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  1. 10 Mar, 2011 11 commits
  2. 13 Nov, 2010 1 commit
    • Tejun Heo's avatar
      block: make blkdev_get/put() handle exclusive access · e525fd89
      Tejun Heo authored
      Over time, block layer has accumulated a set of APIs dealing with bdev
      open, close, claim and release.
      
      * blkdev_get/put() are the primary open and close functions.
      
      * bd_claim/release() deal with exclusive open.
      
      * open/close_bdev_exclusive() are combination of open and claim and
        the other way around, respectively.
      
      * bd_link/unlink_disk_holder() to create and remove holder/slave
        symlinks.
      
      * open_by_devnum() wraps bdget() + blkdev_get().
      
      The interface is a bit confusing and the decoupling of open and claim
      makes it impossible to properly guarantee exclusive access as
      in-kernel open + claim sequence can disturb the existing exclusive
      open even before the block layer knows the current open if for another
      exclusive access.  Reorganize the interface such that,
      
      * blkdev_get() is extended to include exclusive access management.
        @holder argument is added and, if is @FMODE_EXCL specified, it will
        gain exclusive access atomically w.r.t. other exclusive accesses.
      
      * blkdev_put() is similarly extended.  It now takes @mode argument and
        if @FMODE_EXCL is set, it releases an exclusive access.  Also, when
        the last exclusive claim is released, the holder/slave symlinks are
        removed automatically.
      
      * bd_claim/release() and close_bdev_exclusive() are no longer
        necessary and either made static or removed.
      
      * bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
        is no longer necessary and removed.
      
      * open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
        and blkdev_get().  It also has an unexpected extra bdev_read_only()
        test which probably should be moved into blkdev_get().
      
      * open_by_devnum() is modified to take @holder argument and pass it to
        blkdev_get().
      
      Most of bdev open/close operations are unified into blkdev_get/put()
      and most exclusive accesses are tested atomically at the open time (as
      it should).  This cleans up code and removes some, both valid and
      invalid, but unnecessary all the same, corner cases.
      
      open_bdev_exclusive() and open_by_devnum() can use further cleanup -
      rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
      special features.  Well, let's leave them for another day.
      
      Most conversions are straight-forward.  drbd conversion is a bit more
      involved as there was some reordering, but the logic should stay the
      same.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarNeil Brown <neilb@suse.de>
      Acked-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
      Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
      Acked-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
      Cc: Peter Osterlund <petero2@telia.com>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Andreas Dilger <adilger.kernel@dilger.ca>
      Cc: "Theodore Ts'o" <tytso@mit.edu>
      Cc: Mark Fasheh <mfasheh@suse.com>
      Cc: Joel Becker <joel.becker@oracle.com>
      Cc: Alex Elder <aelder@sgi.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: dm-devel@redhat.com
      Cc: drbd-dev@lists.linbit.com
      Cc: Leo Chen <leochen@broadcom.com>
      Cc: Scott Branden <sbranden@broadcom.com>
      Cc: Chris Mason <chris.mason@oracle.com>
      Cc: Steven Whitehouse <swhiteho@redhat.com>
      Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
      Cc: Joern Engel <joern@logfs.org>
      Cc: reiserfs-devel@vger.kernel.org
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      e525fd89
  3. 10 Nov, 2010 1 commit
  4. 23 Oct, 2010 3 commits
  5. 22 Oct, 2010 2 commits
  6. 14 Oct, 2010 22 commits