sysfs_add_one() is a wrapper around __sysfs_add_one() which prints out
duplicate name warning if __sysfs_add_one() fails with -EEXIST.  The
previous kernfs conversions moved all dup warnings to sysfs interface
functions and sysfs_add_one() doesn't have any user left.

Remove sysfs_add_one() and update __sysfs_add_one() to take its name.

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

Introduce kernfs interface to create a file which takes and returns
sysfs_dirents.

The actual file creation part is separated out from
sysfs_add_file_mode_ns() into kernfs_create_file_ns().  The former now
only decides the kernfs_ops to use and the file's size and invokes the
latter.

This patch doesn't introduce behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

After kernfs_ops and sysfs_dirent->s_attr.size addition, the
distinction between SYSFS_KOBJ_BIN_ATTR and SYSFS_KOBJ_ATTR is only
necessary while creating files to decide which kernfs_ops to use.
Afterwards, they behave exactly the same.

This patch removes SYSFS_KOBJ_BIN_ATTR along with sysfs_is_bin().
sysfs_add_file[_mode_ns]() are updated to take bool @is_bin instead of
@type.

This patch doesn't introduce any behavior changes.  This completely
isolates the distinction between the two sysfs file types in the sysfs
layer proper.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs sets the size of regular files unconditionally at PAGE_SIZE and
takes the size of bin files from bin_attribute.  The latter is a
pretty bad interface which forces bin_attribute users to create a
separate copy of bin_attribute for each instance of the file -
e.g. pci resource files.

Add sysfs_dirent->s_attr.size so that the size can be specified
separately.  This unifies inode init paths of ATTR and BIN_ATTR
identical and allows for generic size handling for kernfs.

Unfortunately, this grows the size of sysfs_dirent by sizeof(loff_t).
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
introduces kernfs_ops which hosts methods kernfs users implement and
updates fs/sysfs/file.c such that sysfs_kf_*() functions populate
kernfs_ops and kernfs_file_*() functions call the matching entries
from kernfs_ops.

kernfs_ops contains the following groups of methods.

* seq_show() - for kernfs files which use seq_file for reads.

* read() - for direct read implementations.  Used iff seq_show() is
  not implemented.

* write() - for writes.

* mmap() - for mmaps.

Notes:

* sysfs_elem_attr->ops is added so that kernfs_ops can be accessed
  from sysfs_dirent.  kernfs_ops() helper is added to verify locking
  and access the field.

* SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added.  sd->s_attr->ops is accessible
  only while holding active_ref and there are cases where we want to
  take different actions depending on which ops are implemented.
  These two flags cache whether the two ops are implemented for those.

* kernfs_file_*() no longer test sysfs type but chooses different
  behaviors depending on which methods in kernfs_ops are implemented.
  The conversions are trivial except for the open path.  As
  kernfs_file_open() now decides whether to allow read/write accesses
  depending on the kernfs_ops implemented, the presence of methods in
  kobjs and attribute_bin should be propagated to kernfs_ops.
  sysfs_add_file_mode_ns() is updated so that it propagates presence /
  absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs_open_file will be used as the primary handle for kernfs methods.
Move its definition from fs/sysfs/file.c to include/linux/kernfs.h and
mark the public and private fields.

This is pure relocation.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
prepares the rest - open, release and poll.  There isn't much to do.
Just renaming is enough.  As sysfs_file_operations and
sysfs_bin_operations are identical now, use the same file_operations
for both - kernfs_file_operations.

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>

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

sysfs_kf_bin_mmap() which handles the interaction with bin_attribute
mmap method is factored out of sysfs_bin_mmap(), which is renamed to
kernfs_file_mmap().  All vma ops are renamed accordingly.

sysfs_bin_mmap() is updated such that it can be used for both file
types.  This will eventually allow using the same file_operations for
both file types, which is necessary to separate out kernfs.

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>

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

kernfs_file_write() handles all boilerplate work including buffer
management and locking and invokes sysfs_kf_write() or
sysfs_kf_bin_write() depending on the file type which deals with the
interaction with kobj store or bin_attribute write method.

While this patch changes the order of some operations, it shouldn't
change any visible behavior.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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

* Regular file read path is refactored such that
  kernfs_seq_start/next/stop/show() handle all the boilerplate work
  including locking and updating event count for poll, while
  sysfs_kf_seq_show() deals with interaction with kobj show method.

