/*
* Try to free up some pages by shrinking the buffer-cache
*
* Priority tells the routine how hard to try to shrink the
* buffers: 3 means "don't bother too much", while a value
* of 0 means "we'd better get some free pages now".
*/
int shrink_buffers(unsigned int priority)
{
struct buffer_head *bh;
int i;
if (priority < 2)
sync_buffers(0);
bh = free_list;
i = nr_buffers >> priority;
for ( ; i-- > 0 ; bh = bh->b_next_free) {
if (bh->b_count || !bh->b_this_page)
continue;
if (bh->b_lock)
if (priority)
continue;
else
wait_on_buffer(bh);
if (bh->b_dirt) {
ll_rw_block(WRITEA,bh);
continue;
}
if (try_to_free(bh))
return 1;
}
return 0;
}
/*
* Try to free up some pages by shrinking the buffer-cache
*
* Priority tells the routine how hard to try to shrink the
* buffers: 3 means "don't bother too much", while a value
* of 0 means "we'd better get some free pages now".
*/
int shrink_buffers(unsigned int priority)
{
struct buffer_head *bh;
int i;
if (priority < 2)
sync_buffers(0,0);
bh = free_list;
i = nr_buffers >> priority;
for ( ; i-- > 0 ; bh = bh->b_next_free) {
if (bh->b_count ||
(priority >= 5 &&
mem_map[MAP_NR((unsigned long) bh->b_data)] > 1)) {
put_last_free(bh);
continue;
}
if (!bh->b_this_page)
continue;
if (bh->b_lock)
if (priority)
continue;
else
wait_on_buffer(bh);
if (bh->b_dirt) {
bh->b_count++;
ll_rw_block(WRITEA, 1, &bh);
bh->b_count--;
continue;
}
if (try_to_free(bh, &bh))
return 1;
}
return 0;
}
void wtbfree(void *p, unsigned n) {
struct wtbheader *hp, *prevp;
if (headptr == NULL) { /* first use */
if (! (headptr = malloc(sizeof *headptr))) /*can't save fragment, dump it */
return;
headptr->p = p;
headptr->n = n;
headptr->next = NULL;
} else if (p < headptr->p) { /* Special case: less than head */
if ((char *)p + n == headptr->p) { /* merge */
headptr->p = p;
headptr->n = n;
try_to_free(headptr);
if(!headptr->n) { /* delete empty node */
void *tp = headptr;
headptr = headptr->next;
free(tp);
}
} else {
struct wtbheader *tp;
if (! (tp = malloc(sizeof *tp))) /* can't save fragment, dump it */
return;
tp->p = p;
tp->n = n;
tp->next = headptr;
headptr = tp;
}
} else {
for (prevp = hp = headptr; hp->next && p > hp->next->p; prevp = hp, hp = hp->next) {
; /* just advance */
}
if ((char *)hp->p + hp->n == p) { /* merge to current */
hp->n += n;
try_to_free(hp);
if (!hp->n) {
if (hp == headptr)
headptr = NULL;
prevp->next = hp->next;
free(hp);
}
} else if (hp->next && (char *)p + n == hp->next->p) { /* merge to next */
hp->next->p = p;
hp->next->n += n;
try_to_free(hp->next);
if (! hp->next->n) { /* delete empty node */
void *tp = hp->next;
hp->next = hp->next->next;
free(tp);
}
} else { /* insert */
struct wtbheader *tp;
if(! (tp = malloc(sizeof *tp))) /* can't save fragment, dump */
return;
tp->p = p;
tp->n = n;
tp->next = hp->next;
hp->next = tp;
}
}
}
