1. 29 9月, 2014 1 次提交
  2. 09 9月, 2014 2 次提交
    • B
      xfs: add debug sysfs attribute set · 65b65735
      Brian Foster 提交于
      Create a top-level debug directory for global debug sysfs attributes.
      This directory is added and removed on XFS module initialization and
      removal respectively for DEBUG mode kernels only. It typically resides
      at /sys/fs/xfs/debug. It is located at the top level of the xfs sysfs
      hierarchy as attributes might define global behavior or behavior that
      must be configured before an xfs mount is available (e.g., log recovery
      behavior).
      
      Define the global debug kobject that represents the debug sysfs
      directory and add generic attribute show/store helpers to support future
      attributes. No debug attributes are exported as of yet.
      Signed-off-by: NBrian Foster <bfoster@redhat.com>
      Reviewed-by: NDave Chinner <dchinner@redhat.com>
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      65b65735
    • B
      xfs: mark all internal workqueues as freezable · 8018ec08
      Brian Foster 提交于
      Workqueues must be explicitly set as freezable to ensure they are frozen
      in the assocated part of the hibernation/suspend sequence. Freezing of
      workqueues and kernel threads is important to ensure that modifications
      are not made on-disk after the hibernation image has been created.
      Otherwise, the in-memory state can become inconsistent with what is on
      disk and eventually lead to filesystem corruption. We have reports of
      free space btree corruptions that occur immediately after restore from
      hibernate that suggest the xfs-eofblocks workqueue could be causing
      such problems if it races with hibernation.
      
      Mark all of the internal XFS workqueues as freezable to ensure nothing
      changes on-disk once the freezer infrastructure freezes kernel threads
      and creates the hibernation image.
      Signed-off-by: NBrian Foster <bfoster@redhat.com>
      Reported-by: NCarlos E. R. <carlos.e.r@opensuse.org>
      Reviewed-by: NDave Chinner <dchinner@redhat.com>
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      8018ec08
  3. 30 7月, 2014 1 次提交
  4. 24 7月, 2014 2 次提交
    • E
      xfs: tidy up xfs_set_inode32 · 54aa61f8
      Eric Sandeen 提交于
      xfs_set_inode32() caught my eye because it had weird spacing around
      the "-1's".  In cleaning that up, I realized that the assignment in
      the declaration of "ino" is never used; it's rewritten before it
      gets read.
      
      Drop the ino initializer from its declaration since it's not used,
      and move the agino initialization into the body of the function,
      mostly so that we can have pretty whitespace and not exceed 80
      columns.  :)
      Signed-off-by: NEric Sandeen <sandeen@redhat.com>
      Reviewed-by: NBrian Foster <bfoster@redhat.com>
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      54aa61f8
    • E
      xfs: allow inode allocations in post-growfs disk space · 9de67c3b
      Eric Sandeen 提交于
      Today, if we perform an xfs_growfs which adds allocation groups,
      mp->m_maxagi is not properly updated when the growfs is complete.
      
      Therefore inodes will continue to be allocated only in the
      AGs which existed prior to the growfs, and the new space
      won't be utilized.
      
      This is because of this path in xfs_growfs_data_private():
      
      xfs_growfs_data_private
      	xfs_initialize_perag(mp, nagcount, &nagimax);
      		if (mp->m_flags & XFS_MOUNT_32BITINODES)
      			index = xfs_set_inode32(mp);
      		else
      			index = xfs_set_inode64(mp);
      
      		if (maxagi)
      			*maxagi = index;
      
      where xfs_set_inode* iterates over the (old) agcount in
      mp->m_sb.sb_agblocks, which has not yet been updated
      in the growfs path.  So "index" will be returned based on
      the old agcount, not the new one, and new AGs are not available
      for inode allocation.
      
      Fix this by explicitly passing the proper AG count (which
      xfs_initialize_perag() already has) down another level,
      so that xfs_set_inode* can make the proper decision about
      acceptable AGs for inode allocation in the potentially
      newly-added AGs.
      