* Bin file read path is refactored such that kernfs_file_direct_read()
  handles all the boilerplate work including buffer management and
  locking, while sysfs_kf_bin_read() deals with interaction with
  bin_attribute read method.

kernfs_file_read() is added.  It invokes either the seq_file or direct
read path depending on the file type.  This will eventually allow
using the same file_operations for both file types, which is necessary
to separate out kernfs.

While this patch changes the order of some operations, it shouldn't
change any visible behavior.

v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show().
    Add comments explaining single_open() behavior.  Both suggested by
    Pavel.

v3: seq_stop() is called even after seq_start() failed.
    kernfs_seq_start() updated so that it doesn't unlock
    sysfs_open_file->mutex on failure so that kernfs_seq_stop()
    doesn't try to unlock an already unlocked mutex.  Reported by
    Fengguang.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A directory sysfs_dirent points to the associated kobj.  A regular or
bin file points to the associated [bin_]attribute.  This patch
replaces sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with void *
->priv.

This is to prepare for kernfs interface so that sysfs can specify the
private data in the same way for directories and files.  This lower
debuggability but not by much - the whole thing was overlaid in a
union anyway.  If debuggability becomes an issue, we can later add
->priv accessors which explicitly check for the sysfs_dirent type and
performs casting.

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

Introduce kernfs setattr interface - kernfs_setattr().

sysfs_sd_setattr() is renamed to __kernfs_setattr() and
kernfs_setattr() is a simple wrapper around it with sysfs_mutex
locking.  sysfs_chmod_file() is updated to get an explicit ref on
kobj->sd and then invoke kernfs_setattr() so that it doesn't have to
use internal interface.

This patch doesn't introduce any behavior differences.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce kernfs removal interfaces - kernfs_remove() and
kernfs_remove_by_name[_ns]().

These are just renames of sysfs_remove() and sysfs_hash_and_remove().
No functional changes.

v2: Dummy kernfs_remove_by_name_ns() for !CONFIG_SYSFS updated to
    return -ENOSYS instead of 0.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The following two commits implemented mmap support in the regular file
path and merged bin file support into the regular path.

 73d97146 ("sysfs: copy bin mmap support from fs/sysfs/bin.c to fs/sysfs/file.c")
 3124eb16 ("sysfs: merge regular and bin file handling")

After the merge, the following commands trigger a spurious lockdep
warning.  "test-mmap-read" simply mmaps the file and dumps the
content.

  $ cat /sys/block/sda/trace/act_mask
  $ test-mmap-read /sys/devices/pci0000\:00/0000\:00\:03.0/resource0 4096

  ======================================================
  [ INFO: possible circular locking dependency detected ]
  3.12.0-work+ #378 Not tainted
  -------------------------------------------------------
  test-mmap-read/567 is trying to acquire lock:
   (&of->mutex){+.+.+.}, at: [<ffffffff8120a8df>] sysfs_bin_mmap+0x4f/0x120

  but task is already holding lock:
   (&mm->mmap_sem){++++++}, at: [<ffffffff8114b399>] vm_mmap_pgoff+0x49/0xa0

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #3 (&mm->mmap_sem){++++++}:
  ...
  -> #2 (sr_mutex){+.+.+.}:
  ...
  -> #1 (&bdev->bd_mutex){+.+.+.}:
  ...
  -> #0 (&of->mutex){+.+.+.}:
  ...

  other info that might help us debug this:

  Chain exists of:
   &of->mutex --> sr_mutex --> &mm->mmap_sem

   Possible unsafe locking scenario:

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

   *** DEADLOCK ***

  1 lock held by test-mmap-read/567:
   #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8114b399>] vm_mmap_pgoff+0x49/0xa0

