git: DragonFly_RELEASE_2_8 kernel - Hold vm_token() for certain buf/bio/vm_page interactions

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxxxxx>]

commit 3730eb0ba85c1be539aa4917aeefaa78f00a8946
Author: Matthew Dillon <dillon@apollo.backplane.com>
Date:   Sat Nov 27 22:28:52 2010 -0800

    kernel - Hold vm_token() for certain buf/bio/vm_page interactions
    
    * Hold the vm_token when messing around with page valid and dirty bits
      in buffer cache operations.  Such race conditions are possible but would
      be very rare.
    
    * Fix inconsistent use of bio2.bio_offset when swapcache intercepts an
      I/O operation.  When this case occurs the normal filesystem VOP_STRATEGY
      function will not be called and any assumption that bio2.bio_offset
      will represent a block device offset will be invalid.
    
      To deal with this case swapcache will re-set bio_offset to NOOFFSET.
      Filesystems use this value to determine that no block device offset
      has been cached for a logical file block.
    
    Reported-by: Jan Lentfer <Jan.Lentfer@web.de> (bio_offset issue)

Summary of changes:
 sys/kern/vfs_bio.c |   47 +++++++++++++++++++++++++++++++++++++++--------
 1 files changed, 39 insertions(+), 8 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/3730eb0ba85c1be539aa4917aeefaa78f00a8946


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