corresponding bits in stx_mask will be set to indicate whether they
actually have valid values.
If the caller didn't ask for them, then they may be approximated. For
example, NFS won't waste any time updating them from the server,
unless as a byproduct of updating something requested.
If the values don't actually exist for the underlying object (such as
UID or GID on a DOS file), then the bit won't be set in the stx_mask,
even if the caller asked for the value. In such a case, the returned
value will be a fabrication.
Note that there are instances where the type might not be valid, for
instance Windows reparse points.
(2) stx_rdev_*.
This will be set only if stx_mode indicates we're looking at a
blockdev or a chardev, otherwise will be 0.
(3) stx_btime.
Similar to (1), except this will be set to 0 if it doesn't exist.
=======
TESTING
=======
The following test program can be used to test the statx system call:
samples/statx/test-statx.c
Just compile and run, passing it paths to the files you want to examine.
The file is built automatically if CONFIG_SAMPLES is enabled.
Here's some example output. Firstly, an NFS directory that crosses to
another FSID. Note that the AUTOMOUNT attribute is set because transiting
this directory will cause d_automount to be invoked by the VFS.
[root@andromeda ~]# /tmp/test-statx -A /warthog/data
statx(/warthog/data) = 0
results=7ff
Size: 4096 Blocks: 8 IO Block: 1048576 directory
Device: 00:26 Inode: 1703937 Links: 125
Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041
Access: 2016-11-24 09:02:12.219699527+0000
Modify: 2016-11-17 10:44:36.225653653+0000
Change: 2016-11-17 10:44:36.225653653+0000
Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------)
Secondly, the result of automounting on that directory.
[root@andromeda ~]# /tmp/test-statx /warthog/data
statx(/warthog/data) = 0
results=7ff
Size: 4096 Blocks: 8 IO Block: 1048576 directory
Device: 00:27 Inode: 2 Links: 125
Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041
Access: 2016-11-24 09:02:12.219699527+0000
Modify: 2016-11-17 10:44:36.225653653+0000
Change: 2016-11-17 10:44:36.225653653+0000
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If overlay was mounted by root then quota set for upper layer does not work
because overlay now always use mounter's credentials for operations.
Also overlay might deplete reserved space and inodes in ext4.
This patch drops capability SYS_RESOURCE from saved credentials.
This affects creation new files, whiteouts, and copy-up operations.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 1175b6b8d9 ("ovl: do operations on underlying file system in mounter's context")
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
overlayfs syncs all inode pages on sync_filesystem(), but it also
needs to call s_op->sync_fs() of upper fs for metadata sync.
This fixes correctness of syncfs(2) as demonstrated by following
xfs specific test:
xfs_sync_stats()
{
echo $1
echo -n "xfs_log_force = "
grep log /proc/fs/xfs/stat | awk '{ print $5 }'
}
xfs_sync_stats "before touch"
touch x
xfs_sync_stats "after touch"
xfs_io -c syncfs .
xfs_sync_stats "after syncfs"
xfs_io -c fsync x
xfs_sync_stats "after fsync"
xfs_io -c fsync x
xfs_sync_stats "after fsync #2"
When this test is run in overlay mount over xfs, log force
count does not increase with syncfs command.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Now that copy up of regular file is done using O_TMPFILE,
we don't need to hold rename_lock throughout copy up.
Use the copy up waitqueue to synchronize concurrent copy up
of the same file. Different regular files can be copied up
concurrently.
The upper dir inode_lock is taken instead of rename_lock,
because it is needed for lookup and later for linking the
temp file, but it is released while copying up data.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The overlay sb 'copyup_wq' and overlay inode 'copying' condition
variable are about to replace the upper sb rename_lock, as finer
grained synchronization objects for concurrent copy up.
Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
In preparation for concurrent copy up, implement copy up
of regular file as O_TMPFILE that is linked to upperdir
instead of a file in workdir that is moved to upperdir.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
As preparation to implementing copy up with O_TMPFILE,
name the variable for dentry before final rename 'temp' and
assign it to 'newdentry' only after rename.
Also lookup upper dentry before looking up temp dentry and
move ovl_set_timestamps() into ovl_copy_up_locked(), because
that is going to be more convenient for upcoming change.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This is needed for choosing between concurrent copyup
using O_TMPFILE and legacy copyup using workdir+rename.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ovl_lookup_layer() iterates on path elements of d->name.name
but also frees and allocates a new pointer for d->name.name.
