linux/fs/sysfs
Tejun Heo f6acf8bb6a sysfs, kernfs: introduce kernfs_ops
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: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29 17:35:05 -08:00
..
dir.c sysfs, kernfs: introduce kernfs_create_dir[_ns]() 2013-11-29 17:20:13 -08:00
file.c sysfs, kernfs: introduce kernfs_ops 2013-11-29 17:35:05 -08:00
group.c sysfs, kernfs: introduce kernfs_create_dir[_ns]() 2013-11-29 17:20:13 -08:00
inode.c sysfs, kernfs: prepare open, release, poll paths for kernfs 2013-11-29 17:35:05 -08:00
Kconfig kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
Makefile sysfs: merge regular and bin file handling 2013-10-05 17:27:40 -07:00
mount.c sysfs: drop kobj_ns_type handling, take #2 2013-11-27 13:01:03 -08:00
symlink.c sysfs, kernfs: replace sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with ->priv 2013-11-29 17:19:16 -08:00
sysfs.h sysfs, kernfs: introduce kernfs_ops 2013-11-29 17:35:05 -08:00