1. 26 Sep, 2012 2 commits
    • Mikulas Patocka's avatar
      blockdev: turn a rw semaphore into a percpu rw semaphore · 62ac665f
      Mikulas Patocka authored
      
      
      This avoids cache line bouncing when many processes lock the semaphore
      for read.
      
      New percpu lock implementation
      
      The lock consists of an array of percpu unsigned integers, a boolean
      variable and a mutex.
      
      When we take the lock for read, we enter rcu read section, check for a
      "locked" variable. If it is false, we increase a percpu counter on the
      current cpu and exit the rcu section. If "locked" is true, we exit the
      rcu section, take the mutex and drop it (this waits until a writer
      finished) and retry.
      
      Unlocking for read just decreases percpu variable. Note that we can
      unlock on a difference cpu than where we locked, in this case the
      counter underflows. The sum of all percpu counters represents the number
      of processes that hold the lock for read.
      
      When we need to lock for write, we take the mutex, set "locked" variable
      to true and synchronize rcu. Since RCU has been synchronized, no
      processes can create new read locks. We wait until the sum of percpu
      counters is zero - when it is, there are no readers in the critical
      section.
      Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      62ac665f
    • Mikulas Patocka's avatar
      Fix a crash when block device is read and block size is changed at the same time · b87570f5
      Mikulas Patocka authored
      
      
      The kernel may crash when block size is changed and I/O is issued
      simultaneously.
      
      Because some subsystems (udev or lvm) may read any block device anytime,
      the bug actually puts any code that changes a block device size in
      jeopardy.
      
      The crash can be reproduced if you place "msleep(1000)" to
      blkdev_get_blocks just before "bh->b_size = max_blocks <<
      inode->i_blkbits;".
      Then, run "dd if=/dev/ram0 of=/dev/null bs=4k count=1 iflag=direct"
      While it is waiting in msleep, run "blockdev --setbsz 2048 /dev/ram0"
      You get a BUG.
      
      The direct and non-direct I/O is written with the assumption that block
      size does not change. It doesn't seem practical to fix these crashes
      one-by-one there may be many crash possibilities when block size changes
      at a certain place and it is impossible to find them all and verify the
      code.
      
      This patch introduces a new rw-lock bd_block_size_semaphore. The lock is
      taken for read during I/O. It is taken for write when changing block
      size. Consequently, block size can't be changed while I/O is being
      submitted.
      
      For asynchronous I/O, the patch only prevents block size change while
      the I/O is being submitted. The block size can change when the I/O is in
      progress or when the I/O is being finished. This is acceptable because
      there are no accesses to block size when asynchronous I/O is being
      finished.
      
      The patch prevents block size changing while the device is mapped with
      mmap.
      Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      b87570f5
  2. 20 Sep, 2012 1 commit
  3. 03 Aug, 2012 1 commit
    • Artem Bityutskiy's avatar
      vfs: kill write_super and sync_supers · f0cd2dbb
      Artem Bityutskiy authored
      
      
      Finally we can kill the 'sync_supers' kernel thread along with the
      '->write_super()' superblock operation because all the users are gone.
      Now every file-system is supposed to self-manage own superblock and
      its dirty state.
      
      The nice thing about killing this thread is that it improves power management.
      Indeed, 'sync_supers' is a source of monotonic system wake-ups - it woke up
      every 5 seconds no matter what - even if there were no dirty superblocks and
      even if there were no file-systems using this service (e.g., btrfs and
      journalled ext4 do not need it). So it was wasting power most of the time. And
      because the thread was in the core of the kernel, all systems had to have it.
      So I am quite happy to make it go away.
      
      Interestingly, this thread is a left-over from the pdflush kernel thread which
      was a self-forking kernel thread responsible for all the write-back in old
      Linux kernels. It was turned into per-block device BDI threads, and
      'sync_supers' was a left-over. Thus, R.I.P, pdflush as well.
      Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      f0cd2dbb
  4. 01 Aug, 2012 4 commits
    • J. Bruce Fields's avatar
      locks: remove unused lm_release_private · 068535f1
      J. Bruce Fields authored
      In commit 3b6e2723
      
       ("locks: prevent side-effects of
      locks_release_private before file_lock is initialized") we removed the
      last user of lm_release_private without removing the field itself.
      Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      068535f1
    • Mel Gorman's avatar
      mm: swap: implement generic handler for swap_activate · a509bc1a
      Mel Gorman authored
      
      
      The version of swap_activate introduced is sufficient for swap-over-NFS
      but would not provide enough information to implement a generic handler.
      This patch shuffles things slightly to ensure the same information is
      available for aops->swap_activate() as is available to the core.
      