For the case of lookup in upper layer, the initial d->name.name
pointer is stable (dentry->d_name), but for lower layers, the
initial d->name.name can be d->redirect, which can be freed during
iteration.
[SzM]
Keep the count of remaining characters in the redirect path and calculate
the current position from that. This works becuase only the prefix is
modified, the ending always stays the same.
Fixes: 02b69b284c ("ovl: lookup redirects")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pull partial readlink cleanups from Miklos Szeredi.
This is the uncontroversial part of the readlink cleanup patch-set that
simplifies the default readlink handling.
Miklos and Al are still discussing the rest of the series.
* git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
vfs: make generic_readlink() static
vfs: remove ".readlink = generic_readlink" assignments
vfs: default to generic_readlink()
vfs: replace calling i_op->readlink with vfs_readlink()
proc/self: use generic_readlink
ecryptfs: use vfs_get_link()
bad_inode: add missing i_op initializers
Pull overlayfs updates from Miklos Szeredi:
"This update contains:
- try to clone on copy-up
- allow renaming a directory
- split source into managable chunks
- misc cleanups and fixes
It does not contain the read-only fd data inconsistency fix, which Al
didn't like. I'll leave that to the next year..."
* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (36 commits)
ovl: fix reStructuredText syntax errors in documentation
ovl: fix return value of ovl_fill_super
ovl: clean up kstat usage
ovl: fold ovl_copy_up_truncate() into ovl_copy_up()
ovl: create directories inside merged parent opaque
ovl: opaque cleanup
ovl: show redirect_dir mount option
ovl: allow setting max size of redirect
ovl: allow redirect_dir to default to "on"
ovl: check for emptiness of redirect dir
ovl: redirect on rename-dir
ovl: lookup redirects
ovl: consolidate lookup for underlying layers
ovl: fix nested overlayfs mount
ovl: check namelen
ovl: split super.c
ovl: use d_is_dir()
ovl: simplify lookup
ovl: check lower existence of rename target
ovl: rename: simplify handling of lower/merged directory
...
Pull vfs updates from Al Viro:
- more ->d_init() stuff (work.dcache)
- pathname resolution cleanups (work.namei)
- a few missing iov_iter primitives - copy_from_iter_full() and
friends. Either copy the full requested amount, advance the iterator
and return true, or fail, return false and do _not_ advance the
iterator. Quite a few open-coded callers converted (and became more
readable and harder to fuck up that way) (work.iov_iter)
- several assorted patches, the big one being logfs removal
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
logfs: remove from tree
vfs: fix put_compat_statfs64() does not handle errors
namei: fold should_follow_link() with the step into not-followed link
namei: pass both WALK_GET and WALK_MORE to should_follow_link()
namei: invert WALK_PUT logics
namei: shift interpretation of LOOKUP_FOLLOW inside should_follow_link()
namei: saner calling conventions for mountpoint_last()
namei.c: get rid of user_path_parent()
switch getfrag callbacks to ..._full() primitives
make skb_add_data,{_nocache}() and skb_copy_to_page_nocache() advance only on success
[iov_iter] new primitives - copy_from_iter_full() and friends
don't open-code file_inode()
ceph: switch to use of ->d_init()
ceph: unify dentry_operations instances
lustre: switch to use of ->d_init()
If kcalloc() failed, the return value of ovl_fill_super() is -EINVAL,
not -ENOMEM. So this patch sets this value to -ENOMEM before calling
kcalloc(), and sets it back to -EINVAL after calling kcalloc().
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
FWIW, there's a bit of abuse of struct kstat in overlayfs object
creation paths - for one thing, it ends up with a very small subset
of struct kstat (mode + rdev), for another it also needs link in
case of symlinks and ends up passing it separately.
IMO it would be better to introduce a separate object for that.
In principle, we might even lift that thing into general API and switch
->mkdir()/->mknod()/->symlink() to identical calling conventions. Hell
knows, perhaps ->create() as well...
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The benefit of making directories opaque on creation is that lookups can
stop short when they reach the original created directory, instead of
continue lookup the entire depth of parent directory stack.
The best case is overlay with N layers, performing lookup for first level
directory, which exists only in upper. In that case, there will be only
one lookup instead of N.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
oe->opaque is set for
a) whiteouts
b) directories having the "trusted.overlay.opaque" xattr
Case b can be simplified, since setting the xattr always implies setting
oe->opaque. Also once set, the opaque flag is never cleared.
