2
0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-26 06:04:14 +08:00
Commit Graph

141 Commits

Author SHA1 Message Date
Linus Torvalds
0f0d12728e Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull mount flag updates from Al Viro:
 "Another chunk of fmount preparations from dhowells; only trivial
  conflicts for that part. It separates MS_... bits (very grotty
  mount(2) ABI) from the struct super_block ->s_flags (kernel-internal,
  only a small subset of MS_... stuff).

  This does *not* convert the filesystems to new constants; only the
  infrastructure is done here. The next step in that series is where the
  conflicts would be; that's the conversion of filesystems. It's purely
  mechanical and it's better done after the merge, so if you could run
  something like

	list=$(for i in MS_RDONLY MS_NOSUID MS_NODEV MS_NOEXEC MS_SYNCHRONOUS MS_MANDLOCK MS_DIRSYNC MS_NOATIME MS_NODIRATIME MS_SILENT MS_POSIXACL MS_KERNMOUNT MS_I_VERSION MS_LAZYTIME; do git grep -l $i fs drivers/staging/lustre drivers/mtd ipc mm include/linux; done|sort|uniq|grep -v '^fs/namespace.c$')

	sed -i -e 's/\<MS_RDONLY\>/SB_RDONLY/g' \
	        -e 's/\<MS_NOSUID\>/SB_NOSUID/g' \
	        -e 's/\<MS_NODEV\>/SB_NODEV/g' \
	        -e 's/\<MS_NOEXEC\>/SB_NOEXEC/g' \
	        -e 's/\<MS_SYNCHRONOUS\>/SB_SYNCHRONOUS/g' \
	        -e 's/\<MS_MANDLOCK\>/SB_MANDLOCK/g' \
	        -e 's/\<MS_DIRSYNC\>/SB_DIRSYNC/g' \
	        -e 's/\<MS_NOATIME\>/SB_NOATIME/g' \
	        -e 's/\<MS_NODIRATIME\>/SB_NODIRATIME/g' \
	        -e 's/\<MS_SILENT\>/SB_SILENT/g' \
	        -e 's/\<MS_POSIXACL\>/SB_POSIXACL/g' \
	        -e 's/\<MS_KERNMOUNT\>/SB_KERNMOUNT/g' \
	        -e 's/\<MS_I_VERSION\>/SB_I_VERSION/g' \
	        -e 's/\<MS_LAZYTIME\>/SB_LAZYTIME/g' \
	        $list

  and commit it with something along the lines of 'convert filesystems
  away from use of MS_... constants' as commit message, it would save a
  quite a bit of headache next cycle"

* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  VFS: Differentiate mount flags (MS_*) from internal superblock flags
  VFS: Convert sb->s_flags & MS_RDONLY to sb_rdonly(sb)
  vfs: Add sb_rdonly(sb) to query the MS_RDONLY flag on s_flags
2017-09-14 18:54:01 -07:00
Miklos Szeredi
cd91304e71 ovl: fix relatime for directories
Need to treat non-regular overlayfs files the same as regular files when
checking for an atime update.

Add a d_real() flag to make it return the upper dentry for all file types.

Reported-by: "zhangyi (F)" <yi.zhang@huawei.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-09-05 12:53:11 +02:00
Miklos Szeredi
495e642939 vfs: add flags to d_real()
Add a separate flags argument (in addition to the open flags) to control
the behavior of d_real().

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-09-04 21:42:22 +02:00
Miklos Szeredi
191a3980c6 ovl: cleanup d_real for negative
d_real() is never called with a negative dentry.  So remove the
d_is_negative() check (which would never trigger anyway, since d_is_reg()
returns false for a negative dentry).

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-09-04 16:44:42 +02:00
Miklos Szeredi
4edb83bb10 ovl: constant d_ino for non-merge dirs
Impure directories are ones which contain objects with origins (i.e. those
that have been copied up).  These are relevant to readdir operation only
because of the d_ino field, no other transformation is necessary.  Also a
directory can become impure between two getdents(2) calls.

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

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

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

This patch also fixes up handling of d_ino for the ".." entry if the parent
directory is merged.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-27 21:54:06 +02:00
Miklos Szeredi
1d88f18373 ovl: fix xattr get and set with selinux
inode_doinit_with_dentry() in SELinux wants to read the upper inode's xattr
to get security label, and ovl_xattr_get() calls ovl_dentry_real(), which
depends on dentry->d_inode, but d_inode is null and not initialized yet at
this point resulting in an Oops.

