kernfs: Use RCU to access kernfs_node::name.

Using RCU lifetime rules to access kernfs_node::name can avoid the
trouble with kernfs_rename_lock in kernfs_name() and kernfs_path_from_node()
if the fs

kernfs: Use RCU to access kernfs_node::name.

Using RCU lifetime rules to access kernfs_node::name can avoid the
trouble with kernfs_rename_lock in kernfs_name() and kernfs_path_from_node()
if the fs was created with KERNFS_ROOT_INVARIANT_PARENT. This is usefull
as it allows to implement kernfs_path_from_node() only with RCU
protection and avoiding kernfs_rename_lock. The lock is only required if
the __parent node can be changed and the function requires an unchanged
hierarchy while it iterates from the node to its parent.
The change is needed to allow the lookup of the node's path
(kernfs_path_from_node()) from context which runs always with disabled
preemption and or interrutps even on PREEMPT_RT. The problem is that
kernfs_rename_lock becomes a sleeping lock on PREEMPT_RT.

I went through all ::name users and added the required access for the lookup
with a few extensions:
- rdtgroup_pseudo_lock_create() drops all locks and then uses the name
later on. resctrl supports rename with different parents. Here I made
a temporal copy of the name while it is used outside of the lock.

- kernfs_rename_ns() accepts NULL as new_parent. This simplifies
sysfs_move_dir_ns() where it can set NULL in order to reuse the current
name.

- kernfs_rename_ns() is only using kernfs_rename_lock if the parents are
different. All users use either kernfs_rwsem (for stable path view) or
just RCU for the lookup. The ::name uses always RCU free.

Use RCU lifetime guarantees to access kernfs_node::name.

Suggested-by: Tejun Heo <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Reported-by: [email protected]
Closes: https://lore.kernel.org/lkml/[email protected]/
Reported-by: Hillf Danton <[email protected]>
Closes: https://lore.kernel.org/[email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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fs/sysfs/dir.c : Fix typo in comment

Typo correction
kboject => kobject

Signed-off-by: Mukesh Ojha <[email protected]>
Link: https://lore.kernel.org/r/1698661274-32540-1-git-send-email-quic_mo

fs/sysfs/dir.c : Fix typo in comment

Typo correction
kboject => kobject

Signed-off-by: Mukesh Ojha <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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fs/sysfs/dir.c: replace S_IRWXU|S_IRUGO|S_IXUGO with 0755 sysfs_create_dir_ns()

If one ends up expanding on this line checkpatch will complain that the
combination S_IRWXU|S_IRUGO|S_IXUGO should jus

fs/sysfs/dir.c: replace S_IRWXU|S_IRUGO|S_IXUGO with 0755 sysfs_create_dir_ns()

If one ends up expanding on this line checkpatch will complain that the
combination S_IRWXU|S_IRUGO|S_IXUGO should just be replaced with the
octal 0755. Do that.

This makes no functional changes.

Signed-off-by: Luis Chamberlain <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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docs: filesystems: fix renamed references

Some filesystem references got broken by a previous patch
series I submitted. Address those.

Signed-off-by: Mauro Carvalho Chehab <[email protected]

docs: filesystems: fix renamed references

Some filesystem references got broken by a previous patch
series I submitted. Address those.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Acked-by: David Sterba <[email protected]> # fs/affs/Kconfig
Link: https://lore.kernel.org/r/57318c53008dbda7f6f4a5a9e5787f4d37e8565a.1586881715.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <[email protected]>

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sysfs: convert BUG_ON to WARN_ON

It's rude to crash the system just because the developer did something
wrong, as it prevents them from usually even seeing what went wrong.

So convert the few BUG_O

sysfs: convert BUG_ON to WARN_ON

It's rude to crash the system just because the developer did something
wrong, as it prevents them from usually even seeing what went wrong.

So convert the few BUG_ON() calls that have snuck into the sysfs code
over the years to WARN_ON() to make it more "friendly". All of these
are able to be recovered from, so it makes no sense to crash.

Reported-by: Linus Torvalds <[email protected]>
Reviewed-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kobject: allow creating kobject belonging to arbitrary users

Normally kobjects and their sysfs representation belong to global root,
however it is not necessarily the case for objects in sepa

sysfs, kobject: allow creating kobject belonging to arbitrary users

Normally kobjects and their sysfs representation belong to global root,
however it is not necessarily the case for objects in separate namespaces.
For example, objects in separate network namespace logically belong to the
container's root and not global root.

This change lays groundwork for allowing network namespace objects
ownership to be transferred to container's root user by defining
get_ownership() callback in ktype structure and using it in sysfs code to
retrieve desired uid/gid when creating sysfs objects for given kobject.

Co-Developed-by: Tyler Hicks <[email protected]>
Signed-off-by: Dmitry Torokhov <[email protected]>
Signed-off-by: Tyler Hicks <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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kernfs: allow creating kernfs objects with arbitrary uid/gid

This change allows creating kernfs files and directories with arbitrary
uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending

kernfs: allow creating kernfs objects with arbitrary uid/gid

This change allows creating kernfs files and directories with arbitrary
uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending
kernfs_create_dir_ns() and kernfs_create_file_ns() with uid/gid arguments.
The "simple" kernfs_create_file() and kernfs_create_dir() are left alone
and always create objects belonging to the global root.

When creating symlinks ownership (uid/gid) is taken from the target kernfs
object.

Co-Developed-by: Tyler Hicks <[email protected]>
Signed-off-by: Dmitry Torokhov <[email protected]>
Signed-off-by: Tyler Hicks <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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sysfs: remove DEBUG defines

It isn't needed at all in these files, dynamic debug is the best way to
enable this type of thing, if you really want it. As it is, these
defines were not doing anything

sysfs: remove DEBUG defines

It isn't needed at all in these files, dynamic debug is the best way to
enable this type of thing, if you really want it. As it is, these
defines were not doing anything at all.

Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: use SPDX identifiers

Move the license "mark" of the sysfs files to be in SPDX form, instead
of the custom text that it currently is in. This is in a quest to get
rid of the 700+ different wa

sysfs: use SPDX identifiers

Move the license "mark" of the sysfs files to be in SPDX form, instead
of the custom text that it currently is in. This is in a quest to get
rid of the 700+ different ways we say "GPLv2" in the kernel tree.

Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs: turn WARN() into pr_warn()

It's not good to crash the machine if panic_on_warn() is set just
because someone made a stupid mistake of trying to create a sysfs file
with the same name of an ex

sysfs: turn WARN() into pr_warn()

It's not good to crash the machine if panic_on_warn() is set just
because someone made a stupid mistake of trying to create a sysfs file
with the same name of an existing one. This makes the automated testing
tools a lot harder to find the real bugs in the kernel.

So just print a warning out and dump the stack to get the attention of
the developer that they did something foolish. Then keep on trucking,
as this should not be a fatal error at all.

Reported-by: Dmitry Vyukov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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kernfs: make kernfs_path*() behave in the style of strlcpy()

kernfs_path*() functions always return the length of the full path but
the path content is undefined if the length is larger than the
pro

kernfs: make kernfs_path*() behave in the style of strlcpy()

kernfs_path*() functions always return the length of the full path but
the path content is undefined if the length is larger than the
provided buffer. This makes its behavior different from strlcpy() and
requires error handling in all its users even when they don't care
about truncation. In addition, the implementation can actully be
simplified by making it behave properly in strlcpy() style.

* Update kernfs_path_from_node_locked() to always fill up the buffer
with path. If the buffer is not large enough, the output is
truncated and terminated.

* kernfs_path() no longer needs error handling. Make it a simple
inline wrapper around kernfs_path_from_node().

* sysfs_warn_dup()'s use of kernfs_path() doesn't need error handling.
Updated accordingly.

* cgroup_path()'s use of kernfs_path() updated to retain the old
behavior.

Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Serge Hallyn <[email protected]>

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sysfs: Add support for permanently empty directories to serve as mount points.

Add two functions sysfs_create_mount_point and
sysfs_remove_mount_point that hang a permanently empty directory off
of

sysfs: Add support for permanently empty directories to serve as mount points.

Add two functions sysfs_create_mount_point and
sysfs_remove_mount_point that hang a permanently empty directory off
of a kobject or remove a permanently emptpy directory hanging from a
kobject. Export these new functions so modular filesystems can use
them.

Cc: [email protected]
Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: "Eric W. Biederman" <[email protected]>

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kernfs: implement kernfs_get_parent(), kernfs_name/path() and friends

kernfs_node->parent and ->name are currently marked as "published"
indicating that kernfs users may access them directly; howeve

kernfs: implement kernfs_get_parent(), kernfs_name/path() and friends

kernfs_node->parent and ->name are currently marked as "published"
indicating that kernfs users may access them directly; however, those
fields may get updated by kernfs_rename[_ns]() and unrestricted access
may lead to erroneous values or oops.

Protect ->parent and ->name updates with a irq-safe spinlock
kernfs_rename_lock and implement the following accessors for these
fields.

* kernfs_name() - format the node's name into the specified buffer
* kernfs_path() - format the node's path into the specified buffer
* pr_cont_kernfs_name() - pr_cont a node's name (doesn't need buffer)
* pr_cont_kernfs_path() - pr_cont a node's path (doesn't need buffer)
* kernfs_get_parent() - pin and return a node's parent

All can be called under any context. The recursive sysfs_pathname()
in fs/sysfs/dir.c is replaced with kernfs_path() and
sysfs_rename_dir_ns() is updated to use kernfs_get_parent() instead of
dereferencing parent directly.

v2: Dummy definition of kernfs_path() for !CONFIG_KERNFS was missing
static inline making it cause a lot of build warnings. Add it.

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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kernfs: add @mode to kernfs_create_dir[_ns]()

sysfs assumed 0755 for all newly created directories and kernfs
inherited it. This assumption is unnecessarily restrictive and
inconsistent with kernfs

kernfs: add @mode to kernfs_create_dir[_ns]()

sysfs assumed 0755 for all newly created directories and kernfs
inherited it. This assumption is unnecessarily restrictive and
inconsistent with kernfs_create_file[_ns](). This patch adds @mode
parameter to kernfs_create_dir[_ns]() and update uses in sysfs
accordingly. Among others, this will be useful for implementations of
the planned ->mkdir() method.

This patch doesn't introduce any behavior differences.

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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kernfs: s/sysfs/kernfs/ in constants

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

kernfs: s/sysfs/kernfs/ in constants

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: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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kernfs: drop s_ prefix from kernfs_node members

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 chan

kernfs: drop s_ prefix from kernfs_node members

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: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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

kernfs has just been separated out from sysfs and we're already in
full conflict mode. Nothing can make the situation any wors

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

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 <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Ashutosh Dixit <[email protected]>
Cc: kbuild test robot <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kernfs: introduce sysfs_root_sd

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

sysfs, kernfs: introduce sysfs_root_sd

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 <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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

Move core dir code to fs/kernfs/dir.c. fs/sysfs/dir.c now only
contains sysfs_warn_dup() and sysfs wrappers around kernfs interfaces.
The respec

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

Move core dir code to fs/kernfs/dir.c. fs/sysfs/dir.c now only
contains sysfs_warn_dup() and sysfs wrappers around kernfs interfaces.
The respective declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

v2: sysfs_symlink_target_lock was mistakenly relocated to kernfs. It
should remain with sysfs. Fixed.

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kernfs: introduce kernfs[_find_and]_get() and kernfs_put()

Introduce kernfs interface for finding, getting and putting
sysfs_dirents.