      No functionality change.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Eric B Munson <emunson@mgebm.net>
      Cc: Eric Paris <eparis@redhat.com>
      Cc: James Morris <jmorris@namei.org>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Mike Christie <michaelc@cs.wisc.edu>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
      Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
      Cc: Xiaotian Feng <dfeng@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a509bc1a
    • Mel Gorman's avatar
      mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages · 62c230bc
      Mel Gorman authored
      
      
      Currently swapfiles are managed entirely by the core VM by using ->bmap to
      allocate space and write to the blocks directly.  This effectively ensures
      that the underlying blocks are allocated and avoids the need for the swap
      subsystem to locate what physical blocks store offsets within a file.
      
      If the swap subsystem is to use the filesystem information to locate the
      blocks, it is critical that information such as block groups, block
      bitmaps and the block descriptor table that map the swap file were
      resident in memory.  This patch adds address_space_operations that the VM
      can call when activating or deactivating swap backed by a file.
      
        int swap_activate(struct file *);
        int swap_deactivate(struct file *);
      
      The ->swap_activate() method is used to communicate to the file that the
      VM relies on it, and the address_space should take adequate measures such
      as reserving space in the underlying device, reserving memory for mempools
      and pinning information such as the block descriptor table in memory.  The
      ->swap_deactivate() method is called on sys_swapoff() if ->swap_activate()
      returned success.
      
      After a successful swapfile ->swap_activate, the swapfile is marked
      SWP_FILE and swapper_space.a_ops will proxy to
      sis->swap_file->f_mappings->a_ops using ->direct_io to write swapcache
      pages and ->readpage to read.
      
      It is perfectly possible that direct_IO be used to read the swap pages but
      it is an unnecessary complication.  Similarly, it is possible that
      ->writepage be used instead of direct_io to write the pages but filesystem
      developers have stated that calling writepage from the VM is undesirable
      for a variety of reasons and using direct_IO opens up the possibility of
      writing back batches of swap pages in the future.
      
      [a.p.zijlstra@chello.nl: Original patch]
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Eric B Munson <emunson@mgebm.net>
      Cc: Eric Paris <eparis@redhat.com>
      Cc: James Morris <jmorris@namei.org>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Mike Christie <michaelc@cs.wisc.edu>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
      Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
      Cc: Xiaotian Feng <dfeng@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      62c230bc
    • Mel Gorman's avatar
      mm: add get_kernel_page[s] for pinning of kernel addresses for I/O · 18022c5d
      Mel Gorman authored
      
      
      This patch adds two new APIs get_kernel_pages() and get_kernel_page() that
      may be used to pin a vector of kernel addresses for IO.  The initial user
      is expected to be NFS for allowing pages to be written to swap using
      aops->direct_IO().  Strictly speaking, swap-over-NFS only needs to pin one
      page for IO but it makes sense to express the API in terms of a vector and
      add a helper for pinning single pages.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Eric B Munson <emunson@mgebm.net>
      Cc: Eric Paris <eparis@redhat.com>
      Cc: James Morris <jmorris@namei.org>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Mike Christie <michaelc@cs.wisc.edu>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
      Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
      Cc: Xiaotian Feng <dfeng@redhat.com>
      Cc: Mark Salter <msalter@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      18022c5d
  5. 31 Jul, 2012 2 commits
  6. 29 Jul, 2012 2 commits
    • Kees Cook's avatar
      fs: add link restrictions · 800179c9
      Kees Cook authored
      This adds symlink and hardlink restrictions to the Linux VFS.
      
      Symlinks:
      
      A long-standing class of security issues is the symlink-based
      time-of-check-time-of-use race, most commonly seen in world-writable
      directories like /tmp. The common method of exploitation of this flaw
      is to cross privilege boundaries when following a given symlink (i.e. a
      root process follows a symlink belonging to another user). For a likely
      incomplete list of hundreds of examples across the years, please see:
      http://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=/tmp
      
      The solution is to permit symlinks to only be followed when outside
      a sticky world-writable directory, or when the uid of the symlink and
      follower match, or when the directory owner matches the symlink's owner.
      