Don't need to set opaque flag for non-directories.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Add a module option to allow tuning the max size of absolute redirects.
Default is 256.
Size of relative redirects is naturally limited by the the underlying
filesystem's max filename length (usually 255).
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This patch introduces a kernel config option and a module param. Both can
be used independently to turn the default value of redirect_dir on or off.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Before introducing redirect_dir feature, the condition
!ovl_lower_positive(dentry) for a directory, implied that it is a pure
upper directory, which may be removed if empty.
Now that directory can be redirect, it is possible that upper does not
cover any lower (i.e. !ovl_lower_positive(dentry)), but the directory is a
merge (with redirected path) and maybe non empty.
Check for this case in ovl_remove_upper().
This change fixes the following test case from rename-pop-dir.py
of unionmount-testsuite:
"""Remove dir and rename old name"""
d = ctx.non_empty_dir()
d2 = ctx.no_dir()
ctx.rmdir(d, err=ENOTEMPTY)
ctx.rename(d, d2)
ctx.rmdir(d, err=ENOENT)
ctx.rmdir(d2, err=ENOTEMPTY)
./run --ov rename-pop-dir
/mnt/a/no_dir103: Expected error (Directory not empty) was not produced
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Current code returns EXDEV when a directory would need to be copied up to
move. We could copy up the directory tree in this case, but there's
another, simpler solution: point to old lower directory from moved upper
directory.
This is achieved with a "trusted.overlay.redirect" xattr storing the path
relative to the root of the overlay. After such attribute has been set,
the directory can be moved without further actions required.
This is a backward incompatible feature, old kernels won't be able to
correctly mount an overlay containing redirected directories.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If a directory has the "trusted.overlay.redirect" xattr, it means that the
value of the xattr should be used to find the underlying directory on the
next lower layer.
The redirect may be relative or absolute. Absolute redirects begin with a
slash.
A relative redirect means: instead of the current dentry's name use the
value of the redirect to find the directory in the next lower
layer. Relative redirects must not contain a slash.
An absolute redirect means: look up the directory relative to the root of
the overlay using the value of the redirect in the next lower layer.
Redirects work on lower layers as well.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Use a common helper for lookup of upper and lower layers. This paves the
way for looking up directory redirects.
No functional change.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When the upper overlayfs checks "trusted.overlay.*" xattr on the underlying
overlayfs mount, it gets -EPERM, which confuses the upper overlayfs.
Fix this by returning -EOPNOTSUPP instead of -EPERM from
ovl_own_xattr_get() and ovl_own_xattr_set(). This behavior is consistent
with the behavior of ovl_listxattr(), which filters out the private
overlayfs xattrs.
Note: nested overlays are deprecated. But this change makes sense
regardless: these xattrs are private to the overlay and should always be
hidden. Hence getting and setting them should indicate this.
[SzMi: Use EOPNOTSUPP instead of ENODATA and use it for both getting and
setting "trusted.overlay." xattrs. This is a perfectly valid error code
for "we don't support this prefix", which is the case here.]
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
We already calculate f_namelen in statfs as the maximum of the name lengths
provided by the filesystems taking part in the overlay.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
fs/overlayfs/super.c is the biggest of the overlayfs source files and it
contains various utility functions as well as the rather complicated lookup
code. Split these parts out to separate files.
Before:
1446 fs/overlayfs/super.c
After:
919 fs/overlayfs/super.c
267 fs/overlayfs/namei.c
235 fs/overlayfs/util.c
51 fs/overlayfs/ovl_entry.h
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If encountering a non-directory, then stop looking at lower layers.
In this case the oe->opaque flag is not set anymore, which doesn't matter
since existence of lower file is now checked at remove/rename time.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Check if something exists on the lower layer(s) under the target or rename
to decide if directory needs to be marked "opaque".
Marking opaque is done before the rename, and on failure the marking was
undone. Also the opaque xattr was removed if the target didn't cover
anything.
This patch changes behavior so that removal of "opaque" is not done in
either of the above cases. This means that directory may have the opaque
flag even if it doesn't cover anything. However this shouldn't affect the
performance or semantics of the overalay, while simplifying the code.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
d_is_dir() is safe to call on a negative dentry. Use this fact to simplify
handling of the lower or merged directories.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Currently ovl_lookup() checks existence of lower file even if there's a
non-directory on upper (which is always opaque). This is done so that
remove can decide whether a whiteout is needed or not.
It would be better to defer this check to unlink, since most of the time
the gathered information about opaqueness will be unused.
