linux.git/fs/kernfs, branch v5.9

fsnotify: pass dir and inode arguments to fsnotify()

2020-07-27T21:15:48+00:00

The arguments of fsnotify() are overloaded and mean different things
for different event types.

Replace the to_tell argument with separate arguments @dir and @inode,
because we may be sending to both dir and child.  Using the @data
argument to pass the child is not enough, because dirent events pass
this argument (for audit), but we do not report to child.

Document the new fsnotify() function argumenets.

Link: https://lore.kernel.org/r/20200722125849.17418-7-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: create helper fsnotify_inode()

2020-07-27T21:13:51+00:00

Simple helper to consolidate biolerplate code.

Link: https://lore.kernel.org/r/20200722125849.17418-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: send event to parent and child with single callback

2020-07-27T19:24:52+00:00

Instead of calling fsnotify() twice, once with parent inode and once
with child inode, if event should be sent to parent inode, send it
with both parent and child inodes marks in object type iterator and call
the backend handle_event() callback only once.

The parent inode is assigned to the standard "inode" iterator type and
the child inode is assigned to the special "child" iterator type.

In that case, the bit FS_EVENT_ON_CHILD will be set in the event mask,
the dir argument to handle_event will be the parent inode, the file_name
argument to handle_event is non NULL and refers to the name of the child
and the child inode can be accessed with fsnotify_data_inode().

This will allow fanotify to make decisions based on child or parent's
ignored mask.  For example, when a parent is interested in a specific
event on its children, but a specific child wishes to ignore this event,
the event will not be reported.  This is not what happens with current
code, but according to man page, it is the expected behavior.

Link: https://lore.kernel.org/r/20200716084230.30611-15-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

kernfs: do not call fsnotify() with name without a parent

2020-07-15T15:36:52+00:00

When creating an FS_MODIFY event on inode itself (not on parent)
the file_name argument should be NULL.

The change to send a non NULL name to inode itself was done on purpuse
as part of another commit, as Tejun writes: "...While at it, supply the
target file name to fsnotify() from kernfs_node->name.".

But this is wrong practice and inconsistent with inotify behavior when
watching a single file.  When a child is being watched (as opposed to the
parent directory) the inotify event should contain the watch descriptor,
but not the file name.

Fixes: df6a58c5c5aa ("kernfs: don't depend on d_find_any_alias()...")
Link: https://lore.kernel.org/r/20200708111156.24659-5-amir73il@gmail.com
Acked-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

mmap locking API: convert mmap_sem comments

2020-06-09T16:39:14+00:00

Convert comments that reference mmap_sem to reference mmap_lock instead.

[akpm@linux-foundation.org: fix up linux-next leftovers]
[akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil]
[akpm@linux-foundation.org: more linux-next fixups, per Michel]

Signed-off-by: Michel Lespinasse 
Signed-off-by: Andrew Morton 
Reviewed-by: Vlastimil Babka 
Reviewed-by: Daniel Jordan 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Hugh Dickins 
Cc: Jason Gunthorpe 
Cc: Jerome Glisse 
Cc: John Hubbard 
Cc: Laurent Dufour 
Cc: Liam Howlett 
Cc: Matthew Wilcox 
Cc: Peter Zijlstra 
Cc: Ying Han 
Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com
Signed-off-by: Linus Torvalds

kernfs: Change kernfs_node lockdep name to "kn->active"

2020-04-23T14:59:15+00:00

The kernfs_node lockdep tracking is being done on kn->active, the
active reference count. The other reference count (kn->count) is not
tracked by lockdep. So change the lockdep name to reflect what it is
tracking.

Signed-off-by: Waiman Long 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20200402171056.27871-1-longman@redhat.com
Signed-off-by: Greg Kroah-Hartman

kernfs: Add option to enable user xattrs

2020-03-16T19:53:47+00:00

User extended attributes are useful as metadata storage for kernfs
consumers like cgroups. Especially in the case of cgroups, it is useful
to have a central metadata store that multiple processes/services can
use to coordinate actions.

A concrete example is for userspace out of memory killers. We want to
let delegated cgroup subtree owners (running as non-root) to be able to
say "please avoid killing this cgroup". This is especially important for
desktop linux as delegated subtrees owners are less likely to run as
root.

This patch introduces a new flag, KERNFS_ROOT_SUPPORT_USER_XATTR, that
lets kernfs consumers enable user xattr support. An initial limit of 128
entries or 128KB -- whichever is hit first -- is placed per cgroup
because xattrs come from kernel memory and we don't want to let
unprivileged users accidentally eat up too much kernel memory.

Signed-off-by: Daniel Xu 
Acked-by: Chris Down 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Tejun Heo

kernfs: Add removed_size out param for simple_xattr_set

2020-03-16T19:53:47+00:00

This helps set up size accounting in the next commit. Without this out
param, it's difficult to find out the removed xattr size without taking
a lock for longer and walking the xattr linked list twice.

Signed-off-by: Daniel Xu 
Acked-by: Chris Down 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Tejun Heo

Merge branch 'imm.timestamp' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2020-02-05T05:02:42+00:00

Pull vfs timestamp updates from Al Viro:
 "More 64bit timestamp work"

* 'imm.timestamp' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  kernfs: don't bother with timestamp truncation
  fs: Do not overload update_time
  fs: Delete timespec64_trunc()
  fs: ubifs: Eliminate timespec64_trunc() usage
  fs: ceph: Delete timespec64_trunc() usage
  fs: cifs: Delete usage of timespec64_trunc
  fs: fat: Eliminate timespec64_trunc() usage
  utimes: Clamp the timestamps in notify_change()

fs/kernfs/dir.c: Clean code by removing always true condition

2020-01-14T15:14:47+00:00

Previously there was an additional check if variable pos is not null.
However, this check happens after entering while loop and only then,
which can happen only if pos is not null.
Therefore the additional check is redundant and can be removed.

Signed-off-by: Mateusz Nosek 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20191230191628.21099-1-mateusznosek0@gmail.com
Signed-off-by: Greg Kroah-Hartman