      This has been broken since 3.7, when these two
      xfs_set_inode* functions were added in commit 2d2194f6.
      Prior to that, we looped over "agcount" not sb_agblocks
      in these calculations.
      Signed-off-by: NEric Sandeen <sandeen@redhat.com>
      Reviewed-by: NBrian Foster <bfoster@redhat.com>
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      9de67c3b
  5. 15 7月, 2014 1 次提交
  6. 25 6月, 2014 1 次提交
    • D
      xfs: global error sign conversion · 2451337d
      Dave Chinner 提交于
      Convert all the errors the core XFs code to negative error signs
      like the rest of the kernel and remove all the sign conversion we
      do in the interface layers.
      
      Errors for conversion (and comparison) found via searches like:
      
      $ git grep " E" fs/xfs
      $ git grep "return E" fs/xfs
      $ git grep " E[A-Z].*;$" fs/xfs
      
      Negation points found via searches like:
      
      $ git grep "= -[a-z,A-Z]" fs/xfs
      $ git grep "return -[a-z,A-D,F-Z]" fs/xfs
      $ git grep " -[a-z].*;" fs/xfs
      
      [ with some bits I missed from Brian Foster ]
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Reviewed-by: NBrian Foster <bfoster@redhat.com>
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      2451337d
  7. 22 6月, 2014 1 次提交
  8. 15 5月, 2014 2 次提交
  9. 23 4月, 2014 1 次提交
  10. 14 4月, 2014 2 次提交
  11. 04 4月, 2014 1 次提交
    • J
      mm + fs: store shadow entries in page cache · 91b0abe3
      Johannes Weiner 提交于
      Reclaim will be leaving shadow entries in the page cache radix tree upon
      evicting the real page.  As those pages are found from the LRU, an
      iput() can lead to the inode being freed concurrently.  At this point,
      reclaim must no longer install shadow pages because the inode freeing
      code needs to ensure the page tree is really empty.
      
      Add an address_space flag, AS_EXITING, that the inode freeing code sets
      under the tree lock before doing the final truncate.  Reclaim will check
      for this flag before installing shadow pages.
      Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Reviewed-by: NMinchan Kim <minchan@kernel.org>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Bob Liu <bob.liu@oracle.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Luigi Semenzato <semenzato@google.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Metin Doslu <metin@citusdata.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Ozgun Erdogan <ozgun@citusdata.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Roman Gushchin <klamm@yandex-team.ru>
      Cc: Ryan Mallon <rmallon@gmail.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      91b0abe3
  12. 13 3月, 2014 1 次提交
    • T
      fs: push sync_filesystem() down to the file system's remount_fs() · 02b9984d
      Theodore Ts'o 提交于
      Previously, the no-op "mount -o mount /dev/xxx" operation when the
      file system is already mounted read-write causes an implied,
      unconditional syncfs().  This seems pretty stupid, and it's certainly
      documented or guaraunteed to do this, nor is it particularly useful,
      except in the case where the file system was mounted rw and is getting
      remounted read-only.
      
      However, it's possible that there might be some file systems that are
      actually depending on this behavior.  In most file systems, it's
      probably fine to only call sync_filesystem() when transitioning from
      read-write to read-only, and there are some file systems where this is
      not needed at all (for example, for a pseudo-filesystem or something
      like romfs).
      Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
      Cc: linux-fsdevel@vger.kernel.org
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Artem Bityutskiy <dedekind1@gmail.com>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Evgeniy Dushistov <dushistov@mail.ru>
      Cc: Jan Kara <jack@suse.cz>
      Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
      Cc: Anders Larsen <al@alarsen.net>
      Cc: Phillip Lougher <phillip@squashfs.org.uk>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
      Cc: Petr Vandrovec <petr@vandrovec.name>
      Cc: xfs@oss.sgi.com
      Cc: linux-btrfs@vger.kernel.org
      Cc: linux-cifs@vger.kernel.org
      Cc: samba-technical@lists.samba.org
      Cc: codalist@coda.cs.cmu.edu
      Cc: linux-ext4@vger.kernel.org
      Cc: linux-f2fs-devel@lists.sourceforge.net
      Cc: fuse-devel@lists.sourceforge.net
      Cc: cluster-devel@redhat.com
      Cc: linux-mtd@lists.infradead.org
      Cc: jfs-discussion@lists.sourceforge.net
      Cc: linux-nfs@vger.kernel.org
      Cc: linux-nilfs@vger.kernel.org
      Cc: linux-ntfs-dev@lists.sourceforge.net
      Cc: ocfs2-devel@oss.oracle.com
      Cc: reiserfs-devel@vger.kernel.org
      02b9984d
  13. 22 2月, 2014 1 次提交
    • J
      Revert "writeback: do not sync data dirtied after sync start" · 0dc83bd3
      Jan Kara 提交于
      This reverts commit c4a391b5. Dave
      Chinner <david@fromorbit.com> has reported the commit may cause some
      inodes to be left out from sync(2). This is because we can call
      redirty_tail() for some inode (which sets i_dirtied_when to current time)
      after sync(2) has started or similarly requeue_inode() can set
      i_dirtied_when to current time if writeback had to skip some pages. The
      real problem is in the functions clobbering i_dirtied_when but fixing
      that isn't trivial so revert is a safer choice for now.
      
