Manual Pages for UNIX Operating System command usage for man biomodified

Kernel Functions for Drivers                      biomodified(9F)



NAME
     biomodified - check if a buffer is modified

SYNOPSIS
     #include 
     #include 

     int biomodified(struct buf *bp);


INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI).

PARAMETERS
     bp    Pointer to the buffer header structure.


DESCRIPTION
     The biomodified() function returns status to indicate if the
     buffer is modified. The  biomodified() function is only sup-
     ported for paged- I/O request, that is the B_PAGEIOflag must
     be  set  in the b_flags field of the buf(9S) structure.  The
     biomodified() function will check the memory  pages  associ-
     ated  with  this  buffer whether the Virtual Memory system's
     modification bit is set.  If at least one of these pages  is
     modified, the buffer is indicated as modified.  A filesystem
     will mark the pages  unmodified when it writes the pages  to
     the  backing store.  The  biomodified() function can be used
     to detect any modifications to the memory pages while I/O is
     in progress.


     A device driver can use biomodified()  for  disk  mirroring.
     An  application  is allowed to mmap a file which can  reside
     on a disk which is mirrored by multiple submirrors.  If  the
     file  system  writes  the  file  to the backing store, it is
     written to all  submirrors in parallel. It must  be  ensured
     that  the copies on all submirrors are identical. The biomo-
     dified() function can be used in the device driver to detect
     any  modifications to  the buffer by the user program during
     the time the buffer is written to multiple submirrors.

RETURN VALUES
     The  biomodified() function returns the following values:

     1     Buffer is modified.


     0     Buffer is not modified.






SunOS 5.11          Last change: 20 Nov 1996                    1






Kernel Functions for Drivers                      biomodified(9F)



     -1    Buffer is not used for paged I/O request.


CONTEXT
     biomodified() can be called from any context.

SEE ALSO
     bp_mapin(9F), buf(9S)


     Writing Device Drivers












































SunOS 5.11          Last change: 20 Nov 1996                    2