While updating how mmap enabled kernfs files are handled by lockdep,
9b2db6e1 ("sysfs: bail early from kernfs_file_mmap() to avoid
spurious lockdep warning") inadvertently dropped error return check
from kernfs_file_mmap().  The intention was just dropping "if
(ops->mmap)" check as the control won't reach the point if the mmap
callback isn't implemented, but I mistakenly removed the error return
check together with it.

This led to Xorg crash on i810 which was reported and bisected to the
commit and then to the specific change by Tobias.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-and-bisected-by: NTobias Powalowski <tobias.powalowski@googlemail.com>
Tested-by: NTobias Powalowski <tobias.powalowski@googlemail.com>
References: http://lkml.kernel.org/g/533D01BD.1010200@googlemail.com
Cc: stable <stable@vger.kernel.org> # 3.14
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

While implementing atomic_write_len, 4d3773c4 ("kernfs: implement
kernfs_ops->atomic_write_len") moved data copy from userland inside
kernfs_get_active() and kernfs_open_file->mutex so that
kernfs_ops->atomic_write_len can be accessed before copying buffer
from userland; unfortunately, this could lead to locking order
inversion involving mmap_sem if copy_from_user() takes a page fault.

  ======================================================
  [ INFO: possible circular locking dependency detected ]
  3.14.0-rc4-next-20140228-sasha-00011-g4077c67-dirty #26 Tainted: G        W
  -------------------------------------------------------
  trinity-c236/10658 is trying to acquire lock:
   (&of->mutex#2){+.+.+.}, at: [<fs/kernfs/file.c:487>] kernfs_fop_mmap+0x54/0x120

  but task is already holding lock:
   (&mm->mmap_sem){++++++}, at: [<mm/util.c:397>] vm_mmap_pgoff+0x6e/0xe0

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

 -> #1 (&mm->mmap_sem){++++++}:
	 [<kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131>] validate_chain+0x6c5/0x7b0
	 [<kernel/locking/lockdep.c:3182>] __lock_acquire+0x4cd/0x5a0
	 [<arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602>] lock_acquire+0x182/0x1d0
	 [<mm/memory.c:4188>] might_fault+0x7e/0xb0
	 [<arch/x86/include/asm/uaccess.h:713 fs/kernfs/file.c:291>] kernfs_fop_write+0xd8/0x190
	 [<fs/read_write.c:473>] vfs_write+0xe3/0x1d0
	 [<fs/read_write.c:523 fs/read_write.c:515>] SyS_write+0x5d/0xa0
	 [<arch/x86/kernel/entry_64.S:749>] tracesys+0xdd/0xe2

 -> #0 (&of->mutex#2){+.+.+.}:
	 [<kernel/locking/lockdep.c:1840>] check_prev_add+0x13f/0x560
	 [<kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131>] validate_chain+0x6c5/0x7b0
	 [<kernel/locking/lockdep.c:3182>] __lock_acquire+0x4cd/0x5a0
	 [<arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602>] lock_acquire+0x182/0x1d0
	 [<kernel/locking/mutex.c:470 kernel/locking/mutex.c:571>] mutex_lock_nested+0x6a/0x510
	 [<fs/kernfs/file.c:487>] kernfs_fop_mmap+0x54/0x120
	 [<mm/mmap.c:1573>] mmap_region+0x310/0x5c0
	 [<mm/mmap.c:1365>] do_mmap_pgoff+0x385/0x430
	 [<mm/util.c:399>] vm_mmap_pgoff+0x8f/0xe0
	 [<mm/mmap.c:1416 mm/mmap.c:1374>] SyS_mmap_pgoff+0x1b0/0x210
	 [<arch/x86/kernel/sys_x86_64.c:72>] SyS_mmap+0x1d/0x20
	 [<arch/x86/kernel/entry_64.S:749>] tracesys+0xdd/0xe2

  other info that might help us debug this:

   Possible unsafe locking scenario:

