1. 31 Mar, 2014 14 commits
    • Jeff Layton's avatar
      locks: add new fcntl cmd values for handling file private locks · 5d50ffd7
      Jeff Layton authored
      Due to some unfortunate history, POSIX locks have very strange and
      unhelpful semantics. The thing that usually catches people by surprise
      is that they are dropped whenever the process closes any file descriptor
      associated with the inode.
      
      This is extremely problematic for people developing file servers that
      need to implement byte-range locks. Developers often need a "lock
      management" facility to ensure that file descriptors are not closed
      until all of the locks associated with the inode are finished.
      
      Additionally, "classic" POSIX locks are owned by the process. Locks
      taken between threads within the same process won't conflict with one
      another, which renders them useless for synchronization between threads.
      
      This patchset adds a new type of lock that attempts to address these
      issues. These locks conflict with classic POSIX read/write locks, but
      have semantics that are more like BSD locks with respect to inheritance
      and behavior on close.
      
      This is implemented primarily by changing how fl_owner field is set for
      these locks. Instead of having them owned by the files_struct of the
      process, they are instead owned by the filp on which they were acquired.
      Thus, they are inherited across fork() and are only released when the
      last reference to a filp is put.
      
      These new semantics prevent them from being merged with classic POSIX
      locks, even if they are acquired by the same process. These locks will
      also conflict with classic POSIX locks even if they are acquired by
      the same process or on the same file descriptor.
      
      The new locks are managed using a new set of cmd values to the fcntl()
      syscall. The initial implementation of this converts these values to
      "classic" cmd values at a fairly high level, and the details are not
      exposed to the underlying filesystem. We may eventually want to push
      this handing out to the lower filesystem code but for now I don't
      see any need for it.
      
      Also, note that with this implementation the new cmd values are only
      available via fcntl64() on 32-bit arches. There's little need to
      add support for legacy apps on a new interface like this.
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      5d50ffd7
    • Jeff Layton's avatar
      locks: skip deadlock detection on FL_FILE_PVT locks · 57b65325
      Jeff Layton authored
      It's not really feasible to do deadlock detection with FL_FILE_PVT
      locks since they aren't owned by a single task, per-se. Deadlock
      detection also tends to be rather expensive so just skip it for
      these sorts of locks.
      
      Also, add a FIXME comment about adding more limited deadlock detection
      that just applies to ro -> rw upgrades, per Andy's request.
      
      Cc: Andy Lutomirski <luto@amacapital.net>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      57b65325
    • Jeff Layton's avatar
      locks: pass the cmd value to fcntl_getlk/getlk64 · c1e62b8f
      Jeff Layton authored
      Once we introduce file private locks, we'll need to know what cmd value
      was used, as that affects the ownership and whether a conflict would
      arise.
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      c1e62b8f
    • Jeff Layton's avatar
      locks: report l_pid as -1 for FL_FILE_PVT locks · 3fd80cdd
      Jeff Layton authored
      FL_FILE_PVT locks are no longer tied to a particular pid, and are
      instead inheritable by child processes. Report a l_pid of '-1' for
      these sorts of locks since the pid is somewhat meaningless for them.
      
      This precedent comes from FreeBSD. There, POSIX and flock() locks can
      conflict with one another. If fcntl(F_GETLK, ...) returns a lock set
      with flock() then the l_pid member cannot be a process ID because the
      lock is not held by a process as such.
      Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      3fd80cdd
    • Jeff Layton's avatar
      locks: make /proc/locks show IS_FILE_PVT locks as type "FLPVT" · c918d42a
      Jeff Layton authored
      In a later patch, we'll be adding a new type of lock that's owned by
      the struct file instead of the files_struct. Those sorts of locks
      will be flagged with a new FL_FILE_PVT flag.
      
      Report these types of locks as "FLPVT" in /proc/locks to distinguish
      them from "classic" POSIX locks.
      Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      c918d42a
    • Jeff Layton's avatar
      locks: rename locks_remove_flock to locks_remove_file · 78ed8a13
      Jeff Layton authored
      This function currently removes leases in addition to flock locks and in
      a later patch we'll have it deal with file-private locks too. Rename it
      to locks_remove_file to indicate that it removes locks that are
      associated with a particular struct file, and not just flock locks.
      Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      78ed8a13
    • Jeff Layton's avatar
      locks: consolidate checks for compatible filp->f_mode values in setlk handlers · bce7560d
      Jeff Layton authored
      Move this check into flock64_to_posix_lock instead of duplicating it in
      two places. This also fixes a minor wart in the code where we continue
      referring to the struct flock after converting it to struct file_lock.
      Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      bce7560d
    • J. Bruce Fields's avatar
      locks: fix posix lock range overflow handling · ef12e72a
      J. Bruce Fields authored
      In the 32-bit case fcntl assigns the 64-bit f_pos and i_size to a 32-bit
      off_t.
      
      The existing range checks also seem to depend on signed arithmetic
      wrapping when it overflows.  In practice maybe that works, but we can be
      more careful.  That also allows us to make a more reliable distinction
      between -EINVAL and -EOVERFLOW.
      
      Note that in the 32-bit case SEEK_CUR or SEEK_END might allow the caller
      to set a lock with starting point no longer representable as a 32-bit
      value.  We could return -EOVERFLOW in such cases, but the locks code is
      capable of handling such ranges, so we choose to be lenient here.  The
      only problem is that subsequent GETLK calls on such a lock will fail
      with EOVERFLOW.
      