Fix by getting the upperdentry info from the inode directly in this case.

Reported-by: Eryu Guan <eguan@redhat.com>
Fixes: 09d8b58673 ("ovl: move __upperdentry to ovl_inode")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-20 11:08:21 +02:00
David Howells
bc98a42c1f VFS: Convert sb->s_flags & MS_RDONLY to sb_rdonly(sb)
Firstly by applying the following with coccinelle's spatch:

	@@ expression SB; @@
	-SB->s_flags & MS_RDONLY
	+sb_rdonly(SB)

to effect the conversion to sb_rdonly(sb), then by applying:

	@@ expression A, SB; @@
	(
	-(!sb_rdonly(SB)) && A
	+!sb_rdonly(SB) && A
	|
	-A != (sb_rdonly(SB))
	+A != sb_rdonly(SB)
	|
	-A == (sb_rdonly(SB))
	+A == sb_rdonly(SB)
	|
	-!(sb_rdonly(SB))
	+!sb_rdonly(SB)
	|
	-A && (sb_rdonly(SB))
	+A && sb_rdonly(SB)
	|
	-A || (sb_rdonly(SB))
	+A || sb_rdonly(SB)
	|
	-(sb_rdonly(SB)) != A
	+sb_rdonly(SB) != A
	|
	-(sb_rdonly(SB)) == A
	+sb_rdonly(SB) == A
	|
	-(sb_rdonly(SB)) && A
	+sb_rdonly(SB) && A
	|
	-(sb_rdonly(SB)) || A
	+sb_rdonly(SB) || A
	)

	@@ expression A, B, SB; @@
	(
	-(sb_rdonly(SB)) ? 1 : 0
	+sb_rdonly(SB)
	|
	-(sb_rdonly(SB)) ? A : B
	+sb_rdonly(SB) ? A : B
	)

to remove left over excess bracketage and finally by applying:

	@@ expression A, SB; @@
	(
	-(A & MS_RDONLY) != sb_rdonly(SB)
	+(bool)(A & MS_RDONLY) != sb_rdonly(SB)
	|
	-(A & MS_RDONLY) == sb_rdonly(SB)
	+(bool)(A & MS_RDONLY) == sb_rdonly(SB)
	)

to make comparisons against the result of sb_rdonly() (which is a bool)
work correctly.