      CC: stable@vger.kernel.org # >= 3.13
      Signed-off-by: NJan Kara <jack@suse.cz>
      0dc83bd3
  14. 13 11月, 2013 1 次提交
    • J
      writeback: do not sync data dirtied after sync start · c4a391b5
      Jan Kara 提交于
      When there are processes heavily creating small files while sync(2) is
      running, it can easily happen that quite some new files are created
      between WB_SYNC_NONE and WB_SYNC_ALL pass of sync(2).  That can happen
      especially if there are several busy filesystems (remember that sync
      traverses filesystems sequentially and waits in WB_SYNC_ALL phase on one
      fs before starting it on another fs).  Because WB_SYNC_ALL pass is slow
      (e.g.  causes a transaction commit and cache flush for each inode in
      ext3), resulting sync(2) times are rather large.
      
      The following script reproduces the problem:
      
        function run_writers
        {
          for (( i = 0; i < 10; i++ )); do
            mkdir $1/dir$i
            for (( j = 0; j < 40000; j++ )); do
              dd if=/dev/zero of=$1/dir$i/$j bs=4k count=4 &>/dev/null
            done &
          done
        }
      
        for dir in "$@"; do
          run_writers $dir
        done
      
        sleep 40
        time sync
      
      Fix the problem by disregarding inodes dirtied after sync(2) was called
      in the WB_SYNC_ALL pass.  To allow for this, sync_inodes_sb() now takes
      a time stamp when sync has started which is used for setting up work for
      flusher threads.
      
      To give some numbers, when above script is run on two ext4 filesystems
      on simple SATA drive, the average sync time from 10 runs is 267.549
      seconds with standard deviation 104.799426.  With the patched kernel,
      the average sync time from 10 runs is 2.995 seconds with standard
      deviation 0.096.
      Signed-off-by: NJan Kara <jack@suse.cz>
      Reviewed-by: NFengguang Wu <fengguang.wu@intel.com>
      Reviewed-by: NDave Chinner <dchinner@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c4a391b5
  15. 31 10月, 2013 1 次提交
  16. 24 10月, 2013 4 次提交
    • D
      xfs: decouple inode and bmap btree header files · a4fbe6ab
      Dave Chinner 提交于
      Currently the xfs_inode.h header has a dependency on the definition
      of the BMAP btree records as the inode fork includes an array of
      xfs_bmbt_rec_host_t objects in it's definition.
      
      Move all the btree format definitions from xfs_btree.h,
      xfs_bmap_btree.h, xfs_alloc_btree.h and xfs_ialloc_btree.h to
      xfs_format.h to continue the process of centralising the on-disk
      format definitions. With this done, the xfs inode definitions are no
      longer dependent on btree header files.
      
      The enables a massive culling of unnecessary includes, with close to
      200 #include directives removed from the XFS kernel code base.
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Reviewed-by: NBen Myers <bpm@sgi.com>
      Signed-off-by: NBen Myers <bpm@sgi.com>
      a4fbe6ab
    • D
      xfs: decouple log and transaction headers · 239880ef
      Dave Chinner 提交于
      xfs_trans.h has a dependency on xfs_log.h for a couple of
      structures. Most code that does transactions doesn't need to know
      anything about the log, but this dependency means that they have to
      include xfs_log.h. Decouple the xfs_trans.h and xfs_log.h header
      files and clean up the includes to be in dependency order.
      