This adds a helper ovl_lower_positive() that checks if there's anything on
the lower layer(s).
The following patches also introduce changes to how the "opaque" attribute
is updated on directories: this attribute is added when the directory is
creted or moved over a whiteout or object covering something on the lower
layer. However following changes will allow the attribute to remain on the
directory after being moved, even if the new location doesn't cover
anything. Because of this, we need to check lower layers even for opaque
directories, so that whiteout is only created when necessary.
This function will later be also used to decide about marking a directory
opaque, so deal with negative dentries as well. When dealing with
negative, it's enough to check for being a whiteout
If the dentry is positive but not upper then it also obviously needs
whiteout/opaque.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Since commit 07a2daab49 ("ovl: Copy up underlying inode's ->i_mode to
overlay inode") sticky checking on overlay inode is performed by the vfs,
so checking against sticky on underlying inode is not needed.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This is redundant, the vfs already performed this check (and was broken,
see commit 9409e22acd ("vfs: rename: check backing inode being equal")).
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
No sense in opening special files on the underlying layers, they work just
as well if opened on the overlay.
Side effect is that it's no longer possible to connect one side of a pipe
opened on overlayfs with the other side opened on the underlying layer.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When copying up within the same fs, try to use vfs_clone_file_range().
This is very efficient when lower and upper are on the same fs
with file reflink support. If vfs_clone_file_range() fails for any
reason, copy up falls back to the regular data copy code.
Tested correct behavior when lower and upper are on:
1. same ext4 (copy)
2. same xfs + reflink patches + mkfs.xfs (copy)
3. same xfs + reflink patches + mkfs.xfs -m reflink=1 (reflink)
4. different xfs + reflink patches + mkfs.xfs -m reflink=1 (copy)
For comparison, on my laptop, xfstest overlay/001 (copy up of large
sparse files) takes less than 1 second in the xfs reflink setup vs.
25 seconds on the rest of the setups.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This reverts commit 03bea60409.
Commit 4d0c5ba2ff ("vfs: do get_write_access() on upper layer of
overlayfs") makes the writecount checks inside overlayfs superfluous, the
file is already copied up and write access acquired on the upper inode when
ovl_setattr is called with ATTR_SIZE.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If .readlink == NULL implies generic_readlink().
Generated by:
to_del="\.readlink.*=.*generic_readlink"
for i in `git grep -l $to_del`; do sed -i "/$to_del"/d $i; done
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Handling of recursion in d_real() is completely broken. Recursion is only
done in the 'inode != NULL' case. But when opening the file we have
'inode == NULL' hence d_real() will return an overlay dentry. This won't
work since overlayfs doesn't define its own file operations, so all file
ops will fail.
Fix by doing the recursion first and the check against the inode second.
Bash script to reproduce the issue written by Quentin:
- 8< - - - - - 8< - - - - - 8< - - - - - 8< - - - -
tmpdir=$(mktemp -d)
pushd ${tmpdir}
mkdir -p {upper,lower,work}
echo -n 'rocks' > lower/ksplice
mount -t overlay level_zero upper -o lowerdir=lower,upperdir=upper,workdir=work
cat upper/ksplice
tmpdir2=$(mktemp -d)
pushd ${tmpdir2}
mkdir -p {upper,work}
mount -t overlay level_one upper -o lowerdir=${tmpdir}/upper,upperdir=upper,workdir=work
ls -l upper/ksplice
cat upper/ksplice
- 8< - - - - - 8< - - - - - 8< - - - - - 8< - - - -
Reported-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 2d902671ce ("vfs: merge .d_select_inode() into .d_real()")
Cc: <stable@vger.kernel.org> # v4.8+
Make sure the copied up file hits the disk before renaming to the final
destination. If this is not done then the copy-up may corrupt the data in
the file in case of a crash.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
tmpfs doesn't have ->get_acl() because it only uses cached acls.
This fixes the acl tests in pjdfstest when tmpfs is used as the upper layer
of the overlay.
