[lc-checkins] CVS: linux/mm/comp_cache free.c,1.37,1.38 swapout.c,1.61,1.62 vswap.c,1.40,1.41

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Update of /cvsroot/linuxcompressed/linux/mm/comp_cache
In directory usw-pr-cvs1:/tmp/cvs-serv577/mm/comp_cache

Modified Files:
	free.c swapout.c vswap.c 
Log Message:
Bug fixes
o Fixed bug in find_free_swp_buffer() that would leak fragment structs
if the fragment got completely freed while refilling swap buffers.
o Fixed bug in find_free_swp_buffer() that would panic in the case it
couldn't free any swap buffers because of gfp_mask. In this case,
simply return neither decompressing nor writing the dirty fragment.
o Fixed bug in comp_cache_swp_duplicate() (now known as
virtual_swap_duplicate()) that would cause a kernel BUG if duplicating
a freed entry. This scenario may happen in the swapin path code.

Cleanups
o Renamed comp_cache_swp_{duplicate,free,count} -> virtual_swap_*
o Removed useless "nrpages" parameter

Index: free.c
===================================================================
RCS file: /cvsroot/linuxcompressed/linux/mm/comp_cache/free.c,v
retrieving revision 1.37
retrieving revision 1.38
diff -C2 -r1.37 -r1.38
*** free.c	16 Jul 2002 21:58:08 -0000	1.37
--- free.c	17 Jul 2002 13:00:58 -0000	1.38
***************
*** 2,6 ****
   * linux/mm/comp_cache/free.c
   *
!  * Time-stamp: <2002-07-16 18:35:21 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
--- 2,6 ----
   * linux/mm/comp_cache/free.c
   *
!  * Time-stamp: <2002-07-17 08:49:59 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
***************
*** 310,314 ****
  	/* let's proceed to fix swap counter for either entries */
  	for(; num_freed_ptes > 0; --num_freed_ptes) {
! 		comp_cache_swp_free(old_entry);
  		swap_duplicate(entry);
  	}
--- 310,314 ----
  	/* let's proceed to fix swap counter for either entries */
  	for(; num_freed_ptes > 0; --num_freed_ptes) {
! 		virtual_swap_free(vswap->offset);
  		swap_duplicate(entry);
  	}

Index: swapout.c
===================================================================
RCS file: /cvsroot/linuxcompressed/linux/mm/comp_cache/swapout.c,v
retrieving revision 1.61
retrieving revision 1.62
diff -C2 -r1.61 -r1.62
*** swapout.c	16 Jul 2002 21:58:08 -0000	1.61
--- swapout.c	17 Jul 2002 13:00:58 -0000	1.62
***************
*** 2,6 ****
   * /mm/comp_cache/swapout.c
   *
!  * Time-stamp: <2002-07-16 16:35:08 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
--- 2,6 ----
   * /mm/comp_cache/swapout.c
   *
!  * Time-stamp: <2002-07-17 09:42:34 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
***************
*** 24,28 ****

  static int
! refill_swp_buffer(unsigned int gfp_mask, int nrpages, int priority)
  {
  	struct list_head * swp_buffer_lh;
--- 24,28 ----

  static int
! refill_swp_buffer(unsigned int gfp_mask, int priority)
  {
  	struct list_head * swp_buffer_lh;
***************
*** 32,40 ****
  	int wait, maxscan;

! 	maxscan = max(NUM_SWP_BUFFERS/priority, (int) (nrpages * 1.5));
  	wait = 0;

   try_again:
! 	while(--maxscan >= 0 && nrpages && (swp_buffer_lh = swp_used_buffer_head.prev) != &swp_used_buffer_head) {
  		swp_buffer = list_entry(swp_buffer_lh, struct swp_buffer, list);
  		buffer_page = swp_buffer->page;
--- 32,40 ----
  	int wait, maxscan;

! 	maxscan = NUM_SWP_BUFFERS/priority;
  	wait = 0;

   try_again:
! 	while(--maxscan >= 0 && (swp_buffer_lh = swp_used_buffer_head.prev) != &swp_used_buffer_head) {
  		swp_buffer = list_entry(swp_buffer_lh, struct swp_buffer, list);
  		buffer_page = swp_buffer->page;
***************
*** 98,109 ****

  		UnlockPage(buffer_page);
! 		--nrpages;
  	}

  	/* couldn't free any swap buffer? so let's start waiting for
  	 * the lock from the locked pages */
! 	if (!wait && nrpages > 0) {
  		wait = 1;
! 		maxscan = max(NUM_SWP_BUFFERS >> 4, (int) (nrpages * 4));
  		if (unlikely(current->need_resched)) {
                          __set_current_state(TASK_RUNNING);
--- 98,109 ----

  		UnlockPage(buffer_page);
! 		return 1;
  	}

  	/* couldn't free any swap buffer? so let's start waiting for
  	 * the lock from the locked pages */
! 	if (!wait) {
  		wait = 1;
! 		maxscan = NUM_SWP_BUFFERS >> 3;
  		if (unlikely(current->need_resched)) {
                          __set_current_state(TASK_RUNNING);
***************
*** 112,117 ****
  		goto try_again;
  	}
! 
! 	return (nrpages > 0?0:1);
  }

--- 112,116 ----
  		goto try_again;
  	}
! 	return 0;
  }

***************
*** 140,159 ****

  	if (!list_empty(&swp_free_buffer_head))
! 		goto get_a_page;

  	while (list_empty(&swp_free_buffer_head) && priority)
! 		refill_swp_buffer(gfp_mask, 1, priority--);

  	if (list_empty(&swp_free_buffer_head))
! 		panic("couldn't free a swap buffer\n");