	 CPU0                    CPU1
	 ----                    ----
    lock(&mm->mmap_sem);
				 lock(&of->mutex#2);
				 lock(&mm->mmap_sem);
    lock(&of->mutex#2);

   *** DEADLOCK ***

  1 lock held by trinity-c236/10658:
   #0:  (&mm->mmap_sem){++++++}, at: [<mm/util.c:397>] vm_mmap_pgoff+0x6e/0xe0

  stack backtrace:
  CPU: 2 PID: 10658 Comm: trinity-c236 Tainted: G        W 3.14.0-rc4-next-20140228-sasha-00011-g4077c67-dirty #26
   0000000000000000 ffff88011911fa48 ffffffff8438e945 0000000000000000
   0000000000000000 ffff88011911fa98 ffffffff811a0109 ffff88011911fab8
   ffff88011911fab8 ffff88011911fa98 ffff880119128cc0 ffff880119128cf8
  Call Trace:
   [<lib/dump_stack.c:52>] dump_stack+0x52/0x7f
   [<kernel/locking/lockdep.c:1213>] print_circular_bug+0x129/0x160
   [<kernel/locking/lockdep.c:1840>] check_prev_add+0x13f/0x560
   [<include/linux/spinlock.h:343 mm/slub.c:1933>] ? deactivate_slab+0x511/0x550
   [<kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131>] validate_chain+0x6c5/0x7b0
   [<kernel/locking/lockdep.c:3182>] __lock_acquire+0x4cd/0x5a0
   [<mm/mmap.c:1552>] ? mmap_region+0x24a/0x5c0
   [<arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602>] lock_acquire+0x182/0x1d0
   [<fs/kernfs/file.c:487>] ? kernfs_fop_mmap+0x54/0x120
   [<kernel/locking/mutex.c:470 kernel/locking/mutex.c:571>] mutex_lock_nested+0x6a/0x510
   [<fs/kernfs/file.c:487>] ? kernfs_fop_mmap+0x54/0x120
   [<kernel/sched/core.c:2477>] ? get_parent_ip+0x11/0x50
   [<fs/kernfs/file.c:487>] ? kernfs_fop_mmap+0x54/0x120
   [<fs/kernfs/file.c:487>] kernfs_fop_mmap+0x54/0x120
   [<mm/mmap.c:1573>] mmap_region+0x310/0x5c0
   [<mm/mmap.c:1365>] do_mmap_pgoff+0x385/0x430
   [<mm/util.c:397>] ? vm_mmap_pgoff+0x6e/0xe0
   [<mm/util.c:399>] vm_mmap_pgoff+0x8f/0xe0
   [<kernel/rcu/update.c:97>] ? __rcu_read_unlock+0x44/0xb0
   [<fs/file.c:641>] ? dup_fd+0x3c0/0x3c0
   [<mm/mmap.c:1416 mm/mmap.c:1374>] SyS_mmap_pgoff+0x1b0/0x210
   [<arch/x86/kernel/sys_x86_64.c:72>] SyS_mmap+0x1d/0x20
   [<arch/x86/kernel/entry_64.S:749>] tracesys+0xdd/0xe2

Fix it by caching atomic_write_len in kernfs_open_file during open so
that it can be determined without accessing kernfs_ops in
kernfs_fop_write().  This restores the structure of kernfs_fop_write()
before 4d3773c4 with updated @len determination logic.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NSasha Levin <sasha.levin@oracle.com>
References: http://lkml.kernel.org/g/53113485.2090407@oracle.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A write to a kernfs_node is buffered through a kernel buffer.  Writes
<= PAGE_SIZE are performed atomically, while larger ones are executed
in PAGE_SIZE chunks.  While this is enough for sysfs, cgroup which is
scheduled to be converted to use kernfs needs a bit more control over
it.

This patch adds kernfs_ops->atomic_write_len.  If not set (zero), the
behavior stays the same.  If set, writes upto the size are executed
atomically and larger writes are rejected with -E2BIG.

