1. 18 Oct, 2016 1 commit
  2. 28 Sep, 2016 1 commit
  3. 22 Sep, 2016 3 commits
    • Peter Zijlstra's avatar
      fs/locks: Use percpu_down_read_preempt_disable() · 87709e28
      Peter Zijlstra authored
      Avoid spurious preemption.
      Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: dave@stgolabs.net
      Cc: der.herr@hofr.at
      Cc: paulmck@linux.vnet.ibm.com
      Cc: riel@redhat.com
      Cc: tj@kernel.org
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      87709e28
    • Peter Zijlstra's avatar
      fs/locks: Replace lg_local with a per-cpu spinlock · 7c3f654d
      Peter Zijlstra authored
      As Oleg suggested, replace file_lock_list with a structure containing
      the hlist head and a spinlock.
      
      This completely removes the lglock from fs/locks.
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: dave@stgolabs.net
      Cc: der.herr@hofr.at
      Cc: paulmck@linux.vnet.ibm.com
      Cc: riel@redhat.com
      Cc: tj@kernel.org
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      7c3f654d
    • Peter Zijlstra's avatar
      fs/locks: Replace lg_global with a percpu-rwsem · aba37660
      Peter Zijlstra authored
      Replace the global part of the lglock with a percpu-rwsem.
      
      Since fcl_lock is a spinlock and itself nests under i_lock, which too
      is a spinlock we cannot acquire sleeping locks at
      locks_{insert,remove}_global_locks().
      
      We can however wrap all fcl_lock acquisitions with percpu_down_read
      such that all invocations of locks_{insert,remove}_global_locks() have
      that read lock held.
      
      This allows us to replace the lg_global part of the lglock with the
      write side of the rwsem.
      
      In the absense of writers, percpu_{down,up}_read() are free of atomic
      instructions. This further avoids the very long preempt-disable
      regions caused by lglock on larger machines.
      Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: dave@stgolabs.net
      Cc: der.herr@hofr.at
      Cc: paulmck@linux.vnet.ibm.com
      Cc: riel@redhat.com
      Cc: tj@kernel.org
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      aba37660
  4. 16 Sep, 2016 2 commits
    • Miklos Szeredi's avatar
      vfs: do get_write_access() on upper layer of overlayfs · 4d0c5ba2
      Miklos Szeredi authored
      The problem with writecount is: we want consistent handling of it for
      underlying filesystems as well as overlayfs.  Making sure i_writecount is
      correct on all layers is difficult.  Instead this patch makes sure that
      when write access is acquired, it's always done on the underlying writable
      layer (called the upper layer).  We must also make sure to look at the
      writecount on this layer when checking for conflicting leases.
      
      Open for write already updates the upper layer's writecount.  Leaving only
      truncate.
      
      For truncate copy up must happen before get_write_access() so that the
      writecount is updated on the upper layer.  Problem with this is if
      something fails after that, then copy-up was done needlessly.  E.g. if
      break_lease() was interrupted.  Probably not a big deal in practice.
      
      Another interesting case is if there's a denywrite on a lower file that is
      then opened for write or truncated.  With this patch these will succeed,
      which is somewhat counterintuitive.  But I think it's still acceptable,
      considering that the copy-up does actually create a different file, so the
      old, denywrite mapping won't be touched.
      
      On non-overlayfs d_real() is an identity function and d_real_inode() is
      equivalent to d_inode() so this patch doesn't change behavior in that case.
      Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      Acked-by: default avatarJeff Layton <jlayton@poochiereds.net>
      Cc: "J. Bruce Fields" <bfields@fieldses.org>
      4d0c5ba2
    • Miklos Szeredi's avatar
      locks: fix file locking on overlayfs · c568d683
      Miklos Szeredi authored
      This patch allows flock, posix locks, ofd locks and leases to work
      correctly on overlayfs.
      
      Instead of using the underlying inode for storing lock context use the
      overlay inode.  This allows locks to be persistent across copy-up.
      