  stack backtrace:
  CPU: 3 PID: 567 Comm: test-mmap-read Not tainted 3.12.0-work+ #378
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
   ffffffff81ed41a0 ffff880009441bc8 ffffffff81611ad2 ffffffff81eccb80
   ffff880009441c08 ffffffff8160f215 ffff880009441c60 ffff880009c75208
   0000000000000000 ffff880009c751e0 ffff880009c75208 ffff880009c74ac0
  Call Trace:
   [<ffffffff81611ad2>] dump_stack+0x4e/0x7a
   [<ffffffff8160f215>] print_circular_bug+0x2b0/0x2bf
   [<ffffffff8109ca0a>] __lock_acquire+0x1a3a/0x1e60
   [<ffffffff8109d6ba>] lock_acquire+0x9a/0x1d0
   [<ffffffff81615547>] mutex_lock_nested+0x67/0x3f0
   [<ffffffff8120a8df>] sysfs_bin_mmap+0x4f/0x120
   [<ffffffff8115d363>] mmap_region+0x3b3/0x5b0
   [<ffffffff8115d8ae>] do_mmap_pgoff+0x34e/0x3d0
   [<ffffffff8114b3ba>] vm_mmap_pgoff+0x6a/0xa0
   [<ffffffff8115be3e>] SyS_mmap_pgoff+0xbe/0x250
   [<ffffffff81008282>] SyS_mmap+0x22/0x30
   [<ffffffff8161a4d2>] system_call_fastpath+0x16/0x1b

This happens because one file nests sr_mutex, which nests mm->mmap_sem
under it, under of->mutex while mmap implementation naturally nests
of->mutex under mm->mmap_sem.  The warning is false positive as
of->mutex is per open-file and the two paths belong to two different
files.  This warning didn't trigger before regular and bin file
supports were merged because only bin file supported mmap and the
other side of locking happened only on regular files which used
equivalent but separate locking.

It'd be best if we give separate locking classes per file but we can't
easily do that.  Let's differentiate on ->mmap() for now.  Later we'll
add explicit file operations struct and can add per-ops lockdep key
there.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NDave Jones <davej@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

13c589d5 ("sysfs: use seq_file when reading regular files")
converted regular sysfs files to use seq_file.  The commit substituted
generic_file_llseek() with seq_lseek() for llseek implementation.

Before the change, all regular sysfs files were allowed to seek to any
position in [0, PAGE_SIZE] as the file size is always PAGE_SIZE and
generic_file_llseek() allows any seeking inside the range under file
size; however, seq_lseek()'s behavior is different.  It traverses the
output by repeatedly invoking ->show() until it reaches the target
offset or traversal indicates EOF.  As seq_files are fully dynamic and
may not end at all, it doesn't support seeking from the end
(SEEK_END).

Apparently, there are userland tools which uses SEEK_END to discover
the buffer size to use and the switch to seq_lseek() disturbs them as
SEEK_END fails with -EINVAL.

The only benefits of using seq_lseek() instead of
generic_file_llseek() are

* Early failure.  If traversing to certain file position should fail,
  seq_lseek() will report such failures on lseek(2) instead of the
  following read/write operations.

* EOF detection.  While SEEK_END is not supported, SEEK_SET/CUR +
  large offset can be used to detect eof - eof at the time of the seek
  anyway as the file size may change dynamically.

Both aren't necessary for sysfs or prospect kernfs users.  Revert to
genefic_file_llseek() and preserve the original behavior.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Link: https://lkml.kernel.org/r/20131031114358.GA5551@osirisTested-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Both POSIX.1-2008 and Linux Programmer's Manual have a dedicated return
error code for a case, when a file doesn't support mmap(), it's ENODEV.

This change replaces overloaded EINVAL with ENODEV in a situation
described above for sysfs binary files.
Signed-off-by: NVladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

3124eb16 ("sysfs: merge regular and bin file handling") folded bin
file handling into regular file handling.  Among other things, bin
file now shares the same open path including sysfs_open_dirent
association using sysfs_dirent->s_attr.open.  This is buggy because
->s_bin_attr lives in the same union and doesn't have the field.  This
bug doesn't trigger because sysfs_elem_bin_attr doesn't have an active
field at the conflicting position.  It does have a field "buffers" but
it isn't used anymore.

This patch collapses sysfs_elem_bin_attr into sysfs_elem_attr so that
the bin_attr is accessed through ->s_attr.bin_attr which lives with
->s_attr.attr in an anonymous union.  The code paths already assume
bin_attr contains attr as the first element, so this doesn't add any
more assumptions while making it explicit that the two types are
handled together.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Before patch(sysfs: prepare path write for unified regular / bin
file handling), when size of bin file is zero, writting still can
continue, but this patch changes the behaviour.

The worse thing is that firmware loader is broken by this patch,
and user space application can't write to firmware bin file any more
because both firmware loader and drivers can't know at advance how
large the firmware file is and have to set its initialized size as
zero.