      Some pointers to the history of earlier discussion that I could find:
      
       1996 Aug, Zygo Blaxell
        http://marc.info/?l=bugtraq&m=87602167419830&w=2
       1996 Oct, Andrew Tridgell
        http://lkml.indiana.edu/hypermail/linux/kernel/9610.2/0086.html
       1997 Dec, Albert D Cahalan
        http://lkml.org/lkml/1997/12/16/4
       2005 Feb, Lorenzo Hernández García-Hierro
        http://lkml.indiana.edu/hypermail/linux/kernel/0502.0/1896.html
       2010 May, Kees Cook
        https://lkml.org/lkml/2010/5/30/144
      
      Past objections and rebuttals could be summarized as:
      
       - Violates POSIX.
         - POSIX didn't consider this situation and it's not useful to follow
           a broken specification at the cost of security.
       - Might break unknown applications that use this feature.
         - Applications that break because of the change are easy to spot and
           fix. Applications that are vulnerable to symlink ToCToU by not having
           the change aren't. Additionally, no applications have yet been found
           that rely on this behavior.
       - Applications should just use mkstemp() or O_CREATE|O_EXCL.
         - True, but applications are not perfect, and new software is written
           all the time that makes these mistakes; blocking this flaw at the
           kernel is a single solution to the entire class of vulnerability.
       - This should live in the core VFS.
         - This should live in an LSM. (https://lkml.org/lkml/2010/5/31/135)
       - This should live in an LSM.
         - This should live in the core VFS. (https://lkml.org/lkml/2010/8/2/188)
      
      Hardlinks:
      
      On systems that have user-writable directories on the same partition
      as system files, a long-standing class of security issues is the
      hardlink-based time-of-check-time-of-use race, most commonly seen in
      world-writable directories like /tmp. The common method of exploitation
      of this flaw is to cross privilege boundaries when following a given
      hardlink (i.e. a root process follows a hardlink created by another
      user). Additionally, an issue exists where users can "pin" a potentially
      vulnerable setuid/setgid file so that an administrator will not actually
      upgrade a system fully.
      
      The solution is to permit hardlinks to only be created when the user is
      already the existing file's owner, or if they already have read/write
      access to the existing file.
      
      Many Linux users are surprised when they learn they can link to files
      they have no access to, so this change appears to follow the doctrine
      of "least surprise". Additionally, this change does not violate POSIX,
      which states "the implementation may require that the calling process
      has permission to access the existing file"[1].
      
      This change is known to break some implementations of the "at" daemon,
      though the version used by Fedora and Ubuntu has been fixed[2] for
      a while. Otherwise, the change has been undisruptive while in use in
      Ubuntu for the last 1.5 years.
      
      [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/linkat.html
      [2] http://anonscm.debian.org/gitweb/?p=collab-maint/at.git;a=commitdiff;h=f4114656c3a6c6f6070e315ffdf940a49eda3279
      
      
      
      This patch is based on the patches in Openwall and grsecurity, along with
      suggestions from Al Viro. I have added a sysctl to enable the protected
      behavior, and documentation.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      800179c9
    • Al Viro's avatar
      consolidate pipe file creation · e4fad8e5
      Al Viro authored
      
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      e4fad8e5
  7. 27 Jul, 2012 1 commit
  8. 22 Jul, 2012 3 commits
  9. 14 Jul, 2012 10 commits
  10. 03 Jun, 2012 1 commit
    • Linus Torvalds's avatar
      vfs: move inode stat information closer together · 2f9d3df8
      Linus Torvalds authored
      
      
      The comment above it says "Stat data, not accessed from path walking",
      but in fact some of inode fields we use for the common stat data was way
      down at the end of the inode, causing unnecessary cache misses for the
      common stat operations.
      
      The inode structure is pretty big, and this can change padding depending
      on field width, but at least on the common 64-bit configurations this
      doesn't change the size.  Some of our inode layout has historically been
      to tro to avoid unnecessary padding fields, but cache locality is at
      least as important for layout, if not more.
      
      Noticed by looking at kernel profiles, and noticing that the "i_blkbits"
      access stood out like a sore thumb.
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2f9d3df8
  11. 01 Jun, 2012 2 commits
    • Josef Bacik's avatar
      fs: introduce inode operation ->update_time · c3b2da31
      Josef Bacik authored
      
      
      Btrfs has to make sure we have space to allocate new blocks in order to modify
      the inode, so updating time can fail.  We've gotten around this by having our
      own file_update_time but this is kind of a pain, and Christoph has indicated he
      would like to make xfs do something different with atime updates.  So introduce
      ->update_time, where we will deal with i_version an a/m/c time updates and
      indicate which changes need to be made.  The normal version just does what it
      has always done, updates the time and marks the inode dirty, and then
      filesystems can choose to do something different.
      