      This is done by introducing locks_inode() helper and using it instead of
      file_inode() to get the inode in locking code.  For non-overlayfs the two
      are equivalent, except for an extra pointer dereference in locks_inode().
      
      Since lock operations are in "struct file_operations" we must also make
      sure not to call underlying filesystem's lock operations.  Introcude a
      super block flag MS_NOREMOTELOCK to this effect.
      Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      Acked-by: default avatarJeff Layton <jlayton@poochiereds.net>
      Cc: "J. Bruce Fields" <bfields@fieldses.org>
      c568d683
  5. 18 Aug, 2016 1 commit
  6. 01 Jul, 2016 1 commit
    • Miklos Szeredi's avatar
      locks: use file_inode() · 6343a212
      Miklos Szeredi authored
      (Another one for the f_path debacle.)
      
      ltp fcntl33 testcase caused an Oops in selinux_file_send_sigiotask.
      
      The reason is that generic_add_lease() used filp->f_path.dentry->inode
      while all the others use file_inode().  This makes a difference for files
      opened on overlayfs since the former will point to the overlay inode the
      latter to the underlying inode.
      
      So generic_add_lease() added the lease to the overlay inode and
      generic_delete_lease() removed it from the underlying inode.  When the file
      was released the lease remained on the overlay inode's lock list, resulting
      in use after free.
      Reported-by: default avatarEryu Guan <eguan@redhat.com>
      Fixes: 4bacc9c9 ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      Reviewed-by: default avatarJeff Layton <jlayton@redhat.com>
      Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
      6343a212
  7. 22 Jan, 2016 1 commit
    • Al Viro's avatar
      wrappers for ->i_mutex access · 5955102c
      Al Viro authored
      parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
      inode_foo(inode) being mutex_foo(&inode->i_mutex).
      
      Please, use those for access to ->i_mutex; over the coming cycle
      ->i_mutex will become rwsem, with ->lookup() done with it held
      only shared.
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      5955102c
  8. 08 Jan, 2016 6 commits
  9. 18 Dec, 2015 1 commit
    • Paul Gortmaker's avatar
      fs: make locks.c explicitly non-modular · 91899226
      Paul Gortmaker authored
      The Kconfig currently controlling compilation of this code is:
      
      config FILE_LOCKING
           bool "Enable POSIX file locking API" if EXPERT
      
      ...meaning that it currently is not being built as a module by anyone.
      
      Lets remove the couple traces of modularity so that when reading the
      driver there is no doubt it is builtin-only.
      
      Since module_init translates to device_initcall in the non-modular
      case, the init ordering gets bumped to one level earlier when we
      use the more appropriate fs_initcall here.  However we've made similar
      changes before without any fallout and none is expected here either.
      
      Cc: Jeff Layton <jlayton@poochiereds.net>
      Acked-by: default avatarJeff Layton <jlayton@poochiereds.net>
      Cc: "J. Bruce Fields" <bfields@fieldses.org>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Cc: linux-fsdevel@vger.kernel.org
      Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
      Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
      91899226
  10. 08 Dec, 2015 1 commit
  11. 18 Nov, 2015 1 commit
  12. 16 Nov, 2015 1 commit
    • Jeff Layton's avatar
      locks: Allow disabling mandatory locking at compile time · 9e8925b6
      Jeff Layton authored
      Mandatory locking appears to be almost unused and buggy and there
      appears no real interest in doing anything with it.  Since effectively
      no one uses the code and since the code is buggy let's allow it to be
      disabled at compile time.  I would just suggest removing the code but
      undoubtedly that will break some piece of userspace code somewhere.
      
      For the distributions that don't care about this piece of code
      this gives a nice starting point to make mandatory locking go away.
      