This patch fixes the problem and keeps behaviour of writting to bin
as before.
Reported-by: NLothar Waßmann <LW@karo-electronics.de>
Tested-by: NLothar Waßmann <LW@karo-electronics.de>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

While looking at the code, I noticed that bin_attribute read() and write()
ops copy the inode size into an int for futher comparisons.

Some bin_attributes can be fairly large. For example, pci creates some for
BARs set to the BAR size and giant BARs are around the corner, so this is
going to break something somewhere eventually.

Let's use the right type.

[adjust for seqfile conversions, only needed for bin_read() - gkh]
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

375b611e ("sysfs: remove sysfs_buffer->ops") introduced
sysfs_file_ops() which determines the associated file operation of a
given sysfs_dirent.  As file ops access should be protected by an
active reference, the new function includes a lockdep assertion on the
sysfs_dirent; unfortunately, I forgot to take attr->ignore_lockdep
flag into account and the lockdep assertion trips spuriously for files
which opt out from active reference lockdep checking.

# cat /sys/devices/pci0000:00/0000:00:01.2/usb1/authorized

 ------------[ cut here ]------------
 WARNING: CPU: 1 PID: 540 at /work/os/work/fs/sysfs/file.c:79 sysfs_file_ops+0x4e/0x60()
 Modules linked in:
 CPU: 1 PID: 540 Comm: cat Not tainted 3.11.0-work+ #3
 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  0000000000000009 ffff880016205c08 ffffffff81ca0131 0000000000000000
  ffff880016205c40 ffffffff81096d0d ffff8800166cb898 ffff8800166f6f60
  ffffffff8125a220 ffff880011ab1ec0 ffff88000aff0c78 ffff880016205c50
 Call Trace:
  [<ffffffff81ca0131>] dump_stack+0x4e/0x82
  [<ffffffff81096d0d>] warn_slowpath_common+0x7d/0xa0
  [<ffffffff81096dea>] warn_slowpath_null+0x1a/0x20
  [<ffffffff8125994e>] sysfs_file_ops+0x4e/0x60
  [<ffffffff8125a274>] sysfs_open_file+0x54/0x300
  [<ffffffff811df612>] do_dentry_open.isra.17+0x182/0x280
  [<ffffffff811df820>] finish_open+0x30/0x40
  [<ffffffff811f0623>] do_last+0x503/0xd90
  [<ffffffff811f0f6b>] path_openat+0xbb/0x6d0
  [<ffffffff811f23ba>] do_filp_open+0x3a/0x90
  [<ffffffff811e09a9>] do_sys_open+0x129/0x220
  [<ffffffff811e0abe>] SyS_open+0x1e/0x20
  [<ffffffff81caf3c2>] system_call_fastpath+0x16/0x1b
 ---[ end trace aa48096b111dafdb ]---

Rename fs/sysfs/dir.c::ignore_lockdep() to sysfs_ignore_lockdep() and
move it to fs/sysfs/sysfs.h and make sysfs_file_ops() skip lockdep
assertion if sysfs_ignore_lockdep() is true.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

With the previous changes, sysfs regular file code is ready to handle
bin files too.  This patch makes bin files share the regular file
path.

* sysfs_create/remove_bin_file() are moved to fs/sysfs/file.c.

* sysfs_init_inode() is updated to use the new sysfs_bin_operations
  instead of bin_fops for bin files.

* fs/sysfs/bin.c and the related pieces are removed.

This patch shouldn't introduce any behavior difference to bin file
accesses.

Overall, this unification reduces the amount of duplicate logic, makes
behaviors more consistent and paves the road for building simpler and
more versatile interface which will allow other subsystems to make use
of sysfs for their pseudo filesystems.

v2: Stale fs/sysfs/bin.c reference dropped from
    Documentation/DocBook/filesystems.tmpl.  Reported by kbuild test
    robot.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay@vrfy.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs bin file handling will be merged into the regular file support.
This patch prepares the open path.

This patch updates sysfs_open_file() such that it can handle both
regular and bin files.

This is a preparation and the new bin file path isn't used yet.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs bin file handling will be merged into the regular file support.
This patch copies mmap support from bin so that fs/sysfs/file.c can
handle mmapping bin files.

The code is copied mostly verbatim with the following updates.

* ->mmapped and ->vm_ops are added to sysfs_open_file and bin_buffer
  references are replaced with sysfs_open_file ones.

