[PATCHSET driver-core-next] sysfs: separate out kernfs, take #2

Tejun Heo
2013-11-03T09:53:25Z

Hello, guys.

(This is for 3.14-rc1. Posting early for review. Will refresh and
repost once the next driver-core-next opens.)

This is the second take of the patchset to separate out kernfs from
sysfs.

Changes from the last take[L] are,

* Patches applied to driver-core-next are dropped and the rest are
refreshed.

* Mount portion of kernfs implemented. kernfs now supports multiple
sysfs_dirent hierarchies and sysfs is just one of them.

* Dummy interface for kernfs for !CONFIG_SYSFS updated to return
-ENOSYS / ERR_PTR(-ENOSYS) where applicable.

* Several bug fixes.

This patchset contains 39 patches to separate out core sysfs features
into kernfs. kernfs exclusively deals with sysfs_dirent, which will
be later renamed to kernfs_node, and kernfs_ops. sysfs becomes a
wrapping layer over sysfs which interfaces kobject and
[bin_]attribute.

The goal of these changes is to allow other users to make use of the
core features of sysfs instead of rolling their own pseudo filesystem
implementation which usually fails to deal with issues with file
shutdowns, locking separation from vfs layer and so on. This patchset
refactors sysfs and separates out core functionalities to kernfs.
After the patchset, kernfs is fully functional - multiple sysfs_dirent
hierarchies can be created and mounted and sysfs is just one user of
kernfs.

This patchset shouldn't introduce any behavior differences and
contains the following patches.

0001-sysfs-make-__sysfs_add_one-fail-if-the-parent-isn-t-.patch
0002-sysfs-kernfs-add-skeletons-for-kernfs.patch
0003-sysfs-kernfs-introduce-kernfs_remove-_by_name-_ns.patch
0004-sysfs-kernfs-introduce-kernfs_create_link.patch
0005-sysfs-kernfs-introduce-kernfs_rename-_ns.patch
0006-sysfs-kernfs-introduce-kernfs_setattr.patch
0007-sysfs-kernfs-replace-sysfs_dirent-s_dir.kobj-and-s_a.patch
0008-sysfs-kernfs-introduce-kernfs_create_dir-_ns.patch
0009-sysfs-kernfs-prepare-read-path-for-kernfs.patch
0010-sysfs-kernfs-prepare-write-path-for-kernfs.patch
0011-sysfs-kernfs-prepare-mmap-path-for-kernfs.patch
0012-sysfs-kernfs-prepare-open-release-poll-paths-for-ker.patch
0013-sysfs-kernfs-move-sysfs_open_file-to-include-linux-k.patch
0014-sysfs-kernfs-introduce-kernfs_ops.patch
0015-sysfs-kernfs-add-sysfs_dirent-s_attr.size.patch
0016-sysfs-kernfs-remove-SYSFS_KOBJ_BIN_ATTR.patch
0017-sysfs-kernfs-introduce-kernfs_create_file-_ns.patch
0018-sysfs-kernfs-remove-sysfs_add_one.patch
0019-sysfs-kernfs-add-kernfs_ops-seq_-start-next-stop.patch
0020-sysfs-kernfs-introduce-kernfs_notify.patch
0021-sysfs-kernfs-reorganize-SYSFS_-constants.patch
0022-sysfs-kernfs-revamp-sysfs_dirent-active_ref-lockdep-.patch
0023-sysfs-kernfs-introduce-kernfs-_find_and-_get-and-ker.patch
0024-sysfs-kernfs-move-internal-decls-to-fs-kernfs-kernfs.patch
0025-sysfs-kernfs-move-inode-code-to-fs-kernfs-inode.c.patch
0026-sysfs-kernfs-move-dir-core-code-to-fs-kernfs-dir.c.patch
0027-sysfs-kernfs-move-file-core-code-to-fs-kernfs-file.c.patch
0028-sysfs-kernfs-move-symlink-core-code-to-fs-kernfs-sym.patch
0029-sysfs-kernfs-drop-unused-params-from-sysfs_fill_supe.patch
0030-sysfs-kernfs-make-sysfs_super_info-ns-const.patch
0031-sysfs-kernfs-no-need-to-kern_mount-sysfs-from-sysfs_.patch
0032-sysfs-kernfs-introduce-sysfs_root_sd.patch
0033-sysfs-kernfs-implement-kernfs_create-destroy_root.patch
0034-sysfs-kernfs-make-inode-number-ida-per-kernfs_root.patch
0035-sysfs-kernfs-make-super_blocks-bind-to-different-ker.patch
0036-sysfs-kernfs-prepare-mount-path-for-kernfs.patch
0037-sysfs-kernfs-move-mount-core-code-to-fs-kernfs-mount.patch
0038-sysfs-kernfs-make-sysfs_dirent-definition-public.patch
0039-sysfs-kernfs-remove-cross-inclusions-of-internal-hea.patch

0001 is prep patch.

0002 preps fs/kernfs/ directory with skeleton files.

0003-0023 refactor various code paths so that all externally visible
interfaces are split to core kernfs interface which deals with
sysfs_dirent and kernfs_ops and sysfs wrapping it to provide the
existing interface.

0024-0028 move kernfs part of the implementation under fs/kernfs.

0029-0035 update mount logic so that it can support multiple
sysfs_dirent hierarchies instead of assuming single sysfs hierarchy.

0036-0037 refactor mount code path for kernfs and moves kernfs
interface and implementation to fs/kernfs.

0038-0039 cut the remaining entanglement between sysfs and kernfs and
make the former proper user of the latter.

Multiple hierarchy support tested with the attached module (needs
adding EXPORT_SYMBOL to kernfs interface). Works as expected.

This patchset is on top of

driver-core-next 0cae60f91494 ("sysfs: rename sysfs_assoc_lock and explain what it's about")

The patches are also available in the following git branch.

git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-separate-out-kernfs

diffstat follows. Thanks.

fs/Makefile | 2
fs/kernfs/Makefile | 5
fs/kernfs/dir.c | 1007 ++++++++++++++++++++++++++++++++++++++++++++
fs/kernfs/file.c | 797 ++++++++++++++++++++++++++++++++++
fs/kernfs/inode.c | 337 ++++++++++++++
fs/kernfs/kernfs-internal.h | 124 +++++
fs/kernfs/mount.c | 165 +++++++
fs/kernfs/symlink.c | 148 ++++++
fs/namespace.c | 2
fs/sysfs/Makefile | 2
fs/sysfs/dir.c | 990 -------------------------------------------
fs/sysfs/file.c | 913 +++++++--------------------------------
fs/sysfs/group.c | 59 +-
fs/sysfs/inode.c | 331 --------------
fs/sysfs/mount.c | 166 -------
fs/sysfs/symlink.c | 162 -------
fs/sysfs/sysfs.h | 217 ---------
include/linux/kernfs.h | 311 +++++++++++++
include/linux/sysfs.h | 43 -
19 files changed, 3174 insertions(+), 2607 deletions(-)

--
tejun

[L] https://lkml.kernel.org/g/1382629780-10006-1-git-send-email-tj@kernel.org