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  1. Apr 26, 2024
  3. Nov 14, 2023
  5. Oct 18, 2023
  7. Aug 20, 2022
  9. Sep 19, 2021
  11. Jan 15, 2021
  13. Jan 14, 2021
    • Daniel Colascione's avatar
      fs: add LSM-supporting anon-inode interface · e7e832ce
      Daniel Colascione authored 
      
This change adds a new function, anon_inode_getfd_secure, that creates
anonymous-node file with individual non-S_PRIVATE inode to which security
modules can apply policy. Existing callers continue using the original
singleton-inode kind of anonymous-inode file. We can transition anonymous
inode users to the new kind of anonymous inode in individual patches for
the sake of bisection and review.

The new function accepts an optional context_inode parameter that callers
can use to provide additional contextual information to security modules.
For example, in case of userfaultfd, the created inode is a 'logical child'
of the context_inode (userfaultfd inode of the parent process) in the sense
that it provides the security context required during creation of the child
process' userfaultfd inode.

Signed-off-by: default avatarDaniel Colascione <dancol@google.com>
[LG: Delete obsolete comments to alloc_anon_inode()]
[LG: Add context_inode description in comments to anon_inode_getfd_secure()]
[LG: Remove definition of anon_inode_getfile_secure() as there are no callers]
[LG: Make __anon_inode_getfile() static]
[LG: Use correct error cast in __anon_inode_getfile()]
[LG: Fix error handling in __anon_inode_getfile()]
Signed-off-by: default avatarLokesh Gidra <lokeshgidra@google.com>
Reviewed-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
      e7e832ce
  15. May 25, 2019
    • David Howells's avatar
      vfs: Convert anon_inodes to use the new mount API · 33cada40
      David Howells authored 
      
Convert the anon_inodes filesystem to the new internal mount API as the old
one will be obsoleted and removed.  This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.

See Documentation/filesystems/mount_api.txt for more information.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      33cada40
    • Al Viro's avatar
      mount_pseudo(): drop 'name' argument, switch to d_make_root() · 1f58bb18
      Al Viro authored 
      
Once upon a time we used to set ->d_name of e.g. pipefs root
so that d_path() on pipes would work.  These days it's
completely pointless - dentries of pipes are not even connected
to pipefs root.  However, mount_pseudo() had set the root
dentry name (passed as the second argument) and callers
kept inventing names to pass to it.  Including those that
didn't *have* any non-root dentries to start with...

All of that had been pointless for about 8 years now; it's
time to get rid of that cargo-culting...

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      1f58bb18
  17. May 21, 2019
  19. Jul 12, 2018
  21. Dec 24, 2016
  23. Mar 27, 2014
  25. Mar 25, 2014
  27. Nov 09, 2013
  29. Jul 16, 2013
  31. Feb 26, 2013
  33. Feb 22, 2013
    • Anatol Pomozov's avatar
      fs: Preserve error code in get_empty_filp(), part 2 · 39b65252
      Anatol Pomozov authored 
      
Allocating a file structure in function get_empty_filp() might fail because
of several reasons:
 - not enough memory for file structures
 - operation is not allowed
 - user is over its limit

Currently the function returns NULL in all cases and we loose the exact
reason of the error. All callers of get_empty_filp() assume that the function
can fail with ENFILE only.

Return error through pointer. Change all callers to preserve this error code.

[AV: cleaned up a bit, carved the get_empty_filp() part out into a separate commit
(things remaining here deal with alloc_file()), removed pipe(2) behaviour change]

Signed-off-by: default avatarAnatol Pomozov <anatol.pomozov@gmail.com>
Reviewed-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      39b65252
  35. Mar 20, 2012
  37. Jul 26, 2011
  39. Jul 24, 2011
    • Tim Chen's avatar
      VFS : mount lock scalability for internal mounts · 423e0ab0
      Tim Chen authored 
      
For a number of file systems that don't have a mount point (e.g. sockfs
and pipefs), they are not marked as long term. Therefore in
mntput_no_expire, all locks in vfs_mount lock are taken instead of just
local cpu's lock to aggregate reference counts when we release
reference to file objects.  In fact, only local lock need to have been
taken to update ref counts as these file systems are in no danger of
going away until we are ready to unregister them.

The attached patch marks file systems using kern_mount without
mount point as long term.  The contentions of vfs_mount lock
is now eliminated.  Before un-registering such file system,
kern_unmount should be called to remove the long term flag and
make the mount point ready to be freed.