A different implementation strategy would be allowing configuring
chunking size while making the original write size available to the
write method; however, such strategy, while being more complicated,
doesn't really buy anything.  If the write implementation has to
handle chunking, the specific chunk size shouldn't matter all that
much.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

kernfs_addrm_cxt and the accompanying kernfs_addrm_start/finish() were
added because there were operations which should be performed outside
kernfs_mutex after adding and removing kernfs_nodes.  The necessary
operations were recorded in kernfs_addrm_cxt and performed by
kernfs_addrm_finish(); however, after the recent changes which
relocated deactivation and unmapping so that they're performed
directly during removal, the only operation kernfs_addrm_finish()
performs is kernfs_put(), which can be moved inside the removal path
too.

This patch moves the kernfs_put() of the base ref to __kernfs_remove()
and remove kernfs_addrm_cxt and kernfs_addrm_start/finish().

* kernfs_add_one() is updated to grab and release kernfs_mutex itself.
  sysfs_addrm_start/finish() invocations around it are removed from
  all users.

* __kernfs_remove() puts an unlinked node directly instead of chaining
  it to kernfs_addrm_cxt.  Its callers are updated to grab and release
  kernfs_mutex instead of calling kernfs_addrm_start/finish() around
  it.

v2: Rebased on top of "kernfs: associate a new kernfs_node with its
    parent on creation" which dropped @parent from kernfs_add_one().
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Once created, a kernfs_node is always destroyed by kernfs_put().
Since ba7443bc ("sysfs, kernfs: implement
kernfs_create/destroy_root()"), kernfs_put() depends on kernfs_root()
to locate the ino_ida.  kernfs_root() in turn depends on
kernfs_node->parent being set for !dir nodes.  This means that
kernfs_put() of a !dir node requires its ->parent to be initialized.

This leads to oops when a newly created !dir node is destroyed without
going through kernfs_add_one() or after failing kernfs_add_one()
before ->parent is set.  kernfs_root() invoked from kernfs_put() will
try to dereference NULL parent.

Fix it by moving parent association to kernfs_new_node() from
kernfs_add_one().  kernfs_new_node() now takes @parent instead of
@root and determines the root from the parent and also sets the new
node's parent properly.  @parent parameter is removed from
kernfs_add_one().  As there's no parent when creating the root node,
__kernfs_new_node() which takes @root as before and doesn't set the
parent is used in that case.

This ensures that a kernfs_node in any stage in its life has its
parent associated and thus can be put.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When kernfs_seq_start() fails to obtain an active reference, it
returns ERR_PTR(-ENODEV).  kernfs_seq_stop() is then invoked with the
error pointer value; however, it still proceeds to invoke
kernfs_put_active() on the node leading to unbalanced put.

If kernfs_seq_stop() is called even after active ref failure, it
should skip invocation of @ops->seq_stop() and put_active.
Unfortunately, this is a bit complicated because active ref failure
isn't the only thing which may fail with ERR_PTR(-ENODEV).
@ops->seq_start/next() may also fail with the error value and
kernfs_seq_stop() doesn't have a way to tell apart those failures.

Work it around by factoring out the active part of kernfs_seq_stop()
into kernfs_seq_stop_active() and invoking it directly if
@ops->seq_start/next() fail with ERR_PTR(-ENODEV) and updating
kernfs_seq_stop() to skip kernfs_seq_stop_active() on
ERR_PTR(-ENODEV).  This is a bit nasty but ensures that the active put
is skipped iff get_active failed in kernfs_seq_start().

tj: This was originally committed as d92d2e6b but got reverted by
    683bb276 along with other kernfs self removal patches.
    However, this one is an independent fix and shouldn't have been
    reverted together.  Reinstate the change.  Sorry about the mess.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit d92d2e6b.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit ae34372e.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit f601f9a2.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 99177a34.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

kernfs_addrm_cxt and the accompanying kernfs_addrm_start/finish() were
added because there were operations which should be performed outside
kernfs_mutex after adding and removing kernfs_nodes.  The necessary
operations were recorded in kernfs_addrm_cxt and performed by
kernfs_addrm_finish(); however, after the recent changes which
relocated deactivation and unmapping so that they're performed
directly during removal, the only operation kernfs_addrm_finish()
performs is kernfs_put(), which can be moved inside the removal path
too.