! 	/* has the fragment been totally (!IO) or partially
! 	 * freed (Freed)? no need to swap it out any longer */
! 	if (!CompFragmentIO(fragment) || CompFragmentFreed(fragment)) {
! 		CompFragmentClearIO(fragment);
! 		return NULL;
  	}

!  get_a_page:
  	swp_buffer = list_entry(swp_buffer_lh = swp_free_buffer_head.prev, struct swp_buffer, list);

--- 139,163 ----

  	if (!list_empty(&swp_free_buffer_head))
! 		goto get_free_buffer;

  	while (list_empty(&swp_free_buffer_head) && priority)
! 		refill_swp_buffer(gfp_mask, priority--);

+ 	/* Failed to get a free swap buffer. Probably gfp_mask does
+ 	 * not allow buffer sync in refill_swp_buffer() function. */
  	if (list_empty(&swp_free_buffer_head))
! 		goto failed;

! 	/* Fragment totally freed. Free its struct to avoid leakage. */
! 	if (!CompFragmentIO(fragment)) {
! 		kmem_cache_free(fragment_cachep, (fragment));		
! 		goto failed;
  	}

! 	/* Fragment partially freed (to be merged). Nothing to do. */
! 	if (CompFragmentFreed(fragment))
! 		goto failed;
! 	
!  get_free_buffer:
  	swp_buffer = list_entry(swp_buffer_lh = swp_free_buffer_head.prev, struct swp_buffer, list);

***************
*** 174,177 ****
--- 178,185 ----

  	return (swp_buffer);
+ 
+  failed:	
+ 	CompFragmentClearIO(fragment);
+ 	return NULL;
  }

Index: vswap.c
===================================================================
RCS file: /cvsroot/linuxcompressed/linux/mm/comp_cache/vswap.c,v
retrieving revision 1.40
retrieving revision 1.41
diff -C2 -r1.40 -r1.41
*** vswap.c	16 Jul 2002 18:41:55 -0000	1.40
--- vswap.c	17 Jul 2002 13:00:58 -0000	1.41
***************
*** 2,6 ****
   * linux/mm/comp_cache/vswap.c
   *
!  * Time-stamp: <2002-07-16 14:57:52 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
--- 2,6 ----
   * linux/mm/comp_cache/vswap.c
   *
!  * Time-stamp: <2002-07-17 08:52:56 rcastro>
   *  
   * Linux Virtual Memory Compressed Cache
***************
*** 238,245 ****
   */
  int
! comp_cache_swp_duplicate(swp_entry_t entry)
  {
  	unsigned long offset = SWP_OFFSET(entry);
- 	int ret = 0;

  	if (!vswap_address(entry))
--- 238,244 ----
   */
  int
! virtual_swap_duplicate(swp_entry_t entry)
  {
  	unsigned long offset = SWP_OFFSET(entry);

  	if (!vswap_address(entry))
***************
*** 248,265 ****
  		BUG();
  	if (!vswap_address[offset]->swap_count)
! 		BUG();
  	if (offset >= vswap_current_num_entries)
! 		goto out;
! 	
  	vswap_address[offset]->swap_count++;
! 	ret = 1;
!  out:
! 	return ret;
  }

  /**
!  * comp_cache_swp_free - swap_free for virtual swap addresses.
!  * @entry: the virtual swap entry which will have its count
!  * decremented and possibly the vswap entry freed.
   *
   * This function will decrement the vswap entry counter. If we have
--- 247,261 ----
  		BUG();
  	if (!vswap_address[offset]->swap_count)
! 		return 0;
  	if (offset >= vswap_current_num_entries)
! 		return 0;	
  	vswap_address[offset]->swap_count++;
! 	return 1;
  }

  /**
!  * virtual_swap_free - swap_free for virtual swap addresses.  @entry:
!  * the virtual swap entry which will have its count decremented and
!  * possibly the vswap entry freed.
   *
   * This function will decrement the vswap entry counter. If we have
***************
*** 272,285 ****
   */
  int
! comp_cache_swp_free(swp_entry_t entry)
  {
- 	unsigned long offset = SWP_OFFSET(entry);
  	unsigned int swap_count;
  	struct comp_cache_fragment * fragment;
  	struct vswap_address * vswap;

- 	if (!vswap_address(entry))
- 		BUG();
- 
  	if (offset >= vswap_current_num_entries)
  		BUG();
--- 268,277 ----
   */
  int
! virtual_swap_free(unsigned long offset)
  {
  	unsigned int swap_count;
  	struct comp_cache_fragment * fragment;
  	struct vswap_address * vswap;

  	if (offset >= vswap_current_num_entries)
  		BUG();
***************
*** 345,349 ****

  /**
!  * comp_cache_swp_count - swap_count for virtual swap addresses.
   * @entry: virtual swap entry that will be returned its counter.
   *
--- 337,341 ----

  /**
!  * virtual_swap_count - swap_count for virtual swap addresses.
   * @entry: virtual swap entry that will be returned its counter.
   *
***************
*** 351,364 ****
   */
  int
! comp_cache_swp_count(swp_entry_t entry)
  {
  	unsigned long offset = SWP_OFFSET(entry);
- 	
- 	if (!vswap_address(entry))
- 		BUG();
- 	
  	if (!vswap_address[offset]->swap_count)
  		BUG();
- 	
  	return (vswap_address[offset]->swap_count);
  }
--- 343,351 ----
   */
  int
! virtual_swap_count(swp_entry_t entry)
  {
  	unsigned long offset = SWP_OFFSET(entry);
  	if (!vswap_address[offset]->swap_count)
  		BUG();
  	return (vswap_address[offset]->swap_count);
  }