Reported-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 39a25b2b37 ("ovl: define ->get_acl() for overlay inodes")
Cc: <stable@vger.kernel.org> # v4.8
This change fixes xfstest generic/375, which failed to clear the
setgid bit in the following test case on overlayfs:
touch $testfile
chown 100:100 $testfile
chmod 2755 $testfile
_runas -u 100 -g 101 -- setfacl -m u::rwx,g::rwx,o::rwx $testfile
Reported-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Amir Goldstein <amir73il@gmail.com>
Fixes: d837a49bd5 ("ovl: fix POSIX ACL setting")
Cc: <stable@vger.kernel.org> # v4.8
Pull more misc uaccess and vfs updates from Al Viro:
"The rest of the stuff from -next (more uaccess work) + assorted fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
score: traps: Add missing include file to fix build error
fs/super.c: don't fool lockdep in freeze_super() and thaw_super() paths
fs/super.c: fix race between freeze_super() and thaw_super()
overlayfs: Fix setting IOP_XATTR flag
iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector()
blackfin: no access_ok() for __copy_{to,from}_user()
arm64: don't zero in __copy_from_user{,_inatomic}
arm: don't zero in __copy_from_user_inatomic()/__copy_from_user()
arc: don't leak bits of kernel stack into coredump
alpha: get rid of tail-zeroing in __copy_user()
Pull overlayfs updates from Miklos Szeredi:
"This update contains fixes to the "use mounter's permission to access
underlying layers" area, and miscellaneous other fixes and cleanups.
No new features this time"
* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: use vfs_get_link()
vfs: add vfs_get_link() helper
ovl: use generic_readlink
ovl: explain error values when removing acl from workdir
ovl: Fix info leak in ovl_lookup_temp()
ovl: during copy up, switch to mounter's creds early
ovl: lookup: do getxattr with mounter's permission
ovl: copy_up_xattr(): use strnlen
ovl_fill_super calls ovl_new_inode to create a root inode for the new
superblock before initializing sb->s_xattr. This wrongly causes
IOP_XATTR to be cleared in i_opflags of the new inode, causing SELinux
to log the following message:
SELinux: (dev overlay, type overlay) has no xattr support
Fix this by initializing sb->s_xattr and similar fields before calling
ovl_new_inode.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Resulting in a complete removal of a function basically implementing the
inverse of vfs_readlink().
As a bonus, now the proper security hook is also called.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
All filesystems that are backers for overlayfs would also use
generic_readlink(). Move this logic to the overlay itself, which is a nice
cleanup.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pull more vfs updates from Al Viro:
">rename2() work from Miklos + current_time() from Deepa"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Replace current_fs_time() with current_time()
fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
fs: Replace CURRENT_TIME with current_time() for inode timestamps
fs: proc: Delete inode time initializations in proc_alloc_inode()
vfs: Add current_time() api
vfs: add note about i_op->rename changes to porting
fs: rename "rename2" i_op to "rename"
vfs: remove unused i_op->rename
fs: make remaining filesystems use .rename2
libfs: support RENAME_NOREPLACE in simple_rename()
fs: support RENAME_NOREPLACE for local filesystems
ncpfs: fix unused variable warning
Pull vfs xattr updates from Al Viro:
"xattr stuff from Andreas
This completes the switch to xattr_handler ->get()/->set() from
->getxattr/->setxattr/->removexattr"
* 'work.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vfs: Remove {get,set,remove}xattr inode operations
xattr: Stop calling {get,set,remove}xattr inode operations
vfs: Check for the IOP_XATTR flag in listxattr
xattr: Add __vfs_{get,set,remove}xattr helpers
libfs: Use IOP_XATTR flag for empty directory handling
vfs: Use IOP_XATTR flag for bad-inode handling
vfs: Add IOP_XATTR inode operations flag
vfs: Move xattr_resolve_name to the front of fs/xattr.c
ecryptfs: Switch to generic xattr handlers
sockfs: Get rid of getxattr iop
sockfs: getxattr: Fail with -EOPNOTSUPP for invalid attribute names
kernfs: Switch to generic xattr handlers
hfs: Switch to generic xattr handlers
jffs2: Remove jffs2_{get,set,remove}xattr macros
xattr: Remove unnecessary NULL attribute name check
Pull misc vfs updates from Al Viro:
"Assorted misc bits and pieces.