This patch moves the kernfs_put() of the base ref to __kernfs_remove()
and remove kernfs_addrm_cxt and kernfs_addrm_start/finish().

* kernfs_add_one() is updated to grab and release the parent's active
  ref and kernfs_mutex itself.  kernfs_get/put_active() and
  kernfs_addrm_start/finish() invocations around it are removed from
  all users.

* __kernfs_remove() puts an unlinked node directly instead of chaining
  it to kernfs_addrm_cxt.  Its callers are updated to grab and release
  kernfs_mutex instead of calling kernfs_addrm_start/finish() around
  it.

v2: Updated to fit the v2 restructuring of removal path.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

kernfs_unmap_bin_file() is supposed to unmap all memory mappings of
the target file before kernfs_remove() finishes; however, it currently
is being called from kernfs_addrm_finish() and has the same race
problem as the original implementation of deactivation when there are
multiple removers - only the remover which snatches the node to its
addrm_cxt->removed list is guaranteed to wait for its completion
before returning.

It can be fixed by moving kernfs_unmap_bin_file() invocation from
kernfs_addrm_finish() to __kernfs_remove().  The function may be
called multiple times but that shouldn't do any harm.

We end up dropping kernfs_mutex in the removal loop and the node may
be removed inbetween by someone else.  kernfs_unlink_sibling() is
updated to test whether the node has already been removed and return
accordingly.  __kernfs_remove() in turn performs post-unlinking
cleanup only if it actually unlinked the node.

KERNFS_HAS_MMAP test is moved out of the unmap function into
__kernfs_remove() so that we don't unlock kernfs_mutex unnecessarily.
While at it, drop the now meaningless "bin" qualifier from the
function name.

v2: Rewritten to fit the v2 restructuring of removal path.  HAS_MMAP
    test relocated.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

KERNFS_REMOVED is used to mark half-initialized and dying nodes so
that they don't show up in lookups and deny adding new nodes under or
renaming it; however, its role overlaps those of deactivation and
removal from rbtree.

It's necessary to deny addition of new children while removal is in
progress; however, this role considerably intersects with deactivation
- KERNFS_REMOVED prevents new children while deactivation prevents new
file operations.  There's no reason to have them separate making
things more complex than necessary.

KERNFS_REMOVED is also used to decide whether a node is still visible
to vfs layer, which is rather redundant as equivalent determination
can be made by testing whether the node is on its parent's children
rbtree or not.

This patch removes KERNFS_REMOVED.

* Instead of KERNFS_REMOVED, each node now starts its life
  deactivated.  This means that we now use both atomic_add() and
  atomic_sub() on KN_DEACTIVATED_BIAS, which is INT_MIN.  The compiler
  generates an overflow warnings when negating INT_MIN as the negation
  can't be represented as a positive number.  Nothing is actually
  broken but let's bump BIAS by one to avoid the warnings for archs
  which negates the subtrahend..

* KERNFS_REMOVED tests in add and rename paths are replaced with
  kernfs_get/put_active() of the target nodes.  Due to the way the add
  path is structured now, active ref handling is done in the callers
  of kernfs_add_one().  This will be consolidated up later.

* kernfs_remove_one() is updated to deactivate instead of setting
  KERNFS_REMOVED.  This removes deactivation from kernfs_deactivate(),
  which is now renamed to kernfs_drain().

* kernfs_dop_revalidate() now tests RB_EMPTY_NODE(&kn->rb) instead of
  KERNFS_REMOVED and KERNFS_REMOVED test in kernfs_dir_pos() is
  dropped.  A node which is removed from the children rbtree is not
  included in the iteration in the first place.  This means that a
  node may be visible through vfs a bit longer - it's now also visible
  after deactivation until the actual removal.  This slightly enlarged
  window difference doesn't make any difference to the userland.

* Sanity check on KERNFS_REMOVED in kernfs_put() is replaced with
  checks on the active ref.