      I've gone through all of the users of file_update_time and made them check for
      errors with the exception of the fault code since it's complicated and I wasn't
      quite sure what to do there, also Jan is going to be pushing the file time
      updates into page_mkwrite for those who have it so that should satisfy btrfs and
      make it not a big deal to check the file_update_time() return code in the
      generic fault path. Thanks,
      Signed-off-by: default avatarJosef Bacik <josef@redhat.com>
      c3b2da31
    • Christopher Yeoh's avatar
      aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() · ac34ebb3
      Christopher Yeoh authored
      
      
      A cleanup of rw_copy_check_uvector and compat_rw_copy_check_uvector after
      changes made to support CMA in an earlier patch.
      
      Rather than having an additional check_access parameter to these
      functions, the first paramater type is overloaded to allow the caller to
      specify CHECK_IOVEC_ONLY which means check that the contents of the iovec
      are valid, but do not check the memory that they point to.  This is used
      by process_vm_readv/writev where we need to validate that a iovec passed
      to the syscall is valid but do not want to check the memory that it points
      to at this point because it refers to an address space in another process.
      Signed-off-by: default avatarChris Yeoh <yeohc@au1.ibm.com>
      Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ac34ebb3
  12. 31 May, 2012 1 commit
  13. 29 May, 2012 1 commit
  14. 11 May, 2012 1 commit
    • Jeff Moyer's avatar
      block: don't mark buffers beyond end of disk as mapped · 080399aa
      Jeff Moyer authored
      
      
      Hi,
      
      We have a bug report open where a squashfs image mounted on ppc64 would
      exhibit errors due to trying to read beyond the end of the disk.  It can
      easily be reproduced by doing the following:
      
      [root@ibm-p750e-02-lp3 ~]# ls -l install.img
      -rw-r--r-- 1 root root 142032896 Apr 30 16:46 install.img
      [root@ibm-p750e-02-lp3 ~]# mount -o loop ./install.img /mnt/test
      [root@ibm-p750e-02-lp3 ~]# dd if=/dev/loop0 of=/dev/null
      dd: reading `/dev/loop0': Input/output error
      277376+0 records in
      277376+0 records out
      142016512 bytes (142 MB) copied, 0.9465 s, 150 MB/s
      
      In dmesg, you'll find the following:
      
      squashfs: version 4.0 (2009/01/31) Phillip Lougher
      [   43.106012] attempt to access beyond end of device
      [   43.106029] loop0: rw=0, want=277410, limit=277408
      [   43.106039] Buffer I/O error on device loop0, logical block 138704
      [   43.106053] attempt to access beyond end of device
      [   43.106057] loop0: rw=0, want=277412, limit=277408
      [   43.106061] Buffer I/O error on device loop0, logical block 138705
      [   43.106066] attempt to access beyond end of device
      [   43.106070] loop0: rw=0, want=277414, limit=277408
      [   43.106073] Buffer I/O error on device loop0, logical block 138706
      [   43.106078] attempt to access beyond end of device
      [   43.106081] loop0: rw=0, want=277416, limit=277408
      [   43.106085] Buffer I/O error on device loop0, logical block 138707
      [   43.106089] attempt to access beyond end of device
      [   43.106093] loop0: rw=0, want=277418, limit=277408
      [   43.106096] Buffer I/O error on device loop0, logical block 138708
      [   43.106101] attempt to access beyond end of device
      [   43.106104] loop0: rw=0, want=277420, limit=277408
      [   43.106108] Buffer I/O error on device loop0, logical block 138709
      [   43.106112] attempt to access beyond end of device
      [   43.106116] loop0: rw=0, want=277422, limit=277408
      [   43.106120] Buffer I/O error on device loop0, logical block 138710
      [   43.106124] attempt to access beyond end of device
      [   43.106128] loop0: rw=0, want=277424, limit=277408
      [   43.106131] Buffer I/O error on device loop0, logical block 138711
      [   43.106135] attempt to access beyond end of device
      [   43.106139] loop0: rw=0, want=277426, limit=277408
      [   43.106143] Buffer I/O error on device loop0, logical block 138712
      [   43.106147] attempt to access beyond end of device
      [   43.106151] loop0: rw=0, want=277428, limit=277408
      [   43.106154] Buffer I/O error on device loop0, logical block 138713
      [   43.106158] attempt to access beyond end of device
      [   43.106162] loop0: rw=0, want=277430, limit=277408
      [   43.106166] attempt to access beyond end of device
      [   43.106169] loop0: rw=0, want=277432, limit=277408
      ...
      [   43.106307] attempt to access beyond end of device
      [   43.106311] loop0: rw=0, want=277470, limit=2774
      
      Squashfs manages to read in the end block(s) of the disk during the
      mount operation.  Then, when dd reads the block device, it leads to
      block_read_full_page being called with buffers that are beyond end of
      disk, but are marked as mapped.  Thus, it would end up submitting read
      I/O against them, resulting in the errors mentioned above.  I fixed the
      problem by modifying init_page_buffers to only set the buffer mapped if
      it fell inside of i_size.
      