There are several single-topic branches left after this (rename2
series from Miklos, current_time series from Deepa Dinamani, xattr
series from Andreas, uaccess stuff from from me) and I'd prefer to
send those separately"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (39 commits)
proc: switch auxv to use of __mem_open()
hpfs: support FIEMAP
cifs: get rid of unused arguments of CIFSSMBWrite()
posix_acl: uapi header split
posix_acl: xattr representation cleanups
fs/aio.c: eliminate redundant loads in put_aio_ring_file
fs/internal.h: add const to ns_dentry_operations declaration
compat: remove compat_printk()
fs/buffer.c: make __getblk_slow() static
proc: unsigned file descriptors
fs/file: more unsigned file descriptors
fs: compat: remove redundant check of nr_segs
cachefiles: Fix attempt to read i_blocks after deleting file [ver #2]
cifs: don't use memcpy() to copy struct iov_iter
get rid of separate multipage fault-in primitives
fs: Avoid premature clearing of capabilities
fs: Give dentry to inode_change_ok() instead of inode
fuse: Propagate dentry down to inode_change_ok()
ceph: Propagate dentry down to inode_change_ok()
xfs: Propagate dentry down to inode_change_ok()
...
These inode operations are no longer used; remove them.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Right now, various places in the kernel check for the existence of
getxattr, setxattr, and removexattr inode operations and directly call
those operations. Switch to helper functions and test for the IOP_XATTR
flag instead.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull security subsystem updates from James Morris:
SELinux/LSM:
- overlayfs support, necessary for container filesystems
LSM:
- finally remove the kernel_module_from_file hook
Smack:
- treat signal delivery as an 'append' operation
TPM:
- lots of bugfixes & updates
Audit:
- new audit data type: LSM_AUDIT_DATA_FILE
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (47 commits)
Revert "tpm/tpm_crb: implement tpm crb idle state"
Revert "tmp/tpm_crb: fix Intel PTT hw bug during idle state"
Revert "tpm/tpm_crb: open code the crb_init into acpi_add"
Revert "tmp/tpm_crb: implement runtime pm for tpm_crb"
lsm,audit,selinux: Introduce a new audit data type LSM_AUDIT_DATA_FILE
tmp/tpm_crb: implement runtime pm for tpm_crb
tpm/tpm_crb: open code the crb_init into acpi_add
tmp/tpm_crb: fix Intel PTT hw bug during idle state
tpm/tpm_crb: implement tpm crb idle state
tpm: add check for minimum buffer size in tpm_transmit()
tpm: constify TPM 1.x header structures
tpm/tpm_crb: fix the over 80 characters checkpatch warring
tpm/tpm_crb: drop useless cpu_to_le32 when writing to registers
tpm/tpm_crb: cache cmd_size register value.
tmp/tpm_crb: drop include to platform_device
tpm/tpm_tis: remove unused itpm variable
tpm_crb: fix incorrect values of cmdReady and goIdle bits
tpm_crb: refine the naming of constants
tpm_crb: remove wmb()'s
tpm_crb: fix crb_req_canceled behavior
...
inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
The function uses the memory address of a struct dentry as unique id.
While the address-based directory entry is only visible to root it is IMHO
still worth fixing since the temporary name does not have to be a kernel
address. It can be any unique number. Replace it by an atomic integer
which is allowed to wrap around.
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v3.18+
Fixes: e9be9d5e76 ("overlay filesystem")
Now, we have the notion that copy up of a file is done with the creds
of mounter of overlay filesystem (as opposed to task). Right now before
we switch creds, we do some vfs_getattr() operations in the context of
task and that itself can fail. We should do that getattr() using the
creds of mounter instead.
So this patch switches to mounter's creds early during copy up process so
that even vfs_getattr() is done with mounter's creds.
Do not call revert_creds() unless we have already called
ovl_override_creds(). [Reported by Arnd Bergmann]
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The getxattr() in ovl_is_opaquedir() was missed when converting all
operations on underlying fs to be done under mounter's permission.
This patch fixes this by moving the ovl_override_creds()/revert_creds() out
from ovl_lookup_real() to ovl_lookup().
Also convert to using vfs_getxattr() instead of directly calling
i_op->getxattr().
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Be defensive about what underlying fs provides us in the returned xattr
list buffer. strlen() may overrun the buffer, so use strnlen() and WARN if
the contents are not properly null terminated.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
This patch allows flock, posix locks, ofd locks and leases to work
correctly on overlayfs.
Instead of using the underlying inode for storing lock context use the
overlay inode. This allows locks to be persistent across copy-up.
This is done by introducing locks_inode() helper and using it instead of
file_inode() to get the inode in locking code. For non-overlayfs the two
are equivalent, except for an extra pointer dereference in locks_inode().
Since lock operations are in "struct file_operations" we must also make
sure not to call underlying filesystem's lock operations. Introcude a
super block flag MS_NOREMOTELOCK to this effect.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Jeff Layton <jlayton@poochiereds.net>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Workdir creation fails in latest kernel.