* Some comment style updates in the affected area.

v2: Reordered before removal path restructuring.  kernfs_active()
    dropped and kernfs_get/put_active() used instead.  RB_EMPTY_NODE()
    used in the lookup paths.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When kernfs_seq_start() fails to obtain an active reference, it
returns ERR_PTR(-ENODEV).  kernfs_seq_stop() is then invoked with the
error pointer value; however, it still proceeds to invoke
kernfs_put_active() on the node leading to unbalanced put.

If kernfs_seq_stop() is called even after active ref failure, it
should skip invocation of @ops->seq_stop() and put_active.
Unfortunately, this is a bit complicated because active ref failure
isn't the only thing which may fail with ERR_PTR(-ENODEV).
@ops->seq_start/next() may also fail with the error value and
kernfs_seq_stop() doesn't have a way to tell apart those failures.

Work it around by factoring out the active part of kernfs_seq_stop()
into kernfs_seq_stop_active() and invoking it directly if
@ops->seq_start/next() fail with ERR_PTR(-ENODEV) and updating
kernfs_seq_stop() to skip kernfs_seq_stop_active() on
ERR_PTR(-ENODEV).  This is a bit nasty but ensures that the active put
is skipped iff get_active failed in kernfs_seq_start().
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Because sysfs used struct attribute which are supposed to stay
constant, sysfs didn't copy names when creating regular files.  The
specified string for name was supposed to stay constant.  Such
distinction isn't inherent for kernfs.  kernfs_create_file[_ns]()
should be able to take the same @name as kernfs_create_dir[_ns]()

As there can be huge number of sysfs attributes, we still want to be
able to use static names for sysfs attributes.  This patch renames
kernfs_create_file_ns_key() to __kernfs_create_file() and adds
@name_is_static parameter so that the caller can explicitly indicate
that @name can be used without copying.  kernfs is updated to use
KERNFS_STATIC_NAME to distinguish static and copied names.

This patch doesn't introduce any behavior changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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_*()/kernfs_*()/ in all internal functions
* s/sysfs/kernfs/ in internal strings, comments and whatever is remaining
* Uniformly rename various vfs operations so that they're consistently
  named and distinguishable.

This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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_mutex/kernfs_mutex/
* s/sysfs_dentry_ops/kernfs_dops/
* s/sysfs_dir_operations/kernfs_dir_fops/
* s/sysfs_dir_inode_operations/kernfs_dir_iops/
* s/kernfs_file_operations/kernfs_file_fops/ - renamed for consistency
* s/sysfs_symlink_inode_operations/kernfs_symlink_iops/
* s/sysfs_aops/kernfs_aops/
* s/sysfs_backing_dev_info/kernfs_bdi/
* s/sysfs_inode_operations/kernfs_iops/
* s/sysfs_dir_cachep/kernfs_node_cache/
* s/sysfs_ops/kernfs_sops/

This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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_DIR/KERNFS_DIR/
* s/SYSFS_KOBJ_ATTR/KERNFS_FILE/
* s/SYSFS_KOBJ_LINK/KERNFS_LINK/
* s/SYSFS_{TYPE_FLAGS}/KERNFS_{TYPE_FLAGS}/
* s/SYSFS_FLAG_{FLAG}/KERNFS_{FLAG}/
* s/sysfs_type()/kernfs_type()/
* s/SD_DEACTIVATED_BIAS/KN_DEACTIVATED_BIAS/

This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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_open_dirent/kernfs_open_node/
* s/sysfs_open_file/kernfs_open_file/
* s/sysfs_inode_attrs/kernfs_iattrs/
* s/sysfs_addrm_cxt/kernfs_addrm_cxt/
* s/sysfs_super_info/kernfs_super_info/
* s/sysfs_info()/kernfs_info()/
* s/sysfs_open_dirent_lock/kernfs_open_node_lock/
* s/sysfs_open_file_mutex/kernfs_open_file_mutex/
* s/sysfs_of()/kernfs_of()/

This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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.

s_ prefix for kernfs members is used inconsistently and a misnomer
now.  It's not like kernfs_node is used widely across the kernel
making the ability to grep for the members particularly useful.  Let's
just drop the prefix.