* Symbols are prefixed with sysfs_.

* sysfs_unmap_bin_file() grabs sysfs_open_dirent and traverses
  ->files.  Invocation of this function is added to
  sysfs_addrm_finish().

* sysfs_bin_mmap() is added to sysfs_bin_operations.

This is a preparation and the new mmap path isn't used yet.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs bin file handling will be merged into the regular file support.
This patch prepares the read path.

Copy fs/sysfs/bin.c::read() to fs/sysfs/file.c and make it use
sysfs_open_file instead of bin_buffer.  The function is identical copy
except for the use of sysfs_open_file.

The new function is added to sysfs_bin_operations.  This isn't used
yet but will eventually replace fs/sysfs/bin.c.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs bin file handling will be merged into the regular file support.
This patch prepares the write path.

bin file write is almost identical to regular file write except that
the write length is capped by the inode size and @off is passed to the
write method.  This patch adds bin file handling to sysfs_write_file()
so that it can handle both regular and bin files.

A new file_operations struct sysfs_bin_operations is added, which
currently only hosts sysfs_write_file() and generic_file_llseek().
This isn't used yet but will eventually replace fs/sysfs/bin.c.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs read path implements its own buffering scheme between userland
and kernel callbacks, which essentially is a degenerate duplicate of
seq_file.  This patch replaces the custom read buffering
implementation in sysfs with seq_file.

While the amount of code reduction is small, this reduces low level
hairiness and enables future development of a new versatile API based
on seq_file so that sysfs features can be shared with other
subsystems.

As write path was already converted to not use sysfs_open_file->page,
this patch makes ->page and ->count unused and removes them.

Userland behavior remains the same except for some extreme corner
cases - e.g. sysfs will now regenerate the content each time a file is
read after a non-contiguous seek whereas the original code would keep
using the same content.  While this is a userland visible behavior
change, it is extremely unlikely to be noticeable and brings sysfs
behavior closer to that of procfs.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There isn't much to be gained by keeping around kernel buffer while a
file is open especially as the read path planned to be converted to
use seq_file and won't use the buffer.  This patch makes
sysfs_write_file() use per-write transient buffer instead of
sysfs_open_file->page.

This simplifies the write path, enables removing sysfs_open_file->page
once read path is updated and will help merging bin file write path
which already requires the use of a transient buffer due to a locking
order issue.

As the function comments of flush_write_buffer() and
sysfs_write_buffer() are being updated anyway, reformat them so that
they're more conventional.

v2: Use min_t() instead of min() in sysfs_write_file() to avoid build
    warning on arm.  Reported by build test robot.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs will be converted to use seq_file for read path, which will make
it difficult to pass around multiple pointers directly.  This patch
adds sysfs_open_file->sd and ->file so that we can reach all the
necessary data structures from sysfs_open_file.

flush_write_buffer() is updated to drop @dentry which was used to
discover the sysfs_dirent as it's now available through
sysfs_open_file->sd.

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

sysfs read path will be converted to use seq_file which will handle
buffering making sysfs_buffer a misnomer.  Rename sysfs_buffer to
sysfs_open_file, and sysfs_open_dirent->buffers to ->files.

This path is pure rename.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add a separate mutex to protect sysfs_open_dirent->buffers list.  This
will allow performing sleepable operations while traversing
sysfs_buffers, which will be renamed to sysfs_open_file.

Note that currently sysfs_open_dirent->buffers list isn't being used
for anything and this patch doesn't make any functional difference.
It will be used to merge regular and bin file supports.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, sysfs_ops is fetched during sysfs_open_file() and cached in
sysfs_buffer->ops to be used while the file is open.  This patch
removes the caching and makes each operation directly fetch sysfs_ops.

This patch doesn't introduce any behavior difference and is to prepare
for merging regular and bin file supports.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

->needs_read_fill is used to implement the following behaviors.

1. Ensure buffer filling on the first read.
2. Force buffer filling after a write.
3. Force buffer filling after a successful poll.

However, #2 and #3 don't really work as sysfs doesn't reset file
position.  While the read buffer would be refilled, the next read
would continue from the position after the last read or write,
requiring an explicit seek to the start for it to be useful, which
makes ->needs_read_fill superflous as read buffer is always refilled
if f_pos == 0.