Fix by allowing EOPNOTSUPP as a valid return value from
vfs_removexattr(XATTR_NAME_POSIX_ACL_*). Upper filesystem may not support
ACL and still be perfectly able to support overlayfs.
Reported-by: Martin Ziegler <ziegler@uni-freiburg.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: c11b9fdd6a ("ovl: remove posix_acl_default from workdir")
Cc: <stable@vger.kernel.org>
Be defensive about what underlying fs provides us in the returned xattr
list buffer. If it's not properly null terminated, bail out with a warning
insead of BUG.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Now that overlayfs has xattr handlers for iop->{set,remove}xattr, use
those same handlers for iop->getxattr as well.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Setting POSIX acl may also modify the file mode, so need to copy that up to
the overlay inode.
Reported-by: Eryu Guan <eguan@redhat.com>
Fixes: d837a49bd5 ("ovl: fix POSIX ACL setting")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Commit d837a49bd5 ("ovl: fix POSIX ACL setting") switches from
iop->setxattr from ovl_setxattr to generic_setxattr, so switch from
ovl_removexattr to generic_removexattr as well. As far as permission
checking goes, the same rules should apply in either case.
While doing that, rename ovl_setxattr to ovl_xattr_set to indicate that
this is not an iop->setxattr implementation and remove the unused inode
argument.
Move ovl_other_xattr_set above ovl_own_xattr_set so that they match the
order of handlers in ovl_xattr_handlers.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Fixes: d837a49bd5 ("ovl: fix POSIX ACL setting")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Use an ordinary #ifdef to conditionally include the POSIX ACL handlers
in ovl_xattr_handlers, like the other filesystems do. Flag the code
that is now only used conditionally with __maybe_unused.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Trivial fix to spelling mistake in pr_err message.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Some operations (setxattr/chmod) can make the cached acl stale. We either
need to clear overlay's acl cache for the affected inode or prevent acl
caching on the overlay altogether. Preventing caching has the following
advantages:
- no double caching, less memory used
- overlay cache doesn't go stale when fs clears it's own cache
Possible disadvantage is performance loss. If that becomes a problem
get_acl() can be optimized for overlayfs.
This patch disables caching by pre setting i_*acl to a value that
- has bit 0 set, so is_uncached_acl() will return true
- is not equal to ACL_NOT_CACHED, so get_acl() will not overwrite it
The constant -3 was chosen for this purpose.
Fixes: 39a25b2b37 ("ovl: define ->get_acl() for overlay inodes")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Instead of calling ->get_acl() directly, use get_acl() to get the cached
value.
We will have the acl cached on the underlying inode anyway, because we do
permission checking on the both the overlay and the underlying fs.
So, since we already have double caching, this improves performance without
any cost.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When mounting overlayfs it needs a clean "work" directory under the
supplied workdir.
Previously the mount code removed this directory if it already existed and
created a new one. If the removal failed (e.g. directory was not empty)
then it fell back to a read-only mount not using the workdir.
While this has never been reported, it is possible to get a non-empty
"work" dir from a previous mount of overlayfs in case of crash in the
middle of an operation using the work directory.
In this case the left over state should be discarded and the overlay
filesystem will be consistent, guaranteed by the atomicity of operations on
moving to/from the workdir to the upper layer.
This patch implements cleaning out any files left in workdir. It is
implemented using real recursion for simplicity, but the depth is limited
to 2, because the worst case is that of a directory containing whiteouts
under "work".
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Clear out posix acl xattrs on workdir and also reset the mode after
creation so that an inherited sgid bit is cleared.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Setting MS_POSIXACL in sb->s_flags has the side effect of passing mode to
create functions without masking against umask.
Another problem when creating over a whiteout is that the default posix acl
is not inherited from the parent dir (because the real parent dir at the
time of creation is the work directory).
Fix these problems by:
a) If upper fs does not have MS_POSIXACL, then mask mode with umask.
b) If creating over a whiteout, call posix_acl_create() to get the
inherited acls. After creation (but before moving to the final
destination) set these acls on the created file. posix_acl_create() also
updates the file creation mode as appropriate.
Fixes: 39a25b2b37 ("ovl: define ->get_acl() for overlay inodes")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
During a new file creation we need to make sure new file is created with the
right label. New file is created in upper/ so effectively file should get
label as if task had created file in upper/.
We switched to mounter's creds for actual file creation. Also if there is a
whiteout present, then file will be created in work/ dir first and then
renamed in upper. In none of the cases file will be labeled as we want it to
be.
