linux.git/fs/sysfs/mount.c, branch v3.14

sysfs: fix namespace refcnt leak

2014-02-25T15:37:52+00:00

As mount() and kill_sb() is not a one-to-one match, we shoudn't get
ns refcnt unconditionally in sysfs_mount(), and instead we should
get the refcnt only when kernfs_mount() allocated a new superblock.

v2:
- Changed the name of the new argument, suggested by Tejun.
- Made the argument optional, suggested by Tejun.

v3:
- Make the new argument as second-to-last arg, suggested by Tejun.

Signed-off-by: Li Zefan 
Acked-by: Tejun Heo 
 ---
 fs/kernfs/mount.c      | 8 +++++++-
 fs/sysfs/mount.c       | 5 +++--
 include/linux/kernfs.h | 9 +++++----
 3 files changed, 15 insertions(+), 7 deletions(-)
Signed-off-by: Greg Kroah-Hartman

kernfs: add kernfs_dir_ops

2013-12-17T16:59:15+00:00

Add support for mkdir(2), rmdir(2) and rename(2) syscalls.  This is
implemented through optional kernfs_dir_ops callback table which can
be specified on kernfs_create_root().  An implemented callback is
invoked when the matching syscall is invoked.

As kernfs keep dcache syncs with internal representation and
revalidates dentries on each access, the implementation of these
methods is extremely simple.  Each just discovers the relevant
kernfs_node(s) and invokes the requested callback which is allowed to
do any kernfs operations and the end result doesn't necessarily have
to match the expected semantics of the syscall.

This will be used to convert cgroup to use kernfs instead of its own
filesystem implementation.

Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

kernfs: s/sysfs_dirent/kernfs_node/ and rename its friends accordingly

2013-12-11T23:28:36+00:00

kernfs has just been separated out from sysfs and we're already in
full conflict mode.  Nothing can make the situation any worse.  Let's
take the chance to name things properly.

This patch performs the following renames.

* s/sysfs_elem_dir/kernfs_elem_dir/
* s/sysfs_elem_symlink/kernfs_elem_symlink/
* s/sysfs_elem_attr/kernfs_elem_file/
* s/sysfs_dirent/kernfs_node/
* s/sd/kn/ in kernfs proper
* s/parent_sd/parent/
* s/target_sd/target/
* s/dir_sd/parent/
* s/to_sysfs_dirent()/rb_to_kn()/
* misc renames of local vars when they conflict with the above

Because md, mic and gpio dig into sysfs details, this patch ends up
modifying them.  All are sysfs_dirent renames and trivial.  While we
can avoid these by introducing a dummy wrapping struct sysfs_dirent
around kernfs_node, given the limited usage outside kernfs and sysfs
proper, I don't think such workaround is called for.

This patch is strictly rename only and doesn't introduce any
functional difference.

- mic / gpio renames were missing.  Spotted by kbuild test robot.

Signed-off-by: Tejun Heo 
Cc: Neil Brown 
Cc: Linus Walleij 
Cc: Ashutosh Dixit 
Cc: kbuild test robot 
Signed-off-by: Greg Kroah-Hartman

sysfs: fix use-after-free in sysfs_kill_sb()

2013-12-11T06:40:12+00:00

While restructuring the [u]mount path, 4b93dc9b1c68 ("sysfs, kernfs:
prepare mount path for kernfs") incorrectly updated sysfs_kill_sb() so
that it first kills super_block and then tries to dereference its
namespace tag to drop it.  Fix it by caching namespace tag before
killing the superblock and then drop the cached namespace tag.

Signed-off-by: Tejun Heo 
Reported-by: Yuanhan Liu 
Tested-by: Yuanhan Liu 
Tested-by: Vlastimil Babka 
Link: http://lkml.kernel.org/g/20131205031051.GC5135@yliu-dev.sh.intel.com
Signed-off-by: Greg Kroah-Hartman

sysfs, kernfs: move mount core code to fs/kernfs/mount.c

2013-11-30T02:16:08+00:00

Move core mount code to fs/kernfs/mount.c.  The respective
declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs, kernfs: prepare mount path for kernfs

2013-11-30T02:16:08+00:00

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges mount path so that the kernfs and sysfs parts are separate.