      Cc: Benjamin Coddington <bcodding@redhat.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Jeff Layton <jeff.layton@primarydata.com>
      Cc: J. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
      Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
      9e8925b6
  13. 22 Oct, 2015 3 commits
  14. 15 Oct, 2015 1 commit
  15. 21 Sep, 2015 1 commit
    • Dmitry Vyukov's avatar
      fs: fix data races on inode->i_flctx · 128a3785
      Dmitry Vyukov authored
      locks_get_lock_context() uses cmpxchg() to install i_flctx.
      cmpxchg() is a release operation which is correct. But it uses
      a plain load to load i_flctx. This is incorrect. Subsequent loads
      from i_flctx can hoist above the load of i_flctx pointer itself
      and observe uninitialized garbage there. This in turn can lead
      to corruption of ctx->flc_lock and other members.
      
      Documentation/memory-barriers.txt explicitly requires to use
      a barrier in such context:
      "A load-load control dependency requires a full read memory barrier".
      
      Use smp_load_acquire() in locks_get_lock_context() and in bunch
      of other functions that can proceed concurrently with
      locks_get_lock_context().
      
      The data race was found with KernelThreadSanitizer (KTSAN).
      Signed-off-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
      128a3785
  16. 31 Aug, 2015 1 commit
  17. 13 Jul, 2015 3 commits
  18. 17 Apr, 2015 1 commit
    • Andrey Vagin's avatar
      proc: show locks in /proc/pid/fdinfo/X · 6c8c9031
      Andrey Vagin authored
      Let's show locks which are associated with a file descriptor in
      its fdinfo file.
      
      Currently we don't have a reliable way to determine who holds a lock.  We
      can find some information in /proc/locks, but PID which is reported there
      can be wrong.  For example, a process takes a lock, then forks a child and
      dies.  In this case /proc/locks contains the parent pid, which can be
      reused by another process.
      
      $ cat /proc/locks
      ...
      6: FLOCK  ADVISORY  WRITE 324 00:13:13431 0 EOF
      ...
      
      $ ps -C rpcbind
        PID TTY          TIME CMD
        332 ?        00:00:00 rpcbind
      
      $ cat /proc/332/fdinfo/4
      pos:	0
      flags:	0100000
      mnt_id:	22
      lock:	1: FLOCK  ADVISORY  WRITE 324 00:13:13431 0 EOF
      
      $ ls -l /proc/332/fd/4
      lr-x------ 1 root root 64 Mar  5 14:43 /proc/332/fd/4 -> /run/rpcbind.lock
      
      $ ls -l /proc/324/fd/
      total 0
      lrwx------ 1 root root 64 Feb 27 14:50 0 -> /dev/pts/0
      lrwx------ 1 root root 64 Feb 27 14:50 1 -> /dev/pts/0
      lrwx------ 1 root root 64 Feb 27 14:49 2 -> /dev/pts/0
      
      You can see that the process with the 324 pid doesn't hold the lock.
      
      This information is required for proper dumping and restoring file
      locks.
      Signed-off-by: default avatarAndrey Vagin <avagin@openvz.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Acked-by: default avatarJeff Layton <jlayton@poochiereds.net>
      Acked-by: default avatar"J. Bruce Fields" <bfields@fieldses.org>
      Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Joe Perches <joe@perches.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6c8c9031
  19. 03 Apr, 2015 7 commits
  20. 27 Mar, 2015 1 commit
  21. 14 Mar, 2015 1 commit
  22. 04 Mar, 2015 1 commit
    • Jeff Layton's avatar
      locks: fix fasync_struct memory leak in lease upgrade/downgrade handling · 0164bf02
      Jeff Layton authored
      Commit 8634b51f (locks: convert lease handling to file_lock_context)
      introduced a regression in the handling of lease upgrade/downgrades.
      
      In the event that we already have a lease on a file and are going to
      either upgrade or downgrade it, we skip doing any list insertion or
      deletion and simply re-call lm_setup on the existing lease.
      
      As of commit 8634b51f however, we end up calling lm_setup on the
      lease that was passed in, instead of on the existing lease. This causes
      us to leak the fasync_struct that was allocated in the event that there
      was not already an existing one (as it always appeared that there
      wasn't one).
      
      Fixes: 8634b51f (locks: convert lease handling to file_lock_context)
      Reported-and-Tested-by: default avatarDaniel Wagner <daniel.wagner@bmw-carit.de>
      Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
      0164bf02