This patch introduces a new hook dentry_create_files_as(), which determines
the label/context dentry will get if it had been created by task in upper
and modify passed set of creds appropriately. Caller makes use of these new
creds for file creation.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: fix whitespace issues found with checkpatch.pl]
[PM: changes to use stat->mode in ovl_create_or_link()]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Provide a security hook which is called when xattrs of a file are being
copied up. This hook is called once for each xattr and LSM can return
0 if the security module wants the xattr to be copied up, 1 if the
security module wants the xattr to be discarded on the copy, -EOPNOTSUPP
if the security module does not handle/manage the xattr, or a -errno
upon an error.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: whitespace cleanup for checkpatch.pl]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Provide a security hook to label new file correctly when a file is copied
up from lower layer to upper layer of a overlay/union mount.
This hook can prepare a new set of creds which are suitable for new file
creation during copy up. Caller will use new creds to create file and then
revert back to old creds and release new creds.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: whitespace cleanup to appease checkpatch.pl]
Signed-off-by: Paul Moore <paul@paul-moore.com>
When a copy up of a directory occurs which has the opaque xattr set, the
xattr remains in the upper directory. The immediate behavior with overlayfs
is that the upper directory is not treated as opaque, however after a
remount the opaque flag is used and upper directory is treated as opaque.
This causes files created in the lower layer to be hidden when using
multiple lower directories.
Fix by not copying up the opaque flag.
To reproduce:
----8<---------8<---------8<---------8<---------8<---------8<----
mkdir -p l/d/s u v w mnt
mount -t overlay overlay -olowerdir=l,upperdir=u,workdir=w mnt
rm -rf mnt/d/
mkdir -p mnt/d/n
umount mnt
mount -t overlay overlay -olowerdir=u:l,upperdir=v,workdir=w mnt
touch mnt/d/foo
umount mnt
mount -t overlay overlay -olowerdir=u:l,upperdir=v,workdir=w mnt
ls mnt/d
----8<---------8<---------8<---------8<---------8<---------8<----
output should be: "foo n"
Reported-by: Derek McGowan <dmcg@drizz.net>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=151291
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
The empty checking logic is duplicated in ovl_check_empty_and_clear() and
ovl_remove_and_whiteout(), except the condition for clearing whiteouts is
different:
ovl_check_empty_and_clear() checked for being upper
ovl_remove_and_whiteout() checked for merge OR lower
Move the intersection of those checks (upper AND merge) into
ovl_check_empty_and_clear() and simplify ovl_remove_and_whiteout().
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This does not work and does not make sense. So instead of fixing it
(probably not hard) just disallow.
Reported-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Right now we remove MAY_WRITE/MAY_APPEND bits from mask if realfile is on
lower/. This is done as files on lower will never be written and will be
copied up. But to copy up a file, mounter should have MAY_READ permission
otherwise copy up will fail. So set MAY_READ in mask when MAY_WRITE is
reset.
Dan Walsh noticed this when he did access(lowerfile, W_OK) and it returned
True (context mounts) but when he tried to actually write to file, it
failed as mounter did not have permission on lower file.
[SzM] don't set MAY_READ if only MAY_APPEND is set without MAY_WRITE; this
won't trigger a copy-up.
Reported-by: Dan Walsh <dwalsh@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Right now if file is on lower/, we remove MAY_WRITE/MAY_APPEND bits from
mask as lower/ will never be written and file will be copied up. But this
is not true for special files. These files are not copied up and are opened
in place. So don't dilute the checks for these types of files.
Reported-by: Dan Walsh <dwalsh@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Setting POSIX ACL needs special handling:
1) Some permission checks are done by ->setxattr() which now uses mounter's
creds ("ovl: do operations on underlying file system in mounter's
context"). These permission checks need to be done with current cred as
well.
2) Setting ACL can fail for various reasons. We do not need to copy up in
these cases.
In the mean time switch to using generic_setxattr.
[Arnd Bergmann] Fix link error without POSIX ACL. posix_acl_from_xattr()
doesn't have a 'static inline' implementation when CONFIG_FS_POSIX_ACL is
disabled, and I could not come up with an obvious way to do it.
This instead avoids the link error by defining two sets of ACL operations
and letting the compiler drop one of the two at compile time depending
on CONFIG_FS_POSIX_ACL. This avoids all references to the ACL code,
also leading to smaller code.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