      While we're here, do some cleanup including consolidating code for the
      flock and flock64 cases.
      Signed-off-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      ef12e72a
    • Jeff Layton's avatar
      locks: eliminate BUG() call when there's an unexpected lock on file close · 8c3cac5e
      Jeff Layton authored
      A leftover lock on the list is surely a sign of a problem of some sort,
      but it's not necessarily a reason to panic the box. Instead, just log a
      warning with some info about the lock, and then delete it like we would
      any other lock.
      
      In the event that the filesystem declares a ->lock f_op, we may end up
      leaking something, but that's generally preferable to an immediate
      panic.
      Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      8c3cac5e
    • Jeff Layton's avatar
      b03dfdec
    • Jeff Layton's avatar
      locks: remove "inline" qualifier from fl_link manipulation functions · 6ca10ed8
      Jeff Layton authored
      It's best to let the compiler decide that.
      Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      6ca10ed8
    • Jeff Layton's avatar
      locks: clean up comment typo · 46dad760
      Jeff Layton authored
      Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      46dad760
    • Jeff Layton's avatar
      locks: close potential race between setlease and open · 24cbe784
      Jeff Layton authored
      As Al Viro points out, there is an unlikely, but possible race between
      opening a file and setting a lease on it. generic_add_lease is done with
      the i_lock held, but the inode->i_flock check in break_lease is
      lockless. It's possible for another task doing an open to do the entire
      pathwalk and call break_lease between the point where generic_add_lease
      checks for a conflicting open and adds the lease to the list. If this
      occurs, we can end up with a lease set on the file with a conflicting
      open.
      
      To guard against that, check again for a conflicting open after adding
      the lease to the i_flock list. If the above race occurs, then we can
      simply unwind the lease setting and return -EAGAIN.
      
      Because we take dentry references and acquire write access on the file
      before calling break_lease, we know that if the i_flock list is empty
      when the open caller goes to check it then the necessary refcounts have
      already been incremented. Thus the additional check for a conflicting
      open will see that there is one and the setlease call will fail.
      
      Cc: Bruce Fields <bfields@fieldses.org>
      Cc: David Howells <dhowells@redhat.com>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Reported-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      Signed-off-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
      24cbe784
    • Jeff Layton's avatar
      MAINTAINERS: update entry for fs/locks.c · 18156e7e
      Jeff Layton authored
      Both Bruce and I have done a fair bit of work in these files recently,
      and would like to be notified if anyone is proposing changes to it.
      
      Also, Matthew is no longer interested in maintaining this code, so
      remove him.
      
      Cc: Matthew Wilcox <matthew@wil.cx>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      Acked-by: default avatar"J. Bruce Fields" <bfields@fieldses.org>
      18156e7e
  2. 03 Feb, 2014 4 commits
    • Linus Torvalds's avatar
      Linus 3.14-rc1 · 38dbfb59
      Linus Torvalds authored
      38dbfb59
    • Linus Torvalds's avatar
      Merge branch 'parisc-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux · 69048e01
      Linus Torvalds authored
      Pull parisc updates from Helge Deller:
       "The three major changes in this patchset is a implementation for
        flexible userspace memory maps, cache-flushing fixes (again), and a
        long-discussed ABI change to make EWOULDBLOCK the same value as
        EAGAIN.
      
        parisc has been the only platform where we had EWOULDBLOCK != EAGAIN
        to keep HP-UX compatibility.  Since we will probably never implement
        full HP-UX support, we prefer to drop this compatibility to make it
        easier for us with Linux userspace programs which mostly never checked
        for both values.  We don't expect major fall-outs because of this
        change, and if we face some, we will simply rebuild the necessary
        applications in the debian archives"
      
      * 'parisc-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
        parisc: add flexible mmap memory layout support
        parisc: Make EWOULDBLOCK be equal to EAGAIN on parisc
        parisc: convert uapi/asm/stat.h to use native types only
        parisc: wire up sched_setattr and sched_getattr
        parisc: fix cache-flushing
        parisc/sti_console: prefer Linux fonts over built-in ROM fonts
      69048e01
    • Mikulas Patocka's avatar
      hpfs: optimize quad buffer loading · 1c0b8a7a
      Mikulas Patocka authored
      HPFS needs to load 4 consecutive 512-byte sectors when accessing the
      directory nodes or bitmaps.  We can't switch to 2048-byte block size
      because files are allocated in the units of 512-byte sectors.
      
      Previously, the driver would allocate a 2048-byte area using kmalloc,
      copy the data from four buffers to this area and eventually copy them
      back if they were modified.
      
      In the current implementation of the buffer cache, buffers are allocated
      in the pagecache.  That means that 4 consecutive 512-byte buffers are
      stored in consecutive areas in the kernel address space.  So, we don't
      need to allocate extra memory and copy the content of the buffers there.
      
      This patch optimizes the code to avoid copying the buffers.  It checks
      if the four buffers are stored in contiguous memory - if they are not,
      it falls back to allocating a 2048-byte area and copying data there.
      Signed-off-by: default avatarMikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1c0b8a7a
    • Mikulas Patocka's avatar
      hpfs: remember free space · 2cbe5c76
      Mikulas Patocka authored
      Previously, hpfs scanned all bitmaps each time the user asked for free
      space using statfs.  This patch changes it so that hpfs scans the
      bitmaps only once, remembes the free space and on next invocation of
      statfs it returns the value instantly.
      
      New versions of wine are hammering on the statfs syscall very heavily,
      making some games unplayable when they're stored on hpfs, with load
      times in minutes.
      
      This should be backported to the stable kernels because it fixes
      user-visible problem (excessive level load times in wine).
      Signed-off-by: default avatarMikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2cbe5c76
  3. 02 Feb, 2014 12 commits
  4. 01 Feb, 2014 10 commits