Update sysfs_read_file() to test buffer->page for #1 instead and
remove ->needs_read_fill.  While this changes behavior in extreme
corner cases - e.g. re-reading a sysfs file after seeking to non-zero
position after a write or poll, it's highly unlikely to lead to actual
breakage.  This change is to prepare for using seq_file in the read
path.

While at it, reformat a comment in fill_write_buffer().
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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

sysfs_addrm_start/finish() enclose sysfs_dirent additions and
deletions and sysfs_addrm_cxt is used to record information necessary
to finish the operations.  Currently, sysfs_addrm_start() takes
@parent_sd, records it in sysfs_addrm_cxt, and assumes that all
operations in the block are performed under that @parent_sd.

This assumption has been fine until now but we want to make some
operations behave recursively and, while having @parent_sd recorded in
sysfs_addrm_cxt doesn't necessarily prevents that, it becomes
confusing.

This patch removes sysfs_addrm_cxt->parent_sd and makes
sysfs_add_one() take an explicit @parent_sd parameter.  Note that
sysfs_remove_one() doesn't need the extra argument as its parent is
always known from the target @sd.

While at it, add __acquires/releases() notations to
sysfs_addrm_start/finish() respectively.

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

Some internal sysfs functions which take explicit namespace argument
are weird in that they place the optional @ns in front of @name which
is contrary to the established convention.  This is confusing and
error-prone especially as @ns and @name may be interchanged without
causing compilation warning.

Swap the positions of @name and @ns in the following internal
functions.

 sysfs_find_dirent()
 sysfs_rename()
 sysfs_hash_and_remove()
 sysfs_name_hash()
 sysfs_name_compare()
 create_dir()

This patch doesn't introduce any functional changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The pre-existing sysfs interfaces which take explicit namespace
argument are weird in that they place the optional @ns in front of
@name which is contrary to the established convention.  For example,
we end up forcing vast majority of sysfs_get_dirent() users to do
sysfs_get_dirent(parent, NULL, name), which is silly and error-prone
especially as @ns and @name may be interchanged without causing
compilation warning.

This renames sysfs_get_dirent() to sysfs_get_dirent_ns() and swap the
positions of @name and @ns, and sysfs_get_dirent() is now a wrapper
around sysfs_get_dirent_ns().  This makes confusions a lot less
likely.

There are other interfaces which take @ns before @name.  They'll be
updated by following patches.

This patch doesn't introduce any functional changes.

v2: EXPORT_SYMBOL_GPL() wasn't updated leading to undefined symbol
    error on module builds.  Reported by build test robot.  Fixed.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs ns (namespace) implementation became more convoluted than
necessary while trying to hide ns information from visible interface.
The relatively recent attr ns support is a good example.

* attr ns tag is determined by sysfs_ops->namespace() callback while
  dir tag is determined by kobj_type->namespace().  The placement is
  arbitrary.

* Instead of performing operations with explicit ns tag, the namespace
  callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(),
  class_attr_namespace(), class_attr->namespace().  It's not simpler
  in any sense.  The only thing this convolution does is traversing
  the whole stack backwards.

The namespace callbacks are unncessary because the operations involved
are inherently synchronous.  The information can be provided in in
straight-forward top-down direction and reversing that direction is
unnecessary and against basic design principles.

This backward interface is unnecessarily convoluted and hinders
properly separating out sysfs from driver model / kobject for proper
layering.  This patch updates attr ns support such that

* sysfs_ops->namespace() and class_attr->namespace() are dropped.

* sysfs_{create|remove}_file_ns(), which take explicit @ns param, are
  added and sysfs_{create|remove}_file() are now simple wrappers
  around the ns aware functions.

* ns handling is dropped from sysfs_chmod_file().  Nobody uses it at
  this point.  sysfs_chmod_file_ns() can be added later if necessary.

* Explicit @ns is propagated through class_{create|remove}_file_ns()
  and netdev_class_{create|remove}_file_ns().

* driver/net/bonding which is currently the only user of attr
  namespace is updated to use netdev_class_{create|remove}_file_ns()
  with @bh->net as the ns tag instead of using the namespace callback.

This patch should be an equivalent conversion without any functional
difference.  It makes the code easier to follow, reduces lines of code
a bit and helps proper separation and layering.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This fixes the coding style warnings in fs/sysfs/file.c for broken
strings across lines.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This fixes the uaccess.h warnings in the sysfs.c files.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This fixes up the 80 column coding style issues in the sysfs .c files.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>