Signed-off-by: default avatarTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      423e0ab0
  41. Jan 16, 2011
    • Al Viro's avatar
      sanitize vfsmount refcounting changes · f03c6599
      Al Viro authored 
      Instead of splitting refcount between (per-cpu) mnt_count
and (SMP-only) mnt_longrefs, make all references contribute
to mnt_count again and keep track of how many are longterm
ones.

Accounting rules for longterm count:
	* 1 for each fs_struct.root.mnt
	* 1 for each fs_struct.pwd.mnt
	* 1 for having non-NULL ->mnt_ns
	* decrement to 0 happens only under vfsmount lock exclusive

That allows nice common case for mntput() - since we can't drop the
final reference until after mnt_longterm has reached 0 due to the rules
above, mntput() can grab vfsmount lock shared and check mnt_longterm.
If it turns out to be non-zero (which is the common case), we know
that this is not the final mntput() and can just blindly decrement
percpu mnt_count.  Otherwise we grab vfsmount lock exclusive and
do usual decrement-and-check of percpu mnt_count.

For fs_struct.c we have mnt_make_longterm() and mnt_make_shortterm();
namespace.c uses the latter in places where we don't already hold
vfsm...
      f03c6599
  43. Jan 12, 2011
  45. Jan 07, 2011
    • Nicholas Piggin's avatar
      fs: scale mntget/mntput · b3e19d92
      Nicholas Piggin authored 
      The problem that this patch aims to fix is vfsmount refcounting scalability.
We need to take a reference on the vfsmount for every successful path lookup,
which often go to the same mount point.

The fundamental difficulty is that a "simple" reference count can never be made
scalable, because any time a reference is dropped, we must check whether that
was the last reference. To do that requires communication with all other CPUs
that may have taken a reference count.

We can make refcounts more scalable in a couple of ways, involving keeping
distributed counters, and checking for the global-zero condition less
frequently.

- check the global sum once every interval (this will delay zero detection
  for some interval, so it's probably a showstopper for vfsmounts).

- keep a local count and only taking the global sum when local reaches 0 (this
  is difficult for vfsmounts, because we can't hold preempt off for the life of
  a reference, so a counter would need to be per-thread or tied...
      b3e19d92
    • Nicholas Piggin's avatar
      fs: improve scalability of pseudo filesystems · 4b936885
      Nicholas Piggin authored 
      
Regardless of how much we possibly try to scale dcache, there is likely
always going to be some fundamental contention when adding or removing children
under the same parent. Pseudo filesystems do not seem need to have connected
dentries because by definition they are disconnected.

Signed-off-by: default avatarNick Piggin <npiggin@kernel.dk>
      4b936885
    • Nicholas Piggin's avatar
      fs: dcache reduce branches in lookup path · fb045adb
      Nicholas Piggin authored 
      
Reduce some branches and memory accesses in dcache lookup by adding dentry
flags to indicate common d_ops are set, rather than having to check them.
This saves a pointer memory access (dentry->d_op) in common path lookup
situations, and saves another pointer load and branch in cases where we
have d_op but not the particular operation.

Patched with:

git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i

Signed-off-by: default avatarNick Piggin <npiggin@kernel.dk>
      fb045adb
  47. Dec 10, 2010
  49. Oct 29, 2010
  51. Oct 25, 2010
  53. May 27, 2010
  55. May 21, 2010
  57. Mar 30, 2010
    • Tejun Heo's avatar
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      Tejun Heo authored 
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  bloc...
      5a0e3ad6
  59. Mar 12, 2010
    • Eric Paris's avatar
      anon_inodes: mark the anon inode private · 3836a03d
      Eric Paris authored 
      Inotify was switched to use anon_inode instead of its own private filesystem
which only had one inode in commit c44dcc56

 "switch inotify_user to
anon_inode"

The problem with this is that now the inotify inode is not a distinct inode
which can be managed by LSMs.  userspace tools which use inotify were allowed
to use the inotify inode but may not have had permission to do read/write type
operations on the anon_inode.  After looking at the anon_inode and its users
it looks like the best solution is to just mark the anon_inode as S_PRIVATE
so the security system will ignore it.

Signed-off-by: default avatarEric Paris <eparis@redhat.com>
Acked-by: default avatarJames Morris <jmorris@namei.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3836a03d
  61. Dec 22, 2009

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