linux.git/fs/overlayfs, branch v4.8

ovl: fix workdir creation

2016-09-05T11:55:20+00:00

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 
Signed-off-by: Miklos Szeredi 
Fixes: c11b9fdd6a61 ("ovl: remove posix_acl_default from workdir")
Cc:

ovl: listxattr: use strnlen()

2016-09-01T09:12:00+00:00

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 
Cc:

ovl: Switch to generic_getxattr

2016-09-01T09:12:00+00:00

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 
Signed-off-by: Miklos Szeredi

ovl: copyattr after setting POSIX ACL

2016-09-01T09:12:00+00:00

Setting POSIX acl may also modify the file mode, so need to copy that up to
the overlay inode.

Reported-by: Eryu Guan 
Fixes: d837a49bd57f ("ovl: fix POSIX ACL setting")
Signed-off-by: Miklos Szeredi

ovl: Switch to generic_removexattr

2016-09-01T09:12:00+00:00

Commit d837a49bd57f ("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 
Fixes: d837a49bd57f ("ovl: fix POSIX ACL setting")
Signed-off-by: Miklos Szeredi

ovl: Get rid of ovl_xattr_noacl_handlers array

2016-09-01T09:11:59+00:00

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 
Signed-off-by: Miklos Szeredi

ovl: Fix OVL_XATTR_PREFIX

2016-09-01T09:11:59+00:00

Make sure ovl_own_xattr_handler only matches attribute names starting
with "overlay.", not "overlayXXX".

Signed-off-by: Andreas Gruenbacher 
Fixes: d837a49bd57f ("ovl: fix POSIX ACL setting")
Signed-off-by: Miklos Szeredi

ovl: fix spelling mistake: "directries" -> "directories"

2016-09-01T09:11:59+00:00

Trivial fix to spelling mistake in pr_err message.

Signed-off-by: Colin Ian King 
Signed-off-by: Miklos Szeredi

ovl: don't cache acl on overlay layer

2016-09-01T09:11:59+00:00

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: 39a25b2b3762 ("ovl: define ->get_acl() for overlay inodes")
Signed-off-by: Miklos Szeredi

ovl: use cached acl on underlying layer

2016-09-01T09:11:59+00:00

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