      In doing this, remove the direct include of xfs_trans_reserve.h from
      xfs_trans.h so that we remove the dependency between xfs_trans.h and
      xfs_mount.h. Hence the xfs_trans.h include can be moved to the
      indicate the actual dependencies other header files have on it.
      
      Note that these are kernel only header files, so this does not
      translate to any userspace changes at all.
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Reviewed-by: NBen Myers <bpm@sgi.com>
      Signed-off-by: NBen Myers <bpm@sgi.com>
      239880ef
    • D
      xfs: unify directory/attribute format definitions · 57062787
      Dave Chinner 提交于
      The on-disk format definitions for the directory and attribute
      structures are spread across 3 header files right now, only one of
      which is dedicated to defining on-disk structures and their
      manipulation (xfs_dir2_format.h). Pull all the format definitions
      into a single header file - xfs_da_format.h - and switch all the
      code over to point at that.
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Reviewed-by: NBen Myers <bpm@sgi.com>
      Signed-off-by: NBen Myers <bpm@sgi.com>
      57062787
    • D
      xfs: create a shared header file for format-related information · 70a9883c
      Dave Chinner 提交于
      All of the buffer operations structures are needed to be exported
      for xfs_db, so move them all to a common location rather than
      spreading them all over the place. They are verifying the on-disk
      format, so while xfs_format.h might be a good place, it is not part
      of the on disk format.
      
      Hence we need to create a new header file that we centralise these
      related definitions. Start by moving the bffer operations
      structures, and then also move all the other definitions that have
      crept into xfs_log_format.h and xfs_format.h as there was no other
      shared header file to put them in.
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Reviewed-by: NChristoph Hellwig <hch@lst.de>
      Signed-off-by: NBen Myers <bpm@sgi.com>
      70a9883c
  17. 18 10月, 2013 1 次提交
  18. 02 10月, 2013 1 次提交
  19. 11 9月, 2013 2 次提交
    • D
      fs: convert inode and dentry shrinking to be node aware · 9b17c623
      Dave Chinner 提交于
      Now that the shrinker is passing a node in the scan control structure, we
      can pass this to the the generic LRU list code to isolate reclaim to the
      lists on matching nodes.
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Signed-off-by: NGlauber Costa <glommer@parallels.com>
      Acked-by: NMel Gorman <mgorman@suse.de>
      Cc: "Theodore Ts'o" <tytso@mit.edu>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
      Cc: Arve Hjønnevåg <arve@android.com>
      Cc: Carlos Maiolino <cmaiolino@redhat.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Chuck Lever <chuck.lever@oracle.com>
      Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Gleb Natapov <gleb@redhat.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: J. Bruce Fields <bfields@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Jerome Glisse <jglisse@redhat.com>
      Cc: John Stultz <john.stultz@linaro.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Kent Overstreet <koverstreet@google.com>
      Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Marcelo Tosatti <mtosatti@redhat.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Steven Whitehouse <swhiteho@redhat.com>
      Cc: Thomas Hellstrom <thellstrom@vmware.com>
      Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      9b17c623
    • D
      shrinker: convert superblock shrinkers to new API · 0a234c6d
      Dave Chinner 提交于
      Convert superblock shrinker to use the new count/scan API, and propagate
      the API changes through to the filesystem callouts.  The filesystem
      callouts already use a count/scan API, so it's just changing counters to
      longs to match the VM API.
      
      This requires the dentry and inode shrinker callouts to be converted to
      the count/scan API.  This is mainly a mechanical change.
      