* As sysfs_super_info won't be visible outside kernfs proper,
  kernfs_super_ns() is added to allow kernfs users to access a
  super_block's namespace tag.

* Generic mount operation is separated out into kernfs_mount_ns().
  sysfs_mount() now just performs sysfs-specific permission check,
  acquires namespace tag, and invokes kernfs_mount_ns().

* Generic superblock release is separated out into kernfs_kill_sb()
  which can be used directly as file_system_type->kill_sb().  As sysfs
  needs to put the namespace tag, sysfs_kill_sb() wraps
  kernfs_kill_sb() with ns tag put.

* sysfs_dir_cachep init and sysfs_inode_init() are separated out into
  kernfs_init().  kernfs_init() uses only small amount of memory and
  trying to handle and propagate kernfs_init() failure doesn't make
  much sense.  Use SLAB_PANIC for sysfs_dir_cachep and make
  sysfs_inode_init() panic on failure.

  After this change, kernfs_init() should be called before
  sysfs_init(), fs/namespace.c::mnt_init() modified accordingly.

Signed-off-by: Tejun Heo 
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig 
Signed-off-by: Greg Kroah-Hartman

sysfs, kernfs: make super_blocks bind to different kernfs_roots

2013-11-30T02:10:48+00:00

kernfs is being updated to allow multiple sysfs_dirent hierarchies so
that it can also be used by other users.  Currently, sysfs
super_blocks are always attached to one kernfs_root - sysfs_root - and
distinguished only by their namespace tags.

This patch adds sysfs_super_info->root and update
sysfs_fill/test_super() so that super_blocks are identified by the
combination of both the associated kernfs_root and namespace tag.
This allows mounting different kernfs hierarchies.

Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs, kernfs: implement kernfs_create/destroy_root()

2013-11-30T02:10:48+00:00

There currently is single kernfs hierarchy in the whole system which
is used for sysfs.  kernfs needs to support multiple hierarchies to
allow other users.  This patch introduces struct kernfs_root which
serves as the root of each kernfs hierarchy and implements
kernfs_create/destroy_root().

* Each kernfs_root is associated with a root sd (sysfs_dentry).  The
  root is freed when the root sd is released and kernfs_destory_root()
  simply invokes kernfs_remove() on the root sd.  sysfs_remove_one()
  is updated to handle release of the root sd.  Note that ps_iattr
  update in sysfs_remove_one() is trivially updated for readability.

* Root sd's are now dynamically allocated using sysfs_new_dirent().
  Update sysfs_alloc_ino() so that it gives out ino from 1 so that the
  root sd still gets ino 1.

* While kernfs currently only points to the root sd, it'll soon grow
  fields which are specific to each hierarchy.  As determining a given
  sd's root will be necessary, sd->s_dir.root is added.  This backlink
  fits better as a separate field in sd; however, sd->s_dir is inside
  union with space to spare, so use it to save space and provide
  kernfs_root() accessor to determine the root sd.

* As hierarchies may be destroyed now, each mount needs to hold onto
  the hierarchy it's attached to.  Update sysfs_fill_super() and
  sysfs_kill_sb() so that they get and put the kernfs_root
  respectively.

* sysfs_root is replaced with kernfs_root which is dynamically created
  by invoking kernfs_create_root() from sysfs_init().

This patch doesn't introduce any visible behavior changes.

v2: kernfs_create_root() forgot to set @sd->priv.  Fixed.

Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs, kernfs: introduce sysfs_root_sd

2013-11-30T02:09:27+00:00

Currently, it's assumed that there's a single kernfs hierarchy in the
system anchored at sysfs_root which is defined as a global struct.  To
allow other users of kernfs, this will be made dynamic.  Introduce a
new global variable sysfs_root_sd which points to &sysfs_root and
convert all &sysfs_root users.

This patch doesn't introduce any behavior difference.

Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs, kernfs: no need to kern_mount() sysfs from sysfs_init()

2013-11-30T02:09:27+00:00

It has been very long since sysfs depended on vfs to keep track of
internal states and whether sysfs is mounted or not doesn't make any
difference to sysfs's internal operation.

In addition to init and filesystem type registration, sysfs_init()
invokes kern_mount() to create in-kernel mount of sysfs.  This
internal mounting doesn't server any purpose anymore.  Remove it.

Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman