Merge tag 'v6.8-rc4' into x86/percpu, to resolve conflicts and refresh the branch

Conflicts:
arch/x86/include/asm/percpu.h
arch/x86/include/asm/text-patching.h

Signed-off-by: Ingo Molnar <mingo@k

Merge tag 'v6.8-rc4' into x86/percpu, to resolve conflicts and refresh the branch

Conflicts:
arch/x86/include/asm/percpu.h
arch/x86/include/asm/text-patching.h

Signed-off-by: Ingo Molnar <mingo@kernel.org>

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Merge tag 'drm-misc-next-2024-02-08' into msm-next

Merge the drm-misc tree to uprev MSM CI.

Signed-off-by: Rob Clark <robdclark@chromium.org>

Merge drm/drm-next into drm-misc-next

Kickstart 6.9 development cycle.

Signed-off-by: Maxime Ripard <mripard@kernel.org>

Merge branch 'linus' into x86/mm, to refresh the branch and pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge drm/drm-next into drm-xe-next

Sync to v6.8-rc1.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Merge v6.8-rc1 into drm-misc-fixes

Let's kickstart the 6.8 fix cycle.

Signed-off-by: Maxime Ripard <mripard@kernel.org>

Merge branch 'master' into mm-hotfixes-stable

Merge drm/drm-next into drm-intel-next

Backmerge to bring Xe driver to drm-intel-next.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Merge tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull dcache updates from Al Viro:
"Change of locking rules for __dentry_kill(), regularized refcounting
rules in

Merge tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull dcache updates from Al Viro:
"Change of locking rules for __dentry_kill(), regularized refcounting
rules in that area, assorted cleanups and removal of weird corner
cases (e.g. now ->d_iput() on child is always called before the parent
might hit __dentry_kill(), etc)"

* tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (40 commits)
dcache: remove unnecessary NULL check in dget_dlock()
kill DCACHE_MAY_FREE
__d_unalias() doesn't use inode argument
d_alloc_parallel(): in-lookup hash insertion doesn't need an RCU variant
get rid of DCACHE_GENOCIDE
d_genocide(): move the extern into fs/internal.h
simple_fill_super(): don't bother with d_genocide() on failure
nsfs: use d_make_root()
d_alloc_pseudo(): move setting ->d_op there from the (sole) caller
kill d_instantate_anon(), fold __d_instantiate_anon() into remaining caller
retain_dentry(): introduce a trimmed-down lockless variant
__dentry_kill(): new locking scheme
d_prune_aliases(): use a shrink list
switch select_collect{,2}() to use of to_shrink_list()
to_shrink_list(): call only if refcount is 0
fold dentry_kill() into dput()
don't try to cut corners in shrink_lock_dentry()
fold the call of retain_dentry() into fast_dput()
Call retain_dentry() with refcount 0
dentry_kill(): don't bother with retain_dentry() on slow path
...

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Merge tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull rename updates from Al Viro:
"Fix directory locking scheme on rename

This was broken in 6.5; we really can'

Merge tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull rename updates from Al Viro:
"Fix directory locking scheme on rename

This was broken in 6.5; we really can't lock two unrelated directories
without holding ->s_vfs_rename_mutex first and in case of same-parent
rename of a subdirectory 6.5 ends up doing just that"

* tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
rename(): avoid a deadlock in the case of parents having no common ancestor
kill lock_two_inodes()
rename(): fix the locking of subdirectories
f2fs: Avoid reading renamed directory if parent does not change
ext4: don't access the source subdirectory content on same-directory rename
ext2: Avoid reading renamed directory if parent does not change
udf_rename(): only access the child content on cross-directory rename
ocfs2: Avoid touching renamed directory if parent does not change
reiserfs: Avoid touching renamed directory if parent does not change

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Merge branch 'for-6.8/amd-sfh' into for-linus

- addition of new interfaces to export User presence information and
Ambient light from amd-sfh to other drivers within the kernel (Basavaraj
Natika

Merge branch 'for-6.8/amd-sfh' into for-linus

- addition of new interfaces to export User presence information and
Ambient light from amd-sfh to other drivers within the kernel (Basavaraj
Natikar)

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Merge tag 'vfs-6.8.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs super updates from Christian Brauner:
"This contains the super work for this cycle including the long-awa

Merge tag 'vfs-6.8.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs super updates from Christian Brauner:
"This contains the super work for this cycle including the long-awaited
series by Jan to make it possible to prevent writing to mounted block
devices:

- Writing to mounted devices is dangerous and can lead to filesystem
corruption as well as crashes. Furthermore syzbot comes with more
and more involved examples how to corrupt block device under a
mounted filesystem leading to kernel crashes and reports we can do
nothing about. Add tracking of writers to each block device and a
kernel cmdline argument which controls whether other writeable
opens to block devices open with BLK_OPEN_RESTRICT_WRITES flag are
allowed.

Note that this effectively only prevents modification of the
particular block device's page cache by other writers. The actual
device content can still be modified by other means - e.g. by
issuing direct scsi commands, by doing writes through devices lower
in the storage stack (e.g. in case loop devices, DM, or MD are
involved) etc. But blocking direct modifications of the block
device page cache is enough to give filesystems a chance to perform
data validation when loading data from the underlying storage and
thus prevent kernel crashes.

Syzbot can use this cmdline argument option to avoid uninteresting
crashes. Also users whose userspace setup does not need writing to
mounted block devices can set this option for hardening. We expect
that this will be interesting to quite a few workloads.

Btrfs is currently opted out of this because they still haven't
merged patches we require for this to work from three kernel
releases ago.

- Reimplement block device freezing and thawing as holder operations
on the block device.

This allows us to extend block device freezing to all devices
associated with a superblock and not just the main device. It also
allows us to remove get_active_super() and thus another function
that scans the global list of superblocks.

Freezing via additional block devices only works if the filesystem
chooses to use @fs_holder_ops for these additional devices as well.
That currently only includes ext4 and xfs.

Earlier releases switched get_tree_bdev() and mount_bdev() to use
@fs_holder_ops. The remaining nilfs2 open-coded version of
mount_bdev() has been converted to rely on @fs_holder_ops as well.
So block device freezing for the main block device will continue to
work as before.

There should be no regressions in functionality. The only special
case is btrfs where block device freezing for the main block device
never worked because sb->s_bdev isn't set. Block device freezing
for btrfs can be fixed once they can switch to @fs_holder_ops but
that can happen whenever they're ready"

* tag 'vfs-6.8.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (27 commits)
block: Fix a memory leak in bdev_open_by_dev()
super: don't bother with WARN_ON_ONCE()
super: massage wait event mechanism
ext4: Block writes to journal device
xfs: Block writes to log device
fs: Block writes to mounted block devices
btrfs: Do not restrict writes to btrfs devices
block: Add config option to not allow writing to mounted devices
block: Remove blkdev_get_by_*() functions
bcachefs: Convert to bdev_open_by_path()
fs: handle freezing from multiple devices
fs: remove dead check
nilfs2: simplify device handling
fs: streamline thaw_super_locked
ext4: simplify device handling
xfs: simplify device handling
fs: simplify setup_bdev_super() calls
blkdev: comment fs_holder_ops
porting: document block device freeze and thaw changes
fs: remove unused helper
...

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Merge remote-tracking branch 'torvalds/master' into perf-tools-next

To pick up fixes that went thru perf-tools for v6.7 and to get in sync
with upstream to check for drift in the copies of headers,

Merge remote-tracking branch 'torvalds/master' into perf-tools-next

To pick up fixes that went thru perf-tools for v6.7 and to get in sync
with upstream to check for drift in the copies of headers, etc.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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rename(): avoid a deadlock in the case of parents having no common ancestor

... and fix the directory locking documentation and proof of correctness.
Holding ->s_vfs_rename_mutex *almost* prevents -

rename(): avoid a deadlock in the case of parents having no common ancestor

... and fix the directory locking documentation and proof of correctness.
Holding ->s_vfs_rename_mutex *almost* prevents ->d_parent changes; the
case where we really don't want it is splicing the root of disconnected
tree to somewhere.

In other words, ->s_vfs_rename_mutex is sufficient to stabilize "X is an
ancestor of Y" only if X and Y are already in the same tree. Otherwise
it can go from false to true, and one can construct a deadlock on that.

Make lock_two_directories() report an error in such case and update the
callers of lock_rename()/lock_rename_child() to handle such errors.

And yes, such conditions are not impossible to create ;-/

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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rename(): fix the locking of subdirectories

We should never lock two subdirectories without having taken
->s_vfs_rename_mutex; inode pointer order or not, the "order" proposed
in 28eceeda130f "fs:

rename(): fix the locking of subdirectories

We should never lock two subdirectories without having taken
->s_vfs_rename_mutex; inode pointer order or not, the "order" proposed
in 28eceeda130f "fs: Lock moved directories" is not transitive, with
the usual consequences.

The rationale for locking renamed subdirectory in all cases was
the possibility of race between rename modifying .. in a subdirectory to
reflect the new parent and another thread modifying the same subdirectory.
For a lot of filesystems that's not a problem, but for some it can lead
to trouble (e.g. the case when short directory contents is kept in the
inode, but creating a file in it might push it across the size limit
and copy its contents into separate data block(s)).

However, we need that only in case when the parent does change -
otherwise ->rename() doesn't need to do anything with .. entry in the
first place. Some instances are lazy and do a tautological update anyway,
but it's really not hard to avoid.

Amended locking rules for rename():
find the parent(s) of source and target
if source and target have the same parent
lock the common parent
else
lock ->s_vfs_rename_mutex
lock both parents, in ancestor-first order; if neither
is an ancestor of another, lock the parent of source
first.
find the source and target.
if source and target have the same parent
if operation is an overwriting rename of a subdirectory
lock the target subdirectory
else
if source is a subdirectory
lock the source
if target is a subdirectory
lock the target
lock non-directories involved, in inode pointer order if both
source and target are such.

That way we are guaranteed that parents are locked (for obvious reasons),
that any renamed non-directory is locked (nfsd relies upon that),
that any victim is locked (emptiness check needs that, among other things)
and subdirectory that changes parent is locked (needed to protect the update
of .. entries). We are also guaranteed that any operation locking more
than one directory either takes ->s_vfs_rename_mutex or locks a parent
followed by its child.

Cc: stable@vger.kernel.org
Fixes: 28eceeda130f "fs: Lock moved directories"
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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Merge branches 'work.dcache-misc' and 'work.dcache2' into work.dcache

__dentry_kill(): new locking scheme

Currently we enter __dentry_kill() with parent (along with the victim
dentry and victim's inode) held locked. Then we
mark dentry refcount as dead
call ->d_pru

__dentry_kill(): new locking scheme

Currently we enter __dentry_kill() with parent (along with the victim
dentry and victim's inode) held locked. Then we
mark dentry refcount as dead
call ->d_prune()
remove dentry from hash
remove it from the parent's list of children
unlock the parent, don't need it from that point on
detach dentry from inode, unlock dentry and drop the inode
(via ->d_iput())
call ->d_release()
regain the lock on dentry
check if it's on a shrink list (in which case freeing its empty husk
has to be left to shrink_dentry_list()) or not (in which case we can free it
ourselves). In the former case, mark it as an empty husk, so that
shrink_dentry_list() would know it can free the sucker.
drop the lock on dentry
... and usually the caller proceeds to drop a reference on the parent,
possibly retaking the lock on it.

That is painful for a bunch of reasons, starting with the need to take locks
out of order, but not limited to that - the parent of positive dentry can
change if we drop its ->d_lock, so getting these locks has to be done with
care. Moreover, as soon as dentry is out of the parent's list of children,
shrink_dcache_for_umount() won't see it anymore, making it appear as if
the parent is inexplicably busy. We do work around that by having
shrink_dentry_list() decrement the parent's refcount first and put it on
shrink list to be evicted once we are done with __dentry_kill() of child,
but that may in some cases lead to ->d_iput() on child called after the
parent got killed. That doesn't happen in cases where in-tree ->d_iput()
instances might want to look at the parent, but that's brittle as hell.

Solution: do removal from the parent's list of children in the very
end of __dentry_kill(). As the result, the callers do not need to
lock the parent and by the time we really need the parent locked,
dentry is negative and is guaranteed not to be moved around.

It does mean that ->d_prune() will be called with parent not locked.
It also means that we might see dentries in process of being torn
down while going through the parent's list of children; those dentries
will be unhashed, negative and with refcount marked dead. In practice,
that's enough for in-tree code that looks through the list of children
to do the right thing as-is. Out-of-tree code might need to be adjusted.

Calling conventions: __dentry_kill(dentry) is called with dentry->d_lock
held, along with ->i_lock of its inode (if any). It either returns
the parent (locked, with refcount decremented to 0) or NULL (if there'd
been no parent or if refcount decrement for parent hadn't reached 0).

lock_for_kill() is adjusted for new requirements - it doesn't touch
the parent's ->d_lock at all.

Callers adjusted. Note that for dput() we don't need to bother with
fast_dput() for the parent - we just need to check retain_dentry()
for it, since its ->d_lock is still held since the moment when
__dentry_kill() had taken it to remove the victim from the list of
children.

The kludge with early decrement of parent's refcount in
shrink_dentry_list() is no longer needed - shrink_dcache_for_umount()
sees the half-killed dentries in the list of children for as long
as they are pinning the parent. They are easily recognized and
accounted for by select_collect(), so we know we are not done yet.

As the result, we always have the expected ordering for ->d_iput()/->d_release()
vs. __dentry_kill() of the parent, no exceptions. Moreover, the current
rules for shrink lists (one must make sure that shrink_dcache_for_umount()
won't happen while any dentries from the superblock in question are on
any shrink lists) are gone - shrink_dcache_for_umount() will do the
right thing in all cases, taking such dentries out. Their empty
husks (memory occupied by struct dentry itself + its external name,
if any) will remain on the shrink lists, but they are no obstacles
to filesystem shutdown. And such husks will get freed as soon as
shrink_dentry_list() of the list they are on gets to them.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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Call retain_dentry() with refcount 0

Instead of bumping it from 0 to 1, calling retain_dentry(), then
decrementing it back to 0 (with ->d_lock held all the way through),
just leave refcount at 0 thr

Call retain_dentry() with refcount 0

Instead of bumping it from 0 to 1, calling retain_dentry(), then
decrementing it back to 0 (with ->d_lock held all the way through),
just leave refcount at 0 through all of that.