Signed-off-by: David Howells <dhowells@redhat.com>
2017-07-17 08:45:34 +01:00
Amir Goldstein
a59f97ff66 ovl: remove unneeded check for IS_ERR()
ovl_workdir_create() returns a valid index dentry or NULL.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-13 22:06:46 +02:00
Amir Goldstein
8fc646b443 ovl: fix random return value on mount
On failure to prepare_creds(), mount fails with a random
return value, as err was last set to an integer cast of
a valid lower mnt pointer or set to 0 if inodes index feature
is enabled.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 3fe6e52f06 ("ovl: override creds with the ones from ...")
Cc: <stable@vger.kernel.org> # v4.7
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-13 22:06:45 +02:00
Amir Goldstein
caf70cb2ba ovl: cleanup orphan index entries
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>
2017-07-04 22:03:19 +02:00
Miklos Szeredi
55acc66182 ovl: add flag for upper in ovl_entry
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>
2017-07-04 22:03:18 +02:00
Amir Goldstein
415543d5c6 ovl: cleanup bad and stale index entries on mount
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>
2017-07-04 22:03:17 +02:00
Amir Goldstein
54fb347e83 ovl: verify index dir matches upper dir
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>
2017-07-04 22:03:17 +02:00
Amir Goldstein
8b88a2e640 ovl: verify upper root dir matches lower root dir
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>
2017-07-04 22:03:17 +02:00
Amir Goldstein
02bcd15774 ovl: introduce the inodes index dir feature
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>
2017-07-04 22:03:17 +02:00
Amir Goldstein
6b8aa129dc ovl: generalize ovl_create_workdir()
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>
2017-07-04 22:03:17 +02:00
Amir Goldstein
2cac0c00a6 ovl: get exclusive ownership on upper/work dirs
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>
2017-07-04 22:03:17 +02:00
Miklos Szeredi
04a01ac7ed ovl: move cache and version to ovl_inode
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-04 22:03:16 +02:00
Amir Goldstein
a015dafcaf ovl: use ovl_inode mutex to synchronize concurrent copy up
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>
2017-07-04 22:03:16 +02:00
Miklos Szeredi
13c72075ac ovl: move impure to ovl_inode
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-04 22:03:16 +02:00
Miklos Szeredi
cf31c46347 ovl: move redirect to ovl_inode
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-04 22:03:16 +02:00
Miklos Szeredi
09d8b58673 ovl: move __upperdentry to ovl_inode
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-04 22:03:16 +02:00
Miklos Szeredi
25b7713afe ovl: use i_private only as a key
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-04 22:03:16 +02:00
Miklos Szeredi
e6d2ebddbc ovl: simplify getting inode
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-07-04 22:03:16 +02:00
Amir Goldstein
13cf199d00 ovl: allocate an ovl_inode struct
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>
2017-07-04 22:03:15 +02:00
Amir Goldstein
f3a1568582 ovl: mark upper merge dir with type origin entries "impure"
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>
2017-05-29 11:48:00 +02:00
Amir Goldstein
82b749b2c6 ovl: check on mount time if upper fs supports setting xattr
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>
2017-05-18 16:11:24 +02:00
Amir Goldstein
7bcd74b98d ovl: check if all layers are on the same fs
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>
2017-05-05 11:38:57 +02:00
Amir Goldstein
b0990fbbbd ovl: check IS_APPEND() on real upper inode
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>
2017-04-20 16:37:26 +02:00
Kees Cook
33006cdf9c ovl: Use designated initializers
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>
2017-04-20 16:37:26 +02:00
Linus Torvalds
e58bc92783 Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
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
2017-03-03 12:02:42 -08:00
Ingo Molnar
5b825c3af1 sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h>
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>
2017-03-02 08:42:31 +01:00
Konstantin Khlebnikov
51f8f3c4e2 ovl: drop CAP_SYS_RESOURCE from saved mounter's credentials
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>
2017-02-07 15:47:14 +01:00
Amir Goldstein
e593b2bf51 ovl: properly implement sync_filesystem()
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>
2017-02-07 15:47:14 +01:00
Amir Goldstein
39d3d60a54 ovl: introduce copy up waitqueue
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>
2017-02-07 15:47:14 +01:00
Amir Goldstein
e7f52429b4 ovl: check if upperdir fs supports O_TMPFILE
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>
2017-02-07 15:47:14 +01:00
Geliang Tang
313684c48c ovl: fix return value of ovl_fill_super
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>
2016-12-16 11:02:57 +01:00
Al Viro
32a3d848eb ovl: clean up kstat usage
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>
2016-12-16 11:02:57 +01:00
Amir Goldstein
c5bef3a72b ovl: show redirect_dir mount option
Show the value of redirect_dir in /proc/mounts.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16 11:02:57 +01:00
Miklos Szeredi
688ea0e5a0 ovl: allow redirect_dir to default to "on"
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>
2016-12-16 11:02:57 +01:00
Miklos Szeredi
a6c6065511 ovl: redirect on rename-dir
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>
2016-12-16 11:02:56 +01:00
Miklos Szeredi
02b69b284c ovl: lookup redirects
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>
2016-12-16 11:02:56 +01:00
Amir Goldstein
48fab5d7c7 ovl: fix nested overlayfs mount
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>
2016-12-16 11:02:56 +01:00
Miklos Szeredi
6b2d5fe46f ovl: check namelen
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>
2016-12-16 11:02:56 +01:00
Miklos Szeredi
bbb1e54dd5 ovl: split super.c
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>
2016-12-16 11:02:56 +01:00
Miklos Szeredi
2b8c30e9ef ovl: use d_is_dir()
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16 11:02:56 +01:00
Miklos Szeredi
8ee6059c58 ovl: simplify lookup
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>
2016-12-16 11:02:56 +01:00
Miklos Szeredi
38e813db61 ovl: get rid of PURE type
The remainging uses of __OVL_PATH_PURE can be replaced by
ovl_dentry_is_opaque().

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16 11:02:55 +01:00
Miklos Szeredi
2aff4534b6 ovl: check lower existence when removing
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>
2016-12-16 11:02:55 +01:00
Miklos Szeredi
c412ce4983 ovl: add ovl_dentry_is_whiteout()
And use it instead of ovl_dentry_is_opaque() where appropriate.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16 11:02:55 +01:00