* sysfs_find_dirent() is renamed to kernfs_find_ns() and

sysfs, kernfs: introduce kernfs[_find_and]_get() and kernfs_put()

Introduce kernfs interface for finding, getting and putting
sysfs_dirents.

* sysfs_find_dirent() is renamed to kernfs_find_ns() and lockdep
assertion for sysfs_mutex is added.

* sysfs_get_dirent_ns() is renamed to kernfs_find_and_get().

* Macro inline dancing around __sysfs_get/put() are removed and
kernfs_get/put() are made proper functions implemented in
fs/sysfs/dir.c.

While the conversions are mostly equivalent, there's one difference -
kernfs_get() doesn't return the input param as its return value. This
change is intentional. While passing through the input increases
writability in some areas, it is unnecessary and has been shown to
cause confusion regarding how the last ref is handled.

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kernfs: revamp sysfs_dirent active_ref lockdep annotation

Currently, sysfs_dirent active_ref lockdep annotation uses
attribute->[s]key as the lockdep key, which forces
kernfs_create_file_ns()

sysfs, kernfs: revamp sysfs_dirent active_ref lockdep annotation

Currently, sysfs_dirent active_ref lockdep annotation uses
attribute->[s]key as the lockdep key, which forces
kernfs_create_file_ns() to assume that sysfs_dirent->priv is pointing
to a struct attribute which may not be true for non-sysfs users. This
patch restructures the lockdep annotation such that

* kernfs_ops contains lockdep_key which is used by default for files
created kernfs_create_file_ns().

* kernfs_create_file_ns_key() is introduced which takes an extra @key
argument. The created file will use the specified key for
active_ref lockdep annotation. If NULL is specified, lockdep for
the file is disabled.

* sysfs_add_file_mode_ns() is updated to use
kernfs_create_file_ns_key() with the appropriate key from the
attribute or NULL if ignore_lockdep is set.

This makes the lockdep annotation properly contained in kernfs while
allowing sysfs to cleanly keep its current behavior. This patch
doesn't introduce any behavior differences.

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kernfs: remove sysfs_add_one()

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 conv

sysfs, kernfs: remove sysfs_add_one()

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: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kernfs: introduce kernfs_create_dir[_ns]()

Introduce kernfs interface to manipulate a directory which takes and
returns sysfs_dirents.

create_dir() is renamed to kernfs_create_dir_ns() and i

sysfs, kernfs: introduce kernfs_create_dir[_ns]()

Introduce kernfs interface to manipulate a directory which takes and
returns sysfs_dirents.

create_dir() is renamed to kernfs_create_dir_ns() and its argumantes
and return value are updated. create_dir() usages are replaced with
kernfs_create_dir_ns() and sysfs_create_subdir() usages are replaced
with kernfs_create_dir(). Dup warnings are handled explicitly by
sysfs users of the kernfs interface.

sysfs_enable_ns() is renamed to kernfs_enable_ns().

This patch doesn't introduce any behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

v3: kernfs_enable_ns() added.

v4: Refreshed on top of "sysfs: drop kobj_ns_type handling, take #2"
so that this patch removes sysfs_enable_ns().

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kernfs: replace sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with ->priv

A directory sysfs_dirent points to the associated kobj. A regular or
bin file points to the associated [bin_]attr

sysfs, kernfs: replace sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with ->priv

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: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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sysfs, kernfs: introduce kernfs_rename[_ns]()

Introduce kernfs rename interface, krenfs_rename[_ns]().

This is just rename of sysfs_rename(). No functional changes.
Function comment is added to ke

sysfs, kernfs: introduce kernfs_rename[_ns]()

Introduce kernfs rename interface, krenfs_rename[_ns]().

This is just rename of sysfs_rename(). No functional changes.
Function comment is added to kernfs_rename_ns() and @new_parent_sd is
renamed to @new_parent for consistency with other kernfs interfaces.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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