Commit graph

5 commits

Author SHA1 Message Date
Ben Gras
d844d2a547 Fixed nasty bug that would cause FS to loop forever in rw_scattered (while
syncing, for instance) if blocks are unwritable. This could happen if:

  . write goes beyond device boundary to a block device
  . write is done for a complete block or more; thus the
    block is not retrieved first (at which point it would be noticed
    it doesn't exist), but the buffer is simply allocated
  . at write time, the device i/o doesn't succeed, but rw_scattered
    doesn't understand this and loops forever trying to get the block
    written.

Currently, if no blocks can be written, the loop aborts, leaving all
buffers intact but potentially dirty. When invalidate() is called on the
device, the buffers will disappear (even if dirty). Same story for if
the buffer is removed due to rmed from lru chain. There's not much we
can do about this, however - we can't keep these blocks around, forever
occupying a buffer in the buffer cache.

The second part of the solution is not to let unwritable buffers be
created in the first place. How to do this, however, without doing a
wasteful read first?

It looks like this code was in 2.0.4 too.
2005-06-19 22:33:49 +00:00
Ben Gras
9664ba0c4f Started select() implementation.
Added interface to select() for pipes (also named pipes), and select()
stubs for regular files.

Added timer library in FS that select() is the first customer of.


This is unfinished, but committed anyway to get a new release out to
Al and testers.
2005-06-17 13:41:12 +00:00
Jorrit Herder
6d23f072f3 Cleaned up src/lib/utils library. Renamed server_ functions to more logical
names. All system processes can now either use panic() or report() from
libutils, or redefine their own function. Assertions are done via the standard
<assert.h> functionality.
2005-06-01 14:31:00 +00:00
Ben Gras
33bc71c3f5 Don't cache /dev/ram blocks 2005-05-13 13:42:07 +00:00
Ben Gras
9865aeaa79 Initial revision 2005-04-21 14:53:53 +00:00