[lc-checkins] CVS: linux/include/linux comp_cache.h,1.97,1.98

[Rodrigo S. de C. <rc...@us...>]

Update of /cvsroot/linuxcompressed/linux/include/linux
In directory usw-pr-cvs1:/tmp/cvs-serv23025/include/linux

Modified Files:
	comp_cache.h 
Log Message:
Bug fixes
o Fixed "kernel BUG at inode.c:518". That bug happened when, after
truncating all the pages from an inode, there are still pending pages
in that mapping. That scenario could occur if a certain fragment
happens to waiting to lock its comp_page in order to be effectively
freed. In this case, the fragment got removed from comp cache data
structures, but not from the mapping data structures while waiting for
its fragment->comp_page lock, so it was taken as being in the mapping
(well, as a clean mapped page actually) in spite of having a zero
counter. That was fixed by removing the fragment from the mapping
structures too.

o Fixed "oops in ext2_check_page()" bug. That bug could happen because
a page, after being compressed in compress_clean_page(), could be
removed from page cache (in shrink_cache()) even if it is not freeable
(!is_page_cache_freeable()). So, ext2_check_page(), which assumes that
the page wouldn't be removed since it has a reference on the page,
accesses directly the page->mapping pointer and oopses, because that
pointer is set to NULL after removing from page cache. The fix was
very simple. We check, with the pagecache lock held, if the page is
freeable after compressing it. In this case, it is not removed from
page cache and is kept on the inactive list.

Cleanup
o Cleanup in lookup_comp_pages()
o find_and_dirty_page() renamed to find_or_add_page()
o __find_lock_page() does not read pages from comp cache if the page
is not found in page cache.



Index: comp_cache.h
===================================================================
RCS file: /cvsroot/linuxcompressed/linux/include/linux/comp_cache.h,v
retrieving revision 1.97
retrieving revision 1.98
diff -C2 -r1.97 -r1.98
*** comp_cache.h	28 Jul 2002 15:47:04 -0000	1.97
--- comp_cache.h	31 Jul 2002 12:31:05 -0000	1.98
***************
*** 2,6 ****
   * linux/mm/comp_cache.h
   *
!  * Time-stamp: <2002-07-28 10:08:41 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
--- 2,6 ----
   * linux/mm/comp_cache.h
   *
!  * Time-stamp: <2002-07-29 09:43:00 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
***************
*** 63,68 ****
  	unsigned short offset;
  	
- 	/* index != 0 && compressed_size == 0 => page stored uncompressed     */
- 	/* index == 0 && compressed_size != 0 => compressed_size = free_space */
  	unsigned short compressed_size;
  	unsigned long flags;
--- 63,66 ----