      Cheers,
      Jeff
      Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Acked-by: default avatarNick Piggin <npiggin@kernel.dk>
      
      --
      
      Changes from v1->v2: re-used max_block, as suggested by Nick Piggin.
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      080399aa
  15. 06 May, 2012 2 commits
    • Jan Kara's avatar
      writeback: Avoid iput() from flusher thread · 169ebd90
      Jan Kara authored
      
      
      Doing iput() from flusher thread (writeback_sb_inodes()) can create problems
      because iput() can do a lot of work - for example truncate the inode if it's
      the last iput on unlinked file. Some filesystems depend on flusher thread
      progressing (e.g. because they need to flush delay allocated blocks to reduce
      allocation uncertainty) and so flusher thread doing truncate creates
      interesting dependencies and possibilities for deadlocks.
      
      We get rid of iput() in flusher thread by using the fact that I_SYNC inode
      flag effectively pins the inode in memory. So if we take care to either hold
      i_lock or have I_SYNC set, we can get away without taking inode reference
      in writeback_sb_inodes().
      
      As a side effect of these changes, we also fix possible use-after-free in
      wb_writeback() because inode_wait_for_writeback() call could try to reacquire
      i_lock on the inode that was already free.
      Signed-off-by: default avatarJan Kara <jack@suse.cz>
      Signed-off-by: default avatarFengguang Wu <fengguang.wu@intel.com>
      169ebd90
    • Jan Kara's avatar
      vfs: Rename end_writeback() to clear_inode() · dbd5768f
      Jan Kara authored
      
      
      After we moved inode_sync_wait() from end_writeback() it doesn't make sense
      to call the function end_writeback() anymore. Rename it to clear_inode()
      which well says what the function really does - set I_CLEAR flag.
      Signed-off-by: default avatarJan Kara <jack@suse.cz>
      Signed-off-by: default avatarFengguang Wu <fengguang.wu@intel.com>
      dbd5768f
  16. 03 May, 2012 1 commit
  17. 08 Apr, 2012 1 commit
    • Eric W. Biederman's avatar
      userns: Replace the hard to write inode_userns with inode_capable. · 1a48e2ac
      Eric W. Biederman authored
      
      
      This represents a change in strategy of how to handle user namespaces.
      Instead of tagging everything explicitly with a user namespace and bulking
      up all of the comparisons of uids and gids in the kernel,  all uids and gids
      in use will have a mapping to a flat kuid and kgid spaces respectively.  This
      allows much more of the existing logic to be preserved and in general
      allows for faster code.
      
      In this new and improved world we allow someone to utiliize capabilities
      over an inode if the inodes owner mapps into the capabilities holders user
      namespace and the user has capabilities in their user namespace.  Which
      is simple and efficient.
      
      Moving the fs uid comparisons to be comparisons in a flat kuid space
      follows in later patches, something that is only significant if you
      are using user namespaces.
      Acked-by: default avatarSerge Hallyn <serge.hallyn@canonical.com>
      Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      1a48e2ac
  18. 05 Apr, 2012 1 commit
  19. 01 Apr, 2012 1 commit
  20. 22 Mar, 2012 1 commit
    • Artem Bityutskiy's avatar
      vfs: remove unused superblock helpers · 9d547c35
      Artem Bityutskiy authored
      
      
      Remove the 'sb_mark_dirty()', 'sb_mark_clean()' and 'sb_is_dirty()'
      helpers which are not used. I introduced them 2 years and the
      intention was to make all file-systems use them in order to be able to
      optimize 'sync_supers()'.  However, Al Viro vetoed my patches at the
      end and asked me to push superblock management down to file-systems
      and get rid of the 's_dirt' flag completely, as well as kill
      'sync_supers()' altogether. Thus, remove the helpers.
      Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      9d547c35
  21. 21 Mar, 2012 1 commit