This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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: NTejun Heo <tj@kernel.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This is v3.14 fix for the same issue that a8b14744 ("sysfs: give
different locking key to regular and bin files") addresses for v3.13.
Due to the extensive kernfs reorganization in v3.14 branch, the same
fix couldn't be ported as-is.  The v3.13 fix was ignored while merging
it into v3.14 branch.

027a485d ("sysfs: use a separate locking class for open files
depending on mmap") assigned different lockdep key to
sysfs_open_file->mutex depending on whether the file implements mmap
or not in an attempt to avoid spurious lockdep warning caused by
merging of regular and bin file paths.

While this restored some of the original behavior of using different
locks (at least lockdep is concerned) for the different clases of
files.  The restoration wasn't full because now the lockdep key
assignment depends on whether the file has mmap or not instead of
whether it's a regular file or not.

This means that bin files which don't implement mmap will get assigned
the same lockdep class as regular files.  This is problematic because
file_operations for bin files still implements the mmap file operation
and checking whether the sysfs file actually implements mmap happens
in the file operation after grabbing @sysfs_open_file->mutex.  We
still end up adding locking dependency from mmap locking to
sysfs_open_file->mutex to the regular file mutex which triggers
spurious circular locking warning.

For v3.13, a8b14744 ("sysfs: give different locking key to regular
and bin files") fixed it by giving sysfs_open_file->mutex different
lockdep keys depending on whether the file is regular or bin instead
of whether mmap exists or not; however, due to the way sysfs is now
layered behind kernfs, this approach is no longer viable.  kernfs can
tell whether a sysfs node has mmap implemented or not but can't tell
whether a bin file from a regular one.

This patch updates kernfs such that kernfs_file_mmap() checks
SYSFS_FLAG_HAS_MMAP and bail before grabbing sysfs_open_file->mutex so
that it doesn't add spurious locking dependency from mmap to
sysfs_open_file->mutex and changes sysfs so that it specifies
kernfs_ops->mmap iff the sysfs file implements mmap.  Combined, this
ensures that sysfs_open_file->mutex is grabbed under mmap path iff the
sysfs file actually implements mmap.  As sysfs_open_file->mutex is
already given a different lockdep key if mmap is implemented, this
removes the spurious locking dependency.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NDave Jones <davej@redhat.com>
Link: http://lkml.kernel.org/g/20131203184324.GA11320@redhat.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove duplicated include.
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

kernfs is being updated to allow multiple sysfs_dirent hierarchies so
that it can also be used by other users.  Currently, inode number is
allocated using a global ida, sysfs_ino_ida; however, inos for
different hierarchies should be handled separately.

This patch makes ino allocation per kernfs_root.  sysfs_ino_ida is
replaced by kernfs_root->ino_ida and sysfs_new_dirent() is updated to
take @root and allocate ino from it.  ida_simple_get/remove() are used
instead of sysfs_ino_lock and sysfs_alloc/free_ino().
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Move core file code to fs/kernfs/file.c.  fs/sysfs/file.c now contains
sysfs kernfs_ops callbacks, sysfs wrappers around kernfs interfaces,
and sysfs_schedule_callback().  The respective declarations in
fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h.

This is pure relocation.

v2: Refreshed on top of the v2 of "sysfs, kernfs: prepare read path
    for kernfs".

v3: Refreshed on top of the v3 of "sysfs, kernfs: prepare read path
    for kernfs".
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Core sysfs implementation will be separated into kernfs so that it can
be used by other non-kobject users.

This patch creates fs/kernfs/ directory and makes boilerplate changes.
kernfs interface will be directly based on sysfs_dirent and its
forward declaration is moved to include/linux/kernfs.h which is
included from include/linux/sysfs.h.  sysfs core implementation will
be gradually separated out and moved to kernfs.

This patch doesn't introduce any functional changes.

v2: mount.c added.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>