It will have a visible effect for ->d_delete() - now it can be
called with refcount 0 instead of 1 and it can no longer play
silly buggers with dropping/regaining ->d_lock. Not that any
in-tree instances tried to (it's pretty hard to get right).

Any out-of-tree ones will have to adjust (assuming they need any
changes).

Note that we do not need to extend rcu-critical area here - we have
verified that refcount is non-negative after having grabbed ->d_lock,
so nobody will be able to free dentry until they get into __dentry_kill(),
which won't happen until they manage to grab ->d_lock.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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dentry: switch the lists of children to hlist

Saves a pointer per struct dentry and actually makes the things less
clumsy. Cleaned the d_walk() and dcache_readdir() a bit by use
of hlist_for_... it

dentry: switch the lists of children to hlist

Saves a pointer per struct dentry and actually makes the things less
clumsy. Cleaned the d_walk() and dcache_readdir() a bit by use
of hlist_for_... iterators.

A couple of new helpers - d_first_child() and d_next_sibling(),
to make the expressions less awful.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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Merge tag 'thunderbolt-for-v6.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt into usb-linus

Mika writes:

thunderbolt: Fixes for v6.7-rc3

This includes following USB4/T

Merge tag 'thunderbolt-for-v6.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt into usb-linus

Mika writes:

thunderbolt: Fixes for v6.7-rc3

This includes following USB4/Thunderbolt fixes for v6.7-rc3:

- Fix a lane bonding issue on ASMedia USB4 device
- Send uevents when link is switched to asymmetric or symmetric
- Only add device router DP IN adapters to the head of resource list
to avoid issues during system resume.

All these have been in linux-next with no reported issues.

* tag 'thunderbolt-for-v6.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt: (1451 commits)
thunderbolt: Only add device router DP IN to the head of the DP resource list
thunderbolt: Send uevent after asymmetric/symmetric switch
thunderbolt: Set lane bonding bit only for downstream port

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porting: document block device freeze and thaw changes

Link: https://lore.kernel.org/r/20230927-vfs-super-freeze-v1-7-ecc36d9ab4d9@kernel.org
Link: https://lore.kernel.org/r/20231024-vfs-super-freez

porting: document block device freeze and thaw changes

Link: https://lore.kernel.org/r/20230927-vfs-super-freeze-v1-7-ecc36d9ab4d9@kernel.org
Link: https://lore.kernel.org/r/20231024-vfs-super-freeze-v2-9-599c19f4faac@kernel.org
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

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Merge drm/drm-next into drm-misc-next

Let's kickstart the v6.8 release cycle.

Signed-off-by: Maxime Ripard <mripard@kernel.org>

Merge branch 'tip/perf/urgent'

Avoid conflicts, base on fixes.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>

Merge tag 'vfs-6.7.fsid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fanotify fsid updates from Christian Brauner:
"This work is part of the plan to enable fanotify to serve a

Merge tag 'vfs-6.7.fsid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fanotify fsid updates from Christian Brauner:
"This work is part of the plan to enable fanotify to serve as a drop-in
replacement for inotify. While inotify is availabe on all filesystems,
fanotify currently isn't.

In order to support fanotify on all filesystems two things are needed:

(1) all filesystems need to support AT_HANDLE_FID

(2) all filesystems need to report a non-zero f_fsid

This contains (1) and allows filesystems to encode non-decodable file
handlers for fanotify without implementing any exportfs operations by
encoding a file id of type FILEID_INO64_GEN from i_ino and
i_generation.

Filesystems that want to opt out of encoding non-decodable file ids
for fanotify that don't support NFS export can do so by providing an
empty export_operations struct.

This also partially addresses (2) by generating f_fsid for simple
filesystems as well as freevxfs. Remaining filesystems will be dealt
with by separate patches.

Finally, this contains the patch from the current exportfs maintainers
which moves exportfs under vfs with Chuck, Jeff, and Amir as
maintainers and vfs.git as tree"

* tag 'vfs-6.7.fsid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
MAINTAINERS: create an entry for exportfs
fs: fix build error with CONFIG_EXPORTFS=m or not defined
freevxfs: derive f_fsid from bdev->bd_dev
fs: report f_fsid from s_dev for "simple" filesystems
exportfs: support encoding non-decodeable file handles by default
exportfs: define FILEID_INO64_GEN* file handle types
exportfs: make ->encode_fh() a mandatory method for NFS export
exportfs: add helpers to check if filesystem can encode/decode file handles

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Merge branch 'next' into for-linus

Prepare input updates for 6.7 merge window.