[RTEMS Project] #3689: bdbuf: Replace automatic read-ahead with rtems_bdbuf_peek()

[RTEMS trac]

#3689: bdbuf: Replace automatic read-ahead with rtems_bdbuf_peek()
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  Reporter:  Sebastian Huber  |      Owner:  Sebastian Huber
      Type:  enhancement      |     Status:  assigned
  Priority:  normal           |  Milestone:  5.1
 Component:  lib/block        |    Version:  5
  Severity:  normal           |   Keywords:
Blocked By:                   |   Blocking:
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 The block device cache (bdbuf) tries to deduce a read ahead opportunity
 from the read access pattern. Using real world FAT file systems showed
 that this is not very reliable and the read ahead seldom happens. One way
 to fix this issue is let file systems give a hint to the block device
 cache that they will likely read a certain block in the future, e.g. the
 next block in a sequential file read. Remove the existing read ahead logic
 and add a new function rtems_bdbuf_peek() instead.

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Ticket URL: <http://devel.rtems.org/ticket/3689>
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