      [glommer@openvz.org: use mult_frac for fractional proportions, build fixes]
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Signed-off-by: NGlauber Costa <glommer@openvz.org>
      Acked-by: NMel Gorman <mgorman@suse.de>
      Cc: "Theodore Ts'o" <tytso@mit.edu>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
      Cc: Arve Hjønnevåg <arve@android.com>
      Cc: Carlos Maiolino <cmaiolino@redhat.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Chuck Lever <chuck.lever@oracle.com>
      Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Gleb Natapov <gleb@redhat.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: J. Bruce Fields <bfields@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Jerome Glisse <jglisse@redhat.com>
      Cc: John Stultz <john.stultz@linaro.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Kent Overstreet <koverstreet@google.com>
      Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Marcelo Tosatti <mtosatti@redhat.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Steven Whitehouse <swhiteho@redhat.com>
      Cc: Thomas Hellstrom <thellstrom@vmware.com>
      Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      0a234c6d
  20. 13 8月, 2013 4 次提交
  21. 31 7月, 2013 1 次提交
  22. 23 7月, 2013 1 次提交
  23. 29 6月, 2013 2 次提交
  24. 28 6月, 2013 1 次提交
    • D
      xfs: Inode create log items · 3ebe7d2d
      Dave Chinner 提交于
      Introduce the inode create log item type for logical inode create logging.
      Instead of logging the changes in buffers, pass the range to be
      initialised through the log by a new transaction type.  This reduces
      the amount of log space required to record initialisation during
      allocation from about 128 bytes per inode to a small fixed amount
      per inode extent to be initialised.
      
      This requires a new log item type to track it through the log
      and the AIL. This is a relatively simple item - most callbacks are
      noops as this item has the same life cycle as the transaction.
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      Reviewed-by: NMark Tinguely <tinguely@sgi.com>
      Signed-off-by: NBen Myers <bpm@sgi.com>
      3ebe7d2d
  25. 20 6月, 2013 1 次提交
    • J
      xfs: Remove XFS_MOUNT_RETERR · 39a45d84
      Jie Liu 提交于
      XFS_MOUNT_RETERR is going to be set at xfs_parseargs() if
      mp->m_dalign is enabled, so any time we enter "if (mp->m_dalign)"
      branch in xfs_update_alignment(), XFS_MOUNT_RETERR is set and so
      we always be emitting a warning and returning an error.
      
      Hence, we can remove it and get rid of a couple of redundant
      check up against it at xfs_upate_alignment().
      
      Thanks Dave Chinner for the suggestions of simplify the code
      in xfs_parseargs().
      Signed-off-by: NJie Liu <jeff.liu@oracle.com>
      Cc: Dave Chinner <dchinner@redhat.com>
      Cc: Mark Tinguely <tinguely@sgi.com>
      Reviewed-by: NMark Tinguely <tinguely@sgi.com>
      Signed-off-by: NBen Myers <bpm@sgi.com>
      39a45d84
  26. 06 6月, 2013 2 次提交
  27. 04 3月, 2013 1 次提交
    • E
      fs: Limit sys_mount to only request filesystem modules. · 7f78e035
      Eric W. Biederman 提交于
      Modify the request_module to prefix the file system type with "fs-"
      and add aliases to all of the filesystems that can be built as modules
      to match.
      
      A common practice is to build all of the kernel code and leave code
      that is not commonly needed as modules, with the result that many
      users are exposed to any bug anywhere in the kernel.
      
      Looking for filesystems with a fs- prefix limits the pool of possible
      modules that can be loaded by mount to just filesystems trivially
      making things safer with no real cost.
      
      Using aliases means user space can control the policy of which
      filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf
      with blacklist and alias directives.  Allowing simple, safe,
      well understood work-arounds to known problematic software.
      
      This also addresses a rare but unfortunate problem where the filesystem
      name is not the same as it's module name and module auto-loading
      would not work.  While writing this patch I saw a handful of such
      cases.  The most significant being autofs that lives in the module
      autofs4.
      
      This is relevant to user namespaces because we can reach the request
      module in get_fs_type() without having any special permissions, and
      people get uncomfortable when a user specified string (in this case
      the filesystem type) goes all of the way to request_module.
      
      After having looked at this issue I don't think there is any
      particular reason to perform any filtering or permission checks beyond
      making it clear in the module request that we want a filesystem
      module.  The common pattern in the kernel is to call request_module()
      without regards to the users permissions.  In general all a filesystem
      module does once loaded is call register_filesystem() and go to sleep.
      Which means there is not much attack surface exposed by loading a
      filesytem module unless the filesystem is mounted.  In a user
      namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT,
      which most filesystems do not set today.
      Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
      Acked-by: NKees Cook <keescook@chromium.org>
      Reported-by: NKees Cook <keescook@google.com